[AmpDesigner333]

Check these out....

Logitech Sqeezebox Touch based demo system using Maraschino Cherry amps and DAC DAC:




Dell Latitude Tablet (Windows 8.1 Pro) based demo system using Maraschino Cherry amps and DAC DAC:




More on these systems later....

[SteveMiller]

I cant make as nice a picture as Tommy did above, but here's a configuration for Apple people.

iMac -> itunes -> Halide Bridge USB-to-SPDIF -> DAC DAC -> DAC Marschino Amplifiers -> Speakers    =   

[AmpDesigner333]

Once the MINT is available, the two amplifiers can be one (same with the dual power supplies)....

[JLM]

I cant make as nice a picture as Tommy did above, but here's a configuration for Apple people.

iMac -> itunes -> Halide Bridge USB-to-SPDIF -> DAC DAC -> DAC Marschino Amplifiers -> Speakers    =   

Where's the volume control?

[Folsom]

What are your power supplies?

[AmpDesigner333]

Where's the volume control?

Done digitally before the DAC.  Thanks for your post.

[JLM]

Done digitally before the DAC.  Thanks for your post.

Thanks for the quick reply.  I thought most pooh-poohed any digital volume controls, except like the NAD 32-bit.  How can I do that with my MacBook?

I've always understood that digital cuts off the peaks as volume in turned down versus scaling all signals in the same ratio.

[aldcoll]

How is the Volume controlled digitally?  If done in the squeezebox you are removing data and that is a major loss of sound/quality or should I say Quality/sound.

Alan

[AmpDesigner333]

How is the Volume controlled digitally?  If done in the squeezebox you are removing data and that is a major loss of sound/quality or should I say Quality/sound.

Alan

Alan,

What is the resolution of their volume control?  I remember reading it's 32-bit.  A pretty robust search didn't yield this answer.

Think of it this way....  If the device is capable of 24-bit audio, the output is 24-bit resolution, attenuated or not.  32 bits means that means you still get 24-bit resolution at nearly 50dB down (1/256 attenuation, equivalent to shifting down 8 bits).  That's almost 145dB of DNR left AFTER the attenuation.  There may be a common misconception that digital volume is bad, but it's theoretically close to perfect if done properly.  I searched around and found so many comments from obviously misinformed people, putting down digital volume control.

Digital volume doesn't require history (data storage) to work (although it can be used to reduce the computational effort), so it's usually a simple divide operation(!), and can be executed identically for each sample.  Of course, the DAC must be very good as well as what it feeds, which in the case of an amplifier, there's no preamp to add noise in the first place.

ESS did a presentation on this several years ago:
http://www.esstech.com/files/3014/4095/4308/digital-vs-analog-volume-control.pdf
"As long as the analog volume control has a noise floor better than the DAC noise floor, the analog one will win"

We should allow Logic to answer about their algorithm....

Thanks.

-Tommy O

[aldcoll]

Okay you have me beat for tech.  I looked this whole debate over and it was discussed here on AC a while back and my first line answer of Google search pulls up WIKI Logitech Squeezebox and they say DON"T DO IT. 

There is also a long and old postings on Slim Forums and a few associated sites.   It was reading these sites a year or two back that I came to the Non digital Volume thought.

I also did a month or more home test to see what I thought of my setup and no Pre Amp Squeezebox to Amp section of a NAD 7400 and another SS amp also.   First of all the Digital Volume is Fast so don't drop the dammed remote in the side of the chair cushion.

DON'T ever trust that the last person turned the volume down before they shut the equipment down.

And with about four of us listening for a few hours we truly thought the sound sucked.   Dead lifeless at low volumes.  We even ran the Squeezbox into a couple DAC's and no real help.

Just my summer of playing a while back.  I personally hopped it would work as I am looking for the least amount of color added to the recorded material for what I can afford I might ad.

Alan

[AmpDesigner333]

Okay you have me beat for tech.  I looked this whole debate over and it was discussed here on AC a while back and my first line answer of Google search pulls up WIKI Logitech Squeezebox and they say DON"T DO IT. 

