Help with identifying CL freebie find!

bigskycntry

New Member
The only markings are as shown:

"Coal TD3" on the front panel
"Polydax" on the midrange
"Polydax" on the crossover warranty deal which is stuck across the XO and bottom of the box such that if the XO is removed the seal will break.

The woofer is stamped "Made in the USA" and the tweeter is TAIWAN ROC albeit of a very high build quality.

The mids have a large sealed back cavity and one of them needs new foam. Any tips on where I can find flat open cell foam to refoam these?

The gentleman who gave them to me is a retired doctor who to the best of his recollection paid around $1,800.00 for them in the mid seventies while he was in college - he can't remember if "Coal" was a model or the manufacturer. Based on component quality I believe his quoted price which puts these speakers in the roughly $8-10,000.00 price point in 2018 dollars depending on when in the seventies he purchased them.

I'm going to rebuild the XOs and refoam the mids. One woofer had two minor cracks in the surround that were easily repaired with elastomeric sealant but will probably have those refoamed eventually too. The XOs and all voice coils check out OK on the DMM and the one speaker with 3 working drivers sounds amazing - better than my B&W DM 603s did.

Also having done my share of woodworking these were definitely hand built one at a time.
 

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Bump... pretty sure the woofers are Bextrene and look to be hand made by the molding marks.

Also the dust cap is connected to the pole piece directly not to the cone so it doesn't move. More of a dust plug.
 
I have no idea what company made these but you're absolutely right in that they used quality parts and the cabinets appear to be well made as well.
I hope that you're able to get them back up and running and enjoy them. Keep us posted. :)
 
I have no idea what company made these but you're absolutely right in that they used quality parts and the cabinets appear to be well made as well.
I hope that you're able to get them back up and running and enjoy them. Keep us posted. :)

If you have any idea where I can find a flat foam kit that glues to the underside of the speaker that would be a great start. As an engineer I always assume the person who built something knew what they were doing so I would prefer to repair to OEM spec if I can.

The XOs are glued down with some sort of elastomeric adhesive. Still trying to figure out how to pry them out of the bottom without damage.

Have Auricap paper in oil and dynamicap in film on hand in the correct values, leaving only a high quality axial electrolytic on the items needed list once I pop them out.

Too many inductors to think about foil ($$$$$$$) so I'll probably just recap, line the box with foam, and refoam the mids and they will serve many more years of duty in my study.

Any tips on sources for flat open cell foam precut?
 
I'd bet a doughnut that those speakers were named something other than "coal". There is either a piece of the nameplate missing or damaged.
Good to see you're treating them right. Maybe, one of the bigger speaker repair houses like Orange County Speaker, Simply speakers, etc. can get you in touch with some flat foam. McMaster-Carr may sell it, I dunno. Good luck with the new speakers!
 
I'd bet a doughnut that those speakers were named something other than "coal". There is either a piece of the nameplate missing or damaged.
Good to see you're treating them right. Maybe, one of the bigger speaker repair houses like Orange County Speaker, Simply speakers, etc. can get you in touch with some flat foam. McMaster-Carr may sell it, I dunno. Good luck with the new speakers!

I think that you are most likely right as the other speaker is missing its name plate entirely. I found the foam in flat sheets and worse come to worse I'll figure out how to redneck cutting it - rather get a purpose cut kit though. I've got an email into Simply Speakers to see if they can supply a flat version to size.

I'm fiercely curious what brand these are but mostly the working one sounds sweet so I want to make them "new" again.

If I have to I'll send the mids to a speaker rebuilder but with a baby 8 weeks out a refoam is much more budget friendly. :)
 
Probably - similar ones made by Polydax/Audax these may have been a replacement for the originals. Audax sold ones that look identical that were used in several KEF speakers.

https://goo.gl/images/Y4RpkU

That's an Audax TW51/TW74 and most definitely not what you have in your speakers. It is a tiny tweeter, the voice-coil diameter is ~10.5mm.

2970801_orig.png
 
That's an Audax TW51/TW74 and most definitely not what you have in your speakers. It is a tiny tweeter, the voice-coil diameter is ~10.5mm.

I am in total agreement what I was saying is that I thought those Audax units were most likely the originals and these Pioneers were replacements. I think that may be the case as the other two Polydax drivers have a DCR of 5.8ohms vs. the 8ohm DCR of the Pioneer replacements. The external dimensions of the pioneer are identical to the square flanged Audax/Polydax tweets (including the titanium super tweet) so I have no idea exactly which tweet was the original other than it also had a DCR of 5.8 ohms based on the XO cap/inductor values, fit into the same sized hole, and I posited the use of the above TW51/TW74 (or similar) because they are nearly identical to the Pioneers visually including the foam ring around the tweeter dome to help control dispersion. Thank you for that data sheet too btw couldn't find dimensions of the speaker - you are right its too small for the mounting flange. However the bigger square Audax are an exact match to cutout size and screw placement.

That's one of the reasons I am trying to figure out the OG manufacturer of this speaker. From what I can tell the original speaker used 100% Audax/Polydax drivers each of which had a DCR of 5.8ohms. Also the woofer (based on PN) is an Audax unit as well the "made in USA" is due to this driver being assembled here in the US under license.

Here are the exact replacement Audax units for the woofer drivers in my speaker albeit this is the French made version of the same speaker:

https://www.ebay.com/itm/NOS-1pair-...728019?hash=item2a9adbe253:g:jYQAAOSwEzxYYasl

Long and short of it is if you have better suggestions as to which Audax tweet may have been in this unit originally I would be super excited to take a look as I need to find a 5.8ohm Audax/Polydax tweet to replace the originals. The current woofers are in great shape other than a new surround being in the cards at some point (still OK but showing signs of age) and I have a call in to theloudspeakerstore.com as previously suggested to get the mids refoamed.

I want to pull them back to as original as possible which may take some guesswork if the manufacturer cannot be identified. Any tips on 5.8ohm (or 6 ohm) Audax tweets with the same physical configuration? I am pretty sure it is not the titanium bullet tweeter as they were not around in the time frame these were made (early to mid seventies).

Thanks for all the input!
 
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