# First post. First readings. First impressions.



## modusmongo (Jun 26, 2013)

Hi folks. Thanks so much for this great software. This is the first time I have ever bothered to try to get really accurate sound.

I recently bought a pair of BC Acoustique Gange speakers - 3 way non ported four-foot-tall monsters. They are the best speakers I have ever owned. I'm powering them with a Peachtree Nova integrated DAC/tube preamp/stereo amp.

I run flac files from Foobar2000 - WASAPI event - s/pdif through a 14 meter 75ohm coax cable. I know that the Gange's are accused of having a weak spot in the midrange, and I can hear it. It was this lack that lead me to you ;-)

After messing around for a day, I finally got some readings. I am using an uncalibrated Audio-Technica AT4060 studio microphone for the readings - it's got a pretty flat response:









Here is my room: 7m x 5m x 3.5m ceiling ALL WOOD! Also a little speaker placement diaphragm thanks to hunecke.de.















I plugged the AT4060 mic into my presonus firestudio tube firewire (external 24/96 16 channel) sound card.

I calibrated the card with a loop as described in the software. I then took five readings of which I'd like to share three (mic placed where my head usually is). All 16/44.1:

1) BLUE - Analog out of the Presonus into the Peachtree.
2) RED - Digital from the TX1 s/pdif output on my computer's motherboard over my 14m cable.
3) GREEN - Using usb and the Peachtree as a soundcard.

First of all, the chart vertical is from 35 to 95db because I must not have used a loud enough signal. I'll do better next time. Smoothing 1/6 octave.









At first, I thought. Hmmm, the supposedly world class Peachtree DAC has gotten it's butt kicked by the Presonus Firestudio. I had never even thought of using the Firestudio as a DAC, but you can bet I did as soon as I compared these results. Indeed, the sound from the Firestudio, analog out to the Peachtree is superior given the conditions. "Given the conditions" is where I'd like to have better information so I can use whatever tools might be available to make the sound better.

Where should I start? I have some damping material on the walls left and right using the "mirror" method. A small carpet on the floor to avoid first reflection. Lots of junk in the room ;-)

How much of what we see in the chart is room? How much is speaker? How much is A/D converter?

Is there a link between these three readings that jumps out to you?

Are these charts unreliable for one reason or another?

Thank you very much for any help.


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## EarlK (Jan 1, 2010)

modusmongo said:


> <<<<<<SNIP>>>>>>>
> I calibrated the card with a loop as described in the software. I then took five readings of which I'd like to share three (mic placed where my head usually is). All 16/44.1:
> 
> 1) BLUE - Analog out of the Presonus into the Peachtree.
> ...


IMHO, the last 2 captures are pretty meaningless ( Red & Blue ) , unless you did additional loop-back measurements ( & then got the required flat line, indicating circuit linearity for each of your 3 setups ) .

ie; Who's to say, you didn't actually have a bunch of EQ engaged when you ran the Red/Purple & Green traces ?

:sn:


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## modusmongo (Jun 26, 2013)

Hi Earl. I did get a loopback flat for the blue because it was analog in and out of the Presonus. The other two are more difficult to test because the output to the sound system is s/pdif and the input to the sound card is analog. So I would need a way to convert the digi s/pdif to analog to get it to loopback to the sound card BUT then I would have to take the same A/D converter OUT of the signal path to make the test.

No EQ was applied in any of these tests. But My room is wood floor, wood walls and bare plaster ceiling. I think that I must have an enormous amount of decay...

Thanks for your response


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## EarlK (Jan 1, 2010)

If your plots are to be believed ( which I still don't ) , I would find the "red & green" traces to be un-listenable ( IME ) .

( Blue ?) I would want to reduce the 500-1000hz hump by at least 3db , as well as flattening that 170hz peak . 

:sn:


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## JohnM (Apr 11, 2006)

Probably worth posting the mdat file for the measurements for us to take a look at.


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## modusmongo (Jun 26, 2013)

Hi again Earl. Hello John. I can not upload the MDAT file because the upload page continually tells me "security token was missing." So I put it in a folder on my personal website: petermcc.com/mdat/ the file is called "june_30_13".

I guess I don't believe the two lower graphs either because when I try to make general parametric EQ corrections for those curves, the resulting music using the convolver files is terrible.

I can't think of a way to loopback test the onboard soundcard. I could do analog out to the presonus microphone analog in, but would that not add an extra A/D conversion which does not exist when I output sound directly from the motherboard s/pdif?

