Effects of lower voltage

[jestaudio]

Hi folks
Just finishing up a express with a valve rec instead of diodes, I expected to drop some voltage but I seem to have dropped a load, i'm looking at playing with the dropping string to bring the preamp voltages up a touch, I have around 150 on v1a and v1b rather than the 210 rom the scheme with similar voltage drops across the other nodes, on the other hand it sounds good but breaks up a little earlier than expected.
Any advice appreciated.
Tube line up is 3 sovteks and 2 6l6, cathode biased, i'll put in some better tubes once I,ve finished the build

[romberg]

Different tube rectifiers drop different anode resistance and thus drop different amounts of voltage. You could try a different rectifier. What kind are you using now?

Mike

[jestaudio]

Different tube rectifiers drop different anode resistance and thus drop different amounts of voltage. You could try a different rectifier. What kind are you using now?

Mike

Gz34, its no real biggie, I'll probably adjust the string to get the preamp and PI voltages closer and see where it goes from there

[geetarpicker]

In my experience low plate voltages and cathode bypass will BOTH lower your headroom.

Years ago I built an AC30ish circuit on a gutted Marshall Super Lead Chassis. I started with a cathode bias setup, but I wasn't getting enough headroom for what I wanted. Then I changed it over to a fixed bias, and with everything else unchanged that alone helped quite a bit.

You might try putting the bias circuit back to the original KF design, along with getting some of your B+ up.

[jestaudio]

In my experience low plate voltages and cathode bypass will BOTH lower your headroom.

Years ago I built an AC30ish circuit on a gutted Marshall Super Lead Chassis. I started with a cathode bias setup, but I wasn't getting enough headroom for what I wanted. Then I changed it over to a fixed bias, and with everything else unchanged that alone helped quite a bit.

You might try putting the bias circuit back to the original KF design, along with getting some of your B+ up.

I,ve altered the dropping string a touch and got the voltages a little closer, I also dropped a lower gain mullard in v1 and immediately found the amp very playable, the Gz seems to be dropping quite a bit in comparison however the low mains voltage in my area is not helping at all.
Overall the amp is getting close to where I want it, I do prefer the feel of a cathode biased amp at higher volumes to fixed bias amps.
Ill keep playing around and may put a switchable diode rectifier in for comparision,

[Zippy]

Ill keep playing around and may put a switchable diode rectifier in for comparision,

If you have a spare tube base, it's easy enough to make a plug-in solid state rectifier. Might be just the ticket for your needs.

[jestaudio]

Ill keep playing around and may put a switchable diode rectifier in for comparision,

If you have a spare tube base, it's easy enough to make a plug-in solid state rectifier. Might be just the ticket for your needs.

Chucked a diode rectifier board at the amp and its made next to no difference , the GZ is only dropping around 10 v in comparison to diodes,
The trafo is a 300-260-0-260-300 from MM,
Beats me, every thing sounds good and its pretty loud so I guess nothing drastic is wrong, I currently have it set up with a 5ar4/diode rec option switchable and a hi/lo switch on the voltage secondary's .
I'll post some pics once I,ve tidied it up a touch

[Blackburn]

Ill keep playing around and may put a switchable diode rectifier in for comparision,

If you have a spare tube base, it's easy enough to make a plug-in solid state rectifier. Might be just the ticket for your needs.

Chucked a diode rectifier board at the amp and its made next to no difference , the GZ is only dropping around 10 v in comparison to diodes,
The trafo is a 300-260-0-260-300 from MM,
Beats me, every thing sounds good and its pretty loud so I guess nothing drastic is wrong, I currently have it set up with a 5ar4/diode rec option switchable and a hi/lo switch on the voltage secondary's .
I'll post some pics once I,ve tidied it up a touch

I used that same PT from MM for my AC30TB/Rocket. It's a nice one!