What's the output impedance since you placed the output cap at the plate instead of the cathode of the top tube?
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Hello, I would estimate output the output impedance from the anode is probably around 2k to 2k5.
With the output impedance in mind I did wire a second set of output sockets with mu output from the upper valve cathode of the last stage. I do perhaps marginaly prefer the non mu output, but there's not much in it.
fdegrove, on first listen I under estimated the rp of the 6C45, so my riaa was a little out, once corrected, and now burnt in a little its starting to sound quite good.
I think changes would be regarding method of construction, rarher than actual schematic. As is, Its a good test bed and despite the long component lead length, this dosent seem to have effected the noise or stability, but I would build it In a more compact manner if I were to rebuild.
Also it does get quite hot, so maybe reduce the raw heater voltage a little or add an RC filter to the heater supply's.
I did also consider the possibility of a variable negative bias supply for the last two stages and connecting their cathodes direct to ground, I may try this as I have one spare wire in the outboard PS umbilical.
Cheers
With the output impedance in mind I did wire a second set of output sockets with mu output from the upper valve cathode of the last stage. I do perhaps marginaly prefer the non mu output, but there's not much in it.
fdegrove, on first listen I under estimated the rp of the 6C45, so my riaa was a little out, once corrected, and now burnt in a little its starting to sound quite good.
I think changes would be regarding method of construction, rarher than actual schematic. As is, Its a good test bed and despite the long component lead length, this dosent seem to have effected the noise or stability, but I would build it In a more compact manner if I were to rebuild.
Also it does get quite hot, so maybe reduce the raw heater voltage a little or add an RC filter to the heater supply's.
I did also consider the possibility of a variable negative bias supply for the last two stages and connecting their cathodes direct to ground, I may try this as I have one spare wire in the outboard PS umbilical.
Cheers
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Hi,
@velvetsunrise : Just let me know what you want to do and I'll chime in if you'd want to.
Running the eaters at 6VDC iso 6.3 would help increase valve life . Replacing OD3 and OC3 by their seven pin alter ego would leave a lot more real estate as well.
As said whenever you're ready.
Cheers,
@velvetsunrise : Just let me know what you want to do and I'll chime in if you'd want to.
Running the eaters at 6VDC iso 6.3 would help increase valve life . Replacing OD3 and OC3 by their seven pin alter ego would leave a lot more real estate as well.
As said whenever you're ready.
Cheers,
Here´s a tube to try out. Russian single pencil triode. µ is 100, and noise is extremely low:
http://www.russiantubes.ru/prop.php?t=12&p=322
https://frank.pocnet.net/sheets/113/6/6S32B.pdf
http://www.russiantubes.ru/prop.php?t=12&p=322
https://frank.pocnet.net/sheets/113/6/6S32B.pdf