Bassman ab165 to aa864?

Bikerider20

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Is it possible to modify a bassman a 1966 ab165 bassman to a aa864 circuit? Or can I do some mods to the ab165 bassman to make it sound better?
 

ReverendRevolver

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Is it possible to modify a bassman a 1966 ab165 bassman to a aa864 circuit? Or can I do some mods to the ab165 bassman to make it sound better?

AB165 sounds better than aa864. AA864 sounds like a gimped BF twin.

Have a tech go through the ab165 and troubleshoot.

What cab you running?
 

bebopbrain

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Yes, the AB165 can be configured as an AA864; this is not difficult. If this is a vintage amp, it may not be an ideal mod platform.

There are various differences in the circuits which give the AB165 more gain. The most significant differences might be:

1. The the AA864 has an unbypassed cathode. Maybe remove one capacitor from your AB165 (from the stage before the phase inverter).

2. The AA864 sums channels at the input to the phase inverter. The AB165 sums one stage earlier (the stage with the capacitor we just talked about). This means the AA864 normal channel has one entire gain stage less.

If that nasty gain is bothering you, go for it.
 

Bikerider20

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AB165 sounds better than aa864. AA864 sounds like a gimped BF twin.

Have a tech go through the ab165 and troubleshoot.

What cab you running?
I like the ab165 I just want it to be a little cleaner and I’m about to buy one and I don’t have a cab but me and my grandpa are gonna build a 2x12 and I’m thinking of putting swamp thangs or Weber ceramic Chicago’s
 

Bikerider20

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Yes, the AB165 can be configured as an AA864; this is not difficult. If this is a vintage amp, it may not be an ideal mod platform.

There are various differences in the circuits which give the AB165 more gain. The most significant differences might be:

1. The the AA864 has an unbypassed cathode. Maybe remove one capacitor from your AB165 (from the stage before the phase inverter).

2. The AA864 sums channels at the input to the phase inverter. The AB165 sums one stage earlier (the stage with the capacitor we just talked about). This means the AA864 normal channel has one entire gain stage less.

If that nasty gain is bothering you, go for it.
I don’t mind the gain just want it to happen at a little bit higher on the volume knob
 

ReverendRevolver

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It’s not mine…yet the owner is using green backs which isn’t good and the amp has never been serviced it probably needs a full run through

As Paul G says, and what I meant by having a tech troubleshoot, an AB165 is not normally one someone immediately hears and wants to mod, it most likely has some issues in there. It's pushing 60. When I'd bought mine, it'd had a new power cord and nothing else. The guy I sold it to had his tech look at it, and it was due for a recap. Mine was a '68 SF, and I'd sold it around 7 years ago.

Greenbacks are great for amps with lotsa mids and some highs, and typically come in a closed back enclosure to give more boom. A Friend of mine had left his 4×12 at my house for awhile (laid out in a column, he made a birch ply closed back cab and shaped a coffin shape around it out of cheaper ply...) it had 80s GBs in it. I liked the projection if it, as I had an early 70s fender bassman100 pyramid 4×12 at the time, but GBs didn't sound right like the beaten in fenders did.

Conversely, Mike Ness runs Billy Zoom modded AB165s into Marshall 4×12s, and it sounds fine with that mod.

Unless you're deliberately running inefficient speakers, you shouldn't get dirty gain until past 6 on the knob, and even then it wouldn't be much lower.
I reccomend taking it to a tech.

The AA864 isn't a bad amp, but they don't have as many good sounds inside as thier successor. When I bought my AB165 in 2005ish, the SF ones were ~$300, while BF cracked a grand. This was when everyone "knew" Silverface sucked and Blackface were better. I'd played a BF bassman first. Months later, I tried another, along with a few SF. I didn't understand it. I kept trying aa864s, hoping to "get it". I'll eventually buy another AB165. It's predecessor sounds very Fendery, but less good than the brown/blonde ones before it, and less versatile than the SF.

I advise a tech trip and playing some aa864 in person before doing any modding.

Building a cab with your grandfather will certainly give you an enclosure better than anything you can buy right now for the money. Does he play?
 

Bikerider20

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As Paul G says, and what I meant by having a tech troubleshoot, an AB165 is not normally one someone immediately hears and wants to mod, it most likely has some issues in there. It's pushing 60. When I'd bought mine, it'd had a new power cord and nothing else. The guy I sold it to had his tech look at it, and it was due for a recap. Mine was a '68 SF, and I'd sold it around 7 years ago.

