6G6-B Bassman On The Bench

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Blackburn
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6G6-B Bassman On The Bench

Post by Blackburn »

Got this amp in for (MUCH NEEDED) repair from a bass player friend that owned a blues dive until a few years back. That place had been around since about '69, I think. I spent a good amount of time there, hanging with the house band, occasionally sitting in for a jam here and there and enjoying some good smoke in the back. Fond memories and a lot of very cool guys. :)

Anyway, someone seriously fucked this thing, and I'm amazed anyone would be so incredibly thoughtless. Here are some pics of it right after it was dropped off... Mind you, I didn't remove the cap pan. :shock:
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Blackburn
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Re: 6G6-B Bassman On The Bench

Post by Blackburn »

The cab was re tolexed at some point with something very UN-Fender, along with a silverface grill. Here's a shot of the eclectic selection of filter caps and a pro install of a 3 prong power cord. Oh, and there was tar applied for extra mojo! Lots of fun making these old parts pretty again. :x

I'm curious about the dropping string's first resistor after the choke. The schem shows a 4.7K and then a 27K. On this one, they're switched. Could this have been the dumbass that had his hands in here or do you think a Fender error. It's quite evident that he didn't care enough to properly install/remove components from the eyelets, so I'm pretty curious as to whether it came from Fender this way. Probably the moron, right? Any thoughts on the matter are welcomed.
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Blackburn
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Re: 6G6-B Bassman On The Bench

Post by Blackburn »

More pics....
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katopan
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Re: 6G6-B Bassman On The Bench

Post by katopan »

Wow. Seriously, exposed filter caps like that? Wow.

I was fortunate enough to borrow one of these off a friend a little while ago. Very nice sounding amps. In fact shortly after I started building one, but haven't finished it yet.

4K7 and 22K certainly sounds like a stuff up. They were as per the schematic in the one I had. Only deviation from the schematic in the power section was the first filter cap was made up of to 70uF in series instead of 20uF in parallel. Other than that a bias pot had been installed, 1K5 grid stoppers added to the power valves, a couple of changes to the tonestack and mixing resistors on the bass channel side, and a 12AT7 installed in the PI to make the gain levels of the normal channel very much like a Blackface.

Very nice amps if they're working well.
Teleguy61
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Re: 6G6-B Bassman On The Bench

Post by Teleguy61 »

Poor baby. Hate to see these amps abused.
Just built a 6G6B out of parts bin stuff, normal channel only, and it's a real nice amp.
Tone stack makes it not quite BF sounding, but still very punchy with the diode rectifier.
Nice.
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rp
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Re: 6G6-B Bassman On The Bench

Post by rp »

What matters is all there, won't take much to make it right then it'll be a real nice amp. I'd redo the cab too, heads are easy, back to blond. Then ready for an other 50 years of dive bar blues.

Show us picts when it's all prettied up.
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Re: 6G6-B Bassman On The Bench

Post by katopan »

If the faceplate is black (it looks so in the pics) then the original tolex would've been black rather than blonde. One of the '64 transition "Tuxedo" models.
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rp
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Re: 6G6-B Bassman On The Bench

Post by rp »

Thought I'd seen black faceplates with blonde tolex but it was long ago that I was around such things. But black w/ white knobs would be very nice too - along w/ a matching 6G15!
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ToneMerc
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Re: 6G6-B Bassman On The Bench

Post by ToneMerc »

katopan wrote:If the faceplate is black (it looks so in the pics) then the original tolex would've been black rather than blonde. One of the '64 transition "Tuxedo" models.
Correct, the tuxedo Blonde Bassman's are a rarity too.

TM
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Blackburn
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Re: 6G6-B Bassman On The Bench

Post by Blackburn »

Kato, thanks for the tip on the dropping string! I'll make the appropriate change.

RP, I would love to do everything for this thing, but I don't think he's itching to pay more than what's absolutely necessary to get her up and running again. This is already adding up to a bit of scratch for parts needed and labor.

The PI 12AX7 measured very poorly on my tester, so that one's gotta go. The others are alright as far as I could see. Hearing is better, though. In the pics you can see a 6PS .1uf as the entrance cap to the PI. Not sure what that was about, but I hated the way it was installed and took it out. I put in a 470pf ceramic. The schem shows a 500pf. Swapped all the bypass caps as a courtesy. I couldn't look at them the way they were before. New 3 prong power cord, rectifiers, cleaned up some of the mess and fixed that severed lead on the .047uf cap of the Normal channel's tonestack. On order are some F&Ts and a couple of other little bits, including cleaner for the pots. Things are looking good so far. :)

Here are more pics....
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Blackburn
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Re: 6G6-B Bassman On The Bench

Post by Blackburn »

All that I pulled...
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Blackburn
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Re: 6G6-B Bassman On The Bench

Post by Blackburn »

I got the itch to try and play this thing with parts on hand and went through three fuses. After some snooping, I discovered this wire tied to the + of the reservoir caps. :idea:
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rp
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Re: 6G6-B Bassman On The Bench

Post by rp »

Looks like you'll need to print out the schematic and go through and check off every single connection on this one. At least it's a cool amp to work on.
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Re: 6G6-B Bassman On The Bench

Post by pdf64 »

I got the itch to try and play this thing with parts on hand and went through three fuses. After some snooping, I discovered this wire tied to the + of the reservoir caps.
It's a good idea to use a light bulb limiter in these scenarios.
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Re: 6G6-B Bassman On The Bench

Post by katopan »

Yeah, every time you blow the fuse you have stressed the PT that bit more and stepped it closer to a future failure.
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