Jah Tubbys modified TUBE preamp
Posted: Sat Sep 27, 2008 8:23 pm
I'm proud to present what I think is the first tube modified and best Jah Tubbys preamp.
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.Big%20smile
I will post some more picture later from the sound system in use.
Any feedback welcome
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.Big%20smile
I will post some more picture later from the sound system in use.
Any feedback welcome