Help with Hardware Setup to Use ARTA to Measure Speaker FR

[ChrisNC]

Hi. I have searched but haven't found what I am looking for. I would like to measure the frequency response of my speakers (and eventually the speaker/room to help with placement) and am having trouble with the hardware setup.

At the moment, I have settled on ARTA, and I am looking to set it up for dual channel measurement as depicted in Figure 1.5 of the User Guide.

I have a Dell laptop so I am planning to use a Sound Blaster X-Fi HD external sound card (it seems to be one of the few that has RCA inputs and outputs) and a calibrated Dayton EMM-6 from Cross Spectrum. I will make or have someone else make a voltage probe.

What I need help with is the mic preamp and its connection to the sound card. I can find any number of preamps (e.g., the Art USB Dual Pre Project Series). They seem to all have 1/4" outputs and most (or all?) of those are balanced. So I either need a mic preamp with phantom power that has rca outputs, or I need to know how to take the output from a 1/4" output to the left RCA input of the sound card. Can I just use a 1/4" to rca cable even though the output is balanced? (I assume not.) Do I need to find a preamp with unbalanced outputs? Something else? Any recommendations for preamps and methods to hook up the preamp to the sound card are greatly appreciated.

Thanks.

Chris

[hongrn]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Chris, take a look at this so you have an idea of how to hook up your measurement system:

http://soundhobby.com/measurementsystem.htm

I currently use this Rolls mic preamp for my Cross Spectrum EMM-6:

http://www.parts-express.com/rolls-m...power--245-032

Hong

[Chris Roemer]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

I use a "Blue Icicle".

[1100xxben]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

I've never used the Art USB Dual Pre, but I'm pretty sure it is a USB audio interface with microphone preamps built in. In other words, when you plug the USB into your computer, it will act as your sound card and there's no need for the X-Fi. The only thing you'll have to do is adapt your 1/4" balanced outputs to RCA, which is easy... Tie the 1/4" tip to the RCA tip, and the 1/4" sleeve to the RCA sleeve. The ring connection on the 1/4" output will be left floating. What kind of amplifier will you be using?

EDIT:
After looking at it again, it appears the USB pre is only input, and not output. Still, the audio can go into your computer via the USB, so there's no need to hook it to the sound card if you use the USB, or you can do it as I explained above. Instead of buying the X-Fi and the USB Pre, you could get something like THIS and it will provide 48V Phantom power, a mic preamp with audio directly into the USB connection, and 1/4" balanced outputs. The balanced outputs can be hooked up to RCA as I explained above.

[donradick]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

So, bottom line -

If you want a super easy measurement system, get a blue icicle and Arta.
For me absolute SPL / voltage measurements is not that critical.

If you want to produce the extra goodies with dual channel, get one of those Rolls mike preamps that Hong linked to.

BTW, if you don't know already, Charlie Laub put together a fantastic guide: Here

First link is the PDF.

Have fun! Measurements open a whole new door on the process and science.

[ChrisNC]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Thanks for the quick responses. Much appreciated. I think I am making progress thought I have some follow-up questions. I am not wedded to the preamp I mentioned. It was in someone's "suggested equipment" list. At the moment I am planning to use one of my Quad amps (either 405-II or 606).

Hong, I had seen your web site, thanks. It helped me get as far as I got. The mic preamp you are using just might fit the bill. It looks like it has an unbalanced 1/4" output. I am assuming that I could then just use a 1/4" to RCA cable such as http://www.parts-express.com/peavey-...able--241-5676. Does that sound right to you guys?

1100xxben, Thanks for the info on how to deal with the balanced connection. Will explore if I have to go that route. Was there supposed to be a link with the THIS? Would the preamp Hong mentioned (http://www.rolls.com/product.php?pid=MP13) do the trick?

donradick,I do want the dual channel. I saw the guide Charlie Laub put together - that's how I ended up here! :-)

At this point, it looks like the external sound card, mic and the Rolls pre should work. Let me know if I am wrong.

Thanks again.

Chris

[1100xxben]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Was there supposed to be a link with the THIS?

oops, yes... it was supposed to be THIS

[Pete Basel]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

I plan to use the discontinued EMU-0202, that has one XLR mic input that I think will work well:
http://www.sweetwater.com/store/detail/0202USB/

It tests very well here:
http://www.libinst.com/EMU%200202%20USB.htm

More:
http://techtalk.parts-express.com/sh...RTA-and-laptop

[rhodesj]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Why not use a USB mic like the UMIK-1? No preamp or sound card needed. I got the Cross Spectrum Labs calibrated one, and am completely happy. I've used it with REW to measure and EQ subs and speakers.

[Pete Basel]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

You can also measure electronics and crossover electrical responses if you have line in and
the suggested cables to protect it with an external or built in DAC.
The USB mic is nice when you just want to do acoustical measurements.

[johnnyrichards]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

You can also measure electronics and crossover electrical responses if you have line in and
the suggested cables to protect it with an external or built in DAC.
The USB mic is nice when you just want to do acoustical measurements.

Precisely why I use the USB Dayton mic, I am just interested in doing acoustic measurement.

[johnnyrichards]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

So, bottom line -

If you want a super easy measurement system, get a blue icicle and Arta.
For me absolute SPL / voltage measurements is not that critical.

If you want to produce the extra goodies with dual channel, get one of those Rolls mike preamps that Hong linked to.

BTW, if you don't know already, Charlie Laub put together a fantastic guide: Here

First link is the PDF.

Have fun! Measurements open a whole new door on the process and science.

SPL accurate can be accomplished fairly simply with an SPL meter and some fiddling with either the mic settings or just doing an adjustment to the level on the FR window ie add or subtract 33.2db. Most SPL meters are going to be reasonably accurate enough to get you very close to SPL accurate.

To my knowledge it is difficult if not impossible to do a true SPL accurate set up with a USB mic for an input and an internal sound-card for the output.

[tmhutson]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

I have the USB dual pre. Works great. I use the headphone out to my stereo.
I could use the 1/4" output if I wanted to.
I can use it for other things as well (I have a synth and have it plugged in).

[ChrisNC]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Thanks very much for all of the suggestions. Looks like I have some further research to do. The option of measuring electronics and crossovers is appealing. If nothing else it makes it easier to rationalize the purchases!

Best,

Chris

[jsr]

Re: Help with Hardware Setup to Use ARTA to Measure Speaker FR

Does a laptop's headphone 3.5mm jack work while using the USB also? My laptop has a combined mic/headphone jack and I'm wondering if I can use that for the excitation signal with a UMM6 plugged into the USB for response measurement. Simpler setup.