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bwaslo 14th July 2007 08:00 PM

freebie Speaker/Room response measuring software
(I've posted similar announcements on other boards, so my apologies if this is old news to anyone reading here)

I posted another audio-oriented Windows software application to the Liberty Instruments' web site.

SynRTA is an RTA-like analyzer that uses continuous noise-like sound (played from a CD), but which doesn't need to "settle" when you measure -- each update of the graph is complete and easily and quickly repeated. It's a new technique (at least as far as I know). I came up with it originally for a different purpse (see "DiffMaker"), but found myself using it a lot for setting up subs and main speakers.

SynAudio was developed for setting up loudspeakers and subwoofers in listening rooms for best frequency response and coverage. The idea was to combine the operating simplicity of an RTA type analyzer with the speed of operation of a synchronous type analyzer.

More at: SynRTA section of Liberty Instruments' site

BlueWizard 14th July 2007 08:21 PM

"A nice thing about using noise is that you can just play it on a CD without having to wire a computer to your sound system. "

Just out of curiosity, where do I get this magic 'noise' CD?


bwaslo 15th July 2007 01:20 AM

>Just out of curiosity, where do I get this magic 'noise' CD?

The program can generate WAV files of it, which you can burn to an audio CD. With a burner and burning software such as Nero. It's pretty easy.

It's not claimed to be magic, BTW, it's just not actual Pink Noise and the program is quite particular about it.

EC8010 15th July 2007 01:07 PM

Just as soon as I've got my new loudspeakers made, I'll try out SynRTA. Thank you for making it available.

I wonder if you can answer an unrelated question, though? I've just made a dinosaur computer specifically to be able to use the Orchid soundcard that your old Liberty Audiosuite needed. It all works, and I've been reminding myself of how to use LAUD, but the ADC section of the Orchid soundcard rolls off -3dB at 50Hz. Can you remember which (and where) are the coupling capacitors that need to be substantially increased in value?

bwaslo 15th July 2007 04:36 PM


Sorry, it's been too long time a time.

You should be able to trace back from the line-in jack to the codec and look for series capacitors (there are probably some resistors there, too). You may also want to check the line output circuit, too, for series caps.

If you can't get it going, I think I have an old Turtle Beach Pinnacle card around still.

EC8010 15th July 2007 06:13 PM


Originally posted by bwaslo
You should be able to trace back from the line-in jack to the codec and look for series capacitors (there are probably some resistors there, too).
Yes, I was just hoping to avoid tracing the board. :rolleyes: Never mind, it's a dirty job, and a man's just got to get on and do it.

The card works fine, so changing the coupling capacitors is a bit of a refinement. The output department doesn't need attention because its coupling capacitors see a higher impedance load (measured 8Hz f-3dB).

PeteMcK 18th July 2007 01:03 PM

first try
2 Attachment(s)
here's my first try of the software, using no-name electret mic into mic input of sound card, (so ignore low end roll off),
red curve is a 2 way i'm still tweeking xover on, woofer goes low but doesn;t have much punch, obviously need to pad down the tweeter a bit more; green curve a 2.5 way which has very solid bass.
Obviously a room problem (perhaps mic placement too?) at ~ 100 and 45-65 hz.

Next step, try higher res and limit graph to problem areas, try unblocking the ports on the mid/bass of the 2,5 way.

Many thanks to bwalso for SynRTA, very easy to use (even if I'm not following the instructions to the letter...:-)

Pete McK

Pano 19th July 2007 06:07 AM

Thanks for posting this!

I was wanting to do some speaker RTA this morning and couldn't find a software I liked. Then Voila! SynRTA.

Spent a good bit of time with it. Seems to work well, even on my antique computer. I used the 1/12th octave measurement. Generated a 10 minute pink noise wave and burned it to CD. 3 times the same track on the CD for 30 minutes play.

At first the graph looked "noisy" even with no input. Took me awhile to figure to kill the right channel input, as the left channel was my only input. With the windows mixer balance control all the way left, no more worries. I love the way the software pops open the Windows volume control. Neat!

The CurveHold function is great. Works like a charm. Also a nice touch to be able to label the curves. The Reference function takes some gettting used to, but it's a great feature. I showed me very clearly an FR kink that my Altec horns had on the baffle. Showed me how much the kink could be killed by putting towels around the horn mouth. Sweet! Now I know what to look and listen for when working on this problem. It wasn't a small problem, but hard to find. SynRTA showed it to me right away as well as how much effect my homemade cures had.

Overall a great piece of software. And it's free!

Only one little gripe so far. I never install programs on my C: drive, but the installer didn't give me a choice. No big deal, the program is small and installs in a flash, but I'm used to having a choice. =)

PB2 15th June 2008 01:18 AM

Been trying this out and it is very nice, thanks Bill!

Will it take advantage of a 96K sample rate card as I'd like to test at least to 25K, if not higher? I have LAUD also, but I want a portable system that will run on a Laptop, and LAUD requires that special ISA sound card.

Just to confirm, this is like an MLS test but without the time windowing to remove the room reflections, or did I misinterpret the description?

Bill, do you have a preference as to where to post questions?

Thanks in advance,
Pete B.

PB2 17th January 2010 02:26 AM

I did look under help for these features, did I miss them?

Sure would be helpful if you didn't have to load the .cal file every time the program is started. Even if it is a hard coded file name for example.

Would also be helpful to have it start up with a saved reference file so that when doing measurements against a standard it doesn't have to be loaded up each time. This too could be a fixed file name if necessary.

I suppose one could just use sleep mode on a computer to "save" everything, but these two features would be better.

Pete Basel

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