hey Capn.... Look what I got

capnjuan

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tele4tone said:
... So......$180 was a good deal? haha ... The speaker seems strong, but I wonder where I can get a new one for a back up. When the original goes I will need time to get it reconed.
You did very well!

I was looking around for some information on your speaker and found This thread over on the Gear Page. I was a little quick to ID your speaker as a field coil. In addition to the Jensen mfr ID code 220XXX, is there another code on the rim of the speaker; for example P12R or P12Q? If you have only 3 wires leading to the transformer and two wires going to the speaker, then you don't have a field coil speaker; that's the output transformer that's mounted on the frame. How many wires to you have in/out?

Older speaker frames commonly had flanges with drilled holes allowing for the OT to be mounted on the frame; I don't think any newer ones do. If/when you want to mess with a spare or replacement speaker, you are going to have to deal with that OT. Not too long after your amp was made, Gibson went to mounting the OT on the chassis. If you want to use a newer speaker, I think you're going to want to look into having the OT moved to the chassis - not really a big deal ... just some drilling, bolting, and shortening of the transformer leads.

If you have a standard OT on the speaker frame and get it moved, you can do whatever you want in the way of speakers. In their day, those Alnico 5 speakers were at the top of the speaker food chain.
 

capnjuan

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Close-up pic of the speaker and the chunky thing mounted on it would be nice too. 8)
 

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Three wires in two out. Alnico 5 Speaker!!!!!! hahaha I can't believe I didn't catch that after you explained the field coil. I know that Alnico was a type of magnet..... Thanks and a pic will follow

Jeff
 

capnjuan

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Hi Jeff: pics of a couple of Jensens made a few years after your amp when Jensen was still making their frames to accommodate speaker-mounting of output transformers. I don't know when they stopped but later models aren't pre-drilled and dished like these.

58Jensensbracket.jpg



If you can find an older 12" Jensen / Oxford / Utah frame that accepts mounting the OT; yippie ... you can get it re-coned for $50-odd and move the OT to the stand-in speaker while you get the Jensen re-coned if/when it needs it. If you do, get the speaker shop to test for voice coil rub ... it can be subtle ... and if it needs it, get it replaced.

Those Alnico 5s are highly sought after and go for big money on eBay ... '57 Alnico 5 re-coned; OT-ready ... (no speaker bell ... will not hit top dollar) and a 1960 P12N ... mounting holes gone. I have a black frame '60 P12N like the eBay P12N in my Gibson GA30RV :mrgreen:

If you start looking for a handle, check out Mojotone. There used to be a guy out there who made the real thick ones that are much closer to the original. Not sure if he's still out there or not.

Have fun with it!
 

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Pity me! I'm reading this on my phone, and the houseband on this scow is playing through ss Peavys.
 

capnjuan

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tele4tone said:
...That is clean....and recovered.... I'll keep mine original.
Hi Jeff: it is clean ... I'd keep yours original too ... but the amp above which is linked from the GearPage ... the tolex matches the '58 version shown below. (page 86, Gibson Amplifiers 1933-2008, Wallace Marx) If it's a recover, it was done a while ago ... that Gibson 'tweed' - patterned cotton bonded to clear vinyl - has been off the market for quite some time. No ... don't mess with yours! :)


MarxGA20.jpg
 

capnjuan

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Hi Jeff; pics of my '59-'62 GA20T ... like the one on the right in Marx' pic above. When I got it, it was covered in paint ... the best I could do; diluted orange shellac for color and several spray coats of matte urethane:

front09.jpg



That's a re-coned '59 Jensen C12Q ... compares to a Weber 12F125 ... a 6087 military-grade 5Y3 rectifier, and a pair of Bendix 5992s on the left. I've been switching back and forth between RCA and Sylvania 5879s ... some say one sounds better than the other ... I can't tell much difference.

back06last.jpg



This is how I solved mounting/connecting new power supply caps; slung between wiring strips. If or when the need to be replaced, they can just be snipped out and new ones soldered in instead of coming up with a scheme. Yours are nicely done ... nothing wrong with them ... I'm just not a big fan of bundling. No big deal ... showing off my own work ... not criticizing your amp:

capsps03.jpg



In your amp and mine, channel 1 was set up for a microphone. It has capacitor inputs at both jacks with a 10meg grid leak (bias-setting) resistors. I bought the amp because I wanted a 5879 amp but, at least to my ears, channel was useless so I re-arranged mine to mimic a standard 'tweed' amp front end.

