Seaton Sound SubMersive1 - Page 253

Quote:

Originally Posted by nb67 

I’d like to give some feedback on Mark’s customer service. I ordered my second SubM and it arrived this Friday. UPS obviously had a field day using the box as a rubber bouncing ball. Anyway, the sub’s one corner was damaged which gives you an idea how they abused the box as the sub is extremely well packed. I emailed Mark Friday night and had a response Saturday morning assuring me that the next one is on its way come Monday morning. No hassles, no fuss. Now, if can persuade him to postpone the pickup so I can hear 3 Subm’s in my room…. bwwhahahaaa

I have posted on AVS & Mark's forum as to how well Mark has treated me. I just wish that he could find the time to post more often.
Lately we are lucky if there is more than one post on either AVS or his forum & then only starting mid week. (His range of knowledge
is exceptional)

Quote:

Originally Posted by Ashi777 

Hey guys,

Its been about a week since I've had my new submersive now. One word, Incredible. Its everything I was wanting in a sub. Clean, fast, low and bulletproof. However, lately I have been worried about possible structural damage to my house

The sub seriously shakes the house. The scene in the Dark Knight Rises, where the bat launches for the first time apparently had things shaking on the other side of the house. The walls rattle and everything. Me and my dad are worried about the structure inside of the walls coming loose, getting cracks and all. The house is brand new, it was just built last year. Half of the room is windows. (Obviously we didn't plan to keep a monster in there ) But I dont hear them rattling, mainly the walls on the other side.

So my question is should I be worried?

Could I get a bit of detail on the answers please.

Cheers guys!

Ashi - Hi.  You’ve already received some good advice but I'll add my comments to add some more perspective for you. I currently run TWO SubMs in a room of about 1000 cu ft - IOW a very, very small room. I generally listen to movies fairly loud: -7dB on the MV. Now while my subs sound and measure really really well (you can see my detailed report a page or two back, with graphs) they do not in any way endanger my house!

My first thought is that you have not calibrated your system, or not calibrated properly anyway. Unless you have either a) measuring gear like REW or OmniMic, or Audyssey or Anti-Mode or similar, it is very difficult to calibrate subs. Using an SPL meter and setting the sub to 75dB is usually not very accurate, as the meters do not perform well down to 10Hz or less (unlike the SUbM). So my bet is that you just have the sub set up WAY too loud. My subs are set (on their own gain controls) to almost OFF for example - they are about two clicks from OFF*.  How big is your listening room and how far do you sit from the speakers and/or sub?  What equipment do you have? Do you have measuring gear, Audyssey, AntiMode etc?  If you tell us what you have we can help you dial the sub in properly. Please see my detailed review for the procedure I had to do in order to get a nice flat response in my room. In the review you will see a remark about how I initially set the subs up (in excitement to hear them) and they did indeed shake the house. But the objective of a good sub is not to to shake and rattle your house.  What level do you have the sub gain control set to?

Please answer the questions in red above and tell us more about your room, your system etc. A couple of photos would be useful too if you can (cellphone photos are fine).  Don't worry - you will get this sorted with the help of this thread - but I bet if you could measure your response from 10Hz - 20kHz you would see a huge level boost from 30Hz down.

* Incidentally, setting the sub gain control very low doesn’t mean you are 'wasting' some of the sub as people sometimes think. It is a gain control not a volume control so what it does is control the incoming signal level that's all. Your sub will still deliver all of its power - just from a smaller input signal.

Quote:

Originally Posted by Ashi777 

Quote:

Originally Posted by Gary J 

I would be but I EQed mine so I am not.

Okay so could you please explain as to how EQing can prevent possible damage?

EQ isn’t the answer, although it's part of it (see my earlier reply). A system can be 100% properly EQd but if it is capable of playing a 10Hz tone at 115dB, it will still shake the house!  I don't usually 'see' Gary J's posts but he is famous for posting a few words that usually don't help anyone much. If he really means that EQ will stop your subs shaking the house, he is just wrong (as you seemed to know intuitively). You do need to EQ the system to get the flattest response you can, but even if it is EQd you can still shake the house if it will play very loud, very low, which is just what a SubM can do.

