[bdiament]

Hi Tony,

...I definitely have a long resonance at 55hz, and a huge null at 170hz (guessing its mic height on that one)
I'll gather some pictures and some of these initial plots, before I settle in on the final testing placement.  The room is bare except for a small set of plastic drawers, which I will move out.  Also there is a closet door, metal, with extra sheets and blankets and such in there. If I measure drywall to drywall its a beautiful dimensioned 13x13x8 room...

The issue at ~170 is not related to the mic height.  It is exactly where I would expect a severe issue in a 13 x 13 foot room.  (Were the initial 11 x 10 measurements of another room?  Or just a mistake?)

As I said earlier, a square room is harder to treat than a non-square room, i.e. it isn't going to show much with only a few traps:

"I'm not so sure a room with such close dimensions, a considerably more difficult room because of this, will necessarily reveal more about two absorbers since they have a more difficult task to do than they would if the room was similarly shaped to his normal room but just smaller."


Quote from: TRADERXFAN on October 20, 2009, 03:36:39 PM
...I think when I do the bare room sweeps it will show modal problems under 100 hz...

"Assuming speakers with a relatively flat response (and of course, a mic with a flat response), I don't believe that is where the biggest issues in that particular room will be though."

Looking forward to seeing more results.
But it seems you are not getting to listen to the variations with music, while you do the testing.  It this correct?  If so, I submit that when it is all done, you will learn a whole lot more by trying these things while listening to music.  Perhaps infinitely more.  I wonder what you might have learned or what conclusions you might have drawn from these tests so far? 

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[Ethan Winer]

Not sure why the waterfall cut off early. The frequency plot went to 500hz.

When the waterfall display is showing, click the Graph Limits button near the upper right to set the frequency and dB ranges.

--Ethan

[TRADERXFAN]

updated some waterfalls.
Corrected the range.
added overlay of bare room for comparison.

Note: The "ob" designation is for a mains speaker, the RAW "OB2X", which is ported at 50hz.

I am not going to listen to music at this stage. I am trying to discover the "bass trapping" properties of the different approaches.  I understand there are other attributes to these approaches at different ranges, and purposes.   Again, I am mainly interested in them to be used as bass traps. My rationale is that there are many ways to control the upper frequency problems.

On a separate note, I did receive my copy of the master handbook of acoustics last week, and this has greatly improved my awareness of a few issues and techniques.  Highly recommended reading for anyone interested in getting the most out of your system.  It is a bit technical, but plenty to be gleaned without going into the math. I am a visual person and there are tons of visual representations.

(Prior to this, most of what I learned came from Ethan's site, thanks Ethan!  And a few other concepts from Earl Geddes' site  and home theater book @ Gedlee.com)

I started to assemble the pipe insulation.  So hopefully I'll get that done and start really testing some things by next weekend.

-Tony

[TRM]

updated some waterfalls.
Corrected the range.
added overlay of bare room for comparison.

thanks for the update.

the unopened bags seem to be fairly effective, considering the 'quick & dirty' approach and the cost.

what treatments were used on the last graph? sorry having trouble deciphering and I didn't see it listed elsewhere in the thread.

[TRADERXFAN]

This one? "servo 4 min wool 2 high stack tricorners blue overlaid with bare room whitish"

This is my labeling scheme
"servo" is referring to the subwoofer, "ob" to a mains speaker ported 50hz.

"4 min wool" refers to four, mineral wool 2'x4' panels, up to now all are 6 in thick and 8 # density.

"triconer"is just standing up in the corner of the room. assume front corner unless I specify.
"2 stack high" just saying 2 panels stacked up to the ceiling. Alternatively, assume its just on the floor.
I don't have any mounting for any of these, but may try that down the road.

"Box" is something that I experimented with having 2 panels standing straight up making a box with the corner, thought maybe we would see some deeper bass effect since they were further spaced.

Is that easy to follow? Any suggestions on making it clearer?

I wanted to get some preliminary graphs done to make sure I have all my bases covered for when I have to do the pipe tubes, and will probably not be able to go back and redo them after being filled and sealed . Although, I am thinking of cutting plastic and taping it over the tops and bottoms to make it airtight, and then set the mdf tops on it, for rigidity, and not actually glue it up at this point.  I used duct tape on the sides, of the first two that on which I have started, to connect the cylinder halves.

I am going to pull the pictures  I have taken off of the disk and load a couple to help clarify the room setup.

-Tony

[TRADERXFAN]

I would be interested to hear if others deem these few examples of differences from the bare room to be significant?  It doesn't seem like it to me... maybe I am not looking at the scale properly?

-Tony

[terry j]

http://www.acousticsciences.com/matt.htm


You can record it and look at the waveforms to see how much decline there is in the signal between the pulses.



Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

This is a slight tangent, Barry, can you give a quick rundown on how *we* might be able to use the MATT tones? (if you are up to it, perhaps a seperate thread/tutorial might be best??)

I downloaded them quite a while back, there was a rather long article on the asc site I think where the guy showed the recorded/decoded waveforms of the signals before and after treatment.

