altec 1220 mixer, reverb tank...

[pucho812]

So a friend calls me up saying he just got a  altec 1220 mixer, would I have time to look at it saying it doesn't work correctly. When using the internal reverb he doesn't get any reverb. I check/tech it out and it is missing the Spring reverb tank. I guess the previous owner removed it? Can anyone suggest a replacement tank?

 

[RuudNL]

Have a look at the Accutronics/Belton product line.
http://www.accutronicsreverb.com/

 

[pucho812]

yes, acutronics was/is my first choice. They are used in fender amps and I have used them in amp builds before.  I was more asking of the specs as to match to closely to the original.  Not all reverb tanks have the same in and out Ω and the altec user manual doesn't have those specs listed.

 

[RuudNL]

The most common ones are low-Z in, high-Z out.
If you don't have a schematic diagram, isn't it possible to have a look at the driver circuit?
The driver chip (or output transistors, or tube + transformer) will give you an indication of the drive capability.

 

[mitsos]

I just fixed 2 of these... They have accutronics tanks in them, I might be able to measure DCR for you on Friday which you can match with an accutronics chart I found online.

EDIT: IIRC it had 4 springs, and the input DCR was very low, like 1-2 ohms, and I think it was a Type 4.

Here's the reverb driver schemo. Circuit is on the big PCB under the modules.

 

[pucho812]

awesome. thanks so much. this place rocks 8)

 

[DerEber]

I have an 1220 laving around in pieces: I remember the Reverb did never work. But still possible that there is the tank insinde. If you don´t find and good replacement in your country I can take a look if there is a tank inside. I´m in Germany. But very likely you finde something suitable in your area.

 

[mitsos]

I have an 1220 laving around in pieces: I remember the Reverb did never work. But still possible that there is the tank insinde. If you don´t find and good replacement in your country I can take a look if there is a tank inside. I´m in Germany. But very likely you finde something suitable in your area.

If you could check yours, I couldn't see any stamped numbers on it, just an Accutronics sticker. I found this stamped in ink, but it doesn't match any accutronics code:
27-04-041748-01

I'm pretty sure it's a type 4, and if I had to guess (DCR seems about what I remember from when I measured them), I'd say it's the fist one on this list:
http://roymal.tripod.com/accutron.htm

Didn't get to do a DCR test today though, but I might be back there this weekend.

hope that helps a bit.

 

[DerEber]

could not find a reverb tank inside 
Maybe thats why the Reverb was never working.

 

[mitsos]

Did you ever find a reverb tank? As luck would have it (yours, not mine )  I have a 1220 coming in for a visit, so I can measure the DCR off the coils if you still need it.

 

[mitsos]

hey, finally got to look at the 1220 reverb. DCR of the coils measures 2.3 Ohms input and 176 Ohms output.  I'd replace it with a type 4, input impedance 8Ohms, output 2250.  No idea what decay time but this one seems long as heck.