Doug,

I just went up to 1.2.9 from 1.2.4 and noticed that the waterfall plots look like they got truncated (the decibel range is smaller). Is there a new setting that I'm not seeing?

Thank you.

Bob

BTW: The new manual is looking good and I'm learning quite a lot from it. Looking forward to seeing it completed.


06/17/07 Re-installed the software and everything seems to be working correctly.

bob

Doug,

did you receive the emails I sent to you in the last week or so ?

I just got some strange messge saying your mail was not deliverable........

Rod

Thank you Dough for your answer regarding the 25 Hz peak.
Some questions regarding R+D and acoustic:

1-If some speaker produce a rattle sound (for any cause, i.e.: lose driver...) when it is fed by lets say a 30 Hz signal and this rattle has a frequency maybe around 400 Hz, How is it going to be reflected in the R+D frequency response curve ? Is there going to be some peak at 30 Hz or at 400 Hz ?

2-How noise affect the frequency response curve. Lets say the S/N RATIO curve is very flat at 25 dbs but has a dip between 300 and 400 Hz. Is it predictable to say that the frequency response curve is going to have a dip or a peak around this frequency ?

3-Ethan, I have been reading your articles regarding room acoustic. I understood that there is not such a thing as "too much low frequency absortion", but where would it be more effective to place some of this rigid fiber glass panels, corners close to subwoofer-speakers or corners in the opposite side of the room (listener side) ?

Thank you,

JC,



The noise should show at 400 Hz. However, I believe R+D uses a tracking filter specifically for this reason. Hopefully Doug can clarify this. The basic idea is the software filters out everything except the current frequency of interest as it sweeps, which increases the signal to noise ratio of the measurement. For example, if a dog barks in the next room while the sweep frequency is 50 Hz, only 50 Hz is measured and the dog bark is effectively eliminated.



I'll let Doug handle that one.



The idea that you can't have too much bass trapping is my own, based on my own experience. Some people disagree with that, and some even argue that bass trapping is never necessary. Obviously, they're wrong. But it's always useful to know all opinions.

Anyway, to answer your question, the best place for bass traps is where the bass accumulates in the room. This is much more important than having it near to a sub, or near to the listener, etc.

--Ethan

"How noise affect the frequency response curve."

I've just finished five chapters of a new manual and posted it. Each chapter is 20 pages or so with measurement examples.

This question is addressed on page 16 of chapter 1.

There are diagrams and a good explanation of the noise issue.

This manual is much easier to read than the other support literature I have written because it was written unhurredly.

People have said that they had no idea how good the software was until they read the manual and saw what it can do. This is the current problem I experience - people just think its another ETF but it really is so much better than ETF in every possible way.

Its very easy to use once you have read the manual.

"Ethan:The noise should show at 400 Hz. However, I believe R+D uses a tracking filter specifically for this reason. Hopefully Doug can clarify this. The basic idea is the software filters out everything except the current frequency of interest as it sweeps, which increases the signal to noise ratio of the measurement. For example, if a dog barks in the next room while the sweep frequency is 50 Hz, only 50 Hz is measured and the dog bark is effectively eliminated."

That is essentially it but there should also be a big peak at the rattle frequency since the speaker is producing the rattle.

"Rod Gervais:did you receive the emails I sent to you in the last week or so ?

I just got some strange messge saying your mail was not deliverable........"

My email server was being rebuilt and they were bouncing emails. Should be fine now.

I've recommended your book in Ch4 of my new manual. (Practical Measurements)

Try sending me an email now.

Sorry for the hassle.

"Bob E:I just went up to 1.2.9 from 1.2.4 and noticed that the waterfall plots look like they got truncated (the decibel range is smaller). Is there a new setting that I'm not seeing?"

I did change that a bit, the trick is to grab the response containing about 5 - 10 peaks. It now does a better job of finding the noise floor - there was bug in the older calculations for noise floor

Doug,

I tried another email - and got a message back saying that it was delayed - not refused - ut delayed - let's see if it makes it through....

