Re: [Harp-L] SS to tube rectifier

["The Bernadettes" <mdestefano@xxxxxxxx>]

Hi Larry,
    The best approach would be to use a Weber Copper Cap rectifier, which is
a solid state rectifier that mimics the sag and voltage drop of a tube
rectifier ( there is a 5R4 type Copper Cap).  Installing a real tube
rectifier would require also installing a tube socket and a 5 volt filament
supply transformer.  First, I must say that this is not a job for an
amateur, you'll have to deal with a high voltage power supply and if you're
not familiar with the safety procedures involved, you're better off taking
it to an amp tech.  With the Copper Cap approach, you can use a module type
which doesn't require installing an octal socket.  If your chassis does have
an unused octal socket hole cut-out, then you can install an octal socket,
then you could use an octal type Copper Cap which would be prefered cuz it
would allow you to experiment with different Copper Cap rectifiers very
easily (some Fender amps that use SS rectifiers, frequently have unused
cutouts which are covered by a small metal plate.)
    About the 68 Bassman, these amps have a lotta issues with them which you
may want to address also, such as a weird biasing scheme, and other
circuitry that most amp techs usually modify to a standard blackface type
circuit.  Not that there's anything wrong with the amp, in fact, these
Bassman heads are highly sought after by amp hot rodders, they make great
candidates for modified/hot rod amps.  You just might also want to look into
some other mods also besides the rectifier issue.  I don't have time to get
into specifics, but I probably know dozens of cool mods that would enhance
such an amp for harp.

You can always try contacting me off-list for more details.
Hope this helps,
Don D.



----- Original Message ----- 
From: "Larry Ravlin" <sheepdip@xxxxxxxxxx>
To: "Harp" <harp-l@xxxxxxxxxx>
Sent: Wednesday, August 11, 2004 3:48 PM
Subject: [Harp-L] SS to tube rectifier


> Gentlemen,
>
> I'd like to change the SS rectifier in a 68 fender Bassman to the 5R4 tube
> rectifier.  Has anyone on the list done this or have any info on the
change?
>
> Larry
>
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