Any opinions? Nelson is certainly no fool and a well respected subject expert, but my impression he's more in the "sounds good" than in the "measures good" camp. Just trying to place the "NP" brand in the right perspective for myself.
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Nelson Pass amps
- Thread starter gvl
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It's hard to say if the mediocre measurements actually affect the sound. AFAIK, no-one has done an ears-only comparison to a better measuring amp.
No question that the story is entertaining, and that's what Nelson is all about. He's a very smart guy and a damn nice one as well.
No question that the story is entertaining, and that's what Nelson is all about. He's a very smart guy and a damn nice one as well.
Sold his stuff back when he and Renee (?) owned Threshold - to this day -some of the best stereo gear I've ever heard. Really appreciate his practice of releasing his older designs to the DIY crowd . Might just be as nice a guy as Stew Hegeman.
Mediocre measurements? Where are you getting that canard? Probably from one of the lying rags - egad - those guys have no idea what they are speaking about.
I own Pass kit - an X-150.5 - and to my ears and taste it is the BEST solid state amplifier I have ever heard. Very powerful - a hallmark of Pass is that their offerings typically provide about 10% more wattage than rated. Great tone - all of the nice tonality and timbre shadings of tubes and transformers without the mush and soggy tendency of same.
Most of the mainline Pass amps - was the .5 series and now .8 - offer approximately 10% of the rated max power in Class A at idle. My X-150.5 actually does about 15 watts of pure Class A - which means that I can listen to a lot of music entirely in Class A mode. Pass amps can handle very low speaker impedance - I have speakers that drop below 2 ohms with two 12" woofers in parallel and the Pass amp pushes them with no problem - to high levels of room sound. Very rugged devices those Pass amps.
Pass amps seem to cause the music to just appear in the air - no strain, no sense of amplification, no mechanical feeling of something "pumping current". A truly wonderful amplifier from a top notch company known for their integrity and customer service.
BTW: Pass amps are extremely reliable - EXTREMELY SO. Rarely do they fail - which few other manufacturers can claim. I have had some fringe brands explode in sparks, flame and smoke - right in my living room. Avoid those folks. If you want names then PM me. I will share with you that the failing technology has mostly been Class D topologies.
I own Pass kit - an X-150.5 - and to my ears and taste it is the BEST solid state amplifier I have ever heard. Very powerful - a hallmark of Pass is that their offerings typically provide about 10% more wattage than rated. Great tone - all of the nice tonality and timbre shadings of tubes and transformers without the mush and soggy tendency of same.
Most of the mainline Pass amps - was the .5 series and now .8 - offer approximately 10% of the rated max power in Class A at idle. My X-150.5 actually does about 15 watts of pure Class A - which means that I can listen to a lot of music entirely in Class A mode. Pass amps can handle very low speaker impedance - I have speakers that drop below 2 ohms with two 12" woofers in parallel and the Pass amp pushes them with no problem - to high levels of room sound. Very rugged devices those Pass amps.
Pass amps seem to cause the music to just appear in the air - no strain, no sense of amplification, no mechanical feeling of something "pumping current". A truly wonderful amplifier from a top notch company known for their integrity and customer service.
BTW: Pass amps are extremely reliable - EXTREMELY SO. Rarely do they fail - which few other manufacturers can claim. I have had some fringe brands explode in sparks, flame and smoke - right in my living room. Avoid those folks. If you want names then PM me. I will share with you that the failing technology has mostly been Class D topologies.
https://www.stereophile.com/content/pass-labs-xa160-monoblock-power-amplifier-measurements
https://www.stereophile.com/content/pass-laboratories-xa608-monoblock-power-amplifier-measurements
https://www.stereophile.com/content/pass-labs-xa605-monoblock-power-amplifier-measurements
https://www.stereophile.com/content/first-watt-sit-3-power-amplifier-measurements
https://www.stereophile.com/content/first-watt-j2-power-amplifier-measurements
Not terrible, not great. So... mediocre.
Measurements of the XA200.8 monoblock:
https://www.stereophile.com/content/pass-laboratories-xa2008-monoblock-power-amplifier-measurements
That IM plot looks awful.
https://www.stereophile.com/content/pass-laboratories-xa2008-monoblock-power-amplifier-measurements
That IM plot looks awful.
Measurement excellence is not how Nelson entertains his target market.
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I certainly haven't. However, I have done totally invalid, long-term listening to Aleph 3 & ATI amps into Dunlavy SC-IVs. The Aleph's measurements hint that ABX testing would identify a difference quickly.
Subjectively, swapping amps doesn't change the character of the system. Recordings, speakers & room acoustics still rule, and I dispute any claims about "night & day differences."
That said, I believe I occasionally noticed small differences, even at non-clipping SPLs. Those few times, the ATI seemed to show a larger difference between recordings. Depth of soundstage & the quality of bass simply struck me as a bit more variable across recordings than with the Aleph. IOW, the Pass was probably a bit less transparent to the source - just as the measurements indicate. Either that, or I needed to use better cables.
He keeps a foot in both camps. The X line does accurate, the First Watt does tone control.
He's a smart man that knows how to make money in the audiophile market.
I run 5 of his Adcom GFA 5X5 II amps in my multichl rig.
Built like tanks, 25 years old and running strong.
Transparent, that's the bottom line.
Kudos for his contributions to the DIY crowd!
invaderzim
Senior Member
His First Watt stuff seems to be the antithesis of this forum. Low power, high heat products that go for sound that the customer base finds pleasing rather than an exactingly detailed representation of the data. Although when I fired up my M2 clone recently my guest's jaw dropped and their first words were "wow, that is detailed" so to each their own. They are designed for high efficiency speakers rather than to shake the walls with whatever gets plugged into them.
