Hello chorus, Pass Labs admittedly and intentionally adds some even order harmonic distortion to all their amp designs. This is commonly known to be perceived by humans as a euphonic overall sound quality similar to tube amps, which many devoted Pass fans and others desire and enjoy. There are many other amp designers of amps in this expensive price range who restrain themselves from doing this for the sake of accuracy.
My local dealer agrees with noble 1002 with the exception of the Xa-25. He says it sounds like no other Pass amp. It's totally neutral. I agree. If you haven't heard one please don't pass on disinformation like the above.
Pass Labs admittedly and intentionally adds some even order harmonic
distortion to all their amp designs. This is commonly known to be
perceived by humans as a euphonic overall sound quality similar to tube
amps, which many devoted Pass fans and others desire and enjoy.
There are many other amp designers of amps in this expensive price
range who restrain themselves from doing this for the sake of accuracy.
I should point something out here. The big difference between tubes and transistors is that tubes tend to sound smoother, with greater actual detail rather than brightness masquerading as detail.
But tubes have measurably greater distortion- so how is this possible?
The answer has something to do with the ear's masking principle; that is where a louder sound can mask the presence of a quieter sound.
It also has to do with how the ear perceives distortion, and in this case I'm talking about distortion where the amplifier is not being overloaded. The ear interprets the 2nd and 3rd harmonics as 'body', 'warmth', 'fullness' and the like, all terms to describe their presence. If these harmonics are present in sufficient quantity, they will mask the presence of the higher orders. Since tube amps generally have more of the lower orders (2nd, 3rd and 4th) than solid state amps, the result is that the higher orders are masked and so tubes sound smoother even though they have greater higher ordered harmonic content than solid state.
So solid state tends to sound brighter and harsher (harder) than tubes because the ear interprets the higher orders in this manner, simply on account of the fact that the higher ordered harmonics (to which the ear is keenly sensitive as it uses them to gauge sound pressure) are exposed.
But there is more, and this bit is really fascinating. The lower orders, if in sufficient quantity, also contribute to soundstage width and depth, as well as lower level detail! This is why tube amps tend to have a wider and deeper soundstage than solid state. Oddly, this is not an exaggeration, but in order to understand that this is so it is helpful to have master tapes or files and also to have been present at the recording to know how it is supposed to sound.
The bottom line is this: unless the amplifier has **no** distortion and by that I really mean no distortion at all and not just vanishingly low, the inclusion of a bit of 2nd and 3rd in sufficient quantity can actually result in the amplifier sounding more 'neutral' to the human ear. Again, this is a topic that deserves more research, but this phenomena has been known for quite some time.
So its going a bit out on a limb to use the word 'accuracy' as in the comment below.
There are many other amp designers of amps in this expensive price
range who restrain themselves from doing this for the sake of accuracy
Put another way, if the amplifier designer is aware of how the human hearing perceptual rules work, and is pragmatic about the simple fact that building an amplifier that truly has no distortion is impossible, then the next best thing to do is to include some of the lower harmonics for the perceived benefit they bring, even though it might look bad on the spec sheet. In this way its easy to show that the spec sheets are a good example of the Emperor's New Clothes, as for the most part they ignore human hearing perceptual rules as they have been ascertained in the last 40 years.
Nelson Pass seems to have sorted this out. He is one of the few solid state designers to have done so, and no surprise, his amps sound more 'natural', 'neutral' and musical (IMO) than his competition with lower distortion as a result.
I’m on the "NeverPass" camp. It’s not ideological, it’s not personal (Nelson Pass is a fine gentleman), it’s not anything about the quality of the gear. I just really find the sound scratchy or weak. I assume, without investigation, that the euphonic distortion Pass adds and which his fans love and which Stereophile often measures, is exactly what I do not like. This is an IPA vs. Belgian White discussion though, there’s no right or wrong, but for my wallet, no, never would I buy, nor would I put a Belgian White in my mouth deliberately. I’m in the minority, and happy to let Pass fans love the products.
I also wonder based on some of Pass' writing about proper matching of amp output impedance to woofers if he isn't targetting a specific type of big-woofer speaker like Tannoy and Klipsch folded horns. Neither of which I listen to. Not a criticism, but a question of intended matching.
Amps I like a lot:
Luxman Arcam Ayre D’Agostino
Amps I don’t like as much, but still more than Pass:
Parasound ARC
Amps I’d like to hear more of to make a better view:
Right, and this is the basis of MP3 compression, among other things. Why do you think the masking principle benefits tubes??
