Two out of three problems lately have been cabling problems.

RPlusD is better partly because it is sensitive to cabling errors. ETF and other analyzers will not show a defect if the left and right are reversed or shorted into one. Measurement error can result.

Hi Doug,

I'm a bit of a novice with all this sound measurement stuff, so please forgive my ignorance.

I'm using the latest version of R+D to attempt to measure my room. Everything seems fine, except whenever an Ab bass-note sounds. The room reverberates to this note and the tone swells until another note replaces it. I'm guessing this is the resonant frequency of the room.

My problem is that although I've bought and downloaded the software, watched the videos and sucessfully taken measurements, the whole thing is way over my head. I'm trying to follow what I need to do with the results and how I make sense of the readings and I'm afraid I'm utterly lost.

Is there any way a novice like me can make sense of this? In other words, is there an idiots guide for this software, or is there no hope for me?!

More to the point, if I can eventually make sense of the readings, I can't see how this will help me tame the errant bass note frequency in my room. Move the speakers and re-perform the tests? Add more bass treatment?

Kind regards

Geoff

I will be producing a PDF document on EQing that will explain more about what a resonance is and how to correct for it.

You should watch the videos again and read the app notes agin - its all in there but with technical documents like this you may have to read it a few times before you get the idea.

I ususally read tech documents about five times, even after I have the idea to make sure I understand everything.

I recommend version 1.0.34 of R+D. It solved most of the calibration problems I had.

Btw, Doug, if the channels are reversed in ETF, you will get a sample and a FR plot, but the plot will be *upside down*. It's not immediately apparent that something is wrong.

Posted on AVS Forum in Audio Theory section:

Need loan of a calibrated mic - Atlanta area

I've been doing some work with Doug Plumb of Acousticsoft (author of ETF) on his new R+D project. He'd like me to take a series of measurements of a couple of my speakers. Unfortunately I don't have a calibrated microphone, just the Radio Shack meter which doesn't have the response needed for this type of measurement.

Can anyone loan me a calibrated mic (and power supply/preamp if it needs one) for a couple days? I'll pick it up within a reasonable distance. Please PM me.

Thanks in advance.

I want to do a PDF file that shows aspects of DSP EQ as applied to room acoustics & loudspeakers.

DMF has some Klipsh horn loaded speakers that I would like to measure and write about in the PDF file. I need these measurements to be calibrated so would appreciate anyone lending him a mic. Its impractical to ship it from here both ways.

DMF: what you say about the cables is true if you get them mixed up at L & R input. If you get them wrong at the outputs then the error will not appear in ETF but will in RPlusD.

Um, I downloaded this program on my PC and now I am not getting any sound from my computers speakers. The device manager says its "working properly."

What happenned. What could I have done???

Nevermind. I freaked out there for a minute and thought I had fried my soundcard. Thanks to system restore.

Doug-

Is there any way in RPlusD to use a gate time smaller than 1ms?

/jim

Hello soundthinker,

The minimum gate time is set at 1 ms. is there a reason why it should be less ?

Doug-

In many studio situations there are first reflection points that fall under 1ms. (Console, LCD monitors etc) It's helpful or at least informative to be able to look at the response without these reflections.

/jim

Oundthinker:

"Keep telling the same lie over and over and they'll end taking it for truth..."

Hermann Goering, second in command of the Third Reich

Hello Ethan, Doug, and everyone else,

I purchased ETA’s software and Doug informed me about R+D so that is installed as well. I’m a little mystified by how I go about achieving what I need. Here’s what I’d like to do:

Run tests to take of “picture” of the room before any bass trapping

Place my monitors in the best location for the smoothest response

Place my new subwoofer for the smoothest response

Determine the problem areas in the room to place the panel traps

Model EQ adjustments for final EQ tweaking of room

My situation:

16’ x 13’ 4" x 8’ room (give or take a ½ inch)
4” 703 in frames placed by using the mirror trick
R+D software
Behringer ECM8000 test mic
Event 2 way, 8” woofer powered monitors
KRK 150 watt sub
Behringer Ultra Curve

The questions:

How do I go about taking the initial measurements? Do I run a measurement with the mic in 20 different random locations?

After determining where my listening location is by using the 38% rule, how do I perform tests to optimally place my monitors on the equilateral triangle?

How do I run test to place the sub. (I think I’ve found the info on this on Doug’s site)

How do I organize the whole process in the proper order to achieve the best end result?

I know this is a tall order but I’m pretty confused regarding how to proceed. I’ve watched the videos several times and have been reading any documentation over and over again to acquaint myself with this and my understanding is improving. Any input as to how proceed would be a great help however.

Thanks for any and all input.

Lee Knight

Lee,

I was hoping Doug Plumb would reply, but in the mean time I don't want you to feel ignored!

> How do I go about taking the initial measurements? Do I run a measurement with the mic in 20 different random locations? <

From what you describe I'd do all tests at the listening position.

> After determining where my listening location is by using the 38% rule, how do I perform tests to optimally place my monitors on the equilateral triangle? <

You put the speakers about where you think they should go, then measure. Then slide them along the axis as shown in the drawing below and measure again. Repeat until you find the place where the bass response is flattest.

