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decoud wrote:

Romy, can you be persuaded to post a sketch of what you think the optimal 2 channel Melquiades circuit would look like?

Decoud, I do not think that there is such a thing as optimal DSET. The entire concept of DSET is a DEDICATED SET or the amps that dedicated to serve the specific purposes. If you look at the schematics of my 6-chennal Melquiades DSET then it gives a very good blueprint how the 2 channel Melquiades might be organized. Still it would be all depends what you would like to accomplish and what are the condition of your acoustic system/room.

Very generally, let make a mental exercises. In order to make a proper 2 channel DSET (doe sake of simplicity let look for identical output tubes) you need to have properly sounding full-range amp and confirm that it does what you feel it right. The amp must have enough power to driver your system.  Then you make two amps identical amps for LF and HF and define what you would like to have a crossover point between them. For the LF amp you’re built a large inductance out transformer and do not worry about the capacitance of that transformer. It will be large but cheap. Target your bass transformer to roll off at 2-3 octaves above your crossover point. For HF amp you make a high quality low capacitance transformer but do not worry about inductance and the necessity to care spare DC current. In fact that transformer should have absolutely minimum inductance, target 3-4 octaves under crossover point. The coupling capacitor of the HF amps acts as the high pass filters, preventing the low inductance HF OPT to be stressed by full-range signal.

So, not you have a perfect DSET configuration and you need to optimize your loading for each channel. You might (or might not) discover that you would like to drive bass with very different operation point then you would need to make charnel in LF’s amp power supplies.

Now, what you have two perfectly operating narrow range SETs you look at them and try to remove a common denominator from them. You might combine drivers, power supplies, servile elements, chassis, controls, filaments, bias… whatever you found is combinable. It might be that 90% of both DSETs would be combinable.  In some case you can have one SET with two out tubes and two output transformer, driven from the same driver stage… it all depends…

In some case you might chose less powerful tube for FH and more powerful tube for LF. In some cases you might have two-stage DSET for FH and but for LF to use a big transmission tube and to put some kind of cathode follower between the HF’s driver tube and the LF output tube, making the LF to see 3 active elements. That would be the same DSET idea…

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