As far as mics go, its important to use an omni mic to standardize measurements. You can't have a standard directional mic.

The RS SPL meter is fine for the room applications. Anything better than the RS meter is only needed for Eqing. It will become directional above around 5 KHz but in room reflections (band filtered ETC)the frequency response of the mic itself is irrelevant. The directional characteristics of the mic are all that matters and these are omni directional below 5 KHz. The ETC can be set to only show affects of content below 5 KHz.

These mics are close to ideal in the low frequencies down to about 30 Hz. The ritical band of 100 Hz - 5 KHz is well handled by these low cost mics.

I sometimes still use my RS meter. It depends on which has the battery in it usually. When doing EQing a calibrated mic is necessary.

David,

> where would we ever get to hear one of your recordings? <

You can download most of my projects from my Tunes page:

http://www.ethanwiner.com/e-tunes.html

Thanks for asking.

--Ethan

Ethan,
Thanks for the "Ring is right" tip.
It was my (relatively) expensive Audioquest y adapter (looks more like an "F" actually) that had the L/R switched.
Booo...

-Mike

"You can download most of my projects from my Tunes page:
"

Ethan, that was AMAZING !! I love the cello. (and the piano) but the cello more.

I need to burn that so I can play it on the big system.

Thanks!

Doug,

I just updated to the latest version of RplusD and now when I select new soundcard measurement, I get a 'Run Time Error 5'. Any thoughts or should I just go back to an older version which had been running fine?

Thank you.

Bob

Does anyone know if R+D will run properly on Vista?

I have a Vista Laptop so unfortunately, I have no choice. Any special or unique settings I should know about for running on Vista? assuming it works of course Thanks, Bill

"I just updated to the latest version of RplusD and now when I select new soundcard measurement, I get a 'Run Time Error 5'. Any thoughts or should I just go back to an older version which had been running fine?
"

Go to File->Clear->Delete Auto Mixer Settings. Set your mixer and go ahead.

I did the final bit of touchups on the auto mixer code and that is causing this.

"Does anyone know if R+D will run properly on Vista?
"

Its fine on Vista

The above problem was with an older version. No one downloading the version posted will experience this problem.

Doug,

Thank you.

Bob

Proper setting for the RadioShack meter for use w/ RPlusD is "C" wtd, correct? (with cal file) Does the response speed alter the mic output?

I've had the software for a while but haven't used it much. I did watch the videos and it seems like most of the options are more for post-acquisition processing rather than needing to be set up perfectly pre-acquisition. Is this the right way to see it? I am soon going to do a bunch of measurements and want to get the acquisition part right and worry about the fun stuff later. What are the critical parameters that need to be set before acquiring data sets that can be crunched later, if this question is possible to answer!

Thanks!

Hi Doug,
I have the sound card setup according to instructions. It is working fine.

Now how do I run a test? Procedure is not described in your 'Ch1' video.
Thanks
Rich

mfsoa:

The weight setting doesn't matter. If you do not get an immediate response from me on the group then just send me a quick email.

Most of the options shown in the video are post data gathering. You do not even need to have a cal file loaded when you take the measurements - you can add it later.

Data taking is very easy.

You set up the sound card using the loop through test with the level check. Once this is seen to be OK then you change your wiring so that your right output on the sound card goes to the audio system and the left input connects to the mic. Use the middle button "Start Test" on the same window to take an actual measurement.

Note the mic/speaker distance option on the bottom part of the window. If you are just measureing a subwoofer alone then set this to manual and input the mic / speaker distance. This only has to be accurate to a meter or so.

This should help you too richidoo.

OK. I have been able to do a test. The File | SOund Card Measurement command was confusing me, I thought that was just for setup. I can see this will be a steep learning curve.
Thanks
Rich

I have just added a consultation to the purchase options. It is described in the credit card purchase system. I know a lot of people have more money than time and I can walk you through all this + interpret measurements and give advice.

I think this is a great idea, and also fair.

Now, if I could just figure out how to charge people for asking me endless beginner questions for half an hour on my toll-free sales line, and then not buying anything.

--Ethan

Doug hi there...I've got some questions for you cause I'm getting a bit confused...:

1)Why there's always a small negative peak in the impulse response window before the main impulse? Is it part of the first wavefront? Which part is considered to be t=0 for my measurements? The high level positive peak or the low level negative? Bare in mind that the speaker is not connected out of phase (so first peak has to be always positive).

2) What is usually the reason of non-decaying levels at different frequencies in the waterfall plot (much above room modes)? Can it be cable hum? Cabinet resonance...?

3) Is there a way not to load each time I'm making a new measurement the cal file for my mic? Can I set it up as a default file?

Thanks for reading,

Harry

I'm not sure if I have to pay consulation time for these answers...Does anybody know?

Thanks,

Harry

No, there's no fee for anyone's help here! This thread isn't as active as others, so maybe Doug Plumb doesn't check in every day. Send him an email and tell you asked him some questions here. I'm sure he'll be glad to answer you here.

