In Room/Speaker measurement rig - What to buy?

JohnR · « **Reply #20 on:** 11 Jul 2012, 01:58 pm »

I can't tell from your description what length you need to reach... better to be too long than too short.

I'd still advise confirming that the outputs don't mind having one side of the balanced output shorted to ground. I'd assume it's OK if it were my unit, but it's not, soo....

Dr.Cmnsky · « **Reply #21 on:** 11 Jul 2012, 05:18 pm »

John, thanks for the response, but I wish i understood it completely.

Can you elaborate on "I'd still advise confirming that the outputs don't mind having one side of the balanced output shorted to ground. I'd assume it's OK if it were my unit, but it's not, soo...."

JohnR · « **Reply #22 on:** 11 Jul 2012, 05:33 pm »

Oh, well, the outputs on most of these units (and other "pro" gear) is balanced. The 1/4" socket is a TRS aka "tip ring sleeve" type, with ground, positive, and negative signals. Like this (bottom half of page):

If you plug in a mono jack (a "TS" type i.e. "tip sleeve") then the "ring" will be shorted to ground. I assume that most pro gear is designed to deal with this. For example, the manual of the 2i2 that I'm messing with now says "Either 1⁄4” TRS (balanced) or TS (unbalanced) jack plugs can be used."

I'm being cautious - I don't want to advise you to plug in a TS jack into the balanced TRS outputs. I'm doing it right now, with the 2i2. But the manual says I can do it...

JohnR · « **Reply #23 on:** 11 Jul 2012, 05:38 pm »

The two different types of connector:

(from http://en.wikipedia.org/wiki/TRS_connector)

JohnR · « **Reply #24 on:** 11 Jul 2012, 05:41 pm »

BTW you made a good choice to go with longer analog cables and shorter USB cable. The 4m USB cable I normally use doesn't work with the new interface...

Dr.Cmnsky · « **Reply #25 on:** 11 Jul 2012, 06:36 pm »

I just checked the soundcard, so if I'm understanding correctly I'm looking to buy is "Dual 1/4 to RCA TRS" cables?

andy_c · « **Reply #26 on:** 11 Jul 2012, 07:04 pm »

Quote from: Dr.Cmnsky on 11 Jul 2012, 06:36 pm

I just checked the soundcard, so if I'm understanding correctly I'm looking to buy is "Dual 1/4 to RCA TRS" cables?

I've got an M-Audio MobilePre, which has balanced 1/4" TRS outputs. Here's what I did, which avoids shorting one side of the balanced output to ground.

1.5 ft. long 1/4" TRS cable for the loopback connection (REW phase reference)
6 ft. long 1/4" TRS cable for the main sound card output signal (longer if needed)
One of these adapters to adapt the 1/4" TRS male at the end of the cable above to a 3.5mm TRS male
One of these to adapt the 3.5mm plug to a pair of RCA connectors

Output is taken from the left-channel RCA (the white one), which now carries the "hot" of the sound card's balanced output. To be safe, put masking tape over the right-channel RCA plug (the red one) so it doesn't short on anything. This is the "cold" of the balanced output of the sound card, which is now left open, not shorted to ground as other alternate configurations do.

In addition, you'll probably need an RCA "y cable", having an RCA jack on one side, going to a pair of RCA plugs at the other. This will connect to the white RCA plug described above, putting the same input into both the left and right channels of your audio system.

andy_c · « **Reply #27 on:** 11 Jul 2012, 07:28 pm »

Here is a pic of the arrangement (without the RCA y cable). The red RCA connector gets taped up and is not connected to anything. The white one gets connected to the RCA y cable (not shown) to apply the same signal to both the left and right inputs of your audio system.

JohnR · « **Reply #28 on:** 11 Jul 2012, 07:35 pm »

Might be easier to use a pair of these and a regular RCA cable

http://www.ebay.com.au/itm/HOSA-YPR-102-Stereo-1-4-TRS-M-Dual-RCA-F-Adaptor-Y-Cable-NEW-/390438795406?pt=LH_DefaultDomain_0&hash=item5ae7f7388e#ht_1910wt_1347

JohnR · « **Reply #29 on:** 11 Jul 2012, 07:37 pm »

Or - just use a mono cable, because :

"You can use either TRS or TS connections from the monitor outputs".
Therefore a standart TS-RCA connector/adapter will be fine (unbalanced).

https://getsatisfaction.com/smug/topics/art_usb_dual_pre_what_cables_to_connect

andy_c · « **Reply #30 on:** 11 Jul 2012, 07:42 pm »

Yes, that's another way. Since the cal requires that the sound card output be connected to its input, I just disconnect the adapters and use the TRS cable.

