Speaker placement for bass response

CWK

I'm setting up my system in my unfinished basement, no interior walls, just framed up, carpet on the floors, exposed floor joists 10' up. followed the instructions by placing the listening chair at one point of the equilateral triangle (approx. 12' corner to corner) near the center of the room. bass seems very shallow. i stand closer to the speakers, nearly between the two mains, and bass, of course is clear, big and tight. stand far back from the speakers up against a true wall, approx. 16-20' back and bass is just as big but boomy. borrowed a 150w powered sub from the next door neighbor. didn't help. not one bit!

what determines how bass energy sets up in a given room? don't want to keep rearranging the stereo/furniture just to find the right bass setup. any direction?

framed up space is 14' x 22'. speakers (LSi15's) are on the 14' interior end (no walls.)

should i put the speakers up against the solid wall?

should i put the speakers on the 22' side and spread them out farther than 12'?

please send ideas.

pushing the system with 110wpc, yamaha receiver.

(if you're wondering why i'm not setting this in a proper room upstairs, it's because my wife says my stereo equipment doesn't "go with" her furniture or other decorations.)

steveinaz

Alot will depend on the speaker design; if they're rear ported, close placement to back walls can result in boomy bass. Distance from the rear wall is probably the biggest factor, closer to the back wall you go, ther more bass reinforcement you get.

I would not spread your speakers any further than 12', you may end up with a "hole" or loss of center imaging by doing so.

Experiment with off-set corner loading a bit. Experimentation is the only way you'll get the ultimate tuning of your bass frequencies.

reeltrouble1

The old trick is to hook up the sub and then put it in your primary listening position, then crawl around on the floor of the room until you find the spot where the bass sounds the best, this is the likely place to put your sub for your room.

RT1

billbillw

CWK,
I'm really starting to think that you just don't have enough power to drive those LSi15 in a big room like that. You can look all around here and everyone recommends a good high current amp to drive the LSi. Bass response is the first thing to suffer when power is lacking. You can move them all over your basement and you may find subtle improvement, but I don't think you will really get what you are looking for without additonal power.

unc2701

wait a sec- It's just framed, right? No drywall yet? Get some solid walls in before you make any judgements.

jmierzur

As with real estate, it is all a matter of location. Try experimenting with different placement options. This should get you started.

Link

CWK

Thanks for all of the thoughtful responses:

jmierzur - i got the link but all of those methods assume you've got walls, which i don't have. it's an unfinished basement and wasn't planning on finishing it when i bought the speakers.

unc2701 - are you telling me that you MUST have walls for the bass to set up properly? i guess it's possible but i don't buy it.

reeltrouble1 - good tip but i've already crawled around on the floor extensively. my 2.5 year old son thought it was funny to ride my back most of the time. bass is poor close to the floor. i got on a ladder (sans 2.5 year old.) bass is huge up there about 8' up. boomy though. not much help. the sub was a complete bust.

steveinaz - the lsi's have side firing woofers but down ported. what do you mean by off-set corner loading? remember i only have one solid wall to play with.

billbillw - i thought power was the problem too but now i don't. many areas of the room have big bass. it's boomy near the back solid wall and up on the ladder but there are other areas where the bass is big and crisp. it's just more hollow near the center of the room at sitting level. if i crank on the volume knob or equalize the low freq's up, i can get plenty of bass at the proper sitting position. but more power's not really the answer. i need to get the speaker placement right. i'm actually thinking of returning these lsi's.

couple of problems. finicky bass response is one thing. efficiency is another. these are 4 ohm speakers and the mid/high freq's are pretty quiet. they are rated at 88 db spl. that's not real efficient. and my receiver gets real hot even at moderate volumes. the htr-5790 is rated for 8, 6 and 4 ohm loads but i've read that the yami's don't like less than 8. my experience seems to confirm this.

will try moving the speakers up against the solid wall to see if that makes any difference. next move will be to try different speakers, maybe the rti 12's. after that, i may have to take unc2701's advice and go get some sheet rock.

billbillw

I don't think drywall will give you more bass, but it will clean up the bass and the sound overall. Drywall will absorb some of the soundwaves, whereas concrete will reflect most of the waves and create areas with converging waves that create muddy, boomy, increased, and or decreased bass depending on how far out of phase the waves are. Concrete will create nighmarish coloration in the mids and highs as well.

