T+A DAC 200

[davidv100]

Hello,

I own a T+A DAC200, bought primarily for a speaker setup.
Now, I would also like to enjoy the headphone output.

I am thinking about buying a Sennheiser HD800s.

But I have no idea if this is a good match based on power, impedance and stuff.

Would somebody be so nice to help me out ? Would be awesome.

 

For the T+A Dac200, I read : "4.4 mm Pentaconn, I read : 6 Ohms output Impedance, Class A operations up to 200mA"
For the HD800s, I read : Sound Pressure Level (SPL) : 102 dB (1V), Impedance 300 Ohms...

 

Remember T+A Dac200 headphone output (4.4 mm) is balanced (If relevant here)

Ehm... so ? Is this compatible ? Do we have a match in heaven ? Or not at all ?

Thanks a lot.

[davidv100]

13 hours ago, OE333 said:

 

Of course, as @droffen suggested, the Solitaire P / P-SE are a perfect match with the DAC200.

But the Sennheiser HD800 is one of the headphones which is used regularly by the T+A development dept. for listening tests and it also works extremely well with DAC200.

Thank you very much !

[davidv100]

On 9/7/2023 at 6:01 PM, OE333 said:

 

Of course, as @droffen suggested, the Solitaire P / P-SE are a perfect match with the DAC200.

But the Sennheiser HD800 is one of the headphones which is used regularly by the T+A development dept. for listening tests and it also works extremely well with DAC200.

Thank you very much OE333.
I am more a speaker guy (I have the DAC200 and not the HA200), and therefore, not willing to go the whole way to the T+A headphones (too expensive for my humble use - may reconsider latter).

Now, OE333, If I may, I have another question. I changed my minded and now considering the Arya Organic over the Senn HD800S. Be reassured I am not going to ask your advise about any possible speaker.

 

My question is more generic. I looked about a ton a headphone/amp pairing YT videos, especially regarding the "Impedance" question, and came out more confused than ever before. Some say high impedance headphones (say 300 Ohms) demand more current than lower impedance headphones (says 16 Ohms), and some say the exact opposite.

 

So, since there is such a huge impedance difference between the HD800S (300 Ohms) and the Arya Organic (16 Ohms), and as you said the HD800S would be a good match with DAC 200, would that mean the Arya Organic (16 Ohms, 92Db Sensitivity) would be a poor match ? Or not at all ?
 

("Not at all, David, the Arya Organic would actually be an excellent match for your DAC200, and I will explain you why" being the preferred answer :-)  ).

As a reminder : DAC200 outputs says "8 Ohms, 200mA Class A current".

Thank you so much for sharing your knowledge.

 

David, Belgium

 

[davidv100]

53 minutes ago, OE333 said:

 

A low impedance HP will require higher current than a high impedance HP for a given sound pressure level - provided both headphones have the same sensitivity in dB/mW.

On the other hand the high impedance HP will require a higher voltage.

 

 

 

Even though I personally have no experience with the Arya headphone, I don't see any problems for the DAC200 driving it.

 

The DAC200 can deliver about 0.64 W into the 16 Ohms of the Arya and about 0.35 W into the 300 Ohms of the HD800S.

In both cases more than ever will be needed...

 

Thank you sooooo much OE333.
Finally somebody with true knowledge, providing understandable science-based answers, and your "watts" answer is so helpful.
Why doesn't everybody refer to U=RI, and P=UI=RI^2, just like you do.

Now I get the global compatibly idea thanks to you translation to Watts.
 
(Why don't all components / headphones makers provide this Power/Watts information).

You reeeeealllly helped me so much !
You made my day.

 

PS:
Then obviously I understand that Z (Impedance) is frequency dependent and makes the whole thing a bit more complicated across the spectrum. I understand high headphone impedance leads to more linear response from this excellent YT video : 

But I guess that part will be ok.
Thanks again, OE333.

[davidv100]

29 minutes ago, bogi said:

That's relevant for electrodynamic headphones like HD800. High impedance makes easier to pair them with headamps which don't have extra low output impedance.

