Digital vs. analogue volume control for digital monitors

[ChrisFromDublin]

I’m preparing for the arrival of my Genelec 8351A active digital studio monitors. They accept both a digital signal and an analogue signal.

 

My dealer says I’ll get the best result by feeding them an analogue signal, because I can then adjust the volume in the analogue domain, which doesn’t reduce the bit depth of the signal, as any digital volume control will do. But I’d like a second opinion on this.

 

Basically, I have these two options:

 

A: Send digital signal directly to the monitor. The volume control will then be handled in the digital domain, either inside my computer or by the “Genelec Loudspeaker Manager” software inside the monitor.

 

B: Convert the digital signal from my computer to analogue -> Control volume with an old-fashioned analogue pre-amp -> use analogue input on the monitor, after which the signal will be converted back to digital inside the monitor.

 

Does anybody have experiences with the audio quality differences between these two approaches?

Will I be able to hear the difference?

If I had to guess, I would imagine that the all-digital approach might retain more attack, but be less smooth sounding, or perhaps a bit blurry due to the need for more dither. And that the analogue approach might introduce slight changes to the overall tone (which would be of no importance because they would be corrected by Genelec Loudspeaker Manager Digital Room Correction.) But I have no experience with this.

 

I’m aware that it must be of greatest importance which kind of DAC and analogue volume control I use. At the moment I’m using a Benchmark DAC1 PRE, which is both my DAC and my volume control/pre-amp. The music I listen to is 16-bit standard CD quality upsampled to 24-bit in my computer.

 

It must also be of great importance which analogue-to-digital converter the Genelec 83xx-series uses. I haven't been able to find any information about chipsets, shielding etc.; nor tests comparing the quality of the two inputs.

 

Thank you for any help.

[Audio_ELF]

I would suggest that digital direct to the speakers will be better. I always have a KISS philosophy so why convert to analogue just to have to convert back to digital.

 

Digital volume control also has many advantages over analogue.

 

Having said that ... why not try the digital, and also compare to the analogue?

 

Eloise

 

(I'm sure Pete will be along soon as the resident Genelec expert)

[Miska]

B: Convert the digital signal from my computer to analogue -> Control volume with an old-fashioned analogue pre-amp -> use analogue input on the monitor, after which the signal will be converted back to digital inside the monitor.

 

Back and forth digital conversion is bad. You end up limiting dynamic by adding extra analog noise this way.

 

If your source material is mostly 16-bit, with 24-bit output you can lower volume to -48 dB in digital domain without any loss in dynamic range. In analog domain you would have dynamic range limited by the analog noise floor earlier. In addition if you can upsample to 176.4/192k rates (assuming those monitors accept such input) you can also utilize noise shaping to increase dynamic range further across the audio band. Just make sure you use digital volume with proper dither applied.

 

One thing to note is that with a software based volume control you need to be very careful to avoid accidental volume surprises, and if possible with the software you use, set limit for the maximum volume. Good thing with traditional non-software controlled analog volume is that it is not so easy to have volume accidents...

[DigiPete]

Reposted from the Genelec community Forum:

http://www.community.genelec.com/forum/viewtopic.php?f=4&t=1716&sid=7fd4a0d796352144459f4e2c1480f709

 

 

 

Congratulations on the 8351's!

 

I usually run my 8260's at -40dB through GLM and I have always been blown away by the effortless and naturally detailed sound.

Running all digital cuts all the usual losses and colorations from the signal chain - isn't that is the whole point?

 

I have never considered using a DAC with Genelcs, so I can't tell you how pristine a DAC you would need.

Then again: I thrust the professionals at Genelec over the amateurs and audiophools.

I would probably fire that dealer !!!

 

For perspective, you can attenuate more than -45dB on the extra zeroes that you just put in from 16 -> 24 bit.

[DigiPete]

The real question here is: how much attenuation is too much on the Genelecs?

 

This is actually a real concern, as the top SAM Genelecs are usually way more powerful than needed.

 

"Sufficiently powerful for any use" as Rolles Royce would put it.

Insane amounts of headroom I would say.

 

Genelec generally refuses to share or discuss technical details of the electronic bowls of their monitors.

Thus sadly I have no better answer to the OP's question.

[ChrisFromDublin]

Thank you, everybody! … Yes, theoretically, all of you are right!

 

It doesn’t make sense to convert to analog, and then back again to digital. But the dealer who is of a different opinion is one of the biggest in Europe. I imagine they have listened to more active speakers than any of us, and probably also to each of them in more setups than any of us. I was looking for actual experience with comparing the digital to the semi-digital setup, not just logical thinking about how must be. (Then again, he might just be a temp, speaking nonsense.)

 

I already subscribe to every one of DigiPete’s threads. :-) I wanted to hear from others with digital active studio monitor experience.

 

In a few weeks time, when I get back to my apartment, the monitors will have arrived, and I’ll slowly start doing some experimentation on my own. I have a stressful spring and summer ahead of me, but at some point you’ll hear my two cents.

[DigiPete]

Off topic I would welcome a shootout between your new 8351's and a pair of my 8260's.

