# Preparing for first run through



## wgb113 (Jan 12, 2012)

I've downloaded the latest version of REW in hopes to 1) help find the optimal listening and speaker position, and 2) identify problems in my room/speaker interaction (full range) that can be treated with room treatments and 3) use judicious PEQ as icing on the cake to pull down any remaining peaks.

My equipment is as follows:

iMac running Lion
Behringer DEQ2496
Benchmark DAC1 USB
Dynaudio BM5A MkII
Behringer ECM8000
RadioShack analog SPL meter

The iMac is connected to the Behringer via optical. Audio MIDI settings are set to output 24 Bits/96kHz and all Mac volume controls are set to MAX. 

The Behringer is connected to the Benchmark via optical. All EQ and other sound adjustments are currently being bypassed.

The Benchmark is connected to the Dynaudios via balanced XLRs. The Dynaudio's EQ settings are all set to flat.

I have a 1/8" to 1/8" cable to calibrate the iMac's internal soundcard.

I assume I should download and install the ECM8000 calibration file from here. I assume I do not need the RS meter?

Since my setup is not like most on here in that it includes all pro-audio gear I'm feeling a little unsure of the connections. Here is what I thought would work once I'm ready to take measurements:

iMac OUT-->optical-->DEQ2496-->optical-->Benchmark-->balanced-->Dynaudios

ECM8000-->balanced-->DEQ2496

Benchmark-->analog out--->iMac IN

Is this going to work or do I need to buy new cabling in order to run analog out of the iMac directly to the DEQ2496 and analog out of the DEQ2496 right back to the iMac? Will having the Benchmark in the chain digitally matter?

Also, my Dynaudios only go down to 50Hz and begin rolling off below that fairly quickly. I still want to measure full-range the speaker/room interaction so should the ECM8000 be oriented horizontally or vertically at the listening position at ear height?

Bill


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

wgb113 said:


> Since my setup is not like most on here in that it includes all pro-audio gear I'm feeling a little unsure of the connections. Here is what I thought would work once I'm ready to take measurements:
> 
> iMac OUT-->optical-->DEQ2496-->optical-->Benchmark-->balanced-->Dynaudios
> 
> ...


 Yeah, it looks like you’re going to have some trouble. Here’s a diagram that shows the correct connection scheme for using an audio interface. (The only difference in your case is that the output signal from the sound card goes directly to the amplified speakers.)












> I assume I do not need the RS meter?


The meter is primarily for the SPL calibration routine. After this calibration, the SPL (vertical) markings on a frequency response graph will have relevance. Otherwise, they’re just arbitrary markings. Valid measurements _can_ be taken without the SPL calibration routine, but since you already have the meter, might as well us it. :T




> I assume I should download and install the ECM8000 calibration file from here.


The generic file is mainly for "FYI" measurements. If you intend to do equalization, I suggest getting your mic calibrated by a lab. As you can see from the graph below, there are significant variations from one mic to the next. You won’t get accurate measurements with a generic calibration file, and you surely don’t want to do any equalizing based on inaccurate measurements










* Variations between ECM8000 microphones*​

Regards,
Wayne


----------



## wgb113 (Jan 12, 2012)

Wayne,

Thanks for the response. So it sounds like I should take the Benchmark out of the equation in order to measure because I have to use analog In/Out of the iMac's soundcard?

As for the SPL meter, the DEQ2496 has one built-in that is used in combination with the EMC8000. Would this not suffice?

Bill


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

Sure, that will work for SPL metering. However, the DEQ isn’t going to work as a mic pre-amp for measurement purposes.

Regards,
Wayne


----------



## wgb113 (Jan 12, 2012)

Wayne,

So I'll need a mic pre-amp. Ideally I can find something with a mic-preamp and MIDI-to-USB interface built in. A soundcard onboard would be a bonus. Looking at the Tascam US-144MKII which seems like it might fit the bill.

Any issue calibrating the iMac's soundcard via analog and then routing a digital signal out to the amps in the Dynaudios?

Bill


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

With the Tascam or something similar, the iMac’s soundcard becomes irrelevant. It won't even be in the signal chain. For the measuring and equalizing, you should stick to signal routing per the diagram above. After that you can reconfigure the system any way that suits your purposes. :T

Regards,
Wayne


----------



## wgb113 (Jan 12, 2012)

Even better! So connections for measurements would be:

iMac-->USB-->Tascam
Tascam-->RCA Out (unbalanced RCA/XLR cable)-->Dynaudios
Tascam-->Mic Out-->ECM8000

If/when the time comes to use some EQ as icing on the cake I'd connect the Tascam to the iMac via USB and to the DEQ2496 via MIDI to load any PEQ settings.

I think (and hope) that I've finally got this right. Looks like I'll be ordering the cabling and unit this weekend rather than measuring.

