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In the Forum: Analog Playback
In the Thread: The K&K SE hybrid phono stage: a report
Post Subject: The what's how's and why'sPosted by Paul S on: 6/18/2007
Romy, I am aware of your well-reasoned prejudice against audiophile/boutique parts, and I agree that they are by-and-large the first recourse and last refuge of Morons.

I thought I'd chronicled this phono stage stuff so far, but obviously not in your terms.

I have never really considered parafeed as any sort of panacia, for any gain stage.  Since the best low-level gain stage I have heard was op amps, you might think I'd go that way...

Yes, this hybrid parafeed idea is mostly about constant current and DC blocking (to help the tranny), but it's also about a reasonably simple gain path.  And since this gain circuit derives from [old] microphones, that's probably another reason to stay away from it.

But I listed my "reasons" for trying this thing early on.

I never said I bypassed a cap.  I said the unit came with a bypassed 4 uF Kimber cap that I got rid of right away, because it just sounded like crap.

I did say that the original sound was foggy and reticent, and I did say that the original 3.3 uF Mundorfs cleared things up a lot but were bass/ambiance shy.  I was not sure about the wide and quite shallow upper midrange dip until the Cardas caps "corrected" it.  And I'm such a slut that I will accept/enjoy the results even if I don't know "why", although I do tend to ponder these things through over time.

Yes, I know the mathematical formula for bass cut-off, and I usually try to get away with as little capacitance as I can, in keeping with my generally hair shirt approach.  In this case there was truncation and uneven bass with under 4.7 uF.  In fact bass was wildly uneven with 3.3 uF, the first Mundorfs I tried.  Adding  .82 uF/channel helped, obviously, and with the 4.7 uF, bass and ambiance retreval are now excellent, for my system, to the point where I just want to listen now.

It's not logical, I know, but I am also wondering now if some of my "power problems" came at least partly as a result of "the wrong capacitors", since those problems have disappeared coincidently with the addition of capacitance at that station.  Yes, I realize that it could be a coincidence.

Regarding the Electrocubes, can I actually buy one or two Bs or Ds directly from the source?  I have not found a retail source for the B or D, and no source at all that I can figure out how to order from, so it has been for me just another one of those arcane references, like the one-of-a-kind step-up you use, no use to me.

The phono parafeed caps should be [at least] 250V in my unit, so the 600V is overkill, for sure.  So ponder the Mundorfs, at 1,200V, not to mention that Mundorf's anti-inductance idea is putting two double-sized, mirror-wound caps in series!

Again, I am perhaps guilty of a sort of least approach to everything hi-fi, including and maybe especially in the case of capacitors, so this case is actually quite a departure for me.  And I am glad it turned out right despite obvious holes in the "technical argument" for the move.

Using reverse quasi-logic, right now I would have to say that something in the gain circuit of this phono stage makes this particular cap important, because of the audible results.

If it turns out I was wowed by something shiny, I will of course get back and report on that, too.  But don't count on it; I've been at this a while.

Meanwhile, I have no urge to change out the Electrocubes in the Lamms, since they have so far clearly and faithfully reproduced every other improvement to date.

Lastly, these Cardas caps absolutely do not need a bypass.  HF is just excellent, as is.

Best regards,
Paul S

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