Placement options – Impacts of location, orientation and treatments

And finally, a Psychoacoustic frequency response plot of the before and after at 1 meter, which shows that there is little measurable frequency response impact. Mostly, a slightly smother 1Khz range.

But as seen in the waterfall plots, massive improvements in time domain behavior.

All of which translates into much clearer dialog or vocals, and much improved coherence of the sound from the center.

Conclusions - Center channel improvements

Hopefully by showing you the metrics in both time domain (Impulse and waterfalls) as well as frequency domain (Bode and Psychoacoustic) I’ve shown that there are key benefits to treatments that are easily measurable.

Primarily, it’s the treatment of Resonances, as these totally kill cohesion, and in their most egregious manifestations, can ‘ring’ in the room, totally killing the ability to sustain enjoyable high sound pressure levels.

By treating the rear wall bounce behind the ESL’s, we’ve managed to get a very clear sound from the speaker. Which translates into the improved dialog comprehension.

I feel that often one of the issues with ESL’s for HT is due to people (including me in earlier iterations) not treating the rear wave of the ESL correctly.

I can fairly confidently state that if you have a Stage, Cinema or other open back ESL center, rush to the phones and order one MiniTrap HF and place that on its side two feet behind the center and set off from the wall by three inches. This is guaranteed to improve your dialog perception.

JonFo said:

............
By treating the rear wall bounce behind the ESL’s, we’ve managed to get a very clear sound from the speaker. Which translates into the improved dialog comprehension.

I feel that often one of the issues with ESL’s for HT is due to people (including me in earlier iterations) not treating the rear wave of the ESL correctly.
...........................

Click to expand...

I agree, as even with my crude room treatments behind the speakers, I noticed a distinct clearing up of vocals on music (I'm not at all into HT).

HF vs non-HF

One of the tests we wanted to make was to determine the benefits of the HF version vs the non-HF. As our member Rich had stated earlier, the non HF version was not at all to his liking and he vastly preferred the HF version.

Here’s why. The non-HF versions of Mini’s and Mondo’s contain an internal diaphragm to improve its low-frequency absorption characteristics.
However, when placed behind an ESL, that reflective surface provides a large reflected spike in the response dependent on distance. This causes comb filtering, resonances and other anomalies that destroy the clarity of the sound.

The HF version does not have the reflective element and is more absorbent in the high frequencies.

The best way to illustrate the difference is to again look at a time-domain view of the responses in a waterfall plot.
The top plot is the Mondo trap two feet behind the SL3XC, the bottom plot is the MiniTrap HF at the same location.

Clearly, the HF Mini is the more effective of the two, as there are minimal resonances in this configuration.

And just in case it was not obvious what a difference it makes, here is an animated version of those waterfall plots.

Interestingly, if one were to look at just the frequency response plot shown atatched, we might have said that the blue trace, for the reflective Mondo trap, would be preferred, as it has a flatter overall response. It clearly can absorb more bass energy than the MiniTrap.

But as we’ve seen in the waterfall, it’s not all about just the frequency response, is it?

The MiniTrap HF has less energy in the high frequencies, but that’s due to the lack of resonances. It is also slightly smoother in the critical 500Hz to 5Khz region.
The bump at 100+ would be addressed by other in-room treatments.

It’s a balancing act, that’s for sure.

Excellent work, Jonathan. Ethan owes you a debt of gratitude for posting such great evidence of the efficacy of his product. I can't wait to see your data from whole-room treatments once you get the rest of your product in and installed. I also can't wait to come back over and hear the difference.

Your measurements confirm what I already realized from personal trial and error -- that the HF mini traps are the way to go behind the panels because they evenly absorb from 250 hz. on up. You have also debunked what I believe is one of the biggest myths in ESL circles -- that the rear wave of the panel provides an "ambiance" that is beneficial to the sound.

Those members with bare wall or straight diffusion behind your MLs should take notice. Your imaging and soundstaging are being smeared by reflections from the front wall. It is amazing how much more clear the image is when the rear wave is absorbed. Think of it as if you had two sets of speakers playing the same music, but one set was located about two to three feet behind the other. The result is a complete smearing and blurring of the image. Diffusion isn't the answer either. At the distances that we sit from the speakers (less than 10-12 feet) diffusion isn't going to be effective at scattering the sound enough to prevent image smearing.

Before you think about spending several thousand on an upgraded cd player, preamp, amps, etc. to get better sound, spend a few hundred and put some full frequency absorbers behind your main speakers. The improvement in sound will be jaw-dropping.

Rich said:

Excellent work, Jonathan. Ethan owes you a debt of gratitude for posting such great evidence of the efficacy of his product. I can't wait to see your data from whole-room treatments once you get the rest of your product in and installed. I also can't wait to come back over and hear the difference. …

Click to expand...

