M14s: I may have a pair

[voice of the theater]

The drivers do appear to be all original equipment. The woofers are the usual suspects: cast frame RCA 34633. The compression drivers are the OEM 902 ferrite units.

As VOTT says, the woofers would be expected to be refoamed, and indeed that appears to be true. I think they were done professionally, it looks to be very good work on both woofers. Some pro sound shop in NYC must have done them, as they put their stickers on there. Good news is that original cones and VCs appear to remain in place and look to be in great shape. Can someone with original drivers let me know what the cone number is?

Both woofers sound good. One VC shows a DCR of 8.0, the other 4.0

The HF drivers both show good DCR. As mentioned, they are the OEM 902s with no back cover and the loading caps. On one of them, I heard the tell-tale occasional buzzing sound and upon inspection the phase plug is loose. I suppose I will need to do a little research on how to shim it and glue it down. Maybe remove the loading caps and replace with felt while I'm at it?

I just went through my photos of my Model 14 woofers and none of them showed the cone number So I pulled both of them and took a few new photos. It looks like we have different cone numbers. I always assumed mine had the original cones, but you know what they say about when you assume. Anyone else out there know which of these are original cone numbers? Or did Altec change cone numbers during production and both pair have original cones (mine are from 1981 and Mike's are from 1980). Mike, you mentioned one of your woofers has a DCR of 8.0, the other 4.0. That is unexpected. Do they both have the same cone number or does the cone with the different dust cap glue also have a different cone number? (my two woofers have matching cone numbers as seen in pics below) BTW, as Altec Best alluded to, reconed woofers are not a problem IMHO if they were reconed by GPA (or by a pro using GPA kits) since their cones are built to Altec spec......

[Alien_Shore]

Thanks for the pics, VOTT.
I spent a bit of time looking around on the web today, and I think you probably have original cones. I suspect mine are replacements, and probably not GPA. As far as the DCR on the one woofer being low, I agree it is concerning. I may give Bill H a call and see what he wants to just recone them, since the wierd DCR probably indicates a problem with the VC.

I did some further inspection tonight, looking at the HF drivers, and the crossovers. Here are some more pics:

I think this is the 902 8A?


Here you can see the loading cap is cracked. It had a bad bolt on it, which was overtightened




Phase plug on this one is still glued down tight


But VC and phram look fine...looks like the original lightweight ones


The crossover unit looks like it needs some work. I suspect those caps are not what they used to be after 33 years...


A fun project to fix these up and get them in like-new listening shape!

[voice of the theater]

Thanks for the pics, VOTT.
I spent a bit of time looking around on the web today, and I think you probably have original cones. I suspect mine are replacements, and probably not GPA. As far as the DCR on the one woofer being low, I agree it is concerning. I may give Bill H a call and see what he wants to just recone them, since the wierd DCR probably indicates a problem with the VC.

I agree-mine look like an original Altec cone number (format). Well worth having GPA re-cone yours. They'll be as good as new/up to original Altec spec.

But VC and phram look fine...looks like the original lightweight ones

Those do look like the original diaphragms--same original diaphragms that my 902-8A's came with. They are 34647 diaphragms, not the lightweight ones.

The crossover unit looks like it needs some work. I suspect those caps are not what they used to be after 33 years...

I would definitely re-cap the crossovers. I did mine with Solen "fast caps" (recommended by GPA) and they dramatically improved the sound quality..... Somewhere on this forum there is a thread about my Model 14 crossover recap--with pics, etc.....

[Alien_Shore]

Those do look like the original diaphragms--same original diaphragms that my 902-8A's came with. They are 34647 diaphragms, not the lightweight ones. I would definitely re-cap the crossovers. I did mine with Solen "fast caps" (recommended by GPA) and they dramatically improved the sound quality..... Somewhere on this forum there is a thread about my Model 14 crossover recap--with pics, etc.....

I'm curious, what is the part number for those "lightweight" frams? All the doc that I can find only mentions 34647 as the replacement part for 902s...

Also, has anyone done an A/B compare of the GPA 902 and the 902 with the original lightweight fram?

[voice of the theater]

I'm curious, what is the part number for those "lightweight" frams? All the doc that I can find only mentions 34647 as the replacement part for 902s...

Also, has anyone done an A/B compare of the GPA 902 and the 902 with the original lightweight fram?

The vast majority of 902-8A's were originally equipped with Altec 34647 diaphragms. That was the original "stock" part for those drivers. It's the same 34647 diaphragm that GPA manufactures today. So your drivers do appear to have their original diaphragms still installed (same as mine). From what I've heard, some of the very first 902-8A's may have come with the "light" diaphragm that was the "stock" diaphragm for the 802-8G drivers. That was an Altec 23744 diaphragm.

[Alien_Shore]

I've been busy with a bunch of other stuff, but here's a teaser of my messy desk. My Model-14 refurb project is still alive.

[Alien_Shore]

OK, the first prototype is complete.



This is a modified version of the Richard C Model 14 crossover with zobel on the LF side.

Gonna go upstairs and do an A/B comparison to the stock XO.