Can simple crossover be designed w/ software + RS SPL meter?

morbo · 24th November 2004, 08:10 PM

I am trying to do a design for a widerange driver (TB 871) crossed to a woofer (Dayton RS 225) that has decent response to 1.5khz or so. I have access to LSPCad 5, but for measurement equipment, only have an RS SPL meter and a multimeter. Can I design a simple, good sounding crossover in the 200-500hz range using these tools?

BillFitzmaurice · 24th November 2004, 08:56 PM

Download an RTA program like the one at the Allen-Heath site, you can use the RS meter as a mic, it's accurate enough in that freq.range, then you can see what different components do in real time as you swap them.

morbo · 24th November 2004, 09:18 PM

Thanks for the suggestion Bill. How do you hook the RS SPL meter up to your computer though? Or do you measure and then manually enter values like in the parametric EQ spreadsheets I've seen?

BillFitzmaurice · 24th November 2004, 09:48 PM

The RTA has a pink noise source built in, the meter simply plugs from its RCA output into the computer soundcard. It's a very simple and easy to use rig, and within the midrange is adequately accurate. For the ten bucks or so the download costs a very useful tool.

cjd · 24th November 2004, 10:06 PM

I have also successfully used my SPL meter with Speaker Workshop for measurements. And Speaker Workshop is free. But it's a bit of a pain to get set up for measurements.

I finally realized I was probably not going to build a mic and pre, and sprung for a Behringer mic. With the rebate going right now, not a bad deal.

C

BillFitzmaurice · 24th November 2004, 10:39 PM

Speaker Workshop is nice but the required interface is a chore. The A-H RTA doesn't have the level of sophistication of SW but for crossover design and basic frequency response charting on the cheap it's very worthwhile and user friendly.

morbo · 24th November 2004, 10:55 PM

Ok well I will be trying this then, or some other similar RTA software, thanks a lot for the tips! If I had known the Ratshack meter was useful for this kind of thing, I'd have started fiddling a long time ago

Has anyone been able to get useful measurement files that could be exported to something like LSPcad using such software and the RS meter? I've tried speaker workshop and the need for a jig, plus the interface really turned me off.

kelticwizard · 26th November 2004, 06:06 AM

Radio Shack SPL meter comes in different models, even different analog models.

The response curve for the mic of various models is given here. So you can take these into account when measuring.

http://www.gti.net/wallin/rsmeter.htm

ergo · 26th November 2004, 07:14 AM

Morbo,

If you can use LspCad then you can also use JustMLS that comes with LspCad. I have made all my project measurements with JustMLS and it works just fine.

With RTA type measurement you can not get acceptable results to import into LspCad. You will not have phase data and impedance mag + phase data. Also The freq response will be polluted with room reflections.

Check

measurements

crossover

Ergo

morbo · 26th November 2004, 11:03 PM

thankyou kelticwizard and ergo, I will use the correction files and see if I can't get up and running using the RS SPL meter in JustMLS. I presume I want to do this with the drivers mounted in the boxes (or is just the baffles ok?), but do I place the mike nearfield (6"?) or in the listening position? Maybe I should just get off my butt and start reading the manuals

24th November 2004, 08:10 PM	#1
morbo diyAudio Member Join Date: Sep 2004 Location: Guelph, Ontario	Can simple crossover be designed w/ software + RS SPL meter? I am trying to do a design for a widerange driver (TB 871) crossed to a woofer (Dayton RS 225) that has decent response to 1.5khz or so. I have access to LSPCad 5, but for measurement equipment, only have an RS SPL meter and a multimeter. Can I design a simple, good sounding crossover in the 200-500hz range using these tools?

26th November 2004, 06:06 AM	#8
kelticwizard diyAudio Member Join Date: Sep 2001 Location: Connecticut, The Nutmeg State	Radio Shack SPL meter comes in different models, even different analog models. The response curve for the mic of various models is given here. So you can take these into account when measuring. http://www.gti.net/wallin/rsmeter.htm __________________ "A friend will help you move. A really good friend will help you move a body." -Anonymous

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24th November 2004, 08:56 PM	#2
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	Download an RTA program like the one at the Allen-Heath site, you can use the RS meter as a mic, it's accurate enough in that freq.range, then you can see what different components do in real time as you swap them.

24th November 2004, 09:18 PM	#3
morbo diyAudio Member Join Date: Sep 2004 Location: Guelph, Ontario	Thanks for the suggestion Bill. How do you hook the RS SPL meter up to your computer though? Or do you measure and then manually enter values like in the parametric EQ spreadsheets I've seen?

24th November 2004, 09:48 PM	#4
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	The RTA has a pink noise source built in, the meter simply plugs from its RCA output into the computer soundcard. It's a very simple and easy to use rig, and within the midrange is adequately accurate. For the ten bucks or so the download costs a very useful tool.

24th November 2004, 10:06 PM	#5
cjd diyAudio Member Join Date: Jun 2004 Location: Windy City	I have also successfully used my SPL meter with Speaker Workshop for measurements. And Speaker Workshop is free. But it's a bit of a pain to get set up for measurements. I finally realized I was probably not going to build a mic and pre, and sprung for a Behringer mic. With the rebate going right now, not a bad deal. C

24th November 2004, 10:39 PM	#6
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	Speaker Workshop is nice but the required interface is a chore. The A-H RTA doesn't have the level of sophistication of SW but for crossover design and basic frequency response charting on the cheap it's very worthwhile and user friendly.

24th November 2004, 10:55 PM	#7
morbo diyAudio Member Join Date: Sep 2004 Location: Guelph, Ontario	Ok well I will be trying this then, or some other similar RTA software, thanks a lot for the tips! If I had known the Ratshack meter was useful for this kind of thing, I'd have started fiddling a long time ago Has anyone been able to get useful measurement files that could be exported to something like LSPcad using such software and the RS meter? I've tried speaker workshop and the need for a jig, plus the interface really turned me off.

26th November 2004, 07:14 AM	#9
ergo diyAudio Member Join Date: Mar 2001 Location: Tallinn, Estonia	Morbo, If you can use LspCad then you can also use JustMLS that comes with LspCad. I have made all my project measurements with JustMLS and it works just fine. With RTA type measurement you can not get acceptable results to import into LspCad. You will not have phase data and impedance mag + phase data. Also The freq response will be polluted with room reflections. Check measurements crossover Ergo

26th November 2004, 11:03 PM	#10
morbo diyAudio Member Join Date: Sep 2004 Location: Guelph, Ontario	thankyou kelticwizard and ergo, I will use the correction files and see if I can't get up and running using the RS SPL meter in JustMLS. I presume I want to do this with the drivers mounted in the boxes (or is just the baffles ok?), but do I place the mike nearfield (6"?) or in the listening position? Maybe I should just get off my butt and start reading the manuals

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