Edit: I see that ART has confirmed that it's okay for one of the balanced outputs to be shorted, then using an unbalanced cable will be fine.

Dr.Cmnsky · « **Reply #31 on:** 12 Jul 2012, 01:29 am »

OK, here goes nothing!

I'm going to buy

Hosa YPR102 TRS Male To Dual RCA Female Y Cable
http://www.amazon.com/Hosa-YPR102-Male-Female-Cable/dp/B000068O4W/ref=sr_1_8?ie=UTF8&qid=1342056403

1 Male To Male RCA cable
http://www.amazon.com/Tsunami-RCA701-20-Male-Cable-feet/dp/B003MDJH5Q/ref=sr_1_2?s=musical-instruments&ie=UTF8&qid=1342056486

Does this sound right? Im sorry for all of the questions. Thanks again.

JohnR · « **Reply #32 on:** 12 Jul 2012, 05:10 am »

That should work

Dr.Cmnsky · « **Reply #33 on:** 16 Jul 2012, 03:16 pm »

Thanks. I purchased those. My Mic arrived as well

[edit] searched online and found this guide[/edit]

http://www.hometheatershack.com/forums/spl-meters-mics-calibration-sound-cards/10001-rew-cabling-connection-basics.html

Dr.Cmnsky · « **Reply #34 on:** 16 Jul 2012, 11:30 pm »

The Behringer mic doesnt have the same thread as my Samson boom stand. Both ends are also female. If there was an adapter, I surely lost it.

Does anyone know a good/simple measurement how-to guide?

JohnR · « **Reply #35 on:** 17 Jul 2012, 12:45 am »

Bit of a mystery on the mic stand... got a picture?

This article might help - let us know if you get stuck

http://www.realtraps.com/art_measuring.htm#3

Dr.Cmnsky · « **Reply #36 on:** 17 Jul 2012, 01:14 am »

I tried REQ, but ran into a error stating I had too much over-head during the sweep. Something like 40DB. I'll read the guide and hopefully get somewhere tomorrow.

Thanks again, I'll post pictures tomorrow. Hopefully will come up with a guide for other noob enthusiasts in the future.

56oval · « **Reply #37 on:** 17 Jul 2012, 02:01 am »

Quote from: JohnR on 11 Jul 2012, 01:14 pm

Thanks for the vote of confidence I've decided to structure it as a series of reviews of each item, as doing complete tutorials will be too time-consuming, esp. if it has to be done for two platforms.

With some initial test done, I'm impressed by the Focusrite Scarlett 2i2. Here are the loopback responses for 44.1, 48, and 96 kHz sample rates. At 96 kHz, it's basically ruler flat from 10 Hz to 40 kHz.

The MOTU and the Focusrite are two completely different types of unit. I didn't realize it when I bought them... so long ago, like yesterday? As usual, you can't have your fish and your kettle in the same pot at the same time.

Morning John

So would the Scarlett 2i2 be the better buy over the MOTU .

Cheers

JohnR · « **Reply #38 on:** 17 Jul 2012, 08:01 am »

Quote from: Dr.Cmnsky on 17 Jul 2012, 01:14 am

Hopefully will come up with a guide for other noob enthusiasts in the future.

Working on it now

JohnR · « **Reply #39 on:** 17 Jul 2012, 08:05 am »

Quote from: 56oval on 17 Jul 2012, 02:01 am

So would the Scarlett 2i2 be the better buy over the MOTU .

G'day Mal, I hesitate to answer unequivocally as a. they have different functionality and b. I'm still evaluating them. However for measurements the 2i2 so far is looking pretty good. I've had no issues running loopback tests on XP SP3 and Win7/64 using REW and ARTA so far. HolmImpulse seems a little trickier.