Topping DM7 8-Channel DAC Review

[sarumbear]

All a DAC does is convert numbers to signals.

But S/W either decodes 5.1, 7.n.n etc, or does bandpass filtering for a crossover, so something on that order.

That is not an answer to my question, nor related to your argument that you can calculate SINAD of an audio processing software.

 

[dartinbout]

I have an interesting question. I have alerts to notify me of any new mention of the Okto DAC 8 Pro. As far as I can tell, there is 0 chatter about this lovely product, outside of ASR, where it is fairly treated as a gift from Zeus, Odin or whatever deity you pray to. Do you think we inspired Mr. Yang and Topping to create the DM7? Also, there is very little interest in the other audio channels, I follow, in surround sound. Did ASR begat this?

 

[Trell]

That is not an answer to my question, nor related to your argument that you can calculate SINAD of an audio processing software.

I’m not the poster you asked but of course you can “measure” the output of software as this is what you’ll send to the DAC.

I’ve written so in earlier replies to you.

 

[mdsimon2]

I have an interesting question. I have alerts to notify me of any new mention of the Okto DAC 8 Pro. As far as I can tell, there is 0 chatter about this lovely product, outside of ASR, where it is fairly treated as a gift from Zeus, Odin or whatever deity you pray to. Do you think we inspired Mr. Yang and Topping to create the DM7? Also, there is very little interest in the other audio channels, I follow, in surround sound. Did ASR begat this?

Inspired? I think it was more like specifically asked for it. There were several threads directly asking for Topping / SMSL to make this. Interestingly enough those threads followed a very similar pattern as this thread, some folks are happy with a simple 8 channel USB DAC and others want tons of I/O options.

This post has a collection of a bunch of recent threads discussing hypothetical multichannel DACs -> https://www.audiosciencereview.com/...channel-dac-review.35661/page-25#post-1248907.

Michael

 

[Kal Rubinson]

Inspired? I think it was more like specifically asked for it. There were several threads directly asking for Topping / SMSL to make this. Interestingly enough those threads followed a very similar pattern as this thread, some folks are happy with a simple 8 channel USB DAC and others want tons of I/O options.

There has been an expressed need for such an affordable MCH DAC for quite a while but, apparently, Topping/SMSL has only now seen good reason to market one. I had an extended email discussion with Topping/SMSL about an 8channel DAC and/or the possibility of clock-synching multiple stereo DACs about 3-4 years ago.

 

[sarumbear]

I’m not the poster you asked but of course you can “measure” the output of software as this is what you’ll send to the DAC.

I’ve written so in earlier replies to you.

My question was how do you calculate SINAD of a software routine that does audio processing.

 

[Trell]

My question was how do you calculate SINAD of a software routine that does audio processing.

How to technically do it depends on the software used for analysis, so those of the members that does that can chime in. There is no magic here as you know the input as well as the output.

 

[sarumbear]

How to technically do it depends on the software used for analysis, so those of the members that does that can chime in. There is no magic here as you know the input as well as the output.

In other words you don’t know but you assume it must be done. Ignorance is bliss, they say…

 

[Trell]

In other words you don’t know but you assume it must be done. Ignorance is bliss, they say…

You’ve been going on and on with this topic here and early on it was clear that you know nothing about software development, and a little rude as well.

Instead sidetracking this thread further, why don’t you create your own thread about analysis of output from software that does audio processing?

There are many members here on ASR that could give very good info on this subject.

 

[nagster]

You used the wrong adapter(s).

Thank you.
I use reasonable means. The origin and background of the adapter was irrelevant to the result.

This DAC uses TRS sockets. Telephone switchboards are different size and shape.

Yes.

 

[KSTR]

My question was how do you calculate SINAD of a software routine that does audio processing.

There is no difference for the analyzer software wrt SINAD and other measurements and calculations. It processes/analyzes a digital audio stream, no matter where it comes from.

 

[sarumbear]

There is no difference for the analyzer software wrt SINAD and other measurements and calculations. It processes/analyzes a digital audio stream, no matter where it comes from.

How do you define distortion in a digital signal?

 

[KSTR]

How do you define distortion in a digital signal?

???
In the normal way: any distortion and noise in the output that we know should not be there, other than your regular dither (if operating fixed-point) of course.

 

[sarumbear]

???
In the normal way: any distortion and noise in the output that we know should not be there, other than your regular dither (if operating fixed-point) of course.

But in a mathematical calculation like a filter what can be added other than dither?

PS. I’m not trolling you. I really want to learn.

 

[KSTR]

But in a mathematical calculation like a filter what can be added other than dither?

Depends on what you want to do.

And correct, a static EQ & gain process should not alter the output signal besides the expected gain/EQ characteristics and some amount of dither.

With compressors/limiters it's not that easy as they have transient distortion by definition and there is always a ripple on the gain control value the moment there is any compression/limiting even when the signal is a steady-state sine or sum of sines (multitone). There will be residual distortion by "principle of design" even if the implementation is clean (with look-ahead and oversampling).

For processing that introduces nonlinear distortion (hardware modelling, for example) we can at least check if there is no massive amount of aliasing.

 

[voodooless]

But in a mathematical calculation like a filter what can be added other than dither?

Try using linear interpolation to “upsample” some audio and see what it leaves behind..

 

[msmucr]

But in a mathematical calculation like a filter what can be added other than dither?

PS. I’m not trolling you. I really want to learn.

Hopefully I'm getting correctly your post. There can be pretty significant artifacts even from "simple" filter processing.

For example even nowadays it's not so rare to find out vendors, who still calculate recursive filters with single precision. Be it software or hardware like AVRs or digital crossovers.
As an example check my old post there..

Emotiva XMC-2 Review (AV Processor)

The main difference is that I was only driving two channels and they are driving all 8. Someone commented that the bug in bass management may be the problem here and this would sort of point to that direction. Amir, thanks for the review. Just what came to my mind about tilted noise...

www.audiosciencereview.com

(and also plots in the OP)

So IMHO it makes sense to test and examine how digital processing is done in each particular product and don't just assume, it's O.K.

Michal

 

[edechamps]

There can be pretty significant artifacts even from "simple" filter processing.
For example even nowadays it's not so rare to find out vendors, who still calculate recursive filters with single precision. Be it software or hardware like AVRs or digital crossovers.

In a previous life I found myself implementing RBJ EQ filters for a pet project. I made the mistake of coding the biquad in 32-bit float (single precision) instead of 64-bit float. The numerical inaccuracy that resulted produced somewhat subtle, but audible issues. Most notably high-order distortion in bass tones, easily visible in measurements. Changing the code to use double precision solved the problem.

In general distortion introduced by digital filters is negligible, under the important condition that they are implemented correctly.

 

[sarumbear]

Open thank you to the members who beared with me and explained how distortion can happen on digital processing. I learned something today.

 

[gvl]

Some posters here wants a Topping AVP for $600. That won’t happen anytime some.

Definitely not before they can make a $300 amp reliable.