There is know reason to be Steve. You have a Kick A$$ setup
Now I KNOW you're
[Show spoiler]But thanks - It Does sound great for MY set-up/room size, & my 2 PA-120 Subs (with One DIY Riser) [<--- On TOPIC!] Thump when called upon
I have pretty clean bass as is with my two down-firing Polk DSW PRO 500's using an AntiMode 8033 bass equalizer; but this topic seems interesting and I'm all for experimenting to get better sound. With a cathedral ceiling should I just approximate the ceiling height at 9-1/2' for an 11' peak with 8' walls and build a riser to that? crazyBLUE, I like your design and am thinking of something similar. Here's what I just put together in MS Paint (not to scale):
I'm going to need to get longer cables for the subs now...
And power cords will need to be longer too - doah!
I have pretty clean bass as is with my two down-firing Polk DSW PRO 500's using an AntiMode 8033 bass equalizer; but this topic seems interesting and I'm all for experimenting to get better sound. With a cathedral ceiling should I just approximate the ceiling height at 9-1/2' for an 11' peak with 8' walls and build a riser to that? crazyBLUE, I like your design and am thinking of something similar. Here's what I just put together in MS Paint (not to scale):
I'm going to need to get longer cables for the subs now...
And power cords will need to be longer too - doah!
Vracer.
I guess to start off I did not built any of the risers I have made to a specific height as to how tall the room is. I Built them to get them off the ground & found that having the subwoofer higher up was better at least in my room. Remember I am crazy & didn't go by a certain height as for how tall my room is
One thing I would recommend with the drawing you drew in your post is to make sure the subwoofer is not going to fall off the riser that you make it sturdy & safe to be around.
I like the idea you have drawn up Just make sure on a big rumble the sub isn't going to come down.
I have pretty clean bass as is with my two down-firing Polk DSW PRO 500's using an AntiMode 8033 bass equalizer; but this topic seems interesting and I'm all for experimenting to get better sound. With a cathedral ceiling should I just approximate the ceiling height at 9-1/2' for an 11' peak with 8' walls and build a riser to that? crazyBLUE, I like your design and am thinking of something similar. Here's what I just put together in MS Paint (not to scale):
I'm going to need to get longer cables for the subs now...
And power cords will need to be longer too - doah!
I like your design and good luck to you.
Just remember that Home Theater is not an exact science. Most of the rules are approximation rules in order to achieve marginally better sound.
As I said before, the pressure zones (room modes) are spread out and not pinpoint-sized. For all practical purposes, the subwoofer should be located at least 25 percent away from the boundaries to best avoid stimulating any of its first three harmonics. There is no location towards the middle of the room that suits a subwoofer position, as the pressure zones there are overlapping.
Crazy, you wouldn't happen to have any before/after graphs or measurements from REW or RTA would you?
I've been looking at the ACS website and the graph they provide for the subtrap doesn't seem all that great to me:
It looks like nothing much is happening until 55Hz to 100Hz (I assume up to 120HZ if you crossover is set that high)
I see only a 2db improvement at 55-80Hz. Then maybe 8db at the 85hz crossover.
Now I realize a LOG SPL graph may not be showing the all the benefits. But that's why I keep askin for hard data!
Or, at least how to capture it.
Very cool thread.
Test,
Although a frequency response is important and demonstrates part of the overall performance of a speaker or subwoofer, it does not show how they sound in a particular room. Otherwise, when you plan to buy a speaker or a subwoofer, you should completely ignore speaker auditioning and just rely on their published frequency response curves. Generally speaking, speakers with the same frequency response curves do not always sound the same.
Although most people tend to set the crossover frequencies in the 80Hz-100Hz range, there may be significant output in the LFE channel of 5.1 and 7.1 movies up to 120Hz.
Overtones & Undertones: All tones when produced excite other, different tones that vibrate along with them. Every sound consists of the actual sound that is produced, called the fundamental, as well as the overtones and undertones. The number of overtones and undertones and their loudness, relative to the fundamental, determines the character of a sound. These overtones and undertones are generally referred to as harmonics. Those other sounds, the harmonics, may be louder or softer in volume or greater or lesser in quantity.
