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Fractal Audio AMP models: 65 Bassguy and Dweezil's B-man ('65 Blackface Fender Bassman, AB165)


* EDIT: Up-to-date information is available in Yek's Guide to the Fractal Audio Amplifier Models *

65 Bassguy: based on ’65 Fender Blackface Bassman (AB165 circuit)

Dweezil's B-man: based on '65 Fender Bassman (AB165), Bass channel, modded by Blankenship

We already discussed the ’59 Tweed Bassman. This version of the Bassman is a very different animal, which dates from the blackface/CBS period. Note: Fractal Audio modeled Dweezil Zappa’s personal amp.

The Blackface Fenders were produced between 1964 and 1967. Pre-CBS blackface Fenders are in high demand, and not as expensive as the Tweed and Brownfaces. The blackface name originates from the black tolex and controls panel. More information.​

The ’65’s AB165 circuit is dirtier and “nastier” than the previously discussed version of the Bassman ('59 Tweed). The AB165 gets Fender into Marshall territory. If I’m not mistaken this particular amp is an early ”CBS”-era model. That’s when CBS owned Fender (and in the opinion of many wasted a lot of great Fender circuit designs). That’s why the AB165 is not regarded as a true blackface amp by some. But it's still a great amp, just listen to Tyler Grund's clip below, or the model. More background information here and here and here.


The 65 Bassguy was matched to a 65 Bassman that Dweezil sent me. It's a vicious amp that sounds more like a Plexi than a Fender. It's the infamous AB165 circuit which is very crunchy and bright and does not sound like your typical Fender. I was told it is stock. Definitely not your father's Bassman. Has a pissed-off Marshall vibe to it."

(Qauntum 3) "It's Dweezil's Blankenship modified Bassman. Dweezil's Bassman has two channels like a regular Bassman. The Normal channel is "normal" and corresponds to the 65 Bassguy Nrml model. The Bass Instrument channel is modified and that's the basis for the new model (Dweezil's B-man). It has a boatload of gain and sounds more like a Plexi than a Fender."​

The AB165 puts out 50 watts through two 6L6 tubes. Cliff:

AB165 uses 7025 preamp tubes (which are relabeled 12AX7). The phase inverter, however, is a 12AT7. The secret to the AB165 is the summing stage. It uses a inverting summing amp to sum the Normal and Bass inputs. This stage clips, because of all the local negative feedback, quite hard."

It has two channels: “Bass instrument” and “Normal”. Fractal Audio gives us three models of this amp: 65 Bassguy Normal, 65 Bassguy Bass and Dweezil's B-man. The last one is based on the Bass channel, modded by Blankenship.

The Normal channel has a Bright switch, which is enabled in the Normal model. There’s no model of both channels jumpered.

The original AB165's controls are: Treble, Bass, Volume Bright and Volume Normal, and the already mentioned Bright switch. In the model the Presence parameter is maxed, because the real amp has a fixed Presence setting inside. There’s no Middle tone control, so keep this at “5” in the model for authenticity. No Master Volume either, so keep the Master control in the model dimed.

Note that the range of the controls on this amp is 1 to 10, while the model's controls range 0 to 10. Here's a translation table, created by forum member Barhrecords.​

Dweezil's modded Bassman has no tone stack.


"The actual amp has no tone stack so for maximum authenticity all tone controls would be at noon (but don't be afraid to tweak them). In the actual amp the Treble control is re-purposed as a Negative Feedback control. Experiment with different values of Negative Feedback. Lower values are looser."​

The Bassman provides two inputs per channel. Fractal Audio models of Fender amps are always based on the input with the highest input level. To get the equivalent of using the lower input, set Input Trim to 0.500.

Unlike the other Bassman, this Bassman was used with a 2x12 cabinet, with Jensen or Oxford 12” speakers. Find the 2x12” Fender stock cabs on this page. Marshall cabs also work well.

A selection of videos on YouTube, including one from our forum member @Gamedojo (Tyler Grund).

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Fractal Fanatic
It's a cool amp but I wish there was a more typical blackface Bassman too. I had a 65 Bassman I liked it a lot. Much cleaner & warmer than the Axe model. Not to hijack the thread but is there another Fender model in the Axe that could get closer to the typical blackface Bassman? And thanks Yek for all the great info here & on the wiki!


Fractal Fanatic
I had one of these in the early 80's; bought it for $100 but it wasn't "a Marshall" so I flipped it for $65 when one of the tubes went wacky.

...always bummed that I didn't keep it; would love to have it now...


I've got a 1965 blackface bassman for a year and a half, it's an incredible amp. I'm willing to try Fractal's model when I receive my AX8 in the next weeks :D


Thanks for this great overview!

I´m still curious- what are diferences soundwise between the pre CBS Blackfaces with the AA864 circuit compared to the AB165?
You can even buy AA864 Mod Kits for the AB165 Version, yet there are also many players who prefer the CBS over the first blackface?
Somebody knows anything about that?
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