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Old 23rd August 2009, 05:45 AM   #1
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Default Calling BudP - enabl vs room modes

Sir, I'm very interested in some specific comments you have made about the qualities of bass reproduction once this procedure has been performed and I'd appreciate a bit of clarification. I have a big problem and if enabl alone can solve it I am very willing to experiment and share the results.

I have massive room mode issues. I have a fairly small untreated room, bass treatments are not an option in this situation. You have mentioned in the past that enable can help with that. It is beyond my comprehension how this could be possible but I'm willing to try if there's a chance.

These are the specific comments I'd like you to either confirm or clarfy. The first was quite awhile ago in a different forum (describing the effects of enabl'ing the driver only), the others are from very recently in the BIB thread.

Quote:
Bass will absolutely cease rumbling, no matter the enclosure type. In it's place you will find deeply textured information, with startling transient punch. Room resonant nodes will cease to be excited, all of them. Bass note null zones are past history.
Quote:
Treating the inside of the cabinet will provide benefit all out of proportion to what it should, for coherence from both the speaker and the port. Treating the cabinet face around the port and in the port and inside of the cabinet will also help with bass clarity...
Quote:
Treating the room walls can be done in a couple of hours, with self tacking, clear cabinet lining plastic sheeting, cut into appropriate sizes.
I can do any or all of these things, measure, post the results. I have inverted BIBs to use. I can enabl the drivers and most of the inside of the enclosure, the entire outside of the enclosure, the room, and if necessary even the furniture, windows, door frames, closet.

Before I do this, I'd like to be very clear that you think this will work for the purpose of measureably eliminating room mode issues. I'm not interested in any other benefits or consequences of the procedure.

I am willing to follow any specialized instructions you care to give to encourage best results and look forward to anything you have to say on the subject. Or it could be as simple as picking one of the following 4 statements and I'll follow previously posted instructions, measure, post results.

a) Enabl'ing the driver alone will completely remove any room mode issues you might have. They will no longer be measureable.
b) Enabl'ing the driver, inside of the cabinets, outside of the cabinets, and the room will remove all room mode issues.
c) It's really not that simple, enabl'ing everything you can will help things measureably but you still need some real treatments to completely eliminate any trace of problematic modes.
d) Enabl will not measureably reduce room mode problems.

Thanks in advance for your time.

Last edited by just a guy; 23rd August 2009 at 05:52 AM.
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Old 23rd August 2009, 10:57 PM   #2
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Still wondering.
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Old 23rd August 2009, 11:36 PM   #3
MJK is offline MJK  United States
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d. No effect on room modes.
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Old 23rd August 2009, 11:44 PM   #4
cuibono is offline cuibono  United States
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D.

Best if you got a measurement mike, and did some active EQ of the bass in your room.
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Old 24th August 2009, 04:18 AM   #5
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Cuibono, thanks, I'm already doing that, it's not enough.

MJK, thanks, this is what I suspected. I was really hoping though, and willing to entertain the idea because I can't disprove it but at this point I don't think I need to and no point in trying.
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Old 24th August 2009, 05:23 AM   #6
BudP is offline BudP  United States
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Sorry, I had not seen this till this evening.

First problem is measurable. How will you measure and what room modes will you measure and where?

If measurable means intelligible, then we have a chance.

Enabl'ing the, I assume, full range driver, will cause the room bass nodes to drop in their response to resonant behavior from the speaker. The typical result is that the hot spots are mitigated, You will still have variability in bass from position to position, but the null zones that arise in many rooms, will be greatly dispersed. At the same time, the intelligibility of the bass will increase. Not the spl, not the frequency response, the intelligibility. Bass notes are not comprised of just low frequencies and EnABL'ing a driver causes more coherence to the entire signal, so bass will come along for the ride.

EnABL'ing the port, if it is big enough in size to allow something sensible in block size to be used, a circumference of at least six inches or more, will provide another large reduction in room resonance activity. Walls will cease to be hot zones, previous null zones in the room will be much less prevalent. Bass will become more intrusive and with considerably less false information. It will actually sound as if there is less bass initially. Then it will dawn on you that it is still shaking things in the room, but it is doing so in consonance with the musical signal, rather than as a jumble of low frequency ringing. Just less low frequency noise.

Treating the box face around a port will add further clarity to the bass and patterning the entire baffle will add more and also cause the speaker to audibly disappear. There will still be cellular room resonance activity left over. It will be very benign compared to no treatment.

If your listening room has no absorbent materials in it, I doubt EnABL will do more than reduce the degree of rumbling around.

I have not treated a room with EnaBL blocks. I suggest you PM Alex from Oz and ask him to respond here. He will. I have a customer in Notrth Carolina, who has taken the Fostex F200A drivers I treated for him and moved on to treat the internal and external walls of the simple transmission line cabinets they are mounted in and then out into his room, on various pieces of equipment and walls. His opinion is that every EnABL'd surface reveals more detail in the sound field, once the drivers and cabinets are done. However, he did add bass traps, but cut in half and arrayed on the back wall and was most satisfied with this addition to the room treatment.

