T+A DAC 200

[Shadorne]

53 minutes ago, OE333 said:

 

I just would like to add that T+A does not use the chip based filters from the DAC chips. All filtering is done by proprietary algorithms in a DSP.

Besides the FIR filters the DAC200 offers the choice of two BEZIER filters. These filters are no FIR filters, they use Bezier polynominal interpolation instead and these filters do not have any pre-echoes or any pre- or post ringing.

 

I am not concerned about the totally inaudible pre or post ringing. This is a simple mathematical reality that when you remove the higher frequencies you are left with what we call the Gibbs phenomenon on any transients close to nyquist. Since these are at inaudible frequencies (close to nyquist) it is a complete mystery why anyone should be concerned about this. 

 

It is principally the pre-echo from equiripple filters that concerns me. Any sinusoidal ripple in the pass band from filtering is going to produce two sync functions in the time domain either side of the zero. A sinusoid mathematically is two sync function either side of zero. This is a mathematical reality. So equiripple is mathematically a filter design problem. This sync or impulse echo is going to reflect off the input signal and produce an audible pre-echo (exact copy of the audio at a lower level). Almost all digital filters have a sinusoidal ripple in the passband - certain ripples are more audible than others. Most engineers dismiss these ripples once they are as small as 0.002 dB - thinking this is good enough is a mistake - even a passband as flat as 0.002 dB can produce audible pre-echoes and if the echo is within about 0.8 to 5 millisecond earlier than the main signal, our ears brain will detect it.

[OE333]

43 minutes ago, Shadorne said:

Almost all digital filters have a sinusoidal ripple in the passband.

 

To my knowledge upsampling of time-discrete functions by using interpolation methods like Bezier polynominals or cubic splines does not result in passband ripple - please correct me if I am wrong.

If this is correct then (as said in my post) the Bezier oversampling should not produce any pre-echoes.

 

[Shadorne]

33 minutes ago, OE333 said:

 

To my knowledge upsampling of time-discrete functions by using interpolation methods like Bezier polynominals or cubic splines does not result in passband ripple - please correct me if I am wrong.

If this is correct then (as said in my post) the Bezier oversampling should not produce any pre-echoes.

 

Do you refer to the final output digital filter or are you referring to the interpolation digital filters used in each stage to upsample?

[OE333]

1 hour ago, Shadorne said:

Do you refer to the final output digital filter or are you referring to the interpolation digital filters used in each stage to upsample?

 

The DAC200 has an upsampling stage where all incoming PCM data is upsampled to 16fs. The 16fs stream then goes directly to the sigma/delta converter, bypassing the internal upsampling filters of the DAC chips.

The analog output of the DAC chips is finally filtered by an analog reconstruction filter.

 

Given this signal path I was referring to the upsampling stage.  In case of the Bezier upsampling (OVS = BEZ1 or BEZ2) the upsampling is not done by stuffing Zeroes and then digitally filtering the stream, instead intermediate samples between the original samples of the incoming stream are computed by interpolation using Bezier polynoms.

[Shadorne]

50 minutes ago, OE333 said:

 

The DAC200 has an upsampling stage where all incoming PCM data is upsampled to 16fs. The 16fs stream then goes directly to the sigma/delta converter, bypassing the internal upsampling filters of the DAC chips.

The analog output of the DAC chips is finally filtered by an analog reconstruction filter.

 

Given this signal path I was referring to the upsampling stage.  In case of the Bezier upsampling (OVS = BEZ1 or BEZ2) the upsampling is not done by stuffing Zeroes and then digitally filtering the stream, instead intermediate samples between the original samples of the incoming stream are computed by interpolation using Bezier polynoms.

I don’t know what sort of band pass this might create - I guess this could be modelled if we knew the control points and the order. I would not expect T+A to share such proprietary algorithms. 
 

Inherently the Bézier curve is intended to fit control points as smoothly as possible, so I expect it would be smoother than traditional interpolation zero stuffing techniques.

 

I alluded in a post above that T+A seem to be aware of equiripples and pre-echo issues with traditional simple low latency interpolation in a typical DAC chip. I speculated this is T+A came up with Bézier functions.

[Miska]

In HQPlayer you can find such under names "polynomial-1" and "polynomial-2"... There are few other interpolators as well (listed under "filters" although these are not strictly speaking filters).

 

[stereousa]

@bogi, I think you misunderstood my first question. I did not mean to compare HQPlayer with Foobar. My point was, if Foobar2000 outputs DSD (PCM files converted to DSD), then will that sound better on the the DAC 200. I do not want to go the HQPlayer route. And this has to do nothing with the cost of it. I have a passively cooled server that I built on my own. It's based on Intel i7-12700 CPU in a Streacom FC10 Alpha case with 32GB RAM with 2 Samsung 970 EVO Plus NVMe. One for OS/Foobar200 and the other one for audio files. I heard that HQPlayer needs fans and GPUs. And I am completely with you on the personal experience - nothing to beat that - I understand.

@Shadorne, Thank You for the detailed response. It was helpful to understand the differences the DAC200 can make. BTW, you have a fantastic system!

@DonaldM, Thanks for the reference. Good to know.

[bogi]

My post doubled by editing.

[bogi]

3 hours ago, stereousa said:

if Foobar2000 outputs DSD (PCM files converted to DSD), then will that sound better on the the DAC 200

 

In my experience yes with all DACs I tried so far. But I cannot comment on DAC200 since DACs I tried used internal upsampling of DAC chips with PCM input.
 

