Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #158518  by NorthboundRain
 Fri Oct 06, 2017 1:50 pm
I'm curious about McIntosh power amps. What makes them unique, and how can i replicate that in an amp modeler? I use Fractal Audio products (AxeFX-II, AX8) but I'd like to keep the discussion generalized so that people Using Line6, Kemper, Positive Grid, etc. can also benefit. All these platforms have a Flat Preamp model that includes a flat power section, I generally use a TWIN style model preamp and then the power section from the Flat Preamp model.

The one trick everyone seems to know is to turn off (set to 0) the Tube/Power Amp SAG to mimic the response of the solid state 2300. Beyond that I haven't seen a lot of advice relating to the Power Amp stage.

I personally prefer Jerry's early 70's tone where I believe he tapped the Twin Reverb Preamp into McIntosh Tube Amps, so advice on those would be most appreciated. Were they powered by KT88 tubes?

What is the role of Negative Feedback in a McIntosh amp? Is it similar to a Fender amp, maxed out like a MESA Boogie, or completely removed like a Matchless?

What other Secret Sauce goes into the McIntosh sound?
 #158519  by williamsaut
 Fri Oct 06, 2017 4:56 pm
McIntosh MC Amps use output transformers just like tube amps. I've read that these "Autoformers" as they were called are BIFILAR wound unlike a typical transformers which have each coil wrapped on top of the next for each Impedance. Mac did this to reduce distortion inherent in audio transformers. Now, all transformers have distortion or otherwise color the sound of the amp. In guitar tube amps, this is useful and desirable. How a Bifilar wound transformer's distortion characteristics differs from a standard IE transformer is unknown. Macs were also push pull in design just like tube amps which is uncommon in SS power amps. So a modeled audiophile push pull tube amp with no sag might be the ticket.
 #158535  by williamsaut
 Sun Oct 08, 2017 6:16 pm
Thought it was about modeling a MC power amp with any of several modeling units out there not the Kemper specifically.
 #158536  by NorthboundRain
 Mon Oct 09, 2017 12:23 am
This thread is about creating a models of various MC power amps. The intent is to learn about the specifics characteristics of MC amps and allow people to use that information with whatever modeling platform they may have.

I'm currently working under the assumption that MC amps have a high amount of Negative Feedback compared to Fender amps. It makes sense and sounds right in my model but if anyone who knows more can correct me please do.
 #158548  by strumminsix
 Mon Oct 09, 2017 6:05 pm
Look into the Kemper amp modeling. But most will say that ultimate Jerry tone comes from: middle single coil + buffer to BF preamp + Mac + making 3 front loaded E120's move.

It'll deafen you but oh so delicious!!