Raspberry Pi Case

John McCoy <[email protected]> wrote:
> Leon <lcb11211@swbelldotnet> wrote in news:RZadnZ9w85XqcWbLnZ2dnUU7-
> [email protected]:
>
>
>> Nope, in a sealed speaker the same amount of air is in the enclosure
>> regardless if the speaker cone is moving in or out.
>
> Not to beat a dead horse, but you are the one confused.
> Go look up Boyle's Law on Wikipedia.
>
> John
>

Regardless, boules law has nothing to do with a speaker working correctly
whether it is ported or whether it is an air suspension/acoustical style
speaker.
Your earlier comments indicated that speakers had to be ported to equalize
air pressure on both sides of the speaker unless the enclosure was large
and the speakers were small. That simply is not true.

On 3/28/2016 5:46 PM, tdacon wrote:
>
>
> "Puckdropper" wrote in message
> news:[email protected]...
>
>> It makes sense to make some form of grill or hole in the wood to make
>> sure
>> the sound can pass unobstructed. I could possibly cut 1/8" wide slots
>> with
>> an endmill or drill a series of holes. Which would be better, or does it
>> matter?
>
>> Also, I'd like to keep little bits of debris from sticking to the speaker
>> cone. Would a piece of cotton cloth or something similar work as
>> "speaker
>> fabric" without affecting the sound too much?
>
>> Puckdropper
>
> Simplest might be to just bore a hole a little smaller than the diameter
> of the speaker cone, and glue a very light piece of cloth across the
> opening between the wood and the speaker. Shouldn't have much of an
> effect on the sound, if any. Maybe your wife or girlfriend has a pair of
> black nylons she's about ready to throw away ;-)

For that application (all things considered) he could probably glue a
piece of cheese cloth over the opening and never know the difference
other than a VERY slight degradation in volume. In short, most anything
would work. Nylons would work but I'd have some concerns about longevity.

On 3/29/2016 2:03 AM, OFWW wrote:
> On Mon, 28 Mar 2016 18:32:45 -0500, Unquestionably Confused
> <[email protected]> wrote:
>
>> On 3/28/2016 5:46 PM, tdacon wrote:
>>>
>>>
>>> "Puckdropper" wrote in message
>>> news:[email protected]...
>>>
>>>> It makes sense to make some form of grill or hole in the wood to make
>>>> sure
>>>> the sound can pass unobstructed. I could possibly cut 1/8" wide slots
>>>> with
>>>> an endmill or drill a series of holes. Which would be better, or does it
>>>> matter?
>>>
>>>> Also, I'd like to keep little bits of debris from sticking to the speaker
>>>> cone. Would a piece of cotton cloth or something similar work as
>>>> "speaker
>>>> fabric" without affecting the sound too much?
>>>
>>>> Puckdropper
>>>
>>> Simplest might be to just bore a hole a little smaller than the diameter
>>> of the speaker cone, and glue a very light piece of cloth across the
>>> opening between the wood and the speaker. Shouldn't have much of an
>>> effect on the sound, if any. Maybe your wife or girlfriend has a pair of
>>> black nylons she's about ready to throw away ;-)
>>
>> For that application (all things considered) he could probably glue a
>> piece of cheese cloth over the opening and never know the difference
>> other than a VERY slight degradation in volume. In short, most anything
>> would work. Nylons would work but I'd have some concerns about longevity.
>>
>>
> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
> better and have a sexy sound. (g) but the best would be a stiffer
> cloth.
>
> If the speaker is going in a box the harder the wood the more it
> reflects sound. Also drill a small hole for the back side of the
> speaker to allow the diaphragm to fluctuate freely, you can tune the
> speaker by the size of the hole.

All valid points but in this instance he refers to 1/8" slots covering
the speaker opening. I wouldn't be worried too much about the
"stretchiness" of the cloth nor, for that matter, the porosity (read:
Acoustic Transparency) of that material. Likewise, if we go away from
1/8" slots, we may find that SWMBO's used panty hose will not be
sufficiently strong to withstand repeated finger pokes after x number of
months of exposure to UV light, etc.

Unquestionably Confused <[email protected]> wrote in
news:[email protected]:

>
> All valid points but in this instance he refers to 1/8" slots covering
> the speaker opening. I wouldn't be worried too much about the
> "stretchiness" of the cloth nor, for that matter, the porosity (read:
> Acoustic Transparency) of that material. Likewise, if we go away from
> 1/8" slots, we may find that SWMBO's used panty hose will not be
> sufficiently strong to withstand repeated finger pokes after x number
> of months of exposure to UV light, etc.
>

I'm thinking about just gluing the fabric to the backside of the speaker
grill, which should take care of things nicely. I'm not worried about
fingers or stuff like that getting in, just the annoying little bits of
debris that these things tend to collect and can sometimes be a pain to
remove.

The speaker has its own enclosure, and the enclosure will be mounted to the
case.

Puckdropper

Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
[email protected]:

*snip & trim*

>
> That is not true either. Long ago many speakers were built to be air
> tight. Case in point many subwolfers use a driver speaker and a slave
> speaker inside the same enclosure. The whole speaker assembly is
> dependent on being air tight for the slave speaker to function and
> produce sound.
>
> And the speakers do not move enough to be hampered by air that easily
> compressed or expands from the movement of the speaker. I have a
> totally enclosed 12" subwolfer with no issues.

What would the slave speaker tend to look like? Basically like a speaker
without a magnet? I picked up a speaker from Walmart that had one real
speaker and one that kinda looked like a decoy or fake speaker.

*snip & trim*

Puckdropper

OFWW <[email protected]> wrote in
news:[email protected]:

>
> I'm curious, is your Pi for a special purpose or experimentation? How
> did you get one so fast?
>

It's mainly for playing with right now. I've got a Pi 2 that I'm hooking
up my Digitrax PR3 programmer to, and may do so with the Pi 3.

I got lucky, I guess. I ordered the official touch screen from MCM and
preordered a Pi 3 about 3 weeks before it was available. They delayed
shipping the touch screen until the Pi 3 was available.

The touch screen is a nice bit of hardware, I've played with it for several
hours already and the only problems I have are basically Fitt's Law
related... Kinda hard to hit a 5-pixel by 10-pixel target with your huge
50x50 pixel fingers.

Puckdropper

Mike Marlow <[email protected]> wrote in
news:[email protected]:

> Mike Marlow wrote:
>>
>> Agreed Leon - I did come into it late and maybe I misunderstood some
>> points from the time I came in. I picked up on it where I thought I
>> read that a sealed cabinet had a constant volume and that's where my
>> initial comment entered. Sealed backs are one thing but there is no
>> such thing as a speaker cabinet with a sealed compartment. At the
>> very least, atmospheric pressure enters the chamber through the
>> speaker cone.
>>
>
> On second thought - maybe I really do not understand enough about
> speaker design to make the statement that I made above...
>

I do know that Soundtraxx Mini-oval speakers have an enclosure that the
speaker fits tightly into, magnet side out. There is no hole for a vent
in that enclosure, nor is one needed. At the same time, though, realize
the dimensions of the speaker & enclosure are only about 8mm by 20mm.
Sometimes rules change as things get smaller.

Puckdropper

Swingman <[email protected]> wrote in
news:[email protected]:


> Been intrigued with the concept behind Raspberry Pi since it first
> came out. They sure have hit on something I would have died for when I
> built my first Heathkit in '68. Can you imagine, we'd probably rule
> the world by now. LOL
>
> Been thinking about getting one just for the hell of it, possibly to
> cobble up a streaming audio/video cord cutting device, maybe using
> KOBI?
>
> You got any interest/info in that direction?
>
> Thanks ...
>

A tiny bit... Unfortunately, Amazon Prime doesn't work with Linux. It
boils down to DRM and lack of interest in making something that works.