Greenbacks are great for amps with lotsa mids and some highs, and typically come in a closed back enclosure to give more boom. A Friend of mine had left his 4×12 at my house for awhile (laid out in a column, he made a birch ply closed back cab and shaped a coffin shape around it out of cheaper ply...) it had 80s GBs in it. I liked the projection if it, as I had an early 70s fender bassman100 pyramid 4×12 at the time, but GBs didn't sound right like the beaten in fenders did.

Conversely, Mike Ness runs Billy Zoom modded AB165s into Marshall 4×12s, and it sounds fine with that mod.

Unless you're deliberately running inefficient speakers, you shouldn't get dirty gain until past 6 on the knob, and even then it wouldn't be much lower.
I reccomend taking it to a tech.

The AA864 isn't a bad amp, but they don't have as many good sounds inside as thier successor. When I bought my AB165 in 2005ish, the SF ones were ~$300, while BF cracked a grand. This was when everyone "knew" Silverface sucked and Blackface were better. I'd played a BF bassman first. Months later, I tried another, along with a few SF. I didn't understand it. I kept trying aa864s, hoping to "get it". I'll eventually buy another AB165. It's predecessor sounds very Fendery, but less good than the brown/blonde ones before it, and less versatile than the SF.

I advise a tech trip and playing some aa864 in person before doing any modding.

Building a cab with your grandfather will certainly give you an enclosure better than anything you can buy right now for the money. Does he play?
He used to play and he was in a band around the same age I was and he had a 50s telecaster and then he sold it for a 65 strat and then he sold that when he went into the service but he was a woodworker a long time ago and he’s still got it and it would be a good bonding experience
 

Wally

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He used to play and he was in a band around the same age I was and he had a 50s telecaster and then he sold it for a 65 strat and then he sold that when he went into the service but he was a woodworker a long time ago and he’s still got it and it would be a good bonding experience

BikeRider20, do I remember correctly that you are the member who has an incorrect age in your bio but cannot change it? Your story makes me think that you are quite a bit older than 19.
 

Bikerider20

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BikeRider20, do I remember correctly that you are the member who has an incorrect age in your bio but cannot change it? Your story makes me think that you are quite a bit older than 19.
oh lol I am 19 I just put 20 because it sounds better than 19 to me
 

Wally

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Okay….so your friend is much older than you but was in a band when he was the same age as you are now????
 

schmee

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Is it possible to modify a bassman a 1966 ab165 bassman to a aa864 circuit? Or can I do some mods to the ab165 bassman to make it sound better?
The AB165 is probably my least favorite Bassman. That may be just because when I use a Bassman, I want big clean power. The AB165 seems a bit more gritty to me. Now if I was trying to use it and tame the volume.... maybe that would be a good thing...? Sure the mod is do able. IIRC though it's not just a couple of little things. Fender went through some widely varied changes in the Bassman Head.
 

Bikerider20

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The AB165 is probably my least favorite Bassman. That may be just because when I use a Bassman, I want big clean power. The AB165 seems a bit more gritty to me. Now if I was trying to use it and tame the volume.... maybe that would be a good thing...? Sure the mod is do able. IIRC though it's not just a couple of little things. Fender went through some widely varied changes in the Bassman Head.
To me the aa864 is the sound I want the ab165 isn’t a bad circuit but if I can buy a cheap ab165 and mod it to an aa864 circuit I will
 

Paul G.

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True story: In the early 90s, I brought my dead stock AB165 to Tony Bruno (he was just a local tech in Queens at the time) for a service. When I went to pick it up, my friend went with me. Tony plugged it into a Marshall cab so I could make sure it was working ok, and my friend flipped at the tone. He said "I'm getting one of those!"

Eventually he found a nice unmolested AA864. I told him it's not the same amp, and he said "No, it's earlier, pure Blackface so it's better." He had it serviced (by Tony). He had Larry Rodgers build him a new head and speaker cab, loaded it with good NOS tubes and Fane speakers to get the ultimate amp. All the "best" stuff. It sounded good -- until you put it next to mine with JAN Philips tubes and a ratty old Allen speaker cab with some reconed Jensen Concerts. Then it was like night and day.

After spending gobs of money on "the best" of everything, he sold the amp. I got mine in a trade -- a Thomas Organ WaWa pedal (worth about $50 in the 80s) and $100 cash. Still have the amp. Put it in a combo because I'm old, but can revert back any time I want.
 




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