[Guy 13]

Hi all Audio Circle members.
I know some Audio Circle members will not agree with the procedure or with the test equipment I have used for my test,
but it’s a little test I wanted to do to give me a rough idea
of the acoustic of my listening room.
This test might be useless to some, but for me it’s useful, as it give me an idea of where the offender frequencies are.
If you want to comments (Good or bad),
please do it gently and politely.
I am open to any comments as long as they are constructive
and polite.
I write this, because in the past some Audio Circle members,
blasted me for what I did that was not according to the book.
My SPL meter is:
Sinometer # JTS-1357
set on “A” weighted and slow response and 30 to 80db scale.
Ambient noise in my listening room is: 40db. (Late at night)
My sinewaves signal generator is:
Tenma # 72-505
20 to 10,000 KHz (It goes higher,
but my SPL meter is limited at 8,000 KHz.
Here is the chart I made from my test.
The problem areas are at 75Hz, 100Hz and 420Hz
The 2,800 Hz is not the room, but the Audio Nirvana 8” full range driver itself.
There it is; any (Constructive) comments are welcome?

Guy 13










 

[Ericus Rex]

Hi Guy,

I did a similar test when I had to prove to a vendor that the tweeters in my speakers weren't working properly.  I used the SPL meter like you but I used the Stereophile test CD that contains frequency tracks from 10 to 20K Hz.  I'm not sure how your results will tell you what exactly to do with your room treatments to tame those hot spots of yours.  What are you thinking?

[Ethan Winer]

This test might be useless to some, but for me it’s useful, as it give me an idea of where the offender frequencies are.

Your test is certainly not useless, but it hides a lot of detail because it only spot checks the response at third-octave frequencies. Most rooms have many narrow peaks and nulls throughout the bass range. The first graph below was measured using the free Room EQ Wizard software, and you can see many deviations in between the standard third-octave frequencies. Another limitation of your measurement is it shows only the raw response, but not "modal ringing" which is just as damaging to bass fullness and clarity. The second graph shows the same data as the first graph, where the "mountains" come forward over time. More here if you're interested:

Room Measuring Primer

--Ethan

[Guy 13]

Hi Guy,

I did a similar test when I had to prove to a vendor that the tweeters in my speakers weren't working properly.  I used the SPL meter like you but I used the Stereophile test CD that contains frequency tracks from 10 to 20K Hz.  I'm not sure how your results will tell you what exactly to do with your room treatments to tame those hot spots of yours.  What are you thinking?

Hi Ericus Rex and all Audio Circle members.
I also have a CD from Stereophile and Chesky with frequencies tracks,
be I prefer my portable frequency generator,
more convenient, for me anyway.
My Rega Apollo CD playerè remore control is a pain in the neck
when it comes to jump from one track to another
or to repeat a track.
Right now, I am seeking some opinions from other Audio Circle members
more knowledgable than me,
then I will see what direction I will take with my microscopic budget.

Guy 13

[Letitroll98]

Ethan is of course absolutely correct about the measurements.  However how they're going to be implemented is just as important.  When the usual answer is use some bass traps, and that's the limit of what is going to be done, it's only academic to go more refined than 1/3 octave.  If you're building a dedicated listening room then you need more precision.  So, what are your ultimate goals guy13?

[Guy 13]

Hi Mr. Winer and all Audio Circle members.
Thanks for your post and the link, very, very informative.
Tonight, I will go to bed smarter
or at least with more knowledge in my head.
Thanks.
Even if I go with your way of mesuring
(Laptop, I have and microphone I don't),
I still have to find some money for my room treatment,
which will take quite some time.
Sorry, if I have to repeat that I am on a microscopic budget
and any form of room treatment is (For) expensive
because cannot be purchase locally (Vietnam)
and has to be imported, even the raw material,
after paying the transport and the custom tax,
my cost oversea is multiply by two.
Anyway, I wanted to have a (Small) idea
of the acoustic of my listening room
and I got it, even if it's only partial.
Thanks again, I am gathering information
or increasing my knowledge on room acoustic
and I do realize that good sounding room accounts for 50% of the result.
I did read everything in the link you mentioned, that's lots of reading, but it contain good information.

