Neurochrome HP-1

tomchr · Jan 12, 2017

I know some of you earlier expressed some desire to know more about the circuit architecture. I was listening. It just took me a bit to get the block diagram drawn. Sorry about that. You'll find it below.

The output impedance is 500 mΩ (= 0.5 Ω).

Tom

tomchr · Jan 13, 2017

Measured the output power and THD into a 600 Ω load. Just before clipping, you're looking at 230 mW into 600 Ω. The THD measures 0.000017 % (-135 dB) at 200 mW into 600 Ω.

Tom

Armaegis · Jan 13, 2017

Hey @tomchr , any word on when you'll be able to do the O2 teardown?

tomchr · Jan 13, 2017

Hopefully before the end of the month. For sure not this weekend.

BMF Flyer · Jan 19, 2017

fishski13,

Awesome review and and a very entertaining, enjoyable read! You got chops.

All I can add is I like HP-1 very much and ordered the PCB and Chassis, inbound; BOM from mouser arrived yesterday. Let the building begin.

BMF

fishski13 said: ↑

When I was 14 years old I rented an acoustic guitar and checked out a Best of Bob Dylan vinyl box set from the public library. One of my most vivid childhood memories was dusting off my dad’s old hi-fi, setting it all up in my bedroom, and sitting on my bed spinning vinyl and spending hours and weeks teaching myself how to play guitar all through the hot, lazy summer between 8th and 9th grade. Even though I sucked, I was immersed, transported, and blissed out in a Joseph Campbell kind of way (I had discovered JC around this time as well). I was hooked on music and audio, and have been ever since.

While I think it’s lame that Bob Dylan received the NP for literature, he did arguably write the greatest song (not literature) of protest and of love, “Hurricane” and “Don’t Think Twice, It’s All Right”. I would also argue that in the modern pop genre, Katy Perry has written some pretty special love tunes in the voice of a young female that are infinitely smarter than BD’s ‘Lay Lady Lady”. I’m surprised a shit-kicking country-pop star like Toby Keith hasn’t covered this tune yet.

Let’s entertain a rhetorical thought experiment and imagine an alternate universe where our current laws of physics don’t exist, and there’s a perfect, uncolored chain of audio components/recording medium all way from the microphone that Bob Dylan sang into and out through our transducers. (My rigid adult mind tells me this is silly because this is impossible, but my 6 and 9 year old children, and probably even myself at the age of 14, would say why not imagine it). What would the songs and recording sound like? Would you feel transported to the event and into the recording studio? Would you hear the miking technique in pristine purity? Would you hear every detail? Would you be able to pick out whether or not BD was strumming a Gibson or Martin? Would BD’s voice be more or less nasally? Would you cry, develop Takotsubo, or be incited to walk in protest with BLM? Possibly, but it doesn’t matter, it would still be an illusion. Music playback is an illusion and no different than the illusions we experience in our own minds and within our own individual manicured and curated realities. As humans, we’ll interpret, create and make up shit in our heads anyways. The recording and performance event is dead, it’s a poor fossil that has been copied over and over on various playback mediums, and we’re left to muddle through the muck and mire of digging up the ‘true’ event with intelligent audio playback design and engineering.

Recorded music and audio playback is just modulated alternating electrical voltage/current, in other words, the AC mains voltage that comes out of your wall. This voltage/current doesn’t merely ‘power’ the magic in the audio circuits and transducers to create sounds and music. This voltage is modulated to DC that various passive and amplifying components can use to reconstruct an AC voltage that becomes the signal that moves the transducers, or is transferred to a recording medium. If we break down a basic energy transfer chain, the sun heats the earth, creates wind that drives windmills, which in turn spin some rocks dug out of the earth to create a electrical field and voltage/current potential to give us electricity to the outlets in our walls, which created and recreates the recorded voice and instruments of BD from a long time ago in a place far, far away...So when you’re listening to music in N. America, on a basic level, you’re just listening to the transformed 120VAC/60Hz pulsing through the copper wires in your walls.

No amplifier will please everyone, but synergy between components is an important consideration when evaluating expensive hi-fi gears to determine if they gel to meet a listener’s preferences. While I can say that the HP-1 pushes all the right buttons for me, I have other amps that would be more pleasing depending on one’s preferences.

I place value for money high on my list since I have other things that enrich my life and family that I would rather throw disposable income at. I was raised by a single working class father and as a consequence suffer from an ingrained guilt when spending money on selfish pleasure. I’m also not interested in riding the audiophile carousel and tend to hold on to a component for long period of time after making the decision to buy/build it.

