Good question. The behavior of this amplifier is unique in my experience. The manufacturer says that insertion of the brickwall filter and disregarding the RF oscillation and any flattening of the output waveform (they suggest looking for flattening of the residual distortion waveform), the real power output of the ZR1600 remains a matter of opinion. I will call it a 200W/ch (4 or 8 Ohms) amplifier for now. I may change my opinion later.
This amplifier is NOT EVEN a 200 wpc amp if it is going into oscillation at that point. As such, John was correct in stopping his testing at that point as anything beyond that point was nothing more than "electro-garbage". This is true regardless of how much out of band filtering one applied.
As for this amp NOT meeting spec, what's new about that ? The earlier Sunfire Cinema Grande amps would not meet spec either. With all 5 channels driven simultaneously, it fell short of it's RMS power rating ( 5 x 200 @ 8 & 5 x 400 @ 4 ) according to testing that i've seen. While i know that Sunfire has performed quite a few changes to these amps, especially the "Architectural Series", one has to wonder how closely these "Carver Pro" amps are related to Bob's Sunfire product line ? I also have to wonder if Bob has anything to do with these products at all or if he's simply farming out his name ?
Having said that and before all of these "Carver Pro" fans start jumping all over me, they should know that i currently own a Sunfire Signature, Sunfire 300, Sunfire Cinema Grand, Sunfire Cinema Grand Signature and a Sunfire Theater Grand Mk II. For sake of clarity, the Theater Grand Mk II is feeding the Sunfire Signature to drive my mains on my HT system and the Sunfire Cinema Grand Signature to drive the center, surrounds and two subs in that same system. The Sunfire Signature has had factory upgrades performed to it in order to better deal with the low sensitivity, low impedance speakers that i'm running. I was told that these upgrades are not available for their multi-channel units. The Sunfire Cinema Grand that i own is currently being used by my Father in his combo HT / 2 channel system and my Sunfire 300 is sitting in the box as a spare amp should i need one.
As far as the sonics of the Sunfire amps go, they aren't bad but they lack liquidity, air, separation of notes, blackness of background and bass impact. If you have one of these amps or are thinking about running one, i would HIGHLY recommend taking advantage of their balanced inputs. They really are much better sounding and quieter using this approach. Other than that, having the low impedance mods performed to the big 2 channel amp REALLY helped out the bottom end, but the amp still isn't going to win any contests for "sweetness". What these amps do REALLY well is to present a consistent presentation regardless of how hard you are driving them. While most amps tend to fall apart with complex recordings during high level playback, these amps retain their "composure" even when hammering out massive SPL's. It is almost like they have a never ending lung capacity, regardless of how long or loud of a listening marathon that you are willing to run. For the record, i have sent my Sunfire Signature into thermal overload two different times, so you know i was standing on the throttle HARD !!!
As mentioned above, i know that they have made many upgrades to these amps outside of what i've had done at the factory. The funny thing that i noticed is that many of the areas of performance and design that i questioned Sunfire Technical Support about via phone conversations seems to have been addressed after i brought them up. While their initial responses to my questions and comments were always "that's not necessary" or "you don't understand how this amp works", i've been told that many of the specifics that i've brought to their attention have been "dealt with" via revisions and upgrades in newer production models. While i think that this is great for those looking to buy an amp, i just wish that they would perform these "upgrades" to the amps that their customers already own as requested. After all, i ( and i think most other owners ) would be willing to pay for these upgrades just to bring the amps up to current production standards. As such, i have to wonder how many similarities there are between the Sunfire amps and the Carver Pro amps and if the two "different" companies have similar product support policies.
As a case in point, my original Sunfire Signature ( 600 wpc @ 8 / 1200 wpc @ 4 ) only had two 10,000 uF caps in it. Quite honestly, this is a ridiculously low figure for an amp this size. As mentioned in this thread, the Carver Pro is utilizing 60,000 uF's, even though it is rated for HALF the power that my two channel Signature is rated for. Unlike the Carver Pro though, my Signature will meet and beat its' published specs and do so with ease. As Brian noted, it appears that the Carver Pro amps have had some corners cut in order to increase profit margin for the manufacturer and make it easier for them to produce.
As such, i would have to agree with Brian and John in saying that this amp IS a horrid mess in terms of specs and that John did test the amp under "real world operating conditions". As such, his results are probably closer to what one would experience during normal operation since nobody i know uses an active 20 KHz low pass filter between their preamp and power amp. What this means is that this amp "may" sound good but it probably doesn't even sound as good as the Sunfire amps that are current production models. Not only do they offer more power, but they deliver it in a much cleaner fashion using better quality parts. This is not to mention that their based on an 800+ KHz switching frequency, which is even faster / further away from the audio spectrum. Sean
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PS... Yes, i've heard some of the other amps of this nature and was not "blown away" by any of them. None of these "high efficiency" amps has ever come close to delivering the sweetness and impact of a high quality Class A or high bias AB amp in my opinion. This includes the Acoustic Reality amps also.
