In Reply to: RE: Sound Practices Information..... posted by GSH on June 28, 2012 at 16:13:56:
I neglected to mention something very important in this kind of amp-- it's critical.
When you're running a High-Mu, low current device as a driver-- that item must have unlimited plate power available, and it must have very tight voltage regulation.
If you attach a constant-current device-- either to the plate or the cathode of the driver stage, the performance should degrade because of the added phase problems initiated by the Band-Aid thus applied.
If, instead, the sound improves, and the amp has more power with the C/C applied, then that is proof of a power supply problem on the driver's plate supply.
The supply should have very tight voltage regulation-- you can't do this with any regulating device-- it will fail to closely enough follow music's changes. Instead, you use resistors for shunt-regulation. Ideally, you can run up to 40 ma., to ground, and use only 8 tenths of a milliamp of that for the driver plate current-- maybe slightly more-- one milliamp with a single section of 12AX7A-- which is recommended because so many excellent varieties are available today.
Sorry I neglected to mention this. If you've had problems, look here.
---Dennis---
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Follow Ups
- RE: Sound Practices Information..... - tube wrangler 21:08:43 06/28/12 (0)