The input caps were on the underside of the board. I replaced the cap with a 56K grid stopper resistor, replaced the 10meg ohm grid leak resistor with a 470K resistor, and bumped the cathode resistors from 680 ohm to 2.2K. I also bypassed one of the two cathode resistors with a 25uf/25V cap so the channel would get away from the squishy thing, generate a more tweed tone, and I'd have two different voices at the two input jacks. The busy look comes from the grid leak and cathode resistors going back to a ground point on the top of the circuit board.

channel1.jpg
 

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Channel one has a little more break up and sizzle on mine. Is yours labeled Microphone? Mine is labeled Instrument 1, Instrument 2. I really prefer channel one to channel two. Maybe It has the wrong tubes in it.. I never checked :)

Channel 2 is a little cleaner and I like to use that when I need such. I may rig this up with an A/B box for that purpose. I know I could sell this and make a little cash, but I have a hard time wanting to.

I honestly need a head in this same format so I can send the amped signal to an off stage cab and keep stage volume down. Nobody wants to hear cranked 6v6's in worship service....... But it sounds so good. It is a fantastic little amp. I like it more than my friends '68 deluxe reverb.

Cap'n what is best to clean the painted panel without removing the paint? I have some surface corrosion on the panel and the speaker bell cover.

Thx, Jeff
 

capnjuan

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tele4tone said:
Channel one has a little more break up and sizzle on mine. Is yours labeled Microphone? Mine is labeled Instrument 1, Instrument 2.

Hi Jeff: the Gibson service manual for the model ID's channel 1 as mic but ... never say never with Gibson. Without dragging you through the technical break-dancing, unless the seller up-dated the channel 2 5879 cathode caps (underneath :evil: ) .. the electrolytic bypass cap is a little tired out. Or the 5879 is going microphonic ... a common shortcoming in that tube and its cousin the EF86 adored by Vox fans.

I honestly need a head in this same format so I can send the amped signal to an off stage cab and keep stage volume down. Nobody wants to hear cranked 6v6's in worship service.......

Mad Dog's killer Garnet would be perfect!

But it sounds so good. It is a fantastic little amp. I like it more than my friends '68 deluxe reverb.

Welcome to the world of Gibson tone love ... not as much headroom but warmer and fatter than Fender ... it's about cheese ... some prefer Swiss, others prefer Gouda.

Cap'n what is best to clean the painted panel without removing the paint? I have some surface corrosion on the panel and the speaker bell cover.

Warm household soap and water on a damp rag ... not enough moisture to get down in the controls. Even better, use Q-tips around the shafts of the controls. If you have a chopstick, cut the end so it's beveled like a chisel; hold it at about a 45 deg angle and try and 'chisel' the corrosion off. The best you'll be able to do is get the surface stuff off.

Don't be fooled by these Gibson-labeled chickenheads. They are NOS but aren't what you need and are a dime-a-dozen anyway. Cheers!
 

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yeah........ :oops: I already bought some other ones that didn't fit..... :roll:

Jeff

Dakaware never got back with me. I don't suppose they are interested in a quote for 5 knobs
 

capnjuan

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tele4tone said:
a little late but as promised.
Sweet! 18th week of 1956 ... the speaker's older than half the membership here :p If you ever find yourself a little ahead on cash, you might consider pulling it, putting in a new something-or-other, and put the Alnico 5 away for safekeeping. If you ever wanted to sell the amp, it'll bring a little more with that original speaker intact.

Knobs; just let me know, I can fix you up with some more that don't fit just as well :wink:

Cool speaker 8)
 
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