I thought I had explained that enough, but nutshell explanations can be tricky. Essentially though the tubes have enough 2nd and 3rd harmonic distortion that those harmonics are able to mask the presence of the higher orders. So they **sound** to the human ear as if the higher orders are absent altogether. That is why they sound smoother.
erik_squires; You seem to have gone off the deep end lately. You used to be a reasonably affable and knowledgeable bloke and now this? Do you really not comprehend the difference between MP3's shortcomings (and all of digital's) for the totally separate and distinct concept that Ralph is discussing? Are harmonic orders and truncated bits the same thing to your mind? To mine, there is one connection between Ralphs's post and digital and that is the limitations of modern measurements. Time and time again John Atkinson would measure a DAC (Benchmark being a prime example) or an amp (Benchmark again is a good example) and declare the measurements to be beyond reproach and often the reviewer coincidentally gave a rave review, but the buying public has disagreed. Certain highly esteemed writers/reviewers at S'Phile even disagreed. That is the only connection between Ralph's point and explanation and digital/MP3.
And does your post above mean that you have only heard 8 brands of amplifier in your lifetime? Implicitly equating the performance of ARC and Parasound is another gaffer.
You used to be a reasonably affable and knowledgeable bloke and now this?
@fsonicsmith
It is clear from your starting sentence you are confusing me with some one else. I won't be controlled by your disappointment, nor am I obliged to answer all of your obviously malformed inferences.
Do you really not comprehend the difference between MP3's shortcomings
(and all of digital's) for the totally separate and distinct concept
that Ralph is discussing?
I've never made any such equation. I mentioned that Ralph was using a concept known to me (please read the entire Wikipedia article here:
) and to ask him to clarify the leap he made which I could not follow. I did so in a respectful manner, and gave him the opportunity to come back and illustrate his point so I could get it. Fortunately for me, he did:
@atmashpere
Essentially though the tubes have enough 2nd and 3rd harmonic distortion
that those harmonics are able to mask the presence of the higher
orders. So they **sound** to the human ear as if the higher orders are
absent altogether. That is why they sound smoother.
Oh, my bad. I thought you were saying that the masking some how improved resolution. You are saying that masking reduces the perception of distortion. I was confused because earlier you mentioned that tubes have more detail, but the masking of distortion is unrelated to the perception of detail.
Thank you for the clarification.
Masking though, AFAIK has to do with closely spaced frequencies. Hard to mask higher order distortion, isn't it?
BTW, I like tubes a great deal. :) I'm not attacking them I just want to make sure I understand the arguments.
The explanations provided by Ralph above are exactly what I have been reading about and find so interesting. Being afflicted with both Tinnitus and Hyperacusis along with a measured 10k max hearing level, I am very sensitive to harsh, forward, bright sound. Over 85db is uncomfortable and when overexposed I require some time to pass before I want to hear any music even at lower levels. So that is me. Everyone hears things differently so judge not lest ye be judged. I pass my finding as they relate to me.
My goal for is for music to move me, involve me, engage me. "Magic" is the best term I think.
If "Neutral" and "Accurate" are your goals, the Lejonklou house sound may be your ticket. Fredrik has a special Nothing Extra method of building amps that allows you to hear lyrics you only guessed at before.
Sometimes I wonder if all the terminology in use today-soundstage, airy, open, dark, etc was developed in an effort to classify sound that was actually unmoving thus required further examination? If sound does something to your brain that feels great then enjoyment is achieved. Enough?
If sound does something to your brain that feels great then enjoyment is achieved. Enough?
@chorus
Yes. :-) The only judge of what you should spend your money on is ultimately the buyer. Neither I nor an oscilloscope nor countless reviewers have any right to interfere in that process.
Still, this is a discussion forum, and when asked to think about what we like and why we like it the technical differences in gear is a lot of fun to discuss.
Just like beer. We can talk about the brewing process and the hops added, which is fascinating, but ultimately the reason you end up in detox is up to you.
I’m also, often, reminded how malleable our tastes are. I’ve been drinking this new tequila (Tres Amigos, organic, silver) which a very nice bartender recommended to me. At first I thought it tasted watery. My taste buds kept searching for the agave and earthy notes which are not there. Now that is gone and it tastes very smooth.
