Neurochrome HP-1

Size Queen Gilberto

 

You guys are both big knobs.

 

Neurochrome HP-1 Headphone Amplifier
Build: February 2017
BMF Flyer





Prelude

I like a lot of different amps. I enjoy building DIY amps and it’s fun “rolling” amps, so to speak…solid state, all tube, and hybrids. So, which one sounds best? Well, for me it depends… on the day, the music genre, the mood, the quality of the recording, and the headphones to mention just a few of the variables involved in producing “sound quality” and audio pleasure.

What one person hears and describes may be heard and described very differently by others. Objective measurements can help but don’t guarantee you’ll like what you hear. It comes down to opinions, personal preferences and simply, “what sounds good, sounds good.”

I had the opportunity to participate in SBAF’s Neurochrome HP-1 tour. Before my week HP-1 was up, I knew I wanted to build one. I ordered the PCB, custom enclosure, volume knob, and RCA jacks from Tom Christiansen, an electrical engineer and designer of HP-1. The HP-1 components arrived within a few days of receiving the BOM from mouser.com I had ample time to sort and label all parts corresponding to Tom’s excellent build guide and BOM. I completed my HP-1 build over the course of two weekends. I really took my time and proceeded carefully. I double-checked each component against the BOM and schematic and measured each and every one both before and after soldering them in place. Patience and attention to details paid off…when I flicked the On switch, the soft blue LED lit up…and there was no smoke! I ran it through the setup and testing procedure recommended by Tom. The DMM showed 200 mW RMS and 0.00 VDC offset on the outputs. OK, time to take HP-1 for a test drive.


Gear Chain

Lossless and FLAC files > iMac 7 > OPPO HA-1 DAC > HP-1 > HD-650, HD-600, AKG 7xx, Beyer 990, OPPO PM-1 and PM3, Yamaha YHD-1


“A Few” Eclectic Test Tunes I know very well. These tunes put amps through their paces demanding rendition of complex bass, sweet acoustic/vocal mids, and treble details:

Anna Maria Jopek and Pat Metheny – Are You Going With Me?
Beck – Blackbird Chain
Bill Evans – Piece Peace
Cake – I Will Survive
Charlie Hunter Trio – Wizard Sleeve
Donald Fagen – Maxine
Gorillaz – Dare
John Mayer – Slow Dancing in a Burning Room
Jon McConnell – Sober
kd lang – Save Me
Smetana – Ma Vlast mvt II
Shostakovich Symphony No 5 mvt iv
Lucinda Williams – Essence
Mana – Mariposa Traicionera
Marcus Miller – Redemption
Metallica – Whiskey in the Jar
Miles Davis – So What
Muse – Hysteria
Norah Jones – I Wouldn’t Need You
Patricia Barber – Too Rich for my Blood
Perlman – Bach Double Violin Concerto
Punch Brothers – Missy
Radiohead – Jigsaw Falling Into Place
Steely Dan – Babylon Sisters
The Tao of Groove – Multatica Mia
Vlatko Stefanovski & Miroslav Tadic – Kajesh Anjo
Willie Nelson – Vous et Moi
Wynton Marsalis – The Magic Hour
Yes – Long Distance Runaround
Yo-Yo Ma – Quarter Chicken Dark


Impressions

The background is Black and dead quiet. There’s no hum, buzz, or other noises when not playing music, and none during silent passages of songs at any volume pot setting. I agree with Tom, Armaegis, fishski13, and others that HP-1 is “a straight wire with gain.” Parsimony Rules: HP-1 delivers a flat FR. No part of the FR is emphasized or cheated. HP-1 is balanced from bass, through the midrange, and into the higher frequencies.

Bass is fast, textured, and well extended. I really like how HP-1 “does” acoustic double bass harmonic layering and decay. Kick drums have punch. Tympanis have authority.

The midrange is fantastic and neither forward nor recessed. Vocals and acoustic instruments sound beautifully rich while remaining clear. I love HP-1’s rendition of jazz trumpet, tenor sax, and female vocals.

HP-1’s treble extends into the upper frequencies providing accurate micro details, “air,” and shimmer without any sibilance or pierce. Harmonics from chimes, triangles, and cymbals add sparkle and nuance to the sound quality. Hearing female singers inhale between phrases and the delicate sound of exhaling on the extended final syllable of the last word enhances the emotional impact of the song.

