Super Tweak for RM40 = Lapels and Hood

BrunoB · « **Reply #20 on:** 30 Jun 2003, 01:55 pm »

Quote from: Brian Cheney

I considered foam masks on either side of the mid panels, but realized it would take a full 3" thickness to be effective down to 200Hz, cosmetically not an enhancement.

Just an idea to hide the foam:
If the drivers would stick out by 3'' from the cabinet (the mid enclosure could be placed 3 '' farther out, the woofer and HET could be placed on a 3'' tall cylinder), then the 3 '' thick foam could be attached on the front plate and be covered by an acoustically transparent fabric matching the speaker finish.

Bruno

Horsehead · « **Reply #21 on:** 30 Jun 2003, 06:11 pm »

Thanks for the reply John. Foambymail.com also has the 3" Wedge foam in a 24" x 48" x 72" sheet for $115. That should work just the same I think. Also- I don't need the extra foam since I just treated my entire room with Eighth Nerve Products- they work very, very well.

What do you think of this product under the RM40s?
http://www.symposiumusa.com/svelte.html
Just scroll down to placement under speakers.
I own a couple of there products and think they are quite good. Symposium is about 20 miles from where I live, so I thought about giving them a call to try the Svelte shelf under the 40s and see what happens.

JoshK · « **Reply #22 on:** 30 Jun 2003, 06:35 pm »

The first time I read "Lapels and Hood" I wasn't thinking audio!

PLMONROE · « **Reply #23 on:** 30 Jun 2003, 08:16 pm »

How about this foam crown molding for the wall to ceiling junctures. Would this also be of benefit?

Horsehead · « **Reply #24 on:** 10 Jul 2003, 04:23 pm »

I just got my 3" foam from foambymail.com and installed the tweak. First off, the foam is difficult to get a factory straight cut, so this tweak definitely doesn't get any beauty awards. My wife's reaction was, "What the hell is that!?" She went on further to say that with all of the Eight Nerve Products in the room, it looks like I am in a padded asylum room at the mental ward (she's not too far off with her diagnosis).

I ordered two sheets of 24x48x72 inch foam and was able to cut continious strips to go on the baffle. In John's photos it looked like he pieced two strips together to cover the length of the baffle. I used small Velcro squares to attach the strips to the baffle. They stick to the foam and leave no residue on the baffle as I tried to peel one off.

The tweak does work. I had my RM40s toed-in so they cross about 2 feet in front of me. After the tweak was installed something was not right for me. Vocals took on a nasal quality and lost a lot of air around them. I readjusted the toe-in so the speakers were crossing at my position and everything came into place. The soundstage is more focused with greater "individuality" of instruments within the soundstage. Vocals are natural, clean, and free of any glare. So far I have not noticed any negative effects and I am really enjoying my RM40s a little bit more. In my system, it certainly did not produce dramatic effects, but that last little 1 or 2% improvement is realized. It certainly is easy and cheap and can be taken off when not in use or if it doesn't work. Can't really explain the toe-in differences, but they were necessary after the foam was put on. John, maybe you can verify this with your pair? All I need now are those FST dressplates.......

Bravo John!

John Casler · « **Reply #25 on:** 10 Jul 2003, 08:41 pm »

Quote from: Horsehead

Thanks for the reply John. Foambymail.com also has the 3" Wedge foam in a 24" x 48" x 72" sheet for $115. That should work just the same I think. Also- I don't need the extra foam since I just treated my entire room with Eighth Nerve Products- they work very, very well.

What do you think of this product under the RM40s?
http://www.symposiumusa.com/svelte.html
Just scroll down to placement under speakers.
I own a couple of there products and think they are quite good. Symposium is about 20 miles ...

Hey Dave,

I just saw this question.

I would tend to not think that these would help the RM40s all that well, but who knows.

My take on speaker vibration tweaks is generally to "mechanically couple", increase mass, and reduce actual cabinet resonances (not dissipate them by "suspension")

I see increasing cabinet rigidity, inertness and speaker weight as key.

But who knows it might work like a champ. If you try it let me know.

John Casler · « **Reply #26 on:** 10 Jul 2003, 08:43 pm »

Quote from: JoshK

The first time I read "Lapels and Hood" I wasn't thinking audio!

