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RE: Regulator Tubes ? - Hoax or just a cruel joke?

Posted by Bambi B (A) on July 7, 2009 at 13:14:55

In Reply to: RE: Regulator Tubes ? - Hoax or just a cruel joke? posted by HoosierAudio on July 7, 2009 at 12:19:02:

PAINTING: "Death of General Electric 6550A"


JohnC,

As I don't have a clue as to the way tube regulators work, it didn't occur to me that there would be interactions with the output tubes to consider also, but it makes sense. And, unless I'm reading you wrong, you're giving more emphasis to the regulator duties than possible sonic benefits. Am I correct then in assuming you would disagree with the poster here who mentioned that his experience was that the regulator had more impact on the sound than the output tubes?

I'd mention that I've now used Philips ECG 6550's for both the regulator and output tubes for more than 10 years and had not had problems on power up or down.

And, yes, it seemed to me the regulator must be very little stressed as I think the GE one lasted through 4 sets of GE 6550A's. Unfortunately, the arcing event depicted in the painting above was the end of the GE era for the D115 about 10 years ago. A pity as those were fantastic in the D115- more authority than the Philips and still very detailed and spatial. The Philips though do have a slightly more nimble feeling- perhaps in the way Telefunken ECC83 do- that odd airiness.

On that subject, could you say a word more about the sonic effects of the regulator? Can you say which were the several tried?

It's quite possible that the D115 and SP10 regulators are just fine- I think the D115 tube would have only 1,500 hours or so. The problem is supply and the cost in the future when I will need to replace them. As power tubes are used up more quickly than preamp tubes and the guitar crowd in the millions have discovered NOS output tubes, I see the NOS 6550's and 5881's going for far too much money- GEC's can be $175 each.

Someone gave me an ST70 and I saw GZ34 rectifiers were becoming amazingly expensive so I had the foresight to buy I think 3 or 4 NOS Mullards and a couple of Philips Miniwatt / Valvo - and hating then paying as much as $25 for a single tube. Now, if I intend to keep the SP10 and/or D115 I think I'd like to have a set for the dark days ahead.

Given your account, I'm not now so confident in the SED as regulator- though I imagine that's what ARC would send me for $75 or so. I hadn't heard of SED 6550 being unreliable in any ARC use before, but it's obviously a known problem. Perhaps ARC puts their supply through a long burn-in and on-off cycling at high currents. If the SED, one of the best 6550's made today, does not behave with itself as a regulator- a breakdown in self-regulation!, I think we may be seeing a future tinged with unecessary Entropy!

Yes, good to hear from a familiar name and fellow SP10 club member.

Say, what tubes are currently in your SP10?

Cheers,

Bambi B

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