IK Multimedia ARC System vs Acoustic Treatment???
Old 17th December 2012
  #391
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DanDan's Avatar
Levels

Here's an interesting if puzzling insight into Lights' ARC testing.
Left Speaker (the bad one). Note how a dip without ARC has been replaced by a resonance. But it isn't really sticking out much. I guess I would chose the have the Bass rather than the Null.
Note also the Y axis on the graph. I have asked if this was a 24 Bit recording but haven't heard back yet.
Perhaps it's something to do with ARC being in circuit.


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Note the non linear looking decay.

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DD
Old 17th December 2012
  #392
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Lights's Avatar
I have to say DanDan, I have no idea what bit depth REW uses. It goes through the standard Windows audio pipeline and through my ProFire 2626. I used a 3rd party audio router DDMF AudioStream to hook in ARC2 during the measurement.

I should also add that under the left speaker, which sits on my desk (with as much acoustic decoupling as I can muster--mopads and sorbothane feet) is a cabinet (built into the desk) with my DAW PC in it. The cabinet is vented with a 120mm PC fan which is screwed into the back of the cabinet. During the sine sweep (and ONLY during the sine sweep or I would correct it) the fan rattles badly at one very low frequency... it very well could be right around 40Hz that it rattles. I was hoping that the REW recording would be immune to this rattle, but it's entirely possible that's what I'm getting down there if you say it's not a regular decay.
Old 17th December 2012
  #393
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DanDan's Avatar
Odd

Thanks Lights. The odd thing here is the very low levels on your Y scale.
Despite this your ETC shows a very well achieve 70dB between peak and background noise. You could clear up the fan issue easily. Use the Sig Gen. Tick the Frequency follows Cursor box. Sine Wave. Slide the cursor over the LF ridges, the Sine will generate that exact frequency. If there is a resonance triggering the fan rattle you will easily find it.

The non linear slope, particularly on the newly introduced ARC resonance will give false ideas about it's length. The original calculation was over the very flat first 17dB or so. The slope accelerates greatly after that. REW itself suggest about 525mS. I am sure you would have noticed 900!
I believe Jens central point was to be careful in extracting Decay information casually from graphs. Or beware of the unseen. A point well made and well accepted I hope. In the past I simply assumed that EDT, often the first stat presented, was the best choice. It so isn't.
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DD
Old 17th December 2012
  #394
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Jens Eklund's Avatar
Quote:
Originally Posted by DanDan View Post
I believe Jens central point was to be careful in extracting Decay information casually from graphs.


Especially graphs showing only a 17 (or so) dB range.


OP: Care to share those IR files?
Old 17th December 2012
  #395
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Lights's Avatar
I can send you what I sent to Dan. PM me your email address.
Old 17th December 2012
  #396
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DanDan's Avatar
Sharing

Lights, if you Zip the .mdat file you can post it directly here for all to play with.
I would like to point out again we are focussed on the worst measurement here, the others show great improvement. In the current measure, the bad one, I am curious as to why ARC has not shortened the LF boom. These Very Low Frequency issues. where treatment has failed or is not enough, are THE place where DRC can really shine. I have had and have seen great success in this regard. I have intended to present some results but people may know which product I am Beta Testing so I don't really want to Shill.
The very low levels on the SPL graph mystify me, there is probably an offset or something going on with ARC and the other intermediaries. However, the data, being a Before and After, and showing a healthy S/N Ratio, looks sound to me.

DD
Old 17th December 2012
  #397
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Lights's Avatar
I sent the zip file to Jens for now.

I think that the "DDMF Audiostream" plugin host may have something to do with the weirdness, but I can't be sure. The REW measurement was certainly cobbled together.

