Tube & Tube Tester Recommendations?

[Brian Carling]

IN many circuits you can SUB a 6L6 for a 5881, but NOT ALWAYS!

I am sure they will sub fine as a class C RF amplifier stage, but for audio
outputs, you can't always. It appears to depend on whether they are being
run Class A or B - or somewhere between.

I once tried the substitution in an audio power amplifier using fixed bias,
and the result was pretty awful.

Ih recent years the Russians and East Europeans etc. have been hawking
5881 and 6L6GB/GC/WGB etc etc. as being the SAME. In fact they may be
selling the same tubes and MARKING them as being a 5881.

In fact the original 5881 tubes that were sold by G.E, WestingHAUS and
their ilk, were a smaller tube than the 6L6. At least the bottle was shorter,
and fewer audio amp manufacturers used the 5881.

My experience with these came with servicing public address sound
systems, guitar amplifiers and that sort of thing. A few hi-fi amplifiers also
used these tubes. Typically a pair in push-pull will get you about 10-15 watts
of smooooth Class A or 40-50 watts of Class AB / B.


On 27 Dec 99, at 17:04, DavidC wrote:

> I am starting the process of going through my BA's.
>
> I need your good counsel on tube substitutions and a decent
> inexpensive and reliable tube tester.
>
> A specific question: Are a pair of 6L6's a good swap for the 5881
> modulator pair in the Elmac AF-67?
>
> Here are the rigs and their tube lists.  Any good hollow state or SS
> subs jump out at anyone?
>
> R-392
> --------
> 6AJ5
> 12AU7
> 26A6
> 26A7/GT
> 26C6
> 26D6
>
>
> Morrow pair
> -----------------
> 6AQ5
> 6AL5
> 6BE6
> 6BJ6
> 6BZ6
> 6C4
> 6T8
> 12AT7
> 12AX7
>
> Elmac AF-67
> --------------------
>
> 6AK6
> 6AG5
> 6AQ5
> 6AU6
> 6BJ6
> 12AU7
> 5881
> 6146
> OB2
>
> Elmac PMR-6
> ---------------------
>
> 6AL5
> 6BA6
> 6BA7
> 6BE6
> 6BJ6
> 6BK5
> 6C4
> 12AT7
> OB2
>
> M-1070 PS
> ----------------
>
> OB2
>
> - Thanks! & 73, DavidC  K1YP
>
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