We are not automatons with precise, and unchanging hearing or tastes. We have all taken different paths to get to this forum and we’ll go on different paths when we leave. Lets relish the diversity, and be grateful for those willing to share their experience and education with us openly.
I was confused because earlier you mentioned that tubes have more
detail, but the masking of distortion is unrelated to the perception of
detail.
Thank you for the clarification.
Masking though, AFAIK has to do with closely spaced frequencies. Hard to mask higher order distortion, isn't it?
BTW, I like tubes a great deal. :) I'm not attacking them I just want to make sure I understand the arguments.
@erik_squires To be clear I didn't feel you were making any sort of attack! Asking for clarification is not an attack, and I welcome it.
Masking is a tricky thing but AFAIK doesn't have to involve closely spaced frequencies; if they are not closely spaced the ability to pick out the lower level sound(s) is better. This is fairly easy to experience. One example of this is our ability to pick out information when there is something like white noise in the foreground; analog signals can have noise but we can pick out signals that are a good 10dB below the noise floor! (I suspect this has something to do with the fact that wind and water sounds are very similar; so this could be a survival issue)
It appears that the ability to pick out signals in the noise floor relates directly to amplifier design. Amps with zero feedback tend to have a noise floor that involves a fairly natural 'white noise' hiss; amps that run feedback tend to have a noise floor that consists of inharmonic information and intermodulations, into which it **seems** that the ear cannot penetrate as it can a natural noise floor. This might explain why amps without feedback can often seem as if they have more low level detail. This is an area that I also feel needs more research (one exception to this is if the amp with feedback has sufficient gain bandwidth product such that it is stable with over 35dB feedback; such amps are quite rare).
At any rate, I did say that tubes have more detail, and that they manage this without being bright. However I wasn't suggesting that masking distortion was the reason. I was instead suggesting that the presence in the correct quantity of 2nd and 3rd harmonic content somehow contributes to the ear's ability to pick out natural detail in the recording (including soundstage information). While this is documented, exactly how this occurs is an unknown (AFAIK) and something which I find very interesting.
I already know you are comfortable with having a civil discussion when it comes to nuanced technical topics. My disclaimer (that I like tubes) was meant for those who read only the convenient parts.
I have owned a couple of a Pass amps (including an INT-60, which a friend now has) and I still own a couple of First Watt amps. I have also built two Amp Camp Amps (ACA), which are designed by Nelson Pass. I respect Mr. Pass for his “different/subjective” approach. The reason is didn’t keep the Pass amps was due to size and heat, they are big and hot. Large Class A designs just don’t work well for me. Nothing against the sound.
With that said, I have found a few amps that have a similar sound to Pass that I prefer:
Nagra Classic INT
Naim SuperNAIT
Gryphon Diablo 300
The Nagra is refined with lots of air and ambient texture.
The Naim is smooth, organic and lush.
The Gryphon is dynamic, fast and detailed. This amp, like the Pass, is big and hot, and those side fins can bite when it is moved.
The speakers and room, as always, play an extremely important roll.
And to mention, they can drive any hard to drive speaker to it’s best, especially when the speaker loads dip below <4ohms, unlike anything else mentioned so far on this thread, except the D'Agostino.
My speakers are older Tannoy FSMs. Sideways picture in my logo. Circa 1985-90. Rated 94 sensitivity. Run at 4 ohm.
Room is midsized and treated well.
I am not sure if those three models can be had used at my $5k budget.
Pretend we are on House Hunters. Which one can we eliminate??? The Nagra can go as I buy no Swiss products. Personal thing. Naim is a possible. The Supernait gets good ink. Love to hear it in my system.
The Luxman integrated amps (mentioned by @erik_squires) are wonderful sounding, especially if you want a less harsh, less fatiguing sound for your tinnitus. Have you considered a tube amp?
@chorus Not to be a Pass pusher, but you may also consider some first watt offerings. Nelson tests all of his products on Tannoys and as such you should be able to find an ideal match from the lineup.
In various systems over the years I've tried a number of amplifiers (Atmasphere M60s, Lyngdorf TDAI3400, Coincident Frankenstein 300b monoblocks, Classe INT150, Pass Labs XA30.5, X250.5, XA25, First Watt SIT2, and DIY First Watt SIT3 and F4 monoblocks).
I've always enjoyed the Pass products, but did not end up buying the XA25 I demoed, sticking with my underpowered Coincident Franks before ending up with First Watt F4 monoblocks (all with Coincident PRE speakers, see my system page).
