Are Nelson Pass's Greater Accomplishment his High-Powered Designs or the Lower-Powered First Watts?

bazelio

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Let us know what you think of the 30.8.

I think all markets in high end audio are niche. What I should have written is that Pass has the X line and the XA line which appeal to different tastes and may work differently with speaker demands. For a while, they were also selling both the .5 and the .8 series. If you include the integrated amps, and the XS line plus the First Watt stuff, that is a lot of product, not including all of the preamps and phonos. I don't happen to think that Pass Labs products appeal to the mass market. They are just too expensive. I do think that the production runs for the First Watt amps are much smaller than are the runs for the main Pass products, except for possibly the XS line.

It's relative. First Watt is the ideas platform. It caters to DIY. And while some of those ideas have caught on big, Pass is intended to be mainstream (probably the better term as opposed to mass market).

More importantly, cjfrbw I'd be very interested to hear your XA25 vs XA30.8 thoughts. The XA25 reviews are just over the top glowing, and I was considering it when I called Reno, but went with the 30.8 primarily based on the writings of Jack Roberts. As I'm listening this evening as I type, I do think that after 50 hours of on time, it has settled down a bit. But I think what I'm grappling with is the seemingly accentuated extremes. If I have an early complaint it would be that it calls attention to itself instead of simply letting the music flow. It's like that athletic kid you grew up with that wasn't humble about his skills. It really wants to make all bass slam and all treble shimmer, even when seemingly not called for. It's a show off; unabashedly Class A and proud of it. But, wow, the air and space, clarity, scale, textures, micro dynamics, and image precision. And, hey, Mark said no critical listening until Sunday.
 
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cjfrbw

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I don't know if I can be of that much help with the XA25 vs. XA30.8. I would be inclined toward the XA25 on theory and construction (i.e. one pair of devices per channel rather than multiple). However, I heard the two in different rooms with different setups and different speakers. Although I liked them both, there was just no basis for comparison in any meaningful way due to context.
 

BlueFox

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Can’t say what is Nelson Pass greatest accomplishment, but I can say my current stereo gives me an incredible amount of pleasure.
 

caesar

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Not sure why you think this - even JA said the 60.8s were the best amps he's ever heard.

Clearly matching Class A amps to the appropriate speaker is more challenging vs. Class A/B.

Hi Keith,
Interesting thought on extra care to matching Class A vs non-class A amps to speakers. Any specific examples?

And also, personally, I could care less about what the reviewer finds best to suit his taste. I likely don't share the reviewer's taste. Many of those guys mind's are so f*cked up anyways, from all that analytical listening, they need electroshock therapy to get back to baseline. :)

Although Atkinson admitted he really likes Pass, he had the integrity to point out the tradeoffs in getting the Pass vs. other amps, so someone searching can avoid the product, if they don't like that tubby bass. And likewise, although many don't share Valin's "transparency to source"/ frequently analytical taste, his frequent comparisons of an analytical product to a more "as you like it"/ musical product helps draw the contrast in sonic signatures and can inform the purchaser's auditioning process.

On the other hand so many despicable mother fuyers, like "worthless to the audio fans" Robert Harley don't compare at all, and just scream "BEST" every 2 or 3 months, wasting people's time and money. Amazing that a guy like Tom Martin, who should know that the customer experience should come first, allows "worthless to the audio fans" harley screw over several hundred thousand audiophiles that remain in the world.
 

caesar

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I'm hoping that Nelson Pass will lend one of his new SIT3 First Watt amps to the Zu guys for the next California Audio Show, and will also have another Pass XA25 out there somewhere, too.

I thought the XA 30.8 sounded pretty good last year, certainly at that time better than the big brothers all over the show. The XA25 also sounded very good on a more modest system. I have never been able to filter the steely thumbprint out of the larger PASS amps. The Pass XA25 might be the best sounding production PASS ever, being a First Watt concept amp committed to the more rigorous Pass fascia with an additional gain stage. It uses a single pair of hockey puck MOSFETs per channel with very high specs, and goes to 100 watts at 2 ohms.