> How do I run test to place the sub. <

Same as above - measure, move, measure, move, and so forth. Hopefully it won't be as overwhelming as you fear.

--Ethan

Hello Lee,

I don't check this as often as I should but if you send me a question by email I will answer.

Ethans response is accurate.

Many users have subwoofers. Placement of these is outlined in one of the posted PDF documents.

I would suggest everyone read the FrequencyResponse.PDF document.

I really like some of the signatures I'm seeing on here, particularly with reference to Goring.

I have spent a fair amount of time reading about the bankers.

For interested people, watch the video The Capitalist Conspiracy. Its on Google Video. That shows how the world works. Also The Creature From Jekyll Island should be read by everyone.

I've been too busy to run my tests but it looks like I'll get a chance to begin tonight so...

What's a good SPL for the test signals?

85dB SPL?

A or C?

Keep the SPL low - 80 dB or so, try two measurements with mic at the same place. is the measurement repeatable ? If not increase SPL.

Thanks Doug. Will do.

To be clear, the RplusD demo is only functional enough to test the compatability of(with) your soundcard ?
Is this correct?

(I'm waiting on da check, man)

That si correct. The functionality of RPlusD only lets you check the operation of your sound card and hardware.

It shows an impulse response for this.

I have just added a pseudo real time impulse/ETC analyzer.

This is quite fast, depending on settings and will allow a detailed look at early reflections with the highest possible resolution.

The best use I think is to filter it between about 1000 Hz & 10,000 Hz. I accidentally didn't have these as presets. The preset is 400 Hz- 4000 Hz.

Filtering is optional, but the filtered ETC is the best way to look at this- although it may not appear that way to some users.

Reducing or elliminating early reflections is absolutely critical.- particularly the really early ones, around 1 ms.

Hi Doug,

> I have just added a pseudo real time impulse/ETC analyzer. <

Very cool.

> Reducing or elliminating early reflections is absolutely critical. <

No kidding. There's a bit of a buzz going around lately about a new article in the AES journal by Floyd Toole where he says that some early reflections are useful. This has not been my experience though.

I'll download the latest version and give 'er a spin.

Now, the only thing missing from R+D is being able to set the dB and time ranges for waterfall plots. If you add that I'll be a happy man.

--Ethan

I was wondering if someone could clarify the setup for doing RplusD measurements. The setup that is indicated in the manual provides the input to the left and right channels of the amplifier through the 'Y' adapater. On my amp, I have set that input to be treated as stereo with no other signal processing. Therefore, the signal that I am measuring is a combination of the sub, the left and the right. Does it make sense to measure each individual speakers in a 5.1 system or does the default setup adequately represent the system? Thank you for any reply.

I think Dave Moulton was(or still is) a proponent of early reflections in playback systems provided they were of fairly even freq response. His website has changed since I was last over there, so I couldn't find the exact article.

Thanks for the kind remarks regarding my sig.

/jim

Hi BobE

You connect RPlusD using the left OR right input from the computer output. Either the left or right connection will get the correct signal going through left, center or sub.

If the right input is connected to the RPlusD output then the right, center or sub will get the correct signal.

Always make sure only one speaker is playing unless you are measuring multiple subs.

All subs should play through the sub channel but in other cases only one speaker should play.

If you are measuring center, make sure left or right is off and visa versa,

You can measure right or left with sub playing but make sure center is off.

You can only measure one MF/HF speaker at a time.

Doug,

Thank you for your response. I understood the output of the sound card but my confusion arose in regards to the input to the amplifier. Since the drawing indicates a 'Y' adapter, then both left and right are getting a signal. Is it better to:

1) not use the adapter and provide a signal to just the left or right or

2) use the adapter and disconnect the speaker not being tested?

Also, when using an omni directional microphone, do I point it directly at the speaker or straight ahead toward the monitor?

Thank you for your patience in answering these questions.

BobE

You can use the balance control to reduce the levels on the speaker or disconnect it.

As far as physical connectors go, they don't matter. Whatever is necesssary to make the connection should be used.

When using an mini mic it doesn't really matter where you point it unless you are trying to measure the HF response of your speaker accurately. In that case it should be pointed at the speaker.

OK. I can't get loop thru test to give me the correct results. I am using a Lynx AES 16 sound card and a Lynx Aurora converter. I loop the output of the Aurora to the input of same and run the test and the sn figure is always about 0 db? The other tests don't make much sense either but if the the loop thru is not right, I guess nothing is going to be accurate. I've tried various levels with the Aurora and the result is always the same. Do I have to use the CPU sound card(NVIDIA) or am I making some other mistake.

See if your sound card has a WDM driver. It may not have one with the app. In this case you will need to download a third party WDM driver. Yours appears to have this. Your soundcard should work.

It may be your left and right on input and output are mixed up. Ie left out connected to right in. This happens a lot sometimes "automatically" when the cables come (mistenkenly) wired that way.

Have you downloaded your latest driver from manufacter (Lynz)?