Davoli Krundaal - Amplificatore D531T [schematic]

[modman]

It's cute and pink and it's probably a accordion amp, but got kind of intrigued by the tube setup:
1 x 12AX7 or ECC83
2 x ECL82 - which is a triode and pentode in one package!
3 tubes: 2 gain stages, tremolo, phase inverter and 10W output

106992510_10159483429099796_4840052784939772316_o-2.jpg (47.04 KiB) Viewed 3222 times

[modman]

I wasn't going to ... but I did. Paid too much, but what do you expect trying to wrestle a pink amp from a very nice lady...
it's very sensitive to high output humbuckers
the tremolo doesn't work.



Just a demo, no work done yet...

[modman]

In the first stage, I wanted to get it working again and not do any mods, just get the tremolo tremming again. This amp has been worked on before. One of the two can capacitors has been replaced and much of the power section was redone... This surprised me because there the chassis screws were still sealed with yellow paint.

The schematic contains an error: the first dropping resistor is 5k/4W, not 47k.
One of the 330k to ground before the output tube on the verge of breaking, and this pulled off the bias completely so basically running in class A, on one power tube.
Ressurection of the tremelo was just a matter of replacing all the tremolo capacitors. Nice Ducatis but they were all completely out of whack, the 100nF measured 550nF, the 47nFs about 80-100nF...
The Danish Peerless speaker seems to have been a replacement, and the baffle cutout is a bit too wide, so it is only attached by 2 screws for now. I may have to make a new one.

I would like to restore the amp the way it originally was, at least layoutwise, but I have not found any gutshots of this unit online. The circuit is very close to the Hagstrom 39, the only difference is the way the tremolo is connected and that is has a EZ81 rectifier while the Davoli has solid state rectification. Then again the Hagstrom was built on pcb, the Davoli seems to have been point-to-point.

[soulsonic]