Guy 13
Every day learning something, makes your life more enjoyable.

[Guy 13]

Ethan is of course absolutely correct about the measurements.  However how they're going to be implemented is just as important.  When the usual answer is use some bass traps, and that's the limit of what is going to be done, it's only academic to go more refined than 1/3 octave.  If you're building a dedicated listening room then you need more precision.  So, what are your ultimate goals guy13?

Hi Letitroll98 and all Audio Circle members.
My ultimate goal ? ? ?
To tell you about my ultimate goal,
I have to see in the future,
which I cannot , at least right now.
So that you understand better my position,
I have to share with you my (life) BIG problem.
I am not and I will never be shy of sharing some things about my life
with other people, so they understand more clearly the (My) situation.
First my revenues from my Canadian government pension
(Retirement fund) as been cut by 75% due to unpaid due
to my ex-wife in Canada.
(Total amount to be paid is 350,000 Cnd $
Second, I am not sure when I will be going back to Canada
due to my (Now) extremely small revenu, income.
Therefore, if I invest money on acoustic treatment on my listening room
and I go back to Canada, that investment will be lost.
Sorry to annoy you with all that,
but now you have a better picture of my (Financial) situation.
Therefore, for now, I will not do much,
unless I win the Vietnamese jack pot which is only about
maximum 100,000 USD.
And, If I do win at the lottery,
I will invest that money on my return to my home country Canada.
That's it for now.
Any comments, suggestions are all welcome
or if you want to share your win at the lottery,
that's O.K. with me.

Guy 13
 

[JLM]

OK, first please clarify.  You state that background noise is 40 dB, so should your chart be read as 40 dB higher than the stated readings?  (That would place them up to 130 dB, which should be painfully loud.)  If not, how do you have readings below 40 dB?  And how is it that those 4 good sized woofers (not familiar with your speakers) are 30 dB down at 50 Hz?  Do you listen near field (where the mike is shown)?  Why not measure from where you listen?  Not sure if your speakers are dipole or bipole, or if near field testing makes sense/works with either design.

My first attempt used a Radio Shack analog meter with Stereophile CD test tones, but got better results using a Behringer DEQ 2496 with ECM microphone (both from my near field listening position).  Do you know how accurate your signal generator and/or meter are?  (Radio Shack meters have well documented inaccuracies, especially at lower frequencies.)  I also recommend doing each channel separately (my matched drivers varied in my nearly symmetrical room by up to 6.5 dB).

As I've stated before, the room acoustics priorities should be: speakers (duh); proper room (bigger is better with good length/width/height ratios to avoid reinforcing echo); treatments (but don't over do as we're conditioned to listen to 'typically furnished' rooms); EQ (only as a finishing touch). 

Read Floyd E. Toole's 'Sound Reproduction'.  It recommends a variety of good room ratios, touches on treatments, and pushes the need for having multiple subs.  Without multiple subs no room will produce flat bass response, except in particular locations at particular frequencies.

[Letitroll98]

Hi Letitroll98 and all Audio Circle members.
My ultimate goal ? ? ?
To tell you about my ultimate goal,
I have to see in the future,
which I cannot , at least right now.
So that you understand better my position,
I have to share with you my (life) BIG problem.
I am not and I will never be shy of sharing some things about my life
with other people, so they understand more clearly the (My) situation.
First my revenues from my Canadian government pension
(Retirement fund) as been cut by 75% due to unpaid due
to my ex-wife in Canada.
(Total amount to be paid is 350,000 Cnd $
Second, I am not sure when I will be going back to Canada
due to my (Now) extremely small revenu, income.
Therefore, if I invest money on acoustic treatment on my listening room
and I go back to Canada, that investment will be lost.
Sorry to annoy you with all that,
but now you have a better picture of my (Financial) situation.
Therefore, for now, I will not do much,
unless I win the Vietnamese jack pot which is only about
maximum 100,000 USD.
And, If I do win at the lottery,
I will invest that money on my return to my home country Canada.
That's it for now.
Any comments, suggestions are all welcome
or if you want to share your win at the lottery,
that's O.K. with me.

