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 Integrating dual subwoofers and RTA acoustic panels

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Posts : 5
Join date : 2010-07-15

PostSubject: Integrating dual subwoofers and RTA acoustic panels   Mon 6 Sep 2010 - 18:08

Hi Michael,

I've not posted in the techno-zone since I've been away for 8 days and just returned. Will try to catch up.

Would appreciate it if you could provide some info. on the RTA panels. The website says they provide absorption and diffusion. Is the absorption broadband or limited to a narrower part of the sound spectrum? How does the RTA panel vary the angle of sound reflection to achieve diffusion? What percent is absorption? diffusion? Because these panels are so thin, I'm especially curious since I know of no other company that makes/sells acoustic panels that are less than 1" thick and it seems your panels must be using special materials to achieve enough absorption/diffusion in such a thin package.

One thing I noticed after installing the 15"X30" RTA panels was that the very top of the middle and the treble ranges seemed more prominent. This was especially the case with voices and piano. After a lot more listening, to my ears the sound was not as balanced as I thought it should be. My system uses dual subwoofers along with monitors in a two channel stereo setup. Before installing the RTA panels, I had set the sub crossovers and levels and thought they blended nicely with the monitors. After raising the crossover point to around 80Hz and the level control to a slightly higher output, the balance improved and the mid/treble emphasis decreased enough so that voices and the piano sounded more natural to my ears. What connection, if any, is there between adjusting the crossover/level of the subs and the RTA panels? I'm very pleased with the panels and they have made a pleasing difference as I've noted in an earlier post.

Very Happy Goodvibrations
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Michael Green

Posts : 3436
Join date : 2009-09-12
Location : Vegas/Ohio/The Beach

PostSubject: Re: Integrating dual subwoofers and RTA acoustic panels   Mon 6 Sep 2010 - 20:40

Hi GoodVibe

The RTA design along with all my designs are full range. I do this by controlling loose batting and soft pulp materials mixed with harder materials or sonic barricades. The terms reflective and absorptive are more of a marketing thing that fits into the audiophile camp of terms, but the secrets behind the mask are what make my goodies do their thing. The reflective side is more of a neutral full range surface that is there to keep the tonal balance in the pressure zone while the back of the panel does the burning. Here's a secret, loose batting combined with the right materials act as a big sound wave magnet. This magnet is pulling in laminar flow off the surface it is attached to and controlling it with that combo of batting and pulp. Behind the front of the panel is an active barricade throwing the sound back into burning filler till the energy is burnt. When using my type of barricade system against a wall or even close to a big surface the loose batted fibers used burn more even as compared to just a compressed batt or regular cloth covered batt. Audiophile companies seem to loose their marbles when they talk about sound control inside a room. They compare it to sound proofing instead of sound controlling. These 2 worlds are miles apart when it comes to air pressure and delicate sound waves. How much is too much or enough is something that very few have caught on to outside of the tune. I designed the slimline RT Art to fit decor but it can also be used as a serious zone controller if people wish to play. RTA comes with a .25" raise or we could even say (to be audio correct) port. I made this raise to be a general setting for neutrality but if one wishes to tweak it by putting the panels on angles or making the art sit further from the wall they will hear a noticeable change. For example having the Art sit .5" to .75" off the wall can make a substantial bass trap. And as you mentioned the art can be angled making a soundstage shaper out of it.

One thing that is fun to look into deeper as you play is the use of barricade tuning as opposed to direct absorption. Your music content remains much more in pitch when the waves are caught leaving the wall rather than heading toward the wall. Many companies out there make their products to absorb energy before the sound reaches the wall. This can and does rob the music of it's necessary harmonic structures which are what make the music sound real, full size, and in pitch. If the music is distorted on the way to the wall it can never be put back into total alignment. You should almost always have a neutral sounding surface facing the room with the burning material behind it dealing with the sound after it has activated the acoustical boundary source. In other words you are sitting in a space where the biggest component are the walls and you want to tell them how to sound. Making the walls disappear will never happen but making them sound like they have disappeared is a wonderful art.

michael green
PH 702 762 3245
Email mgtune@yahoo.com
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Posts : 5
Join date : 2010-07-15

PostSubject: Re: Integrating dual subwoofers and RTA acoustic panels   Tue 14 Sep 2010 - 9:04

Hi Michael,

Thanks for answering my questions about the RTA panels. Lots of information here to digest. The ‘big’ concept I came away with is controlling rather than “sound proofing” inside a room. Your explanation of “barricade tuning” is very interesting and enlightening. It would be interesting to listen to the actual differences you described when “waves are caught leaving the wall rather than heading toward the wall.” I never would have considered that acoustical treatments that absorb energy before the sound reaches the wall actually have a negative effect on the sound of the music compared to the sound when waves are leaving the wall. Another ‘big’ idea is: “Making the walls disappear will never happen but making them sound like they have disappeared is a wonderful art.”

I’ve read information provided by most of the better known companies who make and sell acoustical treatments for home listening rooms. In almost every case I found there was a heavy emphasis on “absorption”. Although many caution against over treatment, the marketing hype and advice one finds on websites inevitably leads to buying more treatment products. In one case, the manufacturer's on-line calculator recommended that my room would need between 14 and 21 panels to achieve reverb times within an “acceptable” range. I was skeptical and decided to experiment rather than accept this recommendation. Currently, I am using only 6 panels in my room including two 15” X 30” RTA panels and 4 small rectangular bass trap panels that work on the Venturi principle. The engineers who developed these panels found that by “tuning” them they could focus the effect on frequencies below 200 Hz. Both the RTA panels and the bass trap panels are very effective and integrate well with the furnishings in my room. They contribute to a sound that has balanced tonality, good clarity, is open across that bandwidth and that allows me to hear more of music than without them. For me the lesson was: Beware of simplistic formulas that derive how many and what kind of acoustical treatments you need for your room. I’ve experimented with some DIY traps and panels that changed the sound. However, in each instance I didn’t prefer the difference. All of this underscores the importance of not over treating your room.

Based on personal experience, I’ve adopted this assumption: No matter what you are currently hearing in your listening room you will not know how good it is until you hear something better. This poses a dilemma for every serious audiophile: Should you stop searching because you like what you hear and are pleased with your system OR Should you keep on searching for ways to improve the sound by remaining open to new ideas, new technologies and new products. I would add: Before spending a lot of money on components to attain better sound, experiment with ways to control and shape the sound in your listening room. As we all know, expensive components cannot fix acoustical problems.

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