Wait till you see the "Top Hat" and "Tails" I have coming out soon

John Casler · « **Reply #27 on:** 10 Jul 2003, 09:06 pm »

Quote

The tweak does work. I had my RM40s toed-in so they cross about 2 feet in front of me. After the tweak was installed something was not right for me. Vocals took on a nasal quality and lost a lot of air around them. I readjusted the toe-in so the speakers were crossing at my position and everything came into place. The soundstage is more focused with greater "individuality" of instruments within the soundstage. Vocals are natural, clean, and free of any glare. So far I have not noticed any negative effects and I am really enjoying my RM40s a little bit more. In my system, it certainly did not produce dramatic effects, but that last little 1 or 2% improvement is realized. It certainly is easy and cheap and can be taken off when not in use or if it doesn't work. Can't really explain the toe-in differences, but they were necessary after the foam was put on. John, maybe you can verify this with your pair? All I need now are those FST dressplates.......

Glad you had a chance to try it. I too found that it added the final lines of defining properties to the images. And it seemed to provide a blacker space between instruments and performers.

Did you also place the hood on top to reduce the ceiling bounce?

This whole thing started when Tyson ask if he could get an RM/x "scooped out" front baffle on the RM40. I thought the only way to (in tweak fashion) approach the same effect would be to block/absorb most of the sound energy that is reflected off the front baffle.

Since I always listen to my RM40s in a "nearfield" on axis postition anyhow, I didn't find any of the symptoms you describe.

But, if I use the rear "sweet spot" where they do cross in front of me, since it is about 9-10 feet from the speakers, I still didn't get any sonic degradation.

In fact it works quite well in all three SS positions in my room (no side walls)

rblnr · « **Reply #28 on:** 12 Jul 2003, 04:11 am »

www.markertek.com sells their house brand of foam available in 54"x54" x 3" sheets for $30. I've made several acoustic panels out of their 24" x 24" blade tiles; I glue the foam squares on a piece of louon then cover with nice fabric for wife approval. Much cheaper than buying prefab. sound panels. Also use the corner bass traps Markertek sells which I find cheap and effective.

Markertek is also a great source for cable; canare, belden, etc. w/all kinds of high quality connectors. Have been using them for pro film/video equip. for many years.

BrunoB · « **Reply #29 on:** 19 Jul 2003, 05:48 pm »

Quote from: mcm7

Quote from: BrunoB
My speakers are 626R with black finish. Instead of using foam, I am using a black bathroom rug (microfiber, bought at SEARS, $30). Presently, two cutted pieces of rug are hold with a rubber band on the each side of the mid panel of my 626R for testing. I plan to cover the whole front panel of the speaker using a complete rug....

Bruno, please post pictures of your Rug-tweaked speakers!

The speakers look weird (a black bear with a beard)

but the rugs can be removed after"serious listening" (but I always keep them). I used velcro for the other speaker and the rug can be put on and off at will. The velcro is stappled to the backside of the rug otherwise it would not hold. On the speaker surface (glossy black finish), I had to use a larger surface velcro because it does not stick well. The rug is attached on the side of the speaker only. I have other pictures in my gallery.

Note that removing the tweeter grey foams is not easy - I damaged one pair.

Bruno

audiochef · « **Reply #30 on:** 23 Jul 2003, 12:18 pm »

Hi horsehead, what you describe on the affects of the platforms is very similar to yhe affect I got with the new bases.

James Romeyn · « **Reply #31 on:** 24 Jul 2003, 02:54 am »

At my place reversing the woofers (midbass down low, Megawoofer up top), improved the sound immensely. In the OEM positions, there was too much midbass & low mid from the top, especially bouncing off the ceiling, as Dr. John describes. Also, the OEM positions cause a subtle but quite noticeable upward image shift when the musical output concentrates in the 10" midbass range. The mod is a pain the arse & worth every bit. Credit to the Mrs. for complaining about the image shift in the first place. I posted very detailed instructions a long time ago.

Tyson · « **Reply #32 on:** 24 Jul 2003, 07:01 am »

I thought the upper and lower woofers operated in parallel from 166hz down to 80hz or so, w/the lower woofer extending further down to 35hz or so (w/the PR taking over to 24hz). Is this not correct?

James Romeyn · « **Reply #33 on:** 24 Jul 2003, 05:10 pm »

Correct & incorrect. The two woofers "operate" in parallel, but their output is frequency dependent.

