Jah Tubbys modified TUBE preamp

I'm proud to present what I think is the first tube modified and best Jah Tubbys  preamp.

See the picture in the link below :

http://www.box.net/shared/qixbs545cg

I'v also upgraded the opamps and nearly all capacitors to premium audio caps.
The opamps where simple and low cost TL072 and now are high quality opa2134.
The caps that Jah Tubbys did build in where absolutely not audio caps - industrial ones - and there was even those ugly sounding ceramic caps all over the audio path.
I did upgrade them with quality MKP,Teflon,Styroflex and 3 big paper in oil Obbligato caps.
I did a backward engeneering to get schematic and mesured all caps values - because the values were scratched off the caps by Tubbys- and then I simulated the preamp in PSPICE.
These simulation confirmed what I did hear before from different Tubbys 3 way preamp. The crossover point are very "exotic" and the values for graphic equalizer awfull.
Now the crossover is more narrow than before resulting in better low mids definition.
The value for the equalizer are now very sharp resulting in better control over the different bands.
The tubes are 6H6P with high power output capabilities to drive plenty of amps.
The tubes are on the output in an SRPP configuration.
Oh and I did ad stereo input for the two deck so now you can play those old stereo records like Twinkle Brothers Natty Dread Uptown where the voice was on the left chanel and the music on the right one. Now you can hear both!!!
I've made this upgrade for LION YOUTH SOUND SYSTEM from Geneva,Switzerland and now the sound is really awesome and they are really happy.

I will post some more picture later from the sound system in use.

Any feedback welcome

massive amount of work on that..

wouldn't it be better/easier though to just build a newly designed one from scratch?

wicked!

Is valve modifying gear something you do lots of? Would love to see more of this kind of work.
S

I don't have a valve pre amp but I've been thinking about having one made for some time. I've also considered just putting in a TLA valve stage so that it gives my Hi-Fi a valve character.
It's easy - especially for reggae sound ites to romanticise on tube amps like I do; lugging them around and maintaining them would be a different matter. Still, when I built up my Hi-Fi I wanted to recreate a certain nostalgic sound so used vintage amps including that power amp DB, it's a hand built 300W 8 x 6L6 monobloc. At the moment I use it to drive a single sub between 30-80 Hz and together, for the power, they sounds like nothing I've heard!



That's the insides. Even the transformers are hand wound!

S

Really nice stuff!

I have a thing for valves - I try to stick them somewhere in the signal chain when I can't use a valve amps. You can find all sorts of schematics (or design your own) for valve things on the net (instead of buying from TLA...). I think there's a few on my hard drive if you're interested...

Hand wound trannies - there's some soul in that amp!

PS

Have you heard some of Nelson Pass's solid state amps?

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Topic: Jah Tubbys modified TUBE preamp Posted: Today at 12:06am By sKs01

what was the overall cost of the project if you don't mind me asking?

I did the hole work for nearly 900.- Swiss francs.

Edited by Joseph Redhemption - 19 October 2008 at 11:04am