MythTV OTOH, runs great on Linux. I wouldn't be surprised to find
there's a "Myth Pi" project.

The Pi doesn't get high marks for audio out of the box. There's a $25
sound board add-on that will give you better audio, but if good sound is
your aim you may want to look at other options.

Puckdropper

Swingman <[email protected]> wrote in news:LOydnSPV2YozXmPLnZ2dnUU7-
[email protected]:

> On 4/1/2016 1:05 PM, OFWW wrote:
>
>> Put an LED bar in the rear window and send text messages to the
>> drivers behind you.;)
>
> Not something I'd try in Texas... lol
>

Why's that? Afraid an Aggie will pull up beside, roll down the window and
ask you to read the message?

Puckdropper

OFWW <[email protected]> wrote in
news:[email protected]:

>
> Like you, I have been considering getting one for a while, and the ver
> 3 is the hot ticket for wireless robots or whatever.
> Put an LED bar in the rear window and send text messages to the
> drivers behind you. ;)

Time to quit thinking about it and separate yourself from about $50.
You'll need a MicroSD card too.

The Pi 3 does come with integrated wireless, so there's $10 saved there.

Puckdropper

Swingman <[email protected]> wrote in
news:[email protected]:

> On 4/1/2016 2:23 PM, Puckdropper wrote:
>> Swingman <[email protected]> wrote in news:LOydnSPV2YozXmPLnZ2dnUU7-
>> [email protected]:
>>
>>> On 4/1/2016 1:05 PM, OFWW wrote:
>>>
>>>> Put an LED bar in the rear window and send text messages to the
>>>> drivers behind you.;)
>>>
>>> Not something I'd try in Texas... lol
>>>
>>
>> Why's that? Afraid an Aggie will pull up beside, roll down the
>> window and ask you to read the message?
>
> More likely some yankee transplant wanting to know if had the latest
> hockey scores.
>

What good is it if it doesn't?

Puckdropper

OFWW <[email protected]> wrote in news:p5p0gbpukr4u52sb26qt390r0ah9cekg8k@
4ax.com:


> Which class of card, I've got a bunch. I might just have a look
> tomorrow it there is no crowd, hate crowds.
>

As fast as you can get, Class 10 I think is the current max.

>>The Pi 3 does come with integrated wireless, so there's $10 saved there.
>>
> And blue tooth, so my input devices should work.
>
> shoot, so little time and so much to do. :(
>>Puckdropper
>

AFAIK, Bluetooth isn't ready yet.

Puckdropper

krw <[email protected]> wrote in
news:[email protected]:

> On 03 Apr 2016 03:46:29 GMT, Puckdropper
> <puckdropper(at)yahoo(dot)com> wrote:
>>
>>AFAIK, Bluetooth isn't ready yet.
>>
> I haven't had any trouble with Bluetooth in a few years (and I use it
> extensively, now). Before that, I would have agreed with you.
>

Oh, I meant the Bluetooth on the Pi 3. Ok, I did a little more looking
and the current knowledge in one forum thread* suggests that Bluetooth
support is there in Raspbian Jessie, but you may need to install a few
things for a GUI interface.

You can safely ignore that statement above ("AFAIK, Bluetooth isn't ready
yet.") and just do some reading if things don't work. (Linux--The OS
that brought reading back to America's youth! lol)

Puckdropper
*https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=138145
Just citing my source.

On 03 Apr 2016 03:46:29 GMT, Puckdropper
<puckdropper(at)yahoo(dot)com> wrote:

>OFWW <[email protected]> wrote in news:p5p0gbpukr4u52sb26qt390r0ah9cekg8k@
>4ax.com:
>
>
>> Which class of card, I've got a bunch. I might just have a look
>> tomorrow it there is no crowd, hate crowds.
>>
>
>As fast as you can get, Class 10 I think is the current max.
>
>>>The Pi 3 does come with integrated wireless, so there's $10 saved there.
>>>
>> And blue tooth, so my input devices should work.
>>
>> shoot, so little time and so much to do. :(
>>>Puckdropper
>>
>
>AFAIK, Bluetooth isn't ready yet.
>
I haven't had any trouble with Bluetooth in a few years (and I use it
extensively, now). Before that, I would have agreed with you.

On 28 Mar 2016 22:10:44 GMT, Puckdropper
<puckdropper(at)yahoo(dot)com> wrote:

>I've got a Raspberry Pi 3 and the official Raspberry Pi Touchscreen that
>I'm working on building a case for. I've come across a design decision I'd
>like a little input on.
>
>I have an amplifier and speaker arrangement to give me basic sound. I'm
>using 2 small speakers, about 1" by 2". The speakers are in their own
>plastic enclosure with a provision to mount the speaker using a
>sufficiently small screw, probably 2-56 maybe 1-72. FWIW, the case will
>probably be pine.
>
>It makes sense to make some form of grill or hole in the wood to make sure
>the sound can pass unobstructed. I could possibly cut 1/8" wide slots with
>an endmill or drill a series of holes. Which would be better, or does it
>matter?
>
>Also, I'd like to keep little bits of debris from sticking to the speaker
>cone. Would a piece of cotton cloth or something similar work as "speaker
>fabric" without affecting the sound too much?
>
>Thanks,
>
>Puckdropper

I'm curious, is your Pi for a special purpose or experimentation? How
did you get one so fast?

On 3/29/2016 1:20 PM, John McCoy wrote:
> Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
> news:[email protected]:
>
>> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
>> [email protected]:
>
>>> That is not true either. Long ago many speakers were built to be air
>>> tight. Case in point many subwolfers use a driver speaker and a
>>> slave speaker inside the same enclosure. The whole speaker assembly
>>> is dependent on being air tight for the slave speaker to function and
>>> produce sound.
>
>> What would the slave speaker tend to look like? Basically like a
>> speaker without a magnet? I picked up a speaker from Walmart that had
>> one real speaker and one that kinda looked like a decoy or fake
>> speaker.
>
> Slave speaker is a special case - in that case the slave is
> moving outward when the driven speaker is moving inward, and
> vice-versa, so the volume of air inside the enclosure doesn't
> change.


The air volume does not change in a sealed speaker either. The pressure
does change but not the volume.




>
> With two driven speakers, if the enclosure is airtight you're
> compressing (or decompressing) the air in the enclosure, which
> is generating a force opposing the way the speaker is being
> driven.

Not so if the speakers are air tight in their own compartments inside
the speaker housing, which apparently is how my center speaker with 2,
5" speakers is set up.


How much force depends on how big the speaker is, and
> how much volume is in the enclosure. If your enclosure is
> small, it can have an appreciable effect.
>
> John
>

On 3/30/2016 1:27 PM, Mike Marlow wrote:
> Leon wrote:
>
>>
>> Yes, speaker cone movement in a sealed enclosure neither creates or
>> eliminates air. It simply compresses and decompress the air.
>>
>
> Not really Leon. The front of the speaker enclosure is open - or else
> you wouldn't hear the sound. Volume does change instantaneously as the
> cone moves. When you are pushing air out, you can't be sucking air in
> at the same time if the enclosure is sealed and the only opening is
> where the air is being pushed out. Compressing air if it can't escape
> to the outside world would not create sound in the outside world.
>
\>

Naturally the front of the speaker cone is open, but the back is/was
often ins an air tight environment.


