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Author Topic: Reasonably priced RTA software system  (Read 24542 times)

Mac Kerr

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Re: Reasonably priced RTA software system
« Reply #10 on: February 14, 2012, 12:48:49 am »

I didn't say it prevents accuracy. It could definitely hinder accuracy if the latency is to large, I think you could agree with that.
Firewire interfaces tend to have lower latency.

Latency has no impact on time offset measurements, nor on any other aspect of dual FFT analysis. It is cancelled out by the nature of the measurement system.

Mac
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Mac Kerr

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Re: Reasonably priced RTA software system
« Reply #11 on: February 14, 2012, 12:52:31 am »

If Smaart has tested it and trusts it then so would I, actually I do trust it.

What Jamie anderson of Rational Acoustics uses for his interface in his Smaart training sessions is a USB interface Roland OctaCapture. That is where I first found out about it. I have been using it in my measurement system for about a year.

Mac
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Clayton Ganzer

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Re: Reasonably priced RTA software system
« Reply #12 on: February 14, 2012, 01:38:55 am »

What Jamie anderson of Rational Acoustics uses for his interface in his Smaart training sessions is a USB interface Roland OctaCapture. That is where I first found out about it. I have been using it in my measurement system for about a year.

Mac

And James Woods, Rational Instructor, of Rational Acoustics uses Presonus Firebox and the Firepod.
Jamie Anderson does talk about some signal level discrepancies between the interface and the software that has caused him some problems with the OctaCapture.

I think they are both great interfaces. It seems like on their forums there is the general consensus that the Presonus and Motu stuff is considered a step above the USB stuff. Its just like your laptop video card sharing the system memory or having dedicated system memory. Your video card will perform better with dedicated memory, just like the firewire can provide better performance due to its dedicated chip.
I am happy that your Roland OctaCature as worked flawlessly for you, as it should and is intended to do, but I continue to hear people have more complaints and problems with USB interfaces, everyone always wants to 'upgrade' to firewire.
Yes firewire is becoming more and more rare to find on new computers, and the ability to add expansion cards to laptops is becoming less also, so its not like you can add a firewire port to your laptop as easily (or at all in most cases) like you could before.
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Curtis H List (Too Tall)

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Re: Reasonably priced RTA software system
« Reply #13 on: February 14, 2012, 11:35:20 am »


snip

I am happy that your Roland OctaCature as worked flawlessly for you, as it should and is intended to do, but I continue to hear people have more complaints and problems with USB interfaces, everyone always wants to 'upgrade' to firewire..

We have versions USB 1 and USB 2 and USB 3.
I think some of the problems might be lurking here.

If you have a process that requires high through-put and you are plugged into a USB 1 port the  program may screw up.
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TJ (Tom) Cornish

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Re: Reasonably priced RTA software system
« Reply #14 on: February 14, 2012, 03:11:18 pm »

I didn't say it prevents accuracy. It could definitely hinder accuracy if the latency is to large, I think you could agree with that.
Firewire interfaces tend to have lower latency.
Nope - the few milliseconds of latency of even the worst interfaces dwarf in comparison to the acoustical latency of the room you're measuring, which is compensated for in measurement.
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Paul Tucci

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Re: Reasonably priced RTA software system
« Reply #15 on: February 14, 2012, 08:19:35 pm »

I didn't say it prevents accuracy. It could definitely hinder accuracy if the latency is to large, I think you could agree with that.
Firewire interfaces tend to have lower latency.

I sense a teachable moment for some that may be following along.

Let's address the concern of a large latency hindering accuracy. Clayton seems to be suggesting that something could slip through the measurement setup if the interface has a long throughput time. Typically, an interface's A/D converter has a few milliseconds of throughput delay. I haven't measured my USBPre in a decade or so but I'll guess it sits right around there also.

The question becomes " Can we accurately measure something that happens faster than the length of this latency?"  Logic would tell us that one needs an action before its associated reaction can take place. The call preceeds the response. The effect follows cause. So it's reasonable to say 'No, we can't measure that."

What's being left out of that thought is a suspension of serial time during the measurement proicess.

