Adding an external speaker out to vintage amp question.

Scooter B

Scooter B

New member
I have a 1960 Kalamazoo (Gibson) Model One 5 watt tube amp that has some pretty awesome tone and perfect for my home recording volume wise. All 100% class A desong with three tubes....the budget part of this Gibson line is the cabinet is made or particle board.

The only weak spot is the speaker wich while good for reproducing more vintage sounds starts to break up a little at higher volumes.

Personally I prefer the distortion in the tube gain and not from the speaker its self for more modern tones. Also the paper cone being 40 years old and of unknown history (recent e-bay find) may not be long in life when cranked. The serial numbers on thses are printed on the speaker backing for some reason so I would prefer to keep this speaker in good shape and add an external jack that switches the internal speaker off when a 1/4 inch speaker plug is inserted.

I found some recomended mods here and plan to do the grounded plug and the external speaker jack projects (yes I know to discharge the caps first) here.

http://www.rru.com/~meo/Guitar/Amps/Kalamazoo/Mods/speaker.html

External Speaker Jack
As an alternative, you can leave the current speaker permanently wired, with a jack that switches the internal speaker out when an external speaker cabinet is used. This is an even better alternative, because it doesn't provide a chance to run the amp without a speaker (which will unusually fry your output transformer).
Wire the OT and speaker grounds (return) to the ring (outer connector). Wire the other OT lead to the tip connector. Wire the other speaker lead to the switch connector. When no plug is in the jack, the switch will close against the tip connector, letting your internal speaker work. When you plug in the cab, it opens that switch, disconnecting the internal speaker, but leaving voltage across the tip and ground, where the cab's plug is connected.


The directions are not very specific to me as someone who knows just a little about wiring but knows how to solder etc. But the attached diagram shows wires going to a jack with a tip and ring (I assume this implies a female TRS jack?).

While looking at the female TRS jacks at partsexpress.com they have "swiching" jacks and "non switching" jacks.

1. Do I want the switching jacks for this purpose?

This seems to make sense but I have not used swithcing jacks before.

2. If this uses a TRS does the sleeve get wired to anything?

I am assuming form the description that the sleeve does not get wired but they may be assuming I know more than I do and would be crazy enough to do this myself if I didn't.

3. Lastly the internal speaker wire is wired to the switch? Is this seperate from the sleeve?

Thanks
 

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I found a Kalamazoo model two at a rummage sale a few months back, I agree they are kicking little amps. I debated putting in an external speaker jack, then decided to keep mine stock, somewhere I heard they are rapidly becomming collectors items so I didn't want to risk hurting it's resale value. I only gave $20 for mine and have turned down offers for considerably more.
 
If you want to use an external speaker, why not just hook a female 1/4" to the existing speaker cable? Then you hook a male 1/4" to the original speaker, and use a regular speaker cable for your extension cab.

No mods to the original chassis, no switching jacks, the amp can be used either way very simply, and put back to stock in about twenty minutes.

Just make ABSOLUTELY SURE the amp is off before switching, either way.
 
If you want to use an external speaker, why not just hook a female 1/4" to the existing speaker cable? Then you hook a male 1/4" to the original speaker, and use a regular speaker cable for your extension cab.
Click to expand...

Thanks easychair

That is another option but there is a risk of accidentally running the amp without a speaker hooked up wich can fry the amp.

The switched jack method ensures that the internal speaker alwasy remains hooked up unless another speaker is plugged in (well for the most part). I suppose someone not too inteligent could plug an plain cable into the jack and not have a speaker hooked up on the other end....so there is no guarantee just better odds I think with the switching jack.

The diagram shows wires going to three places a tip, ring and switch (no mention of sleeve). The only switched jacks I have found are unbalanced/mono which would only have a tip and sleeve with no ring (TS).

I know the guitar cord jack of course is a TS but is the female 1/4 jack that mounts to the cabinet supposed to be a mono/unbalanced/TS or a stereo/balanced/TRS jack?

Dani that was a fantastic deal....I never find them that good but I got my for $100.
 
Why not just replace the speaker? Keep the old one for if you ever want to restore it to "vintage", but if you drill the chassis, you've blown that, anyway. I replaced the 8" original speaker in my ancient Supro single ended 6V6 amp with one from Kendrick, and it sounds great.
 
Why not just replace the speaker? Keep the old one for if you ever want to restore it to "vintage", but if you drill the chassis, you've blown that, anyway. I replaced the 8" original speaker in my ancient Supro single ended 6V6 amp with one from Kendrick, and it sounds great.
Click to expand...

That is also an option however I like the vintage sound for clean to mildly distorted that comes out of the stock speaker for some things and I want to preserve the condition it is in.

Plus I also enjoy wood working projects and want to design a new cabinet that will incorporate two features.

1. A removable back panel that allow closed back and open back options.

2. DIY isolation box that works with the cab.
 
Adding external speakers....

I've been using 2 fender princeton stereo chorus amps (the old red knobs) in series to achieve a 4x10 (2 pairs of 10's in stereo), I'd like to add external speakers (1 left, 1 right) to achieve my 4x10....(again, 2 pairs of 10's in stereo)..... as there is no outlet or jack...Anything special I should do, or do i just add 2 jacks?
 
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