I hate looking the info up but this kinda supports my comments.

http://www.audioholics.com/loudspeaker-design/sealed-vs-ported

On 3/30/2016 4:51 PM, Mike Marlow wrote:
> Leon wrote:
>
>>
>> Naturally the front of the speaker cone is open, but the back is/was
>> often ins an air tight environment.
>>
>>
>> I hate looking the info up but this kinda supports my comments.
>>
>
> Well... not so much. If I understand your earlier comments correctly,
> you are interpreting a sealed chamber to mean an completely sealed
> chamber. That's the point I commented on. It's not completely sealed
> as long as the front of the speaker is open. The balance of the speaker
> cabinet is neutralized to atmospheric pressure by that opening. It's
> only that sound is directed by that sealed back. Not that volume and/or
> pressure remain constant.
>
>

No the front of the speaker is open, obviously but the box in many cases
is air tight. You probably came into the conversation late and are
missing the key points.

Previous posts indicated the need for a vented port so that the speaker
would operate. I said that this was not true. There seemed to be some
thoughts that a speaker would not operate if it had a sealed compartment
behind it, which is not true.

On 3/31/2016 3:34 PM, Scott Lurndal wrote:

> I tend to favor one of these over both rPi and Arduino:
>
> http://www.hardkernel.com/main/main.php

Wow, New one on me.
The plot, and options, thicken.
Glad I asked.

Thanks!

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
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http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

On 4/1/2016 1:05 PM, OFWW wrote:

> Put an LED bar in the rear window and send text messages to the
> drivers behind you.;)

Not something I'd try in Texas... lol

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

On 3/31/2016 1:38 PM, Larry Blanchard wrote:
> On Thu, 31 Mar 2016 13:25:39 -0500, Swingman wrote:
>
>> Been intrigued with the concept behind Raspberry Pi since it first came
>> out.
>
> Agreed. But I find the Arduinos much more fun. Not a "computer", a
> "controller" Bunches of digital and analog I/O, with accessory boards do
> do almost anything. Great fun on a model RR, and the robotics people buy
> them by the dozen - a clone of the Uno model can be had for less than $10.

Seen the technology and it is also intriguing. Just wonder how TV
streaming from a digital signal to multiple units.

What I've heard about tasking with both, "If you can describe it with
less than two ‘and’s, get an Arduino. If you need more than two ‘and’s,
get a Raspberry Pi".

What do you think? Thanks.

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

Swingman <[email protected]> writes:
>On 3/31/2016 3:34 PM, Scott Lurndal wrote:
>
>> I tend to favor one of these over both rPi and Arduino:
>>
>> http://www.hardkernel.com/main/main.php
>
>Wow, New one on me.
>The plot, and options, thicken.
>Glad I asked.

One of the nice things about attending ARMTechCon every
year, is you get to drool over the cool stuff.

http://www.armtechcon.com/

On 3/30/2016 1:48 AM, OFWW wrote:
> On Tue, 29 Mar 2016 21:48:19 -0400, krw <[email protected]> wrote:
>
>> On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
>> wrote:
>>
>>> On 3/29/2016 1:20 PM, John McCoy wrote:
>>>> Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
>>>> news:[email protected]:
>>>>
>>>>> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
>>>>> [email protected]:
>>>>
>>>>>> That is not true either. Long ago many speakers were built to be air
>>>>>> tight. Case in point many subwolfers use a driver speaker and a
>>>>>> slave speaker inside the same enclosure. The whole speaker assembly
>>>>>> is dependent on being air tight for the slave speaker to function and
>>>>>> produce sound.
>>>>
>>>>> What would the slave speaker tend to look like? Basically like a
>>>>> speaker without a magnet? I picked up a speaker from Walmart that had
>>>>> one real speaker and one that kinda looked like a decoy or fake
>>>>> speaker.
>>>>
>>>> Slave speaker is a special case - in that case the slave is
>>>> moving outward when the driven speaker is moving inward, and
>>>> vice-versa, so the volume of air inside the enclosure doesn't
>>>> change.
>>>
>>>
>>> The air volume does not change in a sealed speaker either. The pressure
>>> does change but not the volume.
>>>
>> The volume of air obviously changes as the volume increases. ;-) The
>> quantity of air is constant, the pressure is changing, so the volume
>> must change (inversely). Remember, the speaker cone is moving.
>
> Yet if there is no vent the volume of air does not change, only the
> pressure changes. So the sound is dampened in that the speaker is not
> free to fully travel, unless it is a metal coned speaker. I believe
> that is what Leon was referring to.

Yes, speaker cone movement in a sealed enclosure neither creates or
eliminates air. It simply compresses and decompress the air.

On 3/30/2016 9:47 AM, John McCoy wrote:
> OFWW <[email protected]> wrote in
> news:[email protected]:
>
>> On Tue, 29 Mar 2016 21:48:19 -0400, krw <[email protected]> wrote:
>>
>>> On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
>>> wrote:
>
>>>> The air volume does not change in a sealed speaker either. The
>>>> pressure does change but not the volume.
>>>>
>>> The volume of air obviously changes as the volume increases. ;-) The
>>> quantity of air is constant, the pressure is changing, so the volume
>>> must change (inversely). Remember, the speaker cone is moving.
>>
>> Yet if there is no vent the volume of air does not change, only the
>> pressure changes. So the sound is dampened in that the speaker is not
>> free to fully travel, unless it is a metal coned speaker. I believe
>> that is what Leon was referring to.
>
> Eh? You guys are trying to re-write the laws of physics here.
> Boyle's gas law applies, p1v1 = p2v2, just as krw said.
>
> This is not complicated - assume there is a speaker in a
> sealed box. The speaker cone moves as it's being driven with
> the audio signal. As the cone moves outward, the volume
> inside the box increases, and the pressure decreases. As
> it moves inwards, the volume in the box decreases and the
> pressure increases.

Nope, in a sealed speaker the same amount of air is in the enclosure
regardless if the speaker cone is moving in or out. What you are
confusing is displacement. The measurable area, not air volume, inside
the speaker changes but not the volume of air. Air easily compressed
and decompresses, that does not decrease the volume of air.



>
> As noted (several times) whether these changes are significant
> depends on the size of the box relative to the speaker.
>
> John
>

On 3/29/2016 8:43 PM, krw wrote:
> On Tue, 29 Mar 2016 15:43:40 -0000 (UTC), John McCoy
> <[email protected]> wrote:
>
>> OFWW <[email protected]> wrote in
>> news:[email protected]:
>>
>>> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
>>> better and have a sexy sound. (g) but the best would be a stiffer
>>> cloth.
>>
>> This sort of depends on how concerned you are with the sound
>> quality. A soft, porous cloth will attenuate the sound, and
>> affect the tone. If you want good acoustics, use a stiff cloth.
>> If you just want to keep debris out, use whatever's handy.
>>
>>> If the speaker is going in a box the harder the wood the more it
>>> reflects sound. Also drill a small hole for the back side of the
>>> speaker to allow the diaphragm to fluctuate freely, you can tune the
>>> speaker by the size of the hole.
>>
>> This is important - not the tuning, but having some sort of
>> vent on the backside of the speaker. A speaker makes sound
>> by pushing air forwards and back, and if there's no way for
>> air to move behind the speaker, it's not going to move much
>> air in front either. Result - not much sound. (this is
>> assuming the box is smallish - a big box with small speakers
>> has enough volume inside it won't need a vent).
>
> That depends on the speaker. "Acoustic suspension" speakers aren't
> ported. They rely on the back pressure to return the speaker to its
> midpoint.


AKA Air Suspension speakers.

