From gkaufma–(at)–u.edu Tue Jan 20 23:06:38 CST 1998
Article: 51766 of rec.audio.tubes
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From: gkaufma–(at)–u.edu (Gary Kaufman)
Newsgroups: rec.audio.tubes
Subject: Re: 5V4G vs GZ-37 vs GZ-34/5AR4
Date: 20 Jan 1998 02:07:36 GMT
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I have a small “collection” of 5AR4′s here. There is no doubt to me
that the Mullard or Amperex parts are worth the price. Better to spend $25
for a good used part that will last forever. I’ve had several Chinese parts
short or emulate a meltdown. I’d hate to loose a power transformer.

The GZ37 is a beautiful tube, but is very tall and won’t fit in most
integrated amps. It also won’t make it under the cover of Dynaco stuff if you
like keeping the cage on. Lastly the 3 amp filament rating may tax the Dynaco
transformers a bit more than you’d like to. Dynaco does say that the 5U4 is
an ok substitute in a pinch – and that is a 3 amp filament, but I’m a bit
cautious. The Dynaco stuff runs rather warm regularly.

The GE/Sylvania large bulb version of the 5AR4 is also fine, as are
the Japanese “X-Top” parts.

Many RCA or other US labeled 5AR4′s are actually Mullard. It is worth
getting to know the construction.

I have several 5AR4′s labeled “Merit made in USA” that look Chinese
and don’t last.

I have a National 5AR4 that is actually a 6106. The 6106 is a very
nice tube actually, but is an indirectly heated 5Y3, and originally a Bendix
part. It is rated much less than a 5AR4 however.

I have also seen 6087′s relabeled as 5AR4′s – they are another very
nice indirectly heated 5Y3.

Lastly I have a few Sovtek 5AR4′s with the dimple top more
characteristic of East German tubes. They seem to work ok, but I haven’t put
much time on them.

>I recently got an amp that had a National 5AR4 in it that I suspect was of
>Chinese origin.