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Signal quality of Mono Sub output
#1
Hi all,
I have observed the following: if I connect my subwoofer (B&W DB1) to the Mono subwoofer output of the Devialet it lacks punch and deep bass as if there is an active high pass filter at 20Hz. YOu can even feel thich by touching the membranes, even with loud and extremely deep bass there is no big movement. If I connect the sub to the stereo output ecerything works fine. I even tried to use the mono subwoofer outputs of both my Devialets, one configured for the left and the other for nthe right channel. So I should have a stereo output that is connected to the stereo input of the sub. But same problem, the sub does not make any sense.
And the stereo output of a 400/800 is only available with a AES/EBU cable which you can only build by your own.
This observation was already confirmed by another user, maybe this helps to improve the setups of some users here. I hope Devialet can fix this...
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#2
Hi Vivialet, hmmm interesting. If something's wrong I'd sure like to know about it since I also use a mono sub output of the Devialet to feed my subwooofer (although it passes through an Anti-Mode 2.0 Dual Core first). I do however use and set up my sub only on the Devialet, so never on a different device so I might not have noticed an issue or compensated for it e.g. by setting a higher volume on the sub.

The things I can think of below, I'm sure you've checked all or most of these settings but you'll never know, maybe it helps.

- Did you check if the "subsonic filter" setting under 'General settings' in Devialets configurator is disabled?

Sub out settings on the Devialet:
- filtering set to 'full range'?
- 'tone', 'balance' disabled?
- Volume control set variable?
- Relative level set to?

On the B&W sub:
- did you use the unbalanced mono input?
- are the sensitivity and gain settings for the mono and stereo inputs set identical?

Did you report the issue to Devialet too?

Good luck, and if you don't mind I'd like to know how this "ends"/gets solved. Smile
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
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#3
Hi Antoine,
I can answer all your questions with yes. And it is no level problem. If I increase the level on the sub it starts getting too fat in the upper range but fails in the low regions. Low means below 20 Hz, so more the bass that you only feel. The cut-off on the sub is set to 30 Hz which is the -6db point of my speakers. With the stereo pre-out the sub can shake the house, with the mono out is looses this capability.
And yes, I have reported this to Devialet. Will keep you informed...
Maybe you can try to activate the stereo output of your Devialet, the Anti-Mode supports 2 channels. You should notice an increased low frequency activity. But maybe the gain with your sub is not as big as with my DB1 which goes down to 5 Hz with not too high levels, but you should clearly hear and feel it
The subsonic filter was also one of my list of possible reasons, but it is off by default. Maybe it is automatically activated with the mono out...
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#4
Hi,

I can exactly confirm what Vivialet says.
I use a DSpeaker Antimode (8033sII) and a Linn Melodik subwoofer. Great with Devialet´s stereo preamp-output into the Antimode.
But if I configure a Mono-subout at the Devialet and go mono into the Antimode, the bass loses a lot of pressure. Vivialet describes it very good what happens.
For your information:between the Antimode and the subwoofer is always a Mono cable, that doesn´t matter, apparently.
Perhaps some other subwoofer users can try this out.
Linn LP12 Sondek + Radikal + Urika + Ekos II + EMT HSD006 - roon nucleus + SBooster - Devialet 220 Pro CI - Kef LS50 - Dspeaker Antimode 8033s II + SBooster - Kef KF92 Subwoofer

Bavaria
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#5
Thank you for clarifying this Vivialet, and the confirmation by you Beerman!

When I set it up a long time ago I configured a 15Hz "subsonic filter" on the Anti-Mode because my sub (JL Audio Fathom F112) does -3 dB at 19 Hz and -10 dB at 17 Hz and I figured there isn't much of this low freq. (<20Hz) information available in most music sources anyway. I didn't want to force it out possibly resulting in distortion. Of course I don't mean to suggest in any way this issue you found is to be ignored. In my opinion, it should be fixed. Smile I hate to think there is a problem in the mono output and some of us, maybe including myself, missing deep and forceful bass or pressure at those lowest frequency's.

I hope Devialet will fix it soon!

As I am currently using a single Nordost Heimdall interconnect to the Anti-Mode but of course bought it as a stereo pair it is easy for me to reconfigure the Devialet as a stereo output and use both interconnects to the Anti-Mode. As Beerman says it doesn't matter if the cable from the Anti-Mode to the sub is mono. I'll try to measure the/any difference using REW before and after. Of course my setup is/was completely corrected by the anti-mode and actually measured quite flat to 20Hz (see attachment of the sub output only, black line is after correction) so I might have to redo this all if there is a real difference.

edit: aaaargh, I forgot I deleted my REW install/reinstalled the OS so I have to redo this and remember how it all works again! Big Grin


Attached Files Thumbnail(s)
   
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
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#6
---------------------------------------------------------------------------------------------------
OK. I've just reinstalled REW and made some measurements. I am sorry, but I can't reproduce the issue. Both type of configs measure identical. I've measured from 0-200Hz.

It is strange however that the infoscreens on the Devialet show a 'stereo preout installed' whether I use a mono configured pre-out or a stereo pre-out. If I am not mistaken a mono pre-out was displayed in the past.

I do however notice differences in the dp_cfg.txt configuration files. Differences I would expect. (NB. Be careful: you seem to need to clear the browser cache between the downloads or identical configs are saved!!)

