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

tomchr

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Would now be a good time for me to chime in? :)

In its current form, the HP-1 circuit doesn't lend itself well to mass production, mostly from a financial standpoint. As described earlier in this thread, the user experience will also need an upgrade if I want to get enough money for it to warrant mass production. For example, I'll need a different volume pot (Alps Blue) for a better feel (and better looks when Amir pops open the chassis :)). The Alps Blue won't fit in the HP-1 board as-is, so a new board is needed. I can also make some circuit modifications that will save cost without compromising the performance. In fact, it may improve it a tad. So I think it's fair to say that the HP-1, in its current form, is discontinued forever. It's still an amazing amp. I designed it as a statement piece. Now I just need the user experience and chassis quality to be statement pieces as well.

I will likely still use the "building blocks" within the HP-1 in future amps, so it's not like I'll be starting from scratch. I might as well leverage the investment I've already made.

I have plans for at least two headphone amps:
1) Lower cost, lower performance: Lower output power for sure. Hopefully, I can keep the THD, IMD, etc. at the HP-1 level. We'll see.
2) Higher cost, about the same performance as the HP-1 - maybe a little better. Much prettier chassis, larger volume knob, and better volume knob feel.

These amps will be fully built retail products. I haven't decided whether to market them under a new brand or whether I should leverage my existing brand and just have the new amps be a product line under Neurochrome. We'll see. Either way the retail products will have their own name to separate them from my DIY offerings.

Tom
 
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2) Higher cost, about the same performance as the HP-1 - maybe a little better. Much prettier chassis, larger volume knob, and better volume knob feel.
3) Higher cost, about the same performance as the HP-1 - maybe a little better. Much prettier chassis, no volume knob ;)
 

tomchr

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3) Higher cost, about the same performance as the HP-1 - maybe a little better. Much prettier chassis, no volume knob ;)
Should such an amp be digital-only then (i.e. USB, SPDIF, COAX inputs, no RCA/XLR)? Or still have analog inputs so you can use your favourite DAC?

Tom
 

tomchr

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I'd say still have analog inputs, no digital, so you could still use your favorite DAC and control volume there.
How about a volume control bypass option? Front panel switch + relay or something.

Tom
 

The Mule

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Hi. Tom - very nice to converse with you in person. :) I discovered the HP-1 after it was already discontinued. I think the final offer price to clear them out was $999? Even though I'm more in the at or below $500 range, I thought long and hard about one at the $999 price, equal parts because of the performance, but also a little because I have a feeling it will become a collector's item and (wait for it ...) perhaps even legendary. ;) But they were all gone by then too.

With that said, and keeping my $500-ish limit in mind, I'd certainly go for one in that range. I kinda wanted a THX AAA 789, but even though I requested in before the last drop, that supply was gone later that morning when I went to pull the trigger. *That*, was a little frustrating. So at least interim, I just got a Burson Fun.

But I'd still be interested in anything you do closer to my dollar range. I'd be looking for just an analog power amp (w/ a vol knob), with no DAC, and with RCA ins from an external DAC.

(I'll certainly keep an eye on this thread for updates too!)

I'm an engineer, materials (semiconductor process) not electrical, but man, you're kind of a rock star. :D
 

tomchr

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Thank you for the recognition. I'll try not to let it go to my head... :)

I'll see what I can do about a $500 amp. I've had that price point in mind for a while. It'd be nice with something there. In the end, it all comes down to chassis cost.

Tom
 

chriskilbourn

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Thank you for the recognition. I'll try not to let it go to my head... :)

I'll see what I can do about a $500 amp. I've had that price point in mind for a while. It'd be nice with something there. In the end, it all comes down to chassis cost.

Tom
Do you have an email list to announce when you’re releasing new products? I’d love to get the next higher priced version of the HP-1
 

tomchr

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tomchr

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I have good news for one of those of you who missed out on the HP-1. I now have one last HP-1 available. Or rather, to be available "soon". You can preorder it here: https://www.neurochrome.com/product/hp-1-ultra-high-end-headphone-amp-2/ I expect to be able to ship towards the end of the month, hopefully within two weeks.

