mosfet citation 12

[mr l]

I'm interested in building the mosfet citation 12 design, I have some questions for anyone that can answer:

What was the maximum output power level for the HK 12, did it change with the MF 12?
Is it worthwhile paralleling output devices for more power?
Would it be better to bridge channels or biamp for speakers?

thanks,

[Nelson Pass]

60 watts, no, no, no, and not particularly

[jacky]

Anyone tried changing to fully complementary MOSFET output ?
Wonder if it would be better to go for complementary output , or stick with the original mod of N-channel MOSFET only. Understand that the distortion characterisitcs will be changed.
Also whether the drivers transitors can be ommited if going for complementary MOSFET output. May need to bias the voltage gain stage a bit heavier to drive the gate capacitance?

[Nelson Pass]

I think the fully comp version would be better, probably. The
original article aimed to minimize the number of changes to the
circuit, which kept it at "quasi-comp" topology.

[millwood]

Originally posted by jacky
Anyone tried changing to fully complementary MOSFET output ?

I have, running this thing off 36v rails. Not much audioable difference from the all n-channel version.

[Rjones5296]

Im building the PASS Citation 12 mosfet amp, I have a few questions first I notice the schematic in the pdf shows the audio output of the amp strapped with a cap .068 and a resistor 10@1w with the resistor to the output then to the cap with the other lead of the cap going to earth. this is sequence is reversed on the component layout on the diagram for the circuit board ? does this matter???

[GRollins]

That will be the Zobel network. It's there to keep the amp stable. No, it doesn't matter what order they're in. Kinda like the math thing they taught you in school: A+B=B+A.

Grey

[ingvar ahlberg]

This nice project keeps popping up!

Here are a few views and comments:
Citation12 repair!![/URL]

I´ve built both types and there is little or no audible difference so go for complementary which is even simpler. Both models benefit from raising bias, if using original heatsinks better stay below 200 mA/device, with good cooling around 1A/device really makes a difference.

[Rjones5296]

Thanks, I have all the parts for either circuit, Im just working out the details before I start. I have a service bulletin for the original Citation 12 which has came in handy, I notice the lead colors don't match the Pass mod article, so I want to map all this out first. The diode d3 i think, (don't have it in front of me now) that connects to pins 23 & 24 of the circuit board do ? I see this in the original circuit, Im seeing omitted in the Pass mod.***************************************
Has anyone considered adding an inrush current limiter to this mod ? I use these on all my builds, no more tube flash with tube amps at turn on, and with my SS amps there is absolutley no thump at turn on, and I can beef up the power supply's without the heavy current hit at turn on. ******************************

[ingvar ahlberg]

Dont bother
Send me Your post adress i´ll send You a pair of pcb´s which makes Your mod a lot easier. The mf mod is not as sensitive for turn on surges as the original design, but having transient protection on the psu rails is always a good routine.