Axiom Home Page Forums General Discussion Advice from Axiom Owners Sub boomy? What to do?

Hope this is the correct forum to place this. I’m posting this in hopes that it may save someone else, what little of their sanity they have left.

I've been loving my M22, VP150 & QS4's but was some what frazzled about my sub being boomy. First let me explain, I'm a bass player and have been for 30+ years and as a result I am very finicky about my low end. I’m not an expert and don’t pretend to be but I know what sounds right, meters and charts help but in the end, it’s up to your ears to decide. My sub is a Velodyne CHT12, 12” front firing and ported on the front. It’s always performed well with my old Klipsch KG5.2’s, which I have retired to the music room. The home theater is in a 13x18x8 tile floor room with real plaster walls & ceilings. Pics can be found here. I use to have the crossover set to 40hz and never looked back. Well after much testing I was getting almost angry at the fact that this sub just sounded to boomy crossed over at 80 and 100hz.

So I started to shop around, of course HSU and SVS were on the list but I was really after a REL or one of the Velodyne DD series. The REL was out of my price range, just couldn’t justify that kind of cash. So I was thinking Velodyne but why would I want a Velodyne to replace a Velodyne? So this is were I spent well over a month testing different locations, even tried crawling around on my hands and knees, every configuration known to man, I tried everything. I did as much research as I ever want to do on this particular topic and thanks to all the sound tests, there a few movies which I probably will never watch again, lol. I even tried damping the box, bass traps (home made) to no avail. Then I ran across a research paper on vertical vs. horizontal acoustics, sorry, I don’t remember where I it was on the net. Surely this couldn’t be the problem, could it? My sub sounded fine until I increased the crossover with the smaller M22’s but it’s a Velodyne, they have a reputation for a reason and this sub was going to work come hell or high water!

I ran out to my storage shed and found some packing foam that came with a Whirlpool A/C. It’s not styrofoam, it’s almost material like in texture but yet it’s still a very rigid foam. It’s kind of like the foam that comes with the Axioms but it’s much denser. Two pieces combined were 8 inches thick and 6 inches overall wider than my sub. So I shoved the foam under the sub, effectively elevating the sub 8 inches off the floor and giving the sub a solid foundation of this foam material. Again, it’s dense, so dense in fact that the sub has barely put a dent in it. I do not have any type of graph to prove my findings, the only thing I have are my ears, the boominess, is gone! My sub has never sounded so good! It’s tight and so accurate now, even better than before the Axioms. It even sounds good crossed over at 120hz but I set it to 80hz for movies and 100hz for DTV XM radio.

An added perk of this saga for me is I was always cynical about user reviews of audio equipment, what gauge wire, equal length of runs, power source, etc… Now when I see a review ripping apart a product, I’m 100% sure that the person is a moron and doesn’t know what the hell they’re doing or they just don’t have the patience to troubleshoot, no, they’re just a moron.

I really hope this helps someone else because I was honestly ready to throw away 1k on another sub and possibly never look at another Velodyne, thank god I’m stubborn.

Interesting. There is a commercial product (the "SubDude") which seems to be intended for the same purpose, but I didn't think it would have that much effect.

This should get some people thinking. I would think about it myself except I'm really tired and have to get up in a few hours...

Abyss, nice setup by the way.

You sound like you covered all your bases. Boomy sub sound can be caused by a number of factors. Location, Sub Volume, Receiver level dB setting, phase/trim settings, etc... Did you calibrate your system using a SPL meter or pink noises tests. I'm glad you are able to get the sound you desire with this foam material, heck that is what DIY is all about.

If you like deep bass man, you should try to save up for a EP500, there is nothing like them in my opinion, Axiom is truely setting new standards with the 500/600 DSP controlled subs. And they go Lowwwwwwwwwwww

@bridgman, that SubDude sounds like it’s specifically designed as an anti vibration device. It doesn’t look like it would raise the sub high enough to alter the sound plane, at least from what I read in that white paper on horizontal vs. vertical acoustics.

