bass response at tube mixer

[giorgiok]

Hello  I just finished one project a four channel tube mixer and I would like your thoughts and help.
I quote the schematic below.
The only conversion that has been made is that I've added another channel to the existing plan.The result is very good, no noise hum,i have good isolation between channels ,and the unity gain I wanted.. in a few words it works like a buffer.The only negative thing is that it lags at low frequencies! :-\
Unfortunately I do not have a program to measure exactly what  doing but in relation to other projects I have done there is a difference.
Is there something to improve the bass response  thank you very much.

 

[giorgiok]

The board

 

[abbey road d enfer]

The only negative thing is that it lags at low frequencies! :-\

I don't see anything in the schemo that really justifies that, maybe the electrolytic of unknown value across  the 68r cath res of the 1st tube, but that would be a very small effect.
Maybe the output capacitor of 1uF is too small for the load you are presenting to it.

Unfortunately I do not have a program to measure exactly what  doing but in relation to other projects I have done there is a difference.

There are several free electronic measurement softwares, I would recomment RMAA.

 

[giorgiok]

The cathode cap that i use is 470uf.The other cap across the 100k resistor is 0.47uf.
Is any other software working for mac ,i don t have a pc.I search the net and nothing found for mac.
Thank you.

 

[ruffrecords]

Is any other software working for mac ,i don t have a pc.I search the net and nothing found for mac.
Thank you.

I recommend Room EQ wizard (REW):

https://www.roomeqwizard.com/

Not originally designed for audio measurements but it does a very good job of it. Runs on all platforms too. Very good real time analyser that can be used to plot frequency response using the white noise source.

Cheers

Ian

 

[giorgiok]

Really thank you for your answers