Looking at Amps today

[rafe]

An early les paul GA-40 (54?) and an early GA-50t. the les paul is in pretty nice(OK) cosmetic shape the 50 is a bit tattered and missing the 8 inch and a 6v6. They otherwise look complete. He has set a price that He won't move from and it's not cheap but not outrageous, they haven't been plugged in in decades. I want to pull the chassis (look under the hood) I know they will need some work but I'm probably going to pop I'm not looking to flip these. They may be a bargain though in the long run.

{EDIT- images don't work in subject line, moved to message --PRR}

[rafe]

I picked up both amps today within 2 miles of my home. The should both clean up nice. Look unmolested and are both early 53 from what I see so far (speaker and tube codes) Very happy GA-40 and GA-50t Both cabinets will clean up well Some cover reglue on the 50t. I can hardly wait to recap them and use them.  MWBR funny thing is they were on the Gibson amp forum (Ben Prevo) which is worldwide and there are usually no ads allowed but Ben allowed it (Thanks Ben)

[sluckey]

This sounds like a lotta fun! Please share with us.

[bmccowan]

Nice!!! I have a 1953 GA-40. Had a tough time getting the trem working - its a strange one. A couple of folks here helped me with it - there is a thread.
And man I want one of those GA-50s - Coolest cabinet ever!

[Rontone]

And man I want one of those GA-50s - Coolest cabinet ever!

They are nice, what kind of covering is on those, its tan with a nice pattern on, it give it the looks of wood veneer

I've just seen of the GA-40 Les Paul editions amazing baffle work and woodwork with the LP signature on the front

[bmccowan]

Its hard to find cover material that matches, as they did not use Tolex brand. Closest I have seen is searching fabric stores and bookbinding supplies. Mine has the LP signature grille intact, which is nice, but the rest of the covering has some creative electrical tape repairs that I need to deal with someday. I also have one of the next version of the GA-40 LP when they switched to 9 pin preamp tubes 5879 and 12AX7. I actually bought it from a shipping company that smashed it up pretty good. The original buyer refused the shipment and the shipper's insurance co. sold it to me for an insanely low price. I had been the second highest bidder at the auction.
Have a blast!

[rafe]

"They are nice, what kind of covering is on those, its tan with a nice pattern on, it give it the looks of wood veneer"


It's a thin cloth coated with (possibly paint?) I have been going over the back (removable) panel and gluing it back down that came out good there is a lot of areas missing on the amp cabinet (redwood by the way) I will glue it back for now. and then focus on the noisemaking parts. The les paul GA-40 is going to be the priority, but is going to need a good going over it looks like the surround on the speaker has seen better days ....It might need a new surround or a recone I'll try to upload photos as soon as i get them. I have to e-mail them to myself.

[bmccowan]

This stuff is pretty darn close: https://hollanders.com/collections/buckram-library-summit-bookcloth/products/library-summit-brown-new?variant=43990461350192
It used to be available in many more colors.
Folks on the Gibson Forum may have some better sources?
I tend to leave my old amps tattered, waiting for the relic amp craze that's bound to happen some day

[rafe]

1953 GA-40

[Rontone]

I'll ask my friend, he works in a nice library that do some work on antique books and manuscripts, occasionally working with some very old pieces, working with vellum etc,

And wow, are those all original type tubes in there too? I hope to use some of those older type bases one day, make a proper early 50's or 40's style amp

[rafe]

from the date codes they all (except the green scripted one on rt.) appear to be original that one has a 57 date code




A Shout out to whoever reworked the GA _ 40 schematic and layout in the schematic library made getting a condenser list easy. I am tempted to power it up with a current limiter on one hand and shot gunning them all on the other, they all look OK but are either electrolytic or waxed. Your Thoughts   it looks like someone was in their a long long time ago . I can't be sure butat bare minimum the hard-wired tremolo is not present   and a couple wire connections look suspect. I'm really looking forward to the 6v6 tremolo for sure.

[PRR]

... leave my old amps tattered, waiting for the relic amp craze that's bound to happen some day

Won't happen until you make your amps nice. Or sell them for a pittance.

I remember the pink 1957 Plymouth that dropped reverse. We pushed it backward out in the street so Dad could go leave it at the Ford dealer and sign for a new 1966 Galaxie. Maybe they gave him $50? Recently I have seen similar Plymouths auction at $50,000.

