[Vintage-Audio] 7591 replacements

Tue Jun 4 17:20:01 2002

There is / was NO mil spec. 6L6, at least post 1940's. The mil spec version
of this tube is the 6L6-WGB / 5881. This type was developed by Tung-Sol and
has specs that surpass those of the generic 6L6 types. The ( civilian )
6L6-GC has different specs ( more electrically rugged ) than earlier
versions ( G / GA / GB )and is equivalent to the 7027-A, another hard to
find type. The 5881 is the preferred replacement for ALL 6L6 family tubes,
including the 7027-A
The 7591-A was ( is ) a unique type. This is the reason that they are
un-available, and hard to sub. The only types ever produced that have
identical specs were the 6GM5, and the 7868, both of which have different
pin configurations / basing.
These tubes were used in only a handful of models produced near the end of
the vacuum tube era by such makers as Fisher, H.H. Scott, McIntosh
( MC-225 ), Sherwood, and in a few guitar amps, mainly Ampeg. The reason
that these 7591-A types are so hard to find ( it has been rumored ) is that
a group of "Oriental Gentlemen" cruised through the USA several years ago,
and bought up all that they could find.
-----Original Message-----
From: Helmut Usbeck <[email protected]>
To: [email protected] <[email protected]>; Duane
Fischer, W8DBF <[email protected]>
Date: Tuesday, June 04, 2002 2:55 PM
Subject: Re: [Vintage-Audio] 7591 replacements


>On Tuesday 04 June 2002 14:22, Duane Fischer, W8DBF wrote:
>> The 6L6gt/gc was mil spec, was it not? Much larger and I think the
>> amplification characteristics were somewhat different.
>>
>> Duane W8DBF
>>
>>A 6L6 is a 6L6.  Don't know what you mean by mil. spec.  The GT meant
glass
>tube, don't remember what the gc was, the ga has an ST type envelope, the
>original 6L6 has a metal envelope.  If a 6L6 was produced for the military
it
>bears a JAN designator.  Which there probably is.  One thing to keep in
mind
>is that JAN or mil spec components aren't what they're cracked up to be.
>They just meet the requirements that they wanted for a part.  Not
necessarily
>"better" than it's normal production counterpart.  If a 6L6 would have done
>the job for the HI-Fi factories they would have used it instead of a 7591.
>--Helm.
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