Guy 13
 

If insulation and wood are available there you can make your own bass traps.  12" of rockwool or fiberglass or cotton insulation in a 48"x24"x12" frame covered in burlap will work fine as a bass trap.

[Guy 13]

If insulation and wood are available there you can make your own bass traps.  12" of rockwool or fiberglass or cotton insulation in a 48"x24"x12" frame covered in burlap will work fine as a bass trap.

Hi Letitroll98 and all Audio Circle members.
I know exactly how to make a bass trap.
(I've learned it after spending several dozens of hours on the net.)
My problem is not the wood,
it's the rockwool or fiberglass or cotton insulation,
it's not available in Vietnam.
(I spent many days searching for a place where they sell it.)
I have to import it and that's expensive...
That's why I am waiting to win at the lottery.
Thanks for the suggestions.
By the way, even if you give me free of charge some
finished/assembled bass traps,
I still have to pay for transport and custom tax
and even that, right now, I cannot afford.

Guy 13

[Guy 13]

OK, first please clarify.  You state that background noise is 40 dB, so should your chart be read as 40 dB higher than the stated readings?  (That would place them up to 130 dB, which should be painfully loud.)  If not, how do you have readings below 40 dB?  And how is it that those 4 good sized woofers (not familiar with your speakers) are 30 dB down at 50 Hz?  Do you listen near field (where the mike is shown)?  Why not measure from where you listen?  Not sure if your speakers are dipole or bipole, or if near field testing makes sense/works with either design.

My first attempt used a Radio Shack analog meter with Stereophile CD test tones, but got better results using a Behringer DEQ 2496 with ECM microphone (both from my near field listening position).  Do you know how accurate your signal generator and/or meter are?  (Radio Shack meters have well documented inaccuracies, especially at lower frequencies.)  I also recommend doing each channel separately (my matched drivers varied in my nearly symmetrical room by up to 6.5 dB).

As I've stated before, the room acoustics priorities should be: speakers (duh); proper room (bigger is better with good length/width/height ratios to avoid reinforcing echo); treatments (but don't over do as we're conditioned to listen to 'typically furnished' rooms); EQ (only as a finishing touch). 

Read Floyd E. Toole's 'Sound Reproduction'.  It recommends a variety of good room ratios, touches on treatments, and pushes the need for having multiple subs.  Without multiple subs no room will produce flat bass response, except in particular locations at particular frequencies.

Hi JLM and all Audio Circle members.

{{ OK, first please clarify.  You state that background noise is 40 dB, so should your chart be read as 40 dB higher than the stated readings?  (That would place them up to 130 dB, which should be painfully loud.)  If not, how do you have readings below 40 dB? }}
 
With everything off, I read 40db.

{{ And how is it that those 4 good sized woofers (not familiar with your speakers) are 30 dB down at 50 Hz? }}

Search me, don’t know ? ? ? 

{{ Do you listen near field (where the mike is shown)? }}

Yes !

{{ Why not measure from where you listen? }}

That’s what I am doing.

{{ Not sure if your speakers are dipole or bipole, }}
 
They are equivalent of the V1 from Danny Richie GR Research.
Open baffle, H frame.

{{ or if near field testing makes sense/works with either design.}}

{{ My first attempt used a Radio Shack analog meter with Stereophile CD test tones,
but got better results using a Behringer DEQ 2496 with ECM microphone
(both from my near field listening position). 
Do you know how accurate your signal generator and/or meter are? }}
 
Definitely more accurate than a Radio scrap meter…

{{ (Radio Shack meters have well documented inaccuracies, especially at lower frequencies.)  I also recommend doing each channel separately (my matched drivers varied in my nearly symmetrical room by up to 6.5 dB). }}

Yes, maybe I will do that next Sunday.

