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Which ETC-curve should be preferred? Studio Monitors
Old 15th July 2014
  #1
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Which ETC-curve should be preferred?

In general, can anything be said which would be the preferred ETC-curve, the green #8 or purple # 12? I lean towards the purple one. For the green one, the strongest reflection back comes a bit later though which is good, on the other side it is a bit weaker than the purple one … I shall try to hunt down remaining higher dB-reflections prior to about 15 ms, they are some sneaky bastards.

The waterfall and decay curves are extremely similar for both measurements, quite even from low to high frequencies. A bit on the dry side as there is a wall to wall carpet for comfort. There are dips which varies a bit in frequency and strength due non identical mic-LP distances, -so different SBIR response in the curves. The null around 83 Hz is of little consequence for now, it is due to subs on opposite sides of the rooms center line, in combination with the listening position. When I set up an active filter for the subs and connect them in different polarity + some time delay between them, I expect the null flatten out. (The room itself is a solid concrete bunker with a symmetrical setup, 786x419x225 cm, not really meant for any production, more for pleasure.)
Attached Thumbnails
Which ETC-curve should be preferred?-etc-green-8.jpg   Which ETC-curve should be preferred?-etc-purple-12.jpg   Which ETC-curve should be preferred?-frequency-response-40-400-hz.jpg   Which ETC-curve should be preferred?-waterfall-12.jpg   Which ETC-curve should be preferred?-spectrogram-decay-12.jpg  

Old 15th July 2014
  #2
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akebrake's Avatar
 

Quote:
Originally Posted by Adhoc View Post
In general, can anything be said which would be the preferred ETC-curve, the green #8 or purple # 12? ………..
Hi Adhoc!
These reflections are more than 20 dB down... (on the ETC graph)
Do you really hear a difference?
What do the spectrum level look like or filtered ETC?

Would you mind posting the IR (wav) ?

Cheers

Ake
Old 15th July 2014
  #3
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I don't see enough difference from one ETC curve to the other to matter much.

If you want better curves, I would suggest going to -25db or -30db out to 20ms, and finding a way to encourage more and stronger reflections between 20ms and 30ms arriving laterally.
Old 15th July 2014
  #4
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Hi Ake, no I can’t hear a difference right now, -the room is in a kind of mess and I am only checking with sweeps in REW to check various possibilities to cut down reflection strengths early in time. One small addition at a time with notes taken. The hope is to find a way of getting a stronger return later in time than now (about -14,7 dB at 15,9 ms) while surpressing the earlier ones, as Jim1961 wrote. It feels like when you fix something a new situation pops up and one has to that in a Catch 22 scenario.

So far the conclusions are; avoid wooden frames for clouds if clouds are right above you and even as a small change as 5 cm / 2” speaker –mic at distance 384 cm / 12,6 feet can make a difference of several dB for SBIR response. What is surprising is that RT60 (Topt) in REW show a slow but steady increase from about 250 Hz up to 10 kHz. I am happy about the decay time in the bass, seems like the laid down work on fixes has paid off . How to increase decay time between 200-300 Hz and a bit up will be a hard nut to crack I think.
Attached Thumbnails
Which ETC-curve should be preferred?-ir-purple-12.jpg   Which ETC-curve should be preferred?-ir-green-8.jpg   Which ETC-curve should be preferred?-rt60-topt-1-14.jpg  
Old 16th July 2014
  #5
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I suggest you dump those ETC graphs and go back and get graphs filtered by octave

500hz
1000hz
2000hz
4000hz
8000hz

Thats where the meat of the matter is. You could have issues in any of those areas and they will not show up on the full bandwidth graphs you have now.
Old 16th July 2014
  #6
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Quote:
Originally Posted by Radial185 View Post
I suggest you dump those ETC graphs and go back and get graphs filtered by octave

500hz
1000hz
2000hz
4000hz
8000hz

Thats where the meat of the matter is. You could have issues in any of those areas and they will not show up on the full bandwidth graphs you have now.
Totally agree here.