 

Impedance of planars is known to be constant across frequency spectrum, so 16 Ohm impedance should not cause an issue with any headamp. Because of that constant nature, planars impedance is often not published as graph but only mentioned as a value. Here you can see for example impedance graph of my HE-500:

 

What low impedance and not quite low sensitivity headphones need is enough current.

Thank you very much, Bogi.
I was not aware of this main impedance distinction between electrodynamics VS planars, and its implications.

Your info indeed does solve the two last questions I was still trying to hide in my mind (ie : "what about this x8 rule ?", and "what about the whole frequency spectrum ?").

But I understand now this mainly applies to electrodynamics headphones, not planars.

You cannot imagine how much I have learned from both of you, Bogi and OE333 today.

So much YT videos out there about this topic, but always with too much blah blah blah, and not enough simple, science-based info, and precision about the use case (ie : electrodynamics VS planars).

I am a more clever person now, and feel way less in the dark choosing headphones.

Thanks.
Have a nice Sunday and a beautiful week.

David

[davidv100]

Dear OE333,

Have you ever thought about building a DSP room treatment module for the T+A DAC 200 ?
- Would it be technically possible ?

- Would it make sense ?
 

More generically, is a DAC the right place to fit-in DSP room treatment ?
My feeling is yes - but I may be totally wrong.

Thank you very much for your answers - will be interesting. 

[davidv100]

9 minutes ago, OE333 said:

 

T+A has a very long tradition in digital room equalization: back in 1995 T+A launched the Solitaire A2D active loudspeakers containing a digital room-EQ  system with 11 DSPs per speaker (quite expensive at that time) and the MEP room measurement system.

 

With this background we of course thought (and think) about digital EQ for the current T+A devices but in my opinion the DAC would be the wrong place for it. Room EQ requires a lot of computing power and I don't like the idea of integrating this much digital computing hardware into a DAC because it would inevitably bring problems with electromagnetic interference and adverse effects to the analog parts of the DAC.

Furthermore there is enormous progress in computing power every year so any room-EQ digital hardware would be outdated in short time.

 

This is why I believe that room-EQ today should be done in a powerful audio-PC. If you use HQ Player or roon, then these systems have already everything on board you need for room-EQ.

The e.m. interference is no problem in this case because all digital processing takes place in a separate box and last but not least a PC can easily and at reasonable cost be upgraded or exchanged when higher performance hardware appears on the market.

 

So my two cents in one sentence: Do the processing in a dedicated audio PC and keep the DAC electromagnetically as clean as possible.

OE333,

Thank you very much.

very clear answer again.

I will dig a bit deeper into computer based solutions indeed.

 

Have a nice day,

 

David

[davidv100]

3 minutes ago, CharlieR said:

Well if an updated version could potentially be on the card I would like to chime in as well, I had bought a Diretta Lucia (https://www.diretta.link/) to connect to my DAC-200 (for those who don't know Diretta it is similar to NAA but with supposedly improved sound quality) but there was an issue with the DAC-200 USB connexion and the sound was horrific (screetches, sratches, pops) while the same setup was working just fine with other USB implementations (I tested Chord Dave and Weiss 501) I never managed to figure out the source of the problem and I am now back to my AES input (some people blamed the "exotic" USB chip in the DAC-200 or a clocking issue)

 

If T&A was willing to investigate adding Diretta target functionalities to the MP200 mk2 it would be amazing (I guess we no longer need that MQA license now!) and also to have UPNP/DLNA support to play Qobuz (until they finally release that Qobuz Connect functionality) it would help me reduce the number of cables and devices I have!

 

thanks

 

Tbh, although I fully respect my DAC200 for its exceptional sound and built quality, my PERSONAL view (FWIW) about High End Streamers is a bit different, and I would like to share it to check how wrong I am.

I really do not see how a streamer, as high-end as it can be, can beat a recent iPad, or whatever high end Android Tablet...