Signal processing
Mono: "MUTE":5, Stereo: "MUTE":7

COAX1:
mono: "TYPE":"INPUT_NOT_AVAILABLE"
stereo: "TYPE":"ANALOG_OUT"

COAX2:
mono: "_dac_mix":"mono"
stereo: "_dac_mix":"right"

Pre-out:
Mono: "usedAsGroup":false
"usage":[{"direction":"output","type":"Sub","defaultName":"Digital 2"}]
Stereo: "usedAsGroup":true
"usage":[{"direction":"output","type":"Preout","defaultName":"Preout"},{"direction":"output","type":"Preout","defaultName":"Preout"}]

Results of the measurements in the picture attached. I haven't taken great care in calibrating the SPL output (battery of SPL meter empty) or mic placement but this does not matter as the goal was to compare. In between measurements nothing changed in the measuring setup. Measurements show the combined output of sub+fronts.

The purple graph is the Anti-Mode in bypass.

The two graphs with red are both made with the infrasonic filter disabled.

The other graphs all with the infrasonic filter enabled and using either a stereo pre-out or mono pre-out.


edit: seeing that the infrasonic filter on the Anti-Mode is not needed/detrimental I'll keep that disabled from now! Big Grin


Attached Files Thumbnail(s)
   
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
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#7
Hi Antoine,
don't believe too strong in measurements. I had too much sound improvements (Devialet firmware, power cables, ...) that did not show any difference in a measurement, but sounded partly much better. And with the subwoofer I can really see the differences I hear by simply watching the membranes. With stereo I have maybe 2cm of linear movement, with mono I have maybe 3mm. The upper bass has the same level from what I can hear. The output level of the Devialet is the same, the volume settings of the sub are the same. Increasing the volume of the sub or Devialet sounds worse, too fat. I will also do some measurements this weekend.
The easiest solution is to use the stereo output. I only need to build a good cable, my test cable was sounding bright and lifeless. Ok, was only a 50 Ohm cable...
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#8
Hi Antoine,

thank you for your measurements. You have found no differences in the frequency range measurements and I expected this. As Vivialet already said, this is no problem of sound level.
Maybe it is a phase problem. I don´t know.
But it is clearly audible in my setup.
So my question is: have you listened to both of the configurations and found a difference by playing music?
Linn LP12 Sondek + Radikal + Urika + Ekos II + EMT HSD006 - roon nucleus + SBooster - Devialet 220 Pro CI - Kef LS50 - Dspeaker Antimode 8033s II + SBooster - Kef KF92 Subwoofer

Bavaria
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#9
Yes, I fully agree with you both that not all -qualitative- changes/improvements can be seen on/read from a graph or even measured in this way. But after reading what you wrote I didn't give it much thought and assumed it to be a -quantitative- change/difference. Again reading now about a difference of 3mm vs. 2cm of movement of the cone(s) should give you an easy to measure difference in SPL (that is at least what my own logic tells me. Smile) Phase measures identically too BTW. I watched my sub's cone move and didn't see noticable differences there as well and REW uses a linear sweep so this is easy to follow. All seemed normal, with the largest cone excursions at the lowest frequencies (remember the sweeps started at "0 Hz")

But no, I didn't listen to compare, in between changing the pre-out settings and actually (more or less coincidentally) ended with the mono pre-out config active and so listened to some music in a way it was before. I did however save both configs so I can easily switch between them. I will listen tomorrow. Could you guys maybe give me an (or some) example(s) of music that shows the issue easily (so that has this low frequency content)?

When did you guys last (re)generate a new config? If it's been recent all is OK, if it's been a while back maybe things have changed in the mean time. Maybe you guys could regenerate a config (clear your browser cache fist please) and compare the new config with the "old" using a website like: https://www.diffchecker.com/ At least the generated on date+time lines should have changed.

If I don't hear any differences I guess I'll have to fabricate a long enough stereo interlink or buy a cheap one to bypass the Anti-Mode. I'm not sure if only connecting both L+R from the Devialet to the Anti-Mode is enough. How do I know the Anti-Mode does anything with L+R in effect converts it to mono? I really don't know and the manual doesn't tell me anything about it. Maybe it just passes the L channel. I don't even know if that is a problem as I thought low frequency content was always mixed in mono (so equally loud in L and R and in phase).
PS Audio P3, Shunyata ΞTRON Alpha Digital and HC/Furutech power cables, Paul Hynes SR7EHD-MR4, DIY Roon Server & Roon Endpoint running AudioLinux Headless, Phasure Lush^2 USB cable, Audioquest Diamond RJ/E ethernet, Uptone Audio etherREGEN, Mutec MC-3+ USB, Shunyata ΞTRON Anaconda Digital XLR AES/EBU, Devialet Expert 250 Pro CI, Nordost Tyr Reference LS cables, Von Schweikert VR-5 SE Anniversary Edition, Anti-Mode Dual Core 2.0, JL Audio Fathom F112. More detail here.

The Netherlands
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#10
for a dual mono setup you have to create complete new config files every time you want to change something. This is due to a limitation of the configurator that is hopefully fixed soon. So yes, the config files are new. And it is not a problem of the dual mono setup, I have observed this earlier with a single unit as well.
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