First Measurement. Ideas?

**Ross Winn** · **08-26-06, 06:35 PM**

First try of studio monitor in my small room. 11x17. Event ASP6. Any thoughts on tuning my measureing is appreciated.

**brucek** · **08-26-06, 07:38 PM**

Well, this is an full range active studio monitor that claims +/- 3db 40hz-20KHz and it looks like it's doing the job.

The only effect you can have with these is to provide some room treatment if you're not pleased with the lower end response.

Certainly you would not introduce any equalization with an active main.

What sort of ideas are you looking for?

brucek

**Ross Winn** · **08-26-06, 10:59 PM**

Bruce,
Thanks for the quick reply! This is a new graph with the studio door closed! The range has been expanded to 500hz. The monitors have been moved forward a bit and closer in. The mixes do not translate when moved outside of the studio. The bass is incorrectly heard in the mix leading to loss of bass when played away from the monitors.

**brucek** · **08-27-06, 06:28 AM**

I'm afraid I know very little about recording studios.

The response of your monitors looks not bad, although the room is causing a fair dip in the 70Hz-100Hz range. That's an area where a lot of bass energy is. In a studio you're listening near-field usually. A change in the overall sound is expected when listening outside the studio for that reason (I would assume).

You can turn on the trace-smoothing of REW to smooth the sharp jumps in the graph. These sharp spikes are usually inaudible.

brucek

**Ross Winn** · **08-27-06, 09:35 AM**

The room treatment is about as far as I'm going to go with it. The problem is the size of the room, which I can' t change. I get the idea the BFD is used usually to decrease peaks and not increase dips. I'm looking to smooth response. Doug, the creator of EFT's view is that electronic equalization after attempting room treatment is OK when applied sparingly. I would agree with that. Bad monitors generally can't be made into good ones with EQ, but good ones may be helped to improve the overall listening experience of the room.

How is it you can see the room response along with the speaker? I understand it is in the graph, just don't understand the difference.

Will I be able to, in your opinion, use BFD to correct room problems?

Thanks

**Ross Winn** · **08-27-06, 09:37 AM**

Bruce,
Do you see any problems with my testing/graph making, that may increase my results?

**brucek** · **08-27-06, 10:09 AM**

Quote:

I get the idea the BFD is used usually to decrease peaks and not increase dips. I'm looking to smooth response.

Well, generally if you want to add gain with an equalizer you will be using up available headroom. A small amount of gain (<=5dB) is fine if it's effective. But that's the rub. There are some room effects that defy gain correction. You can throw all the voltage you want at your power amplifier and the effect is minimal in the room response at that frequency. Other dips respond quite nicely to gain. I have found that this is a simple trial and error to establish with REW.

But, and this is a big but, I would never use a BFD for full range duties. It will simply add too much noise. I have both personal and anecdotal evidence of this. It is not studio quality. Its use is restricted to subwoofer duties where the noise is inaudible.

I agree with Doug. Room treatment is your first avenue. I thought any EQ in a studio environment was considered bad form?

Quote:

How is it you can see the room response along with the speaker?

I am making an assumption that the response you show is not the anechoic response of that set of speakers. You have a wide dip centered at ~75Hz that is almost -20dB. There ain't a chance it's the speakers fault. It's the room.

Usually anechoic speaker response is published - that should give you a better idea of what your speakers are capable of without room influence. There is a way of checking your speakers reflection free response with REW, but it severely limits the low frequencies in the response result - so that's not an option, but some people do a near-field response of their speaker outside to get a quasi-anechoic response.

Quote:

Do you see any problems with my testing/graph making, that may increase my results?

No, it wouldn't hurt to read this part of this sticky with respect to pre-impulse response window settings.

I think you're being kind to yourself using the vertical scale from 30Hz-105Hz. You might expand that to 45Hz-105Hz. The graph of course will look worse. You might modify your horizontal scale to start at ~30Hz. You aren't measuring a subwoofer, so the 15Hz you're using is too low.