{{ As I've stated before, the room acoustics priorities should be: speakers (duh); proper room (bigger is better with good length/width/height ratios to avoid reinforcing echo); treatments (but don't over do as we're conditioned to listen to 'typically furnished' rooms); EQ (only as a finishing touch). }} 

I agree.

{{ Read Floyd E. Toole's 'Sound Reproduction'.  It recommends a variety of good room ratios, touches on treatments, and pushes the need for having multiple subs.  Without multiple subs no room will produce flat bass response, except in particular locations at particular frequencies. }}

I have two (02) extra Rythmik Servo sealed sub woofer model F12G,
I will try that as soon as I get the repaired Rythmik plate amplifier.

Thanks for the info, I know that I still have some homework to do.

Guy 13

[JLM]

Thanks, but still confused. 

Do the readings on your graph include the 40 dB background?  (If so, how do you get readings under 40 dB?)

If the readings on your graph have the 40 dB background subtracted, you seemingly would have been listening to peaks of 130 dB (painfully loud).  Which is it?


Next question:  are your speakers dipole (both woofers fire in the same direction at the same time), or bipole (one woofer fires forward as the other fires backwards on each speaker)?

If dipole, it seems to me that near field measurements (or listening) aren't going to be realistic/recommended as the in/near the plane of the speakers the front and back out of phase waves cancel each other out.

[Guy 13]

Thanks, but still confused. 

Do the readings on your graph include the 40 dB background?  (If so, how do you get readings under 40 dB?)

If the readings on your graph have the 40 dB background subtracted, you seemingly would have been listening to peaks of 130 dB (painfully loud).  Which is it?


Next question:  are your speakers dipole (both woofers fire in the same direction at the same time), or bipole (one woofer fires forward as the other fires backwards on each speaker)?

If dipole, it seems to me that near field measurements (or listening) aren't going to be realistic/recommended as the in/near the plane of the speakers the front and back out of phase waves cancel each other out.

Hi JLM and all Audio Circle members.

{{ Thanks, but still confused. }} 

Let me try to unconfused you.

{{ Do the readings on your graph include the 40 dB background?  (If so, how do you get readings under 40 dB?) }}

First: Where do you see on my graph a reading below 40db?
20-28-32Hz is shown as 40db, but there are not measurable with the SPL, so I show those frequencies as 40db, which is the ambient room noise.
I cannot hear the sound, even if the driver’s cones are moving a little.
Those Eminence Acoustinator drivers start at around 43Hz, all frequencies below that are hardly reproduced. 
Second: My reading are including the ambient noise of 40db, which was shown on my SPL meter when everything is off, therefore, the SPL meter has included in the reading the ambient noise.
Are less confused now?

(( If the readings on your graph have the 40 dB background subtracted, you seemingly would have been listening to peaks of 130 dB (painfully loud).  Which is it? }}

It’s certainly not 130db otherwise I would still be in pain with my ears.


{{ Next question: Are your speakers dipole (both woofers fire in the same direction at the same time), or bipole (one woofer fires forward as the other fires backwards on each speaker)? }}

Then it’s bipole, because they fire in opposite directions and are at 5 feet from the back wall.

{{ If dipole, it seems to me that near field measurements (or listening) aren't going to be realistic/recommended as the in/near the plane of the speakers the front and back out of phase waves cancel each other out. }}

The waves of the driver firing at the back wall come back with a delay; therefore, they should not cancel the waves of the front driver.
Does that make sense to you what I wrote?

I hope this helps, if not, ask me again and I will try again.
Hope this ping pong questioning won’t last until next year,
because one of us with give up first and I don’t think it will be me,
because I can be very patient and I hope to learn something from you.