[rafe]

Nice!!! I have a 1953 GA-40. Had a tough time getting the trem working - its a strange one. A couple of folks here helped me with it - there is a thread.
And man I want one of those GA-50s - Coolest cabinet ever!

From what I have heard The GA_50's and 50t's are to jazz guitarists as the Kalamazoo 2 is to harpers? Maybe fender should open up an amp relicing service and get the ball rolling

[bmccowan]

The cabinet covering is in better shape than mine. The guts about the same. I have worked on a lot of Gibsons from that era, and you will need to replace those electrolytic filter caps for sure. They weren't very robust and they are sitting in a hot environment. F&T brand is good and will fit in the same spaces. These point to point amps can be quite confusing so I go slow. The waxy paper tone caps are likely bad too. The white caps in the pic are newer - might be ok, might not. About half of the resistors in mine were way off spec.
 

[rafe]

"The waxy paper tone caps are likely bad too. The white caps in the pic are newer - might be ok, might not. About half of the resistors in mine were way off spec."




The PO has been in possession of these amps for 30 years and says He never plugged them in, previous to that His uncle had them since new (He thinks) I think I'll replace all 20 well not the death cap if it has it. I suspect a transformer may be a replacement. I'll check further today (The Numbers) if so, it was done early on. bmccowan, does yours have a triad brand output (I think) transformer? I'll post a photo later, Triads are pretty good, so I am not too concerned. P.S. As per first post I was able to walk the price back a little might cover the cost of most (some) of the caps for the GA-40

[TitaniumValhalla]

That thing needs some love for sure. I had a GA-20, 1952 or 1953 if I recall correctly that was in better cosmetic shape than that but I found that most of the resistors had drifted or were noisy, and all the caps were leaky. I sprang for fancy Jupiter coupling caps from Doug's store, replaced all the carbon comps with new, new F&T electrolytics, shotgun replaced it all and the amp sounded and performed beautifully when I was done. I sold it to fund something else like an idiot. These amps combined with an LP Gold Top are pretty much unbeatable guitar heaven.

A few pics...
https://i.ibb.co/VNNBv5C/cwdetna80sqexalcfgpb.jpg
https://i.ibb.co/NsL0WK0/f3exkhwwbusck70olioj.jpg
https://i.ibb.co/kQBZz17/fob5b6nqfykawgytsful.webp
https://i.ibb.co/qywLF6V/pvgsoqfojgwhvj00yw5i.jpg

[bmccowan]

Rafe - I'll take a look - but OTs are pretty robust, rarely fail.
But - and I mean no offence at all. My number one suggestion is that you do a bunch of reading before you dive into this amp. Both for the safety of the amp and you. It seems you need to come up to speed on some things.
Good place to start is right here with Doug's library of information.
Also - Rob Robinette's site. And Randall Aiken's site.
And, after you do that - try to change one thing at a time and test. The forum is full of projects where people did numerous repairs and/or mods at the same time without testing. Then they go on fishing expeditions. Its no fun.
I'll get back with that OT info and maybe a pic or two of my amp.

[rafe]

Fear not I'm pretty good at things I do. I'm not easily offended it's all good and not my first rodeo. You are right about OT's They rarely fail ,but fail they do. on closer inspection, the evidence points to a replacement. Panhead screws, not nuts& bolts and too long.  Point of screw threatening a wire. The heavy green plastic wire coming off it just didn't look right.  And I would expect a GA code on it. Plus, some obvious splices. They look professional but splices, nonetheless. The first point 2 point I did was an amp from the 30's it was a rat's nest but with the help and advice on this forum I managed. That was a challenge and probably still somewhere here in the archives.

[rafe]

Great pictures of the GA-20 by the way great amp and great band too. But why would someone put a domino in it??? 

[bmccowan]

Rafe - All good, I likely misinterpreted "output (I think) transformer?" The OT in mine looks very similar to yours, but not identical. The markings are worn off.
Nice job on your amp Titan... I like how you reused the lacquered spaghetti sleeves. I try to do that too, but sometimes they are just too burned from previous repairs. I like all the Gibsons from this era. But you are right that the caps and resistors did not hold up well - but damn, 1953 was the year I was born. Bit of wear and tear on me too.

