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Sweet Room
#31
(17-Oct-2020, 21:12)David A Wrote:
(17-Oct-2020, 15:05)Jean-Marie Wrote: Since the Devialet does all its signal processing using floating point, digital clipping is not the real issue.

However boosts shall be handled with really extreme precautions because you will rapidly hit the maximum power of your amplifier and then trigger soft clipping.

With a boost of 20dB like mentioned by @PeppaPig , it would mean that if you are listening with the volume above -20dB you could enter in soft clipping.

So the safer approach is the one recommended by @ogs to only reduce and avoid boosting.
That means that instead of flattening the curve around the middle you flatten it around the bottom.
You will need to listen with the volume knob turned higher, but that will be much safer.

Jean-Marie

I agree with the above but there is another reason to avoid trying to correct for dips in the room response in the bass frequencies.

Dips in the room response at bass frequencies occur in locations which are a null for a room mode ("standing wave"). It doesn't matter how much  EQ you apply to the signal at that frequency, there will always be a null in the room response at that position of the room. It's effectively impossible to fill a null because it's caused by the sound waves cancelling each other at that location in the room. If you have a problem null in your room response at the listening position, the only ways to effectively deal with it are to move the speaker positions and/or the listening position, or to physically deal with the room mode. You can eliminate peaks in the response with cuts in EQ at those frequencies but you cannot eliminate dips in the response which result from room modes.

While the nulls will always be found in the same positions in a room, moving the speaker positions can change how strongly the speakers activate load the room mode so if you can move the speakers to a location where they do not activate the mode as strongly, then the dip in the bass at the null points in the room will not be as severe. If you move the listening position to an area outside the location of a null point, the reduction in level at that frequency will also not be as severe.

The alternative is physical treatments in the form of bass traps.

Correction techniques such as Sweet Room are often called "room correction" but  they do not actually correct the room, in fact they do not change the room or its behaviour in any way. What they do is to compensate for the behaviour of the room by applying an opposite alteration to the musical signal so if you have a peak in the bass they apply a cut and if you have a dip in the bass they correct with a boost. In my view what they do should be called "room compensation" rather than "room correction". On the other hand physical room treatments actually do change the room response, they effectively become a part of the room and the changes they make in the room response can actually smooth out the peaks and dips in the room response at bass frequencies as well as doing other things. Physical treatments actually can correct the room. That doesn't mean that physical corrections are automatically better than electronic corrections, they have different capabilities and strengths. Dips in the room's response at bass frequencies is one problem where physical solutions (moving the speakers and/or listening position, or using bass traps) are better than electronic corrections. On the other hand, if you have a dip in the response at bass frequencies which is due to the speaker rather than the room, physical corrections won't help but electronic correction can help. You need to pick the right solution for the problem and there is no one single approach, whether that be electronic correction or physical correction. that can solve every problem.

+1
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#32
(18-Oct-2020, 13:06)ThomasD Wrote: I am very satisfied with Sweet room. Maybe the manual is not so custom friendly but it works!
For measurement I used: 
XTZ Room Analyzer II/II Pro
I only corrected for room resonances below 250 HZ. Found 3 resonaces in each channel which are corrected. Now I have a a straight (+- 2.5 dB) respons from 31 to 20 000 Hz. Very impressive result for such a small speaker as the Dynaudio C1/II. I have tried SAM but did not like the result. Impressive first but not in the long run.
I attach my  eq.txt file.


Hi Thomas,

Are those EQ 1 to 9 has to be in order?

Like for low Hz to higher Hz?
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#33
(18-Oct-2020, 23:39)PeppaPig Wrote:
(18-Oct-2020, 13:06)ThomasD Wrote: I am very satisfied with Sweet room. Maybe the manual is not so custom friendly but it works!
For measurement I used: 
XTZ Room Analyzer II/II Pro
I only corrected for room resonances below 250 HZ. Found 3 resonaces in each channel which are corrected. Now I have a a straight (+- 2.5 dB) respons from 31 to 20 000 Hz. Very impressive result for such a small speaker as the Dynaudio C1/II. I have tried SAM but did not like the result. Impressive first but not in the long run.
I attach my  eq.txt file.


