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

Veri

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One thing that did drive the choice of this connector was that I wanted it gold plated. The gold plated version with the right (red) connector on the bottom was special order. The version I use is readily available. I'm sure you've seen enough oxidized nickel plated connectors in your lifetime. :)

Tom

I love the gold plated connectors in the picture :) good job/good choice!
 

escalibur

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Also, now that most of the numbers are in, it looks like I'll have to increase the final price to $899.

No offense but after seeing how well Geshelli Archel 2, SMSL SP200, Monolith THX 888, Topping DX7 Pro (includes a balanced DAC too) are measuring it would be very hard to imagine why would anyone want to pay that much extra for HPA-1. I'm not trying to rain on your parade but bad pricing can really ruin solid products. Not because the product might not be worth as much but because the rivals might be offering very similar (if not better) performance with much cheaper price.

For sub $400 HPA-1 would be so easy to recommend. $899 + shipping + taxes = the final price is over $1k.

Anyways it will be interesting to see how well HPA-1 will be doing in 1-2 years from now.
 

Veri

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For sub $400 HPA-1 would be so easy to recommend. $899 + shipping + taxes = the final price is over $1k.
Anyways it will be interesting to see how well HPA-1 will be doing in 1-2 years from now.

Neurochrome is in the premium market segment, he could never manufacture in the $400 price range. It depends on what you want.

Archel is super barebones, Atom is super plasticky. Massdrop/Monoprice/SMSL knob are likely to have a little volume imbalance or even scratchy noise, not to mention SMSL is going for a much broader audience considering they manufacture and sell in Asia which can cut their costs by a lot. Going by pictures the SP200 doesn't look very premium next to the pictures of the HPA-1 in this thread.
 

escalibur

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Neurochrome is in the premium market segment, he could never manufacture in the $400 price range. It depends on what you want.

Archel is super barebones, Atom is super plasticky. Massdrop/Monoprice/SMSL knob are likely to have a little volume imbalance or even scratchy noise, not to mention SMSL is going for a much broader audience considering they manufacture and sell in Asia which can cut their costs by a lot. Going by pictures the SP200 doesn't look very premium next to the pictures of the HPA-1 in this thread.
That's very true but again. It's it that much premium to justify the price difference? :) Let's see what will future bring.
 

tomchr

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Not because the product might not be worth as much but because the rivals might be offering very similar (if not better) performance with much cheaper price.
I'm not planning to join the race to the bottom. I recently ordered a Topping D30 DAC from Amazon. It was sold as "new" but had clearly been opened, used, and returned. It wouldn't even turn on. That's what the cheapies look like, so I'm really not concerned. I don't doubt that Topping can deliver a good product (you can find measurements of the D30 on this forum), but my experience was pretty bad. It meant I'll be attending Burning Amp with a $25 eBay DAC rather than a decent DAC (I'm not bringing my $1100 RME ADI2 DAC for this!). Good products need to be backed by a good distributor network. I developed a lot of connections for that while I was at RMAF.

Pricing yourself too low to start can ruin a brand as well.

For sub $400 HPA-1 would be so easy to recommend. $899 + shipping + taxes = the final price is over $1k.
If you find your taxes to be too high, you should take it up with your government. Canada has trade agreements with many countries, so the customs duties should be fairly low. In many places (Canada, EU, likely others) you will likely have to pay your local sales tax or VAT on import. Such is life. I pay taxes too.

Anyways it will be interesting to see how well HPA-1 will be doing in 1-2 years from now.
That it will. I think I have a strong marketing message around delivering well-engineered products, manufactured on a quality process, backed by science.

I suggest you read some of Restorer-John's posts. He sees amps of varying quality levels from a repair guy's or restorer's perspective. Building an amp that lasts and holds up to years of use is a challenge, and many of the cheapies on the market don't follow the manufacturers' recommendations regarding mechanical support of the components (headphone jack and volume pot in particular). They are guaranteed to fail over time. But the amps are so cheap, that the manufacturers rely on you just buying another one when the amps fail.

Neurochrome is in the premium market segment, he could never manufacture in the $400 price range. It depends on what you want.
Exactly!

I can go two ways from the HPA-1: Up in price (so fancier chassis, more features, more premium) or down in price (less fancy, fewer features, not as premium).
Going up in price is more fun, because I can be more creative in the engineering, which would allow for a true statement amp (which is what the original HP-1 was supposed to be, actually).
That said, I am intrigued by the "down in price" route as well. You would have to give up features. No differential input for you! No fancy Alps pot. You get the li'l green Alps RK097 instead as that's 80% lower cost than the RK271. Maybe only one gain setting... Lower output power. I think it would be nice with a $300-400 amp as a stepping stone on the way to the more premium products.

That said, I should probably sit down and think long and hard about this from a business strategy perspective. Perhaps ask my advisors...

That's very true but again. It's it that much premium to justify the price difference? :) Let's see what will future bring.
Yeah. I suppose you can always hope that I go down, so you can be left with the various cheapie products. ;)

I plan to stick around, though. Someone will always want a quality product and that's what I intend to deliver.

