DS Dac and Lumin Leedh volume control

Hi @tedsmith,

My Lumin U1 is connected to the DSD Sr via AES.
I tried the Leedh volume, and it sounds slightly better than bit perfect.
I asked Peter Lie, of Lumin why that might be. He was not sure, and mentioned inter sample overs as a speculative answer, but referred me to you to check.
He mentioned that he has heard other Lumin clients say the same thing (Leedh better than bit perfect) with other DACs.
Any idea why with DSD ?

And a second question, please. Would going Lumin (usb) Matrix (aes or i2s) DSD improve on Lumin (aes) DSD ?

Feedback of other Lumin users of course welcome.

Are you saying that using the built in Leedh optional defeat you like using the Leedh enabled or that you prefer using the Leedh to the DS’s volume control?
If you are talking about intersample overs with the DS, they aren’t a problem, the DS keeps all bits of intersample overs (and, further, it applies the volume control after all upsampling.)

I haven’t used or heard a Lumin, so I can’t answer for sure. I’ve heard the Matrix sounding better that previous connections in many systems.

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To clarify:
I control volume with my preamp.
I keep the DS at 100.
I just tried Leedh on the Lumin U1, and prefer it enabled, with volume at 99 or 94 out of 100. A small improvement, not night and day, but definitely higher resolution.

But why would Leedh enabled sound better, if the DS upsamples everything to quad DSD ?

I was wondering the same thing. Thanks for bringing it up. I have the U1 Mini (Leedh volume off) AQ Coffee USB > Matrix SPDIF 2 (Teddy Pardo +9v LPS) > AQ Vodka HDMI > DSD.

I might have been misunderstanding your question. At the bottom I have what I wrote before.

If you are asking why you might like the volume not quite at 100 using the Leedh volume, that’s because something down stream sounds a little better with the volume down just a little. In fact many have discovered that they like the DS’s volume at about 92-94 instead of 100. (With releases before Windom, it was more like around 84 was the best.) So you might want to set the DS volume at, say, 94 and then see what volume you like best on the Lumin.

If indeed you were asking instead about changes in the bitstream caused by using or not using the Leedh volume:

When they disable the Leedh, they are truncating (or, more probably, dithering) the output to, say, 24 bits. The reason I asked is that the phrase “Bit Perfect” shouldn’t be used when talking about volume controls since they by definition deviate from no changes to the bits.

Since they assume that the DAC downstream can’t deal with more than 24 bits (or 32 bits) there is a difference in their box when using the Leedh vs. not. They can’t possibly simulate the DS’s volume because the path to any DAC is too narrow to hold the mathematically correct signal with a volume applied.

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I’m with Ted on the 92 for the DS. Above 92 starts to get a little harsh. I run the DS at 89 to 92 and the Leedh on my U1 mini at 84. This is the sweet spot on my system.

I just got my U1 mini in November and have used Leedh from the beginning. The U1 mini sounded a little harsh without it.

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Thanks Ted.

What I mean is that until now, I used the Lumin without any volume control, so that Roon showed lossless, or bit perfect.
Then I tried activating the Leedh volume control on the Lumin (at 99), and it sounded slightly better: more resolution, better recording location feel, there is more « there », there, to quote the late Art D.

But I don’t understand why ?

Also, why would the DS be better at 94 than 100. At 94, it is closer to the noise floor, and the signal to noise ratio is worse, right ?

The noise floor isn’t as big of a problem as it might seem. The implementation of Huron was more accuracy below 84 than previous releases and more like Redcloud above 84. With Windom I pushed the changeover to 94. With music that isn’t within 6dB if the max there’s no difference, but with very full (e.g. orchestral) or very loud (e.g. compressed pop) music the changeover can matter. Also the sweet spot of components downstream can further confound these issues.
Personally I would expect that using the DS’s volume at < 94 and keeping the Lumin’s at unity would work the best, but it depends on your preamp, etc. exactly where the tradeoffs might be.

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Thanks Ted.

I listen to a lot of classical music and orchestral music.
Do you recommend <94 on the DS or 100 ?

As for why Leedh volume activation improves the sound, which is what @flip49er, other Lumin users and I experienced, it remains a mystery. Leedh seems to be on to something however , because Lumin is not alone. The Swiss firm Soulution also licensed their technology …

If you have a preamp I recomend trying a DS volume of 94, unity volume on the Lumin and using the preamp for volume control.

If you are running the DS directly into your amps I recomend trying the Lumin at unity, and using the DS for your volume control.

If some other combination sounds better to you, by all means enjoy that.

To test the Leedh volume with the DS set the DS to <= 94 and then compare lowering the volume with the Leedh to lowering the volume with the DS.

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Thank you very much Ted for your time, expertise and advice.

I keep the DS Junior at 106, with Leedh usually varying between 88 and 95.

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On the Lumin website it states "Leedh Processing has no effect when Lumin volume set at 100%

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What does “at unity” mean?

I don’t know the Lumin interface. Unity means no changes to the volume. With the DS that’s 100. With my AV Receiver it’s 0. I just don’t know what it is for sure with the Lumin.

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Unity on the Lumin is 100, but as mentioned by @pippen99, the Leedh volume control is deactivated at 100. If you want it on, you have to choose a level <=99.

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Thanks! So, 94 on the DSD, 99 on the U1 Mini and adjust volume on the BHK Pre. Info like this is what makes this forum GREAT!

FYI, Peter Lie of Lumin also suggested 94 on the Lumin, to avoid inter sample overs, but Ted said that is not an issue with the DS.
Strange that 94 volume was suggested both by Ted for the DS and Peter for the Leedh on the Lumin. Probably just a coincidence …

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Lumin in one of their scenarios suggest setting the pre-amp(DSD?) at unity(100) then using the Leedh to adjust volume. I have tried to A/B Leedh in and out but everytime I attempt to turn off or on the track stops. I am using the Lumin App on an Ipad streaming Tidal. What I am I doing wrong?

I compared by going back and forth between volume 99 and 100. At 100, the Leedh automatically disables in my setup, so I don’t have to turn it off, which indeed stops the track.
Hope this helps.

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