Carr Artemus

[justaddsomeechoX]

Hello!

I've been interested in a good-sounding and low microphonics EF86 substitute in a Vox AC30/4-like preamp circuits.

So after some "research"I've found that cascode cirduits can reproduce some pentode preamp sounds quite nice. And one of the current production amps with such type of preamp is Carr Artemus.

So, I've drawn a basic amp schematic(based on guts I've found in web) with some values missing. And I think, that it might be interesting for some of you, guys.

So, the schematic.
[img735]http://cs620720.vk.me/v620720783/c592/aNPYBKkx6hI.jpg[/img]
And guts.
[img960]http://cs620720.vk.me/v620720783/c59b/ONtOf2k2cgw.jpg[/img]
[img960]http://cs620720.vk.me/v620720783/c5a4/q9TPWaIzhGw.jpg[/img]

I've tested the 12AX7 cascode(Ra=100k, Rc=1k5, other values in schematic above) in AC15-ish circuit, it sounds really good by itself and provides nice harmonic content when boosted (I use rangemaster clone with switchable input cap).

[Gaz]

Thanks a lot for sharing. It looks like you are really close and could easily tweak from there to your taste. Cascode is cool, but nothing special. It doesn't overdrive as easy as the EF86, but as an input tube that's not likely anyway. The gain is about the same, and I believe it's a little better for driving heavy loads like a TMB tonestack. Haha, if I were you I'd stay away from the huge poly filter caps and glue. Haha, so stupid.

[jazbo8]

I see Carr is still perpectuating the myth of AC-30 being a Class A amp... Wonder how much more the Solen caps add to the sound?

[Lummox]

Pretty close. Try these values for V1b.

R5 = 1meg

C4 = .0047uf

C5 = 250pf

C6 = .001uf

C7 = 150pf

I'll look it over a little more tonight, when I have time, and add what I might have missed.