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Pass Labs HPA-1 Headphone Amp Review

Rate this headphone amplifier:

  • 1. Poor (headless panther)

    Votes: 320 90.4%
  • 2. Not terrible (postman panther)

    Votes: 19 5.4%
  • 3. Fine (happy panther)

    Votes: 6 1.7%
  • 4. Great (golfing panther)

    Votes: 9 2.5%

  • Total voters
    354
OP
amirm

amirm

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maybe they had different "audiophile fuses" in them ???
Funny there as the manual says use of "audiophile" fuses could void the warranty! So on that front at least, they are speaking the truth....
 

milosz

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Perhaps the chassis was not filled with oxygen-free air.......
 

AndreaT

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Someone gets a "minus F" for not doing their work:
Pass Labs' HPA-1 offers superb measured performance that reflects equally superb audio engineering.—John Atkinson
vs
I can't express enough how the HPA-1 ruined the sound of the two headphones I tested with it. Had this been my only experience, I would have thought neither headphone is any good! This mirage of more distortion is good for you needs to go go away and commitment to fidelity restored. - Amir

For 3600$ it better measures like a Benchmark HPA4. Or else.
What is really suspicious in general is that neither Stereophile nor TAS ever write more than a hint of criticism on the equipment they test. I followed their recommendation when I purchased 12-13 yrs ago my last expensive CD player, an Esoteric X-05. Yes, it did sound OK, but surprisingly it has a noisy disc spinning mechanism, in spite of the many superlatives they spent on the description of its build quality. I isolated the tray with tongues of rubber and it has improved the noise a bit, a 5 cents fix in a $ 6,000 CD player.

After 20+ years of reading both magazines, I have not renewed by subscription, as I do not think they offer more than the flyer of the manufacturer. So, I am left to wonder if their measurements are a generation behind those of Amir.

Even if the HPA-1 were as good as John Atkinson’s measurement (please note that THD measurements are indeed similar to Amir’s) its price is too high by a factor of ten in comparison with the flawless HP Amps offered by Topping and SMSL.
 
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LazyBear

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OK, I will bite :) I own HPA-1 and could not be happier. I never turn it off, so warm up is not an issue. Owned quite a bit of Pass gear since Aleph as well. Pass gear delivers best combination of solid state and tube sound. Warmer sound and yet controlled and punchy bass. That‘s all. I am sure Levinson measures great, but I can’t stand ML sound. Neither I care about Krell. I tried many amps - Woo, Sennheiser, Sony, Auralic, some others, and Pass is the only one that fits me. Headphones are Meze Empyrium. Also own Focal Utopia, but dont like it much.
 

Palladium

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These are made in small numbers and built the USA, and as such they will be expensive. Here once again we have proof that "U.S. Made" and EXPENSIVE do not always translate to HIGH QUALITY.

AKA "Really made in China with screws put in the US"
 
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Metronomy

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The Stereophile review showed better THD results than Amir's test revealed. I wonder if there is a unit-to-unit performance difference here?

The use of a design that allows a little low order THD tends to make things sound more "tubelike" and more like the kind of sound produced by guitar amplifiers.... to some people this is "more musical;" and some research has shown that a little 2nd harmonic makes the stereo image sound "deeper." But this amp doesn't allow "a little" low order THD- it is way worse than "a little." I am surprised by the amount of power supply noise. That is inexcusable unless they are going for the "blues bar" sound here....

These are made in small numbers and built the USA, and as such they will be expensive. Here once again we have proof that "U.S. Made" and EXPENSIVE do not always translate to HIGH QUALITY.
$3,600 and I don't have a device almost the same as the other? The excuse of the craftsman is always to cover company deficits. I can think of almost undrinkable $150 craft whiskeys, but they are artisanal, do you want to put?
 

solderdude

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Someone gets a "minus F" for not doing their work:
Pass Labs' HPA-1 offers superb measured performance that reflects equally superb audio engineering.—John Atkinson
vs
I can't express enough how the HPA-1 ruined the sound of the two headphones I tested with it. Had this been my only experience, I would have thought neither headphone is any good! This mirage of more distortion is good for you needs to go go away and commitment to fidelity restored. - Amir

For 3600$ it better measures like a Benchmark HPA4. Or else.

Like with all reviews.... those that are positive about a product get more samples (which reviewers often get to keep) and more income (advertisements, exposure) as people want to learn how good something that readers/viewers want to buy is, acc. to some 'notable' reviewer.
That's how this business still works and has always been this way.

So in that light JA did his work (A+) and posted the most positive plots and knitted a nice story around it which only came to light because of Amir's measurements.
I am sure on subjective websites this review will be seen as a 'hack job' or 'Amir setting out to discredit Nelson Pass and plugging Topping'.

People see what they want to see.
 

Geert

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I am sure on subjective websites this review will be seen as a 'hack job' or 'Amir setting out to discredit Nelson Pass and plugging Topping'.

