Replacement Cabin Speaker for Cessna?

[John Clonts]

Anybody know where to get a replacement cabin speaker other than
Cessna? They want $110 for it!

This is for a Cessna 210M. The speaker has 4 terminals. Two of them
are wired to ground. One of the others is from the audio output, and
the other is from the stall and landing gear horn unit.

--
Thanks!
John Clonts
Temple, Texas
N7NZ

[[email protected]]

John Clonts > wrote:
: Anybody know where to get a replacement cabin speaker other than
: Cessna? They want $110 for it!

: This is for a Cessna 210M. The speaker has 4 terminals. Two of them
: are wired to ground. One of the others is from the audio output, and
: the other is from the stall and landing gear horn unit.

Hahahaha! $110... now that's over the top. The aircraft speakers I've seen
have been 4ohm *or* 8ohm. They can be set up either way... depends on how the other
things (like audio panel) are configured. If you can figure out which way it's set
up, buying a compatible on from Radio Sh*t would seem to be in order. Make sure to
check your compass after the install!

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[RST Engineering]

Use your head, sir. THe speaker is an oddball double voice coil unit that
can be driven with either radio or warning horns. Rat Shack wouldn't even
know a double voice coil speaker if it bit them in the hiney.

I'd suggest that John contact Neal's Speaker Repair in Sacramento. He's
done some work for me and does a damned fine job of it ... and if he says he
can't get double coil repair parts, you've got Cessna to deal with.

Jim



> wrote in message
...
>
> Hahahaha! $110... now that's over the top. The aircraft speakers I've
> seen
> have been 4ohm *or* 8ohm. They can be set up either way... depends on how
> the other
> things (like audio panel) are configured. If you can figure out which way
> it's set
> up, buying a compatible on from Radio Sh*t would seem to be in order.
> Make sure to
> check your compass after the install!
>
> -Cory
>
> --
>
> ************************************************** ***********************
> * Cory Papenfuss *
> * Electrical Engineering candidate Ph.D. graduate student *
> * Virginia Polytechnic Institute and State University *
> ************************************************** ***********************
>

[John Clonts]

"RST Engineering" > wrote in message ...

> I'd suggest that John contact Neal's Speaker Repair in Sacramento. He's done some work for me and does a
> damned fine job of it ... and if he says he can't get double coil repair parts, you've got Cessna to deal
> with.
>

Hello Jim, I have done just that, thanks!

I don't know much about audio, but isn't there some kind of "2-to-1 transformer" which could be put in there
to "combine" the two audio signals and drive a conventional ($15?) speaker?

Cheers,
John

[RST Engineering]

I play fast and loose with the design of aircraft systems UNTIL it comes to
some sort of safety-of-flight consideration.

Yes, of COURSE I could tell you how to drive one speaker from two audio
sources using a transformer. Would it provide the same reliability that a
dual-cone speaker gave you? I don't know because I can't run the tests that
the Cessna engineer ran to certify the sucker. I'm not about to tell you
how to do something that would compromise that design.

Having SAID that, I'm more than willing to discuss how to drive a single 8
ohm speaker from two audio sources PROVIDED that I'm not told that one of
them is the horns for the stall and landing gear. That would violate my
personal comfort limits.

Jim





"John Clonts" > wrote in message
...
>
> "RST Engineering" > wrote in message
> ...
>
>> I'd suggest that John contact Neal's Speaker Repair in Sacramento. He's
>> done some work for me and does a damned fine job of it ... and if he says
>> he can't get double coil repair parts, you've got Cessna to deal with.
>>
>
> Hello Jim, I have done just that, thanks!
>
> I don't know much about audio, but isn't there some kind of "2-to-1
> transformer" which could be put in there to "combine" the two audio
> signals and drive a conventional ($15?) speaker?
>
> Cheers,
> John
>

[John Clonts]

>Yes, of COURSE I could tell you how to drive one speaker from two audio
>sources using a transformer. Would it provide the same reliability that a
>dual-cone speaker gave you? I don't know because I can't run the tests that
>the Cessna engineer ran to certify the sucker. I'm not about to tell you
>how to do something that would compromise that design.

Sorry, no, I was speaking from the standpoint of "Couldn't the Cessna
engineers have designed it to use a conventional speaker, using some
sort of transformer...etc". I take your answer to mean basically "yes,
but perhaps they felt this was more reliable, etc". I doubt the Cessna
engineers considered the effect that many a pilot (not me, of course)
would continue to fly their plane without warning horns while he was
trying to find and order an oddball speaker whereas he would have just
picked one up from Radio Shack and put it in, had it been a standard
off the shelf unit. :) :)

BTW, Mr. Neal replied right away, that he did not have the parts for it
:(

Thanks,
John

[[email protected]]

RST Engineering > wrote:
: Use your head, sir. THe speaker is an oddball double voice coil unit that
: can be driven with either radio or warning horns. Rat Shack wouldn't even
: know a double voice coil speaker if it bit them in the hiney.