On 3/29/2016 8:48 PM, krw wrote:
> On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
> wrote:
>
>> On 3/29/2016 1:20 PM, John McCoy wrote:
>>> Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
>>> news:[email protected]:
>>>
>>>> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
>>>> [email protected]:
>>>
>>>>> That is not true either. Long ago many speakers were built to be air
>>>>> tight. Case in point many subwolfers use a driver speaker and a
>>>>> slave speaker inside the same enclosure. The whole speaker assembly
>>>>> is dependent on being air tight for the slave speaker to function and
>>>>> produce sound.
>>>
>>>> What would the slave speaker tend to look like? Basically like a
>>>> speaker without a magnet? I picked up a speaker from Walmart that had
>>>> one real speaker and one that kinda looked like a decoy or fake
>>>> speaker.
>>>
>>> Slave speaker is a special case - in that case the slave is
>>> moving outward when the driven speaker is moving inward, and
>>> vice-versa, so the volume of air inside the enclosure doesn't
>>> change.
>>
>>
>> The air volume does not change in a sealed speaker either. The pressure
>> does change but not the volume.
>>
> The volume of air obviously changes as the volume increases. ;-) The
> quantity of air is constant, the pressure is changing, so the volume
> must change (inversely). Remember, the speaker cone is moving.

The volume remains the same, where does it go when it is in a sealed
container? Would volume and quantity be the same measurement?
Now if the speaker has an opening the volume does change. Speaker
movement in a sealed cabinet would simply increase and decrease
pressure. We are measuring air, not displacement. Displacement would
certainly change.




>>
>>
>>>
>>> With two driven speakers, if the enclosure is airtight you're
>>> compressing (or decompressing) the air in the enclosure, which
>>> is generating a force opposing the way the speaker is being
>>> driven.
>>
>> Not so if the speakers are air tight in their own compartments inside
>> the speaker housing, which apparently is how my center speaker with 2,
>> 5" speakers is set up.
>>
>>
>> How much force depends on how big the speaker is, and
>>> how much volume is in the enclosure. If your enclosure is
>>> small, it can have an appreciable effect.
>>>
>>> John
>>>

OFWW <[email protected]> wrote in
news:[email protected]:

> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
> better and have a sexy sound. (g) but the best would be a stiffer
> cloth.

This sort of depends on how concerned you are with the sound
quality. A soft, porous cloth will attenuate the sound, and
affect the tone. If you want good acoustics, use a stiff cloth.
If you just want to keep debris out, use whatever's handy.

> If the speaker is going in a box the harder the wood the more it
> reflects sound. Also drill a small hole for the back side of the
> speaker to allow the diaphragm to fluctuate freely, you can tune the
> speaker by the size of the hole.

This is important - not the tuning, but having some sort of
vent on the backside of the speaker. A speaker makes sound
by pushing air forwards and back, and if there's no way for
air to move behind the speaker, it's not going to move much
air in front either. Result - not much sound. (this is
assuming the box is smallish - a big box with small speakers
has enough volume inside it won't need a vent).

Also, since you have two speakers, make sure they are phased
correctly. If you connect them out of phase, they will cancel
each other, and again you get not much sound. This is more
of a problem with big bass speakers, but even with small ones
it's worth checking the plug is right way round.

John

Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
news:[email protected]:

> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
> [email protected]:

>> That is not true either. Long ago many speakers were built to be air
>> tight. Case in point many subwolfers use a driver speaker and a
>> slave speaker inside the same enclosure. The whole speaker assembly
>> is dependent on being air tight for the slave speaker to function and
>> produce sound.

> What would the slave speaker tend to look like? Basically like a
> speaker without a magnet? I picked up a speaker from Walmart that had
> one real speaker and one that kinda looked like a decoy or fake
> speaker.

Slave speaker is a special case - in that case the slave is
moving outward when the driven speaker is moving inward, and
vice-versa, so the volume of air inside the enclosure doesn't
change.

With two driven speakers, if the enclosure is airtight you're
compressing (or decompressing) the air in the enclosure, which
is generating a force opposing the way the speaker is being
driven. How much force depends on how big the speaker is, and
how much volume is in the enclosure. If your enclosure is
small, it can have an appreciable effect.

John

OFWW <[email protected]> wrote in
news:[email protected]:

> On Tue, 29 Mar 2016 21:48:19 -0400, krw <[email protected]> wrote:
>
>>On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
>>wrote:

>>>The air volume does not change in a sealed speaker either. The
>>>pressure does change but not the volume.
>>>
>>The volume of air obviously changes as the volume increases. ;-) The
>>quantity of air is constant, the pressure is changing, so the volume
>>must change (inversely). Remember, the speaker cone is moving.
>
> Yet if there is no vent the volume of air does not change, only the
> pressure changes. So the sound is dampened in that the speaker is not
> free to fully travel, unless it is a metal coned speaker. I believe
> that is what Leon was referring to.

Eh? You guys are trying to re-write the laws of physics here.
Boyle's gas law applies, p1v1 = p2v2, just as krw said.

This is not complicated - assume there is a speaker in a
sealed box. The speaker cone moves as it's being driven with
the audio signal. As the cone moves outward, the volume
inside the box increases, and the pressure decreases. As
it moves inwards, the volume in the box decreases and the
pressure increases.

As noted (several times) whether these changes are significant
depends on the size of the box relative to the speaker.

John

Leon <lcb11211@swbelldotnet> wrote in news:RZadnZ9w85XqcWbLnZ2dnUU7-
[email protected]:


> Nope, in a sealed speaker the same amount of air is in the enclosure
> regardless if the speaker cone is moving in or out.

Not to beat a dead horse, but you are the one confused.
Go look up Boyle's Law on Wikipedia.

John

Leon <[email protected]> wrote in
news:1432699139.481121657.728927.lcb11211-swbell.net@news.giganews.com:

> Your earlier comments indicated that speakers had to be ported to
> equalize air pressure on both sides of the speaker unless the
> enclosure was large and the speakers were small. That simply is not
> true.

What I actually said (regardless of what you think I
"indicated") was that you won't get as much sound if the
case isn't vented. Which is simply true and always will
be (except, as krw pointed out, in the special case of
air suspension speakers).

Actually, there is another special case - if the enclosure
is thin enough to flex. In that case the enclosure itself
will act like a slave speaker. This tends to sound really
awful.

John

Larry Blanchard <[email protected]> wrote in
news:[email protected]:

> On Thu, 31 Mar 2016 13:25:39 -0500, Swingman wrote:
>
>> Been intrigued with the concept behind Raspberry Pi since it first
>> came out.
>
> Agreed. But I find the Arduinos much more fun. Not a "computer", a
> "controller" Bunches of digital and analog I/O, with accessory boards
> do do almost anything. Great fun on a model RR, and the robotics
> people buy them by the dozen - a clone of the Uno model can be had for
> less than $10.

Yeah, that's a bit of an apples and oranges comparison; the
Raspberry Pi has more of the architecture of a smart phone,
while the Arduino is the classic embedded controller.

I'm not a great fan of the "true" Arduino, because I'm not a
huge fan of the Atmel AVR processor (altho it's a lot better
than the PIC processor). There are Arduino compatible boards
using various flavors of ARM processors (like the STM32) which
I think are better.

John

notbob <[email protected]> wrote in
news:[email protected]:

> That might be a problem. My older RPi B+ (?) uses a USB wiki dongle,
> which can be changed fer a better dongle if yer current dongle is not
> very good. With the new RPi, yer stuck with the wifi it comes with.
> Hopefully, it comes with a good one.

You should be able to disable the onboard wifi and use a
USB dongle if you want to (which might be something you'd
do if you put it in a metal case, since the onboard wifi
antenna is soldered to the board and can't be moved).

However, one of the weaknesses of the Pi is that a lot of
the low-level hardware stuff is not all that well documented,
so it might take some work to figure out just how to do it.