That already happened in the DIYAudio forum thread.. That's why it would be interesting to see a THD measurement with the HD 650 at practical listening levels. I only found one testimony of someone hearing distortion with this amp, and he thought it was an issue with the recording :oops:
 

Pablo27

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Hi All, so how much money would one need to spend in order to match this level of performance?
 

solderdude

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That already happened in the DIYAudio forum thread.. That's why it would be interesting to see a THD measurement with the HD 650 at practical listening levels. I only found one testimony of someone hearing distortion with this amp, and he thought it was an issue with the recording :oops:

The HD650 has higher distortion than the HPA-1 (which is -80dB opposite 2V with the HD650 as a load). The output R is more than low enough for a 300ohm load.
So you won't see any difference in headphone measurements also because of noise levels in headphone measurements.
2V is comfortable loud (without Harman type EQ)
At 8V (distortion knee HPA-1) the distortion reaches 0.1% (-60dB) and is 123dB SPL in the HD650. Far beyond what Amir measured the HD650 with (114dB)

The Stealth/Expanse, however, at impressive levels (> 2V DAC input) is reaching measurable levels.

Hi All, so how much money would one need to spend in order to match this level of performance?

That could be anything from $ 50.- to $ 50,000
The reason for this is that there is NO relation between price and performance.
 
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DSJR

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I just wanted to ask, what were the standards for this type of thing in 2015 when this unit was designed? Not sure when the HPA4 was introduced and I honestly don't know if Topping et al had got their act together in this sector back then. Not sure if the UK or even the EU has such a keen specialist headphone market as the eastern side (and the US) appears to have.

With respect to JA, he seems to need to damn with faint praise as Martin Colloms once did - you need(ed) to read between the lines to get what the reviewer really thought.

P.S. Surely, all these amps need to be is a low wattage low noise power amp (1 - 2WPC at 8 ohms) and that tech was sorted out many decades ago. Maybe I'm missing something and apologies if I am.
 

solderdude

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The only 'poor' performance is lack of gain (needs a source > 3.5V out in RCA) and the (intentional) amount of 2nd (and lower 3rd) harmonics, at least up to 2V out.
We can only guess the harmonic spread above 2V but that might not look great in low impedances.
The hum ... I can't say anything about that.
200mW in 300ohm and 3.5W in 20ohm (>0.1% distortion) could easily be reached in 2000 already.

Most people listen to music with just a few mW average and maybe 10-30mW peaks. (a bit more with insensitive low impedance headphones)
 

Geert

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2V is comfortable loud (without Harman type EQ)
At 8V (distortion knee HPA-1) the distortion reaches 0.1% (-60dB) and is 123dB SPL in the HD650. Far beyond what Amir measures (114dB)

The Stealth/Expanse, however, at impressive levels (> 2V DAC input) is reaching measurable levels.

Thanks for doing the math. I was looking for an explanation on how Amir heard clear distortion, while for a lot of headphone enthusiasts this is their end game amp and no one has any complains. It even is a popular DIY build with involvement of people with a good understanding of EE, but I can imagine non of these builds ever met an AP.
 

solderdude

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The distortion is intentional and can be designed this way (checked for the proper level) even with a half decent sound card.

The loose connector inside (quality control, those connectors do not come out with shaking the device), the lack of gain, the high price is what is questionable.
It looks like good quality components have been used and seems serviceable (no parts that will be obsolete or hard to replace a few years from now)
Would value this HP amp at around $ 400.-
 
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Geert

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The distortion is intentional and can be designed this way

I know, but from Amirs story it looks like what he heard was not just some 2nd and 3th harmonics adding a euphonic character to the sound: "the sound was miserable".
 

Sokel

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The loose connector inside (quality control, those connectors do not come out with shaking the device)
I admit I got a little alarmed but this so I slobby tested what it would take for such a connector to come off (I have an extra 1200as2 on my amateur test bench connected with jst connectors with ribbon I had in hand)
I didn't succeed with shaking in any possible way.
It must have been some serious abuse during posting maybe,or QC as you say.

Edit: Moreover it literally touches the PS's heatsink,main noise could be a lot better if tidier.
Edit 2: Can't be a QC issue as this belonged to a member and was already in use for a long time.
 
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okok

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Can someone answer the question when would spending over $1000.00 for a headphone amp be a good idea ? I’m seriously asking.

let me tell you some observation.

some on headfi claim that every DAC sounds the same, the modo output is the same as any standalone DACs, and at the same time exclusively using $10000+ amps over the years, and at the same time buying/selling vintage 30 yr old headphones to keep gaining profit, saying that vintage headphones (30 to 40 yo) better than any TOTL cans in the current (and of course attacking asr at the same time)

can we call this phoney? you can't really imagine the darkness of human heart.
 

Sokel

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and at the same time buying/selling vintage 30 yr old headphones to keep gaining profit,
I'll go there and put an 1000 euro price tag for my ancient orthodynamics :p.
 
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