LUMIN Music - Leedh Processing

Specifically what I mean with my comment about integer vs. floating point is that, just as in graphics, making a graphical element translucent by an arbitrary ratio used to be very advanced and available only in the most sophisticated software like Photoshop, today it’s used in many web pages, viewable on a phone. Similarly, in audio, Roon has enough compute power do do all kinds of processing, from DSP room correction to simple volume control, in 64 bit floating point.

It is true that at the end, the DACs don’t take floating point so Roon has to render the result in 32-bit or 24-bit integer. But that’s true for Photoshop too, the printers typically don’t take floating point, but the integer precision is sufficient to faithfully render images that have been created with floating point.

So that would be my concern here: we do have a technique that works really well provided you have enough compute power: Roon doing the processing in floating point and then rendering the result in 24-bit or 32-bit integer for the DAC. But as you say, endpoint devices may not have the compute power to do that.

So my question is, what is the purpose here?

  1. To allow volume control in a limited-power digital device while avoiding the limitations of primitive digital implementations?
  2. Is the claim that the integer-fraction processing sounds better than the floating point processing in Roon?

To put it in Lumin terms, one situation is when you have a signal from some primitive source, a CD player or an internet stream: does this provide improved sound quality?

The other situation is when playing Roon: as you say, Roon can be set up so that a volume control change in Roon leaves the RAAT signal unchanged and Roon tells the Lumin box what volume is desired, but Roon can be instantly changed to do its own volume control (in floating point) and leave the Lumin box at 100 %. So the question for this forum would be, how would those two configurations compare?

Here’s what I am seeing since the update…!
The DSP number seems to be fixed and can’t be changed.

The claim is that, as with any audio product, it sounds better.

It you accept the view (in the whitepaper) that DAC output can do no more than 21 bit of resolution (see Stereophile measurements), it may be a little easier to understand the rationale of it.

As with another controversial format, we give users the choice to listen for themselves and make their own decisions whether it sounds better to them. We even added a setting in the app for users to easily switch between Leedh Processing Volume and the standard implementation, e.g. in ES9038PRO in Lumin X1, ES9028PRO in Lumin T2, etc. We do not force the use of this volume, in the same way that we do not force the use of the filter associated with the controversial format for music not in that format - the same cannot be said for many DAC supporting that format.

If users find it to sound better, that’s great, as we paid money and time for it.

Even if they don’t find it to sound better, I also think we served a valuable purpose here.


I certainly am not suggesting any criticism of your decision here. And I won’t have an opportunity to evaluate it in a Lumin box anytime soon, don’t need more DACs.

I’m just trying to understand the technology and claimed benefit and context.

Updates: so far when Leedh is ON, I can hear a slightly improved image and the bass feels tighter… curious to read what others are hearing.

I am getting a better understanding of this new feature although I am not hearing any differences for now, more A/B testing this weekend :blush:.

Here’s a screenshot with Leedh ON

Here’s another screenshot with Leedh OFF

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I take it this is for users going directly to power amps or actives? Why would you use a digital volume in a high-end system if you have a pre or integrated amp as you will get better results using the amps volume. I get you can then use the remote but your attenuating volume essentially twice are we not? Or am I missing the point.

Page 5 of the 6moons article above:

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All very good questions, thanks for sharing them.

I have one about Roon: is there a way to change the volume on the fly via Roon? I only found Headroom management, but that‘s a permanent setting. AFAIK there is no „slider“ to control the volume by Roon in real time - Roon is always sending that info to the endpoint (eg LUMIN) or DAC. Or did I miss something?

some info on Roon’s DSP volume here: Device volume control which may be relevant

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If you enable Volume Control setting in Lumin app, there should be a volume slider in Roon if you tap the Lumin zone icon (if I remember correctly - cannot check right now) in the bottom right hand corner of the Roon Remote app. Mute should also be there.

Yes, depending on the device setup, its the speaker icon in the lower right.

In some case the slider controls the device volume, can be done over USB connections if the device implements these extensions, plus some other devices (like my Meridian) that has special protocols for this. But it is obviously not part of a standard SPDIF connection.

