Adding a simple speaker jack to a combo

[YeRedHouseOverYonder]

So, I just picked up an older amp that has the alnico speaker directly soldered to the wires from the OT. There's no speaker jack whatsoever. I want to add one in order to hook up the amp to a powersoak and play it without causing issues since I live in an apt. Would I just need to solder the hot/ground to the corresponding +/- from the jack? Would this be a simple mono jack (switchcraft #11)?

I would prefer to this on my own if it's "simple". If not, I suppose I can pay a tech to do it and check the amp thoroughly while he/she is at it.

Edit: Amp should be here by Thursday.

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[Darg1911]

Re: Adding a simple speaker jack to a combo

Maybe 2 jacks. One output (amp out) and one input (to internal speaker). Disconnect the OT from the speaker terminals and wire it to one mono jack. Wire a second mono jack back to the speaker. Output jack to power soak ... Power soak out to input jack. That allows you to use the amp directly, or with the power soak, into an external cab or back into the stock speaker. If you want to use the speaker in the amp without the power soak, just use a short jumper from the output to input jack. The only "danger" comes from forgetting to jump the input and output if you aren't hooked up to the power soak and/or an external cab. But without going to switches, it's probably the easiest solution.

 

[YeRedHouseOverYonder]

Re: Adding a simple speaker jack to a combo

Gotcha. I have a monster speaker cable with female connectors and a male plug. I'll just end up using that instead of the second jack. I'm use to and take caution with the amp out and speaker being connected. Thanks!




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[Darg1911]

Re: Adding a simple speaker jack to a combo

That'll work. Just be careful with those old speaker terminal tabs if you're going to be disconnecting and reconnecting to them a lot.

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

For sure. I think it's an old RCA Alnico 12" Speaker. Not original, but it's the reason why I got a good deal on it.


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[jeremy]

Re: Adding a simple speaker jack to a combo

yes its that simple, looks like a fun amp. looks to be singled ended in the pic, yes?

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

^^ I'm hoping it turns out that way. I was looking into a 5e3 clone or a Bogner New York, since I'm moving out. I can't justify a 50w Combo anymore. Luckily, ran across threads stating that these older Gibson GA amps are sleepers. They're about the same price I'd be paying for a kit/built clone/Bogner New Yorker.

This one is a '55-56 GA-6 with 12AY7, 6SL7GT, 5Y3GT, and 2 6V6GTs 10-14w. Gibson's take on a Fender 5c3. They're described as warmer tweeds with some sounding better, as good, or close enough at a fraction of the cost. Tubes, Caps, Iron, Chassis are original. Recently serviced. I don't think the enclosure and old RCA speaker are stock. I managed to get it cheaper than the asking price.

https://youtu.be/U1M9QXWnv2g
https://youtu.be/SrI3FSK1u9A



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[jeremy]

Re: Adding a simple speaker jack to a combo

could only see three tubes in the first pick. very cool amp, ive played a few old gibsons and they are cool amps for sure. a little different than fenders but comparable all around. a little cleaner and warmer typically but fun amps for sure! enjoy it

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

You're good, I zoomed in on the photo to show the OT wired to the speaker. Thanks for the heads up, can't wait to play it


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[GoldenVulture]

Re: Adding a simple speaker jack to a combo

Has it got any hum or crackle ?

 

[Darg1911]

Re: Adding a simple speaker jack to a combo

Cool amp. Quick tip ... if you ever end up having to hunt down a microphonic tube, start with the 6SL7. They are notorious for it. I find that the short plate 6SL7's tend to be less susceptible. Like the JAN 6SL7WGT's. Not cheap in general but can be with some patience and maybe a little risk (on fleabay).

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

No noise that I know of. The amp will arrive tomorrow. The seller on Reverb said that it checked out fine when he took over to his tech and added a 3 prong cord. He reported no issues other than the non original parts.

