Slo Mo,
I'd love to hear what that amp sounded like. Go ahead and build it and let us know.
The big problems I see with it though, is that the 813 has a mu of about 8 in triode, so you're going to need at least 9Vpeak of drive to the grid of the first tube to drive the second one to full power providing it's giving it's full gain, which it won't be. I'd either choke or CCS load or IT couple the driver tube to allow you to get some current through it, and still have a somewhat sensible power supply voltage. I've not tried the 813 at low voltage, but I suspect it could sound pretty ordinary at low voltage and low anode current, but that's something you'd have to determine by experiement. But you'll still need a grunty medium gain stage at the front, like a 6BX7 or a 12B4A running hot.
Otherwise, it's sort of Sakuma-ish.
I'd love to hear what that amp sounded like. Go ahead and build it and let us know.
The big problems I see with it though, is that the 813 has a mu of about 8 in triode, so you're going to need at least 9Vpeak of drive to the grid of the first tube to drive the second one to full power providing it's giving it's full gain, which it won't be. I'd either choke or CCS load or IT couple the driver tube to allow you to get some current through it, and still have a somewhat sensible power supply voltage. I've not tried the 813 at low voltage, but I suspect it could sound pretty ordinary at low voltage and low anode current, but that's something you'd have to determine by experiement. But you'll still need a grunty medium gain stage at the front, like a 6BX7 or a 12B4A running hot.
Otherwise, it's sort of Sakuma-ish.
I like high voltage valves!
Hi,
Bas Horneman's 813 page is well worth a perusal:
http://home.zonnet.nl/horneman/
Cheers,
Hi,
Bas Horneman's 813 page is well worth a perusal:
http://home.zonnet.nl/horneman/
Cheers,
Thanks for the comments , guys,
I was originally going to draw up the schem for my 10 - 813 SE
amp, when it occured to me that this would be a fun alternative.
This one is much simpler than my 10-813 SE amp, though.
Let's see, if we draw 55mA through the 1st 813 , it should get a
voltage gain of 6 and a bit , so the preamp would need to give
about 30V p-p, my 10Y-300b breadboard pre should do that.
Dont know how the 813 sound at these low voltages, though,
maybe an 845 would be better?
I was originally going to draw up the schem for my 10 - 813 SE
amp, when it occured to me that this would be a fun alternative.
This one is much simpler than my 10-813 SE amp, though.
Let's see, if we draw 55mA through the 1st 813 , it should get a
voltage gain of 6 and a bit , so the preamp would need to give
about 30V p-p, my 10Y-300b breadboard pre should do that.
Dont know how the 813 sound at these low voltages, though,
maybe an 845 would be better?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.