There is also a long and old postings on Slim Forums and a few associated sites.   It was reading these sites a year or two back that I came to the Non digital Volume thought.

I also did a month or more home test to see what I thought of my setup and no Pre Amp Squeezebox to Amp section of a NAD 7400 and another SS amp also.   First of all the Digital Volume is Fast so don't drop the dammed remote in the side of the chair cushion.

DON'T ever trust that the last person turned the volume down before they shut the equipment down.

And with about four of us listening for a few hours we truly thought the sound sucked.   Dead lifeless at low volumes.  We even ran the Squeezbox into a couple DAC's and no real help.

Just my summer of playing a while back.  I personally hopped it would work as I am looking for the least amount of color added to the recorded material for what I can afford I might ad.

Alan

Alan,
Media players like JRiver have very good volume controls, but you need great DNR from the DAC to make it all work.  The DAC DAC HS version is about 125dB on the daughter card prototype and we expect a little more when it's all on the board.  Interesting topic for sure.  You can use a preamp if desired, of course, but that typically adds much more to the signal path.  I'll search again for info on the Logitech volume control and I'll try to ask through the website.  I'm not expecting a speedy answer considering the holiday season....  Thanks again.
-Tommy

[mfsoa]

I think there's a distinction between what the squeezeboxen would do with a 16 bit signal (start losing data right away upon digital attenuation) vs. what JRiver would do w/ a 24 (or more) bit signal where it can toss bits without significantly reducing quality.

I don't know much about the math behind it (obviously!) but I've been told that when a 16 bit word is processed via a 24 bit system that 8 "placeholder" bits, w/ no information, are added and that these placeholders can be removed to attenuate w/out data loss.

Tommy, could you add some different gain levels to the output of the DACDAC so that one has the choice of how much digital attenuation to use? But then why not go one step further and use analog volume? (At no additional cost to the consumer he he  ).

I am wary of putting 16 bits of digital ones through my Maraschinos straight to my Revels!

[AmpDesigner333]

I think there's a distinction between what the squeezeboxen would do with a 16 bit signal (start losing data right away upon digital attenuation) vs. what JRiver would do w/ a 24 (or more) bit signal where it can toss bits without significantly reducing quality.

I don't know much about the math behind it (obviously!) but I've been told that when a 16 bit word is processed via a 24 bit system that 8 "placeholder" bits, w/ no information, are added and that these placeholders can be removed to attenuate w/out data loss.

Tommy, could you add some different gain levels to the output of the DACDAC so that one has the choice of how much digital attenuation to use? But then why not go one step further and use analog volume? (At no additional cost to the consumer he he  ).

I am wary of putting 16 bits of digital ones through my Maraschinos straight to my Revels!

Analog volume control = longer signal path. This was a compromise we didn't want. The output signal in the TL version of DAC DAC only goes through one gain stage to the connector. This is the shortest path possible while allowing dual differential balanced outputs.

Bottom line is that the DAC DAC has sufficient dynamic range to make digital volume work quite well, plus you can always use a preamp if desired.  Once you add to the signal path, you can't undo the added noise and distortion.

Thanks.

[SteveMiller]

If I may add 2c worth....

Having been lucky enough to enjoy and currently be listening to a TL DACDAC driving Maraschinos and 101db speakers, I'd like to chime in and describe what I found as regards the volume control aspect of it's existence. In the beginning I was stressing a lot about it.  I use an iMac as source. I was previously using a Sabre dac with digital volume control to drive the Maraschino amps.  Using that particular dac's digital volume control was way better at the time, than using the very well reviewed passive preamp I had previously thought was very good.  I eliminated that preamp when I found that Maraschinos proved a perfect load for my old DAC. They also showed the shortcomings of this very good passive.  So that's part one.  In a system that has sufficient gain already, and a well designed digital volume control, eliminating the extra devices, interconnects, and path length is a good thing. I'm talking about equipment that won reviews and reviewers themselves purchased.  My system sounded better without it once I trusted the digital attenuation.

