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Review and Measurements of Neurochrome HP-1 High-Performance Amp

tomchr

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I think I've found the measurements of the Mystery Amp on the Forum to Remain Unmentioned that you're referring to.

No. That's definitely not the HPA-1. The HPA-1 performs significantly better than the Mystery Amp.

I do intend to ship the HPA-1 to Amir (and others) for review. I will focus on serious reviewers who are more likely to evaluate my products for what they are, rather than what they are not. It gets expensive to ship amps around the world and I need to ensure that I get the best return on investment.

Tom
 

Veri

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The SBAF "mystery" amp is supposedly quite cheap so I'd bet it's the geshelli "archel 2.5" amp but who knows

I do intend to ship the HPA-1 to Amir (and others) for review. I will focus on serious reviewers who are more likely to evaluate my products for what they are, rather than what they are not. It gets expensive to ship amps around the world and I need to ensure that I get the best return on investment.

Tom
Awesome! :cool:
 

Hugo9000

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@tomchr Calgary happens to be "north-west" of where I live, and being closer to the Pacific than to the Atlantic, it could even be called part of the "Pacific Northwest" in a rather broad sense (LOL). Is it possible that you are suspected of being NwAvGuy by some people, leading the kooks to target you or your products? :eek::facepalm:
 

tomchr

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Um... Calgary is 1000 km from the ocean and located in Alberta, one of the three prairie provinces in Canada. Lumping that in with the Pacific Northwest would be quite a stretch - not to mention factually wrong. We're on the east side of the continental divide after all. Now, kooks will be kooks, and you should never allow facts to get in the way of a good opinion, right?! :)

I suspect NwAvGuy is the guy behind JDS Labs. I suspect he either realized that the behaviour of NwAvGuy was undesirable from a business perspective and decided to let the "Guy" die, or the whole NwAvGuy story was a brilliant marketing ploy to generate a bunch of folklore around the O2. Either way, it seems to have worked. We're still talking about "him", right?!

I have noticed that I rub some subjectivists the wrong way with my hardcore scientific/engineering approach. I firmly believe in science and engineering. I do recognize that others don't value those things as much as I do. That's fine. We don't all have to value the same stuff. I strongly suspect there's a good chunk of people out there who do value solid science-based engineering and who would rather buy products that are rooted in those than products rooted in snake oil.

Tom
 

tomchr

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I've wondered about that as well but don't know anything about John's background. So, wild speculation alert! JDS is in Illinois, where a clever engineer might misdirect everybody while truthfully calling himself a Northwestern guy.
People move, right?! :) Yeah. Wild speculation. Maybe NwAvGuy was really an incarnation of the Fremont Bridge Troll.

Tom
 

solderdude

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Soooo.... Amir is the guy behind JDS labs ? :D o_O
 

solderdude

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The SBAF "mystery" amp is supposedly quite cheap so I'd bet it's the geshelli "archel 2.5" amp but who knows
Awesome! :cool:
More than likely given the specs posted HERE

Indeed.. the Magni-Heresy and as Veri mentioned doesn't measure as well as they purport it to be but it's only $99, metal enclosure and can deliver LOTS of power.

 
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Veri

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More than likely given the specs posted HERE
What. It's actually the new Magni LOL (unexpected)
https://www.schiit.com/products/magni-1
Doesn't look as good as SBAF hyped it. I see mains noise in several of their measurements. I guess it's good they keep offering better-than-average measuring gear, though. Priced very well at $99.

And to stay on-topic. Doesn't hold a candle to the HP-1.
 
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Yviena

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You know one measurement i want to see is Transient Intermodulation Distortion on amps, it's supposedly a fixed problem but you never know with some audiphile designs... i see it can be done using a low pass filtered square wave and a sine wave.

@tomchr I'm one of those who pre-ordered your HPA-1, i was looking forward to it for new year, the delay sucks tho. :/
 

JohnYang1997

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TIM was not an issue to begin with(for modern transistors). It's basically two more fundamental issues. Slewrate limitation and stability(phase shift, faster slewed front stages )in a feedback amplifier.
As music signal is merely 20khz. It will never trigger TIM.
To ensure the TIM not being triggered, a simple input low pass filter can completely prevent it.
 

Yviena

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TIM was not an issue to begin with(for modern transistors). It's basically two more fundamental issues. Slewrate limitation and stability(phase shift, faster slewed front stages )in a feedback amplifier.
As music signal is merely 20khz. It will never trigger TIM.
To ensure the TIM not being triggered, a simple input low pass filter can completely prevent it.
Hmm i see so in competently designed gear it's no problem, i bet though there exist some "audiophile gear" where this is still a problem though...
 

