Need Opinion: Comparative Sound of Pass Cap-Coupled (Zen) vs. Direct-Coupled Designs

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plasnu

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Joined 2011
6L6, it's an interesting article, but it is natural to me to think there should be some reasons other than THD to make caps sound different. I don't think it's only psychological why Mr. Pass uses bypassing film cap for electrolytic output coupling cap for SIT-X amps. Also I could clearly hear the difference between electrolytic vs film for my speaker crossover. Power supply caps? So far, not really, though.
 
6L6

6L6

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I'm certainly not saying there's no difference in a filter cap. Nor is Stuart in his article. As for properly-sized coupling caps however, the measurements don't really bear that out.

THAT SAID, because we do not listen in a state of blind or double-blind, the psychological effects of knowing that the bypass cap is there is not to be understated... But that's a discussion for a different day.
 
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plasnu

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Joined 2011
6L6 said:
I'm certainly not saying there's no difference in a filter cap. Nor is Stuart in his article. As for properly-sized coupling caps however, the measurements don't really bear that out.

THAT SAID, because we do not listen in a state of blind or double-blind, the psychological effects of knowing that the bypass cap is there is not to be understated... But that's a discussion for a different day.
Click to expand...

OK, Thank you. :)
 
6L6

6L6

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This thread isn't about discussing capacitors. It's about building a Pass amp.

Which one of these is the most Ferrari?

garage-dream-06.jpg


It's a wonderful question... because they all are.
 
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Diogenio

Member
Joined 2004
Dennis Hui said:
Since you mentioned wanting to move onto speaker projects, I suggest you
consider also it suitability to your potential future speaker needs when
selecting an amp project.

Papa gave some comments on a number of amps in an older post:

https://www.diyaudio.com/forums/pass-labs/253334-sound-various-pass-amps.html#post3864501
Click to expand...

Dennis Hui:

Thank you very much for that link. This is EXACTLY the type of information I was looking for. Unfortunately, Nelson does not characterize the sound of his Zen series vs. the other designs...which is exactly what I was hoping to discover.

I need to re-state my intentions a bit. I've been out of the hobby for 12+ years. In that time, technology has advanced tremendously (look at cell phones, computers, etc) and I was merely questioning if Nelson's later designs resulted in significant sonic quality improvements over that 12-year period.

I do not think that is an unreasonable question to ask.

While I'm NOT seeking absolutes - nor for somebody to "tell me which amp to build" I merely wanted to know if the Pass DIY state-of-the-art has advanced significantly from the Zen days. I'm also NOT "obsessed with capacitors," as I have built many tube amps, all with output trannys that distort far more than any cap ever could. I merely brought up the cap-coupled Zen vs. the later designs which are direct-coupled. Was there an underlying reason besides circuit topology for Nelson to switch to DC circuits...or not? Again...an entirely valid question.

There are dozens of different Pass DIY designs out there, and it is unreasonable for me now at 65 years old to build every one...I'd probably die before I reached the end! I'm looking for a reasonably short path to a quality system to build, enjoy and stop tinkering with - as I have lots of other non-audio things to accomplish - while my remaining time on Earth ticks away much too quickly.

I have the Zen 9 PCBs and parts, and will go ahead and build it, as it was the cat's meow in DIY back in 2006. Somebody mentioned I might like the single-ended Zen V9 sound, and I DO like single-ended triodes! The other design most recommended to me is the M2. Far more power than the Zen, and the transformer-coupled, zero feedback characteristics are no stranger to me from my tube amps. I will also buy that kit as my only "modern" Pass DIY project. The only complaint I've heard about that one is the hum and noise picked up by the interstage transformer. If Nelson doesn't mind it, I probably shouldn't mind either. I usually don't put my ear on top of the drivers when I'm listening... :rolleyes:

Thank you to everybody for their informative comments.
 
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