Jeff Rowland amp in unbalanced mode

Mordante - once it has input transformer it is truly balanced. Transformer has perfect common mode removal except for high frequencies where balanced input is defenseless anyway. To answer your question - Icepower datasheet for 200ASC (my Rowland 102) shows balanced input and I can see transformer inside on separate board.

Icepower switching frequency is too low (0.5MHz) to radiate and sharp switching pulses are filtered out by the output filter but nothing is 100% perfect and in addition there is still capacitive coupling. I would use common sense and for device that switches high currents at high speed I would use balanced cables with good shielding. My Rowland 102 does not even have unbalanced input - I respect Rowland's decision.

Guidocorona - There are two styles of class D output. One, like Icepower, uses single supply voltage and changes direction using mosfet full-bridge while the other style, like Hypex (Channel Island) uses two voltages positive and negative with mosfet half-bridge. First style sounds a little closer to tubes (even harmonics) but has half of supply voltage (DC) on both output terminals (doesn't bother me). Also bridging amps is not possible since it is already full bridge output. My small 102 has the highest bandwidth of the tree you mentioned and I don't listen very loud. I read your other posts on the PC1 and since you mentioned that my 102 is "eligible" I'm very interested. I have to upgrade speakers first (major expense) then I'll move to power supply. I'm sceptic about things like that, but I remember that at the beginning I was sceptic about interconnects and speaker cables - not anymore. Keep us informed! Is it expensive? I read review (AudioEnz) of 102/Capri and while Capri is better of two (exceptional) 102 is not bad, especially for the price.

Guido - www.audioenz.co.nz/2007/rowland_capri-102.shtml

Guido - 102 took close to 400 to break in. My setup so far is a little bit crazy since cables are the most expensive part of the system (Acoustic Zen Absolute XLR, Acoustic Zen Satori Shotgun) but I treat them as non-perishable items and therefore invest more for the future. Acoustic Zen Satori has a little "round" lower midrange which is blessing with Icepower. Lean sounding cables should be avoided. Strange (sterile?) top end according to many people is in my opinion related to limited bandwidth of Icepower (102 ~ 80kHz, 201~ 65kHz). Bandwidth limit is introducing some phase shift at 20kHz and perhaps wrong summing of harmonics. Other explanation?

Guido - I don't thing is changing anymore but I haven't counted hours.

I wonder what came earlier 312 or 501. It is possible that Rowland requested (or made) some changes to Icpower module based on previous experience. There are also some external components like input transformer and possibly mains filter. It would be interesting to listen to the same amp with and without PC1.

As for steril sound - my experience is very limited but I suspect that very clean sound might create impression of sterility or lack of dynamics (distorted guitar is lively in comparison to clean jazz guitar). When I upgrated from integrated solid state amp to Benchmark DAC1 + Rowland 102 I got impression that some instruments are missing - it sounded too clean.

Guido - so it's entirely possible that sound improvements you heard are due to something different than PFC (wiring, shielding, power filtering, input transformer or mods to Icepower 1000ASP module). Often companies don't apply improvement to less expensive modules for marketing purpose (more money - better sound)

Guido - I forgot about another important factor - speakers. I heard that Icepower sounds great with some speakers (like for instance Usher BE-718) and not so great with others. It might be sensitivity to type of load speaker is presenting. Initialy first class D called class T had output filter outside of feedback having low Damping Factor and big dependance on the speaker impedance characteristic. Icepower has output filter inside of the feedback but nothing is 100% perfect. It would be great to compare 501 with 501+PC1 on the same speaker. How PC1 is attached to amp - is it external or requires mods to amp?

Guido - I bought 102 + Benchmark to use only one pair of XLR interconnects (noisy environment). I decided against Bel Canto S300 since it was more expensive while not built as nice as Rowland. In my opinion Rowland's decision to put only XLR connectors was mature (not trying to please everybody). I know it wasn't for the savings of two RCA connectors since case is milled out from the single block of aluminum. Today I would probably go for Continuum 500 integrated.

I wonder if there are RCA-XLR adaptors for the output of preamp that preserve balanced cable configuration (transformer?). I know that people often have very expensive unbalanced interconnects and wouldn't change them. Transformers are not completely benign since they introduce small harmonic distortion at very low frequencies. On the other hand sonic difference, I heard of, is at higher frequencies, balanced being more "airy".

I'm a bit confused here - 200ASC module in model 102 is already regulated (nature of SMPS). Where PC1's voltage is injected?

Thanks Guido