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Finally found a Gibson GA 6 (with two 12AX7s) amp that I was able to give an offer for and pick up for under $800. Originally, I thought the coupling caps were not original, but it turns out that Gibson possibly used .047 Bumblebees when they switched from .05 Astrons to .047 caps. I found a post on a site that had a 1958 GA 6 with a manual and it included the schematic. These are essentially the same as a GA 20 minus the extra 12AX7 and lower wattage. They share the same PT and possibly the OT on certain years. Both models are comparable to Tweed Deluxes from the same era except that these are incredibly fatter. I love the wear on the tolex and it even smells of smoke. It has that "vibe" going for it. Pretty sure this was gigged heavily in its hay day.
Mine was listed as a 1956. With the cap change to bumblebees, it can be as late as 1958. Everything seems to be stock minus the original tubes, some wiring, resistors, and tube sockets. The back panel and Gibson logo are also missing. It had a paper cut out logo too. I believe the grill cloth is also not stock. She even has the GE lamp wire prong still hooked up.
Having owned an earlier version in the past, I know that the filter caps and cathode bias resistor (dog bone resistor) have to go. The pots are scratchy, so I'm hoping they can be cleaned. The amp is currently with my tech. He is applying the changes and looking through for other issues to give it a clean bill of health.
Before taking it there though, I went through the amp and cleaned it thoroughly. It had a tons of spider webs and what looked like dead spiders. There were old stock parts (resistors, wires, and etc) in the cabinet that I had to take out. The speaker that came with the amp wasn't stock. Afterwards, I began to disassemble the amp to clean the inside and peek at the irons. The PT is stamped "GA-20" and the OT has the same code that my previous amp had. The irons are original. After cleaning the inside with a vacuum attachment, I attempted to install the replacement speaker. A Celestion Alnico Blue.
After lurking on old threads from multiple forums, this is pretty much what most recommend in a Tweed Deluxe. I have to say the hype is real. Wow. Before, the amp had a pretty fat clean tone, but now it is a bit more balanced. The top end is now shimmery. My Koa 356 with Seth Lovers literally loves this amp with the Alnico Blue. A match made in heaven. I have yet had the courage to crank amp the up since I don't have a 3 prong wire. The clean tone is great however.
As I was installing the Alnico Blue, I ran into an issue. The bolts that hold the speaker in place were too long and it didn't provide enough clearance to drop in the speaker as is. I had to remove the baffle and install from the front.
With the baffle out of place, the speaker went on without a problem. I soldered the OT directly to the speakers, but will get a cable to hook up to my SPL power soak (live in a small studio). I then began to reassemble the amp and had her ready to take her to my tech. I think that I'm going to stick to the GE 12AX7As, but will be using Sylvannia 6v6GTYs. They have great clarity and just the right amount of gain. The bottom end holds strong too. I got a Bendix 6106 which is a heavy duty 5Y3. It should add some great detail and bite. Will be tube rolling with this amp. That's amount of for now. I have to look into the back panel material for the amp. I believe the can is made out of redwood. Not sure about the baffle. Mojotone sells their tweed panels made of baltic birch ply. I might just order a custom one to further protect the chassis. I think that's why it's looking a little rough and why the pots are so scratchy. Tons of dust/grime in there.
Fast forward 2 weeks. The amp is back from my tech. Turns out that 4 of the 5 bumblebees went bad. Two were leaking and the other two were noisy. Unfortunate, but given the amps age, it was expected at a certain point. The Astrons are good for now, they might go in the future. I went with Sozo Blue caps since they're suppose to be as good as The old yellow Astrons. They're cheaper than Jupiters too. The old filter caps were changed. Went with F&T and my tech bumped the 20uf up to 30uf (F&T w/a sprague atom). It tighten up the bass really well. The cathode bias resistor was changed and some other too. One of the GE tubes was weak, so I moved it to the PI slot. I put in a RCA 7025 in V1. The pots were cleaned and dated. A 3 prong cable was added. The amp is from 1957. Now that the amp has a clean bill of health, I finally cranked the mic channel. Wow. Lew was right. These things can sound like mini Marshalls. The Alnico Blue adds some of that Brit flavor. The amp is pretty loud too. Sounds great with a strat, LP, 335, or a 356. Very dynamic. It responds well to pick attack. Roll the volume down and you'll get a fat clean tone. I must prefer the two 12AX7 version over the 6SL7 in the earlier amps. I have an amp logo shipping soon. The rear baffle still needs to be ordered. Those will be the finishing touches, but I can crank her up and have a peace of mind \m/
Sent from my LG-H931 using Tapatalk
Mine was listed as a 1956. With the cap change to bumblebees, it can be as late as 1958. Everything seems to be stock minus the original tubes, some wiring, resistors, and tube sockets. The back panel and Gibson logo are also missing. It had a paper cut out logo too. I believe the grill cloth is also not stock. She even has the GE lamp wire prong still hooked up.
