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If tubes amplifiers measure poorly, why are they perceived as sounding better?

No need for that. Just built a tube amp that runs at 2300V plate voltage. 200 watt per channel directly heated triode SET sound has to be heard to be believed!
Looks cool (not in a thermal sense), but I'd rather not get into an intimate relationship with my electric company.
 
Looks cool (not in a thermal sense), but I'd rather not get into an intimate relationship with my electric company.
A 1600W space heater would be welcome here this week (11°F, getting down to about 7°F / -14°C by Thursday). I'm tempted to fire up the 300B amp sitting in the corner.

Re the 833 amp, I'm not sure how you can get 200W out of it. Class A SE has a max efficiency of 25%. Plate dissipation is about 350W, which means that running full tilt, the max output power would be about 85W or so.
 
A 1600W space heater would be welcome here this week (11°F, getting down to about 7°F / -14°C by Thursday). I'm tempted to fire up the 300B amp sitting in the corner.

Re the 833 amp, I'm not sure how you can get 200W out of it. Class A SE has a max efficiency of 25%. Plate dissipation is about 350W, which means that running full tilt, the max output power would be about 85W or so.
The magic of Class A2. It's pure Class A1 up to about 40W, then moves into Class A2 and draws up to 180-200mA grid current in addition to the 160mA idle plate to cathode current.

No worry about blocking distortion as the input tube is direct coupled to the 833C...no coupling cap.
 
People say it's the 2nd order harmonic distortion, but a competent push-pull amp will have inaudible distortion. Perhaps this is true for flea-watt single-ended amps, but those are going to require going down another rabbit hole of high-efficiency speakers.

IMO there are 2 factors:
  • The inconvenience and expense, as in the cartoon.
  • Load dependency, which adds some bass warmth with most speakers.
 
That is WAY above the tube's ratings. Hope you have spares. :D
Been running the same pair for 10 years now. No issues. Haven't even had to adjust the bias very much. Rock solid.
 
Been running the same pair for 10 years now. No issues. Haven't even had to adjust the bias very much. Rock solid.
I'm guessing you aren't running much into the grid current range. :D

I remember the sims you posted on diyAudio. Did you ever post experimental measurements? That would be interesting to see.
 
In reality, the amps spend almost all their time in A1 and move into A2 on transients. The extra power is very useful in that situation, but running full time in A2 would make me deaf!
 
I'm guessing you aren't running much into the grid current range. :D

I remember the sims you posted on diyAudio. Did you ever post experimental measurements? That would be interesting to see.
I did post sine and square wave measurements on the completed amps as part of the build thread. If anyone is interested, the entire thread is here:

 
I did post sine and square wave measurements on the completed amps as part of the build thread. If anyone is interested, the entire thread is here:

Can you link to the post? That thread is ENORMOUS. ;)
 
After some hunting through the thread, here are screenshots of a 2kHz square wave through the driver stage and on the outputs. Not bad considering the parasitics inherent in a 60lb output transformer!
 

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After some hunting through the thread, here are screenshots of a 2kHz square wave through the driver stage and on the outputs. Not bad considering the parasitics inherent in a 60lb output transformer!
What's the load? Voltage level?

Did you run anything like a THD vs power curve to verify what power you can actually get?

Thanks much, the work is beautiful, and I'm sure it's expensive as well!
 
What's the load? Voltage level?

Did you run anything like a THD vs power curve to verify what power you can actually get?

Thanks much, the work is beautiful, and I'm sure it's expensive as well!
4 ohm resistive load.
To be honest, as it was 10 years ago I don't remember all the details, but I remember the dummy load got hot!
That's the extent of the testing done, as I was eager to get the amps installed for listening after spending damn near a year planning and building them.
Maybe after I retire this year I can go back and do more measurements, but they sound so good, and they are so, so heavy to lug down to my basement lab...definitely a 2-man job.
 
If you're ever in Central New Jersey I'm always open to hosting a listening session. :)
Thanks much! I'll bring the beer.
 
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