Tom Christiansen Audio HPA-1 Update

poseidonsvoice · « **Reply #40 on:** 19 Feb 2020, 03:55 pm »

Quote from: adydula on 19 Feb 2020, 02:32 pm

Wonder how the audio quality would compare to the DIY only HP2?

Alex

Alex,

I've listened to both but not in the same system/context.

All I can say is that there is a family resemblance to all of Tom's headphone designs. I listened to the Tom Christiansen Audio HPA-1 for quite a while at the Florida Audio Expo. The TCA HPA-1 forges ahead on tougher loads (i.e. 32 ohms and lower) and at higher power levels than the Neurochrome HP2. Otherwise, the Neurochrome HP2 I heard was sublime. I am not surprised though. Tom Christiansen has a baseline minimum standard design metric he must meet or else the product won't make it to market. It's in the Tom Christiansen psyche.

I have yet to finish building my Neurochrome HP2, but I am taking pictures systematically to show how to populate the board, assemble the enclosure, etc...

I plan on posting it on this subforum for those who want to read it. I also plan on comparing it to the Orchard Audio Pecan Pi DAC/headphone amp, as well as a few high end spreads if I can get my buddies to collaborate since they have them.

Best,
Anand.

adydula · « **Reply #41 on:** 20 Feb 2020, 01:04 pm »

Anand.

Please start a thread for the HP2 DIY build!

It would be interesting to see how its going and I just might come on board and do a build as well in the future...

I have a lot of stuff coming in in the next few months for comparison etc so my time is getting squeezed abit for DOY projects....but I do like them!

Thanks for the updates!
Alex

tomchr · « **Reply #42 on:** 20 Feb 2020, 06:46 pm »

Those interested in what the HPA-1 looks like on the inside, see below:

Home Theater Hifi awarded the TCA HPA-1 Best of Show for the Florida Audio Expo. You can read more here: https://hometheaterhifi.com/features/show-reports-film-festivals-concerts/florida-audio-expo-2020-coverage/

I have plenty HPA-1 in stock and available for immediate shipment.

I do agree that the HPA-1 name is not unique. If you google "HPA-1 headphone amplifier" you'll find Nelson Pass's headphone amp. If you google "HPA-1 headphone amplifier -Pass", you'll find mine. There are several other HPA-1 headphone amps. I'm not overly concerned about the naming conflicts.
I did consider a more unique naming scheme, but decided against it as I didn't think they'd offer any better connection with the amp than a generic name. Also, after a while you run out of Nordic gods, local mountains and rivers, and whatnot anyway. That reminds me of when I worked for National Semiconductor where one of the product groups would name their projects after local rivers. This was going well until they reached the Nooksack river. Apparently that was deemed an inappropriate name and projects were given generic names from that point on.

Tom

dburna · « **Reply #43 on:** 20 Feb 2020, 07:28 pm »

Stellar build, Tom, and the sonic accolades for this are growing. Frankly, you could name this one Nooksack and it would still be a hit.

Keep on doing that voodoo that you do so well, -dGB

timind · « **Reply #44 on:** 20 Feb 2020, 11:43 pm »

Update: I received the amp yesterday and neither the Canadian or US postal services caused any damage.

After letting the amp come up to room temperature I plugged it in for a short listen to ensure all is well. Sounds nice. I'm going to leave it on as it produces no heat and will listen more over the next few days. I hope to try out the balanced inputs once my dac (out on loan to another A/C member) returns.

After a few days with the amp, I plan on doing a side by side compare against my Nuforce HDP amp. I've been using the HDP for probably 4 years now as I stopped trying to better it.

adydula · « **Reply #45 on:** 20 Feb 2020, 11:54 pm »

Great!!

Good it got to you unharmed!

Will be very interesting on your comparisons to the Nuforce HDP amp.

Is the Nuforce amp just an amp or is it a dac/amp?

If thats the case can you only use the amp by itself or not?

Alex

timind · « **Reply #46 on:** 21 Feb 2020, 12:14 am »

The HDP is a DAC/preamp/Headphone amp. In my case though, I've really only used it as a headphone amp. I went looking for a review to give you a detailed description and found this. After skimming the article, I definitely agree with the assessment. And after reading the final paragraph, I guess I've been using the best part of the amp.
https://6moons.com/audioreviews/nuforce14/hdp.html

adydula · « **Reply #47 on:** 21 Feb 2020, 12:33 am »

Great and thanks for the information...

I kept seeing its a DAC/AMP combo and didnt want the dac to get in the way of any comparions....looks like its a Class A amp.

Thanks again!
Alex

adydula · « **Reply #48 on:** 29 Feb 2020, 09:04 pm »

THe HPA-1 arrived here today and I am listening to it right now...getting setup for tomorrow to do some critical listening and comparisons...

The amp apprived here in good condition!

I already have some first impessions and will share them with you soon!!

Alex

NOTE: Full disclosure this is NOT my amp. Its an amp that a member purchased and generously asked a few other members if they would like to try it out. It will head out here next week to another member. Many thanks to "that" member!!!

adydula · « **Reply #49 on:** 1 Mar 2020, 12:17 am »

First Impression sonically, is this is a wonderful amp....all around close to being a straight wire with gain...works well with all my headphones, more than enough power etc..

