[Armaegis]

The HP-1 is an amazing amplifier. It absolutely smokes the O2.

Clearly the best solution is to just get *all* the amps and write down some impressions for us 

[adydula]

I need to start a go-fund me page!!

Do you have an HP1??
Would be interested in a real world comparision sonically.

Specs are one thing and the HP1 has great specs for sure!!

Alex

[dB Cooper]

The HP-1 is an amazing amplifier. It absolutely smokes the O2.

For eight times the price, it damn well better.

[adydula]

Something tells me its not 8 times better than an O2....not saying its not a great amp, I firmly believe that the difference is most likely not "spectacular".....

I have listened to many amps costing as much as the HP1 and none of them are worth the extra cost for the somewhat intangible gains.

But I am respectful of the HP1 and its designer to get an amp working with these stellar specs and results.

Just wish it didnt cost as much....but thats the way it is.

Alex

[Armaegis]

This entire hobby is a horrible game of diminishing returns. Is the O2 five times better than my cmoy? Is the HP-1 twenty times better than my opamp+buffer (it even has a servo!) in a tin can that I designed and built myself? For that matter, I prefer to run my headphones straight from the jack of my Sansa Fuze that I picked up used from the local classifieds for $10 almost a decade ago. Using separate amps for headphones? That's just crazy talk!



(says the guy with monoblock headphone amps in the corner...)

[adydula]

I can understand that....

I have used the outputs of many devices, from AVA preamps, Sony, Onkyo, Denon, Yamaha AVR's etc and they indeed to work, depending on the cans and the impedance and sensitivity. There are indeed differences...but at what cost.

For many of us wierd folks, like me, I enjoy the building and circuitry etc so its not crazy to us its a pastime and rewarding hobby.

The part is we just dont blindly go into a store and buy something and become an appliance operator, but hey thats fine as well.

Many appliance operators often after a few weeks of listening come around and start asking questions about what they bought good or bad.

I recently got a new laptop and tried listening to music from its audio out jack with its internal dac/amp...and I was really amazed at how
good the sound was! Its excellent with my T90's but with the T1's its not as excellent IMO.

Diminishing returns me thinks so as well, searching for perfection in a circuit whether you can hear it or not....priceless...lol!~

Alex

[dB Cooper]

I am an audiophile, which to me means someone interested in the science and art of recording and reproducing music in as lifelike a fashion as possible.

But...

At some times it just behooves one to fire up their system (speaker, headphone, or either depending) and dig some tunes. Forget about whether your system delivers the PRaT you paid $20K for, or whether whatever shortcoming you perceive is worth another round of upgraditis, and just roll with what you've got. I don't want to fall into this trap, which like probably all of us I have from time to time:

[adydula]

AGDR has decided to retire the ODA design for several reasons:

From AGDR:
BTW- hearing that tomchr's HP-1 uses a pot in the middle I've officially "retired" my ODA design out on my website (in another thread here) and have put in a link and suggestion to look at his HP-1 instead.   tomchr's HP-1 sounds like a more modern design and has the objective testing with a "real" tester that was the whole point of NwAvGuy's O2 and his mentioned but never-released ODA (O2 Desktop Amplifer). The AC-AC wall transformer my version of the ODA (and NwAvGuy's O2!) is designed for is nearly un-obtainable now, as is the discontinued LME49990 chip. I put a clipping detector in the ODA to solve that VAS stage potential for clipping-without-notification in the O2, but Tom's solution is even better, use higher voltage power rails. I couldn't do that with the ODA given the 3 parallel SIP NJM4556A chips on each channel. They have high idle current resulting in large idle package dissipation at even +/-15Vdc rails with no way to heat sink, hence the standard +/-12.5Vdc rails. tomchr: excellent work on your HP-1 design, IMHO!

The HP1 seems to be to latest and greatest spec wise....it costs about the same as the ODA if you DIY it. But due to parts for the ODA not being available anymore and Tom's design is even a better design...

That said the ODA is still a really good headphone amp and now will become a rare entity!

Alex

[Armaegis]

For those curious, Tom recently purchased an O2 (from JDS labs) and ran it through his testing regimen...
http://www.neurochrome.com/o2-headphone-amp/

[adydula]

You might want to put this information about the O2 in a seperate thread to giver it more visability....I think many people will find this interesting....IMO.

Also AGDR is thinking of sending his O2 Booster board to Tom for analysis!

