From larrys–(at)–ol.com Sat Aug 31 09:46:42 CDT 1996
Article: 21827 of alt.guitar.amps
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From: larrys–(at)–ol.com (LarrySB)
Newsgroups: alt.guitar.amps
Subject: Re: Sovtek 5881 and 6L6 — Quality?
Date: 31 Aug 1996 02:35:54 -0400
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<<<<<
a true 6L6GC (e.g. Phillips) has a rated plate dissipation of 35w whereas
a 5881/6L6 (Sovtek or otherwise) has a rated plate dissipation of 23w -
Sovtek labels their 5881's as 6L6GC's - this is fraud to me. How much B+ a
tube can handle will not tell how good it sounds. Sovtek 5881's can handle
upwards of 700 volts but most 6L6 amps have B+ voltages that lie more
around the 365 to 420 volt range; so a high-B+ tube is irrelevant.
>>>>>>
Actually, according to my 1979 Sylvania tube data, the 6L6GC is rated at
30 watts max. I beleive the 7581 is rated for 35.
Though I am not fond of the Sovtek 5881WXT, I have to admit that it is a
very tough tube and it *does* in fact have good power dissipation. Other
people have bench tested the Sovtek 5881WXT to more than 45watts plate
dissipation before meltdown.
I don’t think New Sensor is misleading anyone on that one. I don’t have a
clue with what they are labeling as 6L6GC and 6L6GB. The sheet I’ve seen
says they are slightly off-spec 5881’s. What the heck that means is
anyone’s guess.
The Sovtek 5881 isn’t really a 5881 at all. It’s a Russian type 6pi33C.
The spec sheet I’ve seen was derated for *military* usage in avionics and
battle equipment. In fact, it’s supposed to be a servo amp/voltage
regulator for some models of Mig jets. It has very good shock ratings,
and a long specified life at derated voltages. The plates are quite
beefy, and the internal structures are heavily built. Much more heavily
built than NOS USA 6L6GC (I have a whole box of those to look at.)
Comparatively, the Sovtek plates are about 1/8 inch shorter than the late
production Phillips 6L6GC. The actual useful area looks identical.
I know many gigging/touring musicians who make a living with Sovtek tubes.
They are certainly a good tube for the money. Considering their low cost,
they do deliver a favorable cost/performance ratio.
My gripes with the tube is that it doesn’t sound as good as better 6L6GC,
and it doesn’t last as long. (probably due to cathode coating
differences). There are a lot of structural parameters that set the sonic
character of a tube. The motivations behind the russian tube seem to be
oriented in the favor of durability and cost savings. There is little
curvature in the Sovtek’s plate, where the NOS 6L6GC has a pronounced
curved area. The boxy plate probably eases construction and improves
structural rigidity. The curvy plate probably contributes to a cleaner
tone and wider response.
—
Dr. Nuketopia
Technology Director of the World-Wide Monetary Conspiracy
All opinions strictly reflect the party line.
Read the Blue Glow in Tubes FAQ at http://www.persci.com/~larrysb
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Lawrence Barras, copyright 1996. All Rights Reserved.