I can provide you with a PM email if you like, after I clear it with him. I do have a number of pictures from him too.

I would suggest you use clear acrylic plastic shelf covering material for all cabinet and wall treatment. It is only 0.003" thick and has a stick and release adhesive on it. Cheap to get, easy to apply, except for getting the paper backing off of the plastic, and can be removed and thrown away if it turns out I am lying or deluded. Do the cabinet, the port and the room walls to Alex's specs. If this has helped, then do the drivers.

Anyone with a conventional understanding of the physics that underpin speakers and rooms, is going to get pretty upset about these comments of mine. I do not blame them, at all.

Bud
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Old 24th August 2009, 06:10 AM   #7
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Quote:
First problem is measurable. How will you measure and what room modes will you measure and where?
I measure from the listening spot with the speakers set up in corners (w/ the BIBs). I have massive modal problems at aprox. 55, 110, 220 hz. These peaks can measure 15 db or more depending on which speakers (or subs) are used and placement. The highest one at 220 hz is by far the most objectionable, making it sound like the mic is shoved way up the performer's nose. The lowest one at 55 hz is usually not too problematic unless subs are being used.

What I am looking to accomplish is a real measureable reduction of these modes. If you think this is possible I'll try it. If it will provide a cleaner sound but not actually measureably reduce the severity of these peaks I respect that but it's not what I'm looking for right now because regardless of the quality of sound the speaker produces it won't sound good with 15 db modal peaks.

The room is heavily carpeted with nothing else soft in it.

Last edited by just a guy; 24th August 2009 at 06:15 AM.
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Old 24th August 2009, 06:19 AM   #8
BudP is offline BudP  United States
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Let's await Alex on this. I have pinged him and asked for his advice. The first thing I would try is a set of patterns in the corners, but this is just from reading his accomplishments in what sounds like a room similar to yours. Your investment will be less than $5 to attempt this.

Now, how did you get yourself into a fix like this?

Bud
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Old 24th August 2009, 07:15 AM   #9
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Quote:
Originally Posted by just a guy View Post
What I am looking to accomplish is a real measureable reduction of these modes. If you think this is possible I'll try it. If it will provide a cleaner sound but not actually measureably reduce the severity of these peaks I respect that but it's not what I'm looking for right now because regardless of the quality of sound the speaker produces it won't sound good with 15 db modal peaks.
G'day just a guy,

I have done a lot of work over the last 18 months with EnABL on fixed surfaces including ports, baffles, inside cabinets and room corners.
Each of these can and does make an audible difference to the bass in the room.

Here are some posts on EnABL room corner treatments:*
http://www.diyaudio.com/forums/showp...&postcount=261
http://www.diyaudio.com/forums/showp...&postcount=323
http://www.diyaudio.com/forums/showp...&postcount=363

*The speaker cones and cabinets were fully EnABL'd before I applied the corner treatment.

Here is my treatment for BIBs:
Extreme BIB cabinet EnABL

You are very specific that you are only interested things measureable regardless of other sonic benefits.
I don't have measuring gear so i can't answer that question specifically.

Bud's suggestion of doing the room corners first is the easiest approach.
1. Treat one corner behind the speakers first, then listen in stereo.
If things sound strangely unbalanced, then you are hearing the effect of the EnABL.
2. Treat the corner behind the other speaker and listen in stereo - things will sound balanced again, but different compared to pre-EnABL.
3. Do the remaining back two corners - then listen in stereo again.

At this point, you may want to fire up the measuring gear.

If for some reason you can't hear a difference immediately, leave the corner patterns in place for at least a couple of weeks.
Then, remove them all at once and listen in stereo.

Cheers,

Alex

Last edited by Alex from Oz; 24th August 2009 at 07:18 AM.
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Old 24th August 2009, 07:02 PM   #10
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Thanks Bud and Alex for taking the time to discuss this.

Quote:
Anyone with a conventional understanding of the physics that underpin speakers and rooms, is going to get pretty upset about these comments of mine. I do not blame them, at all.
I have to admit that based on what little conventional understanding I possess I'm not expecting this to have any effect on my modal problems. BUT if there's any chance it could help at all I'd be foolish to ignore it, especially considering the low cost to try it out.

Quote:
I would suggest you use clear acrylic plastic shelf covering material for all cabinet and wall treatment.
If there is no objection I would prefer to use green painter's tape. If it doesn't work it hopefully will not ruin the paint on the walls when I remove it. If it does work I may leave the tape on the walls and paint right over it.

Quote:
You are very specific that you are only interested things measureable regardless of other sonic benefits.
I have really big measureable problems and I don't think anything is ever going to sound right unless I measureably eliminate these problems. Parametric eq is my friend but it's not enough, it can't do anything to resolve excessive sustain in the time domain. This is my focus right now.

I'll take some time now to read the linked info and proceed with caution.
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