3 hours ago, stereousa said:

I heard that HQPlayer needs fans and GPUs.

 

Not as a strict rule. You could find here people using HQPlayer on similar Intel CPUs like yours without add on GPU, for example with HQPlayer OS, which does not contain nVidia CUDA support. And some are using also passive cooled designs. At DSD256 you could have a chance and it could sound much better than foobar2000 at DSD512. In my opinion it is worth to try - trial costs nothing.

[Miska]

4 hours ago, stereousa said:

My point was, if Foobar2000 outputs DSD (PCM files converted to DSD), then will that sound better on the the DAC 200. I do not want to go the HQPlayer route.

 

It completely depends on the modulator implementation. The DSD DAC section in DAC 200 will just convert the data to analog. And all the complexity of creating best performance data for this section is at the source side.

 

4 hours ago, stereousa said:

I have a passively cooled server that I built on my own. It's based on Intel i7-12700 CPU in a Streacom FC10 Alpha case with 32GB RAM with 2 Samsung 970 EVO Plus NVMe. One for OS/Foobar200 and the other one for audio files. I heard that HQPlayer needs fans and GPUs. And I am completely with you on the personal experience - nothing to beat that - I understand.

 

Lot of people use less powerful passive cooled computers to run HQPlayer. I've used i5-7600T and 16 GB of RAM in the same case you are using to produce DSD256 to DAC 200. At the moment that same machine is still operating as a NAA for DAC 200, but the server doing the processing to DSD512 is now in a different room (and yes with fans and GPU). However, that machine is still running also HQPlayer to produce DSD256, but now to Marantz SA-12SE instead.

 

I think your machine would do DSD512 output to DAC 200 with HQPlayer just fine.

 

So don't trust rumours.

 

P.S. I would strongly recommend using Intona USB isolator between your server and DAC 200.

 

[Shadorne]

 

 

15 hours ago, Miska said:

In HQPlayer you can find such under names "polynomial-1" and "polynomial-2"... There are few other interpolators as well (listed under "filters" although these are not strictly speaking filters).

 

 

Agreed but they are obviously bandpass limited in the way the algorithms work or you could curve fit higher frequencies. So one can think of them as having an equivalent filter effect. An inherent artifact from the interpolation methodology is that it results in a bandpass limited signal. 

[Miska]

3 hours ago, Shadorne said:

An inherent artifact from the interpolation methodology is that it results in a bandpass limited signal. 

 

Low pass limited a very little bit yes. Not bandpass since DC goes through untouched.

 

[Asdfgh]

@OE333

 

An MP200 mk2 with the new streaming platform (Airplay 2, Spotify connect etc)with a dedicated NAA that can do 1024 DSD out to the DAC200 and control analog volume via software would be a fantastic product! Could you ask the team to chuck one together for me? 🤣

[kishoreburidi]

Agreed, what a killer product that would be… and will be a great saviour for my setup…

[droffen]

4 hours ago, Asdfgh said:

An MP200 mk2 with the new streaming platform

an upgrade of existing MP200 should be possible by end of this year already. 
 

[OE333]

@Asdfgh and @kishoreburidi

 

Well noted. We will check what is possible.

[CharlieR]

7 hours ago, OE333 said:

@Asdfgh and @kishoreburidi

 

Well noted. We will check what is possible.

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! (I see the specs state upnp server support but unsure if it works directly with Qobuz or if you need to go through another tool)

 

This also was why I was potentially interested in a i2s input to connect a Diretta target as I failed to get the Lucia to fucntion via USB.

 

thanks

 

[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

 

 

 

 

 

 

[OE333]

1 hour ago, davidv100 said:

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

 

 

It all depends on the target group.

 

Members of this forum have a lot of experience and knowledge and want to be at very foremost edge of technology. For this kind of audiophile users a good quality but standard streamer might not be the source of their dreams.

 

But from my experience 90% of the customers of audio equipment are no such extreme audiophiles. These customers do not really care about extreme sampling rates, about the most sophisticated upsampling schemes, room-EQ etc. They just want an excellent sounding but uncomplicated system with easy set-up and easy operation. For them a reliable streamer, integrating access to almost all music content in one box, with consistent operation, perfectly tuned and matched to their DAC +PWR AMP is just what they want. For these customers the MP200 is the ideal solution.

 

[bogi]

2 hours ago, davidv100 said:

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).

 

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?

 

2 hours ago, davidv100 said:

How can any High End Audio Brand (with tenth or hundredth employee) compete against behemoths like Apple, Samsung

 

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.

[Miska]

4 hours ago, CharlieR said:

for those who don't know Diretta it is similar to NAA but with supposedly improved sound quality

 

If you ask me, trying to be similar, but with spoiled sound quality. 😂

From my perspective, it is just doing things wrong. Maybe someone could like it with some other software. But with HQPlayer, nothing beats NAA which is integrated straight into HQPlayer engine and is optimized for best possible sound quality. Plus of course doesn't have any licensing fees for device manufacturers.

 

[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.

[Miska]

43 minutes ago, davidv100 said:

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.

 

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.

 

[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 👍 

[Miska]

On 9/15/2023 at 12:15 PM, davidv100 said:

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 👍 

 

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.