@ sirquack, Thanks I covered almost every possible angle, that’s why I was getting so frustrated. My wife would walk by and just shake her head and I would get the occasional “not again” remark from her. I don’t have a SPL meter but my bud does and the last time he came over with the meter, which would have made 3 times in a month, he just said he wasn’t coming back because I didn’t need it. I was so close to the spl on all speakers including the sub that he said I didn’t need him or the meter, lol. My wife and friends always comment on my hearing, saying things like I must have been a dog in a previous life. I may eventually opt for a 500 or 600 or maybe a SVS or even a HSU but not before I demo the Def Tech SuperCube I or II next summer.

Abyss:

Nice post. That is an example I was looking forward to ask if someone have done it. I was wondering about raising the sub a little some time ago, when I read in some post of someone that did it with success (sure if it was posted here at Axiom or somewhere else). I even got some MDF to make a base, but I havent got the time to cut it and shape it.

Thanks to your post, I will try to retry that quest of raising the sub in a nice MDF base. When I was "crawling" to find the best spot, I did find that when I lifted the front of the sub only with some material,and the sound actually improved (boomyness reduced). Actually I ran the sub with the front pointing upwards for a while (about 6in in the front, 2in on the back), but it was not as nice looking. Also when I located the sub in the listening position (I mean, exactly in my couch), the boomyness was reduced. What it did not happen very well, is that the spot I found when having the sub in the listening position, was not the best to put the sub into, so the sub is located somewhere more suitable for the task.

Sub location is critical, and extremely dependent of the room. That can not be stressed enough. There is a lot of cases in this forum about it. I learn that the heavy way that involves lifting the EP500 all around the living room!!!

In a side note, I do agree that ripping off a product without troubleshooting is just moronic. Troubleshooting and getting the best out of a product is part of the expertise a good reviewer should have.

For example, I had a lot of trouble getting the EP500 to work in my room, but I knew that before even buying the sub, and I had crawl, meter, lift, move, crawl again, and meter again in order to get the best out of it... and let me tell you, it have been a nice experience for me that never did it before, and the EP500 is just a super performer and the envy of my colleagues. I would never complain in this forum (or anywhere else) about the sub not sounding the way I thought as soon I opened the box. It took a good amount of my inexperienced and limited time to get it the way its now, and I am thinking of getting the 2nd in the next quarter, after a post that a member of this forum linked to a paper by Floyd E. Toole about running multisubs. (sorry, but I dont remember who wrote the link in the post)

And this forum is packed with knowledgeable people always willing to help non-experts like me on the setup of the equipment, and the search feature of the forum is really good.

It will be nice to read that paper you mentioned in acoustics. If you happen to remember the link, you can post it here at the board.

Regards

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after a post that a member of this forum linked to a paper by Floyd E. Toole about running multisubs. (sorry, but I dont remember who wrote the link in the post)

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That'd be me, I think.


Sutter

Abyss,

Have you tried the "sub crawl?" This entails placing your sub at your prime listening location (move your chair/couch!) then basically crawling around listening to your reference music until it sounds right. Super low-tech, using only your Mark-1 Organic Listening Devices. But it can really help.

Ah, those poor folks who have to lug around their massive box subwoofers, they should have bought the Hsu TN-1220HO, which goes down to 20 Hz and weighs only 30 lbs. (The 500W amp is in a separate unit, and the cylindrical design apparently doesn't need as sturdy a frame as box.)

Thus cylindrical subs can be better for your health.

--Martin

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So this is were I spent well over a month testing different locations, even tried crawling around on my hands and knees, every configuration known to man, I tried everything.

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Yep, he sure did.

@aabouganem, no, I’m sorry, I don’t have a link but I will try to find it again when I have time. It was a desperation move on my part. I read the article by a so called acoustical engineer and thought “yeah, right, whatever, I’ll give it a shot”. I would have tried snake oil at that point, so I closed my browser and went on my way with the already preconceived notion that it was not going work so I did not think to bookmark the link.

@LightninJoe, of course, I mentioned that in my first post. In fact I put it off for a while because I already had my sub in a place where it had been perfect before and that’s right where it wound up again. Like I said I’m not an expert but I’m certainly not your average user.

@nitram, a Def Tech SuperCube II has 1250 watts DD amp and weighs only 38lbs and goes down to 14hz Not to mention SVS make non powered subs as well but why would I want a monolith the HSU TN when there are much better solutions for my needs and tastes? Plus I’m 6’5” and 250lbs so when the day comes I can’t toss around a little 100lb sub I’ll sell off my equipment and get a boom box