Fast forward, to Tommy letting me try DACDAC. Now, i lost beloved digital volume control of my previous dac and I panicked.  But here's the thing. The DACDAC fed directly to Maraschino amps was good.  I mean GOOD!  so much so that I tried several other preamps trying to get a volume control that let all the goodness of that direct connection of DACDAC shine.  But none could.  I read the reviews, thought ok...this one will do it, and then no.. it didn't.  I'm talking $3000-$5000 preamps here.  Every one rounded off the edges and dulled the amazing life out of what DACDAC can breath into your system...  Even the iTunes volume control ( which you'll be surprised how good iTunes can sound with this DACDAC ) is wonderful.  And I can tell you, with material up to CD or even 24bit recordings, there is NO audible loss of resolution using even just iTunes volume control through DACDAC.

Users who perceive a problem with digital volume control I believe, are hearing the noise floor and limitations of their dac, or low level insensitivity elsewhere in their system. You will be very hard pressed to find a pre-amp that doesn't detract from the strengths of DACDAC. 

Keep in mind, that my findings are in my system.  But I wholeheartedly agree with Tommy's findings and this product pairing.  I did end up finding a very good passive TVC that was up to the status for the DACDAC/Maraschino pair. but it was a long road.  And even then, if Im home alone, the direct connection is better. 

One of the things that sooooo good about DACDAC is the super short signal path.  Putting anything in the way does do just that.... Having said the above, not every dac has the drive to connect directly and do it well.  And not every amp input is sensitive enough to be driven directly.  And not every system has enough gain to drive the speaker load without a pre.   But if you use a DACDAC and Tommy's Maraschino amps you have a perfect pairing.  and I promise you'll spend less here than other systems, but most importantly you'll have that elusive sound of your music being ALIVE. 

[jseipp]

SteveMiller --

Thank you for taking the time to share the extremely thorough discussion of your extremely thorough experience with the issue of digital volume adjustment.  I am among those who have the Maraschinos and am looking very forward to the DAC DAC.  It's been my experience to trust Tommy when it comes to the choices he makes in designing his equipment, and to appreciate his coherent explanations for how it all works, but it is always nice to have another point of reference, especially in what amounts to unfamiliar territory -- non-analog volume control -- for many.

The upshot to me is that the DAC DAC promises to be a very special part of a dead-simple system that lets nothing get in the way of the music. 
 

Again, thanks for taking the time to share!     

[JLM]

Had a Squeeze Box 2 (SB2) years ago but the glitches were insufferable.  Anyway, do we need a separate thread to discuss non SB sources?

Getting lost in undefined abbreviations (DNR, TL version DACDAC, DACDAC HS version).  As an open discussion, please define.

I’m all about simple and short, in fact I removed the binding posts from my single driver speakers just to get a more pure connection.  With many audiophiles using computer sources why not have a built-in USB/SPDIF converter at least as an extra cost option so we can save cable/connectors, and trying to find the optimum converter (that you or a 3rd party should be able to build in cheaper)?


Regarding software based volume controls:

-   Between maximum listening levels (jazz/classical being 105 dB) and a typical quiet noise floor of say 35 dB, we need about 70 dB of headroom
-   The theoretical max headroom would be about 100 dB (difference between the threshold of pain being roughly 130 dB and a really quiet room of 30 dB)
-   Redbook and higher resolutions have those numbers covered, as do any modern DAC, so not an issue
-   Speaker efficiency and proper pre/power amp matching (nearly all of which use a standard 2 volt signal) are also not at issue
-   But like Alan, I’ve experienced severe compression using now ancient digital volume controls
-   Tommy mentioned 50 dB headroom between 32 bit software based volume controls and 24 bit material  (this appears to not be enough)
-   But what playback software has 32 bit volume controls?
-   Don’t know about most readers, but a short/simple slide control is not particularly easy/friendly to use
-   And what is the actual bit rate that readily available music actually use?  (I’ve read it’s 18.5 and of course Redbook being 16 bit based would be lower.)
-   Thus, if my math is right, 32 bit – 18.5 bit would provide over 100 dB of headroom before clipping so that should be enough (for now)

So it seems to me that the real solution is to verify which softwares have 32 bit based volume controls (hopefully with some sort of fine adjustment and numerical dB display available).