Like I did here https://www.gearslutz.com/board/7186699-post71.html

and also show in the ETC up to 10ms so we can see the early reflection more closely, like this. https://www.gearslutz.com/board/9664574-post182.html
Old 17th July 2014
  #7
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Thanks for the advice Radial185, can you elaborate please? I have started to use REW quite recently, still a lot to learn about the possibilities and options it can serve you with, as long as you are aware of them. With filtered graphs, I guess you mean to zoom in on the time axis for the peak, go through the different filter options and where the filtered out frequency coincides with the peak, -you have found the frequency causing the reflection peak. After that you can apply the most suitable acoustical fix at the found reflection point, be it a small resistive absorber, pillow or perhaps a small CD-case for redirection away from listening spot. Correct, or do you mean something different?

The response within 10 ms is quite decent. The peak at 5 ms is caused by a nearby CD-rack, the one at 2,5 ms by nearby “stuff”, so easy to move away. Trickier with those at and below 1 ms which should be from edge diffractions from the side of the speaker and horn mouth. The reflection which eludes me so far is a one at 14,4 ms = 4,9 m / 16,1 feet extra travel length with -17 dB. It is somewhere in front but checked with Hannes /SAC’s “string metod” it cannot be a 1-way bounce, it has got to be a 2- or 3-way bounce between hard surfaces and my arms are not 2,5 m long and only 2 to connect that many places. Another thing is that acoustical centre does not necessarily coincide with the front of the speaker (and I believe may also vary with frequency), so this has to be considered for the ms and lengths you get from REW when the “string metod” is used. The peak at 6,18 ms = 210 cm / 6,89 feet for the green curve in the picture below comes from a plywood sheet placed parallell to the front speaker and placed 108,5 cm behind the mic => 217 cm reflection length corresponding to 6,38 ms with c = 340 m/s. Measured with laser the distance from speaker front to microphone is 3244 mm and to the plywood sheet 4331 mm. So, my conclusion is that one has to take this 7 cm / 2,75” difference in consideration when using the “string method” to find where the reflection points are. (The red curve is a similar measurement with the plywood sheet taken away, so a lot lower reflection at 6,18 ms from REW.)

Mctwerp, I checked your pictures / diagrams. Some good examples of how to show things when you want to hide things and details. –Why else 1/3 octave in the diagrams when REW can show 1/48, why axis which are way off to show any details? I guess good for marketing guys but no, not really for information.
Attached Thumbnails
Which ETC-curve should be preferred?-140715-15-16-acoustic-centre-string-method-10-ms.jpg   Which ETC-curve should be preferred?-140715-15-acoustic-centre-string-method-10-ms.jpg   Which ETC-curve should be preferred?-140715-16-acoustic-centre-string-method-10-ms.jpg  
Old 17th July 2014
  #8
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If the ETC is unfiltered, it can be considered broadband. It's like looking at white noise versus looking at a sine wave.
Old 17th July 2014
  #9
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Adhoc,

If you are using REW, the option is in the bottom left of the ETC display,from memory. There you can choose the frequency bands you want to look at. Keep your graph axis the same while flicking through them.
Old 17th July 2014
  #10
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Opus, is below what you mean?

Edit: Oops, poor headline for the first diagram. Shall try with sweeps narrower in range too.
Attached Thumbnails
Which ETC-curve should be preferred?-140715-etc-16-filtered-8000-hz-peak-spot-.jpg   Which ETC-curve should be preferred?-140715-etc-16-filtered-4000-hz-peak-off.jpg  

Last edited by Adhoc; 17th July 2014 at 01:36 AM.. Reason: poor headline i diagram
Old 17th July 2014
  #11
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Yes, that is a much more informative display than the unfiltered results. (for the band)

Was that a sweep of a narrow range, or did you filter it?

I think you need to enlarge the displayed time range, for clarity.
Old 17th July 2014
  #12
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It is the very same measurement, 20-20 000 Hz, as for Envelope in post # 7, only displayed in IR and filtered there.

Time for bed now

Last edited by Adhoc; 17th July 2014 at 12:34 PM.. Reason: forgot a word
Old 17th July 2014
  #13
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Quote:
Originally Posted by OpusOfTrolls View Post
Yes, that is a much more informative display than the unfiltered results. (for the band)

Was that a sweep of a narrow range, or did you filter it?

I think you need to enlarge the displayed time range, for clarity.
What do you mean by this Opus? Should we not be using full range sweeps when determining ETC?
Old 17th July 2014
  #14
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Quote:
Originally Posted by Radial185 View Post
What do you mean by this Opus? Should we not be using full range sweeps when determining ETC?
Did I say that?
Old 17th July 2014
  #15
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Bobecca's Avatar
 

Adhoc...