As Sal said Nelson has done a lot for the DIY community. Find one other high end amplifier maker that as soon as they stop producing an amp helps the DIY community build copies of it.
I'll also give Mr. Pass a lot of credit for just doing what he loves and letting others do and buy what they love. While we will likely see a lot of comments here about how bad the 'performance' of his amps are or how low powered they are and that people must be crazy to buy them I've never seen him badmouth any other type of amp that goes for something different than his.
I've also never seen him spout techo-bable to try to defend anything he makes. He will clearly state what the amp is doing and then typically just say something along the lines of "some people like it that way".
I know it will be heresy here but I do find the part of his product development interesting where he tweeks different prototypes slightly differently and sends them out to people he knows with no information on what is different about theirs and then gets their feedback on the sound.
All I know is I could just sit and listen to my M2 clone for really long periods and never get tired of it. Well, at least before I messed with it and blew it up...
cjfrbw
Senior Member
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I fired up my First Watt M2 yesterday, crossover-less to panel speaker @ about 88db efficiency. (Warning!! insane, subjectivist ranting content).
Yeah, it really sounded good. It is stated as a 25 watt class A, but I think that is just to stay within the 'First Watt' guidelines. I would say it is a 30W@8 ohms 50W@4 ohms going out to 3 percent distortion, with perhaps another 1-2db transient overhead. It is single pair MOSFET push pull with a transformer for voltage gain, and has no local or global feedback i.e. nearly as simple as possible with fewest stages and encumbrances.
My Pass Clone VFET 20 watt class A based on his DIY circuits is also a gem of a 'little' amp. Very special sound quality.
Pass says you can hear M2 go through class B, to class AB, to Class A as it warms up to reach temperature equilibrium after 30 minutes. I also found that although it sounds pleasant after 30 minutes, it needs a couple of hours of warm up to optimize. It seems like the upper midrange really tunes in only after prolonged warm up.
I am ancient enough to still believe that 25 watts of class A push pull is a lot of power in most instances. I can't clip it within any reasonably uncomfortable loud listening with the panel speaker, even with orchestral music.
Whether or not you agree with Pass artisan views and approach, he explores a lot of varying topologies for the 'audio restless' with his First Watt and DIY stuff while reserving most of his objectivist efforts in the Pass Labs big gun power houses. However, some of the First Watt philosophy has started to sneak in with the Pass XA 25.
Yeah, it really sounded good. It is stated as a 25 watt class A, but I think that is just to stay within the 'First Watt' guidelines. I would say it is a 30W@8 ohms 50W@4 ohms going out to 3 percent distortion, with perhaps another 1-2db transient overhead. It is single pair MOSFET push pull with a transformer for voltage gain, and has no local or global feedback i.e. nearly as simple as possible with fewest stages and encumbrances.
My Pass Clone VFET 20 watt class A based on his DIY circuits is also a gem of a 'little' amp. Very special sound quality.
Pass says you can hear M2 go through class B, to class AB, to Class A as it warms up to reach temperature equilibrium after 30 minutes. I also found that although it sounds pleasant after 30 minutes, it needs a couple of hours of warm up to optimize. It seems like the upper midrange really tunes in only after prolonged warm up.
I am ancient enough to still believe that 25 watts of class A push pull is a lot of power in most instances. I can't clip it within any reasonably uncomfortable loud listening with the panel speaker, even with orchestral music.
Whether or not you agree with Pass artisan views and approach, he explores a lot of varying topologies for the 'audio restless' with his First Watt and DIY stuff while reserving most of his objectivist efforts in the Pass Labs big gun power houses. However, some of the First Watt philosophy has started to sneak in with the Pass XA 25.
I've got a lot (thousands?) of hours enjoying music that went thru Pass designs: Pass era Threshold demo's at the store I worked at ,Adcom GFA-555 (original model) -owned up to three at any one time, Threshold S-200-II (recently sold -but thought long and hard before I sold it) -many hours over many years of enjoying what that amp did. Going to be restoring a GFP 565 -simply to see if it will live up to it's reputation as one of the best MM phono preamps ever ? Some guys catch my interest simply because they have long term earned and demonstrated reputations -right now -that's John Curl and Nelson Pass when it comes to amps/preamps. Not too many can call on decades of successful designs -these guys can.
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So performance close to, but not equal to an average AVR for only $21,000 per channel. Or maybe think about the Behringer A500.
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Maybe, but I don't know if that is quite right. He seems to be a guy who likes to investigate different circuit topologies for fun and curiosity. He found a market where he can sell it, and also help people DIY if they wish.
I remember trying things out just for fun like making a two transistor preamp. It worked very well, had bandwidth to 300 khz. Didn't have a good way to measure distortion then, but it was low enough it sounded fine. Made me wonder about some of the crazy complex designs you saw in preamps. Oh and taught me how important the power supply is on a simple circuit.
restorer-john
Grand Contributor
The Chinese! They copy all the classics and sell the PCBs online for peanuts.
Pass
Accuphase
Quad
ML
etc.
Zog
Active Member
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I have had the X150.8 for a couple of years. It runs hot, though you can leave your hand on it - only just. It is large and heavy - moving is definitely a two man job. Sound is on the warm side of neutral, to do with the mosfets I understand. Power is more than adequate for my needs (90 db speakers). It runs in class A up to about 13 watts. I hardly ever need that but the headroom is there if required. It ticks the audiophile boxes, eg soundstage. I like its looks - just a little bling with the power meter in the front.
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