As far as my audio reproduction preferences, I place a greater emphasis on the ‘musical line’, or the ability to render a musically satisfying experience, rather than a strictly ‘hi-fi’ experience. What I mean is that I don’t care if I can hear BD pass gas, the squeak of a drummer’s stool, whether a violinist is fiddling on a Strad or not, or if the entire band perfectly placed in a perfect soundstage. If it’s musically uninvolving, I’d rather watch Netflix or a concert on the television. If I can get the hi-fi along with a musically satisfy experience, then I’m tickled. While both are not mutually exclusive, I think there are some trade-offs – if I’m constantly being drawn to analyzing the hi-fi, I’m missing the music. I don’t mean to sound pretentious in my black turtleneck, black beret, while puffing on a Gauloise and shouting “To Music” in between existential arguments with myself. We can all rock on different porches. To each his/her own in finding audio/music bliss.

I ‘joined’ an audio cult 15 years ago, buying a Naim Audio speaker rig, Grados, and a TT, genuflecting to the Church of Flat Earth. No matter what pew row you sat in, if playback didn’t have a toe tapping PRaTty presentation, it was rejected. Saying something like, “That’s so hi-fi”, would be considered an insult toward the playback gears in question. In contrast, The Round Earther, or ‘Roundies’, were so boring pipe and slippers heretics focusing on ‘hi-fi’ and things like soundstage, tone, and details above all else. Thanks to Ivor Tiefenbrun, Roundies were roundly accused of sporting mullets, short in the front and long in the back, with a greater emphasis on transducers rather than the source.

In time, after spending $10K on my personal Flat Earth shrine and multiple ‘upgrades’ here and there, I realized I wasn’t happy with the sonics. The rig excelled at timing and tuneful dynamics, but was often at times harsh, thin, dry and would occasionally strip paint off my walls. I had only a small handful of recordings that would sound decent even after careful room treatments. I was told to spend more money in the vein of Scientology to attain higher levels of audio bliss. I wanted more ‘hi-fi’ and value for my money so I bought a Benchmark DAC1 that was all the rage back then. Then after getting boned on a DIN-RCA cable job from my dealer in order to connect the DAC1 to my Naim preamp, I woke up and sold it all off in short order, but kept the DAC1. I moved on, bought some Krell, ATC, and then in time discovered DIY, Nelson Pass, a bunch of great headphone DIY designers, lots of cool headphones, and full range drivers. Fast forward to today, I don’t listen to speakers much. I still have an unfinished speaker project I’ll get around to some day, but for right now in my life, I love the simplicity of headphones.

Tonally, the HP-1 is the most colorful sand amp I’ve heard. It makes every other sand amps sound a little dry and gray. In my rig, it sounds juicy and tasty. I like how tonal details, transients, and timbre are rendered. You can clearly hear when a note starts and stops. Like I said before, I feel like I can hear the fundamental of the note more easily. It’s cool when Dave Holland’s bass hits the same note as Robin Eubank’s trombone on the album Extended Play: Live at Birdland, and you feel like you never heard that note before, and how they sound more in tune with one another. This album is on my greatest hits and reference recordings list. I’ve listened to this amazing album countless times and like how I’m experiencing it in a different way with the HP-1.

Dynamically, the HP-1 propels the music forward in a very muscular way. It times and captures the emotional musical interplay between members of a band like a champ. Guitar riffs sound more ‘riffy’ because I hear a greater difference between sound levels and impact of each plucked note. A tasty subtle drumming style like Jim Hodder sounds more tasty.

Let’s talk about what the HP-1 doesn't do well: soundstage. Voices and instruments don’t have the height and depth that the B22/M3 and Klone can do. These amps are better able to transport you to a live venue. It’s a compact more L to R soundstage. While it has great sound localization, it doesn’t have a big, airy presentation. This isn't the least bit bothersome for myself. If you want the audible illusion of Katy Perry walking towards you to give you a lap dance, look elsewhere.

Also, I guess the HP-1 could come across as fatiguing and unrelenting, not in a frequency related trouble with trebles kind of way, but rather someone may prefer a relaxing musical presentation. You might find your downtempo electronica like Kruder & Dorfmeister sounding a bit more uptempo. It was impossible for me to do anything other than listen to music when listening with the HP-1. I had to switch it up to the Klone when I started typing this review yesterday. If you prefer a more relaxed presentation, you might find the HP-1 unnatural, and likening the presentation as tasting like MSG. I wouldn’t agree, but then I again I’m probably rocking on a different porch.

With DIY, you may have variability in sound sigs between two different amplifiers of the same design. I hear differences in pots and attenuators. I wish I didn’t. Spending $250 on the 47-step GoldPoint attenuator in my Klone hurt me. I prefer GoldPoint attenuators or TKD pots. I have no plans on changing the stock pot in my HP-1 build though. Also, the bias of the output devices can alter the sound a little as well. Take everything below with a huge pile of sand.