Hi Thomas,

Are those EQ 1 to 9 has to be in order?

Like for low Hz to higher Hz?

Not according to my findings.  But I recommend not to compensate too much and focus on the lowest room resonance.. Less is best.
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#34
(18-Oct-2020, 13:06)ThomasD Wrote: I have tried SAM but did not like the result. Impressive first but not in the long run.

Hi, that is rather strange. I know many say they do not like SAM very much, but with Sweet Room SAM could really do wonders. This would be very similar to what I did: SAM on at 92%  - measurement with AudiolenseXO (not 100% SAM as this would trigger excursion limitation on the sweep). Audiolense would fix the ugly peaks in the bass region and it would all sound fabulous.
My theory is that SAM would make any resonances/standing waves in the room even worse. When corrected with Audiolense I really got to hear what SAM could do. I'm not saying your Dynaudios will benefit in the same way, but it might be worth a new try now that Sweet Room is here.

EDIT: I don't see the C1 ll in the list, only C1 and C1 Signature. Are you sure you are using the correct SAM profile?
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#35
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#36
Do we then set SAM at 0% while doing the Sweet Room configuration?
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#37
SAM is part of how your speakers interact with the room and this is what you want to correct.
If you normally use SAM you should keep it in it's usual setting for both measurement and configuration of Sweet Room, providing that you use it for room related resonances in the bass region. As always with changes a bit of experimentation will probably be necessary.
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#38
(21-Oct-2020, 06:30)tategoi Wrote: Do we then set SAM at 0% while doing the Sweet Room configuration?

(21-Oct-2020, 08:24)ogs Wrote: SAM is part of how your speakers interact with the room and this is what you want to correct.
If you normally use SAM you should keep it in it's usual setting for both measurement and configuration of Sweet Room, providing that you use it for room related resonances in the bass region. As always with changes a bit of experimentation will probably be necessary.

Ogs is right that SAM is part of how your speakers interact with the room so you should keep it at your normal setting for calibration and when listening BUT if you then change the SAM setting, you're changing how the speaker loads the room at low frequencies and that may exacerbate some room modes to a greater extent if you increase the setting or reduce the level of modal behaviour if you reduce the setting. That means that you should probably remeasure and create a new Sweet Room config if you change your SAM setting. I wouldn't think a small change in the setting would really need a new configuration but if you change your SAM setting enough to find that you're not as happy with SAM as you were previously then I think you would need to remeasure and create a new configuration.

If you make big changes in the room such as new furniture which is more or less absorbent than the previous furniture, move the speakers and/or listening position, change your speakers, or add or remove physical acoustic treatments you should also remeasure and create a new Sweet Room configuration.

This is not a do it once and it's right forever thing. You're compensating for the acoustic behaviour of your room as it is when you take your measurements. If you make any change to something which affects the acoustic behaviour of your room, then the Sweet Room configuration you're using may be no longer ideal for your room's changed acoustic behaviour.
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#39
(17-Oct-2020, 21:12)David A Wrote:
(17-Oct-2020, 15:05)Jean-Marie Wrote: Since the Devialet does all its signal processing using floating point, digital clipping is not the real issue.

However boosts shall be handled with really extreme precautions because you will rapidly hit the maximum power of your amplifier and then trigger soft clipping.

With a boost of 20dB like mentioned by @PeppaPig , it would mean that if you are listening with the volume above -20dB you could enter in soft clipping.

So the safer approach is the one recommended by @ogs to only reduce and avoid boosting.
That means that instead of flattening the curve around the middle you flatten it around the bottom.
You will need to listen with the volume knob turned higher, but that will be much safer.

Jean-Marie

I agree with the above but there is another reason to avoid trying to correct for dips in the room response in the bass frequencies.

