Help, Zen Master Nelson!

[Neutron Bob]

In short, I miss the effortless output of Mr. Pass' creations replete with banks of output devices.

I am driving a modified pair of Infinity RS II speakers. For those familiar with them, they will make mincemeat of most any amplifier that cannot withstand their low impedance. I have reworked their internal wiring and crossovers, essentially guaranteeing that they will consume every watt available.

Conditions are improving at home, and I am thinking about two projects: one, putting my wounded PM1600 back into service (power supply), as a temporary amplifier; and two, building one worthy of hours of struggle and little aluminum chips on the workshop floor.

I have been looking at the A75 power output section, and have been comparing it with my existing blocks (complementary banks of 2SK176/2SJ56 MOSFETS, 24 total). Mine sports a 1.2 microHenry choke on the output line, plus a 5 ohm + .047 MF RC pair (beyond the choke) to ground. Why was this necessary?

I had a roommate pull the inputs while live years ago, while I was in the fire academy. The amplifier literally boiled a pair of EMIT ribbon tweeters. Could this have been the result of oscillation??

I am still smitten with the sweet song of rows of output devices!

Looking forward to the sweet sound of Pass!

Bob

[halojoy]

You still trust in Master Pass?

Well,
I think you should.
He is not often enough at our Forum. (has other commitments)
But when he is around
he sure manage to answers, what is most called for.

My guess he will give you his special treatment.
The one only he can give. ( = few words, but reliable words)

/halo - gives halo treatments - not anything else

[Neutron Bob]

Hey there halo!

Of course! I wish I could afford such production toys as in my wild single days...as my little girls grow up, daddy will have some again. For now, I will learn and enjoy the DIY Audio / PassDIY route!

I miss the days of listening to the Thresholds daily, as my life has taken a side road for a while.

With the Aleph, and now the Pass X incarnations, Nelson continues down the path of musical bliss. I have been a fan since the 80s.

[GRollins]

The inductor/resistor pair you refer to is there to ensure that the amplifier is stable. Some are, some aren't. Basically, it's a lowpass filter, put there to stop ultrasonic oscillations.
I think you can depend on the A-75 to behave properly without one. If you've been studying the schematic with the intent to build it, bear in mind that you'll need to increase the bias a bit if you want the amp to mate well with a low Z speaker.

Grey

[SuppersReady]

Hi Bob,

If you are seriously looking at producing the A75 amp, I have 2 amp boards and 2 PSU boards which I purchased from Old Colony Sound with the intention of producing a pair of monoblocks. I also purchased Holcos/Black Gates for the amp boards.

Having been distracted by the building of a pair of Alephs, these parts are up for sale. If you're interested then email me.

Regards

Paul

[Nelson Pass]

Say whatever happened to Kilowatt? Did he just get
frustrated and go away? What I liked about him -
the name said it all: Big Hardware. Big Vision.

Big Science.

(Why do you think we hired Cyclotron Guy?)

So I'm formally committed to the "The Beast with a Million
Watts" (peak 1 microsecond instantaneous power into a
screwdriver) amplifier.

With a little help from my compadres, maybe even CG,
we'll deliver in a few months.

MuuuHahahahahahaha........

[russbryant]

I'm going to Sears first thing and get the biggest screwdriver they got!! They will replace it no questions asked, right?

Russ in Tucson

[Nelson Pass]

It's midnight in Tucson. Go to bed already.

[cyclotronguy]

Get Nelson to tell the stacked Dayton Wright story. Screwdrivers indeed.....!

Cyclotronguy

[Kilowatt]

Say whatever happened to Kilowatt? Did he just get
frustrated and go away? What I liked about him -
the name said it all: Big Hardware. Big Vision.

Hi Nelson! No, I'm still here. I just don't visit this forum nearly as often as I have in the past simply because I don't have any audio projects going at the very moment, and am taking a break from audio for a bit. Of course, I still have my 6 x 200W amp partially done, and all the parts needed to finish it sitting around in boxes, but I am taking a bit of of a break from it, as I have put in many hours on it. I'm not working on the speakers now because it is winter and cold and snowy outside.

As of right now, I have been working more in the high voltage and pulsed power fields, and have been spending a lot of time at http://4hv.org . I still have the "big hardware" and "big visions" as always, and my current main project is this http://4hv.org/index.php?board=4;act...y;threadid=761 .

I am also building a 4kW Tesla coil with a 6" x 34" secondary.

I got really into pulsed power when I got this 34kJ 15kV capacitor bank (6 x 51uF 15kV caps), pictured below along with the Tesla coil, at a recycling plant for $150, and have great fun with it, shrinking coins and trying out new coilgun designs, etc. They are the capacitors I will use for my big lateral disc cannon, linked above.

Here's some of the other stuff I've been doing lately.
http://4hv.org/index.php?board=4;act...y;threadid=725
http://4hv.org/index.php?board=3;act...y;threadid=691

I can't say which I have more of a passion for, pulsed power or audio, but I love both, and someday, perhaps next summer, I will resume work on my amp (not the REALLY big one, just the pretty big one) and speakers.

I'm really impressed how much this forum has grown, and how fast the replies are these days! It is quite wonderful indeed, and I am still very glad to be a part of it.