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Keith Tanner
Keith Tanner MegaDork
4/2/20 9:19 p.m.

As some might remember, I was given an old console radio and accidentally fell down a rabbit hole of embedded computing. As you do.

Short version, this is the radio on my bedside table. It plays music from my phone wirelessly.

This is our house media server and inconvenient Airplay speaker.

Well, my wife Janel spotted a vintage Philco cathedral radio while looking over my shoulder and decided she wanted one of those as an AirPlay speaker for her sewing room. Problem: they are design icons and valuable. Almost all of them have been restored and those that are in need of restoration are snapped up for parts. I didn't want to desecrate one and there was no point in paying the price. There are "modern" reproductions (that are 35 years old now) but they were just modern enough to look like something you'd buy from an ad in Road & Track. I kept looking around.

Somehow, I came across the Peerless Reproducer speaker while surfing around looking for options. That's all it is, a speaker. But it's got that great cathedral style. They're also quite cheap because they're fairly common. Well, maybe it's better to say that prices vary all over the place. Right now, eBay has them from $22.50 to $159.

I picked this one up for $12.99. The seller didn't know anything about it or if it worked, but did say it was heavy and included a picture of the unit sitting on a scale to prove it :) Since I was planning to put modern electronics in it, all I care about was that it looked to be in decent shape. It arrived today.

Here's the back - this grile is purely decorative, it's got a thick pad on the inside.

Best product name ever.

End of intro. Now let's do stuff and figure stuff out.

Keith Tanner
Keith Tanner MegaDork
4/2/20 9:28 p.m.

I wiped the case down with English Oil and it looks great. A few small bits of damage to the finish but just spots. I'll test it later to see if it's shellac (built in 1929, it's not definite) and if it is I might try to repair it.

Then I pulled the back off and the speaker looks absolutely perfect.

It's also an unpowered speaker. I thought it might be a field effect speaker like that F-63 bedside radio had, but it's a permanent magnet.  I decided to check the amperage and I could hear little scratchy noises as the multimeter put a bit of power through. Hey, maybe I can use this speaker! The problem is that it's a high amperage piece. Like 1800 Ohms. Most modern speakers are 4, 8 or 16 Ohms. That's a problem.

Solutions? I can probably wire a transformer in backwards, turning that 1800 Ohms into 16 instead of the other way around. Or maybe I can simply remove/disconnect the transformer and run the speaker directly. I'll check the impedance of the speaker in a bit. This actually has me a little excited.

Electronics will be a Pi Zero W with a HiFiBerry MiniAmp stuck on top. I should be able to put it together pretty quickly given that I've done this a few times already. Fingers crossed!

Keith Tanner
Keith Tanner MegaDork
4/3/20 12:26 a.m.

Checked the speaker without the transformer, no change. So I'll use a transformer, backwards, to turn 1800 Ohms into 8. Looks like the Hammond 146N is the right choice, and I've gotta say that "Hammond" is a good name to have involved here. Ordered.

Is this the most stereotypical magnet you've ever seen? I'm tempted to paint it red with silver ends. I think the yellow might be an anti-corrosion paint of some sort.

I also checked the finish. A bit of denatured alcohol on a rag and it softened up. That means shellac. I haven't worked with it much before, but frenchy says it's quite repairable. I'll have to get up my nerve. It looks to me like it's pretty thin, so I might have to put on a new coat.

The Pi and amp is ready, programmed and tested. Now all I need is a working speaker.

wheelsmithy (Forum Supporter)
wheelsmithy (Forum Supporter) UltraDork
4/3/20 6:33 a.m.

These builds are all great. Keep bringing style back to home entertainment.

4/3/20 5:11 p.m.

I've been looking for a busted Peerless chassis to mod into a computer case.

Color me excited to see more!

Keith Tanner
Keith Tanner MegaDork
4/11/20 12:40 a.m.

The transformer showed up. It's the cutest little thing. 

Remember that the Pi is about the size of a Hot Wheels. 

Pulled the chassis out of the case and wired it up. 2000 Ohm windings connected to speaker, 8 Ohm to the tone pack.  Success! It makes noises!


Reassembled with some new speaker cloth. I was able to glue the Pi down with some Velcro so it's both restrained and removable. The transformer is also anchored. I snuck a 5' USB cord out the bottom without any case mods and voila - an AirPlay cathedral speaker!

I did scar the paper cone when I was working on it, despite being careful. I am displeased with myself about that, but there's nothing I can do. The thing does sound fine - it's got a vintage sound for sure, with some holes in the frequency response. I could work around that with a software EQ with just a few minutes of work, but right now I have it playing the Colin James "Blue Highways" album and it's perfect for vintage style blues. I'll bet Glenn Miller or Satchmo would sound just right. 

I still want to wake up the finish a bit. I gave it a quick wipe down with denatured alcohol, which should help shellac a bit. No joy but I did lose some of the spots. Maybe another round of oil. 