I got stuck at the 'how do I record that' - well I knew I could use that free program (forget it's name right now) and record it with my mic, but I had no idea how I could see it's waveform. that prob doesn't make sense, but I hope you can help.

It did seem to me to be a very useful test...if it could be done.

[TRADERXFAN]

ASC makes what they call a MATT (music articulation test tone) that you can find on Stereophile test CD #2.  This is an excellent signal for checking the effects of room issues (and treatments).  Listening to the MATT via headphones, then via your speakers (with and without treatments or with treatment A, then treatment B) will be an education in itself.  The headphones of course, will give you the tone without room effects.  After hearing this, you'll find it a lot easier to hear what the room/treatments do in between the pulses of the tone.

There was a link to this test tone to download, and some other tutorials on how it should be used. 

I don't think its something that I could really measure. I will use the signals available on the room eq wizard software, periodic pink noise, sinewave plots, and waterfall.

-Tony
http://www.acousticsciences.com/matt.htm

Here was post earlier, with a link to a tutorial. 
This is how they recommend it be used
"The clean signal is best audited over a set of headphones. The signal path distortion is minimal with this type of acoustic coupler. Once the rapid set of distinct ascending and descending tone bursts are familiar, take the headphones off and listen to the room acoustic playback version of the same signal."

-Tony

[bdiament]

Hi Tony,

I would be interested to hear if others deem these few examples of differences from the bare room to be significant?  It doesn't seem like it to me... maybe I am not looking at the scale properly?

-Tony

Not to me either.

That is why I suggested using listening tests and precisely why, after I looked at the waterfall plots, I asked what you might have learned or what conclusions you might have drawn from these tests so far. 

If the purpose of these tests is "to discover the 'bass trapping' properties of the different approaches", I submit this particular path won't take you to that discovery.  (Sorry that though I tried to suggest this in earlier posts, it didn't occur to me earlier to phrase it this way.)

To be clear, I'm not by any means suggesting you stop.  I support and encourage any and all efforts to find what makes a given listener get more from their system.  In my experience, some roads to this are considerably shorter and some considerably longer, than others.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

[bdiament]

Hi Terry,

http://www.acousticsciences.com/matt.htm


You can record it and look at the waveforms to see how much decline there is in the signal between the pulses.



Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

This is a slight tangent, Barry, can you give a quick rundown on how *we* might be able to use the MATT tones? (if you are up to it, perhaps a seperate thread/tutorial might be best??)

I downloaded them quite a while back, there was a rather long article on the asc site I think where the guy showed the recorded/decoded waveforms of the signals before and after treatment.

I got stuck at the 'how do I record that' - well I knew I could use that free program (forget it's name right now) and record it with my mic, but I had no idea how I could see it's waveform. that prob doesn't make sense, but I hope you can help.

It did seem to me to be a very useful test...if it could be done.

As Tony quoted from ASC's literature, listening to headphones will tell you what the MATT tone, specifically the "silences" in between the pulses really sound like.  Comparing this to what you hear from the listening position via your speakers (with and without room treatments) will be quite informative.

By the "free" program, are you referring to Audacity?
That will probably do the trick in allowing you to record the MATT tone and see in the waveform, how your room "fills in" the spaces.
You can also directly extract the tone from the CD as a file (bypassing the mic, the speakers and your room) to see what it looks like without room distortions added.

In my view, this (i.e. actually hearing it) will be infinitely more informative and educational (not to mention fast) for the typical audiophile than volumes of numeric or graphical representations. 

Just my perspective.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[TRADERXFAN]

Hi Tony,

I would be interested to hear if others deem these few examples of differences from the bare room to be significant?  It doesn't seem like it to me... maybe I am not looking at the scale properly?

-Tony

Not to me either.

That is why I suggested using listening tests and precisely why, after I looked at the waterfall plots, I asked what you might have learned or what conclusions you might have drawn from these tests so far. 

If the purpose of these tests is "to discover the 'bass trapping' properties of the different approaches", I submit this particular path won't take you to that discovery.  (Sorry that though I tried to suggest this in earlier posts, it didn't occur to me earlier to phrase it this way.)

To be clear, I'm not suggesting you stop.  I support and encourage any and all efforts to find what makes a given listener get more from their system.  In my experience, some roads to this are considerably shorter and some considerably longer, than others.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

Barry, do you expect the sealed hollow pipe insulation to make a more significant effect on these waterfall plots, with the 2x 16" and 2x 20" x3 foot sections?  I can't justify 12 pieces of everything to make it really show up, as in Ethan's data set on 701, 703, and FRK. (And just the fact that it took 12 pieces made me wonder if the term bass trap is a bit of a misnomer... especially after reading the Everest book.)

Thanks everyone for the input.

-Tony

[bdiament]

Hi Tony,

Hi Tony,

I would be interested to hear if others deem these few examples of differences from the bare room to be significant?  It doesn't seem like it to me... maybe I am not looking at the scale properly?

-Tony

Not to me either.

That is why I suggested using listening tests and precisely why, after I looked at the waterfall plots, I asked what you might have learned or what conclusions you might have drawn from these tests so far. 