--Ethan

Ty Ethan...I tried once, a week ago. I'll try once more.

H.

Harry,

The problem is likely that your card does not have Windows WDM drivers. Type your card make and model with 'WDM driver' in Google and you will be able to find a free 3rd party driver.

"1)Why there's always a small negative peak in the impulse response window before the main impulse? Is it part of the first wavefront? Which part is considered to be t=0 for my measurements? The high level positive peak or the low level negative? Bare in mind that the speaker is not connected out of phase (so first peak has to be always positive)."

This is a bit of pre ringing in your sound card and it shows because your left and right channels are not identical.

The impulse response is only useful for verifying that the system got the measurement correctly. You cannot draw any conclusions from the impulse response - that is why we have ETC curves. If you are concluding something based on the impulse response then you are doing something wrong. Always use ETC's and frequency response. The impulse cannot be used to "read" anything.

"2) What is usually the reason of non-decaying levels at different frequencies in the waterfall plot (much above room modes)? Can it be cable hum? Cabinet resonance...?"

Thats usually it - some kind of steady state machine noise.

"3) Is there a way not to load each time I'm making a new measurement the cal file for my mic? Can I set it up as a default file?"

You have to re load your mic cal file each time you generate a curve set of measurements. RPlusD is built so that if you forget you can add the calibration file to the file after you take the measurements if you forget. Presets make the program confusing sometimes.

Thanks Doug I'll check for those drivers...But what if I want to convolve the impulse response with some audio files will it give the expected result? I know that impulse itself is not of a much use but on the othe hand it gives at least some information about drivers' polarity...

Harry

Hi,

I just started using R+D (version 1.2.8) and have run into snag; I get this error message a lot when I try to make a series of measurements:
"User Error: The same calibration file must be used for all measurements. Reload initial *.cal file"
When I reload the calibration file, sometimes I get a good measurement and sometimes I get the message again. Sometimes I have to reload the cal file several times before I can get a measurement. Am I doing something wrong or is this a bug in the program?

Thanks,
John

Johh, as you might have noticed I posted a similar question to Doug some days ago. What I do in this case is to reload the calibration file (by cliking load --> *.cal file --> open)EACH time before I make a new measurement. The other thing you can do is to load the cal file after you've done with your measuremnts. Up to now I think that the latter is the easiest solution.

Harry

Thanks Harry. I'll try the approach since the first doesn't work reliably for me.

Thank you Ethan and Doug for this forum.

I just bought the software and the Cal. Mic with the USB-Mic pre-amp and I have been reading all the support files and getting to know the software. Just one question:

For meassuring low frequencies, which type of test signal give more resolution or best S/N ratio? According to the software's Help file I believe it is the SWEEPS signal but I belive It doesn't say exactly so.

With a 22'x17'x9' room and floorstanding speakers which goes down may be to 40 or 35 Hz, I always get a big broad peak at 25 Hz. This peak is a triangle with around 10 db in height and a base from 20 to 35 Hz. The curve seems acceptable flat from 20 Khz down to 35 Hz. Moving the mic around change the curve, but the peak is always there, bigger or smaller. The same happens if I use the RadioShack SLM instead the calibrated mic. I tried a very small speaker with just a 3 inches driver and the curve starts to drop very fast from 60 Hz to around 35 Hz (- 40 db) and then again the peak appears down there. Meassuring just the subwoofer I got the peak again.
I think my meassurements are not reflecting a real response or at least not with the enough resolution below 35 Hz.
In order to set a subwoofer with floorstanding-good-low-extension main speakers I think it is important.
Am I doing something wrong ? Is this the first mode for the room's lenght ? My comments refers to the Bode response curve.

Thank you.

Top

As I understand it, in the older ETF software the sweep signal is better because it yields a better signal to noise ratio. But with R+D, even if you use the noise signal it still plays tones at low frequencies. You can hear those moving around under the noise. But I always use the sweep tones option anyway. Maybe Doug will chime in and elaborate.



Interesting. Is there a chance it's a furnace or air conditioning unit rumbling? Or truck traffic from a nearby freeway? Or your footsteps on a shaky floor?

--Ethan

NOTE: I deleted your other identical post in the main forum.

RPlusD has sweeps as well. They are just as good as the ones in ETF.

The big peak at 25 Hz sound like noise.

Thank you Doug and Ethan.

I am going to check for noise but a have a dedicated listenning room with good isolation from posible outside noise sources.
I am running a long (35 feet) interconnect cable from the Mic pre-amp to the system input, Could this noise be RF pick it up by the cable ? or any other electronically generated noise ? I'll check...

Thank you again

Jesus

Its likely low frequency noise from a big machine like a dump truck or washing machine.

You could compress and email me a single curve shot and I will look at it. Use tools>compress and about 600 ms of truncation on the file before you send it to me. Just one curve will do.