Pass Labs HPA-1 Headphone Amp Review

[Southall-1998]

DIY WHAMMY on eBay UK - https://www.ebay.co.uk/itm/115571720376?hash=item1ae89c80b8:g:5mIAAOSwisFjXm3b&amdata=enc:AQAHAAAAoL81FUxk9o/wsmyOyg7UYIlTuCqLqzg2PUp8jM46JckiloS5vlAk/lOgp/pBDeNVZ30Z2YZT6iOtdNXnt1iboziHdB7eRo7cMmEKFC6KZgSOA0UkkpOs0qkpqpCN0bOHuR9uL7i5+XkXjVwa6ifJq7z0ibs3JeSNv+IAFt1c6/eHMOsCQkLxJUGeZU8okgc9flCK6LuE2UtpysHvXzmZY1o=|tkp:Bk9SR-ba-Z6UYQ

No connection with seller.

S.

 

[don'ttrustauthority]

Schiit's rejected design (due in part to lack of part availability) led to a 1000 unit release of their Magni 3(rejected) now called Piety by the company releasing it, Nitsch.

They are charging $149 and sold out in 12 hours, the 2nd harmonic is promised and measurements show delivered.

No power supply noise and slightly less money though.

 

[PoorishDecision]

Pass makes Death and Black Metal sound disgusting. If any amp consistently makes a whole genre sound bad, the amp us worthless no matter the price.

Black metal is known for it's terrible quality, a lot of death isn't particularly well recorded either. You can't turn mutton into lamb and a badly recorded album will sound bad on any halfway transparent equipment. On the brightside there's lots of really high quality remasters coming out and labels are putting more of a priority on sound quality these days.

 

[solderdude]

Schiit's rejected design (due in part to lack of part availability) led to a 1000 unit release of their Magni 3(rejected) now called Piety by the company releasing it, Nitsch.

They are charging $149 and sold out in 12 hours, the 2nd harmonic is promised and measurements show delivered.

No power supply noise and slightly less money though.

But it doesn't have the PASS logo, its small, doesn't have 2 inputs, and isn't expensive enough for people to connect their other expensive gear to.
Schiit pushes all the right buttons, small, good performance, cheap, lots of reviews etc.

 

[Vacceo]

Black metal is known for it's terrible quality, a lot of death isn't particularly well recorded either. You can't turn mutton into lamb and a badly recorded album will sound bad on any halfway transparent equipment. On the brightside there's lots of really high quality remasters coming out and labels are putting more of a priority on sound quality these days.

Who said I expected anything other than a raw and crude sound? It may sound bad to you; I love Fallen Angel of Doom in a transparent system. A perfect example in that regard is Sodom's In the Sign of Evil, which to me sounds a lot better than the re-recorded Final Sign of Evil.

I like the old stuff precisely because it sounds harsh.

 

[Drakkar Noir]

final thoughts about the amp from the review unit owner:

* HEADPHONE JACK. Have to agree with Amir on this one. This issue was actually justified by Jam in some interview (don't recall which one), the locking jack being one that is proven to be very reliable; but still IMO looks a bit off in the otherwise expensive looking amp. Also, the reliability is from what I assume is its presence in instrument amps for musicians on tour. This is irrelevant for a HiFi audio setup.

* MEASSUREMENTS. While it's easy to understand the argument about Pass having deliberately implement some distortion in the amp to have a more pleasing, tube-like HiFi sound at the cost of ultimate fidelity, why not just use tubes? For tube sound I simply use my VERY tubby DNA.
Still, given the kind of music I listen to (Pearl Jam, The Strokes), this whole thing about measurements is kind of funny. As if a perfect headphone amp would fix rock recordings!

* AMP FEET. This hasn't been mentioned here yet. The amp was sent with felt feet and was a little slippery and annoying. Contacted Pass Labs about this, and they said they had rubber ones but changed them to felt because of the amp's weight and how it would leave marks or something. @amirm did you notice this?

* NO XLR. This is a non issue for me, as I explained earlier the RCA-only Pass complimented my setup perfectly. I know Nelson Pass uses something called Super Symmetry as a design approach, in paper it's supposed to be a balanced like connection without XLR. Makes no difference to me.

 

[Billy Budapest]

I thought I would post this to clarify things a bit. This was designed by Jam and not Nelson or myself. It also isn't the commercial version of the WHAMMY. Jam was given autonomy in the project since headphones were an interest of his. Our website and numerous reviews and interviews make pretty clear who designs what.

If you want something that measures below .0005% distortion and noise look at the BA20018 circuit I did. It is in the public domain and I think you can even get boards for it.
The Whammy is another dedicated headphone amp you can build. It is an op amp driving source followers and you can roll in your favorite one and set the bias how you like.
FYI I don't make a penny on these.

Given the measurements on the HPA1 and the loose connector I would like to see it at the factory. Call and ask for Kent and he can arrange to get it back.

Wayne, is this you?

Just confirming. Always good to see members of the industry here!