Having owned an earlier version in the past, I know that the filter caps and cathode bias resistor (dog bone resistor) have to go. The pots are scratchy, so I'm hoping they can be cleaned. The amp is currently with my tech. He is applying the changes and looking through for other issues to give it a clean bill of health.
Before taking it there though, I went through the amp and cleaned it thoroughly. It had a tons of spider webs and what looked like dead spiders. There were old stock parts (resistors, wires, and etc) in the cabinet that I had to take out. The speaker that came with the amp wasn't stock. Afterwards, I began to disassemble the amp to clean the inside and peek at the irons. The PT is stamped "GA-20" and the OT has the same code that my previous amp had. The irons are original. After cleaning the inside with a vacuum attachment, I attempted to install the replacement speaker. A Celestion Alnico Blue.
After lurking on old threads from multiple forums, this is pretty much what most recommend in a Tweed Deluxe. I have to say the hype is real. Wow. Before, the amp had a pretty fat clean tone, but now it is a bit more balanced. The top end is now shimmery. My Koa 356 with Seth Lovers literally loves this amp with the Alnico Blue. A match made in heaven. I have yet had the courage to crank amp the up since I don't have a 3 prong wire. The clean tone is great however.
As I was installing the Alnico Blue, I ran into an issue. The bolts that hold the speaker in place were too long and it didn't provide enough clearance to drop in the speaker as is. I had to remove the baffle and install from the front.
With the baffle out of place, the speaker went on without a problem. I soldered the OT directly to the speakers, but will get a cable to hook up to my SPL power soak (live in a small studio). I then began to reassemble the amp and had her ready to take her to my tech. I think that I'm going to stick to the GE 12AX7As, but will be using Sylvannia 6v6GTYs. They have great clarity and just the right amount of gain. The bottom end holds strong too. I got a Bendix 6106 which is a heavy duty 5Y3. It should add some great detail and bite. Will be tube rolling with this amp. That's amount of for now. I have to look into the back panel material for the amp. I believe the can is made out of redwood. Not sure about the baffle. Mojotone sells their tweed panels made of baltic birch ply. I might just order a custom one to further protect the chassis. I think that's why it's looking a little rough and why the pots are so scratchy. Tons of dust/grime in there.
Fast forward 2 weeks. The amp is back from my tech. Turns out that 4 of the 5 bumblebees went bad. Two were leaking and the other two were noisy. Unfortunate, but given the amps age, it was expected at a certain point. The Astrons are good for now, they might go in the future. I went with Sozo Blue caps since they're suppose to be as good as The old yellow Astrons. They're cheaper than Jupiters too. The old filter caps were changed. Went with F&T and my tech bumped the 20uf up to 30uf (F&T w/a sprague atom). It tighten up the bass really well. The cathode bias resistor was changed and some other too. One of the GE tubes was weak, so I moved it to the PI slot. I put in a RCA 7025 in V1. The pots were cleaned and dated. A 3 prong cable was added. The amp is from 1957. Now that the amp has a clean bill of health, I finally cranked the mic channel. Wow. Lew was right. These things can sound like mini Marshalls. The Alnico Blue adds some of that Brit flavor. The amp is pretty loud too. Sounds great with a strat, LP, 335, or a 356. Very dynamic. It responds well to pick attack. Roll the volume down and you'll get a fat clean tone. I must prefer the two 12AX7 version over the 6SL7 in the earlier amps. I have an amp logo shipping soon. The rear baffle still needs to be ordered. Those will be the finishing touches, but I can crank her up and have a peace of mind \m/
Sent from my LG-H931 using Tapatalk
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