Control Room Treatment

adam79

New member
I plan on buying a pair of JBL LSR305's. I've been debating between them, Yamaha HS5's and KRK Rokit 5 G3's for a while now. I still need to make my way over to the local music store and hear them first hand.

I know that the room acoustics are just as important as the equipment being played in it. The one thing I don't dig about the JBL's is their rear port. Is it true that they work best when place atleast 4' away from the wall (to minimize reflections)?

I'm not going to have much cash left over after this purchase so I'm looking for some suggestions on budget acoustic brands. I don't want to buy an inferior product just cuz it's cheap, but usually there's a company out there that competes with the big boys at a drastically lower price. I'm also considering building my own traps, etc. I'm definitely not opposed to using alternative materials with similar characteristics to the standard/more expensive stuff.

Thanks,
-Adam
 
So...are you asking what treatment to use in your control room...or are you asking if you should go for different monitors without the rear port...???
 
So...are you asking what treatment to use in your control room...or are you asking if you should go for different monitors without the rear port...???

I'm asking a few different questions:

-If there's a brand that offers budget acoustical material that sounds better than it's price would indicate
-If there are materials that aren't necessarily advertised as acoustic treatment, but had similar properties (and most likely a cheaper price)
-What a good instructional site is to build DIY traps and other acoustic stuff
-and finally if it's true that rear ported monitors should be placed atleast 4' from the wall to avoid reflections
 
GIK Acoustics

Not really

DIY Bass Traps

4' is better than 1'...but it's really about your room and what you can and can't do. Keep in mind that low frequency sound waves are much longer than 4'.
 
Thte JBLs either need to be placed away from the front wall, or have 4" thick rockwool traps behind them (that's what I have).
 
I'd go with *and* have rockwool traps. Every room needs it.

On substitutes -- packages of batts will work. Roxul Safe and Sound is a favorite. But heavy fiberglass does the job also. Keep in in the bags, stack 'em in the corners. It won't be pretty, but it's reasonably effective (although only a starting point / "base coat" of treatment) and about as cheap as you can get.
 
I'd go with *and* have rockwool traps. Every room needs it.

On substitutes -- packages of batts will work. Roxul Safe and Sound is a favorite. But heavy fiberglass does the job also. Keep in in the bags, stack 'em in the corners. It won't be pretty, but it's reasonably effective (although only a starting point / "base coat" of treatment) and about as cheap as you can get.

I've heard Roxul mentioned before as a DIY building material. It's recommended to have bass traps in all four corners of the room, right? Do you just need one per corner, placed on the floor? Or does it need to cover the entire corner, top to bottom?
What kind of savings will I be looking at if I choose to build them myself vs buying them professionally built? It sounds like there isn't much building involved if they just need to be stacked up and not even removed from the packaging!
I assume that I'll also need some kind of absorption material for the walls, especially the wall behind the monitors.

I definitely don't have the cash for all the materials necessary for ideal acoustics; I probably can only afford a couple items. Which ones would be the most helpful?

Thanks.
 
Yeah, all the stuff MM mentioned is usable...even though it's not advertised at Home Depot as "acoustic treatment.
I thought you meant stuff no one has previously used as acoustic treatment... most audio boards talk about the same tings MM mentioned.
 
Bass traps need to be floor to ceiling, if possible. Don't forget ceiling 'cloud' and 'point of first reflection' trapping, too.
 
For room treatment I would recommend Tontine Acoustisorb 3. It is easy to work with and non-allergenic, unlike glass or mineral wool which can be quite nasty. Build your own panels. It is quick and very inexpensive. Depending on your room size, try to,use 100mm panel thickness, although in certain areas you can get away with 50mm.

importantly though, measure your room response and check the effect each panel has, otherwise you could be wasting your time. Get a free package like Room EQ Wizard and perform a sweep response measurement to identify the frequencies of concern. For a small room this will probably be around The 90-120Hz range first, but there will be lots of others. Then prop a couple of panels up and redo the measurement, checking the effect the panel has on the response. this will give you the most effective outcome. It will also let you know what kind of response your room has after the treatment. Don't expect miracles, there will likely still be ugly nodes unless the room itself was purpose built with non-parallel walls.
 
For room treatment I would recommend Tontine Acoustisorb 3. It is easy to work with and non-allergenic, unlike glass or mineral wool which can be quite nasty. Build your own panels. It is quick and very inexpensive. Depending on your room size, try to,use 100mm panel thickness, although in certain areas you can get away with 50mm.

importantly though, measure your room response and check the effect each panel has, otherwise you could be wasting your time. Get a free package like Room EQ Wizard and perform a sweep response measurement to identify the frequencies of concern. For a small room this will probably be around The 90-120Hz range first, but there will be lots of others. Then prop a couple of panels up and redo the measurement, checking the effect the panel has on the response. this will give you the most effective outcome. It will also let you know what kind of response your room has after the treatment. Don't expect miracles, there will likely still be ugly nodes unless the room itself was purpose built with non-parallel walls.

All this information is awesome, but the one major problem is that the room I'll initially be using is only temporary. I'm going to have to buy all this treatment in stages; I can't afford everything in one sweep. Are any of the pieces I need interchangeable, i.e. one size will work no matter the room dimensions? Like for example a bass trap, or the absorption material for the wall behind the speakers? Also, isn't there some kind of material needed at the base of the speakers? Thanks.
 
All this information is awesome, but the one major problem is that the room I'll initially be using is only temporary. I'm going to have to buy all this treatment in stages; I can't afford everything in one sweep. Are any of the pieces I need interchangeable, i.e. one size will work no matter the room dimensions? Like for example a bass trap, or the absorption material for the wall behind the speakers? Also, isn't there some kind of material needed at the base of the speakers? Thanks.

Yes, you can deploy temporary treatment systems.
Plan on building some panels, around 1200x600 is a good size. Use 100mm thick material if the room allows it, and your budget can cover it. Otherwise start with 50mm high-density (Acoustisorb 3) panels.

I use a simple mounting mechanism where the panels are hung from the walls, allowing them to be moved if desired. The panels themselves are very light if you use something like radiata pine for the frames. I've built many of them over the years for different rooms. First build the frame out of timber, then stretch appropriate fabric over it and staple at the back. Then insert your block of insulation material and add the hanging braces across the back. You can also add LED strips if you are using them for lighting as well, that seems quite popular now.

The key is to make measurements and check the effectiveness of the panel and position at the frequencies of interest. Don't try 'using your ears', they will deceive you with all the comb filtering going on, which is very position dependent.

Once you have treated as far as your budget and patience allows, make sure you listen to all your favourite music through the monitoring system in the room. Spend a few weeks listening solidly to understand how it sounds. Now you can 'use your ears' as they are tuned to the monitoring system.
 
Also, isn't there some kind of material needed at the base of the speakers?
It depends on the speakers. If they are boxes then I usually sit them on some leftover acoustic isolation material (I use Quietwave membrane in the walls).
It makes little difference, as other room effects will swamp it. You can check this when performing measurements. Try with and without isolation (eg use 4 glass marbles to lift the cabinet off the surface). There will be no noticeable effect. Other room acoustic anomalies will have a far greater bearing on the sound.
 
As Miroslav points out, LF signals are MUCH longer than 4 feet (100Hz is 11' and I would expect a port to be tuned below that?) so why are REAR ports singled out for this restriction? (if indeed it is one) . If that JBL had a front port it would be less than a foot 'round the corner'. Bugger all compared to the anticipated radiation wavelengths.

Of course, if anyone has chapter and verse about 'Rear Port Obstruction' I would be pleased to read it? Meantime, I just don't get it.

Dave.
 
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