Guy 13

[Vulcan00]

Ethan:

I want to commend you on your "Room Measuring Primer".  I used one of your earlier write ups when I was setting up my room measurement system and it was very helpful. This must be a new presentation of what I used. The attention given in this newer presentation to "Interpreting the results" is excellent!!! You hit the basics and is best primer I've seen. Thank you very much! Your presentation of this room measuring primer is concise, neatly presented, easy to follow and understand. Your write -up is most helpful for the understanding of room measurement. I think you should be commended for your educational efforts in this very important area.

Thank You

[JLM]

Thanks Guy, just had a hard time reading the left edge of your graph (it's partially cut off on my screen).


Glad to find out they're bipoles (acting like a 360 degree source) as that makes more sense to me, especially for near field listening.  Surprised that those drivers don't go lower, OTOH there's no cabinet to help either.


BTW it's still 2013 here but 2014 there, so Happy (non-chinese) New Year.

[Guy 13]

Thanks Guy, just had a hard time reading the left edge of your graph (it's partially cut off on my screen).


Glad to find out they're bipoles (acting like a 360 degree source) as that makes more sense to me, especially for near field listening.  Surprised that those drivers don't go lower, OTOH there's no cabinet to help either.


BTW it's still 2013 here but 2014 there, so Happy (non-chinese) New Year.

Hi JLM and all Audio Circle members.
Sorry about my louzy chart,
Next time I will try to do better.
Below are the specs of my sub woofers.

Eminence Acoustinator N2012 Neo 12" Guitar Speaker 8 Ohm
Specifications: • Power handling: 150 watts RMS • VCdia: 2" •
Impedance: 8 ohms • Frequency Range: 40-3,500 Hz •
Sensitivity: 94.7 dB 1W/1m • Magnet weight: 7 oz.

Those were purchased from Danny Ritchie GR Research for a V2 kit.
As usual, I made some modifications to the original design.

I will do more acoustic tests, however, it will be with the same measuring instruments.

Next step would be the purchase of bass traps,
absorber and diffusers, unfortunately,
that might never happen.
I have to accept that fact
and enjoy as much as possible what I have now,
which is not that bad after all.

Guy 13

[Ericus Rex]

Hi Guy,

Since you can't get room treatments in Vietnam maybe you could do some improvising with the materials you do have.  Like covering the walls with thick tapestries.  This might not work as well as GIK treatments but it should offer some improvement.  Corner traps will require a bit more creativity.  Maybe large sculptures in the corners?  Preferably geometric ones that would diffuse the bass a bit?

[opnly bafld]

Guy's speakers are OB dipole, woofers are wired out of phase.

Lin

[Guy 13]

Hi Guy,

Since you can't get room treatments in Vietnam maybe you could do some improvising with the materials you do have.  Like covering the walls with thick tapestries.  This might not work as well as GIK treatments but it should offer some improvement.  Corner traps will require a bit more creativity.  Maybe large sculptures in the corners?  Preferably geometric ones that would diffuse the bass a bit?

Hi Ericus Rex and all Audio Circle members.
A new year is beginning with all it's joy and sadness,
let's hope that 2014 will have more happiness than sadness.
I wish you (Maybe I've done it already, I forgot)
a Happy New Year
and everything your hart desire for the years to come.
Thanks for your comments.
I am always looking for some places where to buy audio stuff,
including acoustic treatment raw material.
I already have four (04) draperies on each wall of my listening room,
they are each 6' X 6" and quite tick, unfortunately,
the material look more reflective than absorbing,
according to what I can see, I might be wrong.
I already found a store where they sell the styrofoam diffusers,
but according to some Audio Circle members,
stryrofoam is not hard enough
and I need more absorber/bass trap than diffuser.
I don't give up, I still look...
Thanks.

Guy 13

[Guy 13]

Guy's speakers are OB dipole, woofers are wired out of phase.

Lin

Hi Lin and all Audio Circle members.
May I ask what is the meaning of your nickname Lin.
The above is correct.
Did I not mentionned that in my original post ? ? ?
Thanks for mentionning.
Happy New Year.

Guy 13