Alex

[dB Cooper]

As a (very satisfied) owner of a 'boosterized' O2, I'd be interested in seeing that. agdr, if you do this, I'd suggest supplying a 'true-zero' output impedance version.

Note that I consider 0.0014% IMD ( ~ -119dB), cited as a 'weak point' in the stock O2, to be acceptable.  The O2 is 'the amp everybody loves to hate', perhaps because it outplayed many more expensive competitors when it was introduced and forced many in the industry to be more transparent about their performance, made it harder to justify expensive 'meh'-performing amps, and raised awareness of what makes an amp a good amp.

The emphasis in the review seems to be on the O2 as a portable. The O2 is not a great portable IMO. Most of the mechanical and electrical compromises in the design seem to stem from the design constraint of portability and the heavy, bulky NiCD 9V batteries used. The review largely seems to agree. Mine has never had batteries in it, and sits on my desk, so my PCB has never rattled. I personally think portability is the Achilles heel of the O2 and that NWAVGuy would have been wiser to do a desktop-only design. As far as output power, even the stock 02 plays my 300 ohm Hd650's (the headphone everyone loves to hate) loud as hell. Why pay extra for the ability to inflict hearing damage.

If the O2 fades away due to unavailable power supplies (really, thats the only 12VAC brick in existence?), the Schiit Modi is probably a respectable alternative for us C&C'ers.

[Armaegis]

You might want to put this information about the O2 in a seperate thread to giver it more visability....I think many people will find this interesting....IMO.

Also AGDR is thinking of sending his O2 Booster board to Tom for analysis!

Alex

I have a review of the HP-1 posted up at head-fi. I was thinking to copy over the table comparing the specs, but the formatting is all butchered when I bring it over. When I get some time I'll take a screenshot or try to make another table over here. In the meantime, here's a link to the comparison:

http://www.head-fi.org/t/830987/review-neurochrome-hp-1-making-sweet-love-to-your-hd650-or-what-the-o2-wishes-it-could-be/30#post_13209005

[adydula]

I agree the O2 is indeed the amp to hate!! The whole experience made many oems toe the line, start posting specs, impedance in and out etc....and for the price of admission its a great head amp for sure.

I am torn with building the HP1, just because! I dont think the price differential will equate in that big of a sonic difference, but I would like to see this for myself....we shall see. 

Alex

[dB Cooper]

I agree the O2 is indeed the amp to hate!! The whole experience made many oems toe the line, start posting specs, impedance in and out etc....and for the price of admission its a great head amp for sure.

I am torn with building the HP1, just because! I dont think the price differential will equate in that big of a sonic difference, but I would like to see this for myself....we shall see. 

Alex

To reiterate a point I made earlier, the HP1 better outperform the O2... for eight times the price.

The point neurochrome made about the O2 being represented as a 'state of the art' headphone amp is, with all due respect, off base IMHO. I don't think the O2 was represented as a SOTA design per se, but as a high performing amp, that would drive most headphones, at a price even non-audiophiles wouldn't consider ridiculous. I think it largely succeeded. It's amazing how many 'night and day' differences become undetectable in blind listening comparisons.

[adydula]

My ODA is now "3" years old and I use it almost everyday.

Never had any issues with it. I have a small preamp chip wired in it (one of the many optional things you can do with AGDR's ODA) to allow my small modified
Pioneer desktop speakers to play computer sounds, music etc...via a ONKYO AVR.

Since then I have built many DIY amp circuits, including the O2, O2 Booster Board, O2 with OP1688's, Super Cmoy amps with the new TI chips designed just for headphone amps.
I also built a Bottlehead Crack with Speedball, a recently added Schitt Vahalla 2 OTL etc...

I also upgraded from my many cans to a set of 2nd gen T1's.

Over the last few weeks I lined them all up and started to do some comparisons....mostly subjective vs the objective side of me.

Last night for the first time I stuck the T1's into the ODA and was floored how good the sound was.

Its better IMO than the new Schitt Vahalla 2, the Bottlehead Crack, the O2's and Cmoys..absolutely amazing what this amp and the new T1's sound like.

I went back again and again with the Schitt V2, and Bottlehead and O2's....each time my brain is telling me now that this amp and the T1's are very, very good.

Going thru most of my demo material the vocals pop out and your in the room, all those adjectives about, hearing things you never heard before apply.

The soundstage was wide, presentation was awesome..I cant think it can get any better...when I stop listening to the equipment and listen to the music...this is a good thing!

I rate then like this: ODA with T1's : 9   Schitt Vahalla 2: 8+    Bottlehead Crack: 7.5
The O2 versions: 8.

