The Revelator (Another Nice Tube Phono Preamp)

[Salectric]

I recall it well. The demo was in the EMIA room at the Capital Audio Fest several years ago. Dave Slagle had a prototype of what is now the EMIA “LR Phono Corrector” preamp and was using it to play LPs through stacked pairs of modified Quad 57s.

Michael and I were early arrivals at the EMIA room and we had maybe 30-40 minutes with just the two of us and Dave Slagle in the room. After listening a while, Dave asked us if we would like to hear it with a LCR module instead of the LR we had been listening to. He fiddled around with some leads coming out of the preamp, adjusted the level of his AVC to get the same volume, and we listened again to the same record. After that he switched to an RC module and we listened to the same track for a third time.

I also recall that I liked the RC version best, at least on the brief listen, whereas Michael preferred the LR. The RC was brighter and more lively and the LR was warmer and perhaps more subtle. The LCR was in between.

 

[izzy wizzy]

Hi Stephen. I wish I knew how he did this too, but it was in the emia room one year at capital audio fest.

Not certain but I think my dad was present for that comparison too. @Salectric, do you recall any specifics about the demonstration?

If it was EMIA that did this, then that's all I need to know thanks. I thought you did it with this phono circuit and I couldn't see how that would be possible.

How did you arrive at the values in the EQ? And is it driven from the CCS "mu out" or from the anode of the valve?

 

[Michael V]

If it was EMIA that did this, then that's all I need to know thanks. I thought you did it with this phono circuit and I couldn't see how that would be possible.

How did you arrive at the values in the EQ? And is it driven from the CCS "mu out" or from the anode of the valve?

Right, the 420a isn't a candidate for an LR or LCR eq. I believe it was a russian variant of the d3a. Clearly Dave knows what he is doing, but as @Salectric noted, the RC was a solid choice. And the fact that the two of us had different preferences says a lot, too - its also simply a matter of taste to some extent.

On the 420a, I use the mu out and played with an online calculator to find common values for the caps. Funny story actually, at first I mistakenly wired it up with the output taken from the plate. This did not work! It was so rolled off on top that I even checked my horns to see if the wires came loose. Then it struck me what the issue was.

 

[Michael V]

Thanks for sharing.
Reminds me of the old saying "the acorn doesn't fall far from the tree".
It is really great that you share this audio passion with your dad, he must be a pretty cool mentor.
Nice build and good insight into your thoughts on design and function.

Thanks for your kind words. Not just mentorship, @Salectric is a focus group of one! Over the years I've brought dozens of projects to hear in his system, which of course sounds incredible, which sometimes validates what I think is working well, other times gives me a reality check when I need it. Sometimes a component sounds great to your ears in your system in your room - but doesn't travel well. When it sounds great in a completely different context and to someone whose ears you trust, you know you're on the right track.

 

[MrEd]

Thanks for your kind words. Not just mentorship, @Salectric is a focus group of one! Over the years I've brought dozens of projects to hear in his system, which of course sounds incredible, which sometimes validates what I think is working well, other times gives me a reality check when I need it. Sometimes a component sounds great to your ears in your system in your room - but doesn't travel well. When it sounds great in a completely different context and to someone whose ears you trust, you know you're on the right track.

Envy and respect for sure. 😎

 

[Salectric]

I appreciate your saying that Michael, but I think the record should be corrected. I may have helped get Michael started, but these days he’s the one who teaches me. Michael is more creative so he’s more likely to try something new whereas I tend to be more of a follower.

I will never forget the day Michael brought over his new speakers for me to hear—-Altec 414Z and 802 in 32A horns. That experience turned my audio life upside down. I went from a horn-hater to horn-lover in one weekend.

I could also mention my 46 SE amps which are a carbon copy of Michael’s design or my DAC which uses the same audio circuit and power supply that Michael developed for his DAC.

So the student became the teacher.

 

[Wntrmute2]

You guys need to get a room.....Oh, wait a minute! Yuck😬. Never mind!

 

[Wntrmute2]

Anyone build one of these?