Nelson Pass amps

[invaderzim]

The Chinese! They copy all the classics and sell the PCBs online for peanuts.

Pass
Accuphase
Quad
ML
etc.

While that is handy for the DIYer it isn't the manufacture giving it away. I doubt anyone from Accuphase will tell you which part you can use in place of the hard to get one they used or tell the person making the PCB how to lay it out the better.

That being said some of those Chinese vendors could clean up if they'd work with a fluent English speaker that also understands amps and put together some actual instructions and BOMs.

 

[Dilliw]

"The other fundamental thing—number 2—is that I am centrally aware that all this is just entertainment, mine and yours. The objective needs of amplifier users are largely solved on a practical level, and as [Marshall] McLuhan perceptively noted, when that happens, we turn our technology into art. For me, the art lies in making simple, unusual amplifiers that sound great and measure fairly well. They aren't for everyone, but if they appeal to even a narrow segment of audiophiles, I'm perfectly happy. I'm equally happy if they are reliable."
Nelson Pass

Read more at https://www.stereophile.com/content/nelson-pass-circuit-topology-and-end-science#A2Dwsy4ZFHGHxrAO.99

 

[audiopile]

Amongst my small group of DIY friends -none of us have built anything up from a PRC board yet ? Has anyone here had first person experience with selecting parts ,stuffin the board ,solderering ,caseing the result of one of these "clones" - has anyone heard or measured the result of one of these "clones" ? I doubt they'd be on dabay as consistently as they are if somebody wasn't buying them ? If somebody has got one they are happy with -submission to ASR for testing would be very interesting. I would think parts substitutions would be a big challenge -assuming you actually have a accurate detailed parts list for the "classic" 30 or 50 year old stereo gear you are trying to duplicate.

 

[SIY]

If someone is happy to steal a trademark, you can safely assume that the rest will not reek of integrity. I've not built or measured any Pass rip-offs, but I've had a few "Marantz 7C" go through here. Their resemblance to an actual 7C isn't particularly good (and the original 7C itself wasn't great, either), and they were full of low-bid parts, boards that would peel at the slightest rework, and terrible layout and part placement. I'll guess the story is the same for "Pass" and "Krell" and whatever else is the flavor-of-the-day for stealing.

 

[audiopile]

Ya - the line "Trust me - I only steal from the best." seems like it might be a warning ? I had been borrowing a buddy's spare service bench for years on Saturdays - this included his vacuum desoldering tool (when he closed his store we found the midwests largest collection of defunct desoldering tools in the basement -no parts available -not fixable -but he had cornered the market ) -last week I finally bought my own. I have always hated desolderering components from traces ( way too often I over heat and make a mess to fix) vacume desolderering tools help me avoid this. I would like to give honorable mention to at least Bill Johnson era ARC stuff -big ,wide ,thick traces and chassis big enough to get at stuff (never been inside their new stuff).I think W.Z. Johnson recognized that tube stuff was going to need to be serviced and actually designed his stuff to be fixed - that is VERY nice and really rare.

 

[SIY]

Johnson's problem was the philosophy of "never use one tube where three will do."

 

[audiopile]

Ya -much as appreciated the D90B I owned (one of the best sounding amps to ever pass thru my hands) - the number of stages in that thing was amazing -the number of small tubes also amazing. In the long term -finding quality replacements for anything except the most commonly used tube types is going to be a challenge -but not until long after my listening days are over.Although -I wonder what EU power use standards are going to do to European tube amp/preamp manufacturers ? Or even importers from elsewhere into the EU ?

 

[despoiler]

My wife bought me the Pass Amp Camp Amp kit for my birthday. Easy build and I absolutely love how it sounds. The damping factor could be slightly higher, but it's not a deal breaker for me. The overall sound is alive and rich. Distorted guitars sound sublime. I play guitar so I'm hugely critical of how an amp delivers over driven tone. I appreciate what specs can tell us, but if it sounds good it sounds good. I'm definitely going to build another amp from Pass/First Watt.

 

[ahofer]

I have a Pass-designed Adcom 5802. It's a beast. Sounds great, runs really hot.

 

[cjfrbw]

My wife bought me the Pass Amp Camp Amp kit for my birthday. Easy build and I absolutely love how it sounds. The damping factor could be slightly higher, but it's not a deal breaker for me. The overall sound is alive and rich. Distorted guitars sound sublime. I play guitar so I'm hugely critical of how an amp delivers over driven tone. I appreciate what specs can tell us, but if it sounds good it sounds good. I'm definitely going to build another amp from Pass/First Watt.

Apparently, NP listens to this amp himself when he is doodling at his bench. Low power, single ended, but I don't think I have ever heard a person who did not like it's sound.

 

[jsrtheta]

Johnson's problem was the philosophy of "never use one tube where three will do."

