Which Subwoofers supports digital in?

[gabrielb]

Many upscale SUBs support crossovers, adding delays and a few other DSP tricks.
I understand that it is possible to perform some of this in the analog domain, but won't it be much easier for them to simply add a Digital interface (e.g. SPDIF), perform lossless DSP in the digital domain and then pass the stream through a DAC chip?

It is right to assume that such an implementation will be superior to running the DSP in the analog domain (or even run an ADC conversion before doing DSP)?

I tried looking for good SUBs with digital IN and the only one I saw was genelec.
Did I miss something?
Why don't they all support digital-in instead of performing ADC?

 

[SigbergAudio]

A few reasons I can think of:

A) There are not a lot of sources out there that could provide the subwoofer with digital input
B) Derived from A, very few customers require this functionality, so there is little point to implementing it
C) The AD/DA conversion within a subwoofer DSP is for all practical purposes transparent, so you don't achieve any tangible benefit.

 

[Vacceo]

A few reasons I can think of:

A) There are not a lot of sources out there that could provide the subwoofer with digital input
B) Derived from A, very few customers require this functionality, so there is little point to implementing it
C) The AD/DA conversion within a subwoofer DSP is for all practical purposes transparent, so you don't achieve any tangible benefit.

Since you have designed subwoofers, you´re perhaps the person to ask this. Distortion in the low frequencies, even more so in the very low frequencies, is quite hard to notice so is it worth it to trade clarity in the amp for power? Also, considering modern class D amps, I guess that is a false dichotomy.

 

[unpluggged]

running the DSP in the analog domain

How can one run digital signal processing in the analog domain?

lossless DSP

What is this?

I tried looking for good SUBs with digital IN and the only one I saw was genelec.
Did I miss something?

Neumann, HEDD... I'm sure there are others. But is it that important?

 

[SigbergAudio]

Since you have designed subwoofers, you´re perhaps the person to ask this. Distortion in the low frequencies, even more so in the very low frequencies, is quite hard to notice so is it worth it to trade clarity in the amp for power? Also, considering modern class D amps, I guess that is a false dichotomy.

Before answering, I am not sure I understand what you are asking. What do you mean by "is it worth it to trade clarity in the amp for power" ? If it's worth it to accept higher distortion to get more power? Or?

 

[Vacceo]

Before answering, I am not sure I understand what you are asking. What do you mean by "is it worth it to trade clarity in the amp for power" ? If it's worth it to accept higher distortion to get more power? Or?

Higher distortion amplification for more watts.

 

[SigbergAudio]

Higher distortion amplification for more watts.

If you have to drive the amplifier into distortion, the amplifier is too small, I'm not sure I see the point of creating such a design. To save cost?

So my answer to your question would be no. I do not think (even for subwoofers) that you should accept amplifier distortion.

 

[escape2]

How can one run digital signal processing in the analog domain?

My guess is OP took a bit of a shortcut in his train thought. He probably meant that a typical sub has to do ADC on the incoming signal before it can apply its DSP magic.

 

[gabrielb]

How can one run digital signal processing in the analog domain?


What is this?

Neumann, HEDD... I'm sure there are others. But is it that important?

Sorry, I meant Signal Processing like crossover in the analog domain.
The way I see it crossover in the digital domain is lossless and you perform a clean cut in the frequencies.

Without a digital IN you either do an ADC->DAC which by definition is lossy, or you perform analog crossover/delay which I *assume* add some (hopefully minimal) distortion

 

[gabrielb]

A few reasons I can think of:

A) There are not a lot of sources out there that could provide the subwoofer with digital input
B) Derived from A, very few customers require this functionality, so there is little point to implementing it
C) The AD/DA conversion within a subwoofer DSP is for all practical purposes transparent, so you don't achieve any tangible benefit.

Thanks!
I agree that the demand doesn't really exist so there is not a lot of supply to meet it.

Regarding that last point, why is the AD/DA conversion within a subwoofer DSP is for all practical purposes transparent?
Is it because distortion in the low frequencies is hard to notice like Vacceo said?
If this is the case, a basic DAC installed between the digital source and the SUB could eliminate the need for a digital in for a low cost?

​

 

[unpluggged]

The way I see it crossover in the digital domain is lossless

Again, what is a "lossless crossover"?

Is it because distortion in the low frequencies is hard to notice like @Vacceo said?

No, it's because modern electronic AD and DA converters are audibly transparent.

If this is the case, a basic DAC installed between the digital source and the SUB could eliminate the need for a digital in for a low cost?

Yes.

