Musicman 4-8 ohm switch
Dave Hoffman
I have had this 212 HD for 20years and have forgotten what the 4 - 8 ohm
speaker switch on the back panel was used for. I believe it was used when an
extension speaker is hooked up but I am not sure. If anybody knows the
answer, I'll be grateful. Also if there's a source for an owners manual or
Xerox copy of one that would be great.
Thanks,
Dave
da...@accutek.com
http://www.accutek.com/~david
Robert Fries
That's what it's for. Use it in the 8 ohm position when you're just using the
built-in speakers. Set it to 8 ohms if you use the internal speakers and a
4 ohm extension cab. The speaker jacks are connected in series on that amp,
unlike a Fender. The manual that came with mine was just a little card
explaining the controls and switches, not really worth having, except perhaps
for collector value.
/RF
"Dave Hoffman" <da...@accutek.com> wrote:
Robert Fries
rfries at netcom dot com
Mike Schway
In article <35403ea5...@news.concentric.net>, nos...@concentric.net
(Robert Fries) wrote:
>
> "Dave Hoffman" <da...@accutek.com> wrote:
>
> >I have had this 212 HD for 20years and have forgotten what the 4 - 8 ohm
> >speaker switch on the back panel was used for. I believe it was used when an
> >extension speaker is hooked up but I am not sure. If anybody knows the
> >answer, I'll be grateful. Also if there's a source for an owners manual or
> >Xerox copy of one that would be great.
> >Thanks,
> >Dave
> >da...@accutek.com
> >http://www.accutek.com/~david
>
>
> That's what it's for. Use it in the 8 ohm position when you're just using the
> built-in speakers. Set it to 8 ohms if you use the internal speakers and a
> 4 ohm extension cab. The speaker jacks are connected in series on that amp,
> unlike a Fender. The manual that came with mine was just a little card
> explaining the controls and switches, not really worth having, except perhaps
> for collector value.
>
> /RF
(Robert: I'm sure that's just a typo and you mean the 4 ohm position for
the internal speakers only.)
Actually, I've seen 'em both ways...either series or parallel-wired jacks.
The series-wired ones can be a real bummer if the shorting "swinger" on
the external jack gets wonky. That's a real possibility if it's been
around for 20 years and someone at a later date decides to use it. When
the ext cabinet is subsequently unplugged, there's a good likelihood that
the jack won't spring back into its shorted configuration, resulting in a
high-resistance connection to the INTERNAL speaker. The OT sees the
jack/internal speaker as a high impedance load (say, 30-50 ohms, or MORE)
instead of the desired 4 ohms.
A good way to test for this condition would be to unplug the internal
speaker and insert a dummy 1/4" plug. Measure the DC resistance across
the plug. You should get something under an ohm. If the DC resistance is
high, then it's time to replace both jacks.
--Mike Schway
=====================================================================
Mike Schway | [visualize your favorite quote here]
msc...@nas.com |
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rfr...@netcom.com
Definitely a typo,the 4 ohm postion for the internal speakers. You've
seen MusicMan amps with the jacks in parallel? I didn't know thay'd
done them both ways. Fenders are in parallel, but I thought all MM's
had 'em in series.
/RF
On Fri, 24 Apr 1998 06:35:37 -0700, msc...@nas.com (Mike Schway)
wrote:
Robert Fries
Mike Schway
> Definitely a typo,the 4 ohm postion for the internal speakers. You've
> seen MusicMan amps with the jacks in parallel? I didn't know thay'd
> done them both ways. Fenders are in parallel, but I thought all MM's
> had 'em in series.
>
> /RF
Nope, at least some had parallel jacks. I've got one on my bench today to
prove it :-) It's a single-12 2165-RP combo. Saw a head-only this a
couple months ago also with parallel jacks. Makes sense that a 112 should
be parallel, so that plugging in an extension would drop it to 4 ohms not
up to 16.
If you happen to have the 4.1th edition of the Pittman book, check out
pps. 682, 683, 684, and 686.
--Mike Schway
=====================================================================
Mike Schway | "A Gibson ES 355-st through two '65 Deluxe Reverbs
msc...@nas.com | now, that's a *REAL* DR Stereo!"
=====================================================================