Hi, I'm building this line preamp to srpp + output buffer.
I have, for the heaters, a toroidal with two 6A 0-8V secondaries.
The tubes I use are 6n23p (instead of ecc88).
The B + is 180v.
For the SRPP stage I would like to use 4x 6n23p tubes, instead of two.
Of each valve I have two options.
First option:
Use only one triode and leave the other unused (if not used they advised me to put the grid on gnd).
Second option:
Put the two triodes of each tube in parallel ... just so as not to leave the second triode disconnected.
Which solution is the best?
The purpose of using 4 separate tubes is to be able to lift the heaters of the high triodes separately from the low ones and, at the same time, not to pass the "left and right" signal in the same tube (even if it has the screen).
With triodes in parallel I would have half the output impedance.
I don't care, I have a 15mA polarized CF for the output.
Thanks!
I have, for the heaters, a toroidal with two 6A 0-8V secondaries.
The tubes I use are 6n23p (instead of ecc88).
The B + is 180v.
For the SRPP stage I would like to use 4x 6n23p tubes, instead of two.
Of each valve I have two options.
First option:
Use only one triode and leave the other unused (if not used they advised me to put the grid on gnd).
Second option:
Put the two triodes of each tube in parallel ... just so as not to leave the second triode disconnected.
Which solution is the best?
The purpose of using 4 separate tubes is to be able to lift the heaters of the high triodes separately from the low ones and, at the same time, not to pass the "left and right" signal in the same tube (even if it has the screen).
With triodes in parallel I would have half the output impedance.
I don't care, I have a 15mA polarized CF for the output.
Thanks!
Hello, I am big fan of the SRPP, actually I built a phono/line preamplifier with 6N23P and E88CC throughout, see
Phono preamplifier acceptable S/N ratio
My advices coming from much experimenting are the following:
- Increase the B+ to 250...300VDC
- Get the signal from the top cathode
- No need to use a cathode follower after the SRPP, since it has low output impedance (about 1.2 to 1.5 kohms)
- No need to elevate the heater in my experience, just tie one end to GND
- Connecting tubes parallel is not a good idea, not necessary IMHO
- I biased the tubes for 5mA with Rk=1.5k
- I used both halves of the double triode as the lower and upper part of the same SRPP stage. L channel one tube, R channel another tube.
Phono preamplifier acceptable S/N ratio
My advices coming from much experimenting are the following:
- Increase the B+ to 250...300VDC
- Get the signal from the top cathode
- No need to use a cathode follower after the SRPP, since it has low output impedance (about 1.2 to 1.5 kohms)
- No need to elevate the heater in my experience, just tie one end to GND
- Connecting tubes parallel is not a good idea, not necessary IMHO
- I biased the tubes for 5mA with Rk=1.5k
- I used both halves of the double triode as the lower and upper part of the same SRPP stage. L channel one tube, R channel another tube.