Rod

Hi,

I have a general question:
When you produce a waterfall from measuring a sine sweep, how can you make sure the decay of all frequencies is accurate, since each particular frequency range is excited only for a short period? Wouldnt exciting a (modal) frequency for a longer time also lead to longer ringing times?

Thanks

Maybe Doug will elaborate, but the software knows what it's sending and can compare that to what's picked up by the microphone. Whether the signal is long or short doesn't matter, as long as the software knows what it is. More to the point, the signal can sustain for three hours if you want it to. The decay time is considered to start whenever the source signal stops.

--Ethan

Doug,

still no uck on sending you an email - this is the message I just got from the send of the other day.......



Sorry buddy - but I can't get through...........

Rod

"When you produce a waterfall from measuring a sine sweep, how can you make sure the decay of all frequencies is accurate, since each particular frequency range is excited only for a short period? Wouldnt exciting a (modal) frequency for a longer time also lead to longer ringing times?"

That would require a textbook to explain but it can be done perfectly with no error.

Doug, Ethan, guys:
I'd like to use the R+D's EQ RTA TUNNING tool.
What I have is a digital equalizer (Z-System rdp-1) with just digital outputs and inputs, I have a D/A converter so I guess I will be needing a A/D converter to connect the analog sound card output to the equalizer.

Does anyone knows any affordable one ? below $300 ?

Other option ? :
I bought the USB-Mic Pre-amp from Doug, but...
If I use a different USB Sound Card for my Laptop with digital and analog outputs, Can I keep the analog left channel loop and use the Sound card digital out to be connected to my equalizer digital input then the equalizer digital out to my D/A converter and finnaly finish the right channel loop conecting the right analog output from the converter to the sound card right analog input ? Is that clear ???

Another question:

Almost in every measurement I have made in my listenning room I always get a -10 dbs depressed area between 250 and 350 Hz in the frequency response curve. The only time I didn't get this result was using the "Speaker Direct Sound Measurement" procedure described in the R+D new Manual. In this measurement the speaker were just in the middle of the room and the mic-speaker distance was about 7'. My room is 23'x17'x9'.

What could be happening ? Too much absortion from a sofa or anything in the room ?
My speakers are Audio Physic Avantis, these have two woofer drivers one by each side and the mid and tweeter drivers are about 2' higher in the front of the cabinet.
Could this depressed area be a crossover point ?



Thank you,

Jesus

Doug,

How much difference should one expect between the two ETC methods in RplusD? (The third being the real time one) My results between the two are quite different and I'm not sure if I'm missing something or if you're using different methods of calculations for each method.

Thank you.

Sorry to have bothered you. After redoing everything on my desktop everything appears to be better. I'm not sure why I was originally getting different results on my laptop.

Bob

Bob E: Sorry for not getting to this sooner.

"I bought the USB-Mic Pre-amp from Doug, but...
If I use a different USB Sound Card for my Laptop with digital and analog outputs, Can I keep the analog left channel loop and use the Sound card digital out to be connected to my equalizer digital input then the equalizer digital out to my D/A converter and finnaly finish the right channel loop conecting the right analog output from the converter to the sound card right analog input ? Is that clear ???
"

Draw a diagram bitmap and send it to me by email or just try it.

"Almost in every measurement I have made in my listenning room I always get a -10 dbs depressed area between 250 and 350 Hz in the frequency response curve. The only time I didn't get this result was using the "Speaker Direct Sound Measurement" procedure described in the R+D new Manual. In this measurement the speaker were just in the middle of the room and the mic-speaker distance was about 7'. My room is 23'x17'x9'.

What could be happening ? Too much absortion from a sofa or anything in the room ?
My speakers are Audio Physic Avantis, these have two woofer drivers one by each side and the mid and tweeter drivers are about 2' higher in the front of the cabinet.
Could this depressed area be a crossover point ?
"

I'm not sure what could be causing this but it could be a problem with your sub - main crossover. This is very strange. Take a few measurements and average them.