 

I'll even bring what ever is your favorite beverage ;-)

[ChrisFromDublin]

Good idea! ... Except, it would be difficult to get your system from Scandinavia to the island of Malta in the Mediterranean, where I live.

[nyatousga]

Just make sure you use digital volume with proper dither applied.

[ChrisFromDublin]

@nyatousga: How do I make sure that I do that?

[20hertz]

Just use the GLM provided for volume control. I run 8260s with some of the best Vinyl playback gear around and always use the GLM as volume control. The entire benefit of using DSP Genelec's is the simplicity and outstanding accuracy they provide, no need to make the process messy using old school methods. I listen and work on a lot of high end systems and the 8260,s cant be beat easily.

[DigiPete]

Just make sure you use digital volume with proper dither applied.

 

Any reason the industry leader in digital input monitors suddenly should not be trusted to do proper dithering?

[Miska]

Any reason the industry leader in digital input monitors suddenly should not be trusted to do proper dithering?

 

I think this is more about using some external volume control rather than built-in (I don't know if there's such).

 

In many cases, when a device with built-in DAC provides volume control, the offered volume control is the on-DAC-chip one. On the other hand, many digital engineers believe it is not worth dithering 24-bit due to low level of the errors so you cannot take dither as granted. Proper implementation is another matter. Measuring the built-in electronics would tell something. (I'd be curious to know what DAC chip they use)

 

Being "industry leader" is not a valid technical argument...

[ChrisFromDublin]

I run 8260s with some of the best Vinyl playback gear around and always use the GLM as volume control. The entire benefit of using DSP Genelec's is the simplicity and outstanding accuracy they provide, no need to make the process messy using old school methods. I listen and work on a lot of high end systems and the 8260,s cant be beat easily.

 

@20hertz:

Your setup intrigues me: In your super vinyl system you manage to avoid digitization all the way to the speakers. And then you’ve chosen digital monitors for this system. Can you tell me more about your thoughts behind this?

I would have imagined that you would prefer older analog monitors from Genelec which would allow you to go analog also inside the monitors.

 

I attempted to start a thread about this on the Genelec website, but it didn’t really catch on.

Genelec Community Forum • View topic - How come nobody hates digital monitors?

 

Maybe your experiences merits their own thread here on ComputerAudiophile?

[Jabs1542]

This offers him a nearly perfect digital crossover along with amplifier biasing per driver plus DSP for room correction and such. It's pretty slick once you swallow the concept of A>D and then D>A (because the drivers themselves receive analog voltages). This philosophy is getting pretty common, my speakers have some of this as well.

[20hertz]

@20hertz:

Your setup intrigues me: In your super vinyl system you manage to avoid digitization all the way to the speakers. And then you’ve chosen digital monitors for this system. Can you tell me more about your thoughts behind this?

 

I find the improved midrange accuracy provided by the DSP room correction, and especially the seamless Genelec coax mid/tweeter extremely beneficial to my work. I am sure some highend analogue systems retain more of the vinyl magic but at a greater cost. The 8260s provide a tri-amped, DSP room corrected all in one speaker package, flat from 18 hertz, at a very reasonable cost.

 

When I run a digital frontend the Genelecs are just so simple to use, they accept SPDIF as well as AES, just swap the connector on the cable and use GLM for volume and room correction. For analogue playback I run from the phono stage direct into the spakers and have the best of both worlds.

[esldude]

@20hertz:

Your setup intrigues me: In your super vinyl system you manage to avoid digitization all the way to the speakers. And then you’ve chosen digital monitors for this system. Can you tell me more about your thoughts behind this?

I would have imagined that you would prefer older analog monitors from Genelec which would allow you to go analog also inside the monitors.

 

I attempted to start a thread about this on the Genelec website, but it didn’t really catch on.

Genelec Community Forum • View topic - How come nobody hates digital monitors?

 

Maybe your experiences merits their own thread here on ComputerAudiophile?

 

In another reply to your comment, JABS1542 mentioned swallowing the concept of A>D, and then D>A. That is a very perceptive comment.

 

For a generation now audiophiles have been sold the idea digital has a bad sound of its own. To digitize 'pristine' analog signals was to diminish their goodness. The idea doesn't hold truth anymore.

 

I convinced a friend to digitize straight out of his analog phono stage, and then handle everything digitally from there on out to the speakers. We were doing room correction too. How did I convince him of this? It wasn't by lying to him, or tricking him. I set things up so it could be done both ways. I also did digital recording of his analog. He could hear for himself the digital demons were no more real than other demons about which tales are told. The result (whether room correction was engaged or not) was digitizing as early as possible gave him the best analog performance he had ever attained. So the fear of bad sound when you digitize is unwarranted.

 

As said, if you have swallowed the concept of A>D then D>A, then you don't have any reason to hate, distrust or cast questioning glances at digital monitors or other digital gear.

 

BTW, the concept of AD followed by DA isn't that such a conversion is wholly perfect. Rather that it is very, very good, it allows some useful DSP in some situations not possible otherwise, and overall any cost it exacts is quite small while the benefits versus full analog are quite considerable. Simply put you gain much more than you loose.