Subwoofer Isn't Making The Impact I Expected (1 Viewer)

[TommyL]

Matt..I'd email tom V directly...what are your room dimensions? I have to believe that anything under 2200 or so CF would be very obvious to bass in it...something just isn't right...I mean, I had a 2039 pci a while back, and I could hear it outside and down the road...so something is wrong...I currently have concrete all around me in a 4500 CF room...I don't believe that is the problem Email Tom/Ron...maybe, just maybe the amp is bad?? Try running avia sub test tones...actually..when doing the bass peak level, just try and get to +18 on it with the amp plugged in...if you can, and its not blistering your ears, something is wrong Let me know how it goes..I think we can help ya...I'll check back throughout the evening...but try these few ideas....the bass peak level at 0 will be hear biting..this will help us out. tom

 

[steve nn]

I agree. Something is amiss. If your mains are doing better for your LFE/Bass, then Huston has a problem. I wouldn't give up. Please get in touch with SVS. It could possibly be a faulty sub. Did you ever place the sub in a corner just to make sure even though it is not a long term option?

 

[MattCPT]

I did try the sub in the corner and the difference wasn't very noticeable. I don't want to give anyone the wrong impression, the PB-1 is definitely putting out a significant amount of bass. Increasing the "Bass Peak" level to +18 has increased the bass at a lower setting as I said before. I would consider myself fairly knowledgeable about setting up audio systems, but I must admit that I feel something is probably wrong. I would however think that if I can get 75db of bass from the sub at 1/4 volume then running it "hot" at over 1/2 volume should blow away my main speakers (with the receiver's bass setting at +5) but it doesn't. The difference is minimal. Both the PB-1 and my speakers are capable of shaking objects in the room when running AVIA's bass signal through them at high levels. This is what makes me think that I'm just getting better bass from my mains than I originally thought.

My living room is open to another room and staircase in the back. In all the two rooms are just about 4000 CF. The thing about my room is that the main speakers are to the sides of a built in entertainment system that extends 3 feet away from the back wall. This forms two boxes (minus one wall) where the main speakers sit. I think that this may be reinforcing the bass from the main speakers and limiting the bass from the subwoofer. The fact that my speakers are bi-polar (with speakers in the back) may also be adding to the impact of the bass that I get with my current set-up. This of course is all hypothetical.

I did contact SVS, told them my situation and requested information on returning the sub. They responded by saying that they would send me a return label. This may mean that they will pay my shipping, if so then I will be very impressed with their customer service. I would love to have kept the sub, after all I've spent a lot of time (too much according to my wife) researching the right sub for me. I just can't justify spending the money when I haven't heard or felt the type of bass that I feel others have. In all I am more satisfied with my current speakers (minus a sub) than I was before all this, so I'm not complaining.

Thanks again for all your help,

Matt

 

[TommyL]

75dbs?? hell, that thing should put out 105-110...I'm trying to recall my marantz more so now than ever before for ya. SO, bass peak level is @ +18..LFE is at 0...mains are set to small? Have you tried the internal calibrations in the 8200? Even though they may be off a bit from avia..I'd try them...I can't recall what my sub setting was, but I definatly knew when it was too much...Matt, when you do the sub tones only, what spl's are you hitting at your seat position? I would think 105 would be easy to get without breaking things....you have time to wait..go through these, and see if they help....tom (I'll check back)

 

[MattCPT]

Tommy,
I had only said that I can get to 75db with the AVIA because I was using 75db to calibrate all the speakers. The sub was capable of much more of course. My point was that I could get to 75db with the sub volume at 1/4 as opposed to 1/2 (as it was before increasing the bass peak setting of the 8200).

 

[steve nn]

Maybe this is one of those rare cases.:frowning: Sorry to here it didn't work out for you Matt. Your conclusion to the reason this is happening could be dead-on?? Can't argue with physics. It still seems very odd though.

 

[Parker Clack]

Matt:

What did Tom say about your situation? Did you tell him what is going on or did you just ask for a return label? I am like everyone else here in saying that something is not right. The sub should be blowing you out of the room and definitely be out performing your mains.