[rafe]

I pulled the speaker, and the surround is detached (But cleanly) the cone is good; I am going to save it. Nothing to lose by trying. It's a P12Q 37th week of 52. if it doesn't I'll have it reconed. Hey 53 was a great year Corvettes came out. You came out and Me Too lol. Maybe the best year ever;lol

[Rontone]

I have read before about speakers sagging over time with gravity, that the suspension can start to sag and can make it rub and scratch, does this happen noticeably?

I've never really had my hands on many really old speakers, tried some old 50's hifi speakers before, but only have 80's and reissue type speakers like vintage 30's myself, have you ever spun a cone 180 degrees and it got better?

[rafe]

have you ever spun a cone 180 degrees and it got better?


I have never done that,  just dust covers and rips. I started on the surround, and it is going to be tedious and may not hold, I think I will move this one over to speakers now and start with pictures of it right after the start. It's going to take patience

[thetragichero]

as long as you keep the cone centered changing the surround successfully can be accomplished pretty easily. every 12" pyle driver i've pulled from lowery organs had rotted surrounds so i've done quite a few with rubber or the surround from paper/hemp cones (hemp-o speakers sent me a bunch of different options). i have not been successful with full recones as of yet

[rafe]

Glued up the pre-tolex covering on the GA-50T and got some Tan and some brown KIWI and gave it a wax and polish. Big strip missing on the left and too bad but OK. I started on a cap safari, for the Les Paul and it appears as if I'll have to work the cap cans under the hood and just disconnect them. A 10 10 450v and a 20 10 450v (500, 600) but I'm not seeing any. I'll keep looking though ......
"update" this one(50T) is a 1950 it appears!

[sluckey]

Could you use a single can (20/10/10/10)?

     https://www.tubesandmore.com/products/capacitor-ce-mfg-450v-20101010-f

[bmccowan]

Very cool - you can probably find a close match from an upholstery supply. But I would leave it just as it is. Hell it was well used, just not all that well cared for - same as most old amps.
Caps for the GA-40. I did what you are suggesting. I disconnected the cap cans and left them in place. I then used a dual 16uf F&T https://www.tubesandmore.com/products/capacitor-ft-500v-1616-f-axial-lead-electrolyticfor the 10/10 (Doug doesn't carry the dual axial F&Ts) and Single F&T 20 & 16 for the other two. I would not hesitate to use another 16/16 for that can, or even the 32/32. Others may argue, but I do not think it important to match the exact capacitance values, as long as you don't go too far astray. 10uf was considered pretty large in those days. I have an old amp that has 2uf filter caps!

[bmccowan]

Could you use a single can (20/10/10/10)?

That's a good idea too, and I considered it for mine. But the amp has those skinny cans and it would have required making the hole larger, which I decided not to do.

[bmccowan]

BTW did you find Jack Hester's drawings for the early GA-40? There is both a schematic and a layout. They are totally accurate as far as I determined. You need to zoom in to see what is there. I think he was a regular here before he sadly left us.

[rafe]

Yup, skinny cans, don't want to enlarge (change) chassis. I tucked the caps on the thunderbolt for the same reason (One skinny can) Didn't want to alter the chassis. I also like to keep the wires on short runs when possible. Plus, I like the look of the original. I usually don't like to go lower on the cap values (thanks for the insight bmc) looks like a little wouldn't hurt, but I prefer to go a little larger when necessary. The bottom of the amp on the 50t is missing it's covering,(BUT) there is a long 2' strip left under the chassis that I may or may not use on the front corner from the piping to, out of view from the front, it won't be invisible but if I overlap and cut, it would be very good, I'll ponder that for many moons. I found a great early schematic and layout on the les Paul.Gibson_ga_40_54_early.pdf (el34world.com) Is  this Jack Hester's work ? If so a shout out and thank you to Jack. He's still giving back! I don't know what made me think to try tan and brown Wax shoe polish on these two amps but man it worked beyond my expectations. The front of the Ga-40 is even more presentable than it was, and it wasn't bad, Thanks.

[rafe]

I ordered 2 16/16 f&T 500v I'm convinced it will be fine. 8 electrlytics, I got the non electrolytics in orange drops

[bmccowan]

Yes that is Jack's work. I found it a great help when working on mine.