Darg1911, funny that you mention the JAN 6SL7WGT. The tube dealer I get my NOS tubes from recommended me the same tube. I went ahead and bought it with other quality NOS tubes. It has original RCA 6V6GTs and a Kenrad 6SL7GT. Won't know the other tubes until it arrives. I also went ahead and bought the mono jack yesterday. Thanks for the help guys!


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[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

Update: added the jack and switched out the speaker for a Celestion Alnico Cream. It increased the headroom and volume by a lot. With the old speaker, I was able to crank the amp up with out worrying too much. Can't do that anymore haha. So far, my favorite tones are coming from input 1 (warm woody clean tone) and the mic (raunchy tweed goodness). *I do need to add a bracket to mount the jack properly.

'55 Gibson GA 6 (dated the IRC pots ending in 516)

As far as future upgrades, I know that in an amp this old, I need to change out the original filter caps and more than likely some carbon comp resistors. *I think the cathode bias resistor(?) is pretty much toasted. Doesn't look reliable. I'd rather switch out caps and resistors rather than the original PT or OT.

Do you guys have any recommendations for brands? Looking at F&T *filter caps. If I need up needing to replace the CC resistors, would it be smart to measure the amount of drift they had and adjust the values a bit? What material would be best? *I'm reading that CC resistors are only beneficial as plate resistors. I found some nice repro coupling caps (Jupiter) that sound close to astron mustard caps. Any tips, pointers, or help would be appreciated. Don't think I should start a new thread.


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[Darg1911]

Re: Adding a simple speaker jack to a combo

Personally, I'd leave the coupling caps unless there is a problem. I'd also leave those carbon comps unless your getting some noise. That bias resistor would get replaced. If it aint humming and the PS caps measure within tolerance, I'd probably leave them but that's probably not sound advice. Besides, they probably are out of spec. My concern would be changing the tone and mojo. Going crazy is going to change the tone some but maybe not for the better. I'm not a tech and my input here likely isn't considered universally good advice but I recently had an eye opening experience from doing some tweaking in a small SE amp. The differences in tone from different resistor types (not values) surprised the hell out of me. All I'm getting at is to go slow. Sound check between small changes so you know what accounted for the change just in case that change is for the worse.

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

^^ I hear you. With a design and layout this simple, I am very tempted to jump in and do the mods myself. Slowly. I'd also prefer to keep it as stock as possible. Not to collect, but preserve the charm of the amp.

From reading multiple threads on various forums, they are a couple schools of thought behind the mojo in old amps. Some think it's the components (old caps and CC resistors), the irons/speakers, and the actual drift values from parts that have gone out of spec.

I'm getting some rattle on the g string when it's cranked loud. Thinking there's a tube that's going bad. I got the NOS tubes. Debating whether to switch them out slowly or all at once.

Thanks for the input.


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[GoldenVulture]

Re: Adding a simple speaker jack to a combo

Try changing your pre amp tubes one at a time and the different ones you have [ presuming they're of the same type ]. Some tubes seem to work better in some positions better than others. Your filter caps are very old and most likely flaky at best. I'd change those.

 

[YeRedHouseOverYonder]

Re: Adding a simple speaker jack to a combo

^ Thanks, will do. I agree about the caps. That's why I've been looking into replacement parts. I know for sure that bias resistor has to go.


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[GoldenVulture]

Re: Adding a simple speaker jack to a combo

Check out this place. - https://www.tubesandmore.com/products/capacitors?filters=Type=Electrolytic -

 

[YeRedHouseOverYonder]

Adding a simple speaker jack to a combo

Update: Finally got around to taking this to my tech. Got the filter caps and bias resistor changed. We went with F&T caps and a ceramic bias resistor. Added a bracket for the jack that was added. My tech went over the components and found two plate resistors (V1) that drifted about 65-90K. The rattle I was hearing was from the bell from the Celestion Cream Alnico. The 6SL7 was making contact with it. Went ahead and removed it, no more rattle. All the tubes are working well. Cranks well in the mic channel and no longer have to worry about it \m/ She's all set for a good minute.

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