RossD MegaDork
4/11/20 6:50 a.m.

Looks nice! The physical size of the transformer could be part of the frequency response issue. I know when audiophiles want huge response range, the transformers get bigger. It is not a perfect relationship, however.

dculberson (Forum Supporter)
dculberson (Forum Supporter) MegaDork
4/11/20 6:53 a.m.

I think sending the sound through a transformer will always dull the frequency response.

Keith Tanner
Keith Tanner MegaDork
4/11/20 9:13 a.m.

Well, it is an audio transformer with a published response range that covers pretty much the range of hearing at the upper end. Can't go too low but it's not a woofer anyhow. I could bypass the tone pack to see how that sounds, but I'm okay with it for now. Given that the speaker is 90 years old it's doing okay!

Keith Tanner
Keith Tanner MegaDork
4/17/20 3:11 p.m.

Update: I installed a software EQ and the speaker sounds better, but it's still a 90 year old speaker being driven with 3 Watts of power so it has an unmistakable vintage sound. It's very different from the Majestic, which has a modern 12" speaker with 60W of power driving it. Maybe I should try running it without the back panel?

But that's okay! We're using it to play acoustic jazz and some old blues and it just sounds right. 

So, next step is the finish. It's okay. Not perfect, but and with a little bit of damage. Do I dare try to restore the shellac at all? Any words of wisdom?

7/1/20 6:41 p.m.

In reply to Keith Tanner :

This looks great Keith, good job! I'm contemplating getting a non-functioning Peerless reproducer and converting it into guitar amp speaker.. basically just switching the speaker out for a new one.

However the new speaker would have to attach to the front panel.

Do you know the speaker size that's in here?

Also do you think that front panel could support the weight of a speaker (given that it'll a magnet on it too).




wvumtnbkr UberDork
7/1/20 8:57 p.m.

Leave it as is and enjoy.


Btw, there is probably a market for this type of thing...

Keith Tanner
Keith Tanner MegaDork
7/2/20 10:05 a.m.

Looks like the case is right about 9" wide inside, so there's your maximum speaker size including flange. It's been long enough now that I don't remember how thick the front panel is, but you could always attach your speaker to the steel bracket that the stock one uses.

Janel has adopted this in her home office so it's running most of the day now. Man, has it only been a couple of months since I built it?

Pete Gossett (Forum Supporter)
Pete Gossett (Forum Supporter) MegaDork
7/12/20 9:18 p.m.

In reply to Keith Tanner :

I have a friend who picked up an old Zenith tube radios & would like to getting working again. Do you have any suggestions I can point him toward for assistance. 

Keith Tanner
Keith Tanner MegaDork
7/12/20 9:20 p.m.

Unfortunately not, but there are others on the forum who know this stuff!

pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
7/13/20 7:04 a.m.

Pete:  I don't know that they're going to be the last place to look, but the Parts Express forum is where I would ask.  They probably have some folks that either know "the best" forum for such things or have folks there that would be helpful directly.  The Parts Express company may also have hardware needed to get the Zenith rig going well again. 

Pete Gossett (Forum Supporter)
Pete Gossett (Forum Supporter) MegaDork
7/13/20 3:39 p.m.

In reply to pres589 (djronnebaum) :


Mr_Asa Dork
7/13/20 3:50 p.m.

Hey Keith, Dad is a professional antique furniture restoration guy.  Trained at the Smithsonian and worked at Colonial Williamsburg for a little while.  If you want I can ask him if he has any tips for working with and bringing back the finish.

Keith Tanner
Keith Tanner MegaDork
7/13/20 11:29 p.m.

I am all ears, although it does seem to wear the wear well. I do have a water ring in the top of the GE F-63 that I'd like to sort out. 

Mr_Asa Dork
7/14/20 11:13 p.m.

Quick digression in order to explain something that you may not be familiar with. 

I sent Dad an email asking for tips, he wanted to know how you had determined if it was shellac and I mentioned the alcohol test and then asked if you needed to find a blacklight.  I also sent him a link to the thread.  I'm basically going to just copy his email here, but I wanted to quickly address the blacklight mentioned; certain materials glow under blacklight and they glow different colors, its a nice non-destructive test to determine what you are messing with.


First, tell Keith to lay off with the oil; at best, it has a mineral oil base, which will need to be soaked with naphtha to remove it before he can repair the finish.  At worst, it'll be a drying oil, pressed from seed or nut - linseed, flax, tung, even walnut.  All drying oils will ultimately oxidize, saponify, turn black and absorb moisture.  Drying oils can only be removed with solvents that can affect the original finish, or with an expensive enzyme solution.

He did say that he tested it with alcohol, and removed some of the finish - that's promising.  But it still could be a factory varnish; most of those have very poor aging characteristics.