[rafe]

I posted earlier about using "KIWI) shoe polish (Tan and Brown) It worked excellent EXCEPT where I got a little brown on the brass, just a tiny bit permeated the brass and when I tried to remove it, it spread a lot. I tried to sand a spot and it's deep and didn't improve it. So, I want to warn everyone about the danger .....The rest came out awesome and the tan seems neutral. I am bummed, but will continue to look for a solution. Any Suggestions

[sluckey]

Yup, skinny cans, don't want to enlarge (change) chassis.

I ordered 2 16/16 f&T 500v I'm convinced it will be fine.

You'll have to enlarge the hole to properly mount those F&T cans.

[sluckey]

Mineral spirits will likely remove the shoe polish from the brass.

[bmccowan]

You'll have to enlarge the hole to properly mount those F&T cans.

If he's getting the ones I linked to, they are not cans, they are axial dual capacitors. I've been using them for a while, really handy when space is an issue.

[sluckey]

Ah, didn't realize they made a dual axial. Sorry.

[rafe]

bmccowan saved me a post with that reply, I will try the mineral spirits, butit seemed more like a chemical reaction ???I I picked up what looks like a decent isolation transformer today for $10 I'll post it over on tools.

[bmccowan]

I wish Doug carried those dual axials. And I wish someone made skinny cap cans.
Shoe polish - I haven't polished a shoe in about 39 years (my wedding) but I was curious what is in that stuff. turns out it is Naptha & wax. So the Naptha likely reacted with the metal. That rules out what I was going to suggest; Naptha. I think I'd just leave it and make up a George Santos story. We were gigging a the Whiskey a Go-Go man, and this dude threw some stuff at us. I figured it was Whiskey but it ended up staining the amp man. Bummer.

[PRR]

> the Naptha likely reacted with the metal.

No way. Gasoline won't rot a steel tank, else we'd all be in trouble.

The brass was lacquered. Naptha will eat lacquer in a jiffy. Now the brass tarnishes.

Take ALL the lacquer off. Polish with rouge on a wheel or toothpaste on a rag (Flitz is great if you have it). Apply a good lacquer. Obviously now you wish you had removed the badge before staining, because it's gotta come off to be stripped and polished.

[rafe]

"Obviously now you wish you had removed the badge before staining, because it's gotta come off to be stripped and polished."


You bet, the sad part is that I didn't even need to get clost to that badge. The rag just brushed across it. I think a little heat would remove it(soften the glue) its loose in some areas already. I sure hope it works .....It looked so good.

[bmccowan]

else we'd all be in trouble

Aren't we?
+1 on the Flitz

[rafe]

caps and glue came in today. 24hr cure time on the glue, I'll test the speaker with a GA-5 tomorrow. The glue appears to be contact cement with a black dye in it. I got it from a speaker repair company. Paid for knowledge and got a 2oz sample! When I looked at the shipping list on the caps I was alarmed because I need 20 but they only shipped 18 .....I was careful with the order, so I know I needed 20. It didn't take but a few minutes to figure it out, so I saved myself the embarrassment of a phone call. I built an adjustable chassis cradle yesterday, very simple and very adjustable good angle doesn't roll around, but I can flip the chassis easy enough. I used to just block them up, but this is better. I can clam it or screw it down and flip them inward for small amps. Occam's razor ?

[rafe]

I am going to check the resistors as I go BMcC what did you use in yours? it calls for 1 and 1/2 watts I think they are mostly carbon comp? Recommendations??

[bmccowan]

Resistors - Yup, in those days they used carbon comp for just about everything except higher wattage ratings, like the power tube cathode resistors.
For mine and my other amps, I use 1/2 watt metal film for most. 1 watt carbon film is good too, but where the schematic shows 1 watt, I just jump up to 2 or 3 watt resisters. I do not use either carbon comps (noisy) or 1/2 watt carbon film (others here have reported failures with them.) I use 2w and 3w wire wounds for dropping resisters. Doug has all of these. I don't like the looks of 5 and 10 watt white cement body resistors, so I scrounge up older 5,10,20w resisters that look better to me (foolish, I know).

[rafe]

" so I scrounge up older 5,10,20w resisters that look better to me (foolish, I know)." 


I grabbed a box ful of old resistors lots of wire wounds higher wattage and small round, high precisions ....Those are spot on. the GA-40t has one 150 ohm 10 watt. I haven't checked it but it is likely good. I'm leaning towards ordering all new (except the 10 watt)