That's just one of his problems.

 

[jsrtheta]

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.

The late Tom Nousaine drove down to Florida back in the '90s and visited the late Steve Zipser, who owned Sunshine Stereo. Nousaine had challenged Zipser to submit to ABX testing. Zipser contended he could differentiate his Pass amp from whatever Nousaine brought to the field. Nousaine brought a cheap Yamaha amp (an integrated, if memory serves).

Neither Zipser (who was a pretty decent guy) nor his wife could score better than chance in the tests.

I have no reason to believe Pass makes anything but good amplifiers (I've had some of his Adcoms), but I don't think I'd pay the higher prices he gets based on superior sound. Build quality, reliability, these are grounds on which to pay more, and I've never heard of too many problems with Pass in this regard.

 

[tmtomh]

I had a GFP-565, there was noticeable hiss with efficient speakers, overall I felt it was somewhat overrated but I wasn't using the phono section. Has nothing to do with NP though.

I have an Adcom GFA-5400 power amp that I like very much, and I respect Nelson Pass for all the reasons stated here. But I have to agree about the GFP-565 - it's a noisy preamp (I had the exact same hiss experience), and overrated IMHO.

 

[Sal1950]

I have no reason to believe Pass makes anything but good amplifiers (I've had some of his Adcoms), but I don't think I'd pay the higher prices he gets based on superior sound. Build quality, reliability, these are grounds on which to pay more, and I've never heard of too many problems with Pass in this regard.

I agree with reservations. If your talking about the expensive Pass line of amps the deal on them is the beauty and quality they exude just sitting on the rack. So ya if the $44,000 a pair for a XA200.8 mono's didn't mean any more to me than the $200 I paid for my used Adcom 545 II, I'd have a rack full of 10 for my multich rig. These freakin things are beautiful! I guess beauty is in the eye but being a machinist myself I drool over the beauty of all the crafted aluminum. Yep a rack full, and a Bugatti Veyron sitting outside too.

 

[despoiler]

Apparently, NP listens to this amp himself when he is doodling at his bench. Low power, single ended, but I don't think I have ever heard a person who did not like it's sound.

It's got mojo in it's sound for sure. I'm debating if I want to build a second and run them as mono blocks or build a different higher power amp. One ACA is just barely enough volume for my room and speakers.

 

[gvl]

Maybe you can find a Nakamichi PA-7 in a good shape for a price of about 2 ACA kits.

 

[despoiler]

Maybe you can find a Nakamichi PA-7 in a good shape for a price of about 2 ACA kits.

I'll take a look. Thanks for the suggestion. I already have 1 ACA so a second isn't too expensive. Plus I enjoy the building aspect of DIY.

 

[manisandher]

Many years ago, I owned a pair of Pass X600 monos. Rock solid. I blew quite a few bass drivers in various speakers with these bad boys.

I had an Aleph 4 for a few years too. Nice sounding, but obviously not neutral.

Right now, I use a pair of First Watt F5-cloned monos in my main system. This design is more 'conventional' than NP's other FW offers. I think these may actually be the best sounding amps I've ever owned. And they measure very well - very low noise floor and THD, and their recreation of a 200kHz (not 20, but 200!) squarewave is almost perfect.

I've got a pair of ACA balanced monos coming my way in the next few days (put together by the same guy who made my F5 monos), for my office system at home. I'm sure they're going to sound great.

Mani.

 

[invaderzim]

I have an Adcom GFA-5400 power amp that I like very much, and I respect Nelson Pass for all the reasons stated here. But I have to agree about the GFP-565 - it's a noisy preamp (I had the exact same hiss experience), and overrated IMHO.

I'm not sure how many of these amps are directly designed by Nelson. From his posts on the other forum he'd often design the first version of an amp and then on the later ones Adcom would add things. So a lot of them could be Pass inspired but not his actual design.
I don't think he did any of the preamps because even at Pass Labs he has Wayne Coburn do those.

I couldn't bring myself to $4,000 or $5000 for any amp but I have been tempted quite often by used GFA-535 or 545 amps and if you like to build then the 'official' clone boards available can make a really affordable class A amp that is a lot of fun.

It's got mojo in it's sound for sure. I'm debating if I want to build a second and run them as mono blocks or build a different higher power amp. One ACA is just barely enough volume for my room and speakers.

It is a much more involved build and made harder since there isn't a complete kit but going with something like an M2 or M2x is in a completely different league from the ACA. I miss my M2 a lot.

 

[gvl]

Is GFA-535 a NP design? I have a 2535 which is 2x 535s in one chassis, I know it is "well regarded" but I find it too warm sounding and it runs out of steam pretty quickly even when driving efficient Klipsch speakers. It did help to mask some of the JBL-L100s ills though at low to mid volumes.