[DOUBT] Decibels and tubes.

[QSQCaito]

Well, i've just finished my TS. Still needs the DPDT + housing, so I can't tell if it works. Anyway, I'm planning my next build. It involves tubes, it's certainly a JCM 800 preamp copy.(If this can't be done/posted, let me know please) while reading about tubes at geofex first, I came up with this:

I know that the JCM800 preamp may not be the ultimate blues distorsion, but anyways.

FROM GEOFEX.COM -- This was not written bye me
How do I get...
Blues distortion? Made by overdriving preamp and power tubes a little, enough to just start compressing the peaks of the waveforms, and not very much high frequency content, by electronically cutting highs or running the signal into a speaker cab that acoustically cuts highs.
Guitar Player magazine ran a construction article on this very topic, modifying a Fender Bassman to be the "Ultimate Blues Machine". The article ran in 1995, authored by John McIntyre.

A recently voiced although intuitively applied idea in distortion is that tube distortion sounds best when each successive distortion stage is overdriven by less than about 12db. This has the effect of keeping the tubes inside the area where the signal is more compression-distorted than clipped. That is what those resistive divider chains between distortion stages are for inside those distortion preamp schematics. Mesa's distortion preamps are another good example.

Overdriving a tube stage too much gives you harsher clipping, not the singing, sweet distortion we want. To really get sweet, crunchy distortion, keep each stage that goes into distortion no more than 6-9db into distortion.

This can be found at http://www.geofex.com


We know that the JCM800 is a two 12ax7(or family) preamp. Those db I want tto reach (6-9), how can I achieve them.. is just hearing, component values.. different tubes, like 12au7?? If you need the schematic just let me know and It will get posted.


This thing really got me thinking, and it would be cool if I could achieve what posted before.

BTW, are "wall warts" that bad for tubes?? This project requires 220-12 12-220 ( the same, lol)


Thanks a lot, any help is indeed welcomed.


Bye bye

DAC

[QSQCaito]

BUMP IT :p


No clues ?


Bye bye

thanks

DAC