 

[boxerfan88]

I tried looking for good SUBs with digital IN and the only one I saw was genelec.
Did I miss something?
Why don't they all support digital-in instead of performing ADC?

Been there and tried that (via a second USB DAC to drive the subwoofer) ... it won't work well coz the subwoofer DAC clock is not synchronized with the mains DAC clock.
Most likely we will see weird phasing issues around the crossover region which will impact the frequency response in the crossover region.
When I tested with an analog crossover (dbx 234XL) I had no such phasing problem.

Refer to post #36 here: https://www.audiosciencereview.com/forum/index.php?threads/vb-matrix.48989/page-2#post-1766565

In the end, I gave up running two separate DACs, and went with a single Topping 8ch DAC to drive my 2.1 system.

.

 

[SigbergAudio]

Regarding that last point, why is the AD/DA conversion within a subwoofer DSP is for all practical purposes transparent?
Is it because distortion in the low frequencies is hard to notice like Vacceo said?
If this is the case, a basic DAC installed between the digital source and the SUB could eliminate the need for a digital in for a low cost?

​

It is because AD/DA conversions in general are transparent. If your question was about an active speaker, the answer would be the same.

 

[gabrielb]

Again, what is a "lossless crossover"?


No, it's because modern electronic AD and DA converters are audibly transparent.


Yes.

If you reverse the crossover merging the 2 streams into a single stream it will be identical to the original stream.
The same can't be said about analog crossover, but I guess it can be close enough it is *virtually* the same.

 

[Hear Here]

A few reasons I can think of:

A) There are not a lot of sources out there that could provide the subwoofer with digital input
B) Derived from A, very few customers require this functionality, so there is little point to implementing it
C) The AD/DA conversion within a subwoofer DSP is for all practical purposes transparent, so you don't achieve any tangible benefit.

I wonder how many of your points are valid.

A) Most DACs, preamps and integrateds that accept digital sources include a digital output - usually coax and optical and occasionally AES/EBU
B) Well, if customers start with a digital source and wants a sub with DSP, he should be looking for a digital in on the subs
C) You underestimate the conversions involved. The initial digital signal needs a DAC before it reaches the sub, then the sub needs an ADC and another DAC - 3 conversions!

The fewer conversions the better for the signal - and less costly.

The more I think about it, the more valid the OP's question is - if the sub uses DSP.

 

[SigbergAudio]

I wonder how many of your points are valid.

A) Most DACs, preamps and integrateds that accept digital sources include a digital output - usually coax and optical and occasionally AES/EBU
B) Well, if customers start with a digital source and wants a sub with DSP, he should be looking for a digital in on the subs
C) You underestimate the conversions involved. The initial digital signal needs a DAC before it reaches the sub, then the sub needs an ADC and another DAC - 3 conversions!

The fewer conversions the better for the signal - and less costly.

The more I think about it, the more valid the OP's question is - if the sub uses DSP.

A) The numbers are increasing, but not that many have a variable digital output (fixed digital output will not work).
B) Due to C, not really.
C) I said AD/DA conversion, so that's the last two of your three. And yes, it's a given that there's typically a DAC in front of it. So I'm not underestimating or forgetting anything. Still transparent.

 

[gabrielb]

I wonder how many of your points are valid.

A) Most DACs, preamps and integrateds that accept digital sources include a digital output - usually coax and optical and occasionally AES/EBU

The question who are the customers buying the SUBs?
I guess most are home theater surround system then the SUB input will arrive from the AV receiver doing all DAC/Delays/Crossovers ...
I wonder how big a market is SUBs for 2.1 audio system where digital out is available (my guess, probably a niche market)

 

[SigbergAudio]

The question who are the customers buying the SUBs?
I guess most are home theater surround system then the SUB input will arrive from the AV receiver doing all DAC/Delays/Crossovers ...
I wonder how big a market is SUBs for 2.1 audio system where digital out is available (my guess, probably a niche market)

Actually a significant number of stereo users also have subs. Based on experience + if I remember correctly from a couple of surveys done, probably easy 30% at least. REL which is a pretty well known sub manufacturer makes subs primarily for music. As do we.

 

[gabrielb]

Actually a significant number of stereo users also have subs. Based on experience + if I remember correctly from a couple of surveys done, probably easy 30% at least. REL which is a pretty well known sub manufacturer makes subs primarily for music. As do we.

In that case my question returns - why don't we see more SUBs with digital-in as the vast majority of stereo users got digital out on their DAC/PRE?
Why pay the extra cycle of DAC and ADC?

 

[unpluggged]

the vast majority of stereo users got digital out on their DAC/PRE?

Where did you get these statistics?