[larsthestrat]

okay, that's a good idea. I will check that one out. Do you mean bij Ra1 the resistor that was essentially 1M (pull down resistor)?
regards, lars

[mc_guitar]

Hello,

No Ra1 means the AnodeLoadresistor of the V1A system. Change it from 100kOhms to 68kOhms, which will get less gain out of V1A. Check the schematic Dirk has in the ValveJunior Mod section.

Cheers Michael

[larsthestrat]

hi,

thanks! so I need to change both R3 and R4, or just one of them?
grt. lars

[mc_guitar]

I would start by changing R3, then listen to the amp and decide whether it is clean enough.
Maybe clip C4 off, or as Dirk suggested make C4 switchable.

Cheers Micha

[larsthestrat]

I will do that and let you know!

[larsthestrat]

final quistion, I thought that bij removing C4 the amp losses some of it's bass. Is this correct?

[mc_guitar]

final quistion, I thought that bij removing C4 the amp losses some of it's bass. Is this correct?

No. C4 reduces the local negative feedback for that tubestage. With 22µ it should be almost fully compensated and you have no lnfb for the full frequnecy range. So you get more gain overall. If you only lower the value of C4, say 100nF you will reduce the nfb for only the higher frequencies. That will result in a higher gain for highs and a lower gain for the lows. So you will hear less bass, because it has less gain than the highs.
For that read http://www.freewebs.com/valvewizard1/gainstage.html

Cheers Micha