I would give my EI vote (Experientially Impoverished) to the SIT amps, the unobtanium VFET Pass monster, and my knock off Pass designed DIY VFET as being amongst the best amps ever, even compared to my beloved tubes. They can't really be compared to tubes OR solid state, they are on their own playing field.
However, only the VFET monster would glaze the eyes of the big steel, outlet roasting, forklift loving flash 'n edifice audiophiles.

Thank you. great post, as always.
 

caesar

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Anyone has any thoughts on xa 30 vs xa 25 vs sit2 for easy to drive speakers?
 

bazelio

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Although Atkinson admitted he really likes Pass, he had the integrity to point out the tradeoffs in getting the Pass vs. other amps, so someone searching can avoid the product, if they don't like that tubby bass. And likewise, although many don't share Valin's "transparency to source"/ frequently analytical taste, his frequent comparisons of an analytical product to a more "as you like it"/ musical product helps draw the contrast in sonic signatures and can inform the purchaser's auditioning process.

Atkinson did have issues with 60.5 bass being uncontrolled. Jim Austin, another Stereophile writer, reviewed the 60.8 and addressed the bass issue. He listened to the same tracks Atkinson had used with the older .5 to identify bass control issues, and couldn't find them with the 60.8.

John Atkinson has heard vastly more amplifiers than I have, but in this conclusion I'll echo what he concluded about the XA60.5 monoblock. The Pass Laboratories XA60.8 monoblock is the best amplifier I've heard. What's more, for whatever reason, I didn't hear the single fault he identified in the XA60.5.

Read more at https://www.stereophile.com/content...ck-power-amplifier-page-2#qC0dWtHz20oI1SJj.99
 

PeterA

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It's relative. First Watt is the ideas platform. It caters to DIY. And while some of those ideas have caught on big, Pass is intended to be mainstream (probably the better term as opposed to mass market).

More importantly, cjfrbw I'd be very interested to hear your XA25 vs XA30.8 thoughts. The XA25 reviews are just over the top glowing, and I was considering it when I called Reno, but went with the 30.8 primarily based on the writings of Jack Roberts. As I'm listening this evening as I type, I do think that after 50 hours of on time, it has settled down a bit. But I think what I'm grappling with is the seemingly accentuated extremes. If I have an early complaint it would be that it calls attention to itself instead of simply letting the music flow. It's like that athletic kid you grew up with that wasn't humble about his skills. It really wants to make all bass slam and all treble shimmer, even when seemingly not called for. It's a show off; unabashedly Class A and proud of it. But, wow, the air and space, clarity, scale, textures, micro dynamics, and image precision. And, hey, Mark said no critical listening until Sunday.

Things may change on Sunday after more break in, but the amp may be revealing some issues with set up or upstream components. Perhaps the transparency of your amp/speaker combination is putting a spotlight on the quality of your source component. Is this "attention to itself" across formats and recordings?
 

caesar

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Atkinson did have issues with 60.5 bass being uncontrolled. Jim Austin, another Stereophile writer, reviewed the 60.8 and addressed the bass issue. He listened to the same tracks Atkinson had used with the older .5 to identify bass control issues, and couldn't find them with the 60.8.

John Atkinson has heard vastly more amplifiers than I have, but in this conclusion I'll echo what he concluded about the XA60.5 monoblock. The Pass Laboratories XA60.8 monoblock is the best amplifier I've heard. What's more, for whatever reason, I didn't hear the single fault he identified in the XA60.5.

Read more at https://www.stereophile.com/content...ck-power-amplifier-page-2#qC0dWtHz20oI1SJj.99

Thank you so much! I don't have to time to chase it down now, but do you know the speakers each of the guys used in the review, as guys like Keith and CJFRBW strongly suggest that those negatives come out in hard to drive speakers. Thanks
 

bazelio

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Things may change on Sunday after more break in, but the amp may be revealing some issues with set up or upstream components. Perhaps the transparency of your amp/speaker combination is putting a spotlight on the quality of your source component. Is this "attention to itself" across formats and recordings?