Dips in the room response at bass frequencies occur in locations which are a null for a room mode ("standing wave"). It doesn't matter how much  EQ you apply to the signal at that frequency, there will always be a null in the room response at that position of the room. It's effectively impossible to fill a null because it's caused by the sound waves cancelling each other at that location in the room. If you have a problem null in your room response at the listening position, the only ways to effectively deal with it are to move the speaker positions and/or the listening position, or to physically deal with the room mode. You can eliminate peaks in the response with cuts in EQ at those frequencies but you cannot eliminate dips in the response which result from room modes.

While the nulls will always be found in the same positions in a room, moving the speaker positions can change how strongly the speakers activate load the room mode so if you can move the speakers to a location where they do not activate the mode as strongly, then the dip in the bass at the null points in the room will not be as severe. If you move the listening position to an area outside the location of a null point, the reduction in level at that frequency will also not be as severe.

The alternative is physical treatments in the form of bass traps.

Correction techniques such as Sweet Room are often called "room correction" but  they do not actually correct the room, in fact they do not change the room or its behaviour in any way. What they do is to compensate for the behaviour of the room by applying an opposite alteration to the musical signal so if you have a peak in the bass they apply a cut and if you have a dip in the bass they correct with a boost. In my view what they do should be called "room compensation" rather than "room correction". On the other hand physical room treatments actually do change the room response, they effectively become a part of the room and the changes they make in the room response can actually smooth out the peaks and dips in the room response at bass frequencies as well as doing other things. Physical treatments actually can correct the room. That doesn't mean that physical corrections are automatically better than electronic corrections, they have different capabilities and strengths. Dips in the room's response at bass frequencies is one problem where physical solutions (moving the speakers and/or listening position, or using bass traps) are better than electronic corrections. On the other hand, if you have a dip in the response at bass frequencies which is due to the speaker rather than the room, physical corrections won't help but electronic correction can help. You need to pick the right solution for the problem and there is no one single approach, whether that be electronic correction or physical correction. that can solve every problem.

I completely agree with your description. 
As room modes have a spacial character determined by room shape/size and frequency but independent from the loudspeaker output. One issue is that if there is a dip or null in the frequency response  and one tries to compensate by increasing the acoustical output of the speakers requires the driver (woofer, as it is mostly low frequency where room modes matter) to increase amplitude to much higher levels at that selected frequency. Increasing the output of speakers increases the level of distortion not only at that frequency (thermal and intermodulation). Of course having too high excursions can damage that driver physically. That was one of the benefits of SAM that it limited the speaker correction (model i.e. woofer specific) to avoid excessive distortions and damage.
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#40
(19-Oct-2020, 21:13)ogs Wrote:
(18-Oct-2020, 13:06)ThomasD Wrote: I have tried SAM but did not like the result. Impressive first but not in the long run.

Hi, that is rather strange. I know many say they do not like SAM very much, but with Sweet Room SAM could really do wonders. This would be very similar to what I did: SAM on at 92%  - measurement with AudiolenseXO (not 100% SAM as this would trigger excursion limitation on the sweep). Audiolense would fix the ugly peaks in the bass region and it would all sound fabulous.
My theory is that SAM would make any resonances/standing waves in the room even worse. When corrected with Audiolense I really got to hear what SAM could do. I'm not saying your Dynaudios will benefit in the same way, but it might be worth a new try now that Sweet Room is here.

EDIT: I don't see the C1 ll in the list, only C1 and C1 Signature. Are you sure you are using the correct SAM profile?
Thanks for interesting comment. I use C1 signature which should be same as C1/II but maybe Signature profile is not optimal? I assume Dynaudio knew what they did when designing the C1. The profile tries to extend frequency range in the bass but my feeling is this has a negative impact on overall sound. The frequency range without SAM is within +-2.5% down to 30 -20000Hz.  This is enough for me and believe you can not ask for more from such a small speaker, or?
Expert Pro 220. Dynaudio C1 II. Rega P8. Lyra Delos. Primare BD 32. 
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