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In the Forum: Melquiades Amplifier
In the Thread: Valve Preamplifier for Macondo/DSET
Post Subject: The known good solutionPosted by anthony on: 6/30/2022
 N-set wrote: |
Hi Anthony,
trying to copy a known good solution - too little time for experiments recently.
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Well, Romy had great results with the Placette and his Dannoys, so that is the known good solution as far as I am concerned. Sounds like the 10y will introduce far too much gain which you will have to attenuate thus likely ruining the sound. I mentioned system gain structure earlier, and it is very important, more important than the amplification stages themselves.
The 10y is a bitch of a tube. You cannot wind a good output transformer for it...anyone that tells you they can either are deaf or have very low expectations of sound...so for a preamp we are limited to different output topologies including the mu follower which Ale uses. Trouble with the hybrid mu-follower is that unlike an OPT we end up with all the gain of the tube which in my situation is excellent but in yours not so much. Ale does recommend a resistor divider to attenutate some of the gain and perhaps that is an option should you still go with the 10, but it is still attenuation, and resistor attenuation at that which may or may not be better sounding than letting the Slagle Autoformers do all the attenuating work (I have the silver version with the Bent AVC-1 which Dave made for me and John Chapman supplied the control circuitry).
There is talk that thoriated tungsten filaments (as used in most of the 10's along with several other tubes) are where the good sound comes from. I don't know if this is true but all DHT's are very sensitive to the quality of the heater power supply. You are likely limited to using the Coleman regs, which are very good, but I have used a CCS developed locally that is no longer available, and last time anybody checked is better sounding than the previous generation Coleman regs, although the latest version seems to be well regarded but I not heard them. I don't know how much of my sound is due the the over-the-top filament supply, but I reckon a good portion of it.
In terms of me going cool on my preamp, no, that is not true, I've just had trouble putting it in a box. Plus I need to experiment a bit because my one (new) high output source overloads the input of the preamp and I need to bias it deeper. It is still the best sound in my system, but that is my system, and I am not sure it will be the best fit for your system. Rerurn to Romy the Cat's Site