I am still wondering about that fan rattle.
Old 17th December 2012
  #398
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Jens Eklund's Avatar
Thanks Lights, now we can see better what´s going on:

IK Multimedia ARC System vs Acoustic Treatment???-left-without-arc2.gifIK Multimedia ARC System vs Acoustic Treatment???-left-arc2.gifIK Multimedia ARC System vs Acoustic Treatment???-left-arc2-800ms.gif



As you can see; there´s an increased decay time at 40 Hz using the ARC2 (and it´s not fan rattling you see in the measurements). Please note that I´m not saying that the overall situation is better without the ARC2, I´m just trying to show that these systems cannot replace proper acoustic treatment (and I´m not suggesting that you believe so, but there are many out there who do). It might be a last option once treatment is competed or the last resort if no treatment can be added to the room for various reasons.


If you make new measurements; don´t limit the frequency range to 400 Hz. Make it 20 (or even 10) Hz to 20 kHz sweeps (and use 512k sweep length). You can improve your S/N-ratio by doing multiple sweeps (averaging). Also; play the speaker fairly loud. Just below to the point they start to change character or distort audibly.
Old 17th December 2012
  #399
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I kinda doubt that a small fan rattle could generate much volume at 35Hz. A rattle sound is probably dominated by frequencies higher than that. Once you get down to even 100Hz, it takes a fairly large surface area x displacement to generate low frequencies.
Old 17th December 2012
  #400
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The thing is that I do believe that I've exhausted my acoustic treatment options. The room is jammed with treatment right now and experimenting with more produced no noticeable improvements. I think this is where I hit steady-state for now until I buy a new home, which I don't anticipate soon.
Old 17th December 2012
  #401
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Your result (what can be seen, since the IR is limited to 400 Hz) is not bad. We normally accept longer decay times below about 50 Hz since they are sometime hard to deal with. Unless you actually hear it and is annoyed with it; be happy and start making music.
Old 17th December 2012
  #402
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I agree just from my perception of the improvement. I feel like I can accurately mix and master my own music and listen much more accurately to reference tracks. I don't believe that the resonance that low comes into play much in my real world mixing and critical listening.

I spent months getting to the 'before arc' graphs and still was unhappy. I spent a day getting to the 'after arc' state and I'm happy. I see the low resonance in the left speaker but I don't hear it in real world use.
Old 17th December 2012
  #403
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Jens Eklund's Avatar
If you hadn’t treated your room before adding the ARC, you probably wouldn’t be as excited about it.
Old 17th December 2012
  #404
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Lights's Avatar
Agreed.
Old 3rd January 2013
  #405
Gear interested
works for me

If anybody gets this far in all these posts -

I just installed ARC 2 and it just works. Easy as hell to use, flexible, sounds just terrific. This is a true feat of software engineering - I will use this for my audiophile listening as well as monitoring.

I had to tear off my wall treatments for aesthetic reasons (my wife hated it) and so got ARC 2 to clean up the sound. In short - the untreated room with ARC 2 is far better-sounding than the treated room was. Your mileage may vary, but for me, this is the best piece of software since Ableton Live.
Old 4th January 2013
  #406
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Jens Eklund's Avatar
Quote:
Originally Posted by ferrellms View Post
If anybody gets this far in all these posts -

I just installed ARC 2 and it just works. Easy as hell to use, flexible, sounds just terrific. This is a true feat of software engineering - I will use this for my audiophile listening as well as monitoring.

I had to tear off my wall treatments for aesthetic reasons (my wife hated it) and so got ARC 2 to clean up the sound. In short - the untreated room with ARC 2 is far better-sounding than the treated room was. Your mileage may vary, but for me, this is the best piece of software since Ableton Live.
Well, I guess it depends on how well the room was treated. If similar to this:http://www.americanmusical.com/image.../aurwg_3br.jpg; I´m not surprised if it sounds better without the “treatment” and using DRC instead …

I´ll repeat what’s been said before; DRC will never replace acoustic treatment (at least not if assumed well done) simply because you cannot fix all issues with it (early reflections, decay times etc.). The only option is to treat, but this does not mean that room correction (manual especially) is in vain: It can help to further enhance the room response in a well treated room or help to make a terrible room “manageable” if treatment is not an option.
Old 7th January 2013
  #407
bwo
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Quote:
Originally Posted by Jens Eklund View Post
Well, I guess it depends on how well the room was treated. If similar to this:http://www.americanmusical.com/image.../aurwg_3br.jpg; I´m not surprised if it sounds better without the “treatment” and using DRC instead …

