If you don't need the gain since you make do with a dcb1, choose #144 which is a follower that Scott Gregory makes. The gain circuit you posted is right too, but we use an active regulator for B+ since then for both common cathode or cathode follower. Either Maida, or SSHV shunt reg (smoother).
Gives 15dB gain with the resistor, if its enough to your speakers. Just a little more with CCS load for the additional work and devices. No real boost. Would need careful suspension and placement to avoid microphonics when in gain mode. Use straight profile 6V6 bottle. Look for SSHV2. I would make double mono regs set at 45mA each.
yes, this and many versions over the years, AM864 was one of the first vari-mu as this one is modeled off of. Manley vari-mu is simular. The La-2a was based off of this design. The detection circuit was modified to drive the tb4 module instead of backing off the bias of the first stage.
90% of my circuits I build go into the music world
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Buzzforb,
You will not go wrong building this with AC as the heater supply. Later you can modify it to go DC if you find necessary. I doubt you will have any issue.
Shunt regulators need quite a bit of heat sinking for filament applications. If you feel DC is critical then use a CCS for to regulate the filament current.
For this pre amp spend your effort on the circuit and making sure that the tube is mechanically suspended to minimize vibration. You will reap many rewards doing that first.
You will not go wrong building this with AC as the heater supply. Later you can modify it to go DC if you find necessary. I doubt you will have any issue.
Shunt regulators need quite a bit of heat sinking for filament applications. If you feel DC is critical then use a CCS for to regulate the filament current.
For this pre amp spend your effort on the circuit and making sure that the tube is mechanically suspended to minimize vibration. You will reap many rewards doing that first.
Thanks SGregory, I was just looking at Rod Coleman heater supply. There is a guy on amazon offering matched quads of JJ 6v6 tubes. Do you think this is safe as I have a credit I would like to use it. Tube depot is the only other source I have found. Why the carbon film resistors vs metal film?
