"DEEP" CLASS A

[Paul86]

Excuse moi if this has already been discussed. But I recently found Blackie Pagano's website, an amp builder and repairman from NYC. And he states that "The dual 6550 / KT88’s are in a deep Class A operating point, with a relatively low voltage swing and very high current, running at their design maximum of 40w heat dissipation per tube. The transformers and tubes are running at full tilt, like a top fueler with the hammer down, even with no guitar signal applied.

The “low and hot” operating points for audio tubes are suggested by the original engineers of these tubes in the ancient tube manuals as giving a optimally pleasing and musical sonic spectrum with even-order harmonics predominating. These classic operating points are rarely exploited in the guitar amp design world as they yield lower power numbers than the typical higher voltage swing class AB operating points. Although “low and hot” operating points are rare in guitar amps they are revered in the world of underground audio as the operating points of choice for dimensional, dynamic tube sound that transitions to distortion gracefully."
Has anybody here built an amp with these characteristics

[xtian]

"Deep Class A" sounds like "extremely pregnant." A superfluous adjective, no?

[tubeswell]

But how deep is it?

[matt h]

(deleted)

[teemuk]

Well, that went seriously overboard about generic class A amps. Seemed more like an excerpt from a fantasy novel than a serious technical pamphlet, and I'm disturbed by the fact that these sorts of people design and sell amps to us.

[roberto]

When I read this sort of descriptions, I always think that the only deep thing is something that I cannot write here into something else of the customer that you may easily imagine.

[frankdrebin]

My air conditioner is class A+,so what...

[pdf64]

The “low and hot” operating points for audio tubes are suggested by the original engineers of these tubes in the ancient tube manuals as giving a optimally pleasing and musical sonic spectrum with even-order harmonics predominating

I wonder what ancient tube manuals are being referred to?

[ToneMerc]

In pure techincal terms what exactly is "deep class A" and "low and hot"? I did find a reference or two to "deep class A" and came away thinking wow, spin a relatively simple condition and toss out bait designed to catch more fisherman than actual fish.

http://www.lennartlabs.se/projects/leon ... nardo4.htm

http://www.audioasylum.com/forums/bottl ... 93389.html

Not suprprisingly this term " deep class A" appears to be floated around the hi-fi world. In the context of a guitar amplifier; is it a tool to inspire when making music or a device for reproducing recorded music, 60 years of guitar amps with poor efficiency and high THD can't be wrong.


TM

[martin manning]

Hi-Fi hipster. I see he recommends a "directional" guitar cable.

From TM's second link it appears that "Deep Class A" means that the operating point is off-center (to the high-current side). In the example discussed the voltage swing on the low current side (to I=0) is 20% more than the voltage swing on the high current side (to Vg=0).

[Leo_Gnardo]

Mr. Pagano's collection of tattoos is legendary. His actual location IIRC was Fort Lee or Weehawken NJ, and as far as I've heard he split for California some years ago, about ten. I ask my NYC customers and they all say he's gone, long gone.

Low and hot is a good place to have your barbecue. What does BP mean by his "low and hot"? Low voltage, high bias current? OK there's something to that but if it's trend-of-the-moment then why isn't everybody doing it? Damn if I'm going to start setting fixed-bias amps at 100% just because "Blackie's doing it." Lots of other goofy things started to happen to amps after Cesar Diaz "told us to do this and that" in his articles 25-30 years ago.

Perhaps this gives him an excuse to replace power transformers in practically every amp that crosses his workbench. Now THERE'S a way to make a fortune!

If I "dont get it" maybe I need to be stuck with a needle another couple million times. Because that's what makes you smarter, right? Not what I want to think about early Sunday morning.

Bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz. "OOPS!"

[Jana]

http://auroratek.us/uploads/SedonaMUFON2014.pdf

[cbass]

Cold too.
Wait its the other way around

[Cantplay]

To me class A is about clean power.

I like the sound of high gain into asymmetric distortion. Single ended pentode does this with a bunch of compression.

John

[Structo]

But how deep is it?

And how deep does it go?