Rooms at the show using DSP

[acg]

42 minutes ago, POV said:

That doesn’t alter the fact that your representation of the objective of DSP and the relative differences between room treatment and DSP was objectively incorrect.

 

Objective of DSP?  There is no objective of DSP...you just made this up.  People have objectives and use the appropriate technologies accordingly.

 

Some of the objectives achieved with use of room treatments are to reduce modal behaviour, provide a diffuse sound field, control reverberation.  DSP, as commonly used in a stereo setup cannot reduce all modal behaviour at all positions within the room like room treatments can.  Neither can DSP diffuse the sound field...that is achieved with room treatments, and apart from some of the newer technology (Dirac Live) reverberation times are generally not controlled by DSP, but Dirac Live relies on more than a stereo setup. 

 

DSP is great for correcting SPL at specific positions within the room which is a huge thing but it does not fix many of the other room/system problems necessary for great stereo sound.  In my experience, if DSP is used judiciously in a poorly or moderately treated listening space then you may as well give up on any analogue sources unless you also run them through the room correction filters, because the turntable/r2r will sound inadequate by comparison.  That is the sort of effect that getting the frequency response correct at the listening position makes which is a thing that can be achieved more readily using DSP.  The other things that are important to sound quality, some of which I mentioned above, are not helped by DSP and can only be done using some forms of room treatments.

[Guest]

I suspect that people who do not like DSP have a carefully selected dedicated room, treated with bass traps and catered for first, second and even third reflection points.

 

The rest of us, with less perfect rooms, will do some treatment and use DSP as required. 

 

For me, I continue to enjoy my band aid setup of DSPed Kii Three's, which I hope will reappear in next year's show with the Seven's... 

[POV]

I have a custom designed room with huge investment in bass traps, absorption, and diffusion.  I use DSP extensively and it’s synergistic.  It’s really interesting experimenting with Dirac Live and comparing to RoomPerfect.  Both amazing products with different strengths and weaknesses but both dramatically improve overall sound quality and musical enjoyment even in my optimised environment.

Edited October 26, 2023 by POV

[Stereophilus]

4 hours ago, frednork said:

interesting comments,  so how do people feel about dsp being used at the show ? is it a smart thing to do, or is it "cheating", or changing the natural character of the speakers or other things?

I guess to cut a little deeper, the question needs to be asked of the listener visiting the room... because if they are auditioning speakers with a view to purchasing, unaware of DSP being applied and unable/unwilling to use DSP themselves, this could pose a problem for them.  Within this example context it could certainly be viewed as cheating if the potential customer is uninformed.

 

On the other hand, if the listener is visiting the room purely for the enjoyment of listening to music at a hifi show, then DSP done well is just enhancing their experience, whether the listener realises it or not.  I wouldn't view DSP as "cheating" in this context, because the listening intent is different.

[Guest]

19 minutes ago, POV said:

I have a custom designed room with huge investment in bass traps, absorption, and diffusion.  I use DSP extensively and it’s synergistic.  It’s really interesting experimenting with Dirac Live and comparing to RoomPerfect.  Both amazing products with different strengths and weaknesses but both dramatically improve overall sound quality and musical enjoyment even in my optimised environment.

 

I'm with you. A dedicated and purpose built room, MSR Spring (bass) traps, acoustic panels, and I did away with a non-DSP high-end pre for a Dirac-enabled multichannel pre even for 2-channel purposes.

 

DSP is another tool that can be used to improve sound reproduction. We'd be crazy not to embrace it IMO.

[davewantsmoore]

Calibrating the speaker well in a room, is just what you do to set up a good playback system.

 

This could be any or all of the following:

• Choice of speaker(s)
• Positioning of speaker (and listener) in the room
• EQ
• Acoustic devices ("room treatment")

 

Failing to use any of these where they are warranted, is just "poor system design".... and people should probably expect them all in any decently performing system.

[Satanica]

I think for this conversation to make any real sense, posters should refer to what frequency range they are discussing in relation to DSP.

Just frequencies under the Schroeder frequency of a room (100-200Hz)?

 

Transition zone?

Full frequency?
 

Edited October 26, 2023 by Satanica

[Keith_W]

I think they are talking about the modal zone, i.e. below the Schroder frequency. 

 

Just for context, people should remember that most "anechoic" chambers are not anechoic below 50Hz. The reason why is because the thickness of absorbers required is excessive. A 50Hz sine wave has a wavelength of 7m. To attenuate this, you need a foam thickness of 1/4 wavelength, but if you put it against the wall it halves (because the sound travels through the thickness of the foam twice), but we are still talking about almost one meter of foam on every surface. I am guessing that NOBODY on SNA has a properly bass trapped room even if they think they have bass treatments in place. At best the bass is partially treated, and even then only down to a certain wavelength. In the meantime, the same bass treatment works wonders for upper frequencies, so the end result is a spectral imbalance, where upper frequencies are massively attenuated, whilst bass frequencies are relatively untouched. 

