Subwoofer Location

Hello,
I’m new to this forum but I’ve dabbled in car/home audio for a while. My home system is as follows:
· Onkyo M501 amp
· Onkyo receiver
· Vector Research satellite array
· Sony big screen / DVD player
My interests are:
· Rock, grunge, pop, oldies
· Home theater
My budget-minded goals in order are as follows:
· Construct a subwoofer to supplement music and video
· Add a A/V surround sound receiver (considerable latter)
My question regards the subwoofer. I need to settle on a location then select what subwoofer amplifier to purchase. Please view these possible location pictures:

http://members.cts.com/funtv/c/core/sub/sub1.jpg - Location just left of TV under vase with driver firing left or right but I don’t like the idea of aiming right towards the TV (6.4 cubic ft)

http://members.cts.com/funtv/c/core/sub/sub2.jpg - Location under A/V rack with driver firing right (2.6 cubic ft)

http://members.cts.com/funtv/c/core/sub/sub3.jpg - Location above TV with driver firing up

Note that the wife will not allow me install a speaker grill that can be see on the front wall on the entertainment center, only to the sides.

I plan on constructing a custom sealed box that will fit in one of these cavities and simply installing a grill on the drywall directly if front of the driver.

Any thought on the best location/plan?

I am entertaining the thought of purchasing a PE 250W at 4 ohms plate amp (current on sale for $118) from PE along with either the 12” Dayton titanic MK II or the 12” Shiva MK III from acoustic-visions ($125 shipped). I’m willing to spend 300-$400 for components and I’m open to suggestions.

Any thoughts on the amp or the sub?

Thanks in advance.
 
Be wary of siting the sub near the CRT or it may go rainbow on you.

The way a sub excites resonant modes is very room dependent. I would suggest building a box you can move around (if if only a temp box) until you find the best place.

besides the Daytons & Shivas (which are fine woofs) there are a large number of other competitors worth looking at. I just got 2 Stryke/lambda SAE 1024s which i am particularily enamoured of... the pictures don't do these beauties justice.

dave
 
Re: Re: Subwoofer Location

planet10 said:
Be wary of siting the sub near the CRT or it may go rainbow on you.
His tv looks like a projection type... does anybody know how strong a mag field would have to be to cause a problem?

It looks like a nightmare room, made worse by the wife-imposed restrictions. Is a wife upgrade a possibility? :p That might blow your budget... better to stick stick with the original plans, I think.

I am not yet married, but my girlfriend doesn't mind(or at least pretends not to) huge TVs and speakers. It's a tough enough situation to build a system without any constraints, so I wish you the best of luck. You'll find something you'll be happy with, I'm sure.
 
Re: Re: Subwoofer Location

planet10 said:
Stryke/lambda SAE 1024s which i am particularily enamoured of...
dave

Dave,
I am most defiantly open to using another subwoofer and/or amp. Can you elaborate on what you like so much about the SAE1204’s. What type of enclosure are you using?

Also the TV is a rear projector but I’ll test the raw driver near it just in case once I get it (TV has 3 small picture tubs in the front that can be effected).

Thanks,
John
:)
 
Re: Re: Re: Subwoofer Location

core said:
I am most defiantly open to using another subwoofer and/or amp. Can you elaborate on what you like so much about the SAE1204’s. What type of enclosure are you using?

From the front there is not alot to tell it from a Shiva or a Titanic, but turn it around and the gorgeous cast AL frame sets it apart. I also really respect Nick (of Lambda) and the quality of product he is producing -- the SAE 1024 is his bottom of the line. And it is also 1 for $110, 2 for $200 so it is less expensive then most.

I'll be doing a push-push TL with them. I just happen to have a split level along the front wall my living/listening room. The enclosure will be mounted in the ceiling of my shop (12' high) and load into the LR thru the wall.

dave
 
!!got the project just for you!!

