Toss me an email. I'll be happy to help you out. Take my user ID here and add @neurochrome.com. You can also go through the Contact Us form on my website.
The LED blinks during the first ~10 seconds while the output DC voltage stabilizes. Then the output relays go 'click'.
The fact that the output relays click indicate to me that the amps have biased up correctly. That would not happen if the ±18 V wasn't working (step 6 on page 14). So I suspect your amp is actually working, but you had a measurement error when you measured the supply voltage. Obviously, double check before using the amp with headphones.
Tom
The LED blinks during the first ~10 seconds while the output DC voltage stabilizes. Then the output relays go 'click'.
The fact that the output relays click indicate to me that the amps have biased up correctly. That would not happen if the ±18 V wasn't working (step 6 on page 14). So I suspect your amp is actually working, but you had a measurement error when you measured the supply voltage. Obviously, double check before using the amp with headphones.
Tom
WOW! Finally completed my HP-1 and Tom I must say it is a gourgeous amplifier. Listening right now with my AKG K702, Source Mark Levinson ML390, CD David Darling, Dark Wood album on ECM and it sounds very impressive, right from the start. Perfectly silent, music just flow, very controlled and profond bass, great mids, crystal clear highs, very nice amplifier. Can't wait to let it warmup and settled. You were right to call it an Ultra-High_End Amp! Very sad that you discontinued this great project, but very happy that I got one 
Certainly now one of the best headphone amp in my collection...
SB
Certainly now one of the best headphone amp in my collection...
SB
Now that I've managed to complete the requirements for my psychology degree (formal graduation is in June), I'm looking to push full-time on Neurochrome. I have a few new products in mind, including some headphone amps, and would greatly appreciate your feedback on my ideas. If you have 15 minutes to spare, I would really appreciate your participation in my survey (linked to below).
Neurochrome Spring 2019 Survey (link).
The survey requires a sign-in via your Google/gmail account. Your email address will NOT be recorded. All your responses will be anonymous.
Thanks in advance.
Tom
Neurochrome Spring 2019 Survey (link).
The survey requires a sign-in via your Google/gmail account. Your email address will NOT be recorded. All your responses will be anonymous.
Thanks in advance.
Tom
Found this stellar reveiws of the HP-1 on audiosciencereview. Exactly the kind of performance I'm getting from mine. Too bad the HP-1 is discontinued, it was a great project and a fabulous HP amp... I'm glad I got one
Review and Measurements of Neurochrome HP-1 High-Performance Amp | Audio Science Review (ASR) Forum
Review and Measurements of Neurochrome HP-1 High-Performance Amp | Audio Science Review (ASR) Forum
Thank you for your vote of confidence. Yeah... The HP-1 was a "cost is no object" design. That's both its strength and its biggest flaw. It's a great design that will never be feasible to mass produce due to its cost.
I'm currently designing the PCB for the replacement. It'll be a retail product (sorry, no DIY). I am planning to have a prototype with me to RMAF, where I will be exhibiting in collaboration with Redscape Audio. Those interested in getting an email update once I open for pre-orders, should sign up for my newsletter: Sign Up to Stay Informed.
The prototype of the new design performs very well. It's not as powerful as the HP-1. It also has fewer features (only two gain settings) and uses plain Jane RCA connectors. That said, it's a very nice amp and should fit well in the market at the $599 price point I'm targeting.
Tom
I'm currently designing the PCB for the replacement. It'll be a retail product (sorry, no DIY). I am planning to have a prototype with me to RMAF, where I will be exhibiting in collaboration with Redscape Audio. Those interested in getting an email update once I open for pre-orders, should sign up for my newsletter: Sign Up to Stay Informed.
The prototype of the new design performs very well. It's not as powerful as the HP-1. It also has fewer features (only two gain settings) and uses plain Jane RCA connectors. That said, it's a very nice amp and should fit well in the market at the $599 price point I'm targeting.
Tom
Oh, I suppose I can throw a couple of teaser shots out there. Nothing glamorous. Those in the know will recognize the University of Washington Huskies colours (purple & gold) of OSH Park on the PCB. The final version will feature red solder mask and white silk screen.
It turns out this is also the Grande Reveal of the name of my retail brand: Tom Christiansen Audio. My products will be made in Canada. This includes the PCB manufacturing, PCB assembly, and product assembly. The chassis will be made in Japan.
