Hrm with cf ?

[Roe]

I guess you are right
Minus the attenuator 470k and cold clipper

Hadn't thought of that...

even thoose two are broadly 2203 type circuits. 2203s are often modden, particularly the cold clipper is changed (or some of the voltage dividors)

[jelle]

More like the Bassman Ultraphonix mod Dumble did: trimming off some bass and high end.

I have not seen any high end reduction measures in a Dumble Ultraphonix. They are clear and incredibly open in the top end...fragile harmonics

Don’t know if all modded Bassmans have a cap over the anode resistor of v1b? The one you can find in this forum definitely has. That plate bypass cap trims the high end going to v2. Wether you hear it as less treble is another story. The creation of harmonics after v1b makes up for it I think. Maybe the cap is part of the fragile harmonics? Have you experimented with it Jelle?

https://ampgarage.com/forum/viewtopic.p ... 29#p456029

[rootz]

Jelle, the one I'm referring to is the modded Bassman, supposedly done by HAD. It's also in the stickies. Cap I mean is clearly visible on v1b. But as you already said: the mods are diverse. And this modded Bassman is not an Ultraphonix, right? I just know what my eyes can see: The Bassman has that cap and Taylors A&G does IIRC.

Anyway, the topic started about a HRM with CF and I'm straying from that. Sorry about that! The schematic is something I did build and mention before. This or a ripper type circuit would be feasible as a build IMHO. On a side note: I don't think the ripper was ever confirmed. Not that it means you can't experiment...

[jelle]

Jelle, the one I'm referring to is the modded Bassman, supposedly done by HAD. It's also in the stickies. Cap I mean is clearly visible on v1b. But as you already said: the mods are diverse. And this modded Bassman is not an Ultraphonix, right? I just know what my eyes can see: The Bassman has that cap and Taylors A&G does IIRC.

The modded Bassman with the cascaded gainstages/CF/MV structure did not have an Ultraphonix decal. Also the circuit and tome has nothing to do with the UP amps that have that decal. In addition, I do not see the typical UP preamp in that amp. Instead its a Fender Blackface preamp.

I am curious what that gain mod was called instead.

Also what is that schematic you posted? What is that based off?

Jelle