Pass Hybrid


2002-08-14 1:18 pm
mozfet said:

I have build this amp and there is a problem. I have destoy five couple of mosfet irf540/irf9540 because when i put power on the voltage betwen the grid and the source of MOSFET exed 20V.
I thinka possible solution is using zener diode 1n4737 but not tested

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
Actually there are two problems that I can see. A Zener
across the current mirror will prevent broken Gates on
the P channel Mosfet, and the 100 ohm power supply
decoupling resistors should be at the rail inputs so
that the decoupled rail voltage should include the
Sources of the Mosfets.

yes i bought two pcb`s of Generoso Cozza.
Result by switching on: all power mosfet were burning.

After consulting Generoso, he told me " the circuits must work"
The i build the circuit, myself, with the same results - burning Mosfets.

After a while i decided to build a Son of zen of Mr. Pass, which worked and sounds really good.

Dont build or buy the schematic of Generoso Cozza


Opinion !

I Think That All Pure Things Are Made Of Simple Stuff.
So Why Are You Trying To Lineraze Active Devices...:confused:
The Only Linear Road Is, To Use The Most Linear Active Device +
Resistor In Single Ended Configuration.
Yes, There Is A Lot Of Dissipation.........But This Is Only Way To
Pure Audio Heaven. So Then You Have Only A Few Watts, But
In The Most Linear Maner. So I've Got Only Three Words 4 U :

Batteries + Resistor + Active Device (Vacuum Tubes + MOSFET) :D

Enjoy Your Music.........;)


Disabled Account
2002-05-15 1:12 pm
uros vicar

'The Only Linear Road Is, To Use The Most Linear Active Device'

Wrong i fear....there is no such thing as a linear active device......a single-ended output generates copious amounts of even order distortion artifacts....Nice if you want your amp. to be a musical instrument, not so good if the truth and nothing the desired objective.... :)
Uros Vicar, mikek

There are many roads toward the light. Each has to take his own path.

Enjoy the music. That, and the satisfaction of building it yourself, are all that counts. We all benefit, the more we learn from each other.

The concept of this design is very interesting. I think that there is a lot of promise in tube-SS hybrids. In this case, eliminating an output transformer certainly reduces the cost, and removes the OPTs non-linearities... each design is a different set of trade-offs.

Unison & Pathos both have commercial products like this which are highly regarded. A local fellow is working on a hybrid/SE mosfet amp. The prototype is very good (and spread out all over his living room floor -- quite a sight).