: I'd suggest that John contact Neal's Speaker Repair in Sacramento. He's
: done some work for me and does a damned fine job of it ... and if he says he
: can't get double coil repair parts, you've got Cessna to deal with.

: Jim

My ignorance of the Cessna dual voice coil aside, I do know that dual voice
coil speakers are used in audio system. Generally, it's for subwoofers, though, so
something small enough for an aircraft audio system would likely be a specialty item.

My experience was with my own PA-28 with dual taps on the voice coils... one
for 8ohm, one for 4ohm. All my (relevant) avionics I installed had selections for 4/8
ohm speaker settings. I assumed this was a typical choice, but I'm apparently
incorrect.

Interesting to consider that "emergency systems" such as alarms and horns use
a speaker for annunciation.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[RST Engineering]

I'd place it in the STOOPID category.





Now, not that I'd recommend it for a certificated aircraft, but if I needed
such a device on my tractor, I'd go down to Rat Shack and get an 8 ohm
speaker that would fit the hole departed by the old speaker. I'd also buy a
273-1366 110vac - 25vacct transformer. One side of the speaker is grounded.
Take the transformer and cut off the PRIMARY (110 vac sice) leads very close
to the transformer; they will not be used. Run the AUDIO to one side of the
secondary, run the HORN to the other side of the secondary, and run the
center tap of the secondary to the remaining speaker terminal.

All you can do is try it. I openly admit that I've never tried this scheme
for adding audio signals, but it SHOULD work. If it doesn't, then an OEM
speaker may be the only answer.

Report results here that we may all learn.

Jim


>
> Interesting to consider that "emergency systems" such as alarms and horns
> use
> a speaker for annunciation.

[RST Engineering]

And a second thought that didn't present itself until I thought a little
more. Can you fit two smaller speakers in the same space as the original
speaker? With the speaker technology we have today, we can get excellent
sound out of small speakers.

You may have to fabricate a mounting plate to make it happen, but this seems
to be a fairly decent solution.

Jim


>
> Report results here that we may all learn.
>

[Roy Smith]

RST Engineering > wrote:
>Now, not that I'd recommend it for a certificated aircraft, but if I needed
>such a device on my tractor, I'd go down to Rat Shack and get an 8 ohm
>speaker that would fit the hole departed by the old speaker. I'd also buy a
>273-1366 110vac - 25vacct transformer. One side of the speaker is grounded.
>Take the transformer and cut off the PRIMARY (110 vac sice) leads very close
>to the transformer; they will not be used. Run the AUDIO to one side of the
>secondary, run the HORN to the other side of the secondary, and run the
>center tap of the secondary to the remaining speaker terminal.

Jim,

You must be the only guy I know who owns a tractor with a stall
warning horn :-)

[Mike W.]

You ever see a Farmall spin accident? It ain't pretty.

"Roy Smith" > wrote in message
...

> Jim,
>
> You must be the only guy I know who owns a tractor with a stall
> warning horn :-)

[John Clonts]

Yes, good idea!

Cessna is backordered for that part til late January, so I'm gonna have
to do something. For a stopgap I may just put in a standard speaker
and hook only the gear/stall horn to it. I use headphones for my comm
audio anyway...

Thanks,
John

[Mike W.]

What size is the original speaker? 4"x6" ? Find out if it is a common
automotive speaker size. Go to your local electronics closeout store or
online catalog place and find a 2-way or 3-way speaker that will fit in the
original opening. What I propose is similar in thought to Jim's idea.

With a little electronics know-how, you can electrically seperate the main
cone (woofer) from the tweeter. Use the main cone for the voice from the
comm, and the smaller for the stall horn. Since most car audio stuff is 4
ohm, you might want to put a resistor in series with the speaker so you
don't cook the audio amp in your radio.

--
Hello, my name is Mike, and I am an airplane addict....

[John Clonts]

"Mike W." > wrote in message ...
> What size is the original speaker? 4"x6" ? Find out if it is a common
> automotive speaker size. Go to your local electronics closeout store or
> online catalog place and find a 2-way or 3-way speaker that will fit in the
> original opening. What I propose is similar in thought to Jim's idea.
>
> With a little electronics know-how, you can electrically seperate the main
> cone (woofer) from the tweeter. Use the main cone for the voice from the
> comm, and the smaller for the stall horn. Since most car audio stuff is 4
> ohm, you might want to put a resistor in series with the speaker so you
> don't cook the audio amp in your radio.
>

Hello Mike,

Mine is round, 5.25 inch. My Radio Shack is a mall outlet, no components, but I found a speaker at-- get
this-- Walmart!