I don't quite have enough experience to be sure that this is the reason, but both the Coincident 300b Frankensteins and the First Watt F4s are dominated by 3rd order harmonics, while the XA25 is dominated by the 2nd (and all three have low levels of higher order harmonics). My guess is that my ears are sensitive to the balance between the 2nd and 3rd, and prefer amps that are 3rd harmonic dominated.
Given everything that you've stated, it might be worth trying out a First Watt F4. Since you don't listen loudly, you probably will be ok with a zero gain amp. My system can also be bright and I'm also very sensitive to forward amplifiers, and find the F4 to be refined and smooth on top. Unfortunately they don't make new units, but the price will be right if you can find one used (or have someone DIY one for you, they sell official boards at the DIYAudio store).
I owned the Pass XA25 for several months and had a chance to compare it against some other amps. The original question asks which, if any, do you "prefer" over it. Any answer to that question is going to depend on at least two variables: your personal tastes and your speakers. Amps will sound different when driving different loads. In the end I preferred the Parasound Halo amps. In my case it was the A21. I auditioned several amps and what I heard always boiled down to a judgment between transparency vs dynamics. Yes, the Pass was more transparent than the Parasound. However, the Parasound provided considerably greater punch and rhythmic drive and offered decent musicality to boot. In the end, this simply reflected my personal taste, and I might have felt differently had I been using different speakers. The impedance of the speakers I use drops down to about 2.8 ohms in the low end and requires an amp with a really beefy power supply and a lot of current to sound good. Interestingly, purely in terms of musicality the amp I liked the most was the Yamaha A-S2100 integrated. However, it sounded even more anemic than the Pass in terms of dynamic drive, not that the Pass sounded anemic. These are all relative assessments.
I started on the First Watt path. Then I saw an review of the Cheviots in which both a SIT3 and an XA25 were used. He said the SQ jumped very noticeably with the XA25. That's a pretty close comparison to my system. Also the thing which got me interested in Class A was after buying a used pair of Pass diy monoblocks. 7 wpc. They are not bad for the $350 I spent. The F4's are certainly much better than the set I have. I could save a bundle buying the diy pack if still offered. Problem is at this stage I am more looking for SQ than a cheaper out. I have a limit of $5k for this. Thanks again the fine ideas.
Have any of you compare the pass amp with Bedini 25/25 100/100 ? For 1/3 prices of pass amp , I’m happy with my Bedini , I also have Yamaha as2100 , mx1 and they are not far behind but I prefer Bedini
Chorus, I recommend that you get your hands on a new or used Sugden A21SE class A signature single ended. I’m using it on my Tannoys and it sounds wonderful. $3250 new....30 watts into 8 ohms, 40 into 4 ohms....no bells, no whistles, just 5 line inputs, a record out, and a remote......my Tannoys are the Legacy Eaton's....
In my opinion, the question posed by the OP and the responses that followed are all presented in the absence of the central question of what speakers will be partnered with the proposed amplifiers. Without this information, most if not all the recommendations boil down to personal preferences.
IMO the First Watt amps are nothing special. I have heard four of the upgrades so far. I built a FW amp using better parts and point-to-point wiring that was much better in every area. Cost me about $500 in parts, etc.
As for Luxman products (which I like BTW) I met the Luxman rep a month ago. He was trying to tell me that EI transformers were quieter than toroidals. That goes against anything I ever learned. He told me after many years of research this was their findings. So what does that mean? Well nothing if you prefer the sound of their products.
As for the OP question, the amps that I build are what I prefer but knowing Pass Labs products the one you are referring to is an excellent amp when I had it in my system.
1. @tomlhuffman is completely correct that every outcome is totally system dependent. This issue is routinely ignored on the forum, which is to some extent the nature of the beast... but really, it's unfortunate that every person doesn't list their system along with their post (or in their associated system page).
2. @chorus, I'd just like to note that I also was more interested in SQ than value. Once I bought my Coincident Pure Reference Extreme speakers, I went on an amp search that involved Atmasphere M60s, Lyngdorf TDAI3400, Coincident Frankenstein 300b monoblocks, Pass Labs XA25, and DIY First Watt SIT3 and F4 monoblocks. I originally built the F4 monoblocks as a booster amp to pair with the Coincident Frankenstein 300bs in order to improve bass performance, but ended up preferring them to all the other amps listed. They also happened to be the cheapest. I was happy about that, but it had no impact on my decision, however.
