Silverface Bassman Versions and Bassman Ten Cap Question (Pic Heavy)
Posted: Sun Jul 11, 2021 9:05 am
1) Restoring My Bassman Ten:
Hey, everyone. I’ll try to keep this kinda brief, but in trying to figure out some internal things about my 1974 Bassman Ten, I realized I had a lot of other confusion about SF Bassman amps and wondered if any experts here might advise on exactly what I've got going on with my workhorse.
So, I’ve never been an amp expert, that’s part of the reason I love my Bassman Ten. I’ve posted positively about it since I got it in 2008, and it’s worked reliably for years. Shortly after I got it, it turned out it needed some work. Two of the original speakers crapped out and I believe the filter caps and maybe some preamp tubes were on the list. I'm almost certain the filter caps were changed, but I'm not going in that doghouse. When I bought it, I had just moved to a new city and didn’t know where to take it, so took it some place at random I saw nearby. My instructions were basically "I don't need anything fancy or hot rodded, just please get it back to 'about stock'." Just a beat-up player/workhorse of an amp. Part of my problem is that I knew even less about amps back then than I do now. I honestly can't remember what was done to it, so I opened it up for a cleaning and to take a careful look inside and was a little surprised.
The underside of the chassis was gross. Had a sticky layer of dust and grime. I was worried it was from a smoking amp in the past, but it may have just been 45 years of smoky clubs. I scrubbed and wiped off as much as I could, carefully, got most of it, but now I'm a little paranoid about the cause. Of course, it could have been there since I bought it.
The power tubes were not 6L6s like I expected, but a mismatched pair of 5881's. One Made In Russia, one from the USSR. I've never changed them. I've never needed to. The amp has just WORKED. It ended up not being a gigging amp, but a living room one. Jams with friends, drug it to a dozen big loud rehearsals, maybe half a dozen gigs. I've never pushed the MV that hard (outside the gigs), and never noticed any tonal problems. I hear these make for lower clean headroom. The power tubes start to get a little growly at about 6.5+. Rarely have I had the need to get it up above that in bars and rehearsal rooms. But I had no idea. I've found myself largely unable to overdrive the front end unless I turn both channels to 10 and hit it with the hottest cheap humbuckers I've got, and that's how I like it. I'd love to maximize clean headroom on this thing for my pedalboard to paint on, so 6L6s and a biasing will be necessary, I just don't have the money at the moment.
The tube brackets don't grip the short ("wafer"?) bases of the tubes as well as I'd like. I occasionally reach back with a paper towel before I turn on the amp and make sure they're secure. Now I realize why. The brackets actually have a tendency to push the tubes out just a little, squeezing a bit against the curved glass bottle. I do not like this. I don't want arcing. I intend to remedy this as soon as I can afford some new tubes and a biasing at the local tech. Eventually.
BUT THE BIGGEST QUESTION: I took some pics. I watched some repair videos online of my model, the 50W, pre-UL version, and they consistently have a cap visible in the chassis -- that is straight up missing inside mine. [HIGHLIGHTED IN PICTURE BELOW]. Where I've seen that cap in other examples online, it's connected from the bias adjustment pot to (I believe) a ground spot on the chassis near the power cord input. I wish I'd noticed this when I had the thing apart to take better pictures, but can anyone let me know if this is something I should be seriously concerned about? Or if they see any other red flags?
I just wanna get this old beast back to tip-top. Pics:
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
External shots are PRE-cleaning, for what it's worth. It's looking better now.
2) Silverface Bassman Series Info
I love my amp, I do. It's always sounded good, nice 'n' full, takes pedals like a beast, jumpering the channels and setting everything to "7" is glorious. I'll re-iterate that I'm no amp expert, but it seems like there were a bunch of Bassman variants in the SF era, and I've always wondered how mine differed. I'm aware of:
Bassman Amp (Bassman 50) - 50W head, non-UL
Bassman 70 - 70w head, ultra linear
-----
Super Bassman I & II - piggyback head and cab combo, 100W
-----
Bassman 100 - piggyback or head, 100W, non-UL
Bassman 135 - ultralinear version of 100, now 135W
-----
Bassman Ten - 4x10 combo, 50w (til '77, then 70W)
-----
Bassman 20 - strange early-'80s combo, 18W
I realize that these aren't the same circuit as a tweed or BF. I don't want it to be. As far as my Bassman Ten is concerned, I believe it's got one less preamp tube per channel, so stays clean longer (pretty much to 10, with single coils). But is that the only difference in the circuit? Or were there other changes made in the Bassman Ten that push it further away from the (again, as I understand it), otherwise similar guts of a 50/100? I know there's a lot of specific circuit numbers throughout the years that people compare and discuss, but does the B10 have it's own circuit designation? Or is it simply the same circuit as the 50/100 with a preamp tube removed and a different transformer?
And real-world talk, not specs, how do any of you feel the ultralinear amps from '77 onward compare in feel and sound?