I have just the project for you…
I have been hear for a wile and I have designed a few subwoofers for my home theater. The sub I am about to suggest is self designed and Sounds great. If you are interested I can give you a parts list and blue prints… This sub rocks the house. It is driven by a very nice sub by BLAUNKT. The sub is the Pcwi1200 and it puts out tight clear bass. It is also cheap…about $85 USD! The whole project will cost you less then $400 and is really is a great sub for the price… It’s detentions are 16” wide, 19” tall, and 21” deep. I run it at about 30% volume and it shakes the frames on the walls all over the house.
It is also easy to build and you don’t have to mess with XO because it is built into the PE 250w plate amp.

If you are interested just say so and I will draw up some diagrams…

Later,
Slice
 
What are the criteria?

I've struggled with the "sub problem" in a couple of houses, condos and apartments. [Two spouses(not simultaneously!), too.]

If pysical unobtrusiveness is the key element, the Sunfire Jr. beats out everything except something you build into the walls. Doing without, is not an option, I assume. The tube shaped subs from fom Hsu have a very small foot print but are very visible normally. The Newton Series from Cambridge Sound Works look like furniture. Put a vase with flowers on top and they disappear.

If sonics are the issue, it gets even sadder sometimes. The best location will almost always be blocking a doorway or some other unacceptable arrangement. They photos were nice but, I've found rooms to be so different from one another, the optimum location can't be decerned from a floor plan unless you put the room into an expensive 3D CAD file and run heavy duty simulations. The only thing that has worked for me is a combination of accoustic treatment and and professional audiospectrum aanalyzer I got on Ebay. My personal and biased opinion is that the choice of sub is not critical - choose it on the basis of budget, visual acceptability and footprint so log as it is from a respectable manufacturer. My rational is that location, accoustic properties of the room and practicality of acoustic treatment overwhelm mearly all the diferences in measured specs. The subjective desires like "tightness", "slam" etc have more to do with the room than the choice of sub so long as you avoid the few really terrible units.
 
Re: What are the criteria?

sam9 said:
[Two spouses(not simultaneously!)]

Too bad -- that could have been fun :^)

My personal and biased opinion is that the choice of sub is not critical - choose it on the basis of budget, visual acceptability and footprint so log as it is from a respectable manufacturer. My rational is that location, accoustic properties of the room and practicality of acoustic treatment overwhelm mearly all the diferences in measured specs. The subjective desires like "tightness", "slam" etc have more to do with the room than the choice of sub so long as you avoid the few really terrible units.

I have not seen it put this way before, but it closely coincides with my take on subs. There are so many good competitive drivers in this mid budget range that picking the driver is the least of your worries.

dave
 
That's Right

Don't ask me the physics of it, but it's supossed to be the case. It's called resonance respricosity or something. With the sub where you will listen, the loudest spot in the room will be the place where if you move thwe sub there that will be the location that gives your listening position the loudest level. Only glitch- loudest may not be the best since you are trying to blend in the sub with the other speakers. However, it is worthwhile undertaking to at least get started.
 
e96mlo said:
I have heard that you should place the sub at your listening position and then walk around and listen. The place where it sounds loudest is where you finally should have the sub.

Any comments on this?

/Marcus

Sure, if you can get a computer to simulate what will happen acoustically you are saving a lot of time. For Engineers and alike you also go for the numbers, proving that your placement works-and not relying on your ears. If I'm setting up a system for myself well, fire up my test CDs or DVDs and listen away! If anyone can find such software than please tell me.

I do know that if you are trying to 'blend' in the sub with the mid/high freqs. then placing the subwoofer above the mid/high freq. devices will do the job. There are more probs. associated with this though, such as resonance that carries into other rooms because the ceiling in your target room travels through doorways and in between walls unless acoustic dampening is used (doubt wife will like that :( . I also know that THX calls for the sub to be placed up front and away from corners so that the bass is still powerful yet, is more articulated than if it were in a corner. If your seating is close enough, I'd go with any side of the wall because low-freqs are omni-directional. And, yes it does get louder in some spots. Essentially, this louder effect is lessened once your sub is placed up front. My sub is up front and beside the left speaker, with proper volume adjustment and cross over adjustment the sound volume is pretty darn even.
 
