Newbie: Mike versus SPL

**dvenardos** · **01-22-09, 02:24 PM**

I am getting the equipment to be able to use REW. I am in the process of acoustically treating my room and I want to be able to get before and after frequency response. In addition, I would like to be able to get the best position for my sub and calibrate my HT speaker levels. I have always done this by ear.
Can I do all this with either a mike or spl meter, or is one better than the other?

I am looking at getting the Behringer UCA202 usb interface and either the ECM8000 and mixer or Galaxy CM-140.

Thanks,
Don

**tonyvdb** · **01-22-09, 02:28 PM**

Hi Don, Welcome to the shack.

no matter what mic you get you will still require an SPL meter and the CM140 is regarded to be the best for the money.

**dvenardos** · **01-22-09, 02:33 PM**

Quote:

tonyvdb wrote:

Hi Don, Welcome to the shack.

no matter what mic you get you will still require an SPL meter and the CM140 is regarded to be the best for the money.

Thanks.
So, would I be okay with just the SPL meter or will I need a mic also, or does the mic just give you more accurate results?

**brucek** · **01-22-09, 02:38 PM**

Quote:

would I be okay with just the SPL meter

Yep, the CM-140 would be fine for all your work (along with our CM-140 calibration file)...

Read and become familiar with the REW HELP files and the REW Cabling and Connections Basics.

Also note the REW information Index and the Download Page.

brucek

**dvenardos** · **01-22-09, 02:41 PM**

**salvasol** · **01-22-09, 04:06 PM**

Quote:

dvenardos wrote:

I am getting the equipment to be able to use REW.

The Radio Shack SPL meter has a mic already, so you can use it for REW, the downside is that is good only up to 3KHz, so to calibrate a sub is good.

To get readings above 3KHz, is better to get the CM-140.

**dvenardos** · **01-23-09, 03:11 PM**

Just ordered the CM-140 and the UCA202 from American Musical Supply, great price.
Thanks for the help.

**rentangz** · **02-18-09, 04:25 AM**

You mean the RS SPL meter is good only up to 3khz?can we not use this to measure or calibrate the whole sound spectrum?

**brucek** · **02-18-09, 11:58 AM**

Quote:

You mean the RS SPL meter is good only up to 3khz?

Correct.

Quote:

can we not use this to measure or calibrate the whole sound spectrum?

No. A Galaxy CM-140 would be a better device to use.

brucek

**Torzel** · **02-19-09, 12:55 AM**

Hi Don;
Take a look at the following link. Ethan Winer tests 11 different mics and the radioshack SPL meter. He concludes that the Behringer is a great mic for the purpose.
www.realtraps.com/art_microphones
(I have fewer than 5 posts and the system does not allow me to post website links -- hence the cccc and the space)

**Torzel** · **02-19-09, 01:03 AM**

Here is the real link: www.realtraps.com/art_microphones.htm
(last post was my 5th)

**rentangz** · **02-19-09, 10:59 AM**

The CM140 specs states that the freq response is 31.5hz to 8khz only.How will this affect the measurements above 8khz up to 20khz?

**Torzel** · **02-19-09, 03:38 PM**

The CM100 is full range as seen by tests done be E Winer. I don't know about the CM140

**brucek** · **02-20-09, 12:24 PM**

Quote:

The CM140 specs states that the freq response is 31.5hz to 8khz only.How will this affect the measurements above 8khz up to 20khz?

The response is flat from 10Hz to 20000Hz when used with REW and our calibration file.

brucek

**nab9524** · **04-11-09, 02:23 PM**

So if the CM140 spl meter is flat from 10Hz to 20000Hz with a cal file what are the benefits of using the ECM8000 mic and mixer? The price difference between the two is small. Initially I will be using this to setup my sub, but I would also like to evaluate my other speakers in my room. I am using Audyssey in my prepro but unfortunately at this time I am not able to see the before and after affects. Which of the two options would best suit my needs?

thanks

**brucek** · **04-11-09, 03:21 PM**

Quote:

Which of the two options would best suit my needs?

With the ECM8000 and mixer option, you still require an inexpensive SPL meter, such as the Radio Shack models.

The ECM8000 allows you to run a long balanced cable from the mic to the mixer with a minimum of noise. The SPL meters unbalanced cable may offer a bit more noise if you use a long cable. This generally won't be an issue in a home where the cables are all fairly short.

The SPL meter has a range switch and so the signal must remain in that spread or clipping can occur. This can be a problem for RS meters if you have very large peaks in the sub signal, but the Galaxy has a fairly wide 50-100db position that shouldn't suffer from this problem.

The mixer offers a wide range of adjustablity to take care of the input needs of any soundcard. The SPL meter has a fixed line level output.

Generally, I think the Galaxy is the best option.

brucek

**nab9524** · **04-12-09, 07:20 PM**

Thanks for the info brucek.
So when using the mic the only need for an spl meter is to adjust output to ~75db, is that correct?
Does the mic have an optimal spl range to work within or any limitations I should know about?

**brucek** · **04-12-09, 07:40 PM**

Quote:

So when using the mic the only need for an spl meter is to adjust output to ~75db, is that correct?

Yes.

Quote:

Does the mic have an optimal spl range to work within or any limitations I should know about?

It would have to be the 50-100dB scale since you're measuring around a 75dB target.

brucek

**Sycraft** · **06-11-09, 07:53 AM**

I will add, having gotten a CM-140 this week and having played with a number of SPL meters in the past that it is a real nice one to use. I can't speak for its accuracy or anything, I'm sure there are plenty of posts here with lots more information on that then I'll ever gather, but it is in general a good SPL meter.

One thing I really like is that it seems to be quite responsive, without being twitchy. Way too many SPL meters are really twitchy, even in their "slow" weighting. It makes it real hard to get a feel for what level you are dealing with, especially when they are digital and there isn't a smooth gauge to follow.

The CM-140 I find nice and usable. Thus far I've used it to check some volume levels at work (like the noise in our server room) and played with it checking SPL vs my volume dial on my system. In all cases I've found it to be easy to get a reliable reading. Even in fast mode, it doesn't seem to jump around, unless of course there is a spike in sound.

Also, I think it's A weighting is pretty good in terms of the "feel" of room noise. What I mean is that in A mode, the value it gives seems to correspond pretty well to how loud the noise in a room sounds to me. Now that would be the idea of A weighting, of course, but I've found that doesn't always work. However on this meter, seems to be good.

So far, I'm real happy with mine. Even if it ends up being a total bust in terms of calibrating my speakers (which I doubt) it is a useful gadget for measuring noise levels.

Edit: Also, it has a mount on the bottom compatible with standard camera tripods.

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