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TOPIC: DDRC 24 DIRAC Live RoomFeel EQ Target clipping

DDRC 24 DIRAC Live RoomFeel EQ Target clipping 2 weeks 3 days ago #40366

  • plus5volt
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I have notticed that I there is bass distortions when I applied RoomFeel_EQ_Target_Curve.
I have configured DDRC-24 to use 0dB output gain 0dB master volume. I also use 100% volume in my audio source to achieve full 0 dBFs for maximum dynamic range.
The RoomFeel_EQ_Target_Curve has 6.6dB gain at 31Hz. It seem there is not enough headroom for such gain.
I corrected my curves to not exceed 2.5dB gain, but I would like to know, what maximum gain I can use for creating target curves and be sure that there will be no clipping at all.
Maybe devteam could answer to this?
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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 1 week 2 days ago #40754

  • devteam
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@plus5volt

yes, I think that it's a bit of combination here:
a) using digital signal = very little headroom
b) Having a larger boost in lower end with a target curve maybe above the speaker response.
c) having the master volume control at 100% (controlling the input gain).

Have a trial at making your measurement with your master gain not as high within Dirac live. If level is too low, make sure that you UMIK-1 recording level is high enough or just catch up the volume at the amplifier (i.e. increase level there).

This way you don't have to be at 100% and run into potential internal gain structure issues.

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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 1 week 7 hours ago #40795

  • denver8me4dinner
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Draw the shape of target keeping all of it underneath the “all before” response normalized graph, will not clip and will sound great, might have to bump the input of the downstream device by 3 or 6db if like to listen really loudly ,
.02c
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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 6 days 12 hours ago #40811

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This was default RoomFeel EQ target, with slight dip around 3khz. Some songs audibly suffer from bass distortion.


Then I created this, 2.5 db peak. Distortion much reduced. But I notticed that there is sill sometimes.


My current target has peak at 0db.


I am satisfied with the result, but I wonder if there is any headroom I waste with this target, or why default target has 6.6db peak. I would like to be sure I use full available dbFS without clipping.
DDRC-24 has no spdif output, so I am not sure how I can detect clipping during measurements with microphone in REW, I will try during the weekend.

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Last Edit: 6 days 12 hours ago by plus5volt.
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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 3 days 10 hours ago #40928

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I did few more tests, and I can say, that ANY target curve I tested so far causes distortion.
Including my 'Auto target' curve which has peak at 2.5dB, or my 'flat' curves that have peaks at 0db,

I tested it at 24b and 16b 48kHz, both toslink and usb interface of my DDRC-24. Both have identical distortion.
My audio source is windows pc, and I play spotify, player and all system playback volumes set to 100%.

For test I used is randomly found song on Spotify "Losing (Remix) by Vintage Culture, Kalozy, JORD",
beat sound that is at around 0:43s is ugly distorted.
I checked FFT of this song, it has no deep bass line, it does not go below 45Hz at this distorted moments.
Spotify app has normalisation disabled and high quality enabled.

This is not speakers or amplifier issue. Because when I set 90% (-1,5dB) on my audio source master volume on PC,
then distortion dissapears, and I can set my amplifier volume level as loud as I want, and even very loud playback has no distortion.

Something is wrong with the signal processing. Can anybody try to reproduce this as well?
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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 3 days 9 hours ago #40936

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I did even more experiments and found out that I just need correct output volume level at the DDRC to -1.5-2dB, and I suppose it is done after dirac correction.
When I use dirac target curve with higher peak, then I have to set lower output volume to get rid of distortion.
After this experiments, I started to think if this is maybe clipping analog end or D/A section of the DDRC-24 unit, unfortunatelly i have no scope to verify this.
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DDRC 24 DIRAC Live RoomFeel EQ Target clipping 2 days 22 hours ago #40949

  • Tony_J
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This is an issue that I raised in here a while back - the fundamental problem is that the user gets zero feedback from the calibration tools as to what level of boost is applied by the Dirac filters. If you are running the master volume at 0dB, you essentially have no headroom to play with - by the time the (internal) signal reaches the DAC, you had better have attenuated it to the point where there are no peaks in the signal that exceed 0dB. Not an easy thing to do if the only thing you have to go on is the rather idealized/smoothed before & after curves that are shown in the calibration tool. It would be entirely possible for the calibration tool to report what the max boost is in a given set of filters; equally, it would be entirely possible for the miniDSP hardware to report a "clipping" condition. So far, neither Dirac nor miniDSP seem to have any answer to this other than "trial and error", which I find disappointing.
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