Bass

The last time a saw such software for sale it was beyond my means. The few fre-shareware thingd I've seen assume a standard rectangular room.

The cheapest "instrumentation" availacle is Radio Shacks analog SPL meter coupled with a test disk. Not super precise but it identifies the grosser anomolies.

I've found the trouble with corner placement to be that it reinforces the level so much that slight changes to the sub's level control result in big changes in volume making it hard to adjust well.

There is a placement that I've heard recomended but has never been feasible for me - place it right next to your listening postion. The direct, unreflected energy will dominate so you can pretty much ignore the room effects. It may sound terrible for anyone else in the room but you, of course.
 
I have heard that you should place the sub at your listening position and then walk around and listen. The place where it sounds loudest is where you finally should have the sub.
While doing so very probably You`ll end up with 2 places where the sub is loudest:

1.)In the center of the room where the second lowest room modes corresponding the 3 widest room dimensions make a big bump. Obviously not only from the visual view this is not a comfortable position though the lowest room modes could be avoided to a big extend.
2.) In the corners of the room as all kind of room modes have their max. pressure level there. This place too should be avoided by all means. Otherwise the sub will best stimulate all these room modes to maximum and will cause bad ringing on them.

I don`t think this is a suitable method to figure out the best position for a sub but consider this rather a method which positions to avoid.

Though a couple of simulation software exist for this purpose, I doubt there are affordable ones which unless simple room dimensions are able to take in account properly all the other specific room properties as stiffness of walls, ceiling, floor, windows, doors etc. and their individual damping properties.

Therefore I guess still the best (and worth the money though not the cheapest as simple trial and error) method would be playing pink noise through the speakers and to use a narrow band (at least 1/3 octave) Real Time Analyzer (RTA) to find out the most even frequency response for different sub/listener positions. As due to lack of room space and other restrictions (for example as mentioned already visual acceptability) the positions mostly are predetermined to some extend this should not take too much time also.

I t is not very likely that there is a position which is optimal in every respect (as always, there is no free launch). Eventually remaining peaks can only be flattenend either acoustically (acoustic traps, big and expensive) or electronically with special designed equalizer circuits (parametric equalizers, small and cheap if DIY and flexible). For those having some reservations about additonal electronic circuity in the signal path, the electronic solution is particular useful with active fired subs where it has less to none bad influence on the upper frequency range.


to core:
I know all this does not bring You any further with YOUR sub-location problem (though might be useful information for others ).
I took a look at Your photos and so far I can judge this at all, I fear that it does not make make much difference where You locate the sub inbetween the possibilties that are left (which does not mean that the result have to be bad).
By all means You should take care about what said planet 10 about rainbow and the CRT-screen.
But as You plan to make the sub with its own amp., maybe what I said about electronic equalization maybe become useful at some time when You intend to tweak Your system.

P.S: I know from own experience that it is very troublesome to impossible to find the optimal place or setup via hearing music only. It is simply not possible to judge all the variations by ears only correctly. Besides this one always tend to trade one disadvantage against another without ever encountering what would be possible actually with some help of test equipment.
 
Bass optimization still in process

I had the good fortune to grab a pro level spectrum anayzer off e-bay about a year ago for a very reasonable price. It was one of the best buys I've made. It did two things - it made the locating and setting up my sub much easier and with better results and it let me evaluate and decide on accoustic treatment for my room.

I still have some additions to make as my budget permits. I need to add at least one more quarter round bass trap and absorption at a couple of other spots. Following that, I be looking at Behringer DSP8024. One realization I've come two is that EQ and acoustic treatment are not alternative approaches but complementary ones that -- each adds to trhe effectiveness of the other. EQ can only affect what comes out of the speakers while acoustic treatment affect what happens after that. My personal theory is the goal of accoustic treatment with regard to bass response is to reduce the spatial variations in the room, so that the bass comes closer to sounding the same everwhere, while EQ can then smooth out the response curve not just at my personal listen position by for a much larger area of the room.