 

I am of the opinion that the best way to treat bass frequencies is with DSP. I have mentioned in my system thread that I am using a Virtual Bass Array (VBA). The idea of a VBA is to cancel bass reflections and turn your room from a "room" to a long tube as far as long wavelengths are concerned. I have given the calculations required in my system showcase thread. My own experiments with a VBA have been a partial success, and it completely evens out the bass at the listening position, and has some effect off axis but not as dramatic as I had hoped. People who have been to my house have heard the effect of the VBA, although to be fair I have not demonstrated it on/off for them to compare. 

 

Also, room treatment does nothing for timing issues so some form of DSP is required anyway if you own subs. While you are at it, you may as well correct the frequency response. 

[Satanica]

12 minutes ago, Keith_W said:

I think they are talking about the modal zone, i.e. below the Schroder frequency.

Well, I haven't read anything to make me think just that. I think many posts here have not been on the same page in this regard.

[POV]

14 hours ago, Satanica said:

Well, I haven't read anything to make me think just that. I think many posts here have not been on the same page in this regard.

Agreed and that’s kind of the point I was making at the start of this.  A very narrow view of the value of DSP was shared I was suggesting that I don’t believe it was an accurate portrayal.  If coming from a point of view of only applying DSP to  bass and sub bass frequencies then you will see things differently to viewing it from point of view very differently to those utilising it for a broader spectrum of the audible range

 

For my part, both via Dirac Live and RoomPerfect I have experimented and am using it across a far broader frequency range than just the modal zone.

 

But I am trying not to engage in arguments as part of the refresh of the site guidelines!

Edited October 26, 2023 by POV

[acg]

1 hour ago, davewantsmoore said:

Calibrating the speaker well in a room, is just what you do to set up a good playback system.

 

This could be any or all of the following:

• Choice of speaker(s)
• Positioning of speaker (and listener) in the room
• EQ
• Acoustic devices ("room treatment")

 

Failing to use any of these where they are warranted, is just "poor system design".... and people should probably expect them all in any decently performing system.

 

This sums it up entirely as far as I am concerned.

 

 

32 minutes ago, Keith_W said:

I am guessing that NOBODY on SNA has a properly bass trapped room even if they think they have bass treatments in place. At best the bass is partially treated, and even then only down to a certain wavelength. In the meantime, the same bass treatment works wonders for upper frequencies, so the end result is a spectral imbalance, where upper frequencies are massively attenuated, whilst bass frequencies are relatively untouched. 

 

Doesn't have to be this way.  My room probably has as much bass treatment as any going around, perhaps more than a lot of studios.  The way it has been done is effective sub 600Hz and in particular below 200Hz with huge SPL/decay changes even at 20Hz but is virtually unchanged to the pre-treated room above that.  This kind of treatment does not fix all bass issues but it does certainly change the sound.  

 

 

1 hour ago, Marc said:

DSP is another tool that can be used to improve sound reproduction. We'd be crazy not to embrace it IMO.

 

Yep.  A point I made earlier is that unless our analogue sources are digitised somewhere along the playback chain that our digital sources are probably going to sound better due to the improved frequency response via DSP.

 

 

17 minutes ago, POV said:

A very narrow view of the value of DSP was shared I was suggesting that I don’t believe it was an accurate portrayal.  

 

You are still misunderstanding what I actually said.  I did not say "DSP bad...room treatment good", I effectively said that DSP does not actually solve small room problems, it just shifts things about so they are less bad.  Same with room treatment, but it also fixes several things not possible with DSP.

[Satanica]

15 minutes ago, acg said:

Same with room treatment, but it also fixes several things not possible with DSP.

Sure, and DSP can solve things that room treatment cannot such as:

 

1) Reducing measured frequencies less than about 50-60Hz which are practically impossible for that vast majority if not all listening environments.

2) Having multiple target curves easily switchable.

[davewantsmoore]

1 hour ago, Keith_W said:

I am guessing that NOBODY on SNA has a properly bass trapped room even if they think they have bass treatments in place. At best the bass is partially treated, and even then only down to a certain wavelength. In the meantime, the same bass treatment works wonders for upper frequencies, so the end result is a spectral imbalance, where upper frequencies are massively attenuated, whilst bass frequencies are relatively untouched. 

Yes, I guess it depends on your definition of "properly" bass trapping.

The room has sparse modal behaviour at LF.  Suppressing this means turning the room more and more into an "anechoic chamber" .... which is difficult to do, and difficult to do just at low frequencies.

 

1 hour ago, Keith_W said:

I am of the opinion that the best way to treat bass frequencies is with DSP.

Most effective action to "treat" bass frequencies in a small room, is by using lots of bass sources.    This then increases the number/frequencies of the modes which are excited.    It solves the problem at its source.... ie. prevents the problem of "lack of modes excited".

Of course, they can all be used together though.

 

If you were ever designing an "all out" room or system, then subwoofers spaced randomly through the horizontal and vertical plane is a very very good thing.    I will do something like this, one day, if I ever build a house.

 

1 hour ago, Keith_W said:

Also, room treatment does nothing for timing issues

I'm not 100% sure what you mean by this.