When sounds are recorded and played back, all the sounds that emanate from the loudspeaker become fundamentals, even those that are the overtones and undertones of the sounds that were recorded. This means that they all produce their own set of harmonics. The result is a massing of these over/undertones.
On the subject of Placebo. It is true that placebo is a powerful factor and can completely bias our judgement, but we cannot blame placebo for the effect of any change that we can hear. Our ears, despite of their many flaws, can tell the effect of many changes that are not necessarily due to placebo. When we go to audition speakers and subwoofers, we prefer one brand over another, even when they all have perfectly flat frequency response. I have attended many audio shows and could easily tell the difference between the ultra high-end speakers that were totally beyond my budget, even if on paper they had similar frequency response curves. I also have a closet full of cheap and expensive gadgets that I have bought over the years with the hope that they would improve the sound in my system. In some cases, I really wanted to hear the difference and justify the expense, but at the end of the day, I had to be honest and admit that there was no benefit and that is the reason they are sitting in my closet picking up dust.
I have to disagree with your comment about the unimpressive performance of the Subtrap. If you go back to my previous post # 1754, you will remember that in a typical room with a ceiling height of approximately 8 feet, the room modes occur at 70.6Hz and 141.0Hz. It is not surprising that the frequency response curves with and without the subtrap show the most significant changes in the upper bass frequencies. In my opinion, the subtrap is doing the job that it claims it can.
You should not just bring a graph from a review and make conclusions. It is a bit out of context. You should look at the general review, different graphs, tables, comments, and conclusions. Here are some of the other comments the reviewer made from the same article you took the graph.
RT/30: This test measures the amount of time it takes for select frequencies to drop in amplitude by 30 dB after the test signal terminates. As shown in the table below, the ASC SubTrap significantly reduced the RT/30 times in the 40 Hz - 60 Hz bandwidth. I was particularly impressed with the nearly 400 ms RT/30 reduction at 50 Hz. Be careful not to misinterpret the test result at 80 Hz. Because the SubTrap eliminated some nulls in the 65 Hz - 90 Hz bandwidth, the frequency response in this region has more inherent acoustic energy with the SubTrap in place, so the RT/30 times will be higher.
Buzz/Rattle Test: I ran a slow reverse sine sweep (120-20 Hz over 45 seconds) through the subwoofer, listening for buzz and rattle in the evaluation room. Adding the SubTrap without question reduced the quantity and magnitude of buzz and rattle in the room. This is a result of both the isolation platform reducing vibration transmission through the floor, and also the bass trap reducing excessive reverberant bass energy in the room.
Listening: My subjective impression is that the SubTrap provides a more cohesive and coherent sonic presentation, with less boom and overhang. The bass quality is more ethereal, seeming to emanate directly from the soundstage, rather than the subwoofer itself. Part of this improvement could be due to the SubTrap elevating the subwoofer and placing it closer to the main speakers, creating more of a point source.
While the SubTrap obviously cannot increase deep extension, the trapping of excessive reverberant mid-bass energy allows the listener to hear the deepest bass with more clarity, thus improving the perception of deep extension.
Conclusions
The ASC SubTrap works as advertised. It reduces vibration transmission through the floor, improves the frequency response in the mid and upper bass regions, reduces low frequency reverberant decay times, and it locates the subwoofer closer to the height of the main speakers. Not surprisingly, this unique combination of engineered performance features results in an audible improvement in the bass quality. Discerning HT and hi-fi enthusiasts will definitely appreciate how the ASC SubTrap extracts the best possible performance from any subwoofer.