I´ll repeat what’s been said before; DRC will never replace acoustic treatment (at least not if assumed well done) simply because you cannot fix all issues with it (early reflections, decay times etc.). The only option is to treat, but this does not mean that room correction (manual especially) is in vain: It can help to further enhance the room response in a well treated room or help to make a terrible room “manageable” if treatment is not an option.
The general idea in the acoustic community is that nulls cannot be treated with EQ. So why are we seing improvements of nulls here?
Old 7th January 2013
  #408
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Jens Eklund's Avatar
Quote:
Originally Posted by bwo View Post
The general idea in the acoustic community is that nulls cannot be treated with EQ. So why are we seing improvements of nulls here?
General consensus might not always be spot on.

I highly recommend reading the chapter “The limits of EQ” in the REW help file. You might be able to fill a dip more or less completely, but the drawbacks of these actions might trump the benefits. Better to apply correction filters manually and only correct dips that aren’t causing massive distortion due to aggressive boosts with high Q.
Old 7th January 2013
  #409
bwo
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Quote:
Originally Posted by Jens Eklund View Post
General consensus might not always be spot on.

I highly recommend reading the chapter “The limits of EQ” in the REW help file. You might be able to fill a dip more or less completely, but the drawbacks of these actions might trump the benefits. Better to apply correction filters manually and only correct dips that aren’t causing massive distortion due to aggressive boosts with high Q.
Well, SAC normally knows what he's talking about. He's very clear on this. Dips cannot be treated with EQ. And perhaps what we're seing here is just more volume and gain?

Here's what Toole briefly says about it:
Quote:
Attempting to fill deep frequency response dips caused by acoustic cancellations or nulls is an absolutely futile effort, because no matter how much sound energy one pumps into a room the cancellation persists. All that happens is that amplifiers clip, and woofers distort, or worse, destruct. The only solution to this kind of problem is to relocate the loudspeaker or the listener, whichever is sitting in the null.
Old 7th January 2013
  #410
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Quote:
Originally Posted by bwo View Post
Well, SAC normally knows what he's talking about. He's very clear on this. Dips cannot be treated with EQ. And perhaps what we're seing here is just more volume and gain?

Here's what Toole briefly says about it:
Yes, SAC knows what he´s talking about, no doubt, but there are different types of dips, and some can be "fixed" (depending on what one means by that) but at a cost (that often is too high). Distortion and added decay might be too high to be acceptable. Some (or most) dips are better left alone.
Old 7th January 2013
  #411
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DanDan's Avatar
DOH

General Consensus, and SAC, and Toole, say Nulls cannot be filled, or there will be bad consequences.
Tests here and elsewhere show nulls being filled, with no visible or audible bad consequences.

Some of the ground up assumptions are obviously incorrect or context is entirely missing here.

e.g.
There is no general consensus.
SAC did not always know what he was talking about.
Toole is specific. He said deep and caused by. Not all nulls are so simple.

DD
Old 7th January 2013
  #412
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Quote:
Originally Posted by DanDan View Post
General Consensus, and SAC, and Toole, say Nulls cannot be filled, or there will be bad consequences.
Tests here and elsewhere show nulls being filled, with no visible or audible bad consequences.

Some of the ground up assumptions are obviously incorrect or context is entirely missing here.

e.g.
There is no general consensus.
SAC did not always know what he was talking about.
Toole is specific. He said deep and caused by. Not all nulls are so simple.

DD
As long as one is aware that an EQ (or any other gizmoquack) cannot fix all dips, and none without artifacts (higher distortion, limited headroom and possibly a raise of the decay level at fc); do whatever works.

In a way, SAC is definitely right; an EQ cannot fix dips, not without introducing other issues, and that is hardly a complete "fix". Proper treatment on the other hand is, assuming properly done.
Old 7th January 2013
  #413
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DanDan's Avatar
Cannot

I have not seen anyone reasonable claim that DRC is a replacement for treatment. On the other hand it is self evident that first order side and overhead HF reflection are not amenable to Eq at all, but easily treated with fibre, deflection, or even diffusion in boggy's case.
But at the opposite end of the spectrum. Say below 50Hz. DRC becomes a very useful tool. Particularly in the context of the vast number of non pro rooms being used to make records these days.

