#1
I've got an OLD Fender Pro Reverb (Silverface, mid-70s) which is, as far as I can tell, in pretty decent working order. The only issue is that the output over the external speaker jack is VERY quiet, even with the internal speakers disconnected (initially I had assumed the additional speaker was adding too much resistance). The same external cabinet plugged in to the main speaker out sounds just fine, so the cabinet's good.

Anybody got any suggestions?
#2
Quote by taintsauce
I've got an OLD Fender Pro Reverb (Silverface, mid-70s) which is, as far as I can tell, in pretty decent working order. The only issue is that the output over the external speaker jack is VERY quiet, even with the internal speakers disconnected (initially I had assumed the additional speaker was adding too much resistance). The same external cabinet plugged in to the main speaker out sounds just fine, so the cabinet's good.

Anybody got any suggestions?


I'm confused between the red part and the blue part.


Originally, I was going to say that you can't have an external cab at the same time as the internal - but I did not verify that. Free bump.
#4
Depends, my traynor an blues deluxe have an output for a matching external cab, and can use both at once, so long as the second cab is 8 ohms.

I also vote for dirty contacts in the jack. Probably lightly rusted or patina has formed over the years.
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Last edited by Reincaster at Jul 29, 2011,
#5
I can't really see inside the jack to tell if it's rusted, but this isn't unlikely. The guy who gave all this stuff to me kept it in a loft in his garage for years, and I hadn't tried to use the external out for the better part of a decade.

For now I guess I'll try and plug/unplug a cable into it a few times to scrape off some of the gunk and see if that helps.

On the bright side, the cabinet has a volume pot, so if I leave the amp's internal speakers disconnected and plug it into that jack, I can crank the amp up past the break-up point without having the neighbors beating my floor with a broomhandle.
#6
Quote by taintsauce
I can't really see inside the jack to tell if it's rusted, but this isn't unlikely. The guy who gave all this stuff to me kept it in a loft in his garage for years, and I hadn't tried to use the external out for the better part of a decade.

For now I guess I'll try and plug/unplug a cable into it a few times to scrape off some of the gunk and see if that helps.

On the bright side, the cabinet has a volume pot, so if I leave the amp's internal speakers disconnected and plug it into that jack, I can crank the amp up past the break-up point without having the neighbors beating my floor with a broomhandle.


A good way I've found to scrape rust or grime off a jack without having to remove it is to get one of those 9mm brass brushes for cleaning 9mm pistols, and ram it through the jack a few times, takes all the crap off of it.
#7
what external cabinet are you using? what is the external cabs impedance?

sounds like an issue with the external speaker jack in general though. i'd take it to a tech if the cleaning doesn't work if you want to use the function.
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#8
dust and corrosion in the jack because it was never used.


clean the jack.

edit: also, never, never, never unplug the internal speakers in a fender, even when using an extension cab via the extension speaker jack. fer serious.
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Last edited by gregs1020 at Jul 30, 2011,
#9
@gumbilicious - the cabinet in question is an old Kustom 2x10, I'm not sure what the impedance is on it, as it isn't listed on the back and I haven't had the gumption to take it apart and see what speakers are in it and how they're wired. I also tried it with an equally old Gibson cabinet (from the look of it, also a 2x10) to the same effect.

@gregs - any particular reason *not* to unplug the internal speakers? It seems to be working fine with the external cabinet plugged into the main speaker jack (though i've only had it running like that for a total of about half an hour).
#10
Quote by taintsauce
@gregs - any particular reason *not* to unplug the internal speakers? It seems to be working fine with the external cabinet plugged into the main speaker jack (though i've only had it running like that for a total of about half an hour).

i'm talking about not using the main jack and only using the extension jack.

plugging into a cab from the main jack should be fine.

i should have stated, "don't run it with just the extension cab speaker out".


did you clean the ext speaker jack yet?

also mismatched impedance isn't good, figure out what the cab is rated at.
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#11
The jack is cleaned. I'll have to take the cab apart to figure out the impedance.

Thanks for the clarification on the internal speaker business - I was starting to worry I was destroying the beast.

edit: Just took it apart, the speakers are...odd. Square magnets, 8-16 ohm. I've never seen speakers with a *range* of impedance. They are wired positive of speaker A to negative of speaker B, so I should have a maximum of 8 ohm ( 16 ohm/2, though it has been a while since I've dealt with this kind of thing, so I could be wrong).
Last edited by taintsauce at Jul 30, 2011,