Rich, thanks and you’re welcome to come over as soon as you can make it. It is indeed getting much, much better.
Just pack those Sanders amps with ya when you do come

Rich said:

Your measurements confirm what I already realized from personal trial and error -- that the HF mini traps are the way to go behind the panels because they evenly absorb from 250 hz. on up. You have also debunked what I believe is one of the biggest myths in ESL circles -- that the rear wave of the panel provides an "ambiance" that is beneficial to the sound. …

Click to expand...

I am still hopeful that there is something positive to be done with the rear wave, but I have to agree that the data so far is looking like ‘soak it up’ for the rear wave.
Even if one can do something positive, it will likely be complex geometries and device configurations. Aesthetically pleasing it will not be. (to quote Yoda).

I do feel the evidence is clear that a ML in front of a bare wall is a definite no-no.
Toe-in will mitigate some of the worst effects, but still...

Rich said:

... Before you think about spending several thousand on an upgraded cd player, preamp, amps, etc. to get better sound, spend a few hundred and put some full frequency absorbers behind your main speakers. The improvement in sound will be jaw-dropping.

Click to expand...

Amen to that brother!

I have always treated the rear wave in some form or fashion, but regrettably, not until now with a truly outstanding product. The difference is significant. And I agree; way more impact than any other piece of gear one could obtain.

The lesson here is the room is a huge part of the sound equation, almost more so than any other piece of gear. And even custom rooms like mine, which was designed for these ML’s, all need further treatments to get the best out of them and the associated system.

And here's a pic of the installed MiniTraps HF behind the screen.

you can see the MondoTrap on the bars holding the screen at the top.

JonFo said:

Yesterday (Saturday) FedEx pulls up at 5pm and starts to unload a literal truckload of boxes.

Click to expand...

Thanks much for the detailed report. My only comment is you could try a longer gate time for the waterfall plots. That will show more detail, and better show the difference between before and after. For low frequencies I generally use 200 ms. Other than that, looking good!

--Ethan

Ethan Winer said:

Thanks much for the detailed report. My only comment is you could try a longer gate time for the waterfall plots. That will show more detail, and better show the difference between before and after. For low frequencies I generally use 200 ms. Other than that, looking good!

--Ethan

Click to expand...

Hi Ethan, Sure, no problem. I'll add some additional waterfalls with longer gating in the am.

Until I treated the whole room, I was sort of ignoring the bass for the time being. Since it's primarily a room wide phenomenon.

I finally unpacked the rest of the traps, so now have the rear corners treated with four Mondo traps and finished up the front by placing two MiniTrap HF’s behind each Monolith and some MiniTraps (regular type) along the side wall, but still towards the front of the room behind the Monoliths.

Sounding even better than this morning and last night. Can’t wait for the additional corner Mondo traps to hang along the ceiling-wall intersections the length of the room plus the four corner TriTraps. And the final coup-de-grace, the two near-field diffusers for the rear of the room.

The biggest change I detect now is that the ‘image’ is so much clearer and cohesive. I paid a lot of attention to time delays in the speaker processing to ensure totally aligned impulses from each speaker (and speaker element), but the room smear from the resonances was masking the benefits to a large extent. It’s now really clear that the speakers are aligned just right. Triangle hits or cymbals in the front three speakers are totally synched. Even front to back synchronization is improved with the trapping so far.

I still need ceiling treatments as well as additional side wall work. But that will be DIY plus some additional commercial products.

Great products, great results Ethan. Thanks.

Rich said:

Your measurements confirm what I already realized from personal trial and error -- that the HF mini traps are the way to go behind the panels because they evenly absorb from 250 hz. on up. You have also debunked what I believe is one of the biggest myths in ESL circles -- that the rear wave of the panel provides an "ambiance" that is beneficial to the sound.

Those members with bare wall or straight diffusion behind your MLs should take notice.

Before you think about spending several thousand on an upgraded cd player, preamp, amps, etc. to get better sound, spend a few hundred and put some full frequency absorbers behind your main speakers. The improvement in sound will be jaw-dropping.

Click to expand...

Rich, I could not agree with you more as I have always like absorption behind my panels, and now as you and Jon have also found out. I know there are some who still like diffusion and people should still try both to see which they prefer.

Jon's results helps with showing folks the benefit of absorption and room treatments for better sound. Great post Jon!!! :rocker: Thanks for the hard work and showing the true benefits of acoustic treatments to a room.

People should also note you can start with just a few panels in your room to get started on better sound. You can add panels over time as the budget allows.

Dan

There is a great thread on the topic of difussion vs absorption over on the AudioCircle forums:

http://www.audiocircle.com/circles/index.php?topic=44098.0

The thread initiator has a pair of large Maggies (3.6r) they are setting up and treating.

DTB300 said:

...
Jon's results helps with showing folks the benefit of absorption and room treatments for better sound. Great post Jon!!! :rocker: Thanks for the hard work and showing the true benefits of acoustic treatments to a room.

