Neurochrome HP-1

He then made ODAC, which output surprise surprise 2V. Pretty much unity gain or 2X, or bust.

 

I have an O2 sitting on my kitchen table, fully charged. I will put it through the same set of measurements as I did with the HP-1 and QRV08. I also plan to run it at a decent output level into a resistive load and monitoring the DC output level as the rails collapse. That could be rather interesting. I suspect bad things could happen if one rail collapses before the other.

Anyway. This is a couple of weeks out. Back to the regular scheduled program. I'll start a thread on the O2 once I have data.

Tom

 

Sure thing. I've been very busy but was planning on doing a follow up with some comparisons with the B22, Klone and QRV-08, and detail some of my preferences and biases.

 

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.

YMMV.

 

It sounds like the HP-1 is "Molecular Gastronomy" kind of amp.

 

Here's my HF review: http://www.head-fi.org/t/830987/rev...-your-hd650-or-what-the-o2-wishes-it-could-be

 

To be fair, it's sort of a different philosophy. O2 was "How cheap can I make a DIY amp that measures (selectively) well" and the HP-1 is more of "How good can I make a DIY amp measure?"

Interesting to see a decisive split between opinions though.

 

The HP-1 would not be my first choice with the Utopia; I'd pick something a bit lazier.

 

Hello,

What is the power output to 600 ohms? I have a set of Beyer T1's.
Also what it the output impedance?

Thanks
Alex

 

I'm not surprised, the Utopia's tendency to be a bit strident up high is only heightened by a powerful SS amp, I'd imagine. I'd be shooting for a slightly euphoric texture-loving tube amp to play to its strengths.

Not sure what to say about the Elear though, that scooped-out tuning turns up everywhere. If it didn't have that, I'd own a pair already.

 

The published specs are 3.0W @ 32ohm and 450mW @ 300ohm.

Presumably the amp is voltage limited at the higher impedance loads, and we can simply divide by 2 to get 225mW @ 600 ohms.

I'm actually not sure about the output impedance, but we can wait for @tomchr to answer that.

 

450 mW into 300 ohms. Voltage matters more than power into high impedance loads.
The amplifier runs on +/- 18V rails, so I expect driving 600 ohms should be OK.
Full specs are on Tom's website http://www.neurochrome.com/hp-1-ultra-high-end-headphone-amp/.

 

Driving 600 Ω loads is no problem. 225 mW is a reasonable estimate of the output power into 600 Ω.

The output impedance is 0.5 Ω.

Tom