I trust you're using the correct microphone calibration file and you've calibrated your soundcard...

brucek

**Ross Winn** · **08-27-06, 11:05 AM**

Speaker correction vs room correction is a sticky subject. When faced with a situation such as mine, small amounts of speaker correction is OK. It's about the ability to take great sounding mixes from the studio environment and have great sounding mixes in your car, home, computer, iPod.etc. I know the quality of these speakers is high, and yes, the curves in a chamber are very flat. So now I understand room curve vs the speaker curve!

I am mainly interested in the low end response, so BFD will be useful. Doug(EFT) reccomends it's use also. I'm going to try different speaker locations and listening positions to check for the effects of room modes on the REW graphs. It didn't appear that moving the mic faced towards the speaker or towards the ceiling made any huge change in frequency response. I would think moving forward and back in this small room could change freq. readings.

I do indeed have the calibration files for my mic loaded and have calibrated my sound card. I'll read the sticky as suggested and change my scaling. Thanks

**Ross Winn** · **08-27-06, 04:08 PM**

Here are some pre and post eq's to 500hz

**brucek** · **08-27-06, 05:08 PM**

The after looks quite good.

How are you integrating the BFD (if that's what you used) into the system? Is the entire full range signal passing through it or have you broken-out the woofer signal before the speakers amp somehow.

Either way, how does it sound? Is there any additional noise associated with the after EQ result?

You're down about 10dB at 40Hz, so not too bad. Does the bass sound OK?

brucek

**Wayne A. Pflughaupt** · **08-27-06, 07:43 PM**

Ross,

Welcome to the Forum!

Quote:

The monitors have been moved forward a bit and closer in. The mixes do not translate when moved outside of the studio. The bass is incorrectly heard in the mix leading to loss of bass when played away from the monitors.

That’s a familiar situation, I’m afraid. There are a couple of problems that relate to this.

I assume you’re in smallish room? The problem is that most rooms, especially symmetrical rooms (i.e., square or shoebox dimensions) have a null area or “bass hole” in the dead center. From there, the closer you move to any boundary, the more perceived bass intensity increases.

With a small room, you probably have your desk against a wall, or close to it. By the time you add the width of the desk and another few feet to where you’re head is, you’re pretty close to the center of the room – right smack in the middle of that “bass hole.”

To confirm this, do this simple test: Play some music and leave your chair and move towards a wall or a corner. I’ll bet you’ll find the bass level increasing the closer you get to a boundary.

The other problem is that small studio monitors deliver small bass. It’s extremely difficult to take a mix from them to a home system with even a modest subwoofer. Same with a decent car audio system. Your EQ’d response is nice and flat now, and I’ll bet it sounds really thin, if not shrill. I mean, you’ve got something like a 30-dB drop between 70 and 30 Hz! You probably need at least an 8 dB or more rise in response across that range – i.e., a house curve. You might want to check the house curve sticky thread on this forum’s index page.

Bottom line, add a subwoofer and you have a much better chance of getting a mix that will play well outside the studio. That won’t fix the “bass hole” problem – you’ll just have to optimize response for the listening position.

And, I echo brucek’s recommendation not to use the BFD for the mains. Sticking a $100 equalizer on a $1000 set of speakers is just wrong, especially if the problem you’re having is all in the bass region. Get a sub and you can equalize it with the BFD, and keep your mains free of extraneous processing.

Regards,
Wayne

**Ross Winn** · **08-27-06, 09:45 PM**

Bruce, the sound is not effected to great extent. A bit smoother I would guess. I'll have to see in a few days. 5 hours today was about as much as I could take. The speaker is not broken into separate components, so all frequencies pass through. The filter around 480 is pushed up to high and I think is causing distortion. I may reduce or eliminate this filter. I have to confess that I realized when looking at the back of one of the monitors that I had in the past jacked up the low end compensation 3db in an attempt to get better bass response!! This would lead me to mixes that would actually not have enough bass!! I'm going to try a short mix with the new EQ and see how it sounds in the outside world.

