V1 split cathode
Moderators: pompeiisneaks, Colossal
V1 split cathode
Whats the benefits of a split cathode in V1 on a bassman micro variant?
Re: V1 split cathode
Less interaction between channels and ability to bias each preamp differently and/or use different cathode bypass caps. If you do this, remember to double the cathode resistor value if you want everything to remain the same. Shared 820R = single 1640R, 1k5 being closest standard value.
Re: V1 split cathode
Can't get my head around this V1 seems like and odd solution. Pin 1 100k 0,022uf, pin 2 68k, pin 3 820 ohm 22uf.
You do not have the required permissions to view the files attached to this post.
- johnnyreece
- Posts: 999
- Joined: Thu Jan 26, 2012 2:05 am
- Location: New Castle, IN
Re: V1 split cathode
Sounds like pretty standard values. Pin 1, plate resistor and coupling cap; pin 2, grid resistor; pin 3, cathode bypass cap and resistor (although, since it's only 1/2 of the tube, I'd double the resistor to 1.5k-ish, as was mentioned earlier). The other triode is unused in this configuration.
Re: V1 split cathode
The builder said (not me) it was a split cathode V1 but as was pointed out it only use one side. Just needed the confirmation.
Re: V1 split cathode
The builder either didn't understand how it worked or purposely chose to bias that stage hotter. If there is only one channel, it's not necessary to use the other half of the tube.
- johnnyreece
- Posts: 999
- Joined: Thu Jan 26, 2012 2:05 am
- Location: New Castle, IN
Re: V1 split cathode
In the typical bassman micro, V1 is paralleled. Wouldn't be hard to implement that here. Just 3 little wires...
Re: V1 split cathode
Your right there's only 1 channel but why do you add this extra lead from pin 3? Ground wire? The lead to the left is from pin 3, resistor is 2,7K.The other picture is the old board from above. Still learning but making progress.
You do not have the required permissions to view the files attached to this post.
Re: V1 split cathode
Looks like the cathode bypass cap is backwards, is there a picture of the complete build or are you still building it? Pin 3 is the cathode, if there's an extra lead maybe it is a shared cathode on another stage. Do you have a schematic/layout?
Re: V1 split cathode
The bypass cathode is correct because the leads are reversed. No I don't have any documents or schematic that's whats make it so hard to for me. I will continue to try and figure out the circuit. I know its based on a bassman with some tweaks. Fixed NFB, balanced bias, single channel, bass, middle, treble tonestack, bright switch, dual 6l6 output, diode rectifier.
Re: V1 split cathode
I don't see any extra wires on your tube socket picture. Do you have photos of the completed amp or is it still in pieces? You should make a layout and/or ask whoever built it for details. If it's push pull 6L6 it's not micro. Take a 5F6A schematic/layout and annotate the differences.
Re: V1 split cathode
Rather than just isolted photos of just the board or V1 socket, it may be helpful to provide photos that add up to provide a complete picture of what you're got there.
Whatever, as only half of (what I assume is) the V1 socket has ever been wired up, it seems that it's a single channel amp, probably with only 1 or 2 input sockets.
As such, the split cathode thing for V1 doesn't apply, as only 1 of its triode cathodes is being used.
Whatever, as only half of (what I assume is) the V1 socket has ever been wired up, it seems that it's a single channel amp, probably with only 1 or 2 input sockets.
As such, the split cathode thing for V1 doesn't apply, as only 1 of its triode cathodes is being used.
My band:- http://www.youtube.com/user/RedwingBand
Re: V1 split cathode
The problem is that the amp is in pieces at the moment and its not possible to get in touch with the builder, I've tried. These fotos are from the original layout hope it helps. Any pointers you guys can give me is much appreciated.
You do not have the required permissions to view the files attached to this post.
Re: V1 split cathode
Looks like the last guy mirrored an existing layout, might make more sense flipped upside down. Maybe it never worked properly and that's why it's in pieces?