John

Swingman <[email protected]> writes:
>On 3/31/2016 1:38 PM, Larry Blanchard wrote:
>> On Thu, 31 Mar 2016 13:25:39 -0500, Swingman wrote:
>>
>>> Been intrigued with the concept behind Raspberry Pi since it first came
>>> out.
>>
>> Agreed. But I find the Arduinos much more fun. Not a "computer", a
>> "controller" Bunches of digital and analog I/O, with accessory boards do
>> do almost anything. Great fun on a model RR, and the robotics people buy
>> them by the dozen - a clone of the Uno model can be had for less than $10.
>
>Seen the technology and it is also intriguing. Just wonder how TV
>streaming from a digital signal to multiple units.
>
>What I've heard about tasking with both, "If you can describe it with
>less than two ‘and’s, get an Arduino. If you need more than two ‘and’s,
>get a Raspberry Pi".
>
>What do you think? Thanks.

I tend to favor one of these over both rPi and Arduino:

http://www.hardkernel.com/main/main.php

On 3/31/2016 11:06 AM, John McCoy wrote:
> Leon <[email protected]> wrote in
> news:1432699139.481121657.728927.lcb11211-swbell.net@news.giganews.com:
>
>> Your earlier comments indicated that speakers had to be ported to
>> equalize air pressure on both sides of the speaker unless the
>> enclosure was large and the speakers were small. That simply is not
>> true.
>
> What I actually said (regardless of what you think I
> "indicated") was that you won't get as much sound if the
> case isn't vented. Which is simply true and always will
> be (except, as krw pointed out, in the special case of
> air suspension speakers).
>
> Actually, there is another special case - if the enclosure
> is thin enough to flex. In that case the enclosure itself
> will act like a slave speaker. This tends to sound really
> awful.
>
> John
>


Air tight speakers, non vented, have been being manufactured since the
50's There simply is no issue with the amount of sound that comes from
them.

On 3/31/2016 10:07 AM, Swingman wrote:
> On 3/30/2016 5:24 PM, Leon wrote:
>
>> No the front of the speaker is open, obviously but the box in many cases
>> is air tight. You probably came into the conversation late and are
>> missing the key points.
>
> Yep ... the idea of sealed enclosure speakers, a very specific type of
> speaker design, is to allow the air behind the speaker to act pretty
> much like a spring, which helps control the movement of the speaker
> within its design limits.
>
> It would have to be (relatively) "sealed" in order to do so.
>


It's about time!

LOL. Thanks for stepping in and commenting.

On Mon, 28 Mar 2016 18:32:45 -0500, Unquestionably Confused
<[email protected]> wrote:

>On 3/28/2016 5:46 PM, tdacon wrote:
>>
>>
>> "Puckdropper" wrote in message
>> news:[email protected]...
>>
>>> It makes sense to make some form of grill or hole in the wood to make
>>> sure
>>> the sound can pass unobstructed. I could possibly cut 1/8" wide slots
>>> with
>>> an endmill or drill a series of holes. Which would be better, or does it
>>> matter?
>>
>>> Also, I'd like to keep little bits of debris from sticking to the speaker
>>> cone. Would a piece of cotton cloth or something similar work as
>>> "speaker
>>> fabric" without affecting the sound too much?
>>
>>> Puckdropper
>>
>> Simplest might be to just bore a hole a little smaller than the diameter
>> of the speaker cone, and glue a very light piece of cloth across the
>> opening between the wood and the speaker. Shouldn't have much of an
>> effect on the sound, if any. Maybe your wife or girlfriend has a pair of
>> black nylons she's about ready to throw away ;-)
>
>For that application (all things considered) he could probably glue a
>piece of cheese cloth over the opening and never know the difference
>other than a VERY slight degradation in volume. In short, most anything
>would work. Nylons would work but I'd have some concerns about longevity.
>
>
Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
better and have a sexy sound. (g) but the best would be a stiffer
cloth.

If the speaker is going in a box the harder the wood the more it
reflects sound. Also drill a small hole for the back side of the
speaker to allow the diaphragm to fluctuate freely, you can tune the
speaker by the size of the hole.

On 3/29/2016 10:43 AM, John McCoy wrote:
> OFWW <[email protected]> wrote in
> news:[email protected]:
>
>> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
>> better and have a sexy sound. (g) but the best would be a stiffer
>> cloth.
>
> This sort of depends on how concerned you are with the sound
> quality. A soft, porous cloth will attenuate the sound, and
> affect the tone. If you want good acoustics, use a stiff cloth.
> If you just want to keep debris out, use whatever's handy.

FWIW I have not ever witnessed this. Maybe a little if the cloth is
denser/thicker than the length of the sound waves and that is more if a
concern for higher notes where the sound is more directional. But I
used drapery material in from of my L?R and center speakers and you can
not tell if the material/door is open or closed.






>
>> If the speaker is going in a box the harder the wood the more it
>> reflects sound. Also drill a small hole for the back side of the
>> speaker to allow the diaphragm to fluctuate freely, you can tune the
>> speaker by the size of the hole.
>
> This is important - not the tuning, but having some sort of
> vent on the backside of the speaker. A speaker makes sound
> by pushing air forwards and back, and if there's no way for
> air to move behind the speaker, it's not going to move much
> air in front either. Result - not much sound. (this is
> assuming the box is smallish - a big box with small speakers
> has enough volume inside it won't need a vent).

That is not true either. Long ago many speakers were built to be air
tight. Case in point many subwolfers use a driver speaker and a slave
speaker inside the same enclosure. The whole speaker assembly is
dependent on being air tight for the slave speaker to function and
produce sound.

And the speakers do not move enough to be hampered by air that easily
compressed or expands from the movement of the speaker. I have a
totally enclosed 12" subwolfer with no issues.


>
> Also, since you have two speakers, make sure they are phased
> correctly. If you connect them out of phase, they will cancel
> each other, and again you get not much sound. This is more
> of a problem with big bass speakers, but even with small ones
> it's worth checking the plug is right way round.
>
> John
>


Swingman would be the one to consult here, he has built, owned and
operated recording studios. He told me that the material would not
matter when covering my entertainment center doors with drapery
material, and you cannot tell the difference. My only concern was that
the weave was not so dense that IR light would not pass through. I
simply held the material up to a light to see if the light penetrated.

On 2016-03-30, Mike Marlow <[email protected]> wrote:

> On second thought - maybe I really do not understand enough about
> speaker design to make the statement that I made above...

BUT!!! ....we cannot possibly extend such an equally forgiving POV to
ol' notbob. He's obviously wrong and not deserving of our
forgiveness. Die, notbob! Die!

(c'mon, Mike, ya' know you wanna say it)

We having fun, yet? ;)

nb

On 2016-03-30, Mike Marlow <[email protected]> wrote:

> Dude - you are one sick puppy.

Mike - I'm too old to be a "Dude" and I've never been a "puppy". I
will admit my being "sick" is still in question, though. OTOH, if you
wanna dog me in this newsgroup, I'm up for it.

Despite having givin up this nonsense, years ago, the diminishing size
of usenet has made me long for more interaction. Wanna be my dance
partner? ;)

nb

On 2016-04-01, Puckdropper <puckdropper> wrote:

> The Pi 3 does come with integrated wireless, so there's $10 saved there.

That might be a problem. My older RPi B+ (?) uses a USB wiki dongle, which
can be changed fer a better dongle if yer current dongle is not very
good. With the new RPi, yer stuck with the wifi it comes with.
Hopefully, it comes with a good one.

For example, I passed on the official RPi mini dongle and got the
better b/g/n thumb drive-sized dongle. OTOH, the RPi 3 has a better
CPU. ;)

nb

On 3/30/2016 5:40 PM, Mike Marlow wrote:

> On second thought - maybe I really do not understand enough about
> speaker design to make the statement that I made above...

