"very sensitive to other equipment and cabling"
Capuccino,
very interesting posting ! ... I think you are right
Power cables can make a huge difference and of course also interconnects. That's also why J.Rowland developped his PFC1
Read what Gary Koh from Genesis says about class D ...
interview:
"
N.D. -I would like a few words about your class D amplification, which is a relatively modern implementation in the high-end audio business – it has been mostly seen in consumer applications. Do you believe that it might even account for the future in amplification?
G.K. -The first working model of a class D amplifier was designed by John Ulrich, it was called «The SWAMP» (SWitch WAve AMPlifier) and was delivered in 1976 by Infinity. One of the founders of Infinity, Arnie Nudell was also the one who founded Genesis. In 1991 Infinity was already using class D amplifiers; we’ve been using class D amplifiers for the past nineteen years!
N.D. -So it is a myth that class D is not adequately developed to serve its purpose…
G.K. -It was not developed adequately. Until a couple of years back, class D amplifiers… I could not sit and listen to, they did not deliver music. Class D was very, very good for bass, which is why Genesis speakers used class D amplifiers since 1991 for the servo-bass part of the system.
My class D amplifier came with a story. I was trying to find a more reliable, a better amplifier for the bass and I reviewed all the available class D amplifiers; all those that were available as modules or as designs. After about two and a half years, I finally settled with the Hypex amplifier module, for the bass. Around that time, I don’t know if you are familiar, but I developed a tube amplifier for Genesis...
N.D. -Yes, I saw that they are sold out!
G.K. -The tube amplifiers are sold out… The tube amplifiers were done for only one reason: They were proof of concept that a cheap amplifier can be used to drive Genesis loudspeakers. You see, the designer of Genesis Loudspeakers, Arnie Nudell, was very famous for making speakers that are very difficult to drive; they had very low impedance, they demanded a lot of current and a lot of dealers said that -at that time the equivalents the 5.3s were like, I think, $14.000- to drive a $14.000 loudspeaker they required a $30.000 amplifier! I told them “no, this just means that the amplifier is not designed properly!”. So, a very famous dealer -I won’t mention his name- looked at me and said “if you think you can, you design an amplifier that’s cheap and can drive these spakers!”. It took me… two years; two years later I brought a pair of the M60 monoblocks to his store, I put them down and said “OK, which preamp do you want to use?”. He picked a preamp, he connected it in, then we connected it to… that was the 5.01 and it drove it perfectly. So he lost his bet; I won my bet… Here was a $4.000 amplifier that drove, at the time, a $14.000 loudspeaker!.. The problem with tubes, though, is that the moment you buy the amplifier, it begins to deteriorate, so I didn’t want to really continue making those. However they were a proof of concept; if I can design it -and I am not a famous amplifier designer- then everybody else can design it! That’s the amplifier, I’ve proven my point that you don’t need an expensive amplifier to drive the Genesis speakers.
N.D. -It was like an etude, a study on the subject.
G.K. -It was a proof of concept, it was a study.
N.D. -Your current class D modules, do you design them or are you still using Hypex?
G.K. -I still use Hypex, but I heavily modify the Hypex modules. The reason is that if you listen to a lot of class D amplifiers, they don’t have what I call the “soul” and the emotion of music. You know, you don’t feel that the singer sings of a lost love or you don’t feel that the singer is actually in love with you and she’s singing to you. The problem I solved -after actually discovering that it wasn’t a problem of the module- was the problem of the power supply. I designed a power supply that works perfectly with the class D module, to deliver that soul and emotion.
N.D. -Is it a linear power supply or a switching one?
G.K. -It is a linear power supply… I couldn’t make a switching power supply work; I tried.
N.D. -I know it is quite a bit of a challenge, but, if anyone can do it, I believe it’s you.
G.K. -Thank you!"