I still think that more power would be part of your solution, maybe not all of the solution, but you did mention that your mids and highs are laid back and your reciever is running very hot. In the end, if you don't want to invest in better power, these speakers may not be for you. You may be better off with something else. Where did you get the speakers? What is their return policy?

Edit: Ok, I read a little more on your placement and room design. I didn't notice that you said "framed area". I was thinking that the entire size of the basement was 22x14 and the walls were all concrete. If the space is larger than that, its no wonder you are not getting a lot of bass. You have to consider the actual volume of air that is being moved by these speakers. If these are placed in the middle of a large air volume, the bass will be minimal, but should be tight if supplied with adequate power. You should definetely have these placed within 2-3 feet of a solid wall to get the right bass response. Closing in the areas with drywall will decrease the volume of air that the speakers need to fill and should greatly increase the bass.

CWK

billbillw,

i got them from hifibuys (tweeter.) they have a good return policy. 30 days no questions asked (i've got about 2 weeks left.) 1 year full credit on upgrade.

when i bought the lsi's, i actually was going in to buy the rti 12's. the sales guy, correctly, showed me the next level up ($100 more). they sounded good in the showroom. he said he was driving them with a yami 110 wpc receiver with no sub. i believe him but there is a stark difference in the performance in the dedicated sound room and my basement.

the funny thing is, i've got an old set of rta11t's. hooked them up in the front last night and the bass response was deeper and sharper than the new lsi's. sounded pretty damn good actually. still a little hollow in the center of the room but not as much. those are 6 ohm / 89 db efficiency (i think.)

you know anything about the rti 12's? it's almost pointless to assume the demo results will be applicable to my basement.

billbillw

Yeah, those sound rooms are usually less than 200 sq ft, with low ceilings and acoustic treatments. The RTi12 will definetly have more punchy bass and would be better matched to your receiver.

unc2701

Ok, drywall vs concrete, no big deal, you can still get an idea of what it'll sound like no problem, however, if you've got a 22x50 ft basement and just framed off a 22x14 foot section of it, that REALLY matters- Basically you're having to fill the whole space and that'll seriously effect your sound. Those open joists above will also screw around with it too, but your biggest problem right now is that you're having to push them to fill your entire basement.

So get some walls up before you make your final decision.

billbillw

Originally posted by unc2701
So get some walls up before you make your final decision.

He might not have time to get a drywall job done before his 30-day window for return is up.

unc2701

good point. Got another room in the house that's about the same size?

CWK

i've got a room the same size upstairs. basement layout is a duplicate of the main floor. but first, i'm going to try moving the lsi's to the one solid wall tonight. if i notice some improvement, i may sheetrock the first 6-8' of the side walls to give a little extra enclosure. that won't take long + pretty cheap test. we'll see what happens.

jmierzur

CWK, your post contained:

- I'm setting up my system in my unfinished basement, no interior walls, just framed up, carpet on the floors, exposed floor joists 10' up.

- framed up space is 14' x 22'. speakers (LSi15's) are on the 14' interior end (no walls.)


As per your post, I guessed your entire area is 14’ x 22’ and the exterior walls were framed up as you stated you have no interior walls.

All rooms have walls. In essence, your acoustical environment is larger than 14’ x 22’ due to the incomplete ‘framed up’ ‘interior’ walls. The physical dimensions of this room may be 14’ x 22’ (unless you can walk between the studs).

I would be looking at setting up the system within the ACOUSTICAL environment. As per your last post, I agree, place the speakers along a solid wall as a starting position for speaker placement. The solid wall will give you some boundary gains you can work with as apposed to placing the speakers in the middle of the acoustic space.

If the positioning does not provide the results you are expecting, keep fine tuning the location. If your listening position encroaches on one of the ‘framed up’ walls, do not worry about it. The framed up wall does not delineate the acoustic environment.

Not sure if your test along the solid wall will be any indication of the performance of having the framed wall boarded for 6’ to 8’. I guess you can always try.

Better yet, complete the framed space you currently have; place temporary flooring etc. You can finish the basement at a latter date. Many would do just about anything to have a dedicated listening room. Not sure why you are resisting completing a dedicated listening room, but building one in our basement was one of the best projects I have completed.