I noticed last night (at about the 50 hour burn-in point) that the sound had opened up. Layering and air, which was already good, was now noticeably better. I think most amps perform a spotlighting function. SET amps so often spotlight the midrange. From a SS Class A topology, one can also reasonably predict certain results, as Keith has mentioned. We know Class A (Pass or otherwise) to be not strictly transparent. And truth be told, I was expecting the 30.8 to be a bit warmer than it is and am pleasantly surprised in that regard. But the Class A Pass does seem to be highlighting dynamics - which makes it a very "fun" listen even if not strictly accurate.

Elsewhere in the chain, my first thought might be the cartridge which is also a dynamic performer. What do you think? Kuzma StabiM, 4-point, Transfiguration Proteus, EAR 324, Passive Slagle autoformer pre, Pass 30.8 -> Martens. I'd say the Pass, other than highlighting the extremes, might have just a touch of dryness through the midrange. I was wondering last night how one of the Zyx Premium series carts might integrate in to this chain. My other thought is to leave well enough alone and try Class AB, like a Dart 108, next. That would very likely address the spotlighting and mids.
 

bazelio

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Thank you so much! I don't have to time to chase it down now, but do you know the speakers each of the guys used in the review, as guys like Keith and CJFRBW strongly suggest that those negatives come out in hard to drive speakers. Thanks

John Atkinson may have called the XA60.5 the best-sounding amplifier he'd ever used, but he did report a flaw. With the XA60.5s driving Wilson Audio Specialties' Alexia and Vivid Audio's Giya G3 speakers, he found the bass under-controlled. With a pair of 60W amps, this is understandable—either speaker will challenge an amplifier, the Wilson more so.

----

This isn't a perfect test, as I'm not using the same speakers JA used. The Alta Titanium Hestia's resolution in the bass may not be as good, and we won't know how hard they are to drive until JA measures them for the forthcoming review.

----

As I wrote before, it wasn't a perfect test. It could be that these speakers are less demanding, or less resolving than the ones JA was using. Room resonance could be limiting the system's resolving ability. Or maybe the extra metal in the XA60.8 makes all the difference. Whatever the reason, I didn't hear what JA heard with the XA60.5s.
 

cjfrbw

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I don't know why a push pull class A amplifier would have any more problem than a class AB in speaker matching.

Class A push pull amplifiers are typically defined by their 'Class A' envelope, while often producing much higher power as power demands tilts them into class AB, often exceeding their nominal Class A spec by as much as 4-6db in RMS, and then again another several db above that in transient overhead.

The Accuphase 20v model that is nominally 20 watts class A:

"the more than ample performance of the
A-20V: 1 ohm: 156 watts, 2 ohms: 126 watts, 4 ohms: 85 watts, 8 ohms: 50 watts."

The Pass XA30.8 is not a "low powered" amp. It is an amp that is low-spec'd at it's class A envelope. It likely produces more than adequate transient power in class AB above 150 watts.

The Stereophile measurements of Pass XA25 show it as performing much higher than specs: "Pass Labs specifies the XA25's output power as 25Wpc into 8 ohms and 50Wpc into 4 ohms (both equivalent to 14dBW). However, as you can see in figs. 4 and 5, the amplifier exceeded its specified power output at the clipping point, which we define as when the THD+noise equals 1%. At that THD+N percentage the XA25 delivered 80Wpc into 8 ohms (19dBW) and 130Wpc into 4 ohms (18.1dBW).
"
 
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bazelio

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I don't know why a push pull class A amplifier would have any more problem than a class AB in speaker matching.

Class A push pull amplifiers are typically defined by their 'Class A' envelope, while often producing much higher power as power demands tilts them into class AB, often exceeding their nominal Class A spec by as much as 5-6db in RMS, and then again another several db above that in transient overhead.

The Accuphase 20v model that is nominally 20 watts class A:

"the more than ample performance of the
A-20V: 1 ohm: 156 watts, 2 ohms: 126 watts, 4 ohms: 85 watts, 8 ohms: 50 watts."

The Pass XA30.8 is not a "low powered" amp. It is an amp that is low-spec'd at it's class A envelope. It likely produces more than adequate transient power in class AB up to 200 watts.