If you mean lack of "time alignment" between the sub and mains .... then this isn't an issue unless they are really! spaced apart, or there is weird, unmatching crossovers employed.

[Keith_W]

1 hour ago, acg said:

My room probably has as much bass treatment as any going around, perhaps more than a lot of studios.  The way it has been done is effective sub 600Hz and in particular below 200Hz with huge SPL/decay changes even at 20Hz but is virtually unchanged to the pre-treated room above that.  This kind of treatment does not fix all bass issues but it does certainly change the sound.  

 

20Hz wavelength = 17.15m. We are talking about a foam thickness of 2.15m required to attenuate 20Hz. How thick is your foam? 

 

(edit) I just remembered that in small room acoustics, 20Hz is probably in the pressure zone. 

Edited October 26, 2023 by Keith_W

[davewantsmoore]

2 hours ago, Keith_W said:

I think they are talking about the modal zone, i.e. below the Schroder frequency. 

Yes.  I was responding to comments which seemed to be about low frequencies (bass traps, etc.).

[davewantsmoore]

1 hour ago, POV said:

But I am trying not to engage in arguments as part of the refresh of the site guidelines!

From memory, the rules about this was to be constructive.

[davewantsmoore]

5 minutes ago, Keith_W said:

How thick is your foam? 

That's a velocity based device (like a "porous absorber").

 

Pressure based devices, like some sort of "moving membrane or panel"  don't need to be deep.

[tripitaka]

9 minutes ago, Keith_W said:

 

20Hz wavelength = 17.15m. We are talking about a foam thickness of 2.15m required to attenuate 20Hz. How thick is your foam? 

 

Don't worry, @acg has gone 'nuts' with attenuation, I'm amazed his family let him get away with but I would like to hear his system one day!!

[tripitaka]

12 minutes ago, davewantsmoore said:

 

If you were ever designing an "all out" room or system, then subwoofers spaced randomly through the horizontal and vertical plane is a very very good thing.    I will do something like this, one day, if I ever build a house.

Ha! My wife reckons this is what I will do when I finally go completely mad, she envisions woofers hanging in the air like chandeliers.

[playdough]

2 hours ago, Keith_W said:

I am guessing that NOBODY on SNA has a properly bass trapped room even if they think they have bass treatments in place.

Interesting comment, 

It doesn;t cover traps like large multiple  Mass Loaded Vinyl, air loaded traps or velocity pressure panel  Traps 

 

Normally these things are hard to buy, they have to be made. 

 

Once you have used them it's hard to listen to a Lounge without them,

Generally a user is aware of unbalancing a treatment regime as they become proficient in the aspect of Acoustic control. Design,  Construction, Application and Measurement, to their listening pleasure.

 

THere is way more to Acoustic control other than "foam thickness" and Porous absorbers.

 

 

Edited October 26, 2023 by playdough

[acg]

42 minutes ago, Keith_W said:

 

20Hz wavelength = 17.15m. We are talking about a foam thickness of 2.15m required to attenuate 20Hz. How thick is your foam? 

 

(edit) I just remembered that in small room acoustics, 20Hz is probably in the pressure zone. 

 

Very little foam in use Keith.  I built a bunch of panel resonators.  Their effectiveness at 20Hz is increased when the door is closed (a sealed, largely soundproof room) and is a pain because they eat almost all of the room gain of my subs.

[playdough]

12 minutes ago, acg said:

they eat almost all of the room gain of my subs

If you had more than 10 watts or tune a huge horn or reflex  enclosure you might go better 

EDIT, my goal was to get rid of room gain  

Edited October 26, 2023 by playdough

[RoHo]

A point that was brought up earlier but not really expanded on- how effective can the typical domestic DSP be in this very specialised situation where a large percentage of the room is “listening position”?  Do you set the LP to be the middle few seats?

[POV]

7 hours ago, acg said:

You are still misunderstanding what I actually said.  I did not say "DSP bad...room treatment good", I effectively said that DSP does not actually solve small room problems

Nah, I didn’t misunderstand.  I didn’t think that you were saying that.  I’m not sure who you are trying to convince, but I don’t think anyone that understands the subject matter thinks for a second that DSP actually solves room problems.  Not sure what you mean by small rooms, but DIRAC Live and RoomPerfect are both really effective in large and small rooms, just in different ways.

 

7 hours ago, acg said:

it just shifts things about so they are less bad.  Same with room treatment, but it also fixes several things not possible with DSP.

This is where you are not understanding fully, modern DSP room correction is not just ‘shifting things about’ this is a vast oversimplification of what is happening in the frequency domain and unrelated to what is happening in the time domain.

 

Room treatment and DSP shouldn’t be seen as in some kind of competition, but rather for best effect should be used together synergistically.  It’s also true that DSP can assist with a number of things not  possible with passive room treatment.

 

Honestly I suggest do some experimenting with DIRAC Live, and you will see for yourself.

[sdotmouse]

Are you saying that DSP can operate in the frequency domain without affecting the time domain? 

 

s.m