Lots more later...

Alex

adydula · « **Reply #50 on:** 1 Mar 2020, 03:58 pm »

Keith,

Its definitley not bright to me, its indeed very neutral in a brutal way...good stuff in good stuff out , Uncolored....put some trebly poor recorded stuff and your ears will bleed...its so very transparent and clean....

Some folks that are used to whats generally (in terms of amps) out there today as a "standard" might jump at calling this amp "bright" just because they havent used an amp of this quality.

Having the THX AAA amp for a few months tells me when an amp is designed with extremly low distortion etc...this is what neutral sounds like or "not" sounds like.

This morning I was listening to a variety of material most all very good quality stuff then a Kim Pensyl tune popped up and the treble in this "once" like tune made me cringe....on how "hot the treble" was in the recording.

With lesser amps its more tolerable.

I would call this a TOTL amp or a reference amp for sure.

Alex

Jon L · « **Reply #51 on:** 1 Mar 2020, 04:18 pm »

The advent of THX AAA amps have been a huge disruptor in the SS headphone amp market. The cheapest one, SMSL SP200 THX AAA-888 only costs $289.99, and one can literally buy three of them for HPA-1's price. Some reviews have even preferred the AAA-888 sound quality a bit over more expensive AAA-789.

0221202055 by drjlo2, on Flickr

If I were a SS headphone amp designer, I would face quite a challenge making an amp that sounds demonstrably "better/different" yet not come in at multiples of AAA amp prices, as can be gleaned from this Comparison review of AAA-888, AAA-789, and Benchmark HPA-4 ($3000).
https://www.youtube.com/watch?v=6Zuynm3o3vs&t=6s

Freo-1 · « **Reply #52 on:** 1 Mar 2020, 04:20 pm »

OK, thanks for the feedback. I do think that different amps that are tagged as neutral can have different sonic signatures, especially in the treble region. The Pure Bipolar amp is one of the very best headphone amps I've come across. It has a lot of reserve power, the circuitry is all balanced, and employs soft clipping when the limits are hit.

Since you have a variety of amps and headphones at your disposal, your views on the amp is very insightful.

To me, the headphone itself has more to do with hot treble sound than the amp.

adydula · « **Reply #53 on:** 1 Mar 2020, 04:31 pm »

With amps of this quality the material in is as important as the transducer used in listening...the amp just gets out of the way....

adydula · « **Reply #54 on:** 1 Mar 2020, 04:46 pm »

JonL.

Thanks for the video review link...I just watched this.

I am not saying the review is inaccurate, its his opinion etc....but the one thing thats missing and from many reviews that are very subjective..is actual
blind testing and having people not know what they are listening to and have them pick our the best gear etc..

But the fact still stands there is a wide price range on some good stuff out there for sure...

Again, some will not want a low cost amp made in China amp vs a billet aluminum cased amp....but something tells me more that the lower cost probalbly sells
more in the long run...

We should take this conversation to its own thread so folks can focus on the HPA-1.

https://www.audiocircle.com/index.php?topic=168509.new#new

Alex

Freo-1 · « **Reply #55 on:** 1 Mar 2020, 06:37 pm »

Tom,

I'll be using a Oppo Sonica DAC. Will that DAC be sufficient to evaluate?

tomchr · « **Reply #56 on:** 1 Mar 2020, 06:46 pm »

Oppo specs the Sonica (https://www.oppodigital.com/sonica-dac/) to "<-115 dB THD+N", which likely means that either a) they can't measure lower than that or b) the worst performance expected from the DAC is -115 dB but most perform better.

Either way, -115 dB THD+N is well below audible.

They also spec SNR to > 120 dB, so the noise floor of the DAC should be nice and low.

So, yes, I would say that the Oppo Sonica DAC would be a good candidate to test drive the HPA-1. Ideally, I would like to see a DAC with THD better than -130 dB and a noise floor below/around 1 uV (A-weighted), but that's a rather tall order. The Topping D90 should be able to get there.

Tom

Freo-1 · « **Reply #57 on:** 1 Mar 2020, 07:11 pm »

Thanks, Tom. I can also use the pre-amp out from a Devialet Expert 200 as well.

timind · « **Reply #58 on:** 1 Mar 2020, 11:29 pm »

That is a great write up Alex.

I had the amp prior to Alex and although I wanted to do a write up, I couldn't come up with anything useful to say. After reading Alex's review I know why. He summed up my impression perfectly with these words: "The HPA-1 has no real sound....other amps often have a sound signature, some like this and some do not,"

adydula · « **Reply #59 on:** 1 Mar 2020, 11:56 pm »

Here is a site that is very interesting that will help you determine how much distortion you can actually detect with your ears! And then can apply this in a meaningful way to a piece of gears distortion measurements and see if this will indeed matter or not in your listening experience:

http://www.klippel.de/listeningtest/

Here is a link to a discussion of the HPA-1 that speaks to this test and how it might
apply to whether or not these measurments have a correlation to what you hear or not.

https://forum.headphones.com/t/tom-christian-audio-tca-hpa-1-headphone-amplifier-official-thread/4982/40

You can read the entire discussion or scroll down to March 1 and read post 41. Very interesting read...

Alex