Maybe I should not bother you folks with my soundcard problems and instead, continue using the measurement in blue.

Yes, that is it. I made an eq file using the blue chart, exported it and loaded it into foobar2000's convolver. WOW! Now I can hear much more information. The sound is a bit too forward for me, so I hooked up my second amp to bi-amp the speakers with more bass. I do have an all wood room, so thinking "house curve", I turned down the volume and added more bass. Now it really sounds much better than before. When I A/B the previous sound is muddy. I put the EQ file ("4th try") in the same folder mentioned above if anyone would like to look at it.

Am I doing things backwards by using the separate amp to up the bass response? Maybe I should be doing that with eq...

I would love to take a new reading using the eq in-line, but I haven't found out how to do that yet.

Again, thanks for your help.


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## JohnM (Apr 11, 2006)

Use single sweeps rather than multiple sweeps, looks like synchronisation is not being maintained between sweeps so the time averaging does not work properly.


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## modusmongo (Jun 26, 2013)

I now have more confidence in the general wave form. Below is a comparison chart with:

1) GREEN - the analog in/out readings to and from the calibrated Presonus external sound card. You saw this the other day (unfortunately four passes).

2) BLUE - coax from the motherboard read by the same mic into the MB line in. I calibrated the motherboard sound card. This one is a single pass. I look forward to hearing what it means to you.

files here: petermcc.com/mdat in the 3 july zip file.

So the curve from two completely different setups is essentially the same. Do you agree that what we are looking at represents the speaker/room response? If so, where should I go from here? Thanks ;-)


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## EarlK (Jan 1, 2010)

> <<<<<SNIP>>>>>
> 
> 
> 
> ...


Yes those look like 2 believable captures .

(a) I would recommend you do some room treatment to bring your RT60 times down ( into the area of 3ms is good ) . The RT60 times ( for your listening room ) are too high for critical listening ( in my experience ) . 

*GIK Acoustics ( with an outlet in the UK )* can sell you pre made solutions for this task .

(b) If you want to EQ your system within your computer, then I would also recommend you learn how to use ( & implement ) REWs Auto-EQ module . 
- Create individual captures for each speaker ( without moving the mic ) from the listening position and then put each through the REW Auto-EQ process ( you can use the info you see in my last pic as a guide to get you started / I used your file to show you what is easily achievable ) . 
- Pink line is predicted response after EQ , while the blue line was the "target" response that I told REW to shoot for .

- Export the EQ filters as a text file ( or Wave file ) to be used either within a convolver hosted by Foobar or ( alternately ) hosted within  Equalizer APO  which is a system wide EQ that I think will work with either of your soundcards .

:sn:


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## modusmongo (Jun 26, 2013)

Earl you rock! Thanks so much for your time and expertise.

A pre-made room correction solution is not in my current budget, and is not really my style. I prefer to custom make things like this by hand. I had a look at the acoustics forum and particularly this thread. My intention is to get usable readings from REW and open a new thread over there to ask for help in creating a custom room treatment solution based on the mdat files.

Once the room is acceptably dampened (if that is the right word), I will buy/rent/borrow a calibrated mic/meter and create the necessary eq filters for the convolver in foobar. In the mean time, I have made a set of simple manual parametric filters which are sounding pretty good.
View attachment 6th try.req


I decided to try another mic this morning. I also wanted to put my mixing table in the calibration loop. So the calibration file in this file
View attachment independence day 2.mdat
is a loop from the analog sound card out to the ch1 input of the mixer, back out to the line in of the sound card. This still does not _*really *_calibrate the card because I use the s/pdif to output sound yet the test is done in analog, but what else can I do?

For some reason, the resulting chart is WAY higher, even though I set the in and out levels (as well as the amp volume) the same. Any idea what I did wrong here? Looks like the chart is about the same shape with a slight difference in the 10k bump. See below - today's reading in green.

Would you please look at the readings and let me know which I should use when I introduce myself over in the acoustics forum?

Thanks again. It's really great to have such willing help :clap:


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## EarlK (Jan 1, 2010)

modusmongo said:


> Earl you rock! Thanks so much for your time and expertise.
> 
> <<<<<<<SNIP>>>>>>>>
> 
> ...


You're welcome !

Since neither mic has an EQ correction ( calibration ) chart / you can use either ( since they are both equally suspect ) .

