Speakers

[cmsusllc]

Has anybody found anything other than the factory replacement speaker? I've ripped out the old headliner and am trying to clean up the mess. The four tank vent hoses have been replaced and i'm cleaning up all the old glue where several someones have tried to insulate. The orriginal speaker obviously hasn't worked for a long time as there was no paper cone left. I don't use it but would like to have it for backup, also need to pick up a mike to store in the glove box.
Thanks Scott 53B

[GAHorn]

Not only is it a good idea to have a hand-microphone for backup in case of a failed headset, many aircraft operations REQUIRE it. And you should have a seperate jack for that microphone, as well, hopefully that completely bypasses the audio/amplifier-panel.

The "factory speaker" has a mounting-feature included in it 's construction which facilitates replacement. The original speaker uses the upper cabin skin and screws to mount the speaker frame directly to the roof. Aftermarket speakers do not and can be very difficult to mount for that reason.

Here's a bit of info many do not know: Speakers can be RE-BUILT. Many, qualified stereo repair shops can "re-cone" speakers very inexpensively. This involves salvageing the speaker magnet, mounting-frame, coils, etc.., and replacing the paper cones with identical paper, or even upgrading them to poly or marinized (waterproof) cones. This returns the speaker to "like new" condition and typically costs less than $25....which is a bargain when you've been frustrated by attempting to mount a different speaker which does not have that mounting-to-the-cabin-roof capability.

So...TREAT THAT OLD SPEAKER GENTLY AND PRESERVE IT AS AN INTACT UNIT if you plan to rebuild it. Do not damage the cone anymore than it is already, and protect the wires, coils, and magnet.

Also, keep in mind that a speaker is an important safety feature for the times your headset and/or headset circuit fails. Make certain that comm radios you install can actually DRIVE a speaker...or plan on also installing an audio amplifier which can do so. (Many less-expensive radios cannot supply adequate volume to a speaker without an external audio amplifier. All Narcos can, but many other popular brands cannot. Check with your avionics dealer when you plan to replace radios.)

[cessna170bdriver]

About 1984, my cabin speaker quit working, and I found the culprit, a mouse, dead in the headliner in a pile of chips of what had once been the speaker cone. I went to one of my many junk boxes and found a speaker of similar size that had once been part of a home 8-track system I'd had as a teenager. To facilitate mounting, I glued a 3/4" thick maple block to the magnet frame of the speaker, and attached it to the cabin roof using wood screws (through the original holes), finish washers and a couple of dabs of RTV. Still going strong in 2009.

Miles

[jrenwick]

About 1984, my cabin speaker quit working, and I found the culprit, a mouse, dead in the headliner in a pile of chips of what had once been the speaker cone. I went to one of my many junk boxes and found a speaker of similar size that had once been part of a home 8-track system I'd had as a teenager. To facilitate mounting, I glued a 3/4" thick maple block to the magnet frame of the speaker, and attached it to the cabin roof using wood screws (through the original holes), finish washers and a couple of dabs of RTV. Still going strong in 2009.

Miles

Need to be careful about substituting any old audio speaker into an airplane. Some of them have magnets strong enough to mess up the compass. (Not saying yours did, Miles, but just something to be aware of.)

John

[cessna170bdriver]

Need to be careful about substituting any old audio speaker into an airplane. Some of them have magnets strong enough to mess up the compass. (Not saying yours did, Miles, but just something to be aware of.)

John

Agreed. You need to reswing your compass after any electrical modification. Also, be careful about placing a portable GPS on the glareshield if your compass is in that vicinity. My compass is on the glareshield, and I have to place my 296 over by the door post to prevent a 20-degree swing.

Miles

[jrenwick]

I agree the compass needs to be swung after a speaker replacement. But the different point I was trying to make was that some of the consumer stereo speakers on the market have permanent magnets so strong that you might not even be able to compensate for them. I think a lot of people aren't aware of that.

John

[GAHorn]

Audio quality can also suffer do to different ohms of an aircraft speaker (typically 4 ohms) and the common stereo-type speakers (Typically 8 ohms.)

[cessna170bdriver]

I agree the compass needs to be swung after a speaker replacement. But the different point I was trying to make was that some of the consumer stereo speakers on the market have permanent magnets so strong that you might not even be able to compensate for them. I think a lot of people aren't aware of that.

