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Hoffman Amps Forum image Author Topic: Reverb Tank for Custom Kraft Model 880 (Supro s6622)  (Read 2379 times)

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Offline gtrbryan

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Reverb Tank for Custom Kraft Model 880 (Supro s6622)
« on: November 30, 2016, 09:54:51 am »
I have an old, 1960's Custom Kraft Model 880 amp.  This amp is Valco made (I think) and very similar to the more common Supro Corsicca s6622.  It has the cardboard reverb tank that doesn't do the greatest job.  I would like to try a new tank.  Any suggestions on values?  I came across the page on the internet where an accoutronics tank was used, but I have no idea if this is correct. http://www.smpartizan.com/?page_id=989 The  Supro schematic which I think is very close to the Custom Kraft except for an added tone control is at http://el34world.com/charts/Schematics/files/supro/supro_s6622.pdf. 

Is there any way to test primary/secondary impedance?  I would think I just need to get close.  Thanks for any assistance. 
« Last Edit: November 30, 2016, 10:02:58 am by sluckey »

Offline sluckey

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Re: Reverb Tank for Custom Kraft Model 880 (Supro s6622)
« Reply #1 on: November 30, 2016, 10:36:38 am »
Quote
I have no idea if this is correct
That tank will work in that Supro amp. Can't say about your amp yet.

Quote
Is there any way to test primary/secondary impedance?
Disconnect the tank. Measure the input resistance. Measure the output resistance. Compare to the table on page 4 of the attached pdf...

I would suggest you use a long tank (4xxxxxxx) rather than a short tank (8xxxxxxxx) if it will fit your cab.



A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline gtrbryan

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Re: Reverb Tank for Custom Kraft Model 880 (Supro s6622)
« Reply #2 on: November 30, 2016, 11:24:29 am »
When I measure, should I measure resistance from tip to ground on each side of reverb tank?   

Offline sluckey

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Re: Reverb Tank for Custom Kraft Model 880 (Supro s6622)
« Reply #3 on: November 30, 2016, 11:35:27 am »
There are two wires that come from the input transducer. Same with the output transducer. You want to measure resistance between these wires. If they connect to an RCA jack just measure from the tip to the shell of the jack. The shell may or may not be isolated from the chassis.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

 


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