Re: Walsh & Supers

"Lord Valve" <detritus@xxxxxxxxxxxxx> wrote in message
news:435BFA55.21C8A12F@xxxxxxxxxxxxxxxx
>
>
> Don Evans wrote:
>
>> "Don Stefani" <don.stefani@xxxxxxxxx> wrote in message
>> news:1130098746.703419.237980@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> > To quote a 1988 Guitar Player mag article I found online:
>> >
>> > Joe Walsh: "...That would go into a pair of Fender Super Reverbs with
>> > four 10s, except only one top. I would put them on metal folding chairs
>> > that are about knee-high. Standing about eight to ten feet in front of
>> > those, you can actually move around and find different areas to sustain
>> > any note that you want. It's also incredible because eight 10s pull the
>> > impedance of the amp down to like 4 ohms, and that's where you really
>> > get your sweet sound--when the amp is screaming before it blows up."
>> >
>> > So he was playing one super through 8 10's?
>> >
>> > So that leads to the "before it blows up" thing?
>> >
>> > What is mechanically / electroniclly going on here?
>> >
>> > - dstefani
>> >
>>
>> He was a little off on the impedance, unless he was running in series
>> parallel. If he just plugged the extra set of tens into the external
>> speaker jack, he was at 1 ohm, or 50% of the rated impedance needed by
>> that
>> amp. Definitely a "before it blows up" scenario.
>
> Wrong.

Which part ... the one ohm load or the 50% impedance? I read your other
post and you state that two speaker sets from two Super Reverbs, because of
inefficiency of the wiring would yield a 2 ohm load. All we are talking
about is one speaker connector from the external jack to the plug attached
to the other speakers, yes? Are you saying the load from each set of
speakers is really 4 ohms and the load equals 2 ohms when hooked up in
parralel?

>
>> If he was actually
>> running each parallel group of tens in series, he would be running at 4
>> ohms, or 200% of impedance the amp was designed for. Probably not quite
>> as
>> bad, but not healthy either.
>
> Wrong. Backwards.

Ok, so it's worse to run at twice the load than at half the load?

>
> Consider why a Fender amp is wired so that when the speaker
> plug is removed from the output jack, a *short* is thrown across
> the OPT secondary. There *is* a reason.
>
>> For the record, many years ago I ran my Super
>> Reverb hard for a few months with an external 4 ohm cab, and it survived
>> and
>> runs fine to this day.
>
> A 100% upward mismatch is usually tolerated by older Fenders.
>

I wasn't totally clear, I guess. I ran all of the speakers ... the external
cab and the internal speakers together. I believe that adding a 4 ohm load
in parallel would actually be a downward load. Six eight ohm speakers
instead of four.

These days, I frequently run my Super into a four ohm load by disconnecting
two of the internal speakers. Two tens in a big cabinet is a good thing
IMO, and I do get to run the amp harder.

> If that had've been an 8-ohm box (assuming it was the only load)
> you would have arced a tube socket - or worse. I've also seen
> arced sockets with a 4-ohm load on a SR. When operated into
> lower impedances than rated (even a short) the wiring and the
> OPT secondary become the load - and the secondary in a
> two-ohm OPT is *designed* for high-current loads. No problemo.
>
> Lord Valve
> Expert
>

Thanks for letting me know that. I used to worry about it a little.

Don
>
>
>>
>>
>> Don
>
>


.

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