Finally, take a look at what filters Meridian Room Correction (MRC) created for this review subwoofer. The table below demonstrates the characteristics of the filters required to correct both floor and on-stand performance. In this table, green indicates a decrease in filter requirements, and red indicates an increase in filter requirements while the review sample is placed on the subwoofer stand. It is quite important to note that while some individual frequency filter characteristics are slightly worsened, the aggregate performance is dramatically improved. In the case of filter gain, the variation between largest and smallest filter is just 2.5 dB, and in the case of RT-60, the variance is down to just .053 seconds. So, even without MRC to assist, the overall performance is demonstrably improved.
Conclusion
This review is a bit of a departure for me, since I usually spend a fair amount of space talking about subjective impressions of audio fidelity. I spent very little in this review discussing the audible benefits. That doesn’t mean I’m unimpressed, since this is hardly the case.
I’ll put it to you this way, the ASC SubTrap made a marked difference in the bass reproduction in my reference room, and I’ve got the measurements to prove it! Bass articulation was dramatically improved, and the little bit of boominess I heard prior to its use was eliminated. Some very familiar passages that were slightly problematic were
now presented with a clarity that I was quite pleased with.
ASC will not be getting the SubTraps back, as I now consider them to be an indispensable part of my review system––and Art, as the cliché says, the check to pay for these is in the mail!
In conclusion, you need to consider many factors in order to get the best possible bass response in your room. Some of these are as follows:
Quality of the cabinet, driver, and amplifier.
Polyfill and dampening.
The room and the placement of a single subwoofer. Each room is different and what works in one room may not give you the same results in another room.
Room treatment and bass traps.
At best, a single subwoofer may give you good bass response for only one listening location.
The need for multiple subwoofers.
Risers. Their benefits are:
Isolation and decoupling from the floor.
Dealing with vertical axial modes. To be effective, they need to be of approximately specific heights.
Act as a bass trap. To be effective, they need to be tall enough and filled with bass trap material.
Equalization. It is the last resort in improving the bass response. It is much easier to reduce a frequency peak than fill a bass hole.
It is important to note that none of the tweaks will give you a night-and-day improvement. At best, you may get a marginal improvement. However, if you pay attention to all of the above, you will hopefully achieve a significant improvement in your overall bass response.
Home Theater is not a science class and meant to be enjoyed by people. Let’s not ruin their fun by diverting too much attention to factors that the majority of people do not understand or care about. Most people are happy with their HTIB, boom boxes, and simple 5.1 setups. That is what home theater is meant to be. As long as they are happy, all power to them.
I'm certainly not trying to ruin anyone's fun! Thats for sure.
I'm just really interested in the real world (everyone's room, my room) measurements and be able to correlate "What we Hear" over top of what the measurements actually say is happening in our respective rooms.
Forget the ACS subtrap. Most in this thread have reported benefits building their own risers that probably do not even come close to the technology of the ACS Subtrap.
The RT-30 and RT-60 measurements are pretty exciting. Thats the kind of data I'd like be able to show.
My own graphs (waterfalls,SPL ,Spectral Decay graphs) really didn't show any kind of improvement with my particular risers and I was surprised because I DID hear a difference (or did I?....lol).
For example: These are the latest measurement I recorded.
Do my graphs show any benefit using my risers?
I'll keep learning and keep testing. I'm used to being humbled so I'm not worried about making mistakes. I know I'll be call out for them and that's fine by me.
Your frequency response graphs certainly demonstrate that the two risers in your room have some effect. You should not expect any change in the lower frequencies. Most of the effect of the riser will be in the upper bass frequencies That is where the vertical room modes are.
Also, your waterfall graphs show a noticeable reduction in the reverberant decay times in the 100Hz+ region and that is a positive benefit.
Your frequency response graphs certainly demonstrate that the two risers in your room have some effect. You should not expect any change in the lower frequencies. Most of the effect of the riser will be in the upper bass frequencies That is where the vertical room modes are.
Also, your waterfall graphs show a noticeable reduction in the reverberant decay times in the 100Hz+ region and that is a positive benefit.
Ok now were getting somewhere. I wasn't really looking for 80hz - 120Hz benefits. When you think of LFE ,80hz and below is where you tend to look.
(For an inexperienced guy like me that is)
This is the kind of feedback that I was hoping for Big Daddy. Thanks!
