Dear Audiomatic, I do not enter in the tech-war above
! My interest is in the phrase quoted: No, the two models that you have mentioned were only the most famous machines of Mr Mauro del Nobile. Other models were the 12A power amp, the first class A with 550 Watts per channel, 2800 watts in mono! this one was the first amp on the market (alongside with Deltec) that was using the SMD technology at that time (1992). Before the end of production two "signature" versions of this amp were produced: the Reference MDM (2x550Watts) and the Reference mono (2800Watts). Also the preamplifier was improved with a "i" version of the model 5 (1994). A very special MC phono cartridge was made till 1992. The first two products to hit the market with the "del Nobile" brand were the MDN 831 and the MDN 100 (pre+power amp) in 1986 with specs similar, not equal to the then modified 5+6A. The production, in the original market, covered the very top end of the demand. Prices were high but...with reason. 
Hi K-amps,
"PS: I just got a DH-500 at a good price. I am planning to get a second Trafo from a surplus store and make it Dual mono. "
Why not fix the PSRR of the design and fix 2 things - crosstalk distortion AND self induced PS commutation distortion. Running a second supply is a brute way to fix the first. Simple low level design improvements identically in both channels fix both. Elegant.
"PS: I just got a DH-500 at a good price. I am planning to get a second Trafo from a surplus store and make it Dual mono. "
Why not fix the PSRR of the design and fix 2 things - crosstalk distortion AND self induced PS commutation distortion. Running a second supply is a brute way to fix the first. Simple low level design improvements identically in both channels fix both. Elegant.
Hello,
I also own a set of the Swiss Physics Model 5a and Model 6. I recently change the MOSFET module because one of the previous module was dead. The pari of module that I purchased and installed in my Model 6 Power Ampifer was the ILP MOS248.
For further info, please click on the following link to the manufacturer's website:
http://www.ilpelectronics.com/support/docs/MOS248.PDF
I also own a set of the Swiss Physics Model 5a and Model 6. I recently change the MOSFET module because one of the previous module was dead. The pari of module that I purchased and installed in my Model 6 Power Ampifer was the ILP MOS248.
For further info, please click on the following link to the manufacturer's website:
http://www.ilpelectronics.com/support/docs/MOS248.PDF
jacco vermeulen said:
Hi Jacco,
Zener is only reliable to some extent but not that much brute protection when the mosfets are driving real world reactive loads down to 2 ohms....
We employ individual zeners of 7.5V 1W each directly soldered to each mosfet's [12 parallel pairs]source and gate terminals with gate resistors 220 ohms .
Secondly we also employ rugged gate drive limiter circuitry just inbetween the driver and gate resistors of output mosfets. to ensure that the gate voltage never exceeds the 8V reference voltage....
Hope you like it...
K a n w a r
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