Tom
 
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Yviena

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@tomchr just curious but is the specified 250mW at 300 Ω the maximum power the amp can do, or can it go higher in power but with increased distortion?
 

Barce

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Really nice to see your hard work and planning come to fruition. That's one attractive unit. I'd coinsider join the 40 preorders (and support Canadian engineering/manufacturing) if I could justify dropping 1k on an amp right now, but the Topping DX3Pro is still covering all my headphones like a champ. I hope the process continues to go smoothly!
 

tomchr

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@tomchr just curious but is the specified 250mW at 300 Ω the maximum power the amp can do, or can it go higher in power but with increased distortion?
The amp starts to clip at 250 mW into 300 Ω. I could probably play the specmanship game and claim 300 mW (or maybe more) at 10% THD, but that's not how I operate.

Tom
 

Azeia

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@tomchr

tcahpa1-rcacomparison.png

Maybe it's not important, but I notice the earlier one seemed to have what look like plastic insulation between the RCA and chassis. I remember you mentioning this in a prior post:
The solution to the ground loop issue is simple: Use a differential connection. I also help you out by leaving the signal ground floating relative to the chassis safety ground. I actually use the differential receiver even when you select the RCA inputs. The signal path is differential all the way to the volume control.
Maybe this is a stupid question, but for the signal ground to be 'floating' relative to the chassis, doesn't that mean you need those rubber or plastic isolators between the RCA jacks and chassis?

Oh, and another question, just to confirm, since this obviously can't be seen in the pictures; it's still your plan to also have a plastic sheet at the bottom of the chassis to prevent risk of mains shorting to the chassis, as an extra layer of safety? (in case of bad house wiring, etc, you'd also mentioned this in a prior post, but it's been awhile so I don't know if the design has changed since then)
 

escalibur

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I'm not planning to join the race to the bottom. I recently ordered a Topping D30 DAC from Amazon. It was sold as "new" but had clearly been opened, used, and returned. It wouldn't even turn on. That's what the cheapies look like, so I'm really not concerned. I don't doubt that Topping can deliver a good product (you can find measurements of the D10 on this forum), but my experience was pretty bad. It meant I'll be attending Burning Amp with a $25 eBay DAC rather than a decent DAC (I'm not bringing my $1100 RME ADI2 DAC for this!). Good products need to be backed by a good distributor network. I developed a lot of connections for that while I was at RMAF.

Pricing yourself too low to start can ruin a brand as well.
That's also very true. Finding the right balance is damn hard and only time will tell how well or poorly it went.

If you find your taxes to be too high, you should take it up with your government. Canada has trade agreements with many countries, so the customs duties should be fairly low. In many places (Canada, EU, likely others) you will likely have to pay your local sales tax or VAT on import. Such is life. I pay taxes too.
Eg. in Germany they are 19%, in Finland 24%. I'm not sure do they (or EU in general) have any deals with Canada or not. I'm not against paying the taxes I was speculating the final price because on a level of $1k 20% of 'extra' price might be a deal breaker for some. I'm not arguing should it or not. It's up to everyone's own opinion and choice.


That it will. I think I have a strong marketing message around delivering well-engineered products, manufactured on a quality process, backed by science.

I suggest you read some of Restorer-John's posts. He sees amps of varying quality levels from a repair guy's or restorer's perspective. Building an amp that lasts and holds up to years of use is a challenge, and many of the cheapies on the market don't follow the manufacturers' recommendations regarding mechanical support of the components (headphone jack and volume pot in particular). They are guaranteed to fail over time. But the amps are so cheap, that the manufacturers rely on you just buying another one when the amps fail.

Unless we are speaking of some really poor made amps I don't think that majority of the brands (JDS Labs, FiiO, O2, Monolith...) mentioned on this forum will actually fail within years. Yes there are bad apples in every basket.


Exactly!

I can go two ways from the HPA-1: Up in price (so fancier chassis, more features, more premium) or down in price (less fancy, fewer features, not as premium).
Going up in price is more fun, because I can be more creative in the engineering, which would allow for a true statement amp (which is what the original HP-1 was supposed to be, actually).
That said, I am intrigued by the "down in price" route as well. You would have to give up features. No differential input for you! No fancy Alps pot. You get the li'l green Alps RK097 instead as that's 80% lower cost than the RK271. Maybe only one gain setting... Lower output power. I think it would be nice with a $300-400 amp as a stepping stone on the way to the more premium products.

That said, I should probably sit down and think long and hard about this from a business strategy perspective. Perhaps ask my advisors...

Please do so. :) I really wish we could have more competition in sub $1k class. I'm not saying that every amp should cost as low as that but to at least to have an option. The more choices we have the better. Yes making more choices means more costs but then again that might catch some new buyers for your products who would otherwise just skip that $1k option.

Yeah. I suppose you can always hope that I go down, so you can be left with the various cheapie products. ;)

I plan to stick around, though. Someone will always want a quality product and that's what I intend to deliver.

Tom
Let's not put words in others' mouths mate. :) I never said I hope that you go down. Don't understand me in a wrong way. I was just speculating the differences between the qualities and prices. People will decide over time regardless of your or mine opinions. :) I'm sure that the more people talk about your products here and on the other forums the better it is. :) Cheers!
 