There are two paralleled woofers sharing a single 6dB XO, but the Megawoofer's double-magnet lowers its frequency AND sensitivity vs. the MB. This is the woofer designers highwire act: lower frequency vs. higher sensitivity. As frequency decreases, output skews toward the MW. As frequency increases, output skews toward the MB. Play a test tone or music concentrated around 160Hz. Put your ear close to one woofer then the other. I estimate 3-6dB disparity at 160Hz.

The first order XO = output beyond 160Hz. The higher the frequency the greater the output disparity between the woofers. At 320Hz the MWs about dead, while the MB is singing. To hammer this home, turn off the ribbons & listen to the woofers only. Ceiling bounce negatively affects the midrange. Where is your pesky MB located right now? Middle C is 261.63Hz (Harry F. Olsen). Because of the ribbons' narrow vertical dispersion, most of the 40s ceiling bounce emanates from the MB.

Swapping woofer locations improved the sound equal to the difference between moderately badly tuned & razor-sharp tuned. Considering the positive results here, I posit that it is worth duplicating by several 40-owning audio-fanatics, especially those having crummy 8' ceilings like your humble audio correspondent. If a critical mass of owners get even a portion of the upgrade I did, Brian could be hammered till he cries uncle & swaps the woofer locations, saving future owners the hassle. I apologize that my high-school wrestling moves failed to persuade Brian, & my "friends" Carmine & Giuseppe are extending their vacation at mama's house near Lake Como. Mama's cooking has only improved, & she is still working on the boy's laundry from early 2003.

The mod requires patience. I will email excruciatingly over-detailed instructions in an attachment. It's not as effortless as you might think, but then again, is it not always such? Worth every effort required IMHO. And look at it this way, my Aprillia track bike needs a lot of fine suspension tuning for decent results, & the tuning goes on indefinitely.

JoshK · « **Reply #34 on:** 24 Jul 2003, 05:58 pm »

Jim,

This is what confuses me on paper about your tweak. If you swap positions of the MW and the MB wouldn't you be trading ceiling bounce for floor bounce?

Tyson · « **Reply #35 on:** 24 Jul 2003, 06:05 pm »

You are correct, floor bounce will be a pro blem, but will be ameliorated to a large extent if you have thick carpet like I do. I'm going to try the switch, see if it gives me even a little more midbass than I am getting now (due to boundary re-inforcement). Jim, can you email me the directions?

James Romeyn · « **Reply #36 on:** 24 Jul 2003, 06:24 pm »

Quote from: JoshK

Jim,

This is what confuses me on paper about your tweak. If you swap positions of the MW and the MB wouldn't you be trading ceiling bounce for floor bounce?

Most have carpet, absorbing the upper MB output & minimizing floor bounce. Regardless of floor reflectivity, floor pathlengths are shorter, meaning higher in frequency vs. the ceiling. The MB output extends higher compared to the MW, but the MB output still attenuates as frequency increases.

Horsehead · « **Reply #37 on:** 24 Jul 2003, 06:50 pm »

Hi Jim- Nice to see you posting again on multiple threads.
Are the directions basically the same as you have outline in this thread at HD?
http://www.harmonicdiscord.com/forums/viewtopic.php?t=10394

John Casler · « **Reply #38 on:** 24 Jul 2003, 07:03 pm »

The reason I tried the "hood" tweek" (tweak) was to reduce ceiling reflection. It is a "very simple" and effective way to deal with this issue if your room has it. Although it is not by any stretch "attractive", it can be placed on the speaker for serious listening in seconds and thrown in the nearest closet, when done.

The amount of control is also adjustable by simply increasing the amount of "overhang". (I found about 6" worked the best overall)

And the adjustment Jim mentions is rather involved. (removing both woofs, unhooking, rehooking, resealing and mounting)

The other reason I opted for the simple foam was:

According to Brian, switching the woofs will produce a substantial lowering of bass overall. I think he said 3-5 db (not sure about that number)

This would seem to come from taking the "reinforcing" floor boundary away from the Low Bass Megawoofer. Since I have my speakers well out from the wall, I need all the bass I can get, so it wasn't agood option.

Jim, what did you do to ameliorate these resulting affects?

wshuff · « **Reply #39 on:** 24 Jul 2003, 08:04 pm »

Kudos to both Tyson and John C. for use of the word "ameliorate" in the thread. It's nice to get an English education along with the hi-fi knowledge.

Seriously, don't any of us work? What are we doing here?