Send me the measurement by email - compress the file to about 600 ms "Tools->Compress" from main menue.

Doug, I also am getting email bounces from your etfacoustic.com domain mail server.

The address to which the message has not yet been delivered is:

admin@etfacoustic.com
Delay reason: Connection timed out:
SMTP timeout while connected to mail.etfacoustic.com [209.205.25.141]

You might want to look into to that, or please PM me with an alternate email to use.

I've been trying for weeks to send something.

Hi all,

I worked with Doug to get some Vista issues squared away as far as installation on Vista Business. It seems now I have a feedback issue and I'm looking for thoughts on this. My setup is:
Behringer Microphone --> Behringer Mixing board --> Tape out to sound blaster MP3+ (external usb sound card).
The left channel is looped through output-->input, the right channel line out is connected to my pre-amp with a Y cable so it goes to both L/R in.

My impulse response showed something like 5db S/N whereas the soundcard test had showed 35db signal to noise. I tried turning up the Mic level on the mixer, the main out on the mixer. This results in a feedback loop that causes me to quickly turn the volume down before I break something. Are there common causes to this situation I can look into?

JonFo, I can also be reached at dplumb1417@rogers.com

I will be publishing a PDF file describing how to find and load a few files into Vista to get RPlusD working.

Vista doesn't ship with a few necessary files for RPlusD. These can be added manually.

The dplumb address will not work. Sorry about that

I am having some problems with my etfacoustic.com address. Try again or call me. The server is often down.

Hello to All,
I am new to the forum and wish you all the best.
I have been able to get my initial succesful measurements with the software and I have a question on the interpretation of results. It concerns the difference between the psycoacoustic and the 1/3 oct responses. In my case, there is a marked difference between the two, in the area below 100Hz, i.e. the psycoacoustic one, showing much reduced energy (>10db) in the area of bass frequencies, versus the 1/3 oct. Reading the appropriate chapter I know Doug says that the curves may be very different. The question is, which one to you try to optimise by, say, changing positions etc. In my case if I believe the 1/3 oct, then I have really virtually no problem in the low region - but if I follow the psychoacoustic one, then... I have virtually no bass (exageration of course). Any opinions / advice will be appreciated.

Doug and Ethan:
I've been using the RplusD software for a while now, with the Calibrated Mic and Pre-amp sold by ETF. I kind of understand the measurements procedures described by the manuals, using only one speaker, and that those procedures are intended to meusure among other things Room Resonances, Direct (no room) Speaker Response and Speaker Power Response. I believe this measurements evaluate the Room and the Speaker but It does not evaluate the room-system interaction. I have read that measurements using both speakers are not recommended. My question:

Why measuremets using both speakers and in my case a sub-woofer at its normal position should not be used ?

Wouldn't be this a way to determine the real system response at least for one single spot for the listener ?

Wouldn't this measurement show the result of bass cancelation given the 3 sources working together as the listener would perceive it ?

Thank you,
Jesus

ST13: "Hello to All,
I am new to the forum and wish you all the best.
I have been able to get my initial succesful measurements with the software and I have a question on the interpretation of results. It concerns the difference between the psycoacoustic and the 1/3 oct responses. In my case, there is a marked difference between the two, in the area below 100Hz, i.e. the psycoacoustic one, showing much reduced energy (>10db) in the area of bass frequencies, versus the 1/3 oct. Reading the appropriate chapter I know Doug says that the curves may be very different. The question is, which one to you try to optimise by, say, changing positions etc. In my case if I believe the 1/3 oct, then I have really virtually no problem in the low region - but if I follow the psychoacoustic one, then... I have virtually no bass (exageration of course). Any opinions / advice will be appreciated. "

Send me your file by email. Zip it up first.

You should find the sub placement that excites the most room modes. I've added an example in the manual about this. Then you EQ or add room treatment to control overexcited resonances using the psychoacoustic as a guide for overall perceived levels. Sometimes you need a sharp resonance to keep levels up and you leave that alone.