Parker

 

[TommyL]

Gotcha Matt Man, we need to fix it My mains couldn't keep up with my old sub let anone my new one...I'm thinking...check back tom

 

[TommyL]

One thing..I know that (if my memory serves me correctly) when you do the bass peak level, if you don't enter and exit out, it goes back to -72....This could be the case..I know, just like everyone says, they have done this...but it slipped through me also...trying our best for ya Matt tom

 

[MattCPT]

Thanks TommyL,
I did check and I'm at +18. Like I said, the sub seems to be working fine, the problem (if there is one) must be room acoustics. I have moved the sub now from the sidewall, to the corner and even in the center of the room (least effective of course). I can't get over the fact that both the sub and main speakers are producing what I feel is impressive bass when needed.

Is there any chance that my main speakers are just more capable than I had given them credit for?

I have gotten the bass loud enough on both the PB-1 and speakers that I have found the need to turn it down when watching a movie. This is what makes me think that the sub is working fine, but that the difference between my mains and the sub isn't as much as I thought. When doing the bass sweep with the AVAI I find that the sub can definitely reproduce more low bass at louder levels. However, when watching movies or listening to music DVDs I don't find a significant improvement in sound with the sub. In fact as I stated before, my wife and I find the music DVDs to sound better without the sub on.

I realize that my experiences are rare. I really wish that I had Ron and Tom or some of the HTF members available to come over and look at my calibrations and listen to my set-up to either confirm what I'm hearing or to show me where I may be going wrong. Of course that isn't realistic, but it would end my doubts.

Am I the only person to have these results when adding a sub?

 

[Zack_R]

Matt,

Your room conditions may give you some room gain at the seating postion which allows your mains (now that you've got the peak level boosted) to perform much better.

but when I read this;

When doing the bass sweep with the AVAI I find that the sub can definitely reproduce more low bass at louder levels. However, when watching movies or listening to music DVDs I don't find a significant improvement in sound with the sub.

I can't help but think that you have some speaker cancellation that results in poor sub response at your listening postion. I believe the Avia bass sweep is LFE only which means your mains produce no sound and therefore you get no cancellation. DVD music and movies can have combinations of LFE and low bass frequencies (crossed from your mains) that can / are creating bass cancellation at your seat. If you were not getting a strong response on the AVIA LFE sweep then I would say your room is more of the problem.

You also commented that with the sub on music sounded *thin*. This is an indication that the speakers and sub aren't cooperating with each other. Typical speaker / sub cancellation can greatly effect the common 60 - 90 hz music bass.

I had serious cancellation problems with my Ultra and 15" Acoustic Suspension floorstanders at the seating postion when I first set them up. The bass was tremdous if I stood right in front of the TV but was very thin 15 feet back at the seat. The SVS was located beside my right front speaker and that speaker turned out to be the culprit. I reversed the subs polarity and bingo the sound was now tremendous at the seat and thin one foot in front of the TV. Reversing the subs polarity had no ill effect on the left speaker. I went from a -5db sub output calibration to a -12.

Here is a way you can check the phase to see if one or both of your main speakers are creating a cancellation effect at the seat. Using your SPL meter and sitting in the listening postion, play the Avia subwoofer set-up that alternates between left-front and sub. Then play the alternating right-front and subwoofer portion. See if the spl meter indicates any differnce between the two tests. Then reverse the polarity (spin the phase dial to 180) and do the test again. I'm thinking that probably one of the mains are cancelling with the sub. If there is no difference then put the phase dial on 90 and re-test.

Even though you've moved the sub around you could be moving from one cancellation setting to another. Reversing the subs polarity to achieve a better result is not uncommon.

If your receiver allows you to select distance settings for your speakers ensure those are set correctly.

I know from my own trials that getting the sub to integrate the way you expect it should can be frustrating and tiring. The nice thing about a sub is that you can run your bass on the hot side and have it sound much better than if you were to just increase the bass level on your receiver with your mains only.