[SteveMiller]

Regarding abbreviations.

DACDAC - Digital Amplifier Company's Digital to Analog Convertor

It comes in 2 versions. TL is TubeLike.   And HS is HighSpec. 

Initially Tommy found a way to drastically reduce parts count and shorten the signal path length over traditional and even manufacturer recommended implementations of the BurrBrown chips. This is TL.   It's simply awesome. It's fast, clean, dynamic, but the best word I can use is Alive.  It's like there's life and excitement inside the music that I never could get at before. It's not about bass, tone, or treble.  It even goes beyond measurement ability to capture what happens here.  I've had a lot of good gear. But this just sounds right.  Less stuff between the microphone and your speakers. 

HS version is a little different.  I haven't heard it (yet) but in this case Tommy pursued measurements and achieved astonishingly low distortion and sota ( StateOfTheArt ) Signal to Noise Ratio (SNR)

[AmpDesigner333]

Had a Squeeze Box 2 (SB2) years ago but the glitches were insufferable.  Anyway, do we need a separate thread to discuss non SB sources?

Getting lost in undefined abbreviations (DNR, TL version DACDAC, DACDAC HS version).  As an open discussion, please define.

I’m all about simple and short, in fact I removed the binding posts from my single driver speakers just to get a more pure connection.  With many audiophiles using computer sources why not have a built-in USB/SPDIF converter at least as an extra cost option so we can save cable/connectors, and trying to find the optimum converter (that you or a 3rd party should be able to build in cheaper)?


Regarding software based volume controls:

-   Between maximum listening levels (jazz/classical being 105 dB) and a typical quiet noise floor of say 35 dB, we need about 70 dB of headroom
-   The theoretical max headroom would be about 100 dB (difference between the threshold of pain being roughly 130 dB and a really quiet room of 30 dB)
-   Redbook and higher resolutions have those numbers covered, as do any modern DAC, so not an issue
-   Speaker efficiency and proper pre/power amp matching (nearly all of which use a standard 2 volt signal) are also not at issue
-   But like Alan, I’ve experienced severe compression using now ancient digital volume controls
-   Tommy mentioned 50 dB headroom between 32 bit software based volume controls and 24 bit material  (this appears to not be enough)
-   But what playback software has 32 bit volume controls?
-   Don’t know about most readers, but a short/simple slide control is not particularly easy/friendly to use
-   And what is the actual bit rate that readily available music actually use?  (I’ve read it’s 18.5 and of course Redbook being 16 bit based would be lower.)
-   Thus, if my math is right, 32 bit – 18.5 bit would provide over 100 dB of headroom before clipping so that should be enough (for now)

So it seems to me that the real solution is to verify which softwares have 32 bit based volume controls (hopefully with some sort of fine adjustment and numerical dB display available).

First, thanks to Steve for his kind words and acronym explanations.  I have a tendency to define stuff once, then go on using the acronyms.

Second, I said at nearly 50dB down a 32-bit attenuator will still have 24 bit resolution.  (32-8=24)

Third, I find it interesting that media players, both stand alone and the computer software type, don't talk about their volume control resolution.  It's a simple number.  Well, some do, but few.

Fourth, there are two diagrams at the beginning of this thread. The "other" system is PC based.  I was hedging on leaving out the Squeezebox Touch one, but it shows a direct SPDIF connection, and that kind of explains the extra hardware in the PC case.

[AmpDesigner333]

JRiver has a 64-bit volume control????
http://wiki.jriver.com/index.php/Volume

Seems overkill, but maybe they just do everything with 64-bit resolution anyway.

Can anyone verify this?

[AmpDesigner333]

By the way, the DAC DAC thread has lots of info, including features/specs:
http://www.audiocircle.com/index.php?topic=138311.0

Also, the reason why DAC DAC has SPDIF input only is disclosed here:
http://www.audiocircle.com/index.php?topic=137912.0

There will probably be a separate thread soon for the Kickstarter.

Keeping these sub-topics separate makes it easier to find information.  Thanks.