For this prototype, I received three boards from OSH Park, so I'm trying a couple of different opamps. The build shown here uses the pre-production POPA1656 (P is for pre-production). I don't think it gets much more prototype than that. It's a nice opamp.
The prototype also uses the smaller ALPS RK097 rather than the (usually out of stock) RK271. The final version will use the RK271 (aka "Blue Velvet"). The final amp will also have a built-in power supply, feature an RCA input, have two gain settings, and contain a few features not commonly found on headphone amps in the $500-600 range, such as output DC protection.
I won't quote specs until the next prototype, which will be the pre-production HPA-1 prototype.
Now I get to learn Fusion 360 (formerly: Autocad) so I can get the chassis ordered. Yay.
Tom
It turns out this is also the Grande Reveal of the name of my retail brand: Tom Christiansen Audio. My products will be made in Canada. This includes the PCB manufacturing, PCB assembly, and product assembly. The chassis will be made in Japan.
For this prototype, I received three boards from OSH Park, so I'm trying a couple of different opamps. The build shown here uses the pre-production POPA1656 (P is for pre-production). I don't think it gets much more prototype than that.
It's a nice opamp.The prototype also uses the smaller ALPS RK097 rather than the (usually out of stock) RK271. The final version will use the RK271 (aka "Blue Velvet"). The final amp will also have a built-in power supply, feature an RCA input, have two gain settings, and contain a few features not commonly found on headphone amps in the $500-600 range, such as output DC protection.
I won't quote specs until the next prototype, which will be the pre-production HPA-1 prototype.
Now I get to learn Fusion 360 (formerly: Autocad) so I can get the chassis ordered. Yay.
Tom
Attachments
I'm designing the front panel of the HP-1's successor. I'm torn between using icons or text to indicate the function of the various knobs and switches. If you have a split second to take my one-question (yes, really! only one question!) survey, I would really appreciate it.
Here's the survey: Front panel design
Please resist the urge to just respond with your preference below. I would prefer to keep the results as uninfluenced as possible.
I've attached screen shots of the panel layouts. What's in orange will be printed in white on a black chassis. The only exception is the outline of the volume knob. That won't be printed. I just included it to give you an idea of its size.
Thanks in advance for your time and input.
Tom
Here's the survey: Front panel design
Please resist the urge to just respond with your preference below. I would prefer to keep the results as uninfluenced as possible.
I've attached screen shots of the panel layouts. What's in orange will be printed in white on a black chassis. The only exception is the outline of the volume knob. That won't be printed. I just included it to give you an idea of its size.
Thanks in advance for your time and input.
Tom
Attachments
If anyone has a board they'd like to sell I'd be interested - PM me
Post #412 here may be useful for you and others. If you don't find an HP-1, please do build the HP-2. I just received the board and it is immaculately organized and the measurements speak for themselves. In lower impedance loads, it only performs slightly worse than the HP-1, otherwise they are the same. It is less complicated to build as it requires little SMD which most likely means happier and more successful builds.
I'll be reviewing my HP-2 hopefully with a few headphones in hand and high end sources so you can get a subjective account on what it sounds like.
Best,
Anand.
Based on my listening to the railroad tracks, I'd venture to say that most HP-1 boards were built, so the odds of finding a bare board are quite low. Not zero, of course. Fully assembled HP-1s do pop up on the used market on occasion, so that might be a way to get one.
If you're looking for the DIY experience, I recommend building an HP-2. The HP-2 does provide lower output power than the HP-1. That's really the main difference between the two. The HP-2 has a better chassis design (both from an aesthetics point-of-view, and from a reliability point-of-view). I learned a lot about manufacturing between the HP-1 and the HP-2.
I have the HP-2 PCBs in stock. The chassis and PCB with SOICs pre-populated will be in stock tomorrow. The chassis are already here. I'm just waiting for shipping boxes for them.
Tom
If you're looking for the DIY experience, I recommend building an HP-2. The HP-2 does provide lower output power than the HP-1. That's really the main difference between the two. The HP-2 has a better chassis design (both from an aesthetics point-of-view, and from a reliability point-of-view). I learned a lot about manufacturing between the HP-1 and the HP-2.
I have the HP-2 PCBs in stock. The chassis and PCB with SOICs pre-populated will be in stock tomorrow. The chassis are already here. I'm just waiting for shipping boxes for them.
Tom
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