 

[TommyL]

What speakers do you have for mains? I just can't see them reproducing bassa t much under 30hz...I can see 40, but less shouldn't be close....unless you have some full range speakers...which we'll find out tom

 

[MattCPT]

TommyL,
As I stated previously my main speakers are Definitive Tech. BP-30. They are the largest of the Def Tech speakers without having a built in subwoofer. They are comprised of 4 drivers and two tweeters (bi-polar with 2 drivers and 1 tweeter on front and back). They stand 46 1/2 inches tall and 15 inches deep. They are rated down to 16 hz (no mention of SPL), but it would be safe to say that they are considered full range.

 

[Sheldon C]

Matt, what are the sensitivity of your mains? I ask because my mains have a sensitivity of 102 (cerwins, stop the laughter, I was young and didn't know any better). When I bought a svs 20-39 pci I didn't have the problems you are having, but I did notice that sometimes the sub sounded just a little strained (I run the sub around 8 to 10 db hot for movies which I know isn't the norm, but I like it).

Anyway, recently I experimented with using two rear center surrounds instead of the one rear center that my yamaha rxv3000 uses. To get enough volume for the two center rear speakers running off of one amp I had to change to setting for the mains that reduces their volume by 10 db. I wasn't all that impressed by the 2 rear centers as opposed to one but what I did notice was that while my mains were reduced by 10 db as well as all of the other speakers after adjusting them down, the sub output did not change.

The result was that I had to also turn down the level of the sub to match everything else. The sub no longer EVER sounds strained and I couldn't be happier, even though I was already happy with the svs. Now all I have to do is get some new speakers, and I'll be set.

However, my mains never ever came close to the bass output of my sub so that wouldn't explain why yours are... I don't know, just thought I'd throw in my 2 cents worth of attempted help...

 

[Matt_Doug]

Properly calculate phase by subtracting (the distance of the mains from the listening position) from (the distance of the sub from the listening position) and divide that number by (the speed of sound divided by the crossover frequency of the mains) and multiply the final reslult by 360. The result is the degrees you would turn the phase knob on the sub to.
If your mains are set to large then use the frequency at which your mains are down by -3db. this should make music sound better but if any explosive scenes from Pearl Harbor, Star Wars...etc doesn't bring your house down then something is wrong with your SVS or your system and its settings. I didnt see anyone mention to disable the crossover on the sub you might want to do that. Good luck.

 

[Tom Vodhanel]

Hi Matt,

I've sent off some thoughts in an email a couple days ago but haven't heard back. If you get a minute...I'll be looking for your reply, thanks.

TV

 

[Brian Fellmeth]

I've sent off some thoughts in an email a couple days ago but haven't heard back. If you get a minute...I'll be looking for your reply, thanks.

SVS must be the only company around where the owner is anxiously waiting to hear from a customer rather than the other way around.

 

[MattCPT]

I have my main speakers set to small when using the sub to avoid cancellation between the sub and mains. I also understand that this takes some strain off my receivers amp. My receiver sends everything under 80 Hz to my sub when the mains are set to small.

Tom,
I received your e-mail and plan on sending you a fax of my room. I will have access to a fax machine on Monday. I have played a little more with the sub this weekend but haven't found a difference.

 

[Tom Vodhanel]

Excellent Matt, thanks for the update.

Would you have much more placement flexibility if you had a much smaller subwoofer? If so, something like the sunfire sig or the HGS12 might ultimately be the best performance for you.

If you haven't boxed the SVS back up yet, try setting it to the same output levels as the rest of the speakers with a SPL meter. Now, place the SPL meter on the floor about 1m from the center of the unit. Pop in TPM DVD and run the THX intro at say....10dB under reference level and let me know what the meter peaks out at. (if you have time).

Tom V.
SVS

 

[Mark Zimmer]

Kind of along the same lines, I'm not feeling the same impact from my SVS 16PC46 I had when it was brand new, when it rattled my pants legs. Maybe I need to shut it off for a couple movies and get used to the missing bass and then put it back on to get that Whoa! feeling again.