I sold my tube amp and want to build an SET to go with my Klipsch La Scalas. I used to be an electronics tech and can build from a schematic, and have done so many times.
Not looking for a kit, just a schematic that works. I thought of the Decware Zen but the schematics I found on line just don't look right.
There are plenty of good SET designs out there, can anyone here recommend one?
Thanks
Not looking for a kit, just a schematic that works. I thought of the Decware Zen but the schematics I found on line just don't look right.
There are plenty of good SET designs out there, can anyone here recommend one?
Thanks
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with that kind of sensitivity you got a lotta options.
this one: my CELLINI triode amp
was supposed to be a ‘starter’ amp, my first tube amp. It used not so fancy parts, a bit of a tinkerer’s odd ball amp. But today, more than a decade later, it’s still my best tube amp.
You’ll get suggestions for way better amps, much more popular etc. but I thought I’d throw this one out because it is one of those under-estimated pleasant surprises. Not so long ago it went up against a SIT amp into a pair of MA Alpair 10.3’s and came out remarkably well.
this one: my CELLINI triode amp
was supposed to be a ‘starter’ amp, my first tube amp. It used not so fancy parts, a bit of a tinkerer’s odd ball amp. But today, more than a decade later, it’s still my best tube amp.
You’ll get suggestions for way better amps, much more popular etc. but I thought I’d throw this one out because it is one of those under-estimated pleasant surprises. Not so long ago it went up against a SIT amp into a pair of MA Alpair 10.3’s and came out remarkably well.
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Klipsch La Scala speakers are 105 dB. sensitive. The 2 WPC triode wired "12" W. multi-grid power tubes yield is plenty.
What might be an issue is damping factor. I'm thinking a linear (unbypassed cathode bias resistor) EF86 pentode voltage amplifier DC coupled to a ZVN0545A source follower (for isolation from O/P tube CMiller) cap. coupled to the "final". Add "plate to plate" short loop NFB, for increased damping factor. Definitely use good quality O/P "iron".
The EL84/6BQ5 and its relations make good triodes, but the 6V6 family makes even better triodes. For this power range, it has been said that #45 DHTs are needed to best trioded 6V6 family tubes.
What might be an issue is damping factor. I'm thinking a linear (unbypassed cathode bias resistor) EF86 pentode voltage amplifier DC coupled to a ZVN0545A source follower (for isolation from O/P tube CMiller) cap. coupled to the "final". Add "plate to plate" short loop NFB, for increased damping factor. Definitely use good quality O/P "iron".
The EL84/6BQ5 and its relations make good triodes, but the 6V6 family makes even better triodes. For this power range, it has been said that #45 DHTs are needed to best trioded 6V6 family tubes.
Mine are 1981, which are 104db. The newer ones are 105. Not that it matters..
Is this the current schematic to build in post #186? Any clearer prints?
https://www.diyaudio.com/forums/tubes-valves/167872-cellini-triode-amp-19.html#post2318223
I mocked up an AC coupled, cathode biased version of Michael Koster's Schadeode so that I could easily test different tubes by changing the cathode resistor and the screen grid zeners.
https://www.diyaudio.com/forums/tub...tial-feedback-se-amplifier-2.html#post2710121
The plate to grid feedback is 98% by my seat of the pants calculations.
I tried the Rev1 circuit with 6L6WXT+, 7581, Philips top cap 6BG6GA EH 6CA7, 6CB5A and 6P20S, 26LW6 and 4D32.
The lower PD tubes produced 1 watt with midband distortion at 0.15% or lower, 8 watts at 1% and 10+ watts at 3%.
The higher PD tubes all performed better than this. The 26LW6 produced 1 watt at 0.1% distortion and 14 watts at 3%. The 4D32 produced 1 watt at 0.08% and 15+ watts at 3%. I only operated these tubes at 80% and 75% PD respectively, because my bench supply only produces 550 volts and my transformers were rated for 80ma.
After these tests I ordered a handful of 6LW6 tubes and intend to build a stereo amp with them. I intend to use the Rev2 circuit for this amp.
Steve
https://www.diyaudio.com/forums/tub...tial-feedback-se-amplifier-2.html#post2710121
The plate to grid feedback is 98% by my seat of the pants calculations.
I tried the Rev1 circuit with 6L6WXT+, 7581, Philips top cap 6BG6GA EH 6CA7, 6CB5A and 6P20S, 26LW6 and 4D32.
The lower PD tubes produced 1 watt with midband distortion at 0.15% or lower, 8 watts at 1% and 10+ watts at 3%.
The higher PD tubes all performed better than this. The 26LW6 produced 1 watt at 0.1% distortion and 14 watts at 3%. The 4D32 produced 1 watt at 0.08% and 15+ watts at 3%. I only operated these tubes at 80% and 75% PD respectively, because my bench supply only produces 550 volts and my transformers were rated for 80ma.
After these tests I ordered a handful of 6LW6 tubes and intend to build a stereo amp with them. I intend to use the Rev2 circuit for this amp.
Steve
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I should add that I performed these tests with Bud Purvine and James 5k ohm transformers. I could get more power from the 4D32 using the the 3.5k tap but it was not needed. My speakers are 95+DB efficient.
I tried cheaper transformers and got less power and higher distortion.
I used triode wired 6V6s in a bi-amp system and really liked them. So, I tried a JJ 6V6 as well. I got 2.4 watts at clipping and higher distortion overall.
Except for the 4D32 all the other tubes were acquired for $20 or less so the 6V6 is not even an option for me.
Steve
I tried cheaper transformers and got less power and higher distortion.
I used triode wired 6V6s in a bi-amp system and really liked them. So, I tried a JJ 6V6 as well. I got 2.4 watts at clipping and higher distortion overall.
Except for the 4D32 all the other tubes were acquired for $20 or less so the 6V6 is not even an option for me.
Steve
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