In my quest to put both of the 1940 and 1942 Zenith Numerical Parts Lists into Excel spreadsheet form using Optical Character Recognition (OCR), I realized that there are several vendor codes used for Zenith loudspeakers prior to World War II. I know that Zenith employed both Jensen and Utah speakers. I believe these were denoted by the X and U codes respectively, but I could be wrong. There were obvously some other manufacturers that supplied speakers to Zenith.

There are several vendor codes used on the pre WWII Zenith radios:
AB -- (Example: 49AB186; 49-208AB )
ABX
AF
AG
BP
H
U
X
And possibly others. I have included some photos of the different types.
Maybe some of you forum members can identify the manufacturer of these speakers? Comparison with those used in other brandsof radios may be helpful:
1)49-208AB
2)49U397
3)49H416
4)49-49X
5)49-121AB
6)49ABX241

After World War II, RMA-EIA codes show that Zenith manufactured most of their own loudspeaker employed in their radio models.

Hi Martin, would this apply to the speakers used in the transoceanics?

BTW, thanks for the 8G005 data you sent to me.

Shawn: concerning Transoceanics, it would apply only to the 7G605, since all of the post-war T-Os that I have seen use the "343" RETMA (RMA-EIA manufacturer codes) code which denotes Zenith. I believe the RMA codes were instituted during WWII, since I have never been able to find any on pre-WWII sets.

BTW, my 7G605 loudspeaker has the part number 49BU509. This "BU" is one I missed in the above list.

Martin, I was told by one of the Detrola engineers that I interviewed extensively in the early 1990's that Operadio in St Charles IL was one of, if not the major speaker supplier to Zenith in the pre-war years. When Detrola purchased Utah in the 40's, one of their engineers came to the Detrola factory and set them up to manufacture speakers on site. I suspect that gentleman may have been the source of the Operadio-Zenith information since he came to Utah from Operadio at some time previously.

I was under the impression that the AB code indicated Operadio. Any way to verify this? Later Operadio became DuKane, the EIA/RMA number was 252.

Apparently you do not have the list relating each Zenith parts vendor to the alphabetic code?

I think its interesting where Zenith painted some of their speakers gold and some silver in the same radio model .

There were plenty of speaker manufacturers in and around Chicago in the thirties. A 1939 list I have includes: Ariston, Arlab, Consolidated, Electronics Design, Gibbs, Operadio, Oxford, Quam/Nichols, Radio Speakers, Utah and Webster.

Mr. Detrola wrote:


Interesting possibility. The only way right now that I can think of to verify this is to search for Operadio speakers used in other brands of radios and compare to ABs used in Zeniths. Initially, I thought AB might have been Allen-Bradley, but I do not think that Milwaukee based company built loudspeakers. However, Allen-Bradley built some fine potentiometers (volume controls, etc) and resistors. The controls used in the 1000Z Stratosphere are Allen-Bradley produced.

In the meantime, I may try to see if any of my immediately post-war Zeniths have any AB code speakers in them.

Aha! no AB yet, but I found AG, which is manufacturer code 277 (Emerson). This was a speaker in model 4K035 (part number B49AG450, EIA/RMA code 277603, manufactured the 3rd week of 1946).

Thanks for the information. I notice that on the 1930 models for the 50/60/70 series that Zenith used Oxford, Magnavox, and Symington speakers (all stock # 49-27).


Martin

No. 2 has "U" in the part # and has the classic Utah field coil pot construction.

On the third picture, my vote will be Utah.

No.4 resembles the (E.H.) Scott tweeters I have. My SWAG on them would be Jensen.

I wonder if Wright-DeCoater was an ther suppler to Zenith.

Permo-Flux speakers were also a possibliity. Cinaudagraph, too.

I think that the "14 inch" speakers were Magnavox. These were the 14 inch frame with a 12 inch cone. Philco used them on some sets, too.

Did Carbonneau, in Grand Rapids, Mich. supply Zenith, I wonder??

jkaetzjr, the "U" designation I also thought was Utah. What I have since found points to Rola:


The above image is one I just took of my Zenith model 811. It has the Rola speaker with the Zenith 49-93 part number stamped on the frame. Also, on a post-war Zenith speaker I just discovered that it has the Zenith part number 49U512, with the RMA/EIA manufacturer code for Rola: 285641 (285=Rola; 641 is the date code)

My Zenith 985 has a Rola tweeter installed in it (p/n 49-107U):

Note the similarities between this and the 49-93?

