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Choices, choices, decisions, decisions!
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Old 21st April 2011, 11:21 AM   #31
qusp is offline qusp  Australia
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Originally Posted by rsdio View Post
Thanks for that perspective.

Reading Papa's articles, I have the urge to mix and match ideas from multiple articles rather than build anything exactly as shown. Normally, that would seem like a risky choice, but it seems like you're saying that we're not really going to find any cookbook answers here anyway. In other words, it seems like I might as well piece together my own, unique amp, and see how it turns out. Papa certainly gives plenty of 'extra' information in each article and even hints at a lot of the 'ideas' that (I think) I had.

To summarize: If you want a sure thing, then build one of circuits from a Nelson Pass article. Otherwise, nobody has really quite done the same degree of hand-holding on any of the derivative designs.

If I have the wrong impression - entirely or partially - feel free to clarify.
nope, you got the gist of it just fine and i had the same urge as you, but with a cascoded semisouth circlotron mutant, or an X'd lme49830 chipamp fet hybrid. i'm building the AJX as well with Peter Daniel's boards, but if you feel you have a handle on it enough to mix and match, then go right ahead, all the building blocks are there in the articles. this is how many of these variations have come about in the first place anyway. there comes a point during the huge amount of research needed to do some of these projects that you start having your own ideas and Papa encourages this, thats what its all about. as you say, if you want a sure thing, there are several articles that present such a thing
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Old 21st April 2011, 11:36 AM   #32
qusp is offline qusp  Australia
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i also feel i need to say that this doesnt reflect on Grey at all, he was the first to go out there and publicly release (at least on here) an interpretation of what was a pretty er.... grey area ...sorry at the time and not documented as it was still a patent issue.

that area was the X and power to him he worked through the issues and got it working and from all reports its a great amp, though a bit on the edge of stability, thats why i decided to build the JX, but there are sometimes issues that remain in the design that need to be figured out in situ on a build by build basis to balance the circuit; this is not for the faint of heart. his work on the circlotron is inspiring

Last edited by qusp; 21st April 2011 at 11:42 AM.
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Old 21st April 2011, 12:41 PM   #33
AndrewT is offline AndrewT  Scotland
Join Date: Jul 2004
Location: Scottish Borders
go and download the articles from the Pass sites.
These give you a lot of simple and more complex background to the Pass style of amplification.
Then progress through B1 and F5, both very simple schematics.
Only then try to follow the complexities of aleph & X & AX etc.
Don't read F5x too early. It's a couple of learning stages beyond the F5.
regards Andrew T.
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Old 22nd April 2011, 12:06 PM   #34
rsdio is offline rsdio  United States
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I finished reading all of the Nelson Pass articles, and then ran through them again taking notes on the various technologies.

I think my choice is to build the ZV7-T from Zen Variations 7: More Son of Zen and SuperSymmetry. It's more efficient than Son of Zen, because it doesn't use high power resistors for biasing. Instead, a constant current source is used. Most importantly, it has the matching cross connect of the X amplifiers.

There is also a ZV7-R variation earlier in the article, but the output current-to-voltage is handled by high power resistors. I like the idea of using the transformer as cross-coupled inductors instead.

The A-40 article explains why biasing resistors are the least efficient, and complementary push-pull transistors with a bias voltage source are the most efficient. Unfortunately, the push-pull design is not as simple, and thus less 'Zen.' In between these extremes is the constant DC current source, which keeps the circuit simple. ZV7-R and ZV7-T both hit this middle ground quite well, I think. You'll find designs here on diyAudio that seem to combine super symmetry and the doubly-efficient push-pull output stage, but I think I'd prefer to start with fewer parts.

All of my comments come from someone who has never built any of these amplifiers. I'm just sharing my summary of how I've selecting my preferring entry point into this world. Since you seem to share my affinity for super symmetry, perhaps my brief comments will be useful.

p.s. You should still read all of the articles. Maybe you'll prefer another variation.


Last edited by rsdio; 22nd April 2011 at 12:08 PM.
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