• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6V6 line preamp

The pics.
 

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Ex-Moderator R.I.P.
Joined 2005
Iam more than happy to talkabout it in the BA3 thread.

ok, lets stick to that ;)

Nelson appears to sum top andbottomportion of PP Fe. Dont know why, and if you did the same to F5, you woyld find they are back to being similar again, in this respect.

maybe because in BA-3 FE the signal is summed into one, like a preamp (F5 jfets are not)
 
ok, lets stick to that ;)



maybe because in BA-3 FE the signal is summed into one, like a preamp (F5 jfets are not)

Tinitus,
Go to the BA3 thread. Look up Generg. He specifically addresses the issue after building his. You are probably right and I am wrong. What you say makes sense. Shows my ignorance. I concede.

The same gain like Botte between x8 and x9... for the unbalanced version:D


Bas,
On my end, it is saying the video is private.
 
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Basman,

WRT the noise you're experiencing... could it be your smallish choke is hitting saturation? Cuz your first cap is only 2uF (from memory) the PS behaves like a choke-in filter. Loading thoose 150uF pulls lots of current...
Perhaps you can experiment with a resistor of equal resistance in parallel with the choke to see what happen at half the power? Or replace it altogether ;)
 
OK, but grid stoppers should ideally be neither magnetic nor reactive.
I'll try without ;)

Maybe it's not the linestage at all. Since I can't hear the noise with headphones or on my computer room system.

I've been used to playing directly from my DAC to power amp. (Volume control digitally via my Squeezebox Touch)

Perhaps the gain of the preamp is now making the DAC (6N6P output stage) white noise audible?
 
diyAudio Chief Moderator
Joined 2002
Paid Member
Maybe it's not the linestage at all. Since I can't hear the noise with headphones or on my computer room system.

I've been used to playing directly from my DAC to power amp. (Volume control digitally via my Squeezebox Touch)

Perhaps the gain of the preamp is now making the DAC (6N6P output stage) white noise audible?

Very likely. Not getting it on headphones is a strong hint it may be a push to source hiss. If you can FFT the chain rings you would see exactly. Are the big system's speakers highish sensitivity or horn even? Multiways with dedicated HF units?