http://www.roger-russell.com/mcintosh1. ... trymonitor
strumminsix wrote:I'm very curious what the monitor does. Input padding/limiting? peak limiting? output limiting...
mijknahs wrote:I'm usually using an MC2120 (with Power Guard off) into 1x12" E120. It is often (especially on the higher notes) making the "limit" light flash and I can maybe hear some smooth clipping at times. I've used it with the Power Guard on and it doesn't make much difference sonically (still making the "limit" light up). My Twin is cranked up anywhere from 6 to 8, so its a pretty hot signal.
I don't really think Jerry is getting this kind of clipping all that often (yes, on some recordings more than others - like the 5/31/83 JGB show). Usually though he sounds much cleaner to my ears. Especially in the Grateful Dead.
I think Brad explained the difference bewteen the Sentry Monitor and Power Guard in the above posts. I really can't explain.
no, jerry definately had some really clean bite. that "smooth clipping" of the sentry monitor is exactly what "hair" brad and i speak of as jerry almost always was in that power range. it's not a Dist+ or Mesa Preamp hairy at all.
The power guard simply monitors the actual output signal at the speaker terminals for a certain threshold then pads the input if that is met. So, if your not blowing out the input of the very robust input stage of the Mc, or pushing the amp to it's limits, then odds are, the power guard is working but not actually doing anything. so on or off Unpushed, wouldn't make a difference. The mc's VI limiter, or sentry monitor, monitors the output(voltage & current) at the output transistors output. if the threshold is met then the circuit switches on and limits the input of the driver transistor. jerry was known to bury the needle of one side of his Mc2300, 300 watts out of a 2 ohm tap is pushing a substantial amount of power and would have the sentry monitor("smooth clipping") always engaged. if jerrys mc2300 had a clip limit lamp it would almost always be on when he was playing. the sentry monitor is activated the majority of the time. a different scenario then running it at lower volumes vs. really pushing the limits of the amp.
the way jerry pushed his mc2300 would, imo, most certainly engage a power guard and limit the sentry monitor from reaching it's threshold and smooth clipping at pushed volumes. that is my theory on why a mcintosh without a power guard, or at least switchable on/off, is more in line with jerry's. also a lower wattage mc'amp would allow you to push the limits of the amp without needing 300 watts. but even a 50 watt mc'amp pushed is way to loud for the average bar gig.
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