M14s: I may have a pair

**Alien_Shore** · July 5th, 2012, 08:44 PM

I wish Earl was still around. I'd love to pick his brain about what makes those designs so good. Not to mention, I'm wondering about those old inductors they used...I am definitely going to test some variations around using original coils, new caps/ new inductors, new caps/ etc. I put together the schematic for my M14 crossovers this evening for giggles.

I should have my L/C built by next week sometime, then I can confirm the inductance values of all the coils.

**voice of the theater** · July 5th, 2012, 09:56 PM

Originally Posted by Alien_Shore

I wish Earl was still around.....

Do you mean Earl K?

**aditya** · July 5th, 2012, 11:04 PM

Yes, I am also asking the same.

Do you mean Earl K ?

**Altec Best** · July 6th, 2012, 07:49 AM

IIRC Earl's (Earl K) work takes him out of town for long periods quite a bit.But he doesn't post here that often anyway.He posts more frequently over at Lansing Heritage.

**aditya** · July 6th, 2012, 12:59 PM

Many thanks AB for the clarification.......

**aditya** · July 6th, 2012, 01:53 PM

Originally Posted by Alien_Shore

..........I'm wondering about those old inductors they used...I am definitely going to test some variations around using original coils, new caps/ new inductors, new caps/ etc............

It is really nice to see that so quickly you have started to suspect ( rather appreciate ) these old inductors. I will tell you (and everybody else) not to lose these,and to preserve them, as these inductors were part of a 30/40 yr old design frequency-shaping circuit. It wil be very difficult to duplicate them today. Inductors used in the mains ckts are not important, as they can be easily duplicated, but not these.

I remember reading a small story in the late 80's/early 90's issues of the "studio sound" magazine. It was about the famous API-550A equalizers, which used a simple two stage transistor amplifier with the output being loaded with a trafo, from which the feedbacks were taken for the frequency shaping purposes, via a muti-way switch. As API was closing/closed due to financial troubles, somebody (he was a big tech head of that time) wanted to replace the existing 550A circuitary with more modern high end components, (as the 550A innards were very clumsy and dirty looking) and continue selling them. But they never succeeded, even after trying it for two yrs., and the original output trafo could not be duplicated. They just could not duplicate the sonic quality of the original 550 equalizer.

**Alien_Shore** · July 6th, 2012, 07:14 PM

Yes, I meant Earl K, the crossover wizard.
I recently picked up a pair of crossovers that were parted out of a pair of 9842s. I think what I'll do is use them for the components and work on some tests.
At this point, I doubt that the M14s can be improved upon, short of driver refubs and replacing oxidized caps in the stock XO design. I have done a TON of reading on this, and it is still amazing to me that so little is published about how these XO designs truly work. It is apparent to my old, rusty ears though that the entire package was very carefully designed to work together. If only such dedicated engineering and manufacturing still existed.

**Altec Best** · July 6th, 2012, 07:22 PM

Originally Posted by Alien_Shore

If only such dedicated engineering and manufacturing still existed.

It does ! You just have to pay a ton of money for it these days....

**Alien_Shore** · July 6th, 2012, 10:23 PM

Managed to squeeze in another bit of testing this evening before dinner:

the 902 in the left side is definitely lacking. So I put a 908-8A on there with a spare horn. MAGIC.
Now to just figure out how to fit that sucker into the cabinet