Thats a good idea about the 2 way speaker. By "electrically separate the main cone from the tweeter", do you
mean they will have the 4 teensy wires coming from the coils to 2 terminals on terminal strip, and I will just
need to snip the proper ones and provide separate terminal connection to it? I do think I could handle that!

I believe my existing speaker is 4 ohms also. At least it measures about 4 ohms with my cheap DVM-- but I know
that's just measuring its DC resistance, how can I tell what its impedance is? (My electronics experience is
mostly in digital!)


Thanks!
John

[David Lesher]

"John Clonts" > writes:


>Yes, good idea!

>Cessna is backordered for that part til late January, so I'm gonna have
>to do something. For a stopgap I may just put in a standard speaker
>and hook only the gear/stall horn to it. I use headphones for my comm
>audio anyway...


I was going to ask that next: does anyone listen to comm on
a speaker anymore?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[David Lesher]

"John Clonts" > writes:



>I believe my existing speaker is 4 ohms also. At least it measures about 4 ohms with my cheap DVM-- but I know
>that's just measuring its DC resistance, how can I tell what its impedance is? (My electronics experience is
>mostly in digital!)

A) Use an impedence bridge.

B) SWAG it with a ~20 ohm pot and an audio generator. Put the pot in series and adjust it
until the voltage drop is ~equal across the speaker and pot. Shut down and measure the
pot's resistance.

Of course, the speaker impedence is nowhere near flat vs. frequency; and further, it's
never going to be close to what the label says.....

And if whatever works with a ""4 ohm"" speaker, a 8 ohm will work almost as well.


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[Mike W.]

If your speaker is like most 2-way auto speakers, the tweeter is mounted on
a little plastic 'bridge' in front of the main speaker cone. The wires that
run to the tweeter will run up the legs of the bridge. So, yes figure out
where to cut those wires and solder your wires onto those. One other thing
to look for is a capacitor connected to the tweeter, it is the 'crossover'
basically it filters out frequencies below a certain point, maybe 5000 Hz.
Keep that in the circuit with the tweeter. So with a little work you will
have two speakers in one.
If your existing speake measures near 4 ohms you should be fine. Not like a
comm has a high-current audio amp in it.

"John Clonts" > wrote in message
...
>
> Hello Mike,
>
> Mine is round, 5.25 inch. My Radio Shack is a mall outlet, no components,
but I found a speaker at-- get
> this-- Walmart!
>
> Thats a good idea about the 2 way speaker. By "electrically separate the
main cone from the tweeter", do you
> mean they will have the 4 teensy wires coming from the coils to 2
terminals on terminal strip, and I will just
> need to snip the proper ones and provide separate terminal connection to
it? I do think I could handle that!
>
> I believe my existing speaker is 4 ohms also. At least it measures about
4 ohms with my cheap DVM-- but I know
> that's just measuring its DC resistance, how can I tell what its impedance
is? (My electronics experience is
> mostly in digital!)
>
>
> Thanks!
> John
>
>

[[email protected]]

David Lesher > wrote:
: I was going to ask that next: does anyone listen to comm on
: a speaker anymore?

"WHAT? WHAT'S THAT YOU SAY? SPEAK UP"

:)

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Dave Butler]

> Mine is round, 5.25 inch. My Radio Shack is a mall outlet, no components, but I found a speaker at-- get
> this-- Walmart!

Don't ignore the advice from a previous poster about checking the magnet.
Someone put a RadioShack speaker in my ol' Cherokee once and it definitely had
an effect on the compass. I took it out and put in a genuine Piper part (or
anyway one with a weaker magnet, I don't remember any more).

[RST Engineering]

You get an audio generator and an AC voltmeter. (Be careful of the el
cheapo digital voltmeters that don't have a frequency response much above
500 Hz.) You also get a variable resistor of 25 ohms or so. You put the
generator on 1000 Hz. and adjust the resistor so that there is as much
voltage across the resistor as there is across the speaker. Remove the
resistor and read it with the dvm.

Jim


> I believe my existing speaker is 4 ohms also. At least it measures about
> 4 ohms with my cheap DVM-- but I know that's just measuring its DC
> resistance, how can I tell what its impedance is? (My electronics
> experience is mostly in digital!)
>
>
> Thanks!
> John
>