Dithered Volume Control [Released in Roon 1.2]

Any updates on plans to add a high-quality dithered volume to Roon (eg using iZotope).

I assume this would include an upsampling option too.

In combination with the existing exclusive-mode, this would be great for basic, high-quality playback.

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Shouldn’t it be down to the DAC to control volume in the analogue domain?
I’m not a fan of digital attenuation as it reduces resolution.

Mostly, I’d agree: all things being equal, volume is best controlled in the analog domain.

But:

  1. Unfortunately, this isn’t always an option. My Peachtree iDac just doesn’t support digital volume. (My Conrad Johnson tube integrated-amp doesn’t have any remote control at all.) So, the only way I can adjust the volume is to either: get up, walk across the room, and adjust the amp’s “Volume” dial directly (gasp!!!); or, adjust it digitally in front of all that (using the Roon controls or equivalent).

  2. all things aren’t equal. Tidal and my music collection is (mostly) all Redbook (16bit, 44Khz), while my iDac has digital bandwidth up to 24bit 96kHz.

I think the extra headroom from (2) can be used to
i. simply add volume without losing resolution (eg taking 16/44k in, and streaming 24bit/44k out to the DAC): that can give 8 bits of volume, without losing any resolution from the 16-bit samples.
ii. upsampling the whole stream is apparently very defensible (eg to 24bit 96k) - as our CPU’s can frequently do this better than most DACs (Audirvana and HQPlayer provide two examples of this) … if you upsample, I think you can can have dithered volume control in the bargain. (?)

That’s my understanding, anyway… I admit these issues get technical quickly.

My fundamental problem is just that my DAC doesn’t offer digital volume control.

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I know this has been requested before and I have emailed about it, but was asked to post here.

Please add a high quality dithered volume control, such as offered by Amarra, Pure Music, etc. When listening through my headphone setup, I do not have a remote control for volume, so must make volume adjustments through my music player app.

I don’t want to throw away resolution when attenuating volume.

My trial is ending soon and this is a deal killer for me. Could you please give an indication of if/when this feature will be added? Thanks.

Hi, just wondering what DAC are you using?

Hi, Carl,

My main DAC is an Ayre Codex.

Re:

That is the whole point behind a dithered volume control–it allows you to attenuate volume without reducing resolution.

My understanding of dithering is not that it prevents loss of resolution (not something that can be avoided in a quantized system), but that it minimizes the perceived loss of sound quality due to the inevitable loss of resolution.

My understanding is you’re still doing division on integers, and having integer results, you’re just injecting pseudo-randomized noise into the signal to deal with the psychoacoustics.

None of which is to say it doesn’t work well. It’s used in all sorts of domains beyond audio, including non-perceptual ones.

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Hi, Ankimo,

I believe that you are indeed correct in that technically there is an actual truncation of bits in a dithered volume control. But as you say, in the real world it still works.

My understanding is that as long as the attenuation is not extreme, with a dithered volume control we are throwing away bits that only consist of noise. With a 24-bit DAC using a dithered volume control, even if we attenuate 18 dbs, we still have a 21 bit signal–which will exceed the S/N of the rest of our audio system.

Good info from Daniel Weiss of Weiss Audio is here:

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Based on this post from the Roon team and given that your Ayre DAC already has a digital volume control would it not be easier/better for the Ayre driver to use the separate volume signal Roon is already sending?

Unless you can disable the Ayre volume control adjusting the volume twice seems like it would introduce some loss in information.

Hi, Philr,

I agree with you that, unlike heads, two volume controls are not better than one.

But the Ayre volume control has no remote control. So when listening with headphones, I sparingly attenuate the volume through the software player volume control.

Using Amarra, which features a dithered volume control, sounds great.

Dithered volume control is really a feature that Roon needs.

As I mentioned Roon already has a volume control why can’t the Ayre use that?

Hi, Phil,

The Ayre Codex will not allow external software to take control of the volume function of the DAC chip (if that’s what you’re referring to). Nor will the QB9.

While some DACs aimed at the portable audio market (and some in the pro audio space) allow third-party software to take control of the volume function on the DAC chip, I’m not aware of any designed for the home High End audio market that allows this function.

@Mike I don’t want to throw away resolution when attenuating volume and my trial is ending soon and this is a deal killer for me. Could you please give an indication of if/when this feature will be added? Thanks.

I think there are many audiophile DAC’s that allow software control of volume - but, more to the point of this thread, there are, unfortunately, many that don’t - eg my Peachtree, your Ayre (I guess), etc.

I don’t think this is uncommon, which is why this feature is important…

(Of course, it’s also important to be able to /disable/ any gain-controls in Roon - to move a bit-perfect sample downstream, with no risk of losing resolution, or adding noise, etc. But, that feature already exists in Roon…)

+1 on dithered VC

+1 to dithered volume control!

+1 on dithered volume control

+1 on good dithered volume control as an option

I do not think it is to clear on this forum but I am in the business and run Computer Audio Design. Here is my opinion on this:

Yes, volume control in the digital domain does lose some bit depth. A few years ago volume control in the digital domain just truncated the least significant bits. To my ears it was not very good. But over the last 2 -3 years we are seeing companies coming out with dithered volume control that to me works incredibly well.

I think when we talk about this topic there is an assumption by many that volume control in the analogue world is perfect. Well unfortunately it is not. I am not saying that software digital dithered volume control is perfect either, but what you can get for the money is extremely good.

If you have a separate preamplifier or some way of driving your amplifier directly try the following:

Get some software that has good dithered volume control and compare that against your preamplifier. Now you have to be very very careful when you do this because you have the possibility of blowing up your speakers and/or your amplifier! Before you change any hardware get the volume control in the software working. Once you have that figured out turn the volume to minimum. Now turn your amplifier and preamplifier off. Then connect your DAC directly to the amplifier and turn the amp on. Now slowly turn the volume up.

Some DACs will not have the proper output impedance to work with your amplifier and you may not get good results. But now you can A/B digital volume control against analogue. This setup will typically show you that dithered volume control is amazingly good.

I have done this many times with our dealers, reviewers and in trade shows. Most of the time the sound quality is substantially better with digital dithered volume control. Taking a preamplifier out of the signal chain removes a lot of hardware from the signal path. A preamplifiers does 3 things:

  1. Gives volume control

  2. Allows you to connect more than one device to your amplifier

  3. Hopefully gives correct impedance matching for your amplifier

If you can live without 2 & 3 you might get a step up in sound quality for no or very little money.

Scott

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Good points, Scott.

My Simaudio Moon integrated has a well implemented volume control with remote, so I prefer to use that (I also need it for source switching).

But given the choice between a simple potentiometer and a well designed dithered digital volume control, The digital would be the better choice.

Unfortunately, when listening through my headphone amp, I don’t have a choice–since my headphone amp lacks remote volume control, I need to adjust it digitally through my software player.

For me, HQPlayer integration now makes this feature unnecessary/moot…

Hi, jimmyb,

A couple of thoughts:

The simplest solution is often best. While I’m in the process of testing HQP in my system, I’d like the option of playback (with dithered digital volume) through a single program.

Also, while I’ve owned DACs in the past that I would have been eager to try to “improve” via the filter options in HQP, I really don’t feel the need with my current DAC (Ayre Codex). With some DACs, such as Chord’s, the designer’s proprietary filters are really what they’re all about, and owners may not want/need HQP’s filters.