**Ross Winn** · **08-27-06, 10:37 PM**

Wayne, thanks for the insight and concern! My mix postion is about 6.5 ft off the front wall and the monitors are about 2.5 feet off the front wall. I moved them about using REW till I acheived the best-smoothest bass response. Then I filtered. I have many bass traps suspended which has helped tremendously to balance bass response thoughout the room, so as not to have much bass buildup.

I am concerned about the rolloff from 55hz down. I'm sure the Events do not drop off at this rate. Could this be a function of the room?

Bottom line, add a subwoofer and you have a much better chance of getting a mix that will play well outside the studio. That won’t fix the “bass hole” problem – you’ll just have to optimize response for the listening position.

I'd also like to say that I have less concern about the use of subs in the general public and feel they are not as common as 2.0 stereo, so I'm less inclined to add a sub to my system. Music is being mixed with lower freqs because the ability to reproduce them is easier for the general listener's stereo.

Are you saying that a sub will fill this space and when REW/BFD'd will better serve the overall sound? If so, I might try one. Any you'd recommend?

I'm attaching the Events freq response chart to take a look at.

**Wayne A. Pflughaupt** · **08-28-06, 10:21 PM**

Quote:

Then I filtered. I have many bass traps suspended which has helped tremendously to balance bass response thoughout the room, so as not to have much bass buildup.

Okay – The traps should help the “bass hole” situation, as I understand.

Quote:

I'd also like to say that I have less concern about the use of subs in the general public and feel they are not as common as 2.0 stereo, so I'm less inclined to add a sub to my system. Music is being mixed with lower freqs because the ability to reproduce them is easier for the general listener's stereo.

If you don’t have good full-range response, I don’t see how it can do anything but adversely affect your final mixes. For instance, judging from the chart in brucek’s post (#10) I’m going to hazard a guess that your mixes end up having overpowering bass when you take them to other systems. If that’s the case, it’s because your bass response is poor, so you’re naturally EQing to compensate. Again, you might want to take a look at Parts 2 and 3 of the house curve sticky thread.

Quote:

Are you saying that a sub will fill this space and when REW/BFD'd will better serve the overall sound?

Yes, that’s what I’m saying. Especially if I’m right about the way your mixes are sounding outside the studio. I’ve done a little mixing on studio monitors in a small room, and I had the same problem with the bass that you are. I think a sub really would have helped, because I was essentially “flying blind” as far mixing and EQing the bass was concerned. REW will tell you if the sub needs equalizing (as you know), and the BFD will take care if it, if needed.

Quote:

If so, I might try one. Any you'd recommend?

That’s a toughie, because I imagine you want one with balanced inputs. Probably any of those will be pricier than regular home theater or home stereo subs, although a good-quality 10" home sub is probably all you need (assuming your room is pretty small). SVS, a popular brand with the enthusiasts that frequent the home theater forums, is about to come out with a sealed 12” sub, the SB-12 – probably way more than you need, but it does have the balanced inputs. You can get good deals on them since they’re mail order only. You’ll probably get better detail for music reproduction with a sealed sub rather than ported (although that’s not always the case). Maybe your local pro audio dealer, or the pro section of a guitar shop, will have some studio-friendly subs.

Regards,
Wayne

**Ross Winn** · **08-28-06, 11:07 PM**

I sent an email to Bruce comcerning the fact that I'm using the oldest RS mic and the cal file I've used is for the one that came out after mine!! This is one reason the bass response has such a severe rolloff. I don't know if the correct file is available anywhere or if I'm going to have to buy another mic before proceding!! Your assumption about post mixs being overly bassy make sense when looking at the current graphs. Actually they tend to be light on the bass. I'll have to redue after fixing the mike problem. Any ideas on a reasonable mic or should I buy a RS again?

