# Mac user needs help



## Coolhandjjl (Mar 22, 2010)

Hi- I'm trying to get a set up so my computer can be my spectrum analyzer with REW software. I have both a 1/3 octave equalizer, and full octave equalizers. Primary use is for home listening room, but future use would include a giging in a garage band set up with PA type speakers.

Is REW a freeware or do I have to buy a license? Looks like I need three things in addition to the software, a mic like the Behringer ECM8000, some sort of device to add phantom power to the mic, and an external USB sound card? Do I still need an SPL meter? 

It would be great if one of the Mac members could provide me with something like a shopping list of gear I need. I'm not a pro, so no need for high cost items.

Sorry to sound so helpless. This is all so new to me.


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## glaufman (Nov 25, 2007)

Hi there coolhand!
I'm not a MAC user, but some things to point out:
#1: If you have an internal soundcard, odds are you don't need an external.
#2: If you do go external, and you're on a MAC, don't get one that connects with Firewire. Go internal or USB.

Is that MAC an Intel or PowerPC?

REW is offered free. 

As for the SPL meter, it's recommended, as there is no other way to calibrate REW to display the absolute correct dbSPL numbers, BUT, strictly speaking, it's not "necessary." The exact SPL isn't so much important as how that SPL changes with frequency.

As a side note, if you were only using REW for frequencies less than 3kHz, you could use the RS SPL and not bother with the ECM8000 or the associated phantom/preamp.


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## Coolhandjjl (Mar 22, 2010)

Greg, thanks. 

My laptop is G4 PowerPC runing OSX 10.4.11 (Tiger), my big desktop is Intel OSX 10.6.xx (Snow Leopard), so in a perfect world, I'd like my old G4 laptop to be able to handle the task.

All I want to do is some RTA, so I can hit my EQ sliders where they need to go to get somewhat flat response. I'll need approx. 20~20K, I only mentioned the Behringer because the guys on the Bill Fitzmaurice speaker building forum mention it a lot, but they are mostly on PC and are using a PC only freeware.

So how do I go about finding a reasonably priced compatible mic and a pre-amp? Is that what the phantom power thing is, a pre-amp?


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## glaufman (Nov 25, 2007)

Well, I think people have more success with the Intel processors, but I think people have gotten results from the PowerPCs as well...
The Behringer is a fine mic, and is widely used for REW, so no issue there.
The phantom power is really to power the circuits in the mic, but many phantom power units also have the required preamps. In fact, a few external soundcards have phantom power and preamps built in that are usable.

So...

Let's start with the soundcard. What if anything do you already have in the laptop/desktop?
Also, consider buying the ECM8000 from Cross Spectrum which will provide a set of custom calibration files with it.


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## Coolhandjjl (Mar 22, 2010)

Here's what's in each machine:

PowerPC: Texas Instruments TAS3004 card
Intel: Intel High Definition Audio card

Attached photo shows screen shots of each system profiler with the audio hardware selected.


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## glaufman (Nov 25, 2007)

Well, the Intel specifically says line in and line out, whereas the PowerPC says line in (a good sign) but no line out.

My suggestion is to spend just a little money on the cable/adapter(s) to create a loopback connection (line out to line in) and see if REW will calibrate the soundcard properly. You can post a screenshot of the cal so we can confirm. If that works, chances are the rest will work and then you'll know it's ok to invest a little more money in the other equipment.


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## Coolhandjjl (Mar 22, 2010)

So I connect a mini phone jack from my headphone out to the mic in on my computer, run the REW sound card cal function?


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## Coolhandjjl (Mar 22, 2010)

sound card check box is greyed out. Ran a permission repair after I first initialized REW just to make sure. No change. 2 pics attached. First pic is what happens right upon launching, second pic is after REW initializes and the REW window opens up. The REW sound card panel makes another warning box come up, that is pic 3.

I'll try my Intel box next.


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## Coolhandjjl (Mar 22, 2010)

Intel Mac, much better. Seems to do what it is supposed to without any red warning boxes. Attached are two screen shots showing the loop back sound card cal.


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## glaufman (Nov 25, 2007)

Coolhandjjl said:


> So I connect a mini phone jack from my headphone out to the mic in on my computer, run the REW sound card cal function?


Probably not. Chances are the mic in is not high enough quality for this. do you have a "line in" connection?

Chances are the only way the mic in would work is if there was a setting in the soundcard drivers to switch it to a line in connection.


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## glaufman (Nov 25, 2007)

Coolhandjjl said:


> Intel Mac, much better. Seems to do what it is supposed to without any red warning boxes. Attached are two screen shots showing the loop back sound card cal.


The pix don't show the actual soundcard sweep....butl, if you think it's done right, we'll run one final check: leave the loopback connected and run a regular measurement sweep. It should come back flat.


