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floobydust wrote:

Some very good points here... if I downloaded the correct schematic from your site for the 6-channel Melq amp (also has the term DSET in the title) then you have created a 6-channel SET amp with built-in crossover points. Your first comment makes sense but only for the SET stages that clip the low frequency response out. The full-range and low frequency SET sections are still succeptable to saturation and field collapse.

Yes, but the entire concept of DSET (or Dedicated SET) is disregard the min inductance always to have another channel as soon he saturation of OPT core might be an issue. I mean in DSET would the channel is designed for HF response only. The LF left over is handled by the LF DSET that is made by totally different rule of the SET game. BTW, to understand the Milq properly you might get the full-range Milq – it more illustrative wjat the amps is all about.

http://www.romythecat.com/PDF/Melquiades_SET.pdf

floobydust wrote:

Driving current is still a concern with any tube. You can use some basic formulas to calculate required slew rate versus bandwidth. Your input tube is biased around 4V per the schematic referenced above. My post was specific to the output tube being the 45 or 2A3. The same would apply, but of course the figure would be much lower due to the low voltage swing and whatever the total input capacitance of the stage is. Of course, this is fairly insignificant compared to the input cable capacitance. Looking at the 6C33 output tube, it's quite significant.... for sake of argument…

It is not for sake of argument. The 6C33 is VERY capacitive tube and it is now so simple to drive it. The DHT tubes from this respect are much mach easier and friendlier load.

floobydust wrote:

The 5814A is a ruggedized and improved version of the 12AU7. It has a beefier heater, tighter specs and generally a more robust mechanical structure, i.e., thicker mica supports and in many cases a 3rd top mica disc to enhance rigidity. Beyond this, you design with it like any 12AU7. A very good tube in general. Unfortunately I don't have Russian bottles in my collection... perhaps I should give the 6E5P a try... thanks for the recommendation.

There is a lot of data at this site about 6E5P. It is up to 40mA small 9 pin tube with gain of 30 and 4V on grid. Do you know any other driver that can with one stage to swing 120V at 30mA. It also has some interesting sonic qualities

http://www.romythecat.com/Forums/ShowPost.aspx?PostID=4805

There are tones of them on eBay for $2 each.

floobydust wrote:

On a side note, looking at the specs for the 6C33, I can't help but think that this tube might have had the western 6336 as a model.... maybe, maybe not. The 6336 is designed in a similar way and can actually replace up to 3 6080 paralleled tubes. Another beefy guy with two independant triode sections.

Nope, the 6C33 was one of the very few pure Russian designs, not stolen from West

http://www.romythecat.com/Forums/ShowPost.aspx?PostID=6140

floobydust wrote:

I think I'll agree less on this point... or perhaps we're defining things differently. My point is to limit low frequency to the output stage so you don't have issues of saturation or field collapse, not using it as part of a crossover turning point. In any case, using it a crossover turning point, it's only 6dB/octave and you'll probably want it steeper than that for your MF crossover.

Acalsy I do not know at this point how I will end up for my MF crossover. If I do for DHT and two stages then I would need to reevaluate where I would put the crossover. I might keep it as it is now or might be the coupling cap will work out for me this time. Another option is to put a between the 6E5P and DHT tube a fast inner-stage transformer with around 1H-2H inductance and very limited turns. If I kill all LF before the driver state (as I do now with me RL filter) then I have no capacitance signal path that might be a good way to go (let discard the caps in PS). The point is that with no inductance, very low power and with a fast core the fast inner-stage transformer might have negligible phase problems up to 100K-200K and it might be a good coupling solution.

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