I would think the info concerning buying a sub still is valid and yes there are a couple pro audio units availble for not a lot of cash that will have the balanced input. They are also self powered, around $300.

**brucek** · **08-29-06, 07:06 AM**

I believe there were only three RS type meters ever made. The original (old) meter was around for a long time and then they updated it and also started selling a digital one.

The three calibration files are available here.

What cal file were you using?

brucek

EDIT post: OK, on further investigation after remembering that there was a meter #42-3019 that we didn't think was around any more, I found the supposed calibration file for it.
This calibration file, wasn't very resolute and had been kicking around the internet for many years. I can't vouch for its accuracy since we only used the three meters listed above for our tests. Sonnie used his professionally calibrated ECM8000 to establish the cal files for the three listed and never tested the 42-3019.

Here's the file for the #42-3019 that I had on file and also found on the internet. Just copy the contents to notepad and save as RS.cal

RS.cal

Code:

10.000  -20.000  0.000
12.500  -16.500  0.000
16.000  -11.500  0.000
20.000  -7.500  0.000
25.000  -5.000  0.000
31.500  -3.000  0.000
40.000  -2.500  0.000
50.000  -1.500  0.000
63.000  -1.500  0.000
80.000  -1.500  0.000
100.000  -2.000  0.000
125.000 -0.500  0.000
160.000  0.500  0.000
200.000  0.500  0.000
250.000  -0.500  0.000
315.000  0.500  0.000
400.000  0.000  0.000

Perhaps it would be wise to get a new RS meter since they're so cheap.

brucek

**Ross Winn** · **08-29-06, 10:13 AM**

Bruce,
Thankx for digging up this info!! I think I'm going to RS to check on a newer model and price anyway. I am wise and cheap and the meter I have is about 23yrs old!!!

Ross

**brucek** · **08-29-06, 10:16 AM**

Quote:

On the above referenced page I have the meter that is on the bottome that says there is not information available for!!

Yep, and the file coded above is the cal file to use with it.

Nice to get a new meter though....

brucek

**Chrisbee** · **08-29-06, 12:24 PM**

If nothing else having two SPL meters give one the option of eliminating the meter as the culprit when a problem like your rapid bass rolloff crops up under test.

I have hoped for the last 15 years that my SPL meter would turn out to be perfectly flat when tested against another. No other response ever made any sense when my sub shows a +30dB house curve to 15Hz at the listening position! I had exactly the same problem with my previous DIY bandpass boxes in an even larger listening space.

I'm tempted by one of the new soft-look analogue meters myself.

**Ross Winn** · **08-29-06, 08:34 PM**

Got the new meter, loaded the correct file and did some measurements. Then I worked the filters and this is what I got. Comments welcome of course.

**brucek** · **08-29-06, 10:00 PM**

Can you change the vertical scale to 45dB-105dB and repost...

**Ross Winn** · **09-01-06, 04:24 PM**

Hey!
This a new graph with the sub added as Wayne had suggested to even the bottom out and boy did it! It's a KRK 10s 10" w/ 200 watts. It has a variable LF cutoff from 50-130hz. There's also a nasty dip at about 75 hz that I'm BFDing out of there. Is this a crossover problem? Take a look.

**brucek** · **09-01-06, 04:57 PM**

Looks good, with much better low end extension. Most people prefer their sub a bit hotter than the mains though. If you turned the sub amplifier up a bit and then added a house curve by slowly cutting from about 40hz down to the crossover, you might like the sound even better.... You should read Waynes sticky on house curves.........

brucek

**Wayne A. Pflughaupt** · **09-01-06, 05:04 PM**

Big improvement! Bet is sounds better, too.

Quote:

There's also a nasty dip at about 75 hz that I'm BFDing out of there. Is this a crossover problem?

Since it wasn’t there before – yes, it’s probably a crossover problem. The BFD can usually fix those.

Regards,
Wayne

Advertisement