OK.. where to start ?

Hi all,

Right... I think I've got my SPL meter and PC set up correctly.. sound card is calibrated, levels set, REW SPL calibrated, perhaps I'm ready to take measurements ? I'm a little unsure where to go from here.

I don't have a sub (and I wasn't planning on buying one, due to the size of my room, and my situation with neighbours), just some new 3-way floor-standing mains. My old 2-way monitor speakers have been moved to the back of the room to act as surround speakers in preparation for eventual HT. I've recently also bought my centre channel speaker.

I don't have a surround receiver/processor yet, just working with my old hi-fi integrated amp at this point, concentrating on getting the room right for music at least. So my new centre speaker stays in it's box for a while.

I don't have a graphic equalizer, only the basic tone controls on my amp (NAD 3240PE). And I certainly don't have one of those BFD thingos.

What I DO have by the proverbial truckload is standing waves, and they're absolutely killing me !

I've had a look at a couple of different "room mode" calculators, and after entering in the dimensions of my lounge room (L15'6", W11'6", H8'1"), I find the results hard to decipher.

Should I be playing around with room mode calculators and posting results here ? Or taking measurements with REW... ? Are these tests supposed to be performed one speaker at a time, or both mains/all HT together ?

I've learned a of a lot over the past few days, and am feeling quite like a "saturated sponge".. In some respects I feel like I'm losing the plot... hehe... somewhere in there was a goal to find out what's wrong with my room, and figure a strategy on how to fix it with DIY bass traps, etc... all on a tight budget !

I'm at your mercy in my request for guidance !

[brucek]

I don't have a sub

I don't have a graphic equalizer

I don't have a surround receiver/processor

Well, most people use REW to check the response of their subwoofers and then enter the suggested filters into a BFD (parametric equalizer) to smooth out the response.

REW is also useful for taking a room response to facilitate the best spot to position subwoofers and speakers. It is also useful in checking the results of bass traps and treatments.

Note that all the response sweeps are usually taken at low frequencies where the room modes have the greatest effect. Also note that the Radio Shack SPL meter is only accurate at lower frequencies. Don't trust it above 5Khz.

For subwoofers we usually use vertical graph scales of 45dB to 105dB with 75dB REW targets and a horizontal scale of 15Hz to 200Hz.

You could start there and check the response of your mains to see how they behave in that area.....

brucek

Incidentally, please forgive me, I was posting on a different (non-specialised) forum before posting here, so I may assume that I have provided all the details about my situation that I should have, when I actually haven't. Please, ask is there's more info required and I'll happily provide it ASAP. And I really do appreciate all your help !

brucek wrote:

Well, most people use REW to check the response of their subwoofers and then enter the suggested filters into a BFD (parametric equalizer) to smooth out the response.

Guess that means I ain't "most people". REW was suggested to me from an audiophile on another forum - that's why I'm here.

REW is also useful for taking a room response to facilitate the best spot to position subwoofers and speakers. It is also useful in checking the results of bass traps and treatments.

That sounds more like what I'm doing. I'm hoping I can figure out where those bass traps (or other suggested treatments) will need to be placed, how many I need to build, and to what specifications.

You could start there and check the response of your mains to see how they behave in that area.....

OK... I don't know how to interpret the results AT ALL so I hope it's OK for me to post them here. Also, should I leave the program at it's default settings for the measurements.. are there no settings I should adjust ?

Also, should I draw up a diagram showing my room layout and post it ?

I'm not even sure I'm going about all this the right way in the first place. I thought it might be wise to get my room sorted first, and then start researching/buy a receiver... at least then if there's some type or specific feature that I need, I can target it, whereas if I buy it up front, I'll be stuck with the "wrong" purchase.

Another thing I'd also like to do, is to continue using my NAD 3240E integrated amp for music if possible. Or, failing that, use it in some way in my system once I've bought the receiver... as I simply don't want a good quality component sitting there doing nothing. I know nothing really about "pre-amps", so maybe there's a role it (or the receiver) can play there.

[brucek]

Also, should I leave the program at it's default settings for the measurements.. are there no settings I should adjust ?

The entire setup for REW is found in the REW HELP FILES.

brucek

[Sonnie]

OK... I don't know how to interpret the results AT ALL so I hope it's OK for me to post them here.

Yes... you can get lots of help by posting your response graphs... but be sure to read the sticky threads on posting graphs too... lots of reading to do...

Also, should I draw up a diagram showing my room layout and post it ?

That would probably be more useful for the guys in the acoustics forum. The BFD will help you in the extreme lowest parts of your response. For 80Hz on up, room acoustics are generally dealt with by using various acoustical treatments... and we got the guys to help you with that as well...

[Wayne A. Pflughaupt]

I'm hoping I can figure out where those bass traps (or other suggested treatments) will need to be placed, how many I need to build, and to what specifications.

I don’t think REW is going to help you with that. The bass traps experts that hang out at our Acoustics Forum can probably tell you what you need in the way of traps, and where to put them.

Regards,
Wayne

Wayne A. Pflughaupt wrote:

I don’t think REW is going to help you with that...

I hope that's not the case. I thought I needed the SPL meter to tell me where the problems lay, and then folks who are more experienced could tell me what I need to do from the results ? Otherwise, I've wasted over $AU50 on the meter and cabling/plugs, which could have been spent better elsewhere (I'm a pensioner... can't afford to waste money like that!)...

[brucek]

And I certainly don't have one of those BFD thingos

That's how we take care of the very low frequencies that traps and treatments can't.....

brucek

TassieDevil wrote:

I hope that's not the case. I thought I needed the SPL meter to tell me where the problems lay, and then folks who are more experienced could tell me what I need to do from the results ? Otherwise, I've wasted over $AU50 on the meter and cabling/plugs, which could have been spent better elsewhere (I'm a pensioner... can't afford to waste money like that!)...

Well if you hop over to the Acoustics section I think you'll find that in a room like yours (small-ish) the first thing to do is to put bass trapping in. The more the better. Hit all the corners with bass traps then hit the first reflection points. Then measure with SPL to see what's happening with the mids and highs.

Good luck
Michael

OK, I'll head over to the Acoustics section. Guess this is the wrong area for what I'm trying to do... apologies...