Here's the story: I sold out three weeks ago while the chassis was still in manufacturing. My chassis vendor is having trouble with the manufacturing and keeps cutting the sides too short. It's only 1 mm too short, but that fails their own specs, which makes me wonder why they shipped them in the first place, but I digress... I also need to deliver a quality product, so I will keep pushing my vendor until they deliver the chassis as ordered. Anyway. At least the vendor is owning their mistakes and will remake the chassis. It just takes time. Unfortunately, one buyer got tired of waiting and has canceled his order. So I now have one left...

The buyer who backed out ordered the blue chassis, but that's traditionally been a slower seller. I'm trying to get my vendor to make it the grey version instead. I have the amp listed as blue, but there's a chance I can make it grey instead. I'll let the buyer decide and I will do my best to accommodate. Great sales pitch, I know. "Throw money at me. You get what you get..." :)

Ahh.... Life as a small business owner. :) Oh, well. The amp will sell.

Tom
 

chriskilbourn

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I have good news for one of those of you who missed out on the HP-1. I now have one last HP-1 available. Or rather, to be available "soon". You can preorder it here: https://www.neurochrome.com/product/hp-1-ultra-high-end-headphone-amp-2/ I expect to be able to ship towards the end of the month, hopefully within two weeks.

Here's the story: I sold out three weeks ago while the chassis was still in manufacturing. My chassis vendor is having trouble with the manufacturing and keeps cutting the sides too short. It's only 1 mm too short, but that fails their own specs, which makes me wonder why they shipped them in the first place, but I digress... I also need to deliver a quality product, so I will keep pushing my vendor until they deliver the chassis as ordered. Anyway. At least the vendor is owning their mistakes and will remake the chassis. It just takes time. Unfortunately, one buyer got tired of waiting and has canceled his order. So I now have one left...

The buyer who backed out ordered the blue chassis, but that's traditionally been a slower seller. I'm trying to get my vendor to make it the grey version instead. I have the amp listed as blue, but there's a chance I can make it grey instead. I'll let the buyer decide and I will do my best to accommodate. Great sales pitch, I know. "Throw money at me. You get what you get..." :)

Ahh.... Life as a small business owner. :) Oh, well. The amp will sell.

Tom
Bought it :) So excited. Black color would be amazing if possible.
 
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tomchr

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Awesome. Thank you. I really appreciate it.

I just got off the phone with my chassis vendor. It sounds like they've got things figured out. I'll receive a stack of enclosures tomorrow or Friday, so we'll see. I have a cautiously optimistic "I'll believe it when I see it" feeling here, but they do take quality issues seriously, so my confidence is above the noise floor at this time. :)

Your enclosure will have to be done separately as it was the only blue one in the stack. I can certainly change it to grey if you wish. I just tossed you an email about that actually. You could also go with carmine red, blue, or black. Or... Go completely custom with 'wheat' (yellowish tan colour) or light grey. With the latter two, I'd go with black text. The choice is yours. I like the graphite grey. It's very stealthy. Just let me know and I'll let my vendor know which powder to spray on the chassis for you.

Tom
 
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Your enclosure will have to be done separately as it was the only blue one in the stack. I can certainly change it to grey if you wish. I just tossed you an email about that actually. You could also go with carmine red, blue, or black. Or... Go completely custom with 'wheat' (yellowish tan colour) or light grey. With the latter two, I'd go with black text. The choice is yours. I like the graphite grey. It's very stealthy. Just let me know and I'll let my vendor know which powder to spray on the chassis for you.
Wow, lucky guy! Custom colors to pick from without the additional charge.
 

tomchr

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Yeah... Might as well make lemonade out of lemons. :)

The final HP-1 will be black with white lettering. I realized this afternoon, that this project is coming to a full circle that way. The first two chassis I had made for the HP-1 were black.