You can also set up the slider to control Roon’s own, software based “DSP volume”.

Or if neither is enabled, there is no slider.

That’s what I was referring to, since Peter says the Lumin can be set up so that the new Leedh volume is controlled over USB, Roon could do that, or you can switch Roon to do its own DSP volume. In fact, I use a combination in my bedroom: my DAC has a remote control for its volume, but if I don’t want to reach out to get the remote, Roon’s volume is available on the iPad. No audible difference, in this (non-critical) system.

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Anders, Peter, thanks for your answers. I formulated my question badly, so it could be misunderstood. I use the volume in Roon. It triggers the volume algorithm in the LUMIN. My question was if I missed an option to use an on the fly volume control from Roon DSP that could be triggered by the same slider. But this does not exist.
In the end I‘m very fine with the analog volume from the pre anyway :wink:

Don’t you have “DSP volume” available in device controls ? Right-click on device icon / device setup

I don’t think that’s available for RAAT [edit: unless running stock Roon Bridge]. Directly connected / local device and RAAT device have different volume mechanisms in Roon.

All my RAAT devices have DSP volume control

Not on my Lumin

But it’s there on my tablet.

Yeah, like I said, it depends on the device situation.
Roon has to deal with a complicated set of devices and connection modes.
And sometimes those are flawed: a USB device is supposed to declare its capabilities and the streaming gadget it’s connected to is supposed to report it back, but sometimes there are flaws.

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Yep, no DSP volume leveling selectable with Lumin (just Device).

The iPad allows for DSP and Device volume control.

Roon labels all these variants as “DSP Volume” and qualifies as “High Quality” only, probably as it’s not floating (I learn something new here everyday).

In my test I was playing back vinyl that had been ripped at 24/382 with an RME ADI-2 Pro ADC. I first played them in my normal mode (Lumin [A1] - TRL Dude Pre - TRL Samson amps - Green Mountain Audio C-3 HX). Then I re-cabled to remove the TRL Dude Pre. All the cabling was Silent Source. I need to do more testing but my initial reaction was that there was more clarity and detail and also more body to the instuments and more dynamics with no apparent trade-offs so far (other than being limited to one source input.).

You’re not wrong because the integrated volume control in a classical preamp/poweramp or integrated amp configuration, is an integral part of the preamplifier part. When you keep all these preamplifier parts in the chain you keep the possible bottlenecks intacts and the possible virtues of the leedh volume control maybe can’t be heard even if you turn your amplifier volume controle to the max.

So for me the use of leedh volume control goes with a reflection about the signal path in each audio system, to try and decide where are the bottlenecks, maybe if a direct path between dac and power amplifier can be the transparency choice (if dac and power amplifier have a good relationship… impedance, tonal balance, right gain, no need for an other amplification part to add something to listening pleasure but that is damaged by a classical volume control to attenuate this one more amplification part).

For now I use the leedh processing on a U1mini with a Ayon Skylla 2 dac and 813 single end tube power amplifiers with Marten Duke2 speakers in a home office. For me the leedh processing give better results in this configuration than the classical digital volume control of the Lumin, and than the integrated volume control of the Skylla 2 dac. Some years before, I used a Ayon Crossfire integrated amplifier with a motorised ladder volume control and connecting the Skylla2 to the Crossfire by the direct input, bypassing the ladder and using the Skylla volume control, gave far better results in transparency (so take care of the preamplifiers and integrated, the bottleneck is often here behind the pleasure of a colored or limited item). Today the leedh volume control give a bit more relaxed presentation with better tone accuracy, better resolution on fine details, increased naturalness in voices, acoustical instruments that seems less compressed, less planed at one end instead of being gradually attenuated over the entire strip with respect of each levels of dynamics.

Is this a high fidelity volume control at the end? Honestly I don’t know. But all other volume controls are not too, so the deal is always to make a choice between compromise volume controls, and I think the leedh’s one has something special that may give more natural feelings and open windows on the musical work, if the signal path allows it in the audio system.

Next try for me, the U1mini coupled with my Tambaqui dac, luxman M800’s and Egglestonworks Andra’s, with or without my Coincident Statement preamp.

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