Yes, a blacklight will go a long way toward characterizing the finish.  But it needs to emit in the 362 nm frequency; the excitation frequency determines the visible light emitted when it fluoresces.  The ones I use take a 11 1/4" bulb - (sorry, I just brought it inside, can't read the number, it's worn off.)  Shellac shows as orange, one of the few natural resins that do; another is Dragon's Blood resin, used in the 8th century to give a deep red color.  On something that old, the finish may have oxidized and the surface will be "quenched" won't fluoresce.  Tell him to check the spot he cleaned with alcohol, it will have exposed the un-aged varnish.

Once he has an idea what coating he's dealing with, we can go on about repairing it.  Tell him my credentials: graduate, Smithsonian Furniture Conservation, class of 1993.  I especially enjoyed repairing antique finishes.  He'll want a copy of "The French Polisher's Manual" ISBN 0-918036-05-4  And if it is shellac, he'll want to find some shellac flakes, dissolve his own.  The shellac you can buy in a can is too old before you even open it.

Keith Tanner
Keith Tanner MegaDork
7/15/20 8:54 p.m.

Excellent stuff. I'm going to end up learning something here, aren't I?

I never oiled the GE, so no worry there. I used to have a real UV light that was used for etching circuit boards, but that was 20 years ago. I will source one with the correct wavelength range. This will be interesting. 

Mr_Asa Dork
7/15/20 9:00 p.m.

Yeah, definitely going to learn something if you follow Dad's instruction path.  He is not one to take shortcuts in most things, so he'll likely be giving the full breakdown of the most correct museum-quality way to do this.  Cousin Eddie, before he left, reminded me of Dad's meticulousness when it comes to restoring and rebuilding something.

You learg the darndest things on GRM.

Pete Gossett (Forum Supporter)
Pete Gossett (Forum Supporter) MegaDork
7/17/20 8:30 a.m.

In reply to Mr_Asa :

I want to hang out with your dad & I have no desire to delve into antique furniture restoration/conservation myself. But it sure is fascinating reading his reply!

Asas_Dad New Reader
10/26/20 6:18 p.m.

In reply to Pete Gossett (Forum Supporter) :


I sent this to my son Asa some time ago, but he's been some busy; he's in the final semester of his Bachelor's in engineering.  So I registered to pass along what I can.  I left the text the way I wrote it a few months ago.

Just checked in on the GRM thread; please pass on two corrections: When I said that Dragon's Blood was used in the 8th Century, that should have been 18th C.  Numerals 1 thru 4 and their attendant Shift characters on my keyboard seem to have taken what the troops in the 19th C. West called "French leave". Meaning AWOL, UA.

I have found no evidence that shellac was commonly known or used before the 18th century. Earlier finishes in the west (Europe and the Americas) tended to be beeswax, linseed oil, or perhaps colophony - crystallized pine sap dissolved in turpentine, or "run" - melted in oil. The 18th C, what with the opening of regular trade with the Orient and the Americas, was one of furniture makers search for the perfect "blonde" finish - that is, one that didn't impart a color to the wood, but gave a durable (relatively) coating.

That brings me to the second correction, which is really more of a clarification. When I said "factory varnish", I referred to natural resin mixes made up by businesses in the last three decades of the 19th C., that were trying to produce a perfectly blonde finish that they could put in a can, to sell. All were spirit-soluble (in alcohol). They were universally the damnedest concoctions that you could imagine - fossilized Baltic amber melted in oil, semi-fossilized resins from Copal and Kauri trees from Africa, Australia, many more resins from South America. But it was all stovetop cookery, based on each individual resin's perceived characteristics. I'm sure they looked nice when they were fresh, but all ultimately failed due to their chemistry. When you see a severely crackled, black finish on an antique, even pilled (drawn up in islands), it is a late 19th C finish. And the varnish factories kept producing this stuff into the 20th C, perhaps as late as the 1940s. I have worked on antique furniture in one 1840s historic house here, all pieces had a poor later varnish over the original; I'm convinced that the house owner had a workman with a 5-gallon bucket of the stuff that he slathered over the original coating. It was common practice; finish looking tired, worn? Slap some more over it, improve the optical density - for a little while. In this house, the workman didn't even clean the soot from the coal grates off the original finish first.

I digress. Tell Keith to look online for shellac flakes. Here is just one:https://www.shellacshack.com/purchase-shellac-flakes.html He'll probably want to buy a color that matches the present coating. He can dissolve it in Everclear or some other grain ethanol. Yes, he can use denatured alcohol from Lowe's or HDepot, but the denaturant in them is usually methanol, wood alcohol, which will migrate through rubber, latex and nitrile gloves and your skin, and can damage your optic nerve and liver. And he'll want to keep the dissolved flakes in a dark bottle to retard light-aging; I use brown or green 16oz Grolsch beer bottles. 

Next, we'll talk about how to clean that original finish without damaging it.  Keith, did you ever find a blacklight?  -Dad

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