If the purpose of these tests is "to discover the 'bass trapping' properties of the different approaches", I submit this particular path won't take you to that discovery.  (Sorry that though I tried to suggest this in earlier posts, it didn't occur to me earlier to phrase it this way.)

To be clear, I'm not suggesting you stop.  I support and encourage any and all efforts to find what makes a given listener get more from their system.  In my experience, some roads to this are considerably shorter and some considerably longer, than others.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

Barry, do you expect the sealed hollow pipe insulation to make a more significant effect on these waterfall plots, with the 2x 16" and 2x 20" x3 foot sections?  I can't justify 12 pieces of everything to make it really show up, as in Ethan's data set on 701, 703, and FRK. (And just the fact that it took 12 pieces made me wonder if the term bass trap is a bit of a misnomer... especially after reading the Everest book.)

Thanks everyone for the input.

-Tony

The term isn't a misnomer (at least for some types of devices).  The fact is that what we're attempting to control is big and contains a great deal of energy.  I said from the start that I don't expect to see much change with only a few devices - most especially in a square room, where the issues in one dimension are mutually reinforcing with those in another dimension.

I most definitely expect properly designed sealed hollow traps to have a significantly greater effect (that's an understatement) - when used in sufficient quantities. 

As to the waterfall plots, in this particular set of tests, I don't believe they'll show you what the different devices can (or cannot) do.  For them to show you this, each of the different devices would have to be used in such a way as to actually effect a real change in the sound of the room.  Again, any room would require a good deal of devices to control this sort of energy.  A square room makes things that much harder and makes fewer than a sufficient quantity, that much more ineffective.

In my opinion, if a small quantity is going to tell you anything at all (and that remains questionable in my view), it is only going to do so with real music with which you are familiar, in the room in which you normally listen.  Even here, it seems to me a bit like trying to determine what swimming feels like by spraying mist into the air.  You can take humidity readings all you like but you still won't be any closer to knowing what swimming feels like.  I sincerely feel the only way you'll really find out will involve getting wet.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[TRADERXFAN]

Well, by misnomer, when I think of a "trap" its something that contains, like a bear trap! Where this insulation seems more like "bass inconveniences"... like something that slows you down but far from being anything resembling containment. 

From the Everest book when they reference a bass trap they say perhaps the term should be reserved for a particular reactive cavity absorber. They show a significantly large, deep, moderately insulated "nook" which is tuned, and give an example of making them 7 feet deep which attempts to control the lowest 2 octaves.

-Tony

[bdiament]

Hi Tony,

Well, by misnomer, when I think of a "trap" its something that contains, like a bear trap! Where this insulation seems more like "bass inconveniences"... like something that slows you down but far from being anything resembling containment. 

From the Everest book when they reference a bass trap they say perhaps the term should be reserved for a particular reactive cavity absorber. They show a significantly large, deep, moderately insulated "nook" which is tuned, and give an example of making them 7 feet deep which attempts to control the lowest 2 octaves.

-Tony

In view of the devices you've tried so far, I can understand your feelings.

The type I favor are based on Harry Olsen's pioneering work.  He referred to them as "functional sound absorbers", understanding they lower the Q of a room mode and do not "contain" or remove it, which, regardless of anyone's market-speak, just isn't going to happen.

Everest came from a studio construction perspective and while those deep cavities he described will certainly do the job, they are not practical in most installations, particularly home installations, where construction is already complete and they are not necessary in view of the effectiveness of Mr. Olsen's devices.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[Browntrout]

I'm no expert. Surely the differnces illustrated at around 80hz and those in the voice band between 150hz and 250hz would be easily noticable when listening to music?
  I would love to hear what you report from listening to music with the wool in the corners as this is roughly what I have and the whole 'focus point' of the music lowered noticably. Thanks for posting the graphs, is it possible to skew the viewing angle to one side slightly so the time aspect becomes more apparant? If not don't worry.

[TooManyToys]

I haven't been around much, but of the more recent threads this was going to be interesting.  Did it die of technical difficulties?

[TRADERXFAN]

Not dead. Just taking time to put together. It will happen, but going to be a few weeks.

-Tony

[arthurs]

Same here, I have a lot of other things to finish on my room remodel before I get to tube comparisons...probably Christmas for me...

[TooManyToys]

Not dead. Just taking time to put together. It will happen, but going to be a few weeks.

-Tony

Thanks Tony.  Understand completely. 

[seth411]

I was very excited when I started reading this thread then got to the end .  But thought I would respond because I am in the middle of making tube traps from 4 owens corning pipe insulation off craigslist, 15" Diameter by 3' tall 1" thick tubes. 

My plan is to make 8 corners and 4 half's all made with 1/2" thick plywood Sides, tops and bottoms, caulked screwed, and covered with material.

I've made three half's so far and have the rest of the materials to finish the project tomorrow. 
I have an ECM 8000 and will use Fuzzmeasure to run my test before and after installation.

I'll finish my tubes and post my results, but before I finish my tubes, dose anyone know if I should really spend the money and time to fill them with insulation?  Or should I just finish them?  I'd really rather just finish them but thought I'd get some opinions first.

And thanks Ethan if you read this all your articles and funny videos have helped a lot!