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Help with these Russian GU50 tube amplifier

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R

revintage

Member
Joined 2007
Albertli,
This is a simplified model where your PSU and OPT will work(400V/3,5kohm). Will clip at ca 30V ptp into 8ohm. 6E5P at 200V/12-15mA.
 

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mogliaa

mogliaa

Member
Joined 2009
bartola.co.uk/valves/
Not sure if of any use here, but was playing today with my curve tracer and did a plot for the GU-50 in triode mode. Unfortunately my anode supply can only swing to 300V at the moment, so curves are limited to that maximum anode voltage.
I took measures from the plot indicating that gm=4.4mA/V, u=4.5 and ra=960. Does it sound about right? :rolleyes:
You can download the curves from here:

My Photos


Cheers,
Ale
 

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M

matejsirk

Member
Joined 2008
marsaudio.eu
My PSE prototype

This is my PSE prototype - almost finished. B+ 410V, driver ECC801S in SRPP, negative bias (GU50 - around 45mA each), OT 3.5K:8Ohm. Interstage caps: Jantzen Audio Superior 0,22uF. Frequency response from 8Hz - 35Khz 0dB. GU50 in pentode mode - sec grid around 255V. Power >20W/8Ohm.
 

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Wavebourn

Wavebourn

Member
Joined 2006
wavebourn.com
mogliaa said:
Not sure if of any use here, but was playing today with my curve tracer and did a plot for the GU-50 in triode mode. Unfortunately my anode supply can only swing to 300V at the moment, so curves are limited to that maximum anode voltage.
I took measures from the plot indicating that gm=4.4mA/V, u=4.5 and ra=960. Does it sound about right? :rolleyes:
You can download the curves from here:

My Photos
Click to expand...

Hi Ale;

it would be nice if you show the curves up to +10 Volt on G1. 2 more lines on the picture! :)
 
Q

quikie22

Member
Joined 2009
Revintage's circuit will work very well.... my circuit is very similar, but my 6E5P run with a simple resistive plate load only. You could run the load as in Revintage's circuit, or with a resistive load or replace the load with a 60-80 Henry choke for the 6E5P.... each will have it's own special sound quality.... try it and pick the one u like the most.
 
R

revintage

Member
Joined 2007
Hi,
A choke is a very good idea. Would go for that if it was doable. Unfortunately it will be hard to tame the resonance peak in the low end. Resistive load is doable and sounds good but you can expect a significant rise in distortion compared to gyrator.
 
Last edited:
albertli

albertli

Member
Joined 2004
quikie22 said:
Revintage's circuit will work very well.... my circuit is very similar, but my 6E5P run with a simple resistive plate load only. You could run the load as in Revintage's circuit, or with a resistive load or replace the load with a 60-80 Henry choke for the 6E5P.... each will have it's own special sound quality.... try it and pick the one u like the most.
Click to expand...

Thanks and would love to try all those you recommend. I thought I'd start doing it as of Lars design. I'm making the wood chassis and would cut the aluminum top plate sometime next week.

Albert
 
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