Bassman head circuit identification
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Bassman head circuit identification
Hi guys,
I've recently acquired a Fender Bassman head, but the sticker inside the chassis has taken quite a beating (and even so, i've seen multiple sources mention that they are sometimes inaccurate)
I want to identify which circuit I have, and was wondering what the key things I should look for are?
Things of note: The tolex is black, knobs are not original (chicken heads), there are 6 tubes total (so I guess this isn't a tube-rectified model?), there is a presence control on the front panel.
It hasn't been recapped (so I guess that's the first thing I should be looking to do... Would the caps be useful for identification purposes, or are they always the same?)
Based on what I have read online, I may have a 6G6-B, but i'm really no expert.
Also, what kind of speaker setup would you suggest? Currently on the lookout for a cab for this bad boy
Thanks!
I've recently acquired a Fender Bassman head, but the sticker inside the chassis has taken quite a beating (and even so, i've seen multiple sources mention that they are sometimes inaccurate)
I want to identify which circuit I have, and was wondering what the key things I should look for are?
Things of note: The tolex is black, knobs are not original (chicken heads), there are 6 tubes total (so I guess this isn't a tube-rectified model?), there is a presence control on the front panel.
It hasn't been recapped (so I guess that's the first thing I should be looking to do... Would the caps be useful for identification purposes, or are they always the same?)
Based on what I have read online, I may have a 6G6-B, but i'm really no expert.
Also, what kind of speaker setup would you suggest? Currently on the lookout for a cab for this bad boy
Thanks!
Re: Bassman head circuit identification
Need pictures and serial numbers.
Last edited by tubeswell on Sun Apr 30, 2017 8:19 pm, edited 1 time in total.
He who dies with the most tubes... wins
- martin manning
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Re: Bassman head circuit identification
6G6-A and -B are blonde, but there are exceptions. See here: http://www.thevintagesound.com/ffg/
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Re: Bassman head circuit identification
I will try to post pictures when I can open it up again.
Is there anything in particular I should be photographing that is a "dead giveaway"?
Also, for a speaker cab -- would a 1x12 cab with a Tone Tubby Alnico Red 50w 8 ohm speaker stand up to the abuse of the bassman? (Assuming its volume will likely never go higher than 7-8)
Thanks!
Is there anything in particular I should be photographing that is a "dead giveaway"?
Also, for a speaker cab -- would a 1x12 cab with a Tone Tubby Alnico Red 50w 8 ohm speaker stand up to the abuse of the bassman? (Assuming its volume will likely never go higher than 7-8)
Thanks!
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Re: Bassman head circuit identification
Also Martin, I looked on the site you provided -- the front panel layout of my amp is similar to the blonde ones (there are no deep or bright switches), even though the tolex is black...
It seems to fall into the exceptions on the 6G6-A Blonde bassman page.
Now... The amp powers up fine, I cleaned the pots with contact cleaner as they were all scratchy. Now, on the Normal side, the treble control brings in a bit of a hum (maximum treble = maximum hum, no treble = no hum), and the bass side inputs seem to not work at all.
Is it possible that i'm just not driving the bass side hard enough? (Currently running through an 8 ohm speaker that is wayyyy overbuilt for this amp -- an EVM12L)
The clean side sounds very nice with my strat, but i'd love to get this amp working as it should (pretty sure it's going to need to be re-capped as one of the big ones leaked slightly)
So much to think about..!
It seems to fall into the exceptions on the 6G6-A Blonde bassman page.
Now... The amp powers up fine, I cleaned the pots with contact cleaner as they were all scratchy. Now, on the Normal side, the treble control brings in a bit of a hum (maximum treble = maximum hum, no treble = no hum), and the bass side inputs seem to not work at all.
Is it possible that i'm just not driving the bass side hard enough? (Currently running through an 8 ohm speaker that is wayyyy overbuilt for this amp -- an EVM12L)
The clean side sounds very nice with my strat, but i'd love to get this amp working as it should (pretty sure it's going to need to be re-capped as one of the big ones leaked slightly)
So much to think about..!