I love my B22 and M3 to bits. Each are a little different from one another, and depending on which opamp you use in the M3. These pair great with my modded AKG K7xx series. I think both could be considered on the warm side of neutral – a higher bias on the output MOSFETs can add a bit more. The B22 is the perfect amp with the AKGs if I just want to sit back, chillax, and have the music flow over you. In addition to monkeying around with the bias, with the M3 you can change up the sonics by rolling opamps. Everyone who ever asked me to build a B22, I would recommend the M3 first due to it’s sonic flexibility if they didn’t need the V swing of the B22. No one ever took my recommendation.

My Klone is a great pairing with my HD600. If firms and cleans up some of the Senns sleepy, smooth, soft characteristics. The Klone has a slightly more forward soundstage compared to the more grandiose cathedral-like B22, and an over all leaner tone compared to all of my other amps. It highlights the transients and note attack over body - rosin and strings are highlighted over the wood body of a violin. I think resolution is top notch and dynamically close to the HP-1, but lacking in the last bit of M factor.

The poor QRV-08 that everyone thinks is a POS. I prefer it with the K7xx series and the Oppo PM-3. While it’s lacking in ultimate resolution, tone, soundstage, and larger scale dynamics, it lightning quick, has nice texture with acoustic instruments, and is musically satisfying.
Click to expand...

fishski13 · Jan 23, 2017

Tom was nice enough to send me another HP-1 to bring to the upcoming HF ChiUniFi meet. The chassis does look much better in real life and I actually quite like it after the initial shock of seeing the pictures on-line. It’s a deeper blue, like Grover from Sesame Street, rather than Thomas the Train blue. Attached below is a crappy pic from my Samsung S6. The physical size is not much deeper than my Oppo HA-2, and not much taller than my Garmin watch. I liked the amber color of my Old Fashioned next to the amp and am going to go with a diffuse amber LED. The blue LED looks great though and has to be the only blue LED in existence that doesn't burn your corneas.

I've done my fair share of chassis building and design. If I wanted a more traditional aesthetic, I would go with a Lansing chassis, spend hours designing on FPE, measuring every chassis-mount component with a micrometer (relying on datasheets alone is too sketchy), and after calculating shipping from Lansing, and to and from FPE, I'd still be spending around the same as the stock chassis. Also, with the stock chassis, there's no drilling, mounting chassis-mount components, and no air-wiring. Stuffing boards is the easy part of DIY - chassis design, layout, mounting, and drilling out can be a chore. I really like the smaller form factor that I wouldn't be able to get with an off-the-shelf chassis. Besides, I'm still kind of burned out on chassis design going back to my SWA years. I've cut out more IEC D-holes than I care to remember. Choose your own adventure.

I popped the lid off the HP-1 for a closer inspection. This is not a project for a first time DIYer. If you have experience with SMD, then you're probably good to go assuming you have a decent iron, tweezers, flux, solder braid, and 0.015" solder. If you're new to SMD, and you need a USB scrubber, the Doodlebug from Beezar would make the perfect first project before tackling the HP-1 (the Doodlebug kicks ass btw). While not as difficult as the QRV-08, the HP-1 is a fairly labor intensive stuff job, but very neatly laid out and shouldn't give anyone too much grief. Tom also has a great article on choosing solder on his website. I've gone ahead and ordered all RMA solder, flux, and solder braid. No more silver bearing solder for me with routine SMD. There are no silver plated components in the HP-1 anyways. I hope to get soldering in a couple of weeks. Also, the HP-1 documentation is great.

Jh4db536 · Jan 23, 2017

Here's some more pics of the "Netgear amp".
It's going out on loaner next week so more people can hear it.

Chassis design is definitely time consuming and usually takes me longer than getting raw parts to functionality. I had this thing done in two weekends by Xmas break although chassis less on my rack.

I usually use green LED on my builds

tomchr · Jan 23, 2017

One of my electronics instructors used to say that the chassis was the last 10 % of the project that took the last 90 % of the time.

One can get a custom chassis done - as I did - and if you have the right tools, that can certainly be a fun side project. For reference, getting one HP-1 chassis made will set you back well over $300 (USD) if you order it directly from the manufacturer at QTY = 1. I had to order a pretty good stack of them to bring the price down to a more reasonable level. The side profiles are extruded. I think the panels are laser cut. Either that or water jet. I like the way they turned out, though I will openly admit that I was biting my finger nails a bit as I handed over the credit card number...