Below is a Jensen speaker that I found in my Belmont 777C Skyrover. The Jensen sticker appears washed-out in this photo. Note the similarities in the frame with the earlier Rola speakers. Also, take note of the difference in the field coil yoke:


Every speaker pictured in the message is either a 5" or 6" size.

The speakers in my 440 have paper labels with lots of patent numbers; I looked up the last one (1,698,374) which was assigned to Utah.

Another vendor code I did not see on the list is 'B'. I have a 10S668 here with a 49B416 speaker in it. BTW, this speaker has not been painted gold. It does look similiar to the more common 49H416, but the basket has a slightly different shape.

Ed

I don't know if this is any help at all but I have two different brand radios just back from the fixer-guy and both have a tweeter and interestingly the tweeters seem to be identical.

One is from a Zenith 12U-159 and the tweeter is marked 49-158AB and the other is a 18-38 Midwest with no markings except a small number S375A stamped on the outer rim.

Both speakers appear to be identical in stamping, size, mounting holes etc. The only differences are the Zenith has a screw on the back of the metal cone and the Midwest does not have that screw and they are painted different colors.

Here is what we have so far:

AB -- ? I would like to discover the manufacturer here, since so many Zenith speakers before WWII were AB produced.
ABX -- ?
AF -- ?
AG – Emerson (277 mfr code on one postwar Zenith model 4K035 B49AG450)
B -- ?
BP -- ?
H – Utah. The early speakers such as 49-53 and 49-62 employed the H code and both were available in the parts catalogs with the H designation.
U – Rola (285 mfr code on two postwar Zenith model 6G001YX 49U512).
X - Jensen. From part numbers in the 1940 P1 parts catalog for Zenith.

Maybe the big unknown vendors might include Magnavox and/or Oxford? Some of the codes would appear to be a combination (ex: ABX).

Thanks Bruce, Ed, Alan, Doug, Ken. Maybe somebody can uncover a smoking gun. I liked Alan's patent angle. I may have to go see if any of these speaker companies held any design patents on their frames.

Ed, I noticed the same gray colored speakers in the 1942 8- and 10-tube models. The 10S668 was a cabinet original made to be a stepped down version of the one used on the 12H670. This was done originally to promote an FM set having a 10-tube chassis, but it obviously was changed to a late "concentration" model to help move 10-tube chassis in a price bracket just below the very common 10S669.

Ken, the paint was probably done at the vendor. Just a guess, but I think that is why the 49-208 used in the 6S254 console were supplied from either of two vendors: U (Rola) or X (Jensen).

Ahh! Bringing back this thread as I'm trying to solve the puzzle too.

Who was AB?

I figured out X = Jensen and H = Utah, but now I can add U = Rola to the list

Hopefully the puzzle can be solved.

-Steve

It doesn't look like Martin has been here for about a month. I was going to ask him about these and the other Zenith files and if they were accessible.

Yeah, he never responded to an e-mail I sent a month ago. I hope he is ok.

-Steve

Sorry about being away for sometime guys. The first thing was a bad car wreck in a construction zone at the end of March. I was hit from behind going to work at 5:45 AM after I stopped due to a surprise construction zone 'lane change' made during the night. My car was totaled. The deputy who responded was on his way to the construction zone because another driver shortly before me called 911 because the road cones weren't right and that somebody might get hurt. Even worse was that this was followed in mid-April by some serious family medical issues that cropped up.

Getting back to the discussion, I am not sure which manufacturer is denoted by 'AB'. I do know that 'CZ' is certainly Zenith, as Zenith set up its own loudspeaker production line, possibly as a result of the difficulty encountered during 'reconversion' to civilian radio production just after the end of WWII, not to mention union strikes, OPA price controls, etc.

We should be able to figure out which is which by latching onto some 1930s and 1940s speaker catalogs, and then compare speaker frames, yokes, and other speaker parts between catalog photos and actual Zenith speakers.

I have no smoking guns listing which manufacturer is which, but the Zenith 1940 and 1942 parts lists do list quite a few speaker manufacturer codes...

Wow, Marty, I hope you weren't injured...
Also hope all medical issues are improving.

No worries on the response to e-mails, just as long as you're ok.

Yes, in the Volume 2 Zenith manual I have, it does show speaker codes, but nothing to identify the manufacturer.

As I can, I will try some comparisons to known speakers. It would be great to crack these codes!

-Steve

After looking in the Carron parts book I think AB is Operaradio, and AF is Radio Speaker Co. I also came up with Radio Speaker Co as AG.