- martin manning
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Re: Bassman head circuit identification
Could be one of those exceptions! 6G6-A and -B do not have a bias pot. AB165 has a bias balance pot with a center tap, while AA864 has a normal bias pot. Get some model numbers and date codes from the transformers.
Yes, re-cap for sure. Could be a number of things on the non-working channel. Are you going to work on it yourself?
Yes, re-cap for sure. Could be a number of things on the non-working channel. Are you going to work on it yourself?
Re: Bassman head circuit identification
Sounds like a tuxedo blonde Bassman
TM
TM
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Re: Bassman head circuit identification
I definitely want to start learning about tube amps and working on them. First thing that I want to do is build a stand so I can sit the chassis in it upside down so that I can properly prod around.
Next time I open it up I will check what the bias setup is and report back
I'm stoked if it really is one of the blondes, those circuits seem to be some of the more sought-after ones!
Next time I open it up I will check what the bias setup is and report back
I'm stoked if it really is one of the blondes, those circuits seem to be some of the more sought-after ones!
Re: Bassman head circuit identification
The fact that it has a black tolex and black faceplate with a presence knob leads to a 6g6b. BTW the tuxedo reference is the transitional model that has the later blond circuit with black tolex, faceplate, handle and white knobs.tremblaylive wrote: ↑Mon May 01, 2017 12:52 am I definitely want to start learning about tube amps and working on them. First thing that I want to do is build a stand so I can sit the chassis in it upside down so that I can properly prod around.
Next time I open it up I will check what the bias setup is and report back
I'm stoked if it really is one of the blondes, those circuits seem to be some of the more sought-after ones!
TM
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Re: Bassman head circuit identification
Thanks TM! Now to figure out which speakers to use with it (And fix the bass channel, so I can get some jumped goodness! )ToneMerc wrote: ↑Mon May 01, 2017 1:22 amThe fact that it has a black tolex and black faceplate with a presence knob leads to a 6g6b. BTW the tuxedo reference is the transitional model that has the later blond circuit with black tolex, faceplate, handle and white knobs.tremblaylive wrote: ↑Mon May 01, 2017 12:52 am I definitely want to start learning about tube amps and working on them. First thing that I want to do is build a stand so I can sit the chassis in it upside down so that I can properly prod around.
Next time I open it up I will check what the bias setup is and report back
I'm stoked if it really is one of the blondes, those circuits seem to be some of the more sought-after ones!
TM
Re: Bassman head circuit identification
I picked up a 6G6-A from local pawn shop for $325. and it has a loose black tolex put on it, blonde tolex is gone.
Based on serial number and tube chart it is a 1962 6G6-A and will get new blonde tolex and early grille cloth not the oxblood cloth.
Based on serial number and tube chart it is a 1962 6G6-A and will get new blonde tolex and early grille cloth not the oxblood cloth.
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Re: Bassman head circuit identification
* clip off or just lift one leg of the bypass cap on V2b's 100k plate resistor.tremblaylive wrote: ↑Mon May 01, 2017 12:07 pm
(And fix the bass channel, so I can get some jumped goodness! )
* change those .25 coupling caps to .022
* change 1M resistor to 33K to 56K.
* change .00025 to 330 to 390pf
TM
Last edited by ToneMerc on Mon May 01, 2017 2:39 pm, edited 1 time in total.
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Re: Bassman head circuit identification
No Bass channel function at all, Are all 4 small preamp tubes in the amp and there filaments lighted up?
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Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Re: Bassman head circuit identification
I wanna shop where you shop, this beat up one went for $1225 on fleabay , I almost pukedM Fowler wrote: ↑Mon May 01, 2017 1:36 pm I picked up a 6G6-A from local pawn shop for $325. and it has a loose black tolex put on it, blonde tolex is gone.
Based on serial number and tube chart it is a 1962 6G6-A and will get new blonde tolex and early grille cloth not the oxblood cloth.Fender Bassman 6G6a 01.jpg17240625_10208022267986087_8196783240664273999_o.jpgMarks 6g6a tube chart.jpg