Thanks for the education, everyone. Y'all are real cool, and I love ya. Stay safe.
Hey, everyone. I’ll try to keep this kinda brief, but in trying to figure out some internal things about my 1974 Bassman Ten, I realized I had a lot of other confusion about SF Bassman amps and wondered if any experts here might advise on exactly what I've got going on with my workhorse.
So, I’ve never been an amp expert, that’s part of the reason I love my Bassman Ten. I’ve posted positively about it since I got it in 2008, and it’s worked reliably for years. Shortly after I got it, it turned out it needed some work. Two of the original speakers crapped out and I believe the filter caps and maybe some preamp tubes were on the list. I'm almost certain the filter caps were changed, but I'm not going in that doghouse. When I bought it, I had just moved to a new city and didn’t know where to take it, so took it some place at random I saw nearby. My instructions were basically "I don't need anything fancy or hot rodded, just please get it back to 'about stock'." Just a beat-up player/workhorse of an amp. Part of my problem is that I knew even less about amps back then than I do now. I honestly can't remember what was done to it, so I opened it up for a cleaning and to take a careful look inside and was a little surprised.
The underside of the chassis was gross. Had a sticky layer of dust and grime. I was worried it was from a smoking amp in the past, but it may have just been 45 years of smoky clubs. I scrubbed and wiped off as much as I could, carefully, got most of it, but now I'm a little paranoid about the cause. Of course, it could have been there since I bought it.
The power tubes were not 6L6s like I expected, but a mismatched pair of 5881's. One Made In Russia, one from the USSR. I've never changed them. I've never needed to. The amp has just WORKED. It ended up not being a gigging amp, but a living room one. Jams with friends, drug it to a dozen big loud rehearsals, maybe half a dozen gigs. I've never pushed the MV that hard (outside the gigs), and never noticed any tonal problems. I hear these make for lower clean headroom. The power tubes start to get a little growly at about 6.5+. Rarely have I had the need to get it up above that in bars and rehearsal rooms. But I had no idea. I've found myself largely unable to overdrive the front end unless I turn both channels to 10 and hit it with the hottest cheap humbuckers I've got, and that's how I like it. I'd love to maximize clean headroom on this thing for my pedalboard to paint on, so 6L6s and a biasing will be necessary, I just don't have the money at the moment.
The tube brackets don't grip the short ("wafer"?) bases of the tubes as well as I'd like. I occasionally reach back with a paper towel before I turn on the amp and make sure they're secure. Now I realize why. The brackets actually have a tendency to push the tubes out just a little, squeezing a bit against the curved glass bottle. I do not like this. I don't want arcing. I intend to remedy this as soon as I can afford some new tubes and a biasing at the local tech. Eventually.
BUT THE BIGGEST QUESTION: I took some pics. I watched some repair videos online of my model, the 50W, pre-UL version, and they consistently have a cap visible in the chassis -- that is straight up missing inside mine. [HIGHLIGHTED IN PICTURE BELOW]. Where I've seen that cap in other examples online, it's connected from the bias adjustment pot to (I believe) a ground spot on the chassis near the power cord input. I wish I'd noticed this when I had the thing apart to take better pictures, but can anyone let me know if this is something I should be seriously concerned about? Or if they see any other red flags?
I just wanna get this old beast back to tip-top. Pics:
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
upload image file
External shots are PRE-cleaning, for what it's worth. It's looking better now.
2) Silverface Bassman Series Info
I love my amp, I do. It's always sounded good, nice 'n' full, takes pedals like a beast, jumpering the channels and setting everything to "7" is glorious. I'll re-iterate that I'm no amp expert, but it seems like there were a bunch of Bassman variants in the SF era, and I've always wondered how mine differed. I'm aware of:
Bassman Amp (Bassman 50) - 50W head, non-UL
Bassman 70 - 70w head, ultra linear
-----
Super Bassman I & II - piggyback head and cab combo, 100W
-----
Bassman 100 - piggyback or head, 100W, non-UL
Bassman 135 - ultralinear version of 100, now 135W
-----
Bassman Ten - 4x10 combo, 50w (til '77, then 70W)
-----
Bassman 20 - strange early-'80s combo, 18W
I realize that these aren't the same circuit as a tweed or BF. I don't want it to be. As far as my Bassman Ten is concerned, I believe it's got one less preamp tube per channel, so stays clean longer (pretty much to 10, with single coils). But is that the only difference in the circuit? Or were there other changes made in the Bassman Ten that push it further away from the (again, as I understand it), otherwise similar guts of a 50/100? I know there's a lot of specific circuit numbers throughout the years that people compare and discuss, but does the B10 have it's own circuit designation? Or is it simply the same circuit as the 50/100 with a preamp tube removed and a different transformer?
And real-world talk, not specs, how do any of you feel the ultralinear amps from '77 onward compare in feel and sound?
Thanks for the education, everyone. Y'all are real cool, and I love ya. Stay safe.