I'd still love to see others here post some results if they can. This is so interesting.
Test,
Last edited by Test4echo101; 08-04-2011 at 08:20 PM.
Question - will a foam pad that you would use to sleep on when camping, work for filling up the bottom of a riser? I used that to pack my old speakers for shipping and have some left over (2" and 3" high foam)- enough to fill one riser. I'm gonna build a pair of 17" x 9" riser boxes. Also, will I need to fill the empty void with foam completely?
Question - will a foam pad that you would use to sleep on when camping, work for filling up the bottom of a riser? I used that to pack my old speakers for shipping and have some left over (2" and 3" high foam)- enough to fill one riser. I'm gonna build a pair of 17" x 9" riser boxes. Also, will I need to fill the empty void with foam completely?
Yes, you can use it. Any kind of foam should dampen the area under the riser and absorb any noises that may come out of the subwoofer's port or other sources. Foams can absorb higher frequencies and are ineffective in dealing with lower frequencies. If you build a riser that is tall and you want it to act as a bass trap at the same time as a riser, you need to use rigid fiberglass or mineral wool. Of course, that makes the riser too expensive and in some situations more expensive than the subwoofer.
It is perhaps a good option for a person who wants to build DIY bass traps and uses the extra material under the riser. The cheapest place to buy rigid fiberglass or mineral wool in small quantities is ATS.
1)Hey guys, are there any stores that are pretty common in the U.S.A. that carry acoustic foam for the bottom of my DIY subwoofer riser?
2)Also, when I make a subwoofer riser, should i put a little carpet/carpeted mat/rug underneath riser as well?
3)How much (many inches) of acoustic foam should I put on the bottom?
Thanks!
thanks zippo, but I'm trying to get it from a b&m store. Would polyfill work? Im pretty lost on exactly what type or brand of foam to buy...high density foam?
Last edited by test123455; 08-21-2011 at 09:19 PM.
I am re-adjusting the sub's crossover, and volume settings. Definitely notice the difference in the floor. The floor used to vibrate with loud bass -- an irritant to our house "condo" neighbors below. I really don't want them to complain about house-shaking bass, so these SubDude's are awesome! Now the bass kicks, but the house isn't "kicked" LOL
I'll let you know when I get it working at an optimum level. Want that tight-bass response, we all love so much
REALLY LOVIN' THEM RISERS!!!
Had them now for a while, and I seriously cannot imagine Home Theater life without them! They are tremendous in preventing low-level sound transfer to our house. My neighbor hasn't complained once since I installed them. And they still make our Home Theater look sexy!
Had them now for a while, and I seriously cannot imagine Home Theater life without them! They are tremendous in preventing low-level sound transfer to our house. My neighbor hasn't complained once since I installed them. And they still make our Home Theater look sexy!
Vary nice clean looking Home Theater DarkDune. Beautiful setup & glad the neighbor has stopped complaining
Color me disappointed. I finally got around to building my DIY risers today, using 3/4" MDF and 4" pine, stuffed with 3"-4" of foam. The positive - I'm getting as much bass output with my receiver set to "yes" for a subwoofer, than I was having it set to "plus". The negative - the risers did ABSOLUTELY NOTHING as far as room vibrations. I used Transformers and the "Ironhide sweep" scene as a test - yep, still there in it's all-so-irritating glory. I didn't even dare to try War of the Worlds because the bass is even worse on that film. At least I only flushed $20 down the drain, instead of $100.
I doubt it's the difference maker, but the top isn't covered yet, it's just bare wood. There's no point in covering it if the risers don't work...
I doubt it's the difference maker, but the top isn't covered yet, it's just bare wood. There's no point in covering it if the risers don't work...
I would def cover the wood with some carpet (maybe padding under if you can), then see what happens. If the Sub is just resting on a Hard surface, there's nothing to be Absorbed; hence, Vibrations. Don't give up yet!
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that you make it sturdy & safe to be around. 
I finally got around to building my DIY 
Linear Mode