People should also note you can start with just a few panels in your room to get started on better sound. You can add panels over time as the budget allows.

Dan

Click to expand...

Thanks Dan. It’s been fun doing this.

For complex systems, I like to document the process of arriving at a conclusion so I can evaluate as objectively as possible whether my chosen solution is the right one. It also allows others to review and give feedback, which just improves the chances of getting something right.

What I’m also hoping we can do is to collectively bring together much of this data in a synthesis of recommendations for ML owners. That would then save people from having to read hundreds of posts with esoteric metrics in them

Tom, we need a Wiki on this Forum !

And Dan, yes you’re right, starting small, with a few panels is a good way to go. Just keep adding them as time and budget allow. Even a few, placed in the right locations will make a noticeable difference.

I am a member over at Audio Circle and haven't posted here in quite some time, since I have taken my CLSes out of service for my new system. I just wanted to mention that I have found that the proper mix of both absorption and diffusion do work quite well in my room with all the dipoles that have been set-up there. Those systems have been the Infinity RS1bs, CLS1s and my new VMPS Reference System.

The VMPS is a bit different as it does have diffraction wings similar to the Infinity and Genesis systems, but they are folded back creating a rear horn for the back wave. They are toed in slightly and have 12" tube traps and artificial plants sharing the space along the wall behind them. One wouldn't think that these tall plants would do a lot, but in my room they really help to dial in the soundstage focus to a sharp degree.



For some reason this photo I am trying to post gets turned into a banner for the audio Circle?
So, let me post a link to a thread that shows them:

http://www.audiocircle.com/circles/index.php?topic=43744.0:

Dave

JonFo said:

There is a great thread on the topic of difussion vs absorption over on the AudioCircle forums The thread initiator has a pair of large Maggies (3.6r) they are setting up and treating.

Click to expand...

Most of the time I have seen Maggie owners preferring diffusion behind their speakers.

JonFo said:

And Dan, yes you’re right, starting small, with a few panels is a good way to go. Just keep adding them as time and budget allow. Even a few, placed in the right locations will make a noticeable difference.

Click to expand...

The entire process should prove to be very interesting for people to read and follow. Now getting people to come over to the "Dark Side" and reap the benefits of acoustic treatments is another story. Hopefully this will help prod them to try it out and see for themselves how great an improvement in the sound of the setups it can be.

Great read so far ! Thanks Jon . I have had 2 pairs of Maggies and they really needed back wave absorption to help them out. The room also had a big factor in where the ribbon was placed . Inside or outside.

They are a bit more room conscious than the Logans.
I may play with some treatment soon as I have to get used to the newly designed speakers I have made ! More to come about them soon.

LF Waterfall plots

As Ethan suggested, Here are the two waterfall plots of the untreated room (bare wall behind center, no other traps), vs 4x MiniTrap HF's (but none of the others) installed.

These have a 200ms gate time and show the 10Hz to 500Hz low frequency window.

Note that many of the bass resonances (long decays) are improved upon with just the Minitraps in place. But the big impacts will not be seen until the entire room is treated with the 4x Mondo traps in the rear + the 4x Corner Mondo Traps that will go along the ceiling/wall juncture + the 4x TriCorner traps.

Top Chart is before, bottom chart is after treatments.

I firmly believe that the room is a major component to the system. If you do not spend the time and resources to get that as acoustically correct as you can first, not much else matters. Because, the best component will not perform near to its potential otherwise. Room treatments = music.

I own a pair of ML Summits and still have a lot to learn about audio fidelity. I found your postings on room treatments enlightening, and I was hoping you could clear up some concerns I have about the quality of the Summits that may be reflected in your measurements.

I recently came across Richard Hardesty's www.audioperfectionist.com online publication where he argues that Martin Logans exhibit poor (quasi-anachoic) frequency responses, poor time and phase performance, and significant energy storage issues that are inherent to their design. He argues that it makes them inaccurate speakers and listeners confuse this with being highly-detailed. DTB300 seems to refer to this effect as "one of the biggest myths in ESL circles -- that the rear wave of the panel provides an "ambiance" that is beneficial to the sound". Hardesty's measurements were taken for a Martin Logan Aerius.

My question is whether you know of any published quasi-anachoic response measurements for the Summits? Whether the Summits perform as poorly on the speaker response tests as the Aerius? And if so, whether it's best to start with a better (anachoic) performing speaker in the first place before investing in room treatments or any other improvements?

I guess ultimately my question is whether room effect treatments can overcome speaker performance deficiencies? Or are room effects so much more important than speaker deficiencies among “decent” speakers that fixing room effects has a bigger incremental benefit than starting with better performing speakers?

I do understand that fidelity is more than just measurements. That it’s also about personal sound and musical preferences, budgets and inherent speaker design constraints. However, I too am thinking of pursuing direct speaker measurements to improve the quality of my system and would appreciate your opinion on this matter. Thanks.