That is just 1dB difference. As the one before.
Now to see about experimental error and changes due to gear, go to 500mV at 0 attenuation so the DMM can catch it better, let it there, then go -40dB (be sure there is no center trim button on the attenuator out of cal position). And measure again.
Now to see about experimental error and changes due to gear, go to 500mV at 0 attenuation so the DMM can catch it better, let it there, then go -40dB (be sure there is no center trim button on the attenuator out of cal position). And measure again.
42dB max and 0.97dB difference. When you will have more tubes maybe you will strike a 0.5dB combination or better.
At the above combination you had hit the 43dB max and ~1dB difference.
At the above combination you had hit the 43dB max and ~1dB difference.
That is with 192mV at 0dB attenuation as signal from your Leader gen. After -40dB attenuation for Itch input signal, 255-275mV on Itch's output will mean 43dB max gain right on spec and 0.5dB max tolerance.
I refer to the combination where you hit 274 using 192 at 0 attn. If you used 502 with that valves combination it will still be the same dB.
Yes it's the same tube combination only changes 502mV in place of 192mV. I have more 1578 can I try the new tubes, wich position V4 elevated 1578?
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There are two tubes in each stage between channels. Each one common functions as upper half CCS with elevated heaters while the other as lower half for signal with grounded heaters. They form the Mu follower stages.
Don't know without real examination. If you had followed the PSU schematic you could not had it wired wrong for heaters.
Yes I know my fault sorry, I guess tubes are OK or gain measurements results not OK, what do you think?