#133555  by James-T
 Sun Oct 27, 2013 6:42 pm
Since acquiring the AXE FX Ultra I'm becoming a bit more educated on guitar amps. So this is the question I just can't understand yet.

If the preamp is the key to tone and the power amp is intended to be transparent and boost the output, what is going on with the Mcintosh brand power amp which gets you to the signature Garcia tone?

When you hear folks talking about linear and ultra linear what are the talking about?

On that topic what are the options for Macs? I notice some units are ridiculously expensive while others are quite reasonable. Were any designed for guitar amplification or was it some sort of happy accident that the Dead stumbled upon this particular configuration?

Let me ask this another way. If you were to take the SMS Classic and run it through two equal power amps, one being a Carvin just as an example and the other being a similar output rated Mcintosh - what would be the sonic difference? It it in the EQ, or in the clean headroom?

The limitation, (if there is such a thing with the fractal) is it simply does not give options for power amps. It's all focused on preamps and does an excellent job at that.


James :smile:
 #133556  by Jon S.
 Sun Oct 27, 2013 7:20 pm
I think it's the "belly effect!"* :lol:

* http://rover.ebay.com/rover/1/711-53200 ... =824&kw=lg

 #133557  by williamsaut
 Sun Oct 27, 2013 7:34 pm
I remember reading someplace that the fact that McIntosh amps use (used) "autoformers", which I believe (tech guys can clarify), is just another word for transformer But are multi tapped so you get full rated output as long as the speaker load matches where you've got them hooked up (tapped). These output transformers are almost NEVER used on solid state amps because the load carrying capability (impedance) very closely matches the speakers unlike Tube Amps which by design need output transformer. NOT ONLY due these SS McIntosh amps have output trannys to make Speakers interact with them much like tube amps, They were not ordinary transformers. Most transformers are two big coils of wire with "taps" soldered at different points along the way to achieve the different output load match. This is inherently inefficiant due to the fact that the taps further away physically from the primary winding are effected less by the fields set up by the tranni. McIntosh 'Autoformers' were wound in a different way which is more time consuming and expensive but better. I think they are wound as a different winding for each tap and layed out on top of each other BEFORE winding or something like that. Other than that, there's something called a slew rate which is how fast an amplifier can create rapid sound reproduction (voltage spikes) on demand. The higher the slew rate the faster the amp. I'm sure that this can have an audible difference and most high end amps are more responsive. My 2 cents, hope someone corrects me if I'm out in left field. All I know is my MC50 is the heaviest 50watt amp I've ever seen. 28lbs. As heavy or more that a 50watt Fender Bassman head. It's the transformers. And Fender is famous for it's big iron as it is.

 #133560  by Smolder
 Sun Oct 27, 2013 9:37 pm
I think your being a little too absolute...

Many guitar players derive tone and distortion from the preamp... slamming the front end with humbuckers, a boost, or overdrive pedal will get some nice and very controllable distortion. But power amp distortion from tubes is pretty nice... lot's of that comes from over driving the phase inverter on a push pull amp. The McIntosh solid state amps are designed to deliver some of the warmth of a tube amp... not many do. A crown for instance, in a Jerry rig, isn't likely to be pleasant.

A twin is considered clean even from 2-8 on the volume knob... but what guitar players consider clean isn't the same as an audiophile would... though some slight distortion and warmth is still desired in the audiophile world... the last thing you would want for guitar amplifiers is absolute clean reproduction... it sounds sterile. In fact, I've heard folks describe guitar amplifiers as 'distortion generators'.
Last edited by Smolder on Mon Oct 28, 2013 6:43 am, edited 1 time in total.