Building a Slash S.I.R. #34 / #36 Amp

[Antonio_SM]

Hello, how are you? I hope they're all right.

I'm a big fan of Slash's sound on Appetite for Destruction and Used Your Illusion. It is known that he used amplifiers rented by the former company S.I.R., located in Los Angeles. In short, for the AFD it was number #36 and for the UYI it was #34 and both modified by Frank Levi.

As a way to replicate the sound, I decided to make an amplifier based on the Marshall AFD100. However, the sound of the amplifier was still not what I expected, something was missing, it didn't reach the tones I was looking for. After talking with many technicians and people who are also fond of this type of sound, I arrived at a layout and schematic that involves the two modifications.

Tony Dorris gave me this wonderful layout and I made some adjustments from there.

My amplifier has 2 channels, one Plexi and the other JCM/JMP, with individual equalizer, master volume and gain. They just share presence. On the JCM/JMP channel, I have the possibility to use stock (2204), #34 and #36. I have 5x 12AX7s in the preamp and 2x 6550s. I also have a tube buffered effects loop.

These are the layouts and schematics we used for the modifications.

Frank Levi #34-#36 Layout.pdf

Frank-Levi-_34-_36-Schematic.pdf

These are some photos of the inside of the amplifier after the modifications.

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I'm open to assembly suggestions and also for circuits #34 and #36.

Thank you all!

Kind regards,
Antonio.

[Mark]

I have been interested in this amp too. Have you seen the Headfirst page, there is a lot of good info there.

https://headfirstamplification.com/mods ... %26-repair