Bare Knuckle Pickups Forum
Forum Ringside => Guitars, Amps and Effects => Topic started by: Tinus on March 14, 2006, 12:56:33 AM
-
Hey there,
In just a few days I'll pick up a '58 Gibson GA-40 Les Paul amp which I'll swap/exchange with the owner for the Rickenbacker 330-12 I am selling. It's completely original (incl original Jensen P12 alnico 5, dust cover and wooden footswitch) and allegedly in good shape overall and fully functional. I can hardly wait to plug in my Casino and go for it :P .
These are fun amps with serious gig potential, at least for my playing style. It has a 14-16W poweramp (2x6V6) with a 12AX7 phase splitter and a 5Y3 rectifier and oddball valves for the preamp (5879's anyone?) and tremolo (6SQ7). Twin channel / Four inputs, master tone, one volume per channel and rate&depth for the tremolo. Luckily the oddball valves are in stock with Watford Valves and other dealers. Allegedly these amps sound darker than comparable Fenders of the era (Tweed Princetons, Deluxes) with a very warm compressed overdrive with great mid detail from volume 4 and up.
My plan with this amp is to have it checked by a friend who is an amp-tech (48 year old filter caps might not withstand regular playing very long).I'll also get replacement NOS valves. If I decide to gig it regularly I will get a modern replacement speaker as I wouldn't want to mess up the original Jensen. Ultimately I plan to study some and invest in proper tooling so I can service this amp myself. Then my next step would be to build a replica from scratch.
I'll keep y`all posted on this, while I wait inpatiently 'till Sunday. If it's any good in this current state I'll see if I can record a sound clip with my BKP90 equipped Casino.
-
Cool! I'll be interested to hear how it sounds. :)
-
I know that Tube Amp Doctor sells unusual valves, so check out their site.
-
Thx Tewboss, I already did that but they don't seem to stock them all. Might still drop them a line to ask them 'though.
-
That looks cool, looks like its had some usage which looks great :D Hopefully it sounds great aswell.
-
That looks cool, looks like its had some usage which looks great :D Hopefully it sounds great aswell.
Well I hope I look this good when I'm 48 years old :wink: Actually I think the tolex and tweed are in quite good nick and original speaker and components is rare. I saw a lot of Gibson amps of this age offered that were in hellish shape or badly restored, most with replacement speakers and issues like malfunctions in tremolo etc. So I'm very VERY curious as to how it'll sound :D
-
I heard someone playing a GA-15 at the Matamp factory and it made his Tele sound like a big ES-345 or something. He was so darn good though some of the sound would have been in his fingers, but still - instant classic warm jazz sound :D
He was running it at quite low levels so I never heard anything close to overdrive; from the clean sound I got the feeling it would've been great though.
-
That's a classy looking amp, I bet it'll be awesome.
-
Ditto Phil's comments above.
-
That's a classy looking amp, I bet it'll be awesome.
Well I sure hope so! Off course with an amp of this age all sorts of things could have gone wrong, like faulty valves, leaking capacitors, speaker and tranny failure etc. However because it's in working order I should be able to assess what it's capable of. According to the seller (who claims to be the second owner) the 1st owner only used it at very low levels in a Hawaii orchestra which is why it's in good shape both technically as in appearance.
For you trainspotters out there: George Harrison used this one for the Cavern gigs and the first album before going VOX. Just one more reason to get a nice Gretsch Duo Jet later to go with this amp :D. Also I think I saw one on stage with Johnny Cash in the Walk the Line movie, but that might well have been a similar Two-Tone Gibson amp of the era.
All I can say for now: waiting s%@cks, I literally have trouble sleeping because I'm so anxious to hear it :guitar4:
-
Well I got my amp, and although it needs some work it sure sounds excellent. It has a very deep and warm tone without being dull. The onset of overdrive is very gradual, at first the sound only thickens up before breaking. It sounds best with my Riviera and booster pedal (Banzai new Rising Sun II) adding some grit if I need it. Can't post any clips yet (sold my PXR-4) but I will record some in the following weeks when I can lay my hands om some adequate gear.
One interesting note is that my amp is not a GA40 but a GA20T (also from 1958). The only difference between the two is that the GA20T has a 12AY7 for the (lower gain) instrument input, while the GA40 has a 5879.
-
Some pictures:
-
And some more:
-
The main problem now is hum. My guess is the filter caps are deteriorated after almost 50 years. Some caps look like they've leaked wax so they are probably almost done. Luckily I met an amp tech while I was travelling with my amp and he agreed to have a look at it with me present, so that should be a nice field day.
-
I've always been tempted to splash out on a vintage amp myself, these pictures are bad for one's GAS don't ya know old boy.