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## Coolhandjjl (Mar 22, 2010)

Greg-

I'll look at that tomorrow. I just did the cal and raised ther volume until the bars hit the suggested 6~12 numbers, and tried quickly to get my screen shot before it dropped down. 

Regarding input and output, here is the rear of my Intel Mac. I used the analog in/out for the loop bak check. It is a miniature phone jack, I had a male to male cord laying around. There are also what they refer to as optical/digital in/out, the connectors look unfamiliar to me.


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## glaufman (Nov 25, 2007)

Yes, those "optical/digital" are what we refer to as TOSLINK, a version of SPDIF, and is for a fiberoptic cable. It was state of the art some time ago (the last time I bought any real equipment... but I digress...)

The way they labelled the input connection (as a mic input) worries me about the calibration. So post that sweep when you get a chance. Also look in your soundcard settings to see if you can switch that input from a mic to a line in or something like that.


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## Coolhandjjl (Mar 22, 2010)

Here's the sweep:


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## glaufman (Nov 25, 2007)

That's the soundcard calibration trace. In the best case, that will give you almost no useful info under 30Hz, and in the worst case it could be corrupted by either internal feedback or a samlpling rate mismatch. Let's do this next:

Make sure that cal file is loaded. 
Connect the loopback cable.
Run a measurement sweep as if you were measuring the room response.
Make sure the radio button "soundcard cal" is checked, and post a screenshot of what you get.
The response should be a flat line, otherwise we have more troubleshooting to do.


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## Coolhandjjl (Mar 22, 2010)

glaufman said:


> Make sure that cal file is loaded.


Where is that? Is it a separate download?





glaufman said:


> Make sure the radio button "soundcard cal" is checked,


What panel is that located?


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## glaufman (Nov 25, 2007)

Coolhandjjl said:


> Where is that? Is it a separate download?


No. That's what you're doing when you calibrate the soundcard. You're creating a file that contains data representing the soundcard's response. Once it's properly created and saved, REW will load it automatically every time it starts, and will use it to adjust the measurements you take to eliminate the soundcard's deficiencies from the measurements REW shows you.

Click Settings, go to the soundcard tab, and halfway down on the left side there's a box for a filename. If it's empty, it's not loaded.



> What panel is that located?


On the Filter Adjust tab, at the bottom, about halfway across the plot.


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## Coolhandjjl (Mar 22, 2010)

Sound Card Cal box is greyed out.
Cal file is empty.


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## glaufman (Nov 25, 2007)

It's possible you'll be able to find the cal file if you click "browse."
It's also possible you accidentally didn't have REW save the cal file.


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## Coolhandjjl (Mar 22, 2010)

Okay. I did it again, saved it. Screen shot attached. What's next?


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## Coolhandjjl (Mar 22, 2010)

Another creen shot. Set it to 20-20000hz


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## glaufman (Nov 25, 2007)

Well, I don't like that. Here's what I see (you can reset the vertical axis to 45-105dB for a look that will be more directly comparable to other posts here, but...)
The measured trace, assuming you've connected cable from out to in, should be a flat line. Below 100Hz, yours isn't. This will be an issue. The possible reasons for this are varied, so we'll need to do a little more work if we're going to get it right, but I'm starting to believe that input just isn't good enough and you'll need a different soundcard.


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## glaufman (Nov 25, 2007)

If you want to keep plugging along, the original cal almost looks like a sampling rate incompatibility, so the next step IMO would be to go to the settings window, in the top left you can change from 48kHz to 44.1kHz. Do this and re-run the soundcard calibration from that same window, save the new file, run a new measurement sweep, and let's see the results.


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## glaufman (Nov 25, 2007)

The other thing is, what options do you have for your "input device" on the top right of the same window?


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## Coolhandjjl (Mar 22, 2010)

44.1


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## glaufman (Nov 25, 2007)

Wow! Much Better! Take a measurement of the loopback to make sure, and change the vertical axis so it's +45dB to +105dB to show me the right amount of detail, but I actually think you're good to go!


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## Coolhandjjl (Mar 22, 2010)

Input settings


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## glaufman (Nov 25, 2007)

OK. Leave those input settings alone. Run the scan and post it with the 45-105dB scale.


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## Coolhandjjl (Mar 22, 2010)

glaufman said:


> OK. Leave those input settings alone. Run the scan and post it with the 45-105dB scale.



What is the 45-105 db scale?


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## glaufman (Nov 25, 2007)

Sorry. Click on "graph limits" on the top right, change the top and bottom settings to 105 and 45 respectively, click "apply settings".
This will change the vertical axis of the plot.