Quote:

Originally Posted by vardo 

Ashi77, you are running the sub level waaaay to high. Structural damage to the house?
I know it's great to hear and feel loud bass, but you have to blend the sound of the
subs with your mains. Otherwise, obviously, the sound coming out of your system
will be out of proportion, with the sub overpowering the mids and highs.
 

+1.

Quote:

You don't necessarily need an eq device. Use your EARS. 

vardo

It's true you don't necessarily need an EQ device or measuring gear but they do make the job so much easier. There aren't many (any?) big, powerful subs that don't benefit from a touch of EQ. Let's see what Ashi has got - he may have some measuring gear or EQ device already, in which case we can give him the heads-p on how to use it get a good flat response. But yeah, I agree - I'd bet they are just way too loud.

Quote:

Originally Posted by Ashi777 

Quote:

Originally Posted by vardo 

Ashi77, you are running the sub level waaaay to high. Structural damage to the house?
I know it's great to hear and feel loud bass, but you have to blend the sound of the
subs with your mains. Otherwise, obviously, the sound coming out of your system
will be out of proportion, with the sub overpowering the mids and highs.
You don't necessarily need an eq device. Use your EARS.
vardo

Hey there,

Thanks for the advice.

Well the bass isn't dominating any other frequencies. There's no problem there.

What I mean by structural damage is possible cracks in the walls or ceilings... Damage of that sort.

I do have a problem with the placement ATM. The sub is not placed in the optimum position right now. So I do have it a little higher then it needs to be because I can't hear it all.

I probably do need to EQ It because the room modes are horrible in that room.

I think you'll find the bass IS dominating the other frequencies, but maybe you have always run your subs hot and are used to it. Thing is, you can run a lesser sub hot and it won't shake the house simply because it has very little capability below 20Hz. But the SubM is a beast and can really dig low, and go loud.

Where is the sub placed and where do you sit in relation to it?  It is possible you are sitting in a huge null (20-30dB nulls are not uncommon). I know all about placement problems - goes with the territory for those of us with small rooms, but your room will be bigger than mine (I am sure!) and you’d be surprised how you actually do have placement options when your really try.

As you have already said the modes are horrible, how do you know?  Have you calculated them with one of the many online room mode calulators, or have you measured?  Like I say, sit in a 20-30dB null and you won't hear much bass - but the rest of the house will!  Have you done a sub crawl or just tried moving around the room with an SPL meter and (while playing a bass test tone) seeing what the variation in SPL is at different parts of the room?

Quote:

Originally Posted by craig john 

Quote:

Originally Posted by Ashi777 

Hey guys,
Its been about a week since I've had my new submersive now. One word, Incredible. Its everything I was wanting in a sub. Clean, fast, low and bulletproof. However, lately I have been worried about possible structural damage to my house
The sub seriously shakes the house. The scene in the Dark Knight Rises, where the bat launches for the first time apparently had things shaking on the other side of the house. The walls rattle and everything. Me and my dad are worried about the structure inside of the walls coming loose, getting cracks and all. The house is brand new, it was just built last year. Half of the room is windows. (Obviously we didn't plan to keep a monster in there ) But I dont hear them rattling, mainly the walls on the other side.
So my question is should I be worried?
Could I get a bit of detail on the answers please.
Cheers guys!

It is very important to properly calibrate your sub. Running it hot will exacerbate the transmission of sound to the structure of the house, and the louder you turn it up, the worse the problem will get.

However, in spite of what Gary J says, EQ is generally not a very effective tool for reducing sound transmission through solid materials. With EQ, you are as likely to boost problem frequencies as you are to cut them. In addition, if you use a lot of cuts with the EQ, you need to raise the overall volume to "normalize" the levels. If you want to use EQ to reduce sound transmission the way to do would be to go to the end of the house that vibrates and shakes and measure the frequency response with a spectrum analyzer. A house, like any other structure or material, will have a frequency at which it "resonates." This resonant frequency will be the loudest in that space. Once you've identified the problem frequency, go back to your system and use your EQ to cut that frequency. Of course, that frequency may not be a frequency you *want* to cut in your room. The resonant frequency of the house structure may or may not be a problem frequency for your in-room acoustics. The two are totally unrelated.

