A question regarding Ono

[Peter Daniel]

I am about to built my second version of Ono phono stage. Just today I stumbled across Stereophile Recommended Componenets and this is what they write about Xono:

For MF, listening to great recordings through the Pass Labs Xono became "an overwhelming experience". While retaining the same basic design, the 76dB-gain Xono excels in areas in which its predecessor, the Aleph Ono, faltered. The Ono's soft bass is now firm, and a threadbare midrange has been fleshed out nicely. "One of the most accomplished-sounding phono stages" MF had ever heard. It's ultra-low noise floor, transparency, resolution of detail, ambience retrival, and tonal neutrality were "absolutely Class A. (Vol.25No1)

All that sounds great, especially when it comes from Michael Fremer. So my question is, if it's not a secret, what mainly brought that transformation to the original Ono design? I was already searching for alternative choices, but after reading this, I can't hold myself from trying an "improved" version of Ono

[Nelson Pass]

It's hard to say what specific item might have influenced
the review. If I knew, it would still be our policy to hold
schematic details until the model is superceded.

[Peter Daniel]

In that case I will follow an official guideline and also experiment on my own

The Xono is based on the design pioneered in the Aleph Ono. The basic Ono design has not changed but been extend and refined. The separate power supply combined with the additional filtering and dual mono power supply design contribute to the lower noise floor and sonic improvements. The main circuit board layout has been completely revised to reduce noise, shorten the signal path and reduce the length of connecting wires. Sonically critical parts have been optimized and upgraded through continued extensive listening tests.

[jcarr]

Peter:

Caveat: I normally pick my componentry from the beginning of the design process for performance characteristics and physical constructions that I think are "correct", and I also design circuitry in ways that (I hope) reduce the influence of componentry. Perhaps, therefore, my designs are less sensitive to componentry choices than other designs.

With that warning in mind, in my own experience (on my own circuits), circuitry operating points, board layout (including the use of additional layers) and harness design have a substantially greater influence on performance (both measured and perceived) than choice among nominally similar componentry. Not even close.

Now this doesn't mean that I believe that the measured and sonic effects of componentry should be pooh-poohed, or you won't get a big difference if you do something like changing the feedback resistor from a bulk-metal foil to a carbon-composition type in a humid environment.

But I do think that it is possible to study the schematic and board layout and predict what the appropriate componentry should be for top-notch performance and perceived sonics. Normally my initial componentry choices survive intact to the end of the design process.

>The separate power supply combined with the additional filtering and dual mono power supply design contribute to the lower noise floor and sonic improvements.<

Separate dual mono power supplies should be sonically worthwhile, and will probably also give you better crosstalk and channel separation measurements.

>Sonically critical parts have been optimized and upgraded through continued extensive listening tests.<

Sometimes I am surprised by the results of listening test regarding the final choice of componentry, but in my case, this normally doesn't happen. I do listening tests all the time, yes, but in retrospect they usually tell me what I *shouldn't* do (or use), rather than what I should.

BTW, Nelson, kudos on the Stereo Sound award for the Rushmore. Congratulations!

regards, jonathan carr

[Peter Daniel]

I will not comment on this directly, but here's an interesting observation I made, while reading the latest Stereophile Recommended Components section:

ML 38 preamp, when it came out, was regarded by JA as a state of the art and soon became his reference preamp. Later, Madrigal upgraded the circuit board to Teflon based material with two additional layers. Also, 15 passive parts per channel were upgraded (to what it seem Vishay resistors and one teflon cap). Otherwise the componentry and layout remained unchanged. Now this preamp became the reference for JA and he was raving how much better it is over the previous one.

I believe that Madrigal team claimed at that time that only the parts which brought audible difference were substituted and it was all based on listening tests.

Now, we read that in version 380S of the preamp, the circuit, pcb material, and remote-controlled volume control are the same as those in earlier no.38S preamp, the substitution of 106 passive components left JA searching for words: "how do you describe something that's superficially identical to your reference, but better?..."

[jcarr]

Peter:

Sounds very familiar. And since the first time that I tried Vishays and Black Gates was (I believe) in 1980, it also feels rather nostalgic.

Yes, I've had similar experiences when changing passive components. And as you quoted, big difference. But after a time, you realize that sonic change is not always sonic improvement, and you will also begin to understand what types of component constructions and characteristics will work best for any given location in your design. It will start to feel as though the design itself dictates what components it needs, and those choices should be pretty much spot-on in subsequent listening tests. And if those choices sometimes include low TCR low-inductance resistors or teflon capacitors, so be it.

For its part, a top-notch layout (board/harness) will reduce the degree of phase compensation and additional stability measures that you need, markedly drop distortion and may also improve the noise floor. All of which have the potential to improve the sound big-time.

I've never seen a layout which couldn't be improved on. It's a field that you can study and work on for years and years, and still only scratch the surface. And as I have said on numerous occasions previously, the board and harness layout *is* part of the schematic design.

True, layout design may not appear as flashy nor worthy of a high price-tag as exotic componentry. But over the years, I've concluded that time spent studying board design means rather more at the end of the day than time spent agonizing over component choice.

OTOH, I've also done things like having custom capacitors, resistors, semiconductors, transformers and what-not manufactured to my design and/or specifications. Undoubtedly studying and experimenting with componetry also has its points.

If you have the time and money, tackle both.

regards, jonathan carr

[Peter Daniel]

Jonathan,

It is very true what you are saying. The more I experiment with exotic components, the more I understand that in a specific circuit and to achieve a specific sound, there isn't too many combinations of parts and not *any* exotic part fits the bill. It takes hours of carefull listening and comparing and only a certain combination of parts brings the best result. Sometimes the most exotic or expensive parts are simply no good and sound out of place.

Whenever I think about the design, I always try such layout that the actual requirement for a harness and wiring is minimized, and the connection points are rather dictated by a function and not the form.

What would you recommend for the RIAA caps to start with? Some people claim that silver mica is best for that, but I don't believe it. Madrigal is using Wima, but there are better choices than that. I was using MIT RTX, but they seem to be too big for such sensitive circuit. Boulder changed their site, and I don't see it anymore

[macka]

Peter,

You may wish to consider the North Creek capacitors.

In a previous thread Mr Pass let slip he has been secretly taste testing some of these and found the lesser expensive variety impressive.

On the subject of improvements it must be fun being a member of the Passlabs crew. That is having the rare privilege of taking gear home, evaluating it and being part of the tweeking & blending process.

Being part of the best of the best I mean.

macka

[Nelson Pass]

Originally posted by macka
On the subject of improvements it must be fun being a member of the Passlabs crew. That is having the rare privilege of taking gear home, evaluating it and being part of the tweeking & blending process. Being part of the best of the best I mean.

That's true, but it's still work.

[macka]

And if you enjoy your work it can also be fun.

I recall a biographical note in the Pearl article sums up the definition of work rather nicely.

Fifteen years or so ago Pass placed an advertisement in the back of Audio Amateur which said,

Assistant Wanted. High Pay, No Work, All Glory

(Wayne is the guy who got the job.)

But we are all aware Mr Pass is supported by a highly dedicated team who work tirelessly to sustain the success of Passlabs.

Macka