After swapping my TSE (Sovetek 300b, Trancendar 20w OPT - TT-020-OT, several years on the clock) in and out of my system with another amp, I noticed that my trebble was severely lacking. I've always thought so, but the A/B comparison really highlighted the issue.
I checked the frequency response (QuantAsylum QA400) and it appeared mostly flat to 20khz, but in reality there is a large difference to other amps.
Looking for improvements, I found the following post by George:
"The grid stopper is normally used to prevent oscillation. It has a second function here. The grid stopper resistor determines the time constant under overload conditions since it is in series with the grid. It also forms a low pass filter pole with the tubes Miller capacitance so it affects the high frequency response of the amp. A big resistor (10K) will eliminate blocking distortion in most cases, but it will kill your treble response in triode mode. It works in pentode mode though."
at
http://www.diyaudio.com/forums/tubelab/177194-tubelab-se-coupling-capacitors.html
So, would playing with this resistor value (R33 and R34 on the schematic) be wise? If not, any other suggestions to increase the top end?
Thanks!
I checked the frequency response (QuantAsylum QA400) and it appeared mostly flat to 20khz, but in reality there is a large difference to other amps.
Looking for improvements, I found the following post by George:
"The grid stopper is normally used to prevent oscillation. It has a second function here. The grid stopper resistor determines the time constant under overload conditions since it is in series with the grid. It also forms a low pass filter pole with the tubes Miller capacitance so it affects the high frequency response of the amp. A big resistor (10K) will eliminate blocking distortion in most cases, but it will kill your treble response in triode mode. It works in pentode mode though."
at
http://www.diyaudio.com/forums/tubelab/177194-tubelab-se-coupling-capacitors.html
So, would playing with this resistor value (R33 and R34 on the schematic) be wise? If not, any other suggestions to increase the top end?
Thanks!
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