Let's look at a hypothetical Impulse Response measurement because we're trying to find the proper offset delay for the delay stack.  We're asking "How much time does it take for my audio to get back here to my delay stack?" Signal leaving the console is the Reference side of the measurement, a microphone's output, placed at the appropriate seat in the delay zone, is the Measurement side of the equation.

A really low  latency device measures the difference in arrival time as 200 mSec.
A really high latency device measures the difference in arrival time as 200 mSec.

BECAUSE...

both the reference and the measurement signals are travelling through the device's latency. The difference in arrival time is what counts, not the arrival time of the measurement side of the equatiuon. Even if the latency of  device is an hour, the difference would remain the same because both sides of the measurement are equally affected by it. An hour and 200 mSec (arrival time of the mic) minus and hour (arrival time of the console output) is still 200 mSec.

While this hypothetical device's latency  would interfere with one's workflow, the latency of real world interfaces is a non factor.

PT
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John L. Murphy

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Re: Reasonably priced RTA software system
« Reply #16 on: February 28, 2012, 12:58:33 pm »

Hello all!

I am looking for reasonably priced RTA software, USB interface and a measurement mic.
I can't stretch to the $895 for the Smaart software at this point but need something to do analysis of rooms & speaker systems in those venues.

Suggestions?

Phil
Canadian Event Production Services
www.caneps.com

Hi Phil,

Please take a look at my TrueRTA software at the link below. TrueRTA (Level 4) is a 1/24th octave RTA software app for Windows which sells for $99.95. It includes RTA, signal generator, oscilloscope and dB meter. You can use it with any good audio interface. In addition to traditional pink noise testing I also provide "Quick Sweep" a swept sine wave (short log sweep) test which provides a good alternative to pink noise testing. The one octave version of the analyzer is free and never expires. I remember well using a one octave hand held analyzer to check the response of concert sound systems in the late 1970's. When the 1/3rd octave hand held analyzer became available we added it to our toolbox. These were very pricey analyzers back then and I always wished I could have one handy all the time. My personal history with handheld (hardware) RTA's is what led me to develop my TrueRTA software app. I needed a good RTA for my own use. In software I can vary the resolution and so I provide all the standard resolutions ranging from 1 octave to 1/24th octave. Here is a link:

http://www.trueaudio.com/

Combining the software with a good USB audio interface (such as the Tascam US 122 or similar) and your existing PC notebook provides a portable but powerful audio testing capability with only a modest investment.

For inexpensive measurement mics I recommend:

Dayton Audio EMM-6 (around $40)
Behringer ECM8000 (around $55)
Audix TM1 (around $300)

I apologize to anyone offended by the commercial nature of this post.

Regards,

John
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John L. Murphy
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Bruce Olson

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Re: Reasonably priced RTA software system
« Reply #17 on: May 08, 2012, 06:06:06 am »

I am looking for reasonably priced RTA software, USB interface and a measurement mic.
I can't stretch to the $895 for the Smaart software at this point but need something to do analysis of rooms & speaker systems in those venues.

Suggestions?

You can DL the free demo of Systune at http://systune.afmg.eu/ which gives you an RTA along with a signal generator and SPL meter, or get a real Dual FFT measurement system from AFMG for $525 by going to the store at http://store.afmg.eu

Bruce
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Bruce C. Olson
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Douglas R. Allen

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Re: Reasonably priced RTA software system
« Reply #18 on: May 12, 2012, 11:03:25 am »

This is exactly what you asked for all in one package. Includes a microphone for $300 and tax.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-790&FTR=390-790

This was designed for Parts Express by Bill Walso, author of Praxis, LAUD and other well regarded audio analyzer solution.

I use Praxis (just under $1k) and OmniMic will not do everything it will, but it covers a lot of functions in a very tight package.

DisClaimer: I have not used the OmniMic so I do not know if there are things missing you MUST have. From what i have read it looks like it gives you what you need for a very fair price. It looks so well thought out I have considered buying it for convenience (And I am a window-shopping Gear Slut)

Curtis;

I looked at this awhile ago. If I remember right it has no phase view? Has this changed?
I'm heading to the link but I'm pretty sure there is no phase screen to view.

Douglas R. Allen
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Re: Reasonably priced RTA software system
« Reply #18 on: May 12, 2012, 11:03:25 am »


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