1965 Fender Bassman

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1965 Fender Bassman

Postby Kingdilph on Sun Jun 04, 2017 9:46 pm

Hey guys got a Bassman last year from an amp tech had some work done on it but noticed I have the turn the Treble up more than compared to a few months ago. Just curious could it be the tubes? Or something else i took it apart and took some pics a few weeks ago. Considering maybe getting 1 or 2 NOS tubes in V3 or V4 I only use the Normal Channel. I usually rock the bright switch on with the Treble on 6.5-5 and bass on 6-4 depending on the room.
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Re: 1965 Fender Bassman

Postby OldSchoolDave on Mon Jun 05, 2017 1:21 am

Kingdilph wrote:Hey guys got a Bassman last year from an amp tech had some work done on it but noticed I have the turn the Treble up more than compared to a few months ago. Just curious could it be the tubes? Or something else...


Not to be a smart @ss, but has your hearing changed recently? Any sinus infections or tinnitus?

Also not to be a smart @ss, but were your speakers new at the time and now broken in? It is typical for some high end to smooth off during the break-in process.

If all things are equal then, yes, experiment with some different tubes. That could well be the culprit.

Dave
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Re: 1965 Fender Bassman

Postby Kingdilph on Mon Jun 05, 2017 8:04 pm

OldSchoolDave wrote:
Kingdilph wrote:Hey guys got a Bassman last year from an amp tech had some work done on it but noticed I have the turn the Treble up more than compared to a few months ago. Just curious could it be the tubes? Or something else...


Not to be a smart @ss, but has your hearing changed recently? Any sinus infections or tinnitus?

Also not to be a smart @ss, but were your speakers new at the time and now broken in? It is typical for some high end to smooth off during the break-in process.

If all things are equal then, yes, experiment with some different tubes. That could well be the culprit.

Dave


Yeah haha I thought it might be my hearing. The speakers were new when I bought them a year ago probably could be partially that. Just something i noticed in the past 5 months. I'm running it with an open back 2x12 Avatar Cab with G12M65 Creambacks. It was bothering me so i took some pics of the inside will post in a bit. The treble pot is a bit crackly on the normal channel. I have high gain JJ ECC83's in there I've pulled out the V3 a few times because of thought it was going microphonic but noticed that any tube i put in there has a bit of a 'ping' sound with a tap it. Just hoping it’s nothing serious like a coupling cap nearing its end.
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Re: 1965 Fender Bassman

Postby OldSchoolDave on Mon Jun 05, 2017 11:50 pm

Kingdilph wrote:The treble pot is a bit crackly on the normal channel.


An oxidized Treble pot could cause a loss of high end. Exercise it and see if the response returns.

As to V3, do you need the drive of a high gain tube there or could you use something slightly tamer?

Dave
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Re: 1965 Fender Bassman

Postby Kingdilph on Wed Jun 07, 2017 2:14 am

OldSchoolDave wrote:
Kingdilph wrote:The treble pot is a bit crackly on the normal channel.


An oxidized Treble pot could cause a loss of high end. Exercise it and see if the response returns.

As to V3, do you need the drive of a high gain tube there or could you use something slightly tamer?

Dave


Here's the pics

https://imgur.com/a/dYGH4
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Re: 1965 Fender Bassman

Postby Kingdilph on Wed Jun 07, 2017 2:15 am

Was thinking about trying some NOS tubes in it maybe a Mullard PI or some lower gain tubes open to options really. I know the original circuit calls for 7025 tubes.
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Re: 1965 Fender Bassman

Postby Naked Clarke on Wed Jun 07, 2017 2:45 pm

Nice AA165 Bassman. There are many AA tube charts out there but this circuit in the Bassman was only produced during the first quarter of 1965.
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Re: 1965 Fender Bassman

Postby Kingdilph on Thu Jun 08, 2017 1:49 am

Naked Clarke wrote:Nice AA165 Bassman. There are many AA tube charts out there but this circuit in the Bassman was only produced during the first quarter of 1965.


Is it an aa165 thought it was an aa864 i guess they're kind of a similar circuit I think the date is Feb 1965
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Re: 1965 Fender Bassman

Postby Naked Clarke on Thu Jun 08, 2017 11:28 am

Kingdilph wrote:
Naked Clarke wrote:Nice AA165 Bassman. There are many AA tube charts out there but this circuit in the Bassman was only produced during the first quarter of 1965.
Is it an aa165 thought it was an aa864 i guess they're kind of a similar circuit I think the date is Feb 1965


Yours was wired up during the 4th week of January. Most of Production run #1 from this time are stamped OB. There are some Bassman amps with OA tube chart stamps out there but they are stamped with green ink and were factory mistakes from January 1966. Yours may well have an AA864 tube chart but it is the AA165 circuit. Serial number around A03900?
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Re: 1965 Fender Bassman

Postby Kingdilph on Tue Jun 13, 2017 2:15 am

https://www.youtube.com/watch?v=MmwR7M52cXQ


Here's a vid of it cranked was bored this weekend. Godspeed
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Re: 1965 Fender Bassman

Postby Dean Jr. on Wed Jun 21, 2017 7:36 pm

That amp appears to be an actual AA165.....they are rarely seen. There are many AB165 amps with AA165 tube charts, but there are not many true AA165's around.
As to the problem??? I start with this type of problem by tending to the simple stuff. I just cured a 1999 Fender Pro Sonic of weak high end by tightening the treble pot. Improper ground was preventing that circuit from working properly. After the simple things are dealt with, one then starts looking deeper into the circuit....bad cap??
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