Your room is heavily treated if memeory serves me correct here and despite of that, your responses and ETC is realy bad if you ask me.

Why the unevenees in your graph showing RT60. The ETC is also uneven and lots of reflections that has to be taken care of. Freq response......dont let me have to go there.

With that amount of treatment you have put in your room and to have the responses you are showing only makes me wonder how you can be happy about your achievement.

Are you not happy with the result?
Old 17th July 2014
  #16
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akebrake's Avatar
 

T opt drop...

Quote:
Originally Posted by Adhoc View Post
Hi Ake, no I can’t hear a difference right now, -the room is in a kind of mess and I am only checking with sweeps in REW to check various possibilities to cut down reflection strengths early in time. One small addition at a time with notes taken. The hope is to find a way of getting a stronger return later in time than now (about -14,7 dB at 15,9 ms) while surpressing the earlier ones, as Jim1961 wrote. It feels like when you fix something a new situation pops up and one has to that in a Catch 22 scenario.

So far the conclusions are; avoid wooden frames for clouds if clouds are right above you and even as a small change as 5 cm / 2” speaker –mic at distance 384 cm / 12,6 feet can make a difference of several dB for SBIR response. What is surprising is that RT60 (Topt) in REW show a slow but steady increase from about 250 Hz up to 10 kHz. I am happy about the decay time in the bass, seems like the laid down work on fixes has paid off . How to increase decay time between 200-300 Hz and a bit up will be a hard nut to crack I think.
Adhoc, the HF reflection at 1 ms (above 4kHz) is interesting. Try to isolate it by measuring closer to the speaker to find out IF it's the speaker or something else.

IMHO you may concentrate on (dare I say …) ”reverb time”, huh
E.g. Why this Topt drop from 200 Hz up to 1 k?

Couple of questions:
1. Are the room still like post #154 in Tims Limp Mass Thread?

https://www.gearslutz.com/board/8106306-post154.html

2. Are the Topt curves from the same microphone position?
3. Are there large areas of ”bad” and soft panels in the room?
4. Are you hunting for a "reference" ETC from another room?

Side remark
As everybody have different ideas how to display or tweak measurements I am asking you kindly to export and post IR from each (new) measurement.
REW Menu: File> Export> Impulse Response as WAV
Pls use 44.1 kHz for measurements (works for Mac users like me )
That will also make it possible for other software users (Fuzz or ARTA) to help.

Ake

PS. Which REW version do you have? 5.01 B 23?
Old 17th July 2014
  #17
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Apparently there was a glitch in REWs presentation of #16 SPL & Phase but there were no problems in IR and Envelope. Made a new measurement #17 (yellow) today. Nothing has changed in the setup itself, it was left hooked up from yesterday.

Bobecca, your comments reminds me of AA Milnes Winnie-the-Pooh. Unfortunately, as nice as he may be, that bear has a very limited brain capacity. To keep that in mind, I think I shall remember you as Poohbecca instead of Bobecca, -seems to be a more suitable nick, just as Mctwerp might be for your brother Mctwins.

Do you mean I should present graphs as your brother Mctwerp has, with 1/3 octave and axis limits way off to actually reveal anything of interest? Like the pictures below with the very same measurement presented A) as Mctwerps has or B) in a more meaningful way if one wants to sort out any problems.

Akebrake, The broad dip between about 250 and 350 Hz with centre frequency around 290 Hz and about -10 dB is caused by a leather sofa in the middle of the room. The dip fades away if the sofa is placed closer to the very end of the room, -pretty efficient upper base absorber that sofa. This also seems to show off in the decay which is at lowest in this region. 1/48 and 1/3 octave shown for clarity.

The room has been modified since previous pictures. New: New subs have been installed at front and back wall and a cloud of about 2,4x1,7 m x 145 mm with Flexibatts is up in front of LP. Binary MLS slats on some resistive absorbers close to speakers have been removed to avoid early reflections. That would be new soft areas. To counter this increase in “soft area”, other binary MLS slat absorbers in regions of no early reflections have been covered up with additional slats so their open areas over insulation has decreased from 50% to about 7%. Superchunks have been added in front corners. Fronts are 89 cm / 35”wide and covered with 169x21 mm wide boards. Slot width between boards now is 5,5 mm ( 3,7%) and should increase to about 4% after the wood has shrunk a bit after being inside at room temperature a couple of months. Perhaps I will increase the slot width for the Superchunks later on. I need to wait until the wood is completely dry before doing that though. (The superchunks are open at top and bottom by the way, not built as Helmholtz absorbers). I can also readjust the slat absorbers open areas from 7% to a higher one. These are over enclosed cavities and a higher open area ratio should decrease efficiency in the upper bass / mid region. The decay time from 200 Hz or so should show an increase then and be more even with bass and high requencis. I enclose some pictures of the new front.