Let me explain...
DAC200 is supposed to have a very good USB galvanic isolation, and a very good clock. If my understanding is correct, the downstream clock (DAC200) is master for the upstream source(the iPad, the Android tablet).

Then, with a tablet (iPad, Android), if it is well build, you are isolated from any power pollution (since its internal battery acts a buffer) - It is even better than any high-end power solutions "rebuilding the current".
So,
- you are out of any jitter issue (DAC200 clock is master of timing);

- you are out of any power pollution issue, twofold (Tablet running on battery as a buffer, galvanic isolation provided by DAC200).

Then, what is remaining ?

For a streamer, you absolutely want upgradability, as it is a fast moving world.
For example, my music source is Apple Music Hi-Res (24/192), and I hope some time Apple will provide "Apple Music Connect", just like "Spotify Connect" or whatever. The Tablet could also be home to DSP room correction or whatever...

How can any High End Audio Brand (with tenth or hundredth employee) compete against behemoths like Apple, Samsung, with tenths of thousands of employees in terms op upgradability and time to market ? Plus, these behemoths are shipping units by millions... The price of there unit might appear as being rather low... Giving a false idea of their real value. There price is only possible thanks to the volume, otherwise they would cost x times the price.
How to compete when you are selling hundreds, thousands units at best... How to compete with their native connectivity with your phone as a remote ? It is just impossible.

According to me (I am wrong ?), the Audiophile Streamer battle is a lost battle. Except for elder people afraid of "anything digital", but obviously this is a shrinking market...

Dear OE333, how wrong am I ? Totally wrong ? Average wrong ? Actually not that wrong ? 

Thank you,

 

David

 

 

 

 

 

 

[davidv100]

9 hours ago, bogi said:

 

AFAIK some parts of the above quote are simplified and others are incorrect.

 

I read about galvanic isolation between digital and analog part of DAC200. I did not read anything about galvanic isolation of DAC200 USB interface at its input side. What I observed is Miska's recommendation (few posts above) to use Intona USB isolator with DAC200. Please correct me if I am wrong.

Then, you don't seem to know much about audio source noise impact to DACs. It is not limited only to ground loops, which you cannot get with battery powered digital audio source. Phones, tablets and portable audio players, like every computer or digital device, are source of high frequency noise, which does not have character of DC causing ground loops. With portable, battery powered devices you are not free of noise impacts to USB connected downstream devices.

 

Now about convenience of use. You are thinking about iPad or Android device connected by USB cable to DAC200. Is that convenient for mobile device operation in loudspeaker setup? Will you lead 5 meter long USB cable from DAC200 to your sofa? Or do you want to move from your sofa to DAC200 every time you want to operate your battery powered device?

 

How long time you can stream from your iPad or Android device from built-in battery? Will you care to charge it every night? When it gets out of power, will you stop listening, or will you connect a charger? Isn't then your thought advantage of battery power lost?

 

 

Simply said, MP200 and similar devices are targeted to customers, which want the best possible sound and at the same time the most convenient way to use different streaming services and ways to connect other audio devices. What's OK for you my be not OK for others. Devices like MP200 are targeted to customers who understand and are interested in the added value.

Thank you OE333 and Bogi,

I understand my perspective is not that popular, and as you say, it is everybody’s own choice.

 

Thank you also for correcting some of my points, like galvanic isolation.

 

Just a clarification for Bogi : Of course I was referring to a dedicated IPad that is staying powered, and also staying connected to the DAC200. My “Streamer IPad” never moves.

 

But anyway, thanks again to both of you. Have a splendid week end.

[davidv100]

2 hours ago, Miska said:

 

I have iPad similar way for Apple Music and such (only way to get bit-perfect output from Apple Music). The only difference is that I have HQPlayer computer as upsampler between iPad and DAC200. Things like Qobuz and local library are played natively with HQPlayer and there the audio doesn't go through the iPad.

 

And thus, the DAC200 stays in DSD512 mode always.

 

Clever indeed.

If only Apple Music would allow to capture it’s stream on the same device, you could actually remove the iPad and only use the MacBook. I would want to do that too (or the other way around if HQP could run on a (powerful) IPad.