Bill


----------



## wgb113 (Jan 12, 2012)

*Soundcard Calibration*

So I finally got around to ordering the Tascam and sat down today to calibrate the sound card and I'm getting a whole lot of nothing.

Equipment Involved:
iMac running OSX 10.7.3 (Lion)
Tascam US-144mkII (Driver 2.0, Firmware version 2.01)
REW Version 5.0

I have the iMac connected to the Tascam via USB.

On the Mac:
System Preferences-->Sound-->Output=US144MKII: Output, Input=US144MKII: Input
Audio MIDI Settings-->selected US-144MKII 4in/4out and chose both "Use this device for sound input" and "Use this device for sound output". Under "Input" it shows Clock Source = Hardware, Source = Input, Format = 44.1, 4-ch, 24-Bit Integer. It lists Master volume along with volume for each channel and all are set to minimum and it will not allow me to adjust. All is the same under "Output".

On the Tascam:
24-Bit/44.1kHz
Sample Clock Source: Internal
Digital Input Status: no valid signal
Digital Output Format: S/PDIF
ch1 & ch2 = analog inputs
ch3 & ch4 = digital inputs
LINE OUTPUTS = ch1 & ch2
DIGITAL OUTPUTS = ch3 & ch4

In REW:
Preferences-->Soundcard:
Sample Rate = 44.1
Output Device and Output = Default Device
Input Device and Input = Default Device
Input Channel = Right
Replay Buffer = 32k
Sweep Level = -12dB
Record Buffer = 32k

I have the "LINE OUT" of the Tascam connected to the "LINE/GUITAR IN R" via an RCA-->1/8" analog cable using a 1/4" headphone adapter.

When I hit "Calibrate" in REW and go through the steps, the tone starts playing but the other meters show -129.4dB FS. No matter what knobs I twiddle on the Tascam nothing happens with those meters.

I'm sure it's something obvious but I'm stumped as to why I'm not getting anything on this? When I connect a pair of headphones to the Tascam I hear the tone fine.

Bill


----------



## JohnM (Apr 11, 2006)

Unfortunately Apple's Java runtime has a bug that prevents Java applications accessing the inputs of multichannel soundcards. They show no signs of planning to fix it, a fix may come when Oracle start providing a Java runtime for OS X. In the meantime some users have been able to get the inputs working by using Jack OS X, which can provide a stereo signal that Java apps like REW can access.


----------



## wgb113 (Jan 12, 2012)

So can I use the iMac's internal sound card and the Tascam as a mic preamp?


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

That should work, as long as the Mac’s internal sound card has a *line* input. You don’t need a calibration file for the TASCAM, as it pretty much has ruler-flat response. However, you should probably see if you can generate a calibration file for the Mac’s sound card.

Regards,
Wayne


----------



## wgb113 (Jan 12, 2012)

If I use the Tascam without calibrating it am I going to run into any issues with the whole Apple/Java thing?

Bill


----------



## Wayne A. Pflughaupt (Apr 13, 2006)

They have nothing to do with each other.

Regards,
Wayne


----------



## wgb113 (Jan 12, 2012)

But I thought that the whole reason why I couldn't calibrate the Tascam was due to an Apple/Java conflict? I just want to make sure there's not something else I've missed before moving on to measuring.

Bill


----------



## JohnM (Apr 11, 2006)

Java apps can't access the inputs of the Tascam, whether that is for calibration or measuring or anything else, but REW will be using the line input on the Mac so that doesn't matter.


----------



## wgb113 (Jan 12, 2012)

So after a bit of time away doing other things I finally had some time to sit down and try and measure my room/speaker relationship.

After several failed attempts at trying to get my iMac, Tascam 144mkII, and REW to play together nicely I threw in the towel and got out the Dell laptop and went through the setup and calibration steps again with success!

I was able to make some measurements and it looks like I did everything correctly:

















If everything looks correctly done, can anyone help me interpret these? It seems I can use acoustic trapping to smooth out the peaks @ 265, 220, 120, 110, and 50 Hz with some parametric EQ to further pull them down if necessary.

I'm concerned about the nulls @ 180 and 155 Hz though. Will the trapping help that at all or do I need to experiment more with speaker/listener placement?

I've planned on making "superchunks" for the front two corners that would run floor to soffit, and soffit traps running around the entire room. The soffit on the front wall would be roughly 16" x 16" and the soffits on the other three walls would be 16"D x 9"H.

The room is roughly 11'6"L x 10'W x 9'H with a 40"W a 26"L "entryway" into it. It's a home office that I'm using for a computer-based 2-ch music only setup. Floors are hardwood with an area rug, walls and ceiling are drywall on standard new construction 2x4s. 

The speakers are active monitors by Dynaudio that are only rated down to @ 47Hz. I have no plans for adding a sub as that would create more issues in such a small room.

Any help would be greatly appreciated.

Bill


----------

