Digital Amplifier Questions

B_Limo, in a lot of cases, the answer is... "It depends"... But here are some specifics as they have applied to class D amp I have used... ROwland M312, Merrill Veritas monos, Belcanto REF100M and REF500M, Rowland M925.

Q: Leave on 24/7?
A: Yes, in all cases... Takes at least 24 hours of playing time for all class D amps in my test set to reach peak performance after being off for a spell.

Q: Plug in its own AC circuit?
A: It depends.... Amps with high degree of power supply isolation like Rowland M925 do not inject much noise back into the AC line, others do. In all cases, you may get slightly better dynamics by plugging power amps in a dedicated outlet.

Q: Stacking or not.... RF leaks?
A: It depends again on degree of isolation... Newer amps like Rowland M925 and Merrill Veritas do not leak RF... Try moving an FM radio on top of them... You will not hear any additional hash on the radio... IMO stacking is OK with these... Both amps are based on Hypex NCore NC1200 modules.

Q: What power cords?
A. Use high current capable power cords... with class D amps, instant current swings/transients can be huge. Do not use analog cords for low power applications, nor old style "digital" cords like the old Shunyata VX.... They will "caramelize" the sound. Note that some cable manufacturers might have today new styles of digital-ready PCs that handle high current class D amps... E.g. Check with the Shunyata factory for their recommendations.

Let me know if you have further questions. G.

One other thing I would note about Class D amps is that they typically seem to have very high damping factors. That will play well with larger speakers taht can benefit with more control of the driver movements as a result of the high damping factor. My large OHm F5s use a 12" walsh style driver known to benefit from high damping in terms of bass control and articulation and that is in fact the result.

Due to high damping, Class D amps can come off as somewhat lean in other speakers. That is the case with my smaller Triangle monitors in particular. I have those set up accordingly to compensate and the results are still quite top notch. My Dynaudio monitors are more in between. I like the clean taut articulate bass that results with them as set up (see my system pics) but I could easily see where some might consider the sound a bit too lean despite the fact that the bas is all there and very detailed and accurate. it just won't be shaking the rafters, at least on most recordings.

OK Guido, now you've accelerated my desire to add a pair of pangea ac9 cords to my amps to go with the AC14ses on my line level gear.

I guess it never ends. :^}

B, I think excellent recommendations from Guidocorona. I know he has a big interest in Class D amps and probably has actually heard and spent time comparing the most of just about anyone I am aware of in these parts.

Hi Mapman, what is fascinating is that the NCore NC1200 modules do not seem to leak RF into the air regardless of power supply design.... Merrill Veritas use the basic non regulated Hypex SMPS that matches the power conversion module... While Rowland M925 uses a custom massive multi-regulated SMPS.... Neither amps generate any extra noise in an FM tuner operating near them.

Perhaps Tim can do the test on his D-Sonic powered by the AbleTech module and tell us results.

All, please note that if some RF leak occurs, that does not mean at all that the particular class D amp does not generate good music... the ICEpower ASP1000-based Bel Canto Ref1000 Mk.2 and Rowland M312 remain absolutely marvelous amps... Just do not stack an FM tuner just on top of them.

G.