But for now, I understand you need both. I hadn’t thought about chaining iPad + MacBook. Good idea 👍 

[davidv100]

6 hours ago, Miska said:

 

It should work with loopback driver. But Apple Music is never bit-perfect on macOS because it always plays through the CoreAudio's shared mode rate converter/mixer. So the output format is fixed to what ever has been set in Audio MIDI Setup. But on iOS it is bit-perfect and can switch output format based on the source format.

 

Yes - I hope this whole Apple Music thing will be revamped someday.

 

Now, as I am the one who stated polluting this DAC200 thread with more and more diving into Apple Music specific things, I also suggest to close the chapter here, so that we come back to DAC200.

 

Thank you all for your input.

I have learned a whole bunch of interesting things.

[davidv100]

Dear OE333,

I have a suggestion for a firmware evolution indeed.

Long version (to relate)

I just received my Hifiman HE1000 Stealth planar headphones and they work fantastic plugged into the DAC200.
Then using my new headphones, I had confirmation that I had an imaging issue in my speaker set-up.
Then I tried to do a first easy room-correction with changing the balance on my Speaker Plinius PreAmp. It worked.
Then I realised for the first time that my Speaker Plinius Preamp had an issue as there is a hum I never heard before. So I had to remove it immediately from the chain for service. It could obiously not remain there one more minute.
Then I thought I have an easy temporary fix : I will use the preamp function of my DAC200 to directly feed my Plinius Amp.

But I still have to adjust the balance (-5 Db left) for room correction which I did on the DAC200.
Everything works and it is all fine.
Then I wanted to continue enjoying my new HE1000 headphones connected to the DAC200, so that I could forget about my broken pre-amp and not think about the crazy amount this will cost.
Then I realised that the balance adjustment on the DAC200 for the line out the amp (-5 Db left) also applied to the headphones.
Which is not a good idea.

Short Version

 

I think the balance setting for the "Headphone Out" should be independent from the balance setting for the "Line Out". I mean, it is not just me, I guess :
- Adjusting the Line-Out balance (Speaker Balance) is a first fix for room-correction (asymmetric room, glass panels on the side).
- Adjusting the Headphone balance is... something no-one should do, unless the person is hearing impaired.

Is this fixable with a firmware ? If not, I can obviously change manually every time... but it is a bit sad for such a nice device. An "in-between" fix (that would work for 99% of people I guess) would be to propose an option to disable the balance setting for the headphone output ("Headphone Balance : Bypass : Y/N"). I actually thought this is how DAC200 would work natively, as it seems natural (Balance only applicable for Line Out).

Does my suggestion make sense (I hope so) ?
Thank you very much !
Have a great day.

 

David, Belgium



 

[davidv100]

Dear OE333,

Following my question above, I have a rather candid question for you.

As I explained earlier, My speaker chain used to be DAC200 -> Plinius M8 PreAmp -> Plinius SA201 Amp -> Martin Logan Summit Electrostats.
Now, since my PreAmp needs servicing, my chain is DAC200 -> Plinius SA201 Amp -> Martin Logan Summit Electrostats.

At first, I was thinking about servicing/replacing the Plinius M8 PreAmp.
But I am now questioning this as DAC200 seems to do the job pretty well (But I cannot A/B test).

So, my candid question :
Would you say the preamp of DAC200 is "state of the art", meaning I need no other preamp actually.
Or would you say DAC200 is mainly a DAC, with a rather good preamp coming as a perk, but an external preamp would still be better.

Also, is the volume control of DAC200 done digitally (before/in the DAC Stage), or is it done in the analog stage (not digital) ?
And which is better ?

Thank you very much for your highly valuable advice,

David  

[davidv100]

Thank you Apollo / Dirk.

I didn't know about this Violectric HPA 550 PRO preamp. But I googled a bit an it seems to be a very decent pre-amp.
So your feed-back is very interesting indeed. Thanks a lot for this already from a Belgian fellow.