3. @kalali, I totally agree, and it's a shame how often this happens on Agon. Fortunately, at some point during the discussion it did come out that the OP has Tannoys, which is the only reason I posted about alternative Pass products.
@bigkidz Is there anyway I could get some pictures of your P-T-P version of the First Watt amp? I've been considering a top quality part upgrade to my F4s and wouldn't mind also eliminating the circuit board either. Would be really useful to see a template in making the transition.
I will say that building separate power supplies for each channel in the F4 made a huge difference in the sound. Don't think I'll ever go to a shared power supply again.
Have any of you compare the pass amp with Bedini 25/25 100/100 ? For 1/3 prices of pass amp , I’m happy with my Bedini
@atl4love Although we've not done any comparisons, we have had the Bedini in our shop (one was recently in here for repair) and it is one of the better solid state amps we've heard. If you like the amp though, seriously consider getting the filter capacitors in the power supply replaced- that was part of the problem with the one we had here.
@atmasphere thank for your recommendation about the cap replace ! To my ear I have a n.e.w amp one of pass labs aleph j designs 25 watts per channel and I have compare both with Bedini 100/100 the pass dried at top end and the Bedini was liquid and extant highs with punchy low , I would like to compare later pass production but don’t have the chance to audition any of them !
Does anybody on this thread have experience with Spectral?
Very limited. Got to hear it once at Goodwin's High End in Waltham, MA driving Avalon acoustics with mostly or all ceramic drivers (long time ago).
Sharp as hell sounding, razor like transients. Not really compelled to listen to it. The presentation (amp + speakers) was the most sterile but also compressed. The transients were sharp, but the music didn't seem to open up.
This was a 30 minute listening session decades ago. Please listen for yourself and take the limited experience I had into account.
Audioguy-Re the Sugden idea. I had the Masterclass IA 4 in the system last week as a test thinking it should be pretty good. Oddly it did nothing special for the sound. I was surprised. Just not a great match for some reason. Cal- Re the First Watt F4s Monoblocks. I wonder if these worked best with your speakers as your speakers are a harder to drive and the F4s have more power than the XA25?
@atmasphere, interesting and beautiful theory /hypothesis on harmonic orders. it is not easy to imagine how it works in practice. how different harmonic orders are related in phase/time, why their combination should lead to a soft pleasing sound? how many amps with 0 distortion did you see, what you mean when you refer to an amp without any distortion? and what if the distortion is too small, say .001? would then still a several harmonic order sound with distortion be better, by the way, how many harmonic orders give tube amps (all of them the same number)?
i was a tube fun for 15 year used only tube amps. once i tried a class ab/a amp i was indeed pleased and even released with a clean clear sound that it produced. if your auditioning experience is based on a sound with distortion, you are merely in a wrong musical world. it is a personal matter whether you like it or not. in painting, i personally like impressionism the most, because i like to see the world in this alternative way. but ii think sound and music is something different, one naturally prefers a natural uncolored sound that come from musical instruments. if there is a luck of some details and sound is not clean, you do not really perceive what the artists wished to express.
i personally do not like colored sound that produce many expensive and extremely expensive amps (and also speakers). they just to not sound right for me. currently, i am pleased with Cherry Megaschino class D amp which sounds very neutral, detailed and clean, is much smaller and consumes much less energy.
@atmasphere, interesting and beautiful theory /hypothesis on
harmonic orders. it is not easy to imagine how it works in practice. how
different harmonic orders are related in phase/time, why their
combination should lead to a soft pleasing sound? how many amps with 0
distortion did you see, what you mean when you refer to an amp without
any distortion? and what if the distortion is too small, say .001? would
then still a several harmonic order sound with distortion be better, by
the way, how many harmonic orders give tube amps (all of them the same
number)?
i was a tube fun for 15 year used only tube amps. once i
tried a class ab/a amp i was indeed pleased and even released with a
clean clear sound that it produced. if your auditioning experience is
based on a sound with distortion, you are merely in a wrong musical
world.
There are no amps with '0 distortion'. Such is impossible at the current time! 0.001% is audible if there are no lower orders to mask their presence. This is due to the fact that the ear uses the higher orders to sense sound pressure, and so is keenly sensitive to their presence.
All amps make distortion, and since the ear converts all forms of distortion into tonality, this is the primary difference you hear between amps. IOW **everyone** is basing their auditioning experience based on a sound with distortion.
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