John

That's what I was implying, too, and should have stated more clearly. You wouldn't really know whether the magnets were too strong until you installed a speaker (at least temporarily) and tried to re swing the compass. If you can't re-swing the compass, don't use that speaker. That's not as likely to be a problem though with the 1970's-vintage speaker I used (still using, as a matter of fact). I wouldn't recommend buying a non-aviation rated speaker specifically for this purpose, but if you have an old speaker laying around that will fit the space, it's worth a try.

Audio quality can also suffer do to different ohms of an aircraft speaker (typically 4 ohms) and the common stereo-type speakers (Typically 8 ohms.)

Thats possible, but many amplifiers will drive both 4-ohm and 8-ohm speakers. My KMA64 audio panel is rated to drive 6 Watts into an 8-ohm speaker, and 4 Watts into a 4-ohm speaker. A different audio panel, the KMA64H, has both 4-ohm and 8-ohm taps and can drive the same power into either speaker impedance. Check the specs on whatever radio or audio panel you'll be driving it with. Again, worth a try if you have one laying around.

I'm no audiophile, but my setup is still clearly audible after 25 years. (And yes, I do use the overhead speaker and my hand-held mic on occasion, such as immediately after an annual inspection, when due to a brain f*** I might find myself without a head set in the airplane.)

Miles

[mit]

I bought a replacement speaker from Cessna used a piece of I think 3/4" Alum screwed to speaker and drilled and tapped for installation through the cabin skin. That was in about 92-93.

[cmsusllc]

George, I had no idea a speaker could be reconed. I do have the mike jack and want to fix the spesker for backup pourposes, that's why I'm a askin. Someone had mounted another one above the door frame, it was blown too and was a shoddy instal. I'll try to find a repair shop that can do the recone.
Thanks Scott

[mrpibb]

I replaced my speaker about 4 years ago, I replaced it with a quam 4" 8 ohm. The price was right as it is used on the jet airliners, Chief has them for around $20. The basket wasnt as deep so we made a bracket to mount the magnet to the cabin top, and as far as the magnet size it was smaller than the one that came out although you really cant tell the strenght of the magnet according to its relavent size. I also keep a hand mike in the glove box for those days I like to fly hearing airplane noises, I also added a switch to turn off the speaker for when it is not needed.

[GAHorn]

George, I had no idea a speaker could be reconed. I do have the mike jack and want to fix the spesker for backup pourposes, that's why I'm a askin. Someone had mounted another one above the door frame, it was blown too and was a shoddy instal. I'll try to find a repair shop that can do the recone.
Thanks Scott

Shop around for price. I"ve had several stereo speakers re-coned and the price varies considerably. (One of my 18" large woofers was re-coned for $18 and two years later when the old-guy retired his competitor charged me $35 for the identical twin. Then a year later I found another shop who would do them for $15 regardless of size.) I think I could do it myself if I had the material. All they did was support the coil-center in-place with strips of paper stuck down in the air-shaft (to prevent it's shifting and ending up in-contact with the guide-magnet) while they glued a new cone in-place to the old coil. The outer-rim of the cone is then attached via an overlying gasket which is glued to the frame. Some speakers have a circular foam strip that attaches them to the frame in lieu of a gasket. Clear shellac-type glue is used. I wouldn't do it for $15 tho'. It takes a good 20-30 minutes to perform the job, and materials alone are probably about $15.

If you have your re-coned, ask if they can use poly (plastic) or "marine-grade" cone material. There may be a price difference but they'll last 100 years instead of 20, and I'd hate for you to ever have to do it again.

[cmsusllc]

I finally had mine reconed, well basically rebuilt. A new one would have been cheaper but I have the orriginal mounting with no need for modifications.
Around The Sound --- loudspeaker reconing. 323 N. 105th St. C Seattle, Wa. 98133 206-782-7975
It looks brand new. Basic recone -- $31.00 plus tax. Mine was $41.00 with a new voice coil, new gasket and regluing the magnet along with the recone. They stated that Qualm Nichals might be a source for replacements, although there would probably be need for modification.
Scott --- 53B