I don't come here as much as I used to, but I had a little time to kill and found this thread very entertaining. May have to return more often.
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Pass Labs declines to spec their amps into 2 Ohms. Stereophile’s measurements of Pass Labs amps into 2 Ohms have resulted in a mixed bag of results. Interestingly (well at least to me) some of these "objective" results might be deemed either positive or negative depending on one’s perspective. Pass Labs has a somewhat unusual way of specifying their amplifiers. They are not unique in that they like others before them underrate their output into higher impedances that in turn makes their output into lower impedances appear perhaps more academically elegant. On the other hand they seem to spec their amps to reflect their "Class A" output when it appears as though these seem to be more like some Pass’s earlier "Class A/AB" labeled amps (albeit with perhaps greater 4 Ohm "Class A") in that that above a certain output they can produce more power in "Class AB" mode. Never mind, that there exists some skepticism regarding Nelson Pass’s use of "Class A" "Class A/AB" "Class AB" labels. Depending on one’s choice of criteria, the results might be perceived differently. IMHO, they are not generally especially qualified for 2 Ohm duty. |
NPN mosfets used by GamuT N channel mosfets (not npn) can generate larger amounts of current, but it’s the "complimentary" P channel that has the problems. To build a push/pull a/b amp that has just N channel top and bottom, the design has to be compromised to a degree, compared to when doing to same using N and P channel mosfets in class-A/B configuration. MOSFET transistors used in industrial welding, using only one or two per rail. Eventually, GamuT sold these N-channel MOSFET amps to high-end devotees across Europe.GamuT Di150 LE 250Wpc into 8 ohms 400Wpc into 4 ohms As you can see in the Stereophile test, the Gamut even with the N channel mosfets top and bottom couldn't quite do a close to doubling act like a BJT could, and they didn't do a 2ohm test load for reasons you can only wonder about. Cheers George |
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- 105 posts total