Other than that, there are only 2 effective methods for reducing sound transmission to the rest of the house structure:

1. De-couple the subwoofer from the structure with something like the Gramma or SubDude: http://www.auralex.com/sound_isolation_subdude/subdude.asp These types of devices reduce the mechanical coupling of the vibrations of the subwoofer cabinet to the floor. Of course, the Submersive, with its' dual opposed configuration, has an absolutely dead cabinet so there are no vibrations to reduce. The F2 *may* have some cabinet vibrations, but its' cabinet is said to be very dead. Either way, this type of de-coupling likely won't fix your problem.

2. De-couple the room from the rest of the house with sound isolation construction techniques, aka "soundproofing." Sound isolation uses "room-within-a-room" construction techniques to isolate the listening room from the rest of the house. Google "sound isolation" to see some of the products and techniques used for sound isolation. It is a whole science unto itself, and it has virtually no crossover into in-room acoustics. The techniques used to get flat in-room acoustics will have no impact on sound transmission.

Other than those techniques, you only have ONE tool you can use to reduce sound transmission to the rest of the house: The Master Volume Control.

Good luck.

Craig

Hi Craig - there's no disagreeing with any of that at all, but I'll put my money on Ashi simply having it cranked up way too far - possibly because he's sitting in a null and doesn't realise it, or possibly because he has always overcooked his bass a lot with his previous sub which wasn't capable of bringing the house down.  His symptoms are similar to the ones I had when I did a quick and dirty setup after the F2s arrived (impatience of course) and my whole house shook too. When I did a proper calibration later I realised that I was running the F2s about 10-12dB hot! And with Dynamic EQ adding Lord knows what to that as well! If Ashi can give us more info, and especially if has measuring capability, I am sure we can all help him dial in his sub properly.

It's fun to feel the house shake - but it gets old real fast and there's no substitution for proper, flat bass right across the frequency spectrum -  something we have all had to do some work to achieve.

I think that when one gets to the level of Submersives, it takes (and rewards) some effort to get them working to their best - look at Mike Duke's story for example - and my own. And yours too of course. None of us just plonked the sub down where it would fit and then got a great result first time - we all had to work at it and I suspect Ashi will have to do the same. The joy is that, when the work is done, he will have bass like he has never had before - and not just in terms of quantity but even more important, in terms of quality. 

Quote:

Originally Posted by craig john 

Hi Keith,

Ashi's question was about whether he needs to be concerned about structural damage to his home from the subwoofer. My post was in response to Gary J's contention that EQ can correct sound transmission problems. He has stated that belief before in other threads. When I've asked him to explain how it works, he gets offended. He has never explained it. Therefore, I felt it was appropriate to explain to Ashi, (who seemed to believe Gary), why it can't and doesn't work.

I think Gary is lumping level calibration in with room correction/equalization. Audyssey does both in the same process, so he probably thinks they are the same thing. They are not. Level calibration can help with sound transmission, especially if the sub is set "hot". However, it can only help up to a point; that point being the setting of the Master Volume Control.

Room Correction/equalization can't help with sound transmission, unless you get very lucky and the problem frequencies for sound transmission align exactly with the problem frequencies for frequency response at the listening position AND the EQ doesn't use any boosts, only cuts. Sound "coupling" to the walls, floor and ceiling occurs at the interface of the air with the structure. The air pushes and pulls on the structure and "excites" it to vibrate. This happens at the *wall*, not at the listening position. The frequency response at the LP is immaterial to the coupling of the air to the structure at the *wall*.

The only way to prevent sound transmission is to use sound isolation/soundproofing techniques. If Ashi's concern is eliminating vibration in the rest of the house, sound isolation/soundproofing is the best way to get there. Other than that, level control is the only other tool, either with proper calibration or judicious use of the MVC, or both.

Craig

Hi Craig - yes, I wasn't disagreeing with you - I was just adding my view that if Ashi is unknowingly running 15dB hot (maybe because he is sitting in a null) then he is sure to be shaking his house. If this is the case, chances are when he calibrates to a correct level, the shaking will go away. It's exactly what I found when doing the Q&D setup of my F2s.

EDIT: we are both definitely in agreement that EQ cannot fix sound transmission problems.