Let us not forget that the speaker is rarely perfect and very amenable to small corrections. And most of all, the ability to chose one's curve, one designed for and known to promote translation, is the biggest factor of all IMO.

DD
Old 7th January 2013
  #414
bwo
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I'm about to order some Modex Edges og Modex Plates. Should help me to tame pretty low frequencies.
More expensive but better then to rely on EQ.
Old 7th January 2013
  #415
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DanDan's Avatar
Modex

No 'reflection' on RPG, but transport etc. must cost a fortune, but I am about to build some VPR, or CBA, soon.
There are other companies, maybe more local to you bwo, who have the VPR licence to build also.
Willkommen

DD
Old 7th January 2013
  #416
bwo
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Quote:
Originally Posted by DanDan View Post
No 'reflection' on RPG, but transport etc. must cost a fortune, but I am about to build some VPR, or CBA, soon.
There are other companies, maybe more local to you bwo, who have the VPR licence to build also.
Willkommen

DD
Transport cost isn't that bad actually. What really drives the price up is the norwegian VAT, 25% of both the product and shipping. Yeah, Norway is an expensive tax country!

I'm not aware of anyone in Scandinavia that have the VPR license. The company that you linked to have higher prices then RPG. Someone should buy the license and produce them in a low cost country. Same with quality diffusors in wood.

At least I know what I'm getting. DIY is always much cheaper of course, but when it comes to this kind of product I don't trust neither my own skills or the info you find on forums.
Old 7th January 2013
  #417
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DanDan's Avatar
Local

I suspect the RPG product is actually made by Renz....LOL.

A good friend acoustician uses the Modex frequently. He thoroughly recommends them.

From Gernot's experiments it has become clear that corner mounting works very very well. https://www.gearslutz.com/board/bass-...ml#post6791400

Fraunhofer's patent and RPG recommend mounting these devices firmly to a boundary. Hmmm, another confusing contradiction.
Bwo, when you get them, I (and many others in the VPR thread I am sure) would love to see them tested, in corners, leaning against a wall, firmly attached to same wall.

DD
Old 12th January 2013
  #418
Gear interested
null argument

My 2 cents -

Saying that nulls can never be corrected with EQ is just too simple and is incorrect. If the dip is small enough and your amps and speakers can handle the increase in power demanded, parametric EQ will work just fine, for some listening positions. Correcting nulls throughout the entire room can also be done with parametric EQ by using 3 or more subwoofers more or less randomly placed so that each excites different modes.

Room treatment works well throughout the room, in that regard, is better than EQ without distributed subwoofers. But room treatment is a big, expensive hassle and makes your room ugly. ARC 2 will smooth the lows, at least in part of the room, for less money and hassle and decor issues.
Old 16th January 2013
  #419
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Quote:
Originally Posted by ferrellms View Post
My 2 cents - Correcting nulls throughout the entire room can also be done with parametric EQ by using 3 or more subwoofers more or less randomly placed so that each excites different modes.
That's about what it's worth.

Welcome to the Phase War.
Old 17th January 2013
  #420
Gear maniac
 

[QUOTE=ferrellms;8628513]My 2 cents -

Saying that nulls can never be corrected with EQ is just too simple and is incorrect. If the dip is small enough and your amps and speakers can handle the increase in power demanded, parametric EQ will work just fine, for some listening positions. Correcting nulls throughout the entire room can also be done with parametric EQ by using 3 or more subwoofers more or less randomly placed so that each excites different modes.

Room treatment works well throughout the room, in that regard, is better than EQ without distributed subwoofers. But room treatment is a big, expensive hassle and makes your room ugly. ARC 2 will smooth the lows, at least in part of the room, for less money and hassle and decor issues.[/QUOTE

3 subs. EQ to fix nulls. WTF? Um, no...that is not the way to go .
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