Still wondering what OE333 will have to say about it from his own POV, but in the meantime, let's wish him very nice holidays.

[davidv100]

11 minutes ago, OE333 said:

 

No question, the pre-amp inside the DAC 200 is a state of the art pre-amp. It is based on the discrete (no OP-Amp) circuit technology from T+A's highly rated HV series and it is really a no-compromise top design.

 

The volume control in DAC200 is purely analog. It is a so-called logarithmic switched resistor ladder using hermetically sealed gold contact relays and audiophile non-magnetic high precision resistors. This kind of volume control is quite expensive but it is hard to beat and it is superior to digital volume control because it does not loose resolution when turned down to normal listening level. In contrast, the only advantage of digital volume control imho is its low cost - in a DAC it comes for free at absolutely zero cost.

 

 

Thank you very much OE333,

And thank you very much also to Apollo and Hydrology,

The return of experience of Apollo and Hydrology, plus the confirmation by OE333 will lead me to do just as they did.
I will be skipping the external preamp and use DAC200 in full : DAC + Preamp.
Less connectors, less cables, less loss... my only remaining issue will be to cope with the funeral of my previous preamp, and dig a decent grave in my backyard, in loving memories and stranded money.

Now of course, this also confirms that my previous question regarding the balance (headphone <> line out) makes sense.
If there were a way to disable the balance setting for the headphone, it would be perfect.
If not, I will obviously survive as I am super happy with my DAC200 anyway.
Plus this online support by OE333 is a very valuable add-on for the T+A community.

Thank you very much to the three of you,

 

David
 

[davidv100]

18 hours ago, OE333 said:

This weekend I found the time to work on the DAC200 firmware with extended features. I integrated the following additional functions:

1. 2nd USB input
2. separate VOLUME & BALANCE settings for Pre-Amp mode and headphone mode
3. settings for OVS, WIDE and INVERT stored separately for each input
4. screen saver mode (automatic dimming of the display)

The other suggested features (disable remote control for Volume only &  HT Pass Through) I will probably include in the next eXtended firmware version.

 

I will do a little testing now with the new version and I will release it in short time.

If somebody is interested in this extended firmware, please send me a PM, I will then send you a link to download it.

 

 

Hello OE333,
So you did succeed in separating VOL&BAL settings for PREAMP&HP.
This is great (not only for me, as I do think this is a real improvement overall).
Congratulations and thank you very much !!

David, Belgium

[davidv100]

1 hour ago, OE333 said:

Dear @GoldenOne

thank you very much for sharing your measurements and your profound comments on the DAC200.

 

I would like to give some additional information on the following passages from your review:

 

"And also worth noting, the DAC section is galvanically isolated from the digital section, and we can see a SI8660BA isolator chip on the board just to the right of the DAC section. Interestingly, it seems that the clock signals themselves also run through this chip, rather than having the clock source on the DAC side of the isolation barrier. I unfortunately can’t say for certain given as I cannot look at the underside of the board, but there doesn’t seem to be a clock source close to the DACs nor any sort of controller that would facilitate a PLL, so it seems that the PLL and clock itself are on the other side of the isolation barrier."

 

It is correct, that the DAC clock is generated on the "digital" side of the isolation barrier. This is done to keep the noise generated by the digital clocking section out of the DAC and analog section of the DAC200.

To avoid possible jitter, that might be caused by distance and by the SI8660 isolatior chip, the clocking signals are separately transferred to the DAC section via impedance controlled PCB traces and all relevant signals are re-synchronized directly at the DACs. To keep the DAC clock jitter free, a special high frequency pulse transformer (instead of integrated isolator chips) is used for its galvanic isolation.

We found that this technique keeps digital noise effectively out of the analog section and it preserves extremely low DAC clock jitter.

 

 

"... these features are all controlled by an ARM microcontroller by STM."

 

It may look like, but the DAC200 is not controlled by the ARM processor, it is controlled by a MSP3430 micro controller which is located on the front panel PCB.