Yep, and I built my own bass cabinets, as well as a few for others back
when I was young, and sexy, enough to lug an Ampex SVT head around. ;)

Most of the speaker cabinets I built contained 15" woofers, moved a lot
of air, and were baffled/ported" very precisely according to speaker
cabinet gurus I knew when doing studio work, as well as some being
direct copies of well known speaker cabinets ... much like I would
reproduce a chair for someone these days.

There is ton of physics that goes into designing a pleasing sounding
speaker ... with a bit of magic thrown. My studio was a (paid) test bed
for many of the more well known studio speakers down through the years.

I can say yeah or nay for the sound, but certainly wouldn't presume to
expound definitely on the physics, particularly when it comes to the
highly dynamic volume/pressures of air, inside and out, therefore the
precise "porting" requirements, in order to tune certain types of
speakers to a very specific frequency for desired bass reproduction.

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

On 3/30/2016 5:24 PM, Leon wrote:

> No the front of the speaker is open, obviously but the box in many cases
> is air tight. You probably came into the conversation late and are
> missing the key points.

Yep ... the idea of sealed enclosure speakers, a very specific type of
speaker design, is to allow the air behind the speaker to act pretty
much like a spring, which helps control the movement of the speaker
within its design limits.

It would have to be (relatively) "sealed" in order to do so.

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

On Thu, 31 Mar 2016 15:27:53 -0500, Swingman <[email protected]> wrote:

>On 3/31/2016 1:38 PM, Larry Blanchard wrote:
>> On Thu, 31 Mar 2016 13:25:39 -0500, Swingman wrote:
>>
>>> Been intrigued with the concept behind Raspberry Pi since it first came
>>> out.
>>
>> Agreed. But I find the Arduinos much more fun. Not a "computer", a
>> "controller" Bunches of digital and analog I/O, with accessory boards do
>> do almost anything. Great fun on a model RR, and the robotics people buy
>> them by the dozen - a clone of the Uno model can be had for less than $10.
>
>Seen the technology and it is also intriguing. Just wonder how TV
>streaming from a digital signal to multiple units.
>

Direct TV does that now, in home. Both audio and TV. It has been
do-able over the Net with multi-casting and for the life of me I don't
know why it was kept so limited. One signal that anyone had hook up to
if they know where it's from. saves a lot of bandwidth instead of one
stream to each individual user.

>What I've heard about tasking with both, "If you can describe it with
>less than two ‘and’s, get an Arduino. If you need more than two ‘and’s,
>get a Raspberry Pi".
>
>What do you think? Thanks.

Like you, I have been considering getting one for a while, and the ver
3 is the hot ticket for wireless robots or whatever.
Put an LED bar in the rear window and send text messages to the
drivers behind you. ;)

On 3/28/2016 5:10 PM, Puckdropper wrote:
> I've got a Raspberry Pi 3 and the official Raspberry Pi Touchscreen that
> I'm working on building a case for. I've come across a design decision I'd
> like a little input on.
>
> I have an amplifier and speaker arrangement to give me basic sound. I'm
> using 2 small speakers, about 1" by 2". The speakers are in their own
> plastic enclosure with a provision to mount the speaker using a
> sufficiently small screw, probably 2-56 maybe 1-72. FWIW, the case will
> probably be pine.

Been intrigued with the concept behind Raspberry Pi since it first came
out. They sure have hit on something I would have died for when I built
my first Heathkit in '68. Can you imagine, we'd probably rule the world
by now. LOL

Been thinking about getting one just for the hell of it, possibly to
cobble up a streaming audio/video cord cutting device, maybe using KOBI?

You got any interest/info in that direction?

Thanks ...

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
https://www.facebook.com/eWoodShop-206166666122228
KarlCaillouet@ (the obvious)

On 04 Apr 2016 00:37:21 GMT, Puckdropper
<puckdropper(at)yahoo(dot)com> wrote:

>krw <[email protected]> wrote in
>news:[email protected]:
>
>> On 03 Apr 2016 03:46:29 GMT, Puckdropper
>> <puckdropper(at)yahoo(dot)com> wrote:
>>>
>>>AFAIK, Bluetooth isn't ready yet.
>>>
>> I haven't had any trouble with Bluetooth in a few years (and I use it
>> extensively, now). Before that, I would have agreed with you.
>>
>
>Oh, I meant the Bluetooth on the Pi 3. Ok, I did a little more looking
>and the current knowledge in one forum thread* suggests that Bluetooth
>support is there in Raspbian Jessie, but you may need to install a few
>things for a GUI interface.

Ah, I misunderstood you incorrectly. Nevermind! ;-)
>
>You can safely ignore that statement above ("AFAIK, Bluetooth isn't ready
>yet.") and just do some reading if things don't work. (Linux--The OS
>that brought reading back to America's youth! lol)

;-)

On Tue, 29 Mar 2016 07:32:52 -0500, Unquestionably Confused
<[email protected]> wrote:

>On 3/29/2016 2:03 AM, OFWW wrote:
>> On Mon, 28 Mar 2016 18:32:45 -0500, Unquestionably Confused
>> <[email protected]> wrote:
>>
>>> On 3/28/2016 5:46 PM, tdacon wrote:
>>>>
>>>>
>>>> "Puckdropper" wrote in message
>>>> news:[email protected]...
>>>>
>>>>> It makes sense to make some form of grill or hole in the wood to make
>>>>> sure
>>>>> the sound can pass unobstructed. I could possibly cut 1/8" wide slots
>>>>> with
>>>>> an endmill or drill a series of holes. Which would be better, or does it
>>>>> matter?
>>>>
>>>>> Also, I'd like to keep little bits of debris from sticking to the speaker
>>>>> cone. Would a piece of cotton cloth or something similar work as
>>>>> "speaker
>>>>> fabric" without affecting the sound too much?
>>>>
>>>>> Puckdropper
>>>>
>>>> Simplest might be to just bore a hole a little smaller than the diameter
>>>> of the speaker cone, and glue a very light piece of cloth across the
>>>> opening between the wood and the speaker. Shouldn't have much of an
>>>> effect on the sound, if any. Maybe your wife or girlfriend has a pair of
>>>> black nylons she's about ready to throw away ;-)
>>>
>>> For that application (all things considered) he could probably glue a
>>> piece of cheese cloth over the opening and never know the difference
>>> other than a VERY slight degradation in volume. In short, most anything
>>> would work. Nylons would work but I'd have some concerns about longevity.
>>>
>>>
>> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
>> better and have a sexy sound. (g) but the best would be a stiffer
>> cloth.
>>
>> If the speaker is going in a box the harder the wood the more it
>> reflects sound. Also drill a small hole for the back side of the
>> speaker to allow the diaphragm to fluctuate freely, you can tune the
>> speaker by the size of the hole.
>
>All valid points but in this instance he refers to 1/8" slots covering
>the speaker opening. I wouldn't be worried too much about the
>"stretchiness" of the cloth nor, for that matter, the porosity (read:
>Acoustic Transparency) of that material. Likewise, if we go away from
>1/8" slots, we may find that SWMBO's used panty hose will not be
>sufficiently strong to withstand repeated finger pokes after x number of
>months of exposure to UV light, etc.

Yeah, you are right about that, I was not even thinking of the fact
that it is a plastic material.

