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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: I've not given up...Posted by anthony on: 8/22/2019
...on the Placette. Biggest problem at the moment is that it does not have any gain and I definitely need some gain.
What I have done is breadboarded a nice diy SS pre with 2x or 3x gain, dc coupled, current mirror, 100mA. It was started a couple of years ago and set aside. The output impedance has long been forgotten, but I can measure it.
A local guy, Clay Gieseler, makes some really well engineered SS amps, dacs, and preamps and I picked up a used pre of his design. It sounds really good, I like it. Perhaps that is just the extra volume, but nonetheless I like it. Change a couple of resistors to increase the gain a little more and it may be a keeper apart from the fact that it has only three inputs...Clay might be able to be convinced to make me a new one with more inputs. The VC is based on the Muses chip and sounds very promising.
Winging it's way to me shortly is a low noise, low thd, small, well engineered Gain Block One which is a simple SS gain stage made by Tasmanian Anthony Holton who is best known for his diy products and commercial SS amplifiers. It is DC coupled also and may be combined with a VC and input selector to make a preamp or perhaps used as a gain stage in the Placette thus making use of its excellent VC. This is more or less what Guy Hammel would supply and what you are using. Just whether or not it is best solution for me will be seen, it may best be used on its own.
On top of this, I have ordered parts to experiment with building some single stage DHT preamps. These can be prototyped quickly without wasting too much time. There are certain metrics that the preamp has to meet regarding low distortion, output impedance, current, noise etc. and if they don't meet them on the prototype then I won't put them in a case and keep them. I've been warned that the approach I am taking in the design may make them sound solid state, but that is really what I (think I) need, and there are really only a few ways these amps can be designed such that they will meet all the metrics while maintaining enough gain.
The whole process will be interesting, and I will learn a heap. Right now I wouldn't be game to guess which solution I will end up using, if any of these.Rerurn to Romy the Cat's Site