JohnYang1997

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Hmm i see so in competently designed gear it's no problem, i bet though there exist some "audiophile gear" where this is still a problem though...
It's never an issue with actual music signal. And even less so with headphone amps(smaller voltage swing and generally faster devices). I can't think of a way to cause TIM with music signal and not destroy frequency response. So it would be really difficult to do so. Might it happen in tube amps? but .....you know.
 

tomchr

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@tomchr I'm one of those who pre-ordered your HPA-1, i was looking forward to it for new year, the delay sucks tho. :/
Thank you for your preorder. Yeah. The delay sucks. Especially as I spent quite a bit of extra money getting the electronic bits together in time. Oh, well. #BeyondMyControl

On the upshot, I have a couple of prototype chassis. They're identical to the final version except in the final version the panels will be anodized after machining, so all holes will be black on the inside. I'll ship one to Amir for measurements once the electronics are in (in a week or two). I'll need to hang onto it as a demo model, though.

You know one measurement i want to see is Transient Intermodulation Distortion on amps, it's supposedly a fixed problem but you never know with some audiphile designs... i see it can be done using a low pass filtered square wave and a sine wave.
Yeah. The challenge is getting the audio analyzer to pick it up. I'll see what I can do for transient measurements.

TIM was not an issue to begin with(for modern transistors). It's basically two more fundamental issues. Slewrate limitation and stability(phase shift, faster slewed front stages )in a feedback amplifier.
As music signal is merely 20khz. It will never trigger TIM.
That's not true actually. If you read the original papers (Walt Jung, et al., AES, 1977), you'll notice that TIM/SID is caused by slewing of internal stages of an amplifier. In a design that has poor TIM/SID (TIM = Transient Intermodulation Distortion; SID = Slewing-Induced Distortion), it's perfectly possible to cause the internal stages to slew, even at audio frequencies. Build a preamp using the uA741 opamp and you'll see what I mean.

Now that we understand the mechanism that causes TIM/SID, we design amps that don't have the slewing limitations. Generally, this means ensuring that the internal stages run at sufficient bias current to drive the various capacitances in the circuit.

Amplifier stability is a different topic. Nyquist covered that back in the day.

To ensure the TIM not being triggered, a simple input low pass filter can completely prevent it.
True. Unfortunately, if your amp has poor TIM/SID when used with audio signals, you need to lower the cutoff frequency of the input lowpass to the point where it cuts into the audio bandwidth. Now the full-power bandwidth of the amp is limited to the point where the amp is useless for audio.

TIM/SID is a solved problem these days. I still think there could be value in a transient test of distortion, however. I suspect it could reveal potential thermal issues and thermal stability issues, in particular in power amps.

Tom
 

Julf

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You know one measurement i want to see is Transient Intermodulation Distortion on amps, it's supposedly a fixed problem but you never know with some audiphile designs... i see it can be done using a low pass filtered square wave and a sine wave.
It is fixed, apart from pathological designs, and they probably have other problems too.
 
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More than likely given the specs posted HERE

Indeed.. the Magni-Heresy and as Veri mentioned doesn't measure as well as they purport it to be but it's only $99, metal enclosure and can deliver LOTS of power.

What. It's actually the new Magni LOL (unexpected)
https://www.schiit.com/products/magni-1
Doesn't look as good as SBAF hyped it. I see mains noise in several of their measurements. Ehh~ typical Schiit? I guess it's good they keep offering better-than-average measuring gear, though.

And to stay on-topic. Doesn't hold a candle to the HP-1.
What are you two talking about? In both the SBAF and Schiit graphs, it measures better than many “recommended” amps here!
 

solderdude

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It does measure very well for a $99.- amp and better than a lot of ASR recommended amps.
I like the looks and price.

Similar to equal priced JDS labs Atom and Geshelli Archel 2 Pro but not better than the somewhat more expensive but less good looking Archel 2

300Ohm low gain Heresy.png


low gain Ar2.png



nchpa1.png


All well below any audible levels so equally 'transparent'
 
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tomchr

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What are you two talking about?
He's talking about the Neurochrome HP-1, the topic of this thread, which reached below -130 dB THD. The Tom Christiansen Audio HPA-1 is expected to reach below -130 dB as well. I have yet to confirm this by measurement as my APx525 can't measure that low.

Tom
 
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