On 3/29/2016 1:05 PM, Puckdropper wrote:
> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
> [email protected]:
>
> *snip & trim*
>
>>
>> That is not true either. Long ago many speakers were built to be air
>> tight. Case in point many subwolfers use a driver speaker and a slave
>> speaker inside the same enclosure. The whole speaker assembly is
>> dependent on being air tight for the slave speaker to function and
>> produce sound.
>>
>> And the speakers do not move enough to be hampered by air that easily
>> compressed or expands from the movement of the speaker. I have a
>> totally enclosed 12" subwolfer with no issues.
>
> What would the slave speaker tend to look like? Basically like a speaker
> without a magnet? I picked up a speaker from Walmart that had one real
> speaker and one that kinda looked like a decoy or fake speaker.

That would be it! If you dare thump the driven speaker the slave should
move a bit.





>
> *snip & trim*
>
> Puckdropper
>

"Puckdropper" wrote in message
news:[email protected]...

>It makes sense to make some form of grill or hole in the wood to make sure
>the sound can pass unobstructed. I could possibly cut 1/8" wide slots with
>an endmill or drill a series of holes. Which would be better, or does it
>matter?

>Also, I'd like to keep little bits of debris from sticking to the speaker
>cone. Would a piece of cotton cloth or something similar work as "speaker
>fabric" without affecting the sound too much?

>Puckdropper

Simplest might be to just bore a hole a little smaller than the diameter of
the speaker cone, and glue a very light piece of cloth across the opening
between the wood and the speaker. Shouldn't have much of an effect on the
sound, if any. Maybe your wife or girlfriend has a pair of black nylons
she's about ready to throw away ;-)

Tom

Leon wrote:

>
> Yes, speaker cone movement in a sealed enclosure neither creates or
> eliminates air. It simply compresses and decompress the air.
>

Not really Leon. The front of the speaker enclosure is open - or else
you wouldn't hear the sound. Volume does change instantaneously as the
cone moves. When you are pushing air out, you can't be sucking air in
at the same time if the enclosure is sealed and the only opening is
where the air is being pushed out. Compressing air if it can't escape
to the outside world would not create sound in the outside world.


--
-Mike-
[email protected]

Leon wrote:

>
> Naturally the front of the speaker cone is open, but the back is/was
> often ins an air tight environment.
>
>
> I hate looking the info up but this kinda supports my comments.
>

Well... not so much. If I understand your earlier comments correctly,
you are interpreting a sealed chamber to mean an completely sealed
chamber. That's the point I commented on. It's not completely sealed
as long as the front of the speaker is open. The balance of the speaker
cabinet is neutralized to atmospheric pressure by that opening. It's
only that sound is directed by that sealed back. Not that volume and/or
pressure remain constant.


--
-Mike-
[email protected]

Leon wrote:
> On 3/30/2016 4:51 PM, Mike Marlow wrote:
>> Leon wrote:
>>
>>>
>>> Naturally the front of the speaker cone is open, but the back is/was
>>> often ins an air tight environment.
>>>
>>>
>>> I hate looking the info up but this kinda supports my comments.
>>>
>>
>> Well... not so much. If I understand your earlier comments correctly,
>> you are interpreting a sealed chamber to mean an completely sealed
>> chamber. That's the point I commented on. It's not completely sealed
>> as long as the front of the speaker is open. The balance of the speaker
>> cabinet is neutralized to atmospheric pressure by that opening. It's
>> only that sound is directed by that sealed back. Not that volume and/or
>> pressure remain constant.
>>
>>
>
> No the front of the speaker is open, obviously but the box in many cases
> is air tight. You probably came into the conversation late and are
> missing the key points.
>
> Previous posts indicated the need for a vented port so that the speaker
> would operate. I said that this was not true. There seemed to be some
> thoughts that a speaker would not operate if it had a sealed compartment
> behind it, which is not true.

Agreed Leon - I did come into it late and maybe I misunderstood some
points from the time I came in. I picked up on it where I thought I
read that a sealed cabinet had a constant volume and that's where my
initial comment entered. Sealed backs are one thing but there is no
such thing as a speaker cabinet with a sealed compartment. At the very
least, atmospheric pressure enters the chamber through the speaker cone.

--
-Mike-
[email protected]

Mike Marlow wrote:
> Leon wrote:
>> On 3/30/2016 4:51 PM, Mike Marlow wrote:
>>> Leon wrote:
>>>
>>>>
>>>> Naturally the front of the speaker cone is open, but the back is/was
>>>> often ins an air tight environment.
>>>>
>>>>
>>>> I hate looking the info up but this kinda supports my comments.
>>>>
>>>
>>> Well... not so much. If I understand your earlier comments correctly,
>>> you are interpreting a sealed chamber to mean an completely sealed
>>> chamber. That's the point I commented on. It's not completely sealed
>>> as long as the front of the speaker is open. The balance of the speaker
>>> cabinet is neutralized to atmospheric pressure by that opening. It's
>>> only that sound is directed by that sealed back. Not that volume and/or
>>> pressure remain constant.
>>>
>>>
>>
>> No the front of the speaker is open, obviously but the box in many cases
>> is air tight. You probably came into the conversation late and are
>> missing the key points.
>>
>> Previous posts indicated the need for a vented port so that the speaker
>> would operate. I said that this was not true. There seemed to be some
>> thoughts that a speaker would not operate if it had a sealed compartment
>> behind it, which is not true.
>
> Agreed Leon - I did come into it late and maybe I misunderstood some
> points from the time I came in. I picked up on it where I thought I
> read that a sealed cabinet had a constant volume and that's where my
> initial comment entered. Sealed backs are one thing but there is no
> such thing as a speaker cabinet with a sealed compartment. At the very
> least, atmospheric pressure enters the chamber through the speaker cone.
>

On second thought - maybe I really do not understand enough about
speaker design to make the statement that I made above...

--
-Mike-
[email protected]

notbob wrote:
> On 2016-03-30, Mike Marlow <[email protected]> wrote:
>
>> On second thought - maybe I really do not understand enough about
>> speaker design to make the statement that I made above...
>
> BUT!!! ....we cannot possibly extend such an equally forgiving POV to
> ol' notbob. He's obviously wrong and not deserving of our
> forgiveness. Die, notbob! Die!
>
> (c'mon, Mike, ya' know you wanna say it)
>
> We having fun, yet? ;)
>

Dude - you are one sick puppy.


--
-Mike-
[email protected]

On Thu, 31 Mar 2016 13:25:39 -0500, Swingman wrote:

> Been intrigued with the concept behind Raspberry Pi since it first came
> out.

Agreed. But I find the Arduinos much more fun. Not a "computer", a
"controller" Bunches of digital and analog I/O, with accessory boards do
do almost anything. Great fun on a model RR, and the robotics people buy
them by the dozen - a clone of the Uno model can be had for less than $10.


--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.

On Thu, 31 Mar 2016 15:27:53 -0500, Swingman wrote:

> What I've heard about tasking with both, "If you can describe it with
> less than two ‘and’s, get an Arduino. If you need more than two ‘and’s,
> get a Raspberry Pi".

The Pi is designed to be a low cost PC for children, students, and 3rd
world. Hook up a monitor, a keyboard, and even a hard drive if you
like. You've got a somewhat slow computer running most Linux
applications.

The Arduino and other microcontrollers are designed to ,well, control
things. There are digital and analog inputs and outputs varying from 20
or so on the Uno to 70 or so on the Mega2560. You use a PC (or a Pi) to
write the programs and download them over a USB cable.

There's a Google group using Arduinos for all sorts of model RR
applications. I'm using them to control servos and move turnout points
slowly and realistically at a lot lower cost than the commercial
product. And infinitely more cusomizeable.

Woodworking? A moisture meter would be pretty simple. A liquor cabinet
that weighed each bottle and played "How Dry I Am" when appropriate?
Twinkling LED lights behind the cloth in a speaker enclosure?