The Stereophile measurements of Pass XA25 show it as performing much higher than specs: "Pass Labs specifies the XA25's output power as 25Wpc into 8 ohms and 50Wpc into 4 ohms (both equivalent to 14dBW). However, as you can see in figs. 4 and 5, the amplifier exceeded its specified power output at the clipping point, which we define as when the THD+noise equals 1%. At that THD+N percentage the XA25 delivered 80Wpc into 8 ohms (19dBW) and 130Wpc into 4 ohms (18.1dBW).
"

To some folks, speakers like Wilsons sound a tad boomy. Paired with the accentuated bass slam of the XA .8 that I'm hearing, the pairing might not be to everyone's liking. As an example.

BTW, other than a little extra power, how do you think the XA25 differentiates itself versus the FW F7? They're awfully similar, which makes the X25 a bit of an oddball Pass Labs product IMO. One power rating only, etc. Feels like a glorified FW amp... (I know that's where it originated)

PS - I noticed you're in Pleasanton. I'm not far....
 

cjfrbw

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I'm not sure the circuit specifics of the XA25 have been revealed yet, except for the massive hockey puck MOSFET output devices, and the fact that there is an additional gain stage in the XA25 compared to FW products, which are limited to one or two gain stages. The PASS LABS stuff typically has heavier build, more protection circuits etc. than FW stuff. The F7 I guess uses more standard MOSFETs, and he broke the mold on that one by adding back some positive global feedback (usually a no-no in modern amp design) to give it some personality favored by his listening panel.

Pass himself used to build the earlier FW models, then employed nephews under his direction, and now I guess he carefully oversees a separate area of the large PASS labs production facility due to demand for FW products. However, the FW stuff, even considering their low production runs, have almost vanishingly low warranty issues. For all their simplicity, the FW are intended to be hand built artisan products vs. factory production models.

Calling the XA25 a glorified FW amp is actually a compliment.

I have spent a bit of time on the DIY sites, because I learn more there than the usual audiophile 'poetry and possession' cant you wade through on a lot of sites. The DIY guys also seem to have more fun and joy in their hobby, and they have listening skills that are every bit as refined as mainstream audiophiles, not to mention the technical skills.

If you are close to PLSNTN, and want to stop by for a listening session some time on my Frankenstein system, let me know. I am there a couple of days a week. At the present time it is hosting the vintage VFET amps. I'll be going over the CAS 2018 in a couple of weeks, either Friday or Saturday, if you want some company to go to that. CAS typically has LOTS of PASS LABS stuff on many different kinds of systems.
 
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cjfrbw

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Anyone has any thoughts on xa 30 vs xa 25 vs sit2 for easy to drive speakers?

I think I can answer this question in the usual IMHO way, having heard the Pass XA25 in two separate installations at the California Audio Show 2018 today.

The XA25 is an amplifier that you can pay full retail for, and still believe that you stole it from the factory, it's that good.

The XA30.8 is good, too, but for the things I like, the XA25 is better. I heard the XA30.8 last year on the same Zu speakers, I believe.

XA25 has NO SOLID STATE signature that I can hear, in the traditional way I think of solid state, even with a complete SS chain (also PASS). When solid state in the past has tried to sound mellow and tube-ey, it becomes sort of golden and diffuse. XA25 isn't like that at all.

XA25 is very high, wide, deep, and dimensional in soundstage. It is very slightly on the dark side of things, but still extremely articulate with a bodied tone and texture. It also does something that my First Watt M2 does, i.e., it has for want of a better expression lightening flashes of brilliance where the whole soundstage dimensionally lights up, kind of like a hand clap waking you up. It is organic and wholistic without losing resolution in any of the frequencies. Even though the toplogies of the First Watt M2 and the A25 are different, they seem to share that wholistic (tilting towards organic) presentation. A25 has more than a bit of spooky quality.

It is a top tier amp by anybody's standard in it's rendering, and I think it is the best PASS amp I have heard, even compared to its big brothers, or at least it has the characteristics that I like more.

It made the Zu speakers sound as good as I ever remember them sounding over the years, even compared the First Watt SIT amps (masters of black spaces and separation).

I don't think you can compare XA25 with either solid state or tubes, though if you twisted my nuts, I would put it on the tube side of things. It really is in a category of it's own.
 
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