You can expect dramatic results . For $700 of rigid owens corning 2 inch thick 2'x4' you can go floor to ceiling in all 4 corners. google superchunk bass traps. or you can by ready made ones for that price for just one trap that will cover one quarter of one corner .
12 responses Add your response
Thank you for your reply.
Forgive my ignorance, but what are room modes?
I am using a Lexicon RX7 and a Yamaha CXA-5000 processor.
My front speakers are a set of Monitor Audio PL100's and GXC350 center. The PL100's sit on to of heavy granite stands on top of each SVS Sub Ultra 13, right and left of the TV & Sunoko Vent AV rack facing me.
I hope this helps. Do you need more info?
You can do a web search on room modes and find a lot of information. Here's one instance: http://en.wikipedia.org/wiki/Room_modes
For a good discussion of room modes and bass, consider reading Dr. Toole's "Getting the Bass Right" paper here: http://www.harman.com/EN-US/OurCompany/Innovation/Pages/WhitePapers.aspx?CategoryID=White%20papers
Basically, it is the interaction of sound waves within a bounded space, i.e., your listening room. The net effect at your listening position may be that the SPL is either higher or lower than it would be in free space. The goal of room mode correction systems, i.e., equalization, is to reduce the positive and negative fluctuations in SPL at your listening position.
Since bass frequencies have relatively long wavelengths, it is the bass that excites room modes in typically sized listening rooms; generally frequencies below 350 Hz.
Equalization hardware that is in the subwoofer out signal path of a pre/pro will be limited to treating frequencies below the low pass filter setting -- normally 80 Hz.
The Anti-Mode 8033 is a room mode correction system that operates in the subwoofer signal path. Even though it can operate up to 114 Hz (I think that's the spec), it probably won't see frequencies above 80 Hz, assuming that's the LPF setting you have set in the CXA-5000 pre/pro.
Hope this makes a little sense.
Now, another comment regarding your subwoofer placement. If I understand correctly, you have the left & right main speakers atop a pair of subwoofers. You have basically constructed a full range speaker, but unfortunately, you have removed one of the key advantages of using subwoofers. Sat/sub speaker systems have a key advantage over "full range" speakers in that the bass source can be placed independently of the mid/treble source. We usually place the main speakers where they provide the best imaging and sound staging. It is highly unlikely that that location will also yield the best bass response.
So I would suggest that you take a look at Tom Welti's "Subwoofers: Optimum Number and Locations" paper from Harman link above. Then consider decoupling your subs from your left & right speakers.
If you are really motivated, you can spend a little time measuring the bass response in your room. All it takes is an inexpensive SPL meter (Radio Shack analog meter will work) and a set of bass test tones (see the Real Traps web site).
I believe that Yamaha has their own room mode correction system (YPAO). I assume you are using that. If so, it begs the question, why the Anti-Mode 8033?
Thanks Bob. I really do appreciate the time and effort you put aside with your very comprehensive reply. Awesome. Thank you so much! and most informative.
Now I understand "room modes" a lot better.
I am using the the Anti Mode 8033 in tandem with the Yamaha YPOA for the following reasons Mr. Kalman Rubinson from Stereophile magazine mentions in the end of his review of the Yamaha CXA-5000 and he says this;
"A look at the graphic presentation of YPAO's correction results revealed all (fig.1). All of the correction filters were of low Q (ie, broad in frequency), and there was little correction in the low end. One of the L/C/R channels now had a filter at 63.1Hz, but the rest were at 78.7Hz or above. No filters below 125Hz were applied to the L/R surround channels, even though their placements in the room's corners subject them to a severe diagonal room mode near 45Hz. Nor were any filters applied to the subwoofers below 125Hz; with the Yamaha's bass management applied at 40Hz (fronts) and 80Hz (surrounds), this meant that YPAO was not applying EQ below 100Hz.
Even knowing that, and despite its lack of effect on the lows, I continued to prefer YPAO-Natural to Through (no EQ at all), for the former's natural-sounding mids and highs. YPAO has filters that can have their center frequency set as low as 31.3Hz, and a more-than-adequate range of gain and Q, so it could be used for the bassbut it seems that the correction algorithm made no use of these filters. This left me with three options: 1) I could use the RoomEQ Wizard, Omnimic, or XTZPro room-optimization software to measure and develop bass filters to add to YPAO's results; 2) I could add an external subwoofer equalizer; or 3) I could accept the Yamaha's settings and say that, although the Aventage CX-A5000 is an excellent, transparent, capable pre-pro, in this aspect it is flawed."
This is why I felt that the Anti-mode 8033 would go some way in solving the above shortcomings of the YPOA. It certainly seems effective..
There is only one more thing you mentioned Bob, that I do not fully understand, even after studying the Harman Kardon link. Why is it that you think that having my bookshelf speakers mounted on the subs is not ideal?
Is it that you think, (In layman's language) that the vibration from the subs might interfere with the sats?
Glad you read Stereophile and Kal's column. He has provided us with a wealth of equalization info in the past several years. So you picked his solution 2). Thanks for the clarification.
I'm suggesting that you could quite likely get a better bass response by placing the subs in different locations than you currently have them. It's generally suggested to get the best bass response you can via placement before utilizing equalization.
Tom Welti's paper showed sub locations that yield good bass response. I doubt that you would ever place your main speakers in those locations.
The main speakers and the subs should ideally be placed independently of each other.
Sorry I caused a detour in your thread and didn't address your question. Regarding bass traps, you might want to contact http://realtraps.com/.
I don't have any personal experience with their products, but I've always thought they provided a lot of good information.
I certainly did gets lots of good info.
I recently discovered that I had a few settings incorrect on my subs..
First of all- On my two front firing SVS Sub Ultra 13's, I discovered that before I ran the DS Peaker 8033 - I did not have the volume on the subs set to 2, like it said to do so in the instructions. There were a few other incorrect settings too and due to this the bass sounded bloated and not at all up to scratch. I spent about three hours carefully resetting everything one night last week. My conclusion is this - The DS PEAKER 8033 really works! Everything sounds so nice and tight now. I am really very happy with it all now. No need for bass traps and so on now, I am sure. The moral of the story is; when you get new gear, don't get too excited, take your time to set it all up. It will save you a great deal of disappointment in the end. Always take your time to read the instructions. Sometimes, isn't it great to state the obvious!