 

[dustinyo]

Wow this is a shame, I don't own any of their products, but Pass Labs is a company I still root for to succeed. After seeing the internals and performance though, how in the world do they come up with the pricing that they do? There's no way this cost more than a few hundred dollars to manufacture.

 

[GPJ]

Wow this is a shame, I don't own any of their products, but Pass Labs is a company I still root for to succeed. After seeing the internals and performance though, how in the world do they come up with the pricing that they do? There's no way this cost more than a few hundred dollars to manufacture.

The parallels to abstract art huh?

 

[amirm]

they said they had rubber ones but changed them to felt because of the amp's weight and how it would leave marks or something. @amirm did you notice this?

I shipped the unit back to its owner already but pretty sure I remember it having rubber feet.

 

[WayneC]

Wayne, is this you?

Just confirming. Always good to see members of the industry here!

Yes that’s me.

 

[WayneC]

Wow this is a shame, I don't own any of their products, but Pass Labs is a company I still root for to succeed. After seeing the internals and performance though, how in the world do they come up with the pricing that they do? There's no way this cost more than a few hundred dollars to manufacture.

If a manufacture sells to dealers as we do the typical wholesale price is about half retail. One of the most expensive parts of the headphone amp is employee health insurance. Add in rent on a California building and paying a livable wage with a median home price of $800,000 and you can start to see where the money goes.

 

[Peternz]

Glad I never bought this. Thanks, Amir.

 

[Loomynarty]

Is this the commercial available version of the WHAMMY diy headphone amp that Wayne designed ?

Definitely not. WHAMMY uses an op-amp input stage with MOSFET output stage not JFET input stage like the HPA-1. WHAMMY was also designed years later and from the measurements I've seen, measures much better.

 

[KR500]

Definitely not. WHAMMY uses an op-amp input stage with MOSFET output stage not JFET input stage like the HPA-1. WHAMMY was also designed years later and from the measurements I've seen, measures much better.

Cool, that explains why it sounds fine as wine to me

 

[HiFiBob]

I've read all the reviews of the HPA-1. They're all very positive, except Amir's. I've also listened to the HPA-1. It played loud without noticeable distortion. It was detailed but not really neutral, which makes sense given the design. It's a relaxing sound and gets a good groove on. That's just my subjective impression, don't freak out.

Reverse-engineered schematics for the HPA-1 are posted on diyaudio.com. I put the circuit in SPICE and it simulates almost exactly the same as the Stereophile curves. The HD650 is rated 100 dB/mW sensitivity. The HPA-1 shouldn't break a sweat driving these headphones to ear-splitting levels. I want to say, if Amir's listening test is valid, the review amp was probably damaged in shipping, beyond the loose control board connector. Or maybe it was just worn out from being left powered on continuously for years (bad idea).

I wish Amir had arranged to have the amp inspected at the factory before publishing such a scathing review.

Measured -83dB SINAD seems bad, but don't forget it's a log scale. THD of 0.007% is still very low, below the audible threshold, and it'll be lower at normal signal levels. There's no real need for amps with vanishingly low distortion. This is just a marketing gimmick, not an objective or "scientific" requirement.

I wouldn't buy this amplifier myself for a bunch of reasons. But I don't hate it for existing. I'm glad there are choices in the market. I appreciate that Nelson Pass employs American workers and provides them health insurance and benefits. You can build your own HPA-1 clone. Good luck making it the same quality for under a thousand dollars, and that doesn't account for the costs of labor, marketing, customer support, and keeping the factory lights on.

It legit makes me sad to see people hating on this amp, and I'm not even a Pass fanboi. I do get tired reading about cookie-cutter Chinese gear all the time. Pass Labs' design philosophy is different. It's a big world, full of injustice. There are plenty of more important things to lose sleep over. IMHO and YMMV.

 

[Extreme_Boky]

You see, with all these $100 devices that measure phenomenally well, but sound like crap.... this site will slowly get to a point where.... there will be no point to measure anything anymore. Of course, there will be $50 devices in a year that will measure better than the current $100 device... but people will lose interest. What's the point? Who cares... at that price point the subjective vs objective would lose any meaning.

What will remain is going to be the question: despite the phenomenal measurements that Amir is showing here, why does this still sound like crap...

 

[Alcophone]

I wish Amir had arranged to have the amp inspected at the factory before publishing such a scathing review.

That would have been up to the new owner, Amir had to wrap up the review because the owner at the time sold it to someone else who was waiting to receive it.
But yeah, if this unit makes its way to Pass Labs, I'd love to hear their findings.

This amp is really bad because whenever I foolishly decide to listen to a few songs before going to bed, I keep listening way longer than I should.

 

[Extreme_Boky]

Hah! This is why I refrain from listening to music before bedtime.

 

[oleg87]

Measured -83dB SINAD seems bad, but don't forget it's a log scale

Worth pointing out that human perception of loudness is also logarithmic.

Agree that the vitriol against such amps is silly. This amp is not advertised as a measurement monster, and seems to more-or-less meet its limited provided specs, so any mismatch of expectations and the numbers coming out of an AP box is on the person spending four grand on such an amp.