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Discussion in 'Amps and Cabs [BG]' started by MascisMan, Nov 7, 2006.
sets would range from 45 minutes to 2.5 hours (with breaks)
There is more than one crazy bass player that does it. I wouldn't do it though...not without a plan b.
I wouldn't try it. The manual clearly states that it will operate into a 2 ohm load, but the MOSFETs will run excessively hot. After a certain period of time, a thermal protection circuit will mute the output stage until the MOSFETs return to normal operating temperature.
Edit: Actually, go ahead and try it! If yours has a meltdown, I've got a real nice one for sale in the TB classifieds!
I wouldn't do it; however, I would go trade my 600 for a BB750 thats designed for such a situation. That surprisingly sounds like what I actually did
If the manual says that it is rated to 2, then the output devices have enough current handling capacity to run at 2, and there should be no more risk than running a 4 ohm amp at 4. Overheat? Unlikely - it was designed to run that way. PA amps are normally rated to 2, and used there a lot, with no problems - it's not like running a 2 ohm load is rocket science or anything. Heck, if you bridge an amp into a 4 ohm load, each channel effectively sees 2, and a LOT of folks do that . . . .
Oh, and if his "Has a meltdown" that would be warranty, not a chance to make some undeserved $$$$ . . . . .
It actually says that the load should not go under 4 ohm in the manual. I called MB and they confirmed that a 2 ohm load on the M-Pulse 600 is a bad idea.
The engine in my car will run at 7000RPM, so I guess it was designed to "run that way." However, I usually don't keep it there for very long-that would be a very bad idea. This is directly from the Mesa M-Pulse 600 manual, verbatim:
"The optimum speaker load for your M-Pulse is 4 Ohms. You may use a cabinet (s) of a higher rating safely (8 Ohm) with no degradation in tone, however the amplifier will not produce its full rated wattage. Minimum load rating is 2 Ohms and while the M-Pulse will handle this lower load condition-and in fact produce more than its rated power, it is not recommended. Prolonged use of a 2 Ohm load will cause the power mosfets to run hot causing the protection circuit to trigger and mute the output signal until such time as the mosfets can return to a safe operation temperature. Avoid using 2 Ohm loads whenever possible."
Oh, and that was written by the folks at Mesa who actually designed the M-Pulse 600. I'm sure they have done extensive testing and know the limitations of their product.
Regarding "undeserved $$$$" comment, how do you know the OP's amp is still under warranty? I'm just tryin' to help a brotha out. Oh yeah, one more thing, when you see one of these, that indicates humor (or an attempt at it...). Something we could use a lot more of (IMHO, of course).
Regarding your car, if the engine specifications state that it can run at 7000, then is too should be OK. "Just because it can" does not mean that it was designed or rated that way . . . . . I am talking about Mfg. specs, not voodoo opinions of those who have no real knowledge of the amps internal design. A 2 ohm rated amp run at 2 should be as safe as a 4 ohm amp run at 4 - they both are at the edge of their rated specification.
On this one, Mesa is actually stating that they are not really rating it into 2 ohms. A true 2 ohm rated amp will run indefinitely at full power into that load without issues . . . . . . why they even mention 2 ohm loads is a mystery to me, unless they let some marketing boob write some of the specs . . . .
And regarding the $$$ comment, even if out of warranty, service is almost always cheaper than replacement. It boggles my mind that some folks just ditch stuff as if repair is not an option . . . . . Pop the power devices in most amps, and you are looking at a parts cost of about $10 - $15 each plus an hour or two of labor . . . . . . and typically, only one of two devices fail, and the amp shuts down before any more can go out. I would much rather kill an output device in the power amp than a preamp board - the power section is far easier to work on, and far simpler . . . .