"J Corner: Why measuremets using both speakers and in my case a sub-woofer at its normal position should not be used ?

Wouldn't be this a way to determine the real system response at least for one single spot for the listener ?

Wouldn't this measurement show the result of bass cancelation given the 3 sources working together as the listener would perceive it ?"

You cannot determine a single defining frequency response of the equipment operating in a room. You can use frequency response to find audible problems.

All your bass speakers should be operating when doing LF tests below about 100 Hz - 200 Hz, above 500 Hz your speakers are operating in stereo and should be considered independent.

Its impossible to establish a frequency response between about (100 - 200) Hz and 500 Hz but what you can do is look for very sharp resonances that may need EQing. In my room I had to set 3 filters to control a set of resonances around 140 Hz that looked like only one resonance- it was room modes piling up in one spot - this is ideally corrected by EQ.

Greetings gentlemen. My new facility's been under construction for some time and I've been anticipating using my ETF 5.x software for a while now. Just realized that the preamp has gone missing. Doug emailed me that there's a USB preamp card available for the test mic as well as the RplusD upgrade for ETF users. Looking forward to diving in head first (my first time with an analyzer vs. tones and an SPL meter). I'll try to catch up and read this thread from the beginning. When the new sound card arrives I'll probably have lots of questions for all of you. I'm already familiar with Ethan's reliable and thorough assistance from the gearslutz & TapeOp forums. Looking forward to picking all of your brains collectively and hopefully contributing when get things sorted out a bit.
Thanks in advance!

Hi
Just joined,
and also just bought RPlusD, within the hour,
though it is not on a running computer yet.

Anyone every use an Earthwroks QTC-1 mic with this?
It is one of my recording mics, but and exceptionaly flat one,
often used as a reference mic. I have a matched pair,
that I would never part with.

I am in the 'almost testing' stage of a
Non-Environmental control room
9.2m long x 7.6m wide 5-6.m Tall.

So I needed something besides Spectral Foo for this.
But nothing on a Mac seems high powered enough.
No waterfall or low freq room mode displays etc.

So I will haul out a rarely used PC and run it up the flag pole.

No doubt I will have some questions here,
but I have used the old Crown Techron in the past
and have some clue about this stuff.

But of course ANY control room is a brave new world
till you know what it REALLY does.

DD

Yes, that type of microphone is fabulous for room analysis. I use a DPA 4090 which is similar - omni condenser with a "tiny" diaphragm.


For Macs, FuzzMeasure is your best bet:

http://www.supermegaultragroovy.com/products/FuzzMeasure/

--Ethan

Hello Ethan. I guess, considering the previous posts, this refers to you...again. I got a Presonus Firebox for my RplusD measurements. I realised that I need an incredible amount of gain (software+harware around +55dB for 75dBC SPL at mic) to achieve respectable results in S/N and Mic Input Level. I was wondering...Is that normal? The mic I'm using is an ECM-40 Stage Line with sensitivity around 5.5mv/pa.

Thanks,

Harry

I don't know that microphone, but I use a FireBOX and never had a problem. Are you playing the test signals loudly? They need to be pretty loud to overcome the ambient noise in the room by at least 40 dB if not more.

--Ethan

I think it's the sensitivity factor. I found out that your DPA mic has around 20mv/Pa!! where mine a poor <5.5mv/Pa. Do you remember if you have to make use of the +15dB sofware gain in mic input? The truth is that my test was made at 75dBC SPL at mic capsule. Again, this does not cover the 40dB range you mentioned above but with the use of RplusD sweep tone should be enough for a room measurement. If you are interested in checking the Stage Line Mic here's a site that sells ETF as well...

http://www.content.ibf-acoustic.com/catalog/product_info.php?cPath=21_23&products_id=34


Thanks,

Harry

Can you increase that to 85 dB? That's gotta help!

--Ethan