The ARM controller on the signal board serves as USB input and DSP for the audio signals. This USB receiver is a proprietary T+A development, combining (UAC 3 compliant) USB reception, digital signal processing and generation of the input and control signals for the 1-bit DSD DAC on a single chip. This avoids extended digital circuitry and keeps electro-magnetic noise at a minimum.

 

Intersample overs

Yes, the DAC200 may show some clipping when intersample overs occur. This clipping could easily be avoided by adding some headroom in the oversampling filters. But of course, adding headroom will (as you correctly state in your comments) decrease the signal/noise ratio. 

According to my understanding intersample overshoot can only occur with audio signals close to the upper end of the pass-band and with amplitudes close to 0dBFS. Such signals are very rare in real life and I am really not sure, if avoiding some (minor) clipping at 20kHz/0dBFS is worth sacrificing S/N over the whole frequency band.

So, if it is the general opinion, that intersample overs constitute a severe problem, I will be happy to discuss this matter with my former colleagues at T+A to see if it makes sense to introduce a few dBs of additional headroom in the oversampling filters.

 

Thank you very much OE333 for this very comprehensive technical answer.

 

I am curious to know your take about GS’s statement that DSD is so much better than PCM on DAC200.

 

My point is that I have always wanted to avoid adding a computer and HQP in my audio chain (as a personal choice for simplicity). Should I reconsider this if DSD is so much better (I am purely questioning PCM to DSD conversion, not about the other features of HQP like oversampling).

 

Thank you very much.

[davidv100]

4 hours ago, davidv100 said:

Thank you very much OE333 for this very comprehensive technical answer.

 

I am curious to know your take about GS’s statement that DSD is so much better than PCM on DAC200.

 

My point is that I have always wanted to avoid adding a computer and HQP in my audio chain (as a personal choice for simplicity). Should I reconsider this if DSD is so much better (I am purely questioning PCM to DSD conversion, not about the other features of HQP like oversampling).

 

Thank you very much.

To @OE333 
I forgot to mention I already proudly own a DAC200 and I am very happy with it, using PCM.
So, my question is more precisely : should I be even happier with converting PCM to DSD upfront (using HQP) ?

PS: For the sake of being complete, I am adding that GS has also posted his analysis of DAC200 on Head-Fi, with some additional context. For example GS is praising the excellent Pre-Amp stage of DAC200, confirming what we already have been discussing above. So, this is also nice... 

[davidv100]

41 minutes ago, OE333 said:

 

I would recommend to try it.

Install HQP, use the free of charge test mode, convert to DSD256 or higher and listen.

There will be a difference.

If it is worth the additional complexity or if you want to stay with your DAC in PCM mode (which also gives a very high sound quality and is absolutely not bad !) only you can decide...

 

If @GoldenOne has not yet done all the rushes for his upcoming video, I hope he will be mentioning how you replied, and how you listened to the community for further improvements and building parallel software upgrades. According to me, your commitment is unseen in the audio community. Plus DAC200 is an incredible all-in-one devise including both a pre-amp and a head-phone amp. I hope GO/GS will mention this.
 

Kudos to both of you, @OE333 & @GoldenOne

[davidv100]

Hello,
I am a bit puzzled about what exactly is Dolby Atmos and Apple Spatial Audio.
How does this translate in bits and bit rate : Is this 24/192 or is there no link ?
Are these formats supported by DAC200 ?

I understand at least one thing : when listening to Apple Spatial Audio thru my DAC200 and Hifiman HE1000 V3 headphone, the sound will obviously not change direction when I turn my head. But even more obviously, I do not care at all about that.

So, my question is only about the sound quality :
1) what are these formats exactly ?
2) are they supported by DAC200 ?

Thank you very much

David  

[davidv100]

10 hours ago, russellbobby said:

Just hook this up. Sounds pretty good cold.  I bought it used and the lights  on the meters are not operating. I have been thru the menu system but having no luck. 
Any ideas?

thanks
 

Very dumb (but possibly useful, tho) suggestion : Have you been checking in the dark ?