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tomchr

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Maybe this is a stupid question, but for the signal ground to be 'floating' relative to the chassis, doesn't that mean you need those rubber or plastic isolators between the RCA jacks and chassis?
The RCA connectors in the new design are indeed grounded to the chassis. That provides better RFI/EMI immunity. I've used the amp that way in a variety of setups and not had an issue. When you select the RCA connectors, the differential input is used to sense the voltage difference between the RCA centre pin and the RCA shell/ground.

Oh, and another question, just to confirm, since this obviously can't be seen in the pictures; it's still your plan to also have a plastic sheet at the bottom of the chassis to prevent risk of mains shorting to the chassis, as an extra layer of safety?
Yes. I still plan to have the HPA-1 meet current standards on electrical safety. :)

Tom
 

elira

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@tomchr How does your design compares to those from Kevin Gilmore? As far as I understand your approach is closer to the one used in THX AAA amps than the one used in class A amps.
 

tomchr

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That's also very true. Finding the right balance is damn hard and only time will tell how well or poorly it went.
True that.

Eg. in Germany they are 19%, in Finland 24%. I'm not sure do they (or EU in general) have any deals with Canada or not.
If you google "Canada EU trade agreement" you'll find this: Canada-European Union Comprehensive Economic and Trade Agreement (CETA). It went into effect September 21st, 2017.

Please do so. :) I really wish we could have more competition in sub $1k class. I'm not saying that every amp should cost as low as that but to at least to have an option. The more choices we have the better. Yes making more choices means more costs but then again that might catch some new buyers for your products who would otherwise just skip that $1k option.
Similarly, some will skip a brand if they don't have a $3k option.

I appreciate your input. I'll see what I can do.

Tom
 

tomchr

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@tomchr How does your design compares to those from Kevin Gilmore? As far as I understand your approach is closer to the one used in THX AAA amps than the one used in class A amps.
No idea. Do you have measurements for the Gilmore designs? Or schematics or block diagrams?

My composite amps rely on feedback and error correction to achieve stellar performance. The THX AAA topology relies on feed-forward. So they're different animals.

There are many approaches to Class A design. Class A just means the output devices conduct current at all times. In other classes, they turn off at some part of the sine wave cycle. I could take a Class A output stage and apply error correction to it and get good performance.

Tom
 

Azeia

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Yes. I still plan to have the HPA-1 meet current standards on electrical safety. :)
Well, from what I understand, most companies choose either Class II double-insulation and use ungrounded 2-prong plug (with insulation in the form of a plastic sheet to prevent mains from shorting to the chassis, or an external power supply), or they go Class I with a grounded 3-prong plug and then don't bother with any other protection.

I wish going overkill with the protection was part of the current standards for all consumer electronic products out there! =p

I've used the amp that way in a variety of setups and not had an issue.
Ah, so ground loops shouldn't be a problem then? Sorry, I'm not experienced enough with how all this stuff works inside to understand all the tradeoffs of the different approaches, etc.
 

elira

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Do you have measurements for the Gilmore designs? Or schematics or block diagrams?

I haven't seen serious measurements of his amps, but they are highly regarded on DIY communities, here's a schematic of one of the popular ones:
1573157326332.png
 

tomchr

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Well, from what I understand, most companies choose either Class II double-insulation and use ungrounded 2-prong plug (with insulation in the form of a plastic sheet to prevent mains from shorting to the chassis, or an external power supply), or they go Class I with a grounded 3-prong plug and then don't bother with any other protection.
I have followed the IEC standard for Class II with regards to insulation, isolation, and creepage. But I am grounding the chassis just in case all that insulation/isolation fails (which is exceptionally unlikely). So technically, that makes the HPA-1 a Class I device.

I wish going overkill with the protection was part of the current standards for all consumer electronic products out there! =p
I'm definitely closer to overkill than most. Hence the need for that plastic (Delrin/Acetal) sheet below the mains section of the PCB.

Ah, so ground loops shouldn't be a problem then?
To the best of my knowledge, no.

Tom
 
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tomchr

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I haven't seen serious measurements of his amps, but they are highly regarded on DIY communities, here's a schematic of one of the popular ones:
I would expect an amp like that to struggle to reach 0.01% (-80 dB) THD mid-band due to its low loop gain. With the use of JFETs, I'd expect predominantly low-order harmonics, though with the fixed bias on the output stage, a smattering of odd-order and high-order distortion products could show up due to crossover distortion. It looks like a half-decent design, though. Better than some other DIY options I've seen.

Not everything hailed by the DIY community as the Goose That Lays Gold Eggs performs well.

Tom
 

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The RCA connectors in the new design are indeed grounded to the chassis. That provides better RFI/EMI immunity. I've used the amp that way in a variety of setups and not had an issue. When you select the RCA connectors, the differential input is used to sense the voltage difference between the RCA centre pin and the RCA shell/ground.
Exactly, all RCA connectors should be connected to the chassis at the connector. Neil Muncy (RIP) wrote about this some 25 years ago.
 
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