...and I have (2) more DIY's in the fire!! I doubt that they will be sonically any better than the ODA and the T1 combination...so why go there??

Because I like soldering!!! (ha!)

Alex

[Rocket]

Hi Alex,

Thank you for your post.  I sure wish I was good at diy and I feel a bit envious of your skills.

Cheers rod

[adydula]

Good Morning Rod!

Just saw your note, I grew up in the electronics industry as a electronics technician, debugging, calibrating all kinds of electrical equipment. I learned to solder at IBM repairing circuit boards...lots of mistakes and burnt finger tips!! I learned about solder wick, flux, etc....then on to Oscilloscopes, high end digital o'scopes and other strange and exotic equipment.

Most of the DIY stuff is fairly sane if you know how to solder and have some common sense. I still take these DIY things very slow for the most part, study the circuit, make sure the parts are correct before installing and make sure they go into the right places!! I print out the schematic and use it as an install guide, and before applying power I usually check out the power supplies on the circuit board for proper operation before hooking them up to all the downstream circuits....

I have two more DIY headphone amps in the planning stages! Ha!....There is a fellow in France that has used the latest op amps and parts designed just for headphone amps, imagine that, in a new test amplifier. I have the pcb and most of the parts but the parts are SO dang small, I am wondering how to pull this one off!!! I have to learn how to hot air solder and or a reflow oven process. I bought a low dollar chinese made hot air gun on eBay and instead of using normal solder, I have to use a solderpaste, place the tiny part , then heat it up with a hot air gun and then hope the part is soldered and not fried!!

The second project is one thats called the "crocodile", designed by a great DIY's over at diyaudio, Sergey888, in Australia. He is a perfectionist and genius, much like Tom the designer of the HP1, its using the new TI headphone parts to get the best performance out of them, ie extremely low distortion specs etc....Same very small parts....this one is a month away.

So now with 9+ amps here, I can easily test, listen and compare lots of stuff and instead of relying on online reviews etc...I can hear or not hear for myself what folks are saying about these amps and verify the many,many comments!!

After all this building I often just tell myself you have as good as it gets out there sonically, so just stop building and listen! Ha! ....but that would'nt be any fun!

All the best
Alex

[jtwrace]

Good Morning Rod!

Just saw your note, I grew up in the electronics industry as a electronics technician, debugging, calibrating all kinds of electrical equipment. I learned to solder at IBM repairing circuit boards...lots of mistakes and burnt finger tips!! I learned about solder wick, flux, etc....then on to Oscilloscopes, high end digital o'scopes and other strange and exotic equipment.

Most of the DIY stuff is fairly sane if you know how to solder and have some common sense. I still take these DIY things very slow for the most part, study the circuit, make sure the parts are correct before installing and make sure they go into the right places!! I print out the schematic and use it as an install guide, and before applying power I usually check out the power supplies on the circuit board for proper operation before hooking them up to all the downstream circuits....

I have two more DIY headphone amps in the planning stages! Ha!....There is a fellow in France that has used the latest op amps and parts designed just for headphone amps, imagine that, in a new test amplifier. I have the pcb and most of the parts but the parts are SO dang small, I am wondering how to pull this one off!!! I have to learn how to hot air solder and or a reflow oven process. I bought a low dollar chinese made hot air gun on eBay and instead of using normal solder, I have to use a solderpaste, place the tiny part , then heat it up with a hot air gun and then hope the part is soldered and not fried!!

The second project is one thats called the "crocodile", designed by a great DIY's over at diyaudio, Sergey888, in Australia. He is a perfectionist and genius, much like Tom the designer of the HP1, its using the new TI headphone parts to get the best performance out of them, ie extremely low distortion specs etc....Same very small parts....this one is a month away.

So now with 9+ amps here, I can easily test, listen and compare lots of stuff and instead of relying on online reviews etc...I can hear or not hear for myself what folks are saying about these amps and verify the many,many comments!!

After all this building I often just tell myself you have as good as it gets out there sonically, so just stop building and listen! Ha! ....but that would'nt be any fun!

All the best
Alex

Are there any measurements of the Crocodile like there are of the HP-1? 

https://www.neurochrome.com/hp-1-ultra-high-end-headphone-amp/

https://www.neurochrome.com/product/hp-1-ultra-high-end-headphone-amp/

[adydula]

Not that I am aware of....here is the thread that has some distortion plots:

http://www.diyaudio.com/forums/headphone-systems/270294-crocodile.html

Alex