Tom

Kattefjaes · Jan 23, 2017

tomchr said: ↑

I like the way they turned out, though I will openly admit that I was biting my finger nails a bit as I handed over the credit card number...
Click to expand...

Having seen a few more action shots, it looks nicely understated and bombproof. If I was being picky, I'd have chosen a slightly plainer sans serif typeface, but at least that's mostly on the back. For such an aggressively functional design, it looks pretty cool. Are you glad that you took the plunge and had a "proper" case made?

ultrabike · Jan 23, 2017

I want black. Why is it not black? Black.

I actually like the Schiit or the HeadAmp chassy types. But black.

We'll see how this ones looks live. But it's already not black.

(EDIT: BTW kidding. I like black, but who cares)

bazelio · Jan 23, 2017

Mine is black.....

Muuuuuahahaha!!

tomchr · Jan 23, 2017

The amp was demoed and the feedback I got was "why's it black? Black's boring! We want colour!" So I made it blue.

I can get the next stack of enclosures in a variety of colours for not that much extra. The manufacturer offers a pretty nice Carmine Red (RAL3002) along with black and the RAL5010 blue I'm currently using. Maybe a couple of the red and a 50/50 split between blue and black for the rest. See what sells. I s'pose I could also get a survey going.

I would prefer to only stock one colour.

Tom

tomchr · Jan 23, 2017

Kattefjaes said: ↑

Having seen a few more action shots, it looks nicely understated and bombproof. If I was being picky, I'd have chosen a slightly plainer sans serif typeface, but at least that's mostly on the back. For such an aggressively functional design, it looks pretty cool. Are you glad that you took the plunge and had a "proper" case made?
Click to expand...

I'll probably change the font to a sans serif type for the next batch. The serif font is just a tad thin and doesn't work so well with the texture of the powder coat. It looks nice, though. I don't want the lettering to be too big. Just big enough.

I like the HP-1 and am glad I took the plunge with a real chassis. It's a real project and a real product. Not that my other circuits or products aren't real. They very much are. It's just really nice to take a project from concept to finished product. It seems quite a few builders agree with me and have built theirs already, which is really nice to see. Thanks.

Tom

ultrabike · Jan 23, 2017

tomchr said: ↑

The amp was demoed and the feedback I got was "why's it black? Black's boring! We want colour!" So I made it blue.

I can get the next stack of enclosures in a variety of colours for not that much extra. The manufacturer offers a pretty nice Carmine Red (RAL3002) along with black and the RAL5010 blue I'm currently using. Maybe a couple of the red and a 50/50 split between blue and black for the rest. See what sells. I s'pose I could also get a survey going.

I would prefer to only stock one colour.

Tom
Click to expand...

Nah man. f**k them. Use the colors you like.

(like black)

ultrabike · Jan 23, 2017

I mean look at Donald North. Blue all the way baby.

Schiit. Who cares about the color. Shiny and iMac like.

tomchr · Jan 23, 2017

Oh, yeah. If I could get a brushed aluminum finish with a clear anode from this manufacturer I totally would.

Tom

ultrabike · Jan 23, 2017

tomchr said: ↑

Oh, yeah. If I could get a brushed aluminum finish with a clear anode from this manufacturer I totally would.

Tom
Click to expand...

Didn't mean to push any direction. Meant to say that whatever you choose is fine. It's your product. And as such it should have it's own unique look and feel.

tomchr · Jan 23, 2017

What I do want is actually that brushed aluminum look. Maybe anodized. Nicer than Schiit. If I ever go that route, I'll need to work with a different manufacturer. I'd probably also set up a different website for the finished products (to keep them separate from the DIY side of things) and charge 2-3 times as much. Ah... So many projects. So little time.

Tom

ultrabike · Jan 23, 2017

Well I'm not the one to talk about DIY and audio products. Because I have not made anything, yet.

But you can see some of the items Head-Amp sells. In terms of looks, they are pure and simple sex:

http://www.headamp.com/product-category/amplifiers/

I think however that as price goes up, volume sales go down.

tomchr · Jan 23, 2017

ultrabike said: ↑

But you can see some of the items Head-Amp sells. In terms of looks, they are pure and simple sex:

http://www.headamp.com/product-category/amplifiers/

I think however that as price goes up, volume sales go down.
Click to expand...

Not bad. As far as price vs sales volume goes, that depends on the elasticity of the supply/demand curve. I'd rather sell a few a year and make, say, $2000/each in profit than sell 200 at $1 profit each. I deliver high end performance and should charge accordingly. I'm in a low volume, high margin business. If you want high volume, low margin, there are plenty of vendors on eBay...

Tom

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