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## Coolhandjjl (Mar 22, 2010)

Disregard see next post


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## Coolhandjjl (Mar 22, 2010)

Corrected 45-105 attached. Last one had subwoofer instead of full range graph


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## glaufman (Nov 25, 2007)

Looks pretty good. There's a little glitch at 9kHz and another higher up, but that might not be anything to worry about. So... the choice is yours:
We could worry about that glitch, or
We could go ahead and figure out what equipment you want to get to run your actual scans with. If I had to guess, I'd guess this soundcard is going to work for you.


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## glaufman (Nov 25, 2007)

BTW, just to make sure, run one more measurement sweep, but instead of 20Hz-20kHz, run it from as low to as high as REW will let you (I think this is 0 Hz to 22.5kHz).


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## Coolhandjjl (Mar 22, 2010)

0-20,000. 22.5 reverted back to 20000


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## glaufman (Nov 25, 2007)

No matter, I'm satisfied. It looks like you clicked the 'freq axis" button... that switched the freq axis to LIN mode. Click it again to switch back to LOG mode. Always post in LOG mode. :T

I see one of the 2 glitches is there, but it looks like it's in a slightly different place... might just be a dirty connection, or might be some subroutine interrupting something. At those frequencies, if it was me, I wouldn't worry about it unless it gets worse.


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## Coolhandjjl (Mar 22, 2010)

Switched graph. I zoomed in tight, line is very smooth.


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## glaufman (Nov 25, 2007)

You're cleared for takeoff. :T


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## Coolhandjjl (Mar 22, 2010)

Okay now, so no additional sound card needed. Good. But I need a mic, and some sort of pre-amp/phantom power device?


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## glaufman (Nov 25, 2007)

Yes, but there are a few ways to skin this cat. One option is to get an RS SPL meter, that will be good up to 3kHz, and won't require phantom/preamp. Another is to get a Galaxy 140 SPL meter, which can be used for full range and doesn't require phantom/preamp. 
The top end of it all would be to get an ECM8000 or EMM6 (Dayton) mic. The Dayton I believe comes with fairly good calibration files. The ECM you would buy frmo a place like Cross Spectrum that'll provide more detailed calibration files (I believe CS also sells the Dayton with expanded cals). Either one of these will require phantom/preamp. There's a Xenyx 502 mixing board that is not expensive that will provide the required phantom/preamp.

EDIT: Almost forgot, if you get the ECM or EMM, you'll probably want an SPL anyway, to calibrate REW's SPL levels.


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## Coolhandjjl (Mar 22, 2010)

The Galaxy is $129.

But the ECM is about $50, and the Xenyx another $50? Radio Sahack SPL meter, what model, probably $50?


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## glaufman (Nov 25, 2007)

Right. And the ECM has the capability of the custom cal file, which can be done later even if you don't do it now (of course it's cheaper to get it done before ordering, Cross Spectrum's website advertises the ECM with a basic cal file for $80). (The Galaxy may have that capability as well, but I'm not sure).

For accuracy, people prefer the RS+ECM route over the Galaxy.


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## Coolhandjjl (Mar 22, 2010)

So if I order the ECM with the custom cal file, I navigate to that purchased file when running REW? What RS SPL meter is used, or do they only make one?


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## glaufman (Nov 25, 2007)

Yes. Before you order one, you'll want to consider which calibration package to go with, based on your use of the mic, but the mic will come with files. In REW you go to Setting->Mic/Meter and in there you can choose whichever cal file is appropriate.

There are 3 SPL meters from RS that have been used to the best of my knowledge, some may not be made any more. You can find specific info on them on our downloads page where you downloaded REW.


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## Coolhandjjl (Mar 22, 2010)

If I want to use my laptop, it appears that I will need to buy an external sound card. Any suggestions for that?

Thanks again!


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## Coolhandjjl (Mar 22, 2010)

Saw this one in the "SPL Meters-Mic's-Calibration-Sound Cards" Forum

Behringer U Control UCA202 USB Audio Interface

Hopefully it will work with my PowerPC laptop!


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## glaufman (Nov 25, 2007)

Coolhandjjl said:


> If I want to use my laptop, it appears that I will need to buy an external sound card. Any suggestions for that?


If you want, we can try and troubleshoot that laptop, but since I'm not a MAC guy, I'm not sure how far I could get...


Coolhandjjl said:


> Saw this one in the "SPL Meters-Mic's-Calibration-Sound Cards" Forum
> 
> Behringer U Control UCA202 USB Audio Interface
> 
> Hopefully it will work with my PowerPC laptop!


Do a search on Google to see if anyone's had problems/success/complaints between that SC and your OS. Many people use it successfully on PCs... but...

If you're going to get an external soundcard anyway, you could get one like the Tascams that have phantom power and mic preamp built in, might be more cost effective, not sure, and not sure how they work with MACs, so as always, search for problems/successes...


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