-
looks blooming nice!!!!
-
I've always been tempted to splash out on a vintage amp myself, these pictures are bad for one's GAS don't ya know old boy.
Sure I do, I just like teasing :orcass:
Buying these things is quite a leap in the dark 'though, I found it hard assessing this amp at the seller's house because he hadn't run it in 5years or so and it needed some time to wake up again. However I'm glad I did, even now the sound is already way better than most current production amps of similar wattage and price (apart from some boutique combos maybe).
The reason I picked up up this one is that I like the power (14W) and speaker (Jensen P12R alnico) which makes for a nice home/recording/small stage amp. Also these were well built, better than most competitors and on par with it's direct competitor from Fender (Tweed Deluxe). The tweed Fenders of the same era have rather insane vintage value these days.
-
my fingers are tired... i cant be bothered to check if you already said the price on the last page... how much you pay for it?
-
Straight swap for my mid nineties Rickenbacker 330-12, so about €1000 in real life. That's not especially cheap if you compare it to prices in the USA but shipping, taxes and customs add a lot apart from the risk of damage. Also, this one hasn't been messed up by previous owners and still has it's orignal speaker in good shape so that adds a bit to the cost too.
-
cool thats a fair deal i spose, although i dont know much about the value of either items really.
-
The onset of overdrive is very gradual, at first the sound only thickens up before breaking.
So you mean there's a point where you can't tell whether it's clean or just really smoothly overdriven? That's the Holy Grail!!
I wonder if that characteristic has anything to do with the teeny transformer PDT_049
-
can't wait to hear a clip of your new acquisition.
I love small amps, though in my case even 15 watts is too much :(
Rob...
-
The onset of overdrive is very gradual, at first the sound only thickens up before breaking.
So you mean there's a point where you can't tell whether it's clean or just really smoothly overdriven? That's the Holy Grail!!
I wonder if that characteristic has anything to do with the teeny transformer PDT_049
That, and the lazy 5Y3 rectifier, the small power section, low power Jensen (rated only 12W), low preamp gain / no master volume, and ..... ow shoot, the whole thing combined I guess :D
-
can't wait to hear a clip of your new acquisition.
I love small amps, though in my case even 15 watts is too much :(
Rob...
In one week I'm gonna rehearse it (small band setup w/o drums) and I'll have access to a PXR-4 minirecorder so I'll try and record some then.
I doubt if this one would be too loud for you. It saturates pretty early (around 4) and only gets really loud past 8 or so. However it sounds thicker and larger than any amp of this size I ever heard and it's not even repaired yet :D.
-
I know that Tube Amp Doctor sells unusual valves, so check out their site.
FYI I checked their site again and found out they Do actually carry 6SQ7's and 5879's so I could use them to order valves too. I forgot to check the odd-ball tube section, silly me.... :oops:
-
In the mean time I sent some pics of the inside to a tech and made an appointment for a cap job and general maintenance for april 9th. I'll be present to watch and learn and will take some pics. I'll keep you all posted on the resurrection of this nice little ampie.
-
Well, the GA20 was serviced and restored today with excellent results. I had an excellent day because I got to watch every move and do some small chores to keep the process going.
Some basic stuff was done first. The awkward thin power cord was replaced with a modern one and the chassis is now connected to earth. I got a new external 220-110V transformer that could power three of these amps on full tilt so it's running nice and cool. The inside of the back panel was covered with metal foil for screening, which helped to reduce noise. The valve sockets were cleaned. Some were filled with an earwax-like substance that had leak out of the busted main filter caps.
The tech then measured almost every seperate part to assess if it still performed somewhere near the specs as in the circuit drawing. Apart from replacing the main filter caps all other electrolytic caps were replaced too, as well as some carbon resistors that had drifted too much. Funnily enough it turned out that there was a dead resistor just in front of the driver valve so the amp was running only at half power all the time 8) For nostalgic reasons we cleaned up and refitted a strange sand resistor in the power stage that is common to Gibson amps. (I first thought it was rotting or something but I found out they were supposed to look like that). We left the tremolo alone for now. It doesn't work properly yet but repacing the 6SQ7 might fix it so I'll try that sometime soon.
I'm not gonna ramble alot about the sound but boy.... The nasty noise and hum is gone, the amp is literally twice as loud as before and it sounds much livelier. It will easily handle bar and medium sized venue gigs, it's incredibly loud for it's demure size. The single tone control works nicely. From very dark to normal on the first half of it's travel, from there the sound loosens up and the volume increases. With my BKP Casino and Banzai booster it's instant Neil Young now. Will try and post pics and a soundclip soon.