Tom
 

chriskilbourn

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Yeah... Might as well make lemonade out of lemons. :)

The final HP-1 will be black with white lettering. I realized this afternoon, that this project is coming to a full circle that way. The first two chassis I had made for the HP-1 were black.

Tom
It’s great to be a part of history haha.
Thanks! I can’t wait to hear it.
 

The Mule

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It’s great to be a part of history haha.
Thanks! I can’t wait to hear it.
Lucky guy. :)

Hi Tom - I'm reminded of an interview once I read with Andrew Jones, once of Pioneer, now working for Elac. He said it's easy to design a state of the art, cost is no object speaker. He said you just put in the best of everything. He said, the *real* challenge, is to design something a lot more cost effective, where you try not to give up much in performance to the state of the art, cost is no object speaker. He said that you're basically trying to optimize for all the cost constraints, but without making too many compromises for performance. Hopefully that makes sense, and I'll be super interested in how the ~$500 amp comes out! :D
 

JohnYang1997

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Lucky guy. :)

Hi Tom - I'm reminded of an interview once I read with Andrew Jones, once of Pioneer, now working for Elac. He said it's easy to design a state of the art, cost is no object speaker. He said you just put in the best of everything. He said, the *real* challenge, is to design something a lot more cost effective, where you try not to give up much in performance to the state of the art, cost is no object speaker. He said that you're basically trying to optimize for all the cost constraints, but without making too many compromises for performance. Hopefully that makes sense, and I'll be super interested in how the ~$500 amp comes out! :D
As far as I know the chassis is the most expensive component. To hack this, best way is to select a small, off the shelf chassis and design the pcb accordingly. To be honest the size of o2 is really not small for a good headphones amplifier design. You can put 6800uF capacitors in theire and you can have protection circuit, power management circuit. Put some surface mount components on the bottom side of the pcb is also possible, etc.
The only problem is that it won't look scary. It will look like a portable amp that's cheap and weak. That's a choice. In the end what counts is the true performance. Not some subjective garbage. Btw o2 feels 10 times better than atom. (I'm garbage sometimes)
 

tomchr

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He said, the *real* challenge, is to design something a lot more cost effective, where you try not to give up much in performance to the state of the art, cost is no object speaker.
Yeah. There is that. Basically, if you throw everything and the (gold/rhodium plated) kitchen sink into the project, as I did with the HP-1, you end up with something that's way too expensive. So you don't sell any. So you start developing some sort of portfolio. You'll need models A, B, and C. They all need to be cost-effective at their respective price points, and need to offer increasing performance for increasing price, or offer some sort of selling point that justifies the higher price tag. It's unfortunate that it works that way, but that seems to be how we roll in this market.

As far as I know the chassis is the most expensive component.
That's what I find as well.

To hack this, best way is to select a small, off the shelf chassis and design the pcb accordingly.
That sounds great in theory, until you realize just how few decent chassis there are.

The only problem is that it won't look scary. It will look like a portable amp that's cheap and weak. That's a choice.
Exactly!

In the end what counts is the true performance. Not some subjective garbage. Btw o2 feels 10 times better than atom.
I wish it was entirely about performance, because I have that down like nobody's business! It's all the touchy-feely stuff that will be somewhat uncharted territory for me. As you point out in your self-contradiction, the touchy-feely matters too. Why would I pay more for an Audi when I can buy a VW for considerably less? Maybe the suspension in the Audi is tuned a little differently. Maybe the engine is. Who knows. All I know is that I love my (now ten year-old) A3. Even if it is "just" a fancy Volkswagen.

Tom
 

JohnYang1997

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Hi Tom. I was playing around pre distortion for my test equipment. And it kinda works. I'm able to test high power distortion now.
Just to share that I'm using opa2189+tpa6120a2 composite.
And here is the distortion figure.
2.8V/500mW into 16Ohm
-596a04301f176949.png
-efd509aa9d1c04.png
 
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