Here is a comparison of the 1965 Blackface Bassman AA864 that I bought not functioning ( all caps had been robbed out of it and resistors were metal film) vs my All original ( except for filter caps) 1965 AB165 Bassman. The AA864 was brought back to life with carbon comp resistors and mojotone dijon caps. All tubes are the same brand NOS rca 12ax7 in V3, jj 12ax7 in v2 for the ab165 which uses v2 for a second gain stage in the normal channel, aa864 does not, and nos sylvania 12at7 in V4. Mullard RI 6l6gc power Amp tubes. Cab is a 1965 fender bassman 212 loaded on top with a wgs invader 50, bottom is wgs reaper 55. Simple playing, not elaborate and clean to illustrate the difference between the amps with one original and one restored with modern parts.
Announcement
Collapse
No announcement yet.
AA864 vs AB165 Bassman
Collapse
X
-
Re: AA864 vs AB165 Bassman
Originally posted by jeremy View Postso what do you think of the two of em? clips are never as good as hearing and feeling the difference in person
Comment
-
Re: AA864 vs AB165 Bassman
The bias current is meaningless without knowing the plate voltage. If you want to compare the amps with an equal bias, you should match the wattage dissipation of the power sections. Power (watts) = current * plate voltage - mind you that the plate voltage and negative input voltage will change a little bit when you are playing and running a full signal, so your wattage calculation will have a small margin of error, but it's small enough that you wouldn't notice it in practice. Also with the amps that have the tubes matching (the AB165 has a hum balance too, right?), you could do a really useful mod by replacing the hum balance control with two 100 ohm resistors on the pilot light filaments to ground, and replace both trim pots with independent fixed bias controls for each output valve. That will let you get the desired dissipation while being able to "match" any two output valves so you won't have any extra hum/a need for matched pairs.
Comment
-
Re: AA864 vs AB165 Bassman
Originally posted by Myaccount876 View PostThe bias current is meaningless without knowing the plate voltage. If you want to compare the amps with an equal bias, you should match the wattage dissipation of the power sections. Power (watts) = current * plate voltage - mind you that the plate voltage and negative input voltage will change a little bit when you are playing and running a full signal, so your wattage calculation will have a small margin of error, but it's small enough that you wouldn't notice it in practice. Also with the amps that have the tubes matching (the AB165 has a hum balance too, right?), you could do a really useful mod by replacing the hum balance control with two 100 ohm resistors on the pilot light filaments to ground, and replace both trim pots with independent fixed bias controls for each output valve. That will let you get the desired dissipation while being able to "match" any two output valves so you won't have any extra hum/a need for matched pairs.
Comment
-
Re: AA864 vs AB165 Bassman
Fair enough. I can understand keeping those models stock - they're two popular Bassman variants and you're maintaining their value. If you had a less-desired Bassman (not saying they're bad amps - just less talked about), then I'd say go nuts and make the amp sound however you'd want it (whether that'd be stock or not) because resale for other Bassmans wouldn't be that much.
Comment
-
Re: AA864 vs AB165 Bassman
Originally posted by jeremy View Posthow much does a bassman head go for these days?- Tom
Originally posted by FranklySome people make the wine. Some people drink the wine. And some people sniff the cork and wonder what might have been.The Eagle never lost so much time as when he submitted to learn of the Crow.
Comment
-
Re: AA864 vs AB165 Bassman
Originally posted by jeremy View Posthow much does a bassman head go for these days?
Comment
-
Re: AA864 vs AB165 Bassman
i need another big amp like i need to shoot myself in the foot with a 12 gauge but it sounds like a fun amp! even my old dr is too loud to crank up most of the time, cant even remember the last time i turned on the dual showman
Comment
-
Re: AA864 vs AB165 Bassman
I picked up the '65 AA864 that was completely thrashed for 50 bucks at a garage sale. It was off in the corner. The chassis wasn't even installed and the faceplate that is covered was gone. I completely rebuilt the amp. All original all transformers and choke, but all caps and resistors had to be replaced as most were missing or just wrong. I rebuilt the front panel, and used a repro logo and aged blackface cloth. Looks legit. The all original '65 AB165 I picked up for 695. Well worth it. It sounds like liquid gold. However, when I first picked it up, I tried it out in the garage with an extension cord. I was barefoot when I fired it up. I was quickly reminded why power cords get changed to 3 prong and death caps removed. That funny tingling creeper up my left arm holding my LP. I quickly unplugged and plugged it back in the gfi outlet after flipping the ground switch. Talk about a blast from the past. These bassmans can be found cheap just have to look. The cheap ones aren't pretty and require work, but the juice is worth the squeeze.
Comment
Comment