The width of soundstage and instrument placement is in the Goldilocks Zone…not too narrow, not too wide…just right.


Conclusions

Previously, I thought there was no discernable difference between HP-1 and QRV-08. After spending a good deal of time with them head-to-head using a Quick Switch adapter and SPL matching, I have concluded that there is a noticeable difference. HP-1 is rather more resolving, cleaner, and more enjoyable. I can voice this opinion with some authority given I’ve built 3 QRV-08’s And I really do like QRV-08…it’s no slouch to my ears and I like it a lot! It’s just that HP-1 ups the ante. HP-1 also competes with other amps I’ve auditioned, own, and/or have built including, in no particular order:

GS-X mkII
Liquid Carbon
OPPO HA-1
EHHA Rev A
CK2III
Bijou
Kameleon v2
Single Power MPX3
Some other TOTL amps


Finale

I had a lot of fun building HP-1. I’m having more fun listening with HP-1. Many thanks to Tom for creating HP-1, as well as a bit of technical assistance…he’s “on it!”

 

Thank you for taking the time to write a thorough review. I really appreciate it. I'm glad the HP-1 came together nicely for you.

Thanks for your kind words.

Tom

PS: I have opened up for reviews on my website. I was wondering why I wasn't getting any reviews. It turned out the ability to leave one was turned off by default (DOH!). That's now fixed. Verified buyers are now able to log in and comment. I'd greatly appreciate those who've bought and assembled the boards drop a line about your experience and results. Thanks in advance.

 

Sorry, but what's the link, again, for reviews?

 

You should be able to log into my website (www.neurochrome.com - "My Account" in the bottom left) and leave a review. If you can't, toss me an email.
Here's a direct link to the login screen: https://www.neurochrome.com/my-account/

Tom

 

Thanks, ultrabike. I started the DIY amp journey a couple of years ago thanks to dBel84. It's still a ton o' fun!

Tom made a slam dunk on HP-1.

 

Can find my review of the Neurochrome HP-1 here:

http://www.verumsonus.com/neurochrome-hp-1-review/

 

Very cool. Thanks for writing. I hope I by posting measurements will instil confidence in my designs rather than divide groups of people. While I'm openly an objectivist I do recognize that music reproduction has a subjective component to it that needs to be considered as well. I aim to make most people happy most of the time. There will always be some who'll want something slightly different. I'm at peace with that.

Tom

 

Is an assembly manual provided for construction?

Also, what is the total build cost with the blue chassis if you go the 100% DIY route?

 

You should get a manual after ordring.

It says here the BOM is about $250 (scroll down about a quarter page)... https://www.neurochrome.com/hp-1-ultra-high-end-headphone-amp/
plus the board and chassis are another $500, so that brings you to $750 total if you do the rest of the work yourself.

 

It says here the BOM is about $250 (scroll down about a quarter page)... https://www.neurochrome.com/hp-1-ultra-high-end-headphone-amp/
plus the board and chassis are another $500, so that brings you to $750 total if you do the rest of the work yourself.[/QUOTE]

Armaegis is correct on the BOM cost.

Keep in mind that you can often order 10, or in some cases 100, of a part and actually pay less than you would by buying the minimum number of bits called for in the BOM. This not only saves you a few dollars but also provides extras in case you lose or destroy one/some.

 

Unless you butterfinger the opening of a roll of tiny SMD components and send the whole package scattering to the wind...

 

My carpet most likely has more parts than some Pass amps.

 

Switching back and forth between RCAs and Balanced Inputs I don't hear a sound quality difference. What I do hear is a bit more SPL with balanced cables In.

I wonder what others hear.

 

Armaegis,

I have to admit that I've been guilty of butterfingers when opening those strips of SMD resistors and caps!

 

Testing the amp with the SE inputs as opposed to the balanced which I believe are summed at the input I'm finding this amp to perform much better. Issues with dynamics, low level detail retrieval and brittleness in the treble seem to improve significantly. Still maintaining a somewhat flatter sound with great clarity, I suggest using the SE inputs on this amp.

 

One time I had one component that popped out of my tweezers and bounced on my table. I reflexively tried to catch it... and smacked the strip near the table edge and sent the rest of them flying. I didn't even catch the first one