Be aware that the AT4060 ( with it's exaggerated 4db of ) presence/sibilance boost , skews the true HF of that capture ( ie; if one believes the literature , your capture shows more HF than is actually present ) . 
- This means that when you eventually EQ your speakers ( if still using that mic ) , you'll need to EQ the HF to "taste" ( & not go by any pic, such as the prediction trace that I posted previously ) . 

I don't know why this new capture would be higher by 56db ( excepting if you somehow deleted REWs preferences and then ran the software without the SPL meter being calibrated ) .

You can add a ( - 56db ) offset to the new capture to make it over-lay better with the first. 
- Look within the "Controls" window which is opened up by clicking on the "gear" looking icon ( seen when a file/trace is open within "SPL & Phase" ) ,& located over the far right scroll bar .



:sn:


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## modusmongo (Jun 26, 2013)

Hi again.

I will get a calibrated mic/meter for the final readings after the room is properly treated.

Two quick questions.

1) Am I ready to start treating my room based on the readings I have?

2) Is the correct etiquette to start a room treatment thread in the Acoustics forum, or to invite them over here by PM, or something else?

Thanks


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## EarlK (Jan 1, 2010)

modusmongo said:


> Hi again.
> 
> I will get a calibrated mic/meter for the final readings after the room is properly treated.
> 
> ...


(1) Yes, your readings are fine for the purposes of pursuing some advice on employing room treatments .

(2) Definitely have that conversation over within the Acoustics Forum ( hosted by Brian ).

(3) I believe it's a very good idea to gather up some info first ( via passive observation ) , so that you gain perspective & get your expectations in line with the reality of DIY Room Treatments .

- A good place to start is to read & ponder the meaning of this ( sticky ) thread ;  *Foam vs GIK 244 Panels .* 

- You might also want to observe the meanderings of the many threads ( on the subject of room treatment ) over at  *Studio-Building-Acoustics .* 

- Specifically, you could monitor  *this thread ( somewhat choosen at random )*  to see if the OP ever gets some advice that "enough is enough" and to "EQ the rest" ( highly doubtful given the players ) . 










- My point ( & personal take-away from that sticky & all the other forums ) is that when employing treatments ( below @ 300 hz ) only decay times get altered ( excluding physically shifting speakers around ) & that it's a very rare case where one can fill in deep nulls in the bass response ( via trapping enough LF energy ) with simplistic products like wall panels, "clouds" & corner located ( broadband ) superchunks . 
- "Tuned", narrow band absorbers ( specialty products ) are needed / & the "how-to" info ( for their DIY manufacture ) is not generally available to the public .
- One needs to do their own "Cost vs Benefit" study before going too far "down the rabbit hole" of room treatment .

- Personally ? I believe in employing a reasonable balance between "drc/EQ" & "room-treatment" ( & sometimes just not "sweating the small stuff" ) . 

:sn:

PS : Here's a treatise composed by 2 acousticians offer some direction for how acoustics can support good 2-chnl listening ( & what to look for in measurements that would enhance or detract from that experience ) .


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## modusmongo (Jun 26, 2013)

Okay, thanks Earl.

I'm not worried about the bass, I'll be happy to eq and let it be. It's the muddy midrange that is bugging me. I can't listen to rock at any decent volume because the reverberation of the room in the midrange and treble get in the way of the original signal. I'm hoping to improve that by bringing the T20/T30 down as low as I can get without breaking the bank.

I'll come back and let you know how it goes


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## ifix4u (Jan 28, 2016)

How exactly did you calibrate your Firestudio. That's where I seem to be having problems.. How did you set it up in the preferences (exactly), which input did you use, and which output did you use. When I did mine I got a crazy wavy line, I think its supposed to be a fairly straight line. Any help would be greatly appreciated. Thanks in advance......


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## modusmongo (Jun 26, 2013)

ifix4u said:


> How exactly did you calibrate your Firestudio. That's where I seem to be having problems.. How did you set it up in the preferences (exactly), which input did you use, and which output did you use. When I did mine I got a crazy wavy line, I think its supposed to be a fairly straight line. Any help would be greatly appreciated. Thanks in advance......


Hi ifix4u,

You need to apply smoothing to your graphs. In REW, go to the Graph menu (top left of your screen) and select "Apply 1/6 smoothing". You need to experiment to see which level of smoothing is best for you, but you'll see right away that it wll make sense of your presently unreadable chart.

As for the Presonus Firestudio, I didn't make any changes. I entered flat at 24/48. Only adjusted the volume until it was good.

To get really good and dependable results, you'll need to get a usb microphone like the minidsp UMIK-1 (something with a calibration file).

Good luck!


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