One experimenter built a hearing aid using an Arduino. A little large to
fit in the ear, but is sure shows there's not a lot of expensive
components involved.





--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.

Haven't you seen signs in the country and back woods - nation wide!

If it isn't the hunters shooting holes in signs to sight in,
it is the drive by fun loving redneck that throws a bottle into
it or shoots it next time.

Just don't ask for bullets or bottles.

Martin


On 4/1/2016 1:53 PM, Swingman wrote:
> On 4/1/2016 1:05 PM, OFWW wrote:
>
>> Put an LED bar in the rear window and send text messages to the
>> drivers behind you.;)
>
> Not something I'd try in Texas... lol
>

On 01 Apr 2016 19:25:45 GMT, Puckdropper
<puckdropper(at)yahoo(dot)com> wrote:

>OFWW <[email protected]> wrote in
>news:[email protected]:
>
>>
>> Like you, I have been considering getting one for a while, and the ver
>> 3 is the hot ticket for wireless robots or whatever.
>> Put an LED bar in the rear window and send text messages to the
>> drivers behind you. ;)
>
>Time to quit thinking about it and separate yourself from about $50.
>You'll need a MicroSD card too.
>

Which class of card, I've got a bunch. I might just have a look
tomorrow it there is no crowd, hate crowds.

>The Pi 3 does come with integrated wireless, so there's $10 saved there.
>
And blue tooth, so my input devices should work.

shoot, so little time and so much to do. :(
>Puckdropper

On Tue, 29 Mar 2016 21:48:19 -0400, krw <[email protected]> wrote:

>On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
>wrote:
>
>>On 3/29/2016 1:20 PM, John McCoy wrote:
>>> Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
>>> news:[email protected]:
>>>
>>>> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
>>>> [email protected]:
>>>
>>>>> That is not true either. Long ago many speakers were built to be air
>>>>> tight. Case in point many subwolfers use a driver speaker and a
>>>>> slave speaker inside the same enclosure. The whole speaker assembly
>>>>> is dependent on being air tight for the slave speaker to function and
>>>>> produce sound.
>>>
>>>> What would the slave speaker tend to look like? Basically like a
>>>> speaker without a magnet? I picked up a speaker from Walmart that had
>>>> one real speaker and one that kinda looked like a decoy or fake
>>>> speaker.
>>>
>>> Slave speaker is a special case - in that case the slave is
>>> moving outward when the driven speaker is moving inward, and
>>> vice-versa, so the volume of air inside the enclosure doesn't
>>> change.
>>
>>
>>The air volume does not change in a sealed speaker either. The pressure
>>does change but not the volume.
>>
>The volume of air obviously changes as the volume increases. ;-) The
>quantity of air is constant, the pressure is changing, so the volume
>must change (inversely). Remember, the speaker cone is moving.

Yet if there is no vent the volume of air does not change, only the
pressure changes. So the sound is dampened in that the speaker is not
free to fully travel, unless it is a metal coned speaker. I believe
that is what Leon was referring to.

>>
>>
>>>
>>> With two driven speakers, if the enclosure is airtight you're
>>> compressing (or decompressing) the air in the enclosure, which
>>> is generating a force opposing the way the speaker is being
>>> driven.
>>
>>Not so if the speakers are air tight in their own compartments inside
>>the speaker housing, which apparently is how my center speaker with 2,
>>5" speakers is set up.
>>
>>
>> How much force depends on how big the speaker is, and
>>> how much volume is in the enclosure. If your enclosure is
>>> small, it can have an appreciable effect.
>>>
>>> John
>>>

On Tue, 29 Mar 2016 14:12:26 -0500, Leon <lcb11211@swbelldotnet>
wrote:

>On 3/29/2016 1:20 PM, John McCoy wrote:
>> Puckdropper <puckdropper(at)yahoo(dot)com> wrote in
>> news:[email protected]:
>>
>>> Leon <lcb11211@swbelldotnet> wrote in news:d-ednSYZkf_9JmfLnZ2dnUU7-
>>> [email protected]:
>>
>>>> That is not true either. Long ago many speakers were built to be air
>>>> tight. Case in point many subwolfers use a driver speaker and a
>>>> slave speaker inside the same enclosure. The whole speaker assembly
>>>> is dependent on being air tight for the slave speaker to function and
>>>> produce sound.
>>
>>> What would the slave speaker tend to look like? Basically like a
>>> speaker without a magnet? I picked up a speaker from Walmart that had
>>> one real speaker and one that kinda looked like a decoy or fake
>>> speaker.
>>
>> Slave speaker is a special case - in that case the slave is
>> moving outward when the driven speaker is moving inward, and
>> vice-versa, so the volume of air inside the enclosure doesn't
>> change.
>
>
>The air volume does not change in a sealed speaker either. The pressure
>does change but not the volume.
>
The volume of air obviously changes as the volume increases. ;-) The
quantity of air is constant, the pressure is changing, so the volume
must change (inversely). Remember, the speaker cone is moving.
>
>
>>
>> With two driven speakers, if the enclosure is airtight you're
>> compressing (or decompressing) the air in the enclosure, which
>> is generating a force opposing the way the speaker is being
>> driven.
>
>Not so if the speakers are air tight in their own compartments inside
>the speaker housing, which apparently is how my center speaker with 2,
>5" speakers is set up.
>
>
> How much force depends on how big the speaker is, and
>> how much volume is in the enclosure. If your enclosure is
>> small, it can have an appreciable effect.
>>
>> John
>>

On Tue, 29 Mar 2016 15:43:40 -0000 (UTC), John McCoy
<[email protected]> wrote:

>OFWW <[email protected]> wrote in
>news:[email protected]:
>
>> Cheesecloth is too pores (SP) too soft/stretchy. Nylon's would be
>> better and have a sexy sound. (g) but the best would be a stiffer
>> cloth.
>
>This sort of depends on how concerned you are with the sound
>quality. A soft, porous cloth will attenuate the sound, and
>affect the tone. If you want good acoustics, use a stiff cloth.
>If you just want to keep debris out, use whatever's handy.
>
>> If the speaker is going in a box the harder the wood the more it
>> reflects sound. Also drill a small hole for the back side of the
>> speaker to allow the diaphragm to fluctuate freely, you can tune the
>> speaker by the size of the hole.
>
>This is important - not the tuning, but having some sort of
>vent on the backside of the speaker. A speaker makes sound
>by pushing air forwards and back, and if there's no way for
>air to move behind the speaker, it's not going to move much
>air in front either. Result - not much sound. (this is
>assuming the box is smallish - a big box with small speakers
>has enough volume inside it won't need a vent).

That depends on the speaker. "Acoustic suspension" speakers aren't
ported. They rely on the back pressure to return the speaker to its
midpoint.
>
>Also, since you have two speakers, make sure they are phased
>correctly. If you connect them out of phase, they will cancel
>each other, and again you get not much sound. This is more
>of a problem with big bass speakers, but even with small ones
>it's worth checking the plug is right way round.

On 4/1/2016 2:23 PM, Puckdropper wrote:
> Swingman <[email protected]> wrote in news:LOydnSPV2YozXmPLnZ2dnUU7-
> [email protected]:
>
>> On 4/1/2016 1:05 PM, OFWW wrote:
>>
>>> Put an LED bar in the rear window and send text messages to the
>>> drivers behind you.;)
>>
>> Not something I'd try in Texas... lol
>>
>
> Why's that? Afraid an Aggie will pull up beside, roll down the window and
> ask you to read the message?

More likely some yankee transplant wanting to know if had the latest
hockey scores.

--
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KarlCaillouet@ (the obvious)