CWK

jmierzur,

thanks for the post from the great white north (AB).

the entire basement is much bigger than the 14 x 22' framed up room my stereo is in. probably more like 60 x 40' total, pretty open, not too much stuff down there. the 14x22' room has the desk for the receiver / dvd player, the entertainment center for the 30" flat screen (not hi-def - i wish), 2 couches, upright piano and my leather listening chair. speakers currently in the corners of framed wall. will move to the solid wall tonight to test differences.

overall performance of the speakers is downright acceptable. it's just the hollow bass spot in the center of the room where the listening chair would need to be. i could sit in up closer to the speakers and catch all the bass i want. but i've got to find the sweet spot.

and no more cracks about me resisting finishing my own listening room. that is near the top of a bunch of projects that i've had to put off. the top project is two little twin girls, 12 weeks, and one highly active 2.5 year old son. i just tinker with this stereo thing in my "spare" time thinking that some day i may have a life again to pursue it further.

jmierzur

I can relate to your situation; finished our basement one week before our first child was born. :eek: Can't say I would have time for projects this size now. Three years later and two children, I still do not have "spare" time for the pleasures I once enjoyed.

You may be sitting in a null spot for some of the bass frequencies.

Try seperating the speakers about 80% of the listening distance. For example, the speakers will be 8' apart if your listening position is 10' from the speakers. This will give you a better defined center of the soundstage.

In addition, can you move the desk from the room to another location in the basement and place the reciever and player in or by the entertainment center, or between the speakers. Remove one of the couches??

Hope you find your ideal listening position. Let us know how the outcome of your experiments.

JM (from the Great Brown North)

PS. If you have some boxes, try stacking them along one of the framed walls.

CWK

JM,

good tip, moving the speakers in to 80%. will try this after moving the speakers against the solid wall.

and, yes, i can move the desk, couch, anything. but what is your point? you think the less stuff in the room is better?

jmierzur

Try 80% on the current location. Make note of the results, then move to another location, etc.

My point is to balance the room. Will it make a difference? Possibly.

Have fun.

CWK

has anyone ever tried the YPAO feature to let the receiver find the sweet spot? i tried this yesterday with mixed results. it didn't help the hollow bass zone in the center of the room. it did move the boomy bass spots around some. there was some improvement on the mid/high freq imaging though. nothing major.

but should i set the optimization program back to the default before speaker location experimenting? I would think so.

any experiences with the ypao. is this something i should be using at all?

unc2701

This is just me, but I hate it... it'll crank one speaker up to clipping if you're not careful. A radioshack SPL meter is the better way to go.

CWK

i moved the speakers up against the solid wall. that along with JM's 80% spacing idea improved the bass response significantly. i think i might be on my way to solving this problem.

the hollow bass zone in the center of the room is gone. or at least it's moved to the sides now. i plan to keep tinkering with the placement but am confident i'll be satisfied. thanks to all the helpful posts.

a very surprising side note - i hooked up my old speakers, polk rta11t, ca. 1988, exactly where the new lsi 15's were. well, the bass was perfect. there was no bass hollow spot in the center. they were out in the open just like the lsi's were. i've fallen back in love with those old 11's and starting to wonder about the new 15's. hmmm.

scottnbnj

Originally posted by CWK
the hollow bass zone in the center of the room is gone. or at least it's moved to the sides now. i plan to keep tinkering with the placement but am confident i'll be satisfied. thanks to all the helpful posts.

hollow bass near the center of a rectangular room is typical due to cancellation. the increased bass you heard near walls is to be expected also because the direct and reflected sound arrive at nearly the same time so they reinforce each other, instead of cancelling or smearing.

the room will behave and sound different with a ceiling, drywall, insulation and furnishings and you will probably start your work, nearly, from scratch after the room is done. while you get things put together you might start searching the net for articles about room acoustics, modes, treatments and bass cancellation if you want detailed explanations of why.

there are also many freeware room mode calculators on the net that will help you understand what's going on in a rectangular room and maybe even help you set it up and design it. here are 2:

http://www.realtraps.com/modecalc.htm

http://www.mcsquared.com/modecalc.htm

you can account for furniture by subtracting cubic footage of the furniture, though all of this will only give you a rough idea of what could happen without taking into account materials being used and many other variables. most folks don't bother with all of this and get great results with combinations of experimentation, doing what others have done, good guesses and/or luck.

to get a quick and dirty idea of why what has been said above is correct in regard to how your room will behave differently after it is finished you should plug your basement size into the calculator, then your proposed room.

the differences in materials, the studs lined up along the foudation walls and the first floor joist cavities will change the equation a bit, but should give you an idea of what you're up against trying to predict exactly where waves will cancel, their strength and many other details of what it will sound like before finishing.

)

p.s. for finding the sweetspot, a chair with wheels works.