Davoli - Jolly 3

[Bernardduur]

Hi all!

Does anyone know the Davoli Jolly 3 amp? I just got this one and it sounds marvellous! A transistor preamp combined with a tube poweramp with an ECC83 coupled with an ELL80.

My main problem with the amp is the volume and the amount of overdrive.
- The volume is pretty low. With my telecaster I get a nice volume out of it but then it stops. With the volume knob cranked I get no overdrive at all....... only a volume that is acceptable. But there is not more volume. With a clean booster in front of it I get the amount of volume I need from this little amp.
- When used with humbuckers the unit distorts a bit when I attack the guitar. One big strum and I notice some overdrive tones from it. The volume knob is not making any difference.

My best guess is that the issue is the preamp. The one transistor preamp is just overloading with the humbucker and has not enough gain to overcome the tonestack's cut in volume. So working with a clean booster works like a charm! Dunno if I change the circuit a bit or just leave it like this....... the tones are quite nice



Oh, and the 'original' schematic I found online. Not completely readable though.......

[tedmich]

Wow that's a neat old amp! The ELL80's are hard to come by nowadays I guess.

I'd be tempted to replace the preamp's front end with one based on an LND150, see
FET Preamp with LND150 Operates on Tube B+, part 1
and links therein, also AX84

others here might know how to just supe up the old BC238 (BC113?) to handle a modern humbuckers output.

[Justin Thomas]

It's a Micro-Music Man! Cool old amp; love these little nuggets!

Justin

[J M Fahey]

1) old amps (specially European ones) were meant to *amplify* , not to distort, period.
So your amp is working as intended.
2) you can build a modern preamp, fed 25/30V out of tube +B and sporting a dual Op Amp, if you use a low idle current dual Op Amp.

I often use TL062 in such tasks, it needs only 400uA per chip (1/2 to 1/3 of what a single 12AX7 triode uses) and you can do anything which is done with Op Amps, including preamps, distortion, tone controls, you name it.
replace power supply R2 with 220 or 180k , put a 12 to 30V zener across C3 , in fact I'd replace C3 with 100uF x 25v to 50V , depending on Zener chosen, and you can build almost any simple preamp (look at 10/15W guitar amps, including killer Marshall Lead 12) to drive the Tube section.

You have a single supply, so you must convert original circuits ... although Peavey Rage and others have single supply ones which fit right here ... just replacing TL072 with TL062 .