Pass Current Drive First Watt amplifier

[Colin]

The first watt is the most important watt.'

With super-sensitive big ole horns, it is the first watt that really matters. For most music applications in many typical rooms, all big ole horns really need is a good two-ten watt amplifier. Now Nelson Pass, the God of monster amplifiers is making a limited run of current drive amplifiers. I readily admit that I do NOT understand the electronics, but I do respect the opinion of ex-Stereophile editor Dick Olsher, so I thought this was very interesting.

http://www.enjoythemusic.com/magazine/equipment/1204/firstwattf1.htm

[sunnysal]

but these are intended for single driver speakers only, it only works its first watt magic when there is no crossover.

so we still have to wait until he points his guns at horn speakers. tony

[Daddy Dee]

Colin, thanks for the post.

I can't track the electronics, but sure would like to hear this combo.

Hopefully someone on the forum will try out these rascals. I'd sure like to hear what this sounds like. One thing, Mr. Olshner didn't say much about how these sound. I was wondering about that.

[leok]

The First Watt produces a current version of the audio signal (which generally exits a source as a voltage version). Most speaker systems (and most individual speakers for that matter), including Klipsch, are designed to produce air pressure versions of voltage signals, not current signals. Air pressure versions of current signals will have substantial frequency response peaks and valleys and probably regions of much more complex non-linearity.

Interesting? yes. Music? probably not.

Leo

[sunnysal]

Leo,

As I mentioned above, pass is not suggesting these amps be used for most speakers, he states very clearly these current amps were designed for specific single driver speakers from Fostex and Lowther. He spent some time describing the pros and cons of current versus voltage amplifiers in his first article on the subject:

http://www.passdiy.com/pdf/cs-amps-speakers.pdf

he now is showing a way to design crossovers for these types of amps, to allow people to experiment with them on "normal" speakers. makes for very interesting reading;

http://www.passdiy.com/pdf/CurrentSourceCrossoverNetworks.pdf

Mr. Pass is a true audio enthusiast and his experiments with class A amplification and many other aspects of SS amplification have indisuputably advanced the audio art. ask John Curl, Bruce Candy and any other amp designer about Pass and they just shake their heads, he is a giant among audio engineers. I love the fact that he shares so much information with the audio community as well, no secrets from him.

warm regards, tony

[Tom Adams]

FWIW...the guy that sits across from me (Lyn) was telling me an interesting story about Mr. Pass. It seems that Lyn's brother (Lonnie) along with two of Lonnie's friends worked with Nelson back in the early 70's and while Nelson had this concept/notion for what became known as the STASIS topology, it was Lyn's brother that made it become a reality. The company was Threshold (as I'm sure many of you know) and one of their early amps was the CAS-1. Lyn has one and it still works!

At some point, Nelson sold the STASIS patent to Nakamichi and Lonnie & his friends felt that Nelson "sold them out" so they left and formed their own company Coda-Continuum. I'll leave out Lonnie's opinion/commentary Lyn passed along about Nelson Pass. Suffice it to say, as it is so many times, Mr. Pass has had some major help along the way. Kelly Johnson of SR-71 and U-2 fame once said, when recieving a lifetime achievement in Aerospace, something to the effect that his award should go to all the folks that made his ideas come true. For without them, his ideas would've remained just dreams.

Tom