[HAM] Leslie 122 Amp Question

[David Anderson]

One thing I would add is that it's not too hard to improve on the  
wiring of a stock 122, particularly the way the signal grounds are  
wired.

When I rebuilt mine, I ran the filament wires to the tubes the  
"right" way, as twisted pairs, with one side tied to ground at ONE  
point, and I ran the signal grounds separately, not all daisy-chained  
together with the filament wiring.

I copied something I saw on Bob Schleicher's website: I ran a 16 ga.  
solid bare copper wire straight from the input plug back to the  
center tap of the PT. This gave me a nice, low-resistance ground buss  
and plenty of places to tie to it.

The stock 122 appears to me to be wired the way it is for one reason:  
to use the minimum amount of wire.

Of course, Scott will probably want to keep me honest on this, so  
I'll say that my wiring mods changed it from an amp with very little  
hum/noise at idle to an amp with imperceptible hum/noise, an academic  
exercise, for the most part.

David

P.S. This has NOTHING to do with three-wire grounding, which I don't  
get into.

On Jun 4, 2008, at 1:37 AM, Jim Shanks wrote:

> Hi All,
>
> I have a Leslie 122R amplifier that's been subjected to some very
> creative repair.  Looks like whomever fixed it couldn't find the
> 30/30/30/10 can cap so they just wired in a bunch of 22mf caps.
> Following the schematics, it looks like one of them is even wired
> wrong.  Plus wires were moved from original locations to  
> accommodate the
> mods and other components a just plain wrong.  Not surprisingly, it
> doesn't sound like it should.
>
> Anyway, I have the right parts, and service instructions and
> schematics.  What I don't have is a photo of a 122 amp that's put
> together correctly.  A picture or diagram would be real helpful in
> properly placing the correct components as well as getting the right
> colors on the wires.
>
> Anyone know of a source or have a high res digital photo of the
> underside of a 122 amp?
>