All graphs (almost) are from identical mic position, 384 cm from a fixed TV screen (407 cm from a concrete shell wall), along centre line of room versus length 786 cm between concrete walls. The popular spot at about 38% of room length cannot be used for practical reasons and actually also show a worse response. What I am hunting for are first reflections down to about -20dB or less during the first 20 ms or so, then as high a reflection as possible. This together with a smooth even decay rate around 0,22-0,25 ms for all frequencies. Decay rate seems fine now in the trickier lower bass region and is also OK for higher frequencies. As you have noted, it should be increased between about 250 and 1000 Hz.

Right now I am in the beginning of measurements, minor adjustments to come. The REW version I have is 5.01 Beta 21, didn’t know a Beta 23 had come out. I will check that up, thanks. I can post files later on when I am past “beginning stages”. Thanks again for your response Ake!
Attached Thumbnails
Which ETC-curve should be preferred?-140715-17-hiding-problems-1-third-octave-poorly-chosen-axis-limits.jpg   Which ETC-curve should be preferred?-140715-17-measurement-more-revealing-1-48-octave-axis-limits.jpg   Which ETC-curve should be preferred?-140715-17-1-third-octave-leather-sofa-acts-absorber-fc-290.jpg   Which ETC-curve should be preferred?-140715-glitch-measurement-16.jpg   Which ETC-curve should be preferred?-84-superchunks-forsta-lagret-spikband.jpg  

Which ETC-curve should be preferred?-86-hoger-superchunk-5-5-procent-perforering.jpg   Which ETC-curve should be preferred?-87-ny-front-med-superchunks.jpg  

Last edited by Adhoc; 17th July 2014 at 04:35 PM.. Reason: Added some text
Old 17th July 2014
  #18
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Rod Gervais's Avatar
 

Bobecca,

I don't know if you realize it or not - but the OP is not interested in either your comments or (what you might perceive as) your "assistance"......... he gives credence to neither....... and apparently he has the same feelings towards your brother.......

Perhaps you should seek greener grounds to graze on..........

Rod
Old 17th July 2014
  #19
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His sad buddy Eeyore (Ior) may graze, I have some doubts about Pooh himself grazing though.

Last edited by Adhoc; 17th July 2014 at 06:18 PM.. Reason: Ior = in Swedish books
Old 17th July 2014
  #20
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akebrake's Avatar
 

Quote:
Originally Posted by Adhoc View Post

…...Right now I am in the beginning of measurements, minor adjustments to come. The REW version I have is 5.01 Beta 21, didn’t know a Beta 23 had come out. stages”. Thanks again for your response Ake!
Your welcome!
Interesting thread showing limp mass in action! (in concrete shell)

best

Ake

Sorry, I my be wrong about the beta number... :face palm:
Old 18th July 2014
  #21
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Hallo!

It is more than enough to show in 1/3 oct band according to EBU standard. Can be read here....

"MyRoom" acoustic design

But, here you go..Adhoc

https://www.gearslutz.com/board/10270180-post373.html
Old 18th July 2014
  #22
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Adhoc.....at least I spell you usename right.

Why the bad bass response? You seem to have large subwoofers in there.
Old 18th July 2014
  #23
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Adhoc...you must have missed this.....

https://www.gearslutz.com/board/9455716-post165.html

Here, I am showing 1/48 oct band in the Freq response.
Old 18th July 2014
  #24
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Hallo!

The reason I showed the upstairs measurement in lower oct band was to see the differense better between Flower wings on the floor and without. That's all.
Old 19th July 2014
  #25
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A good part of yesterday was spent chasing reflection areas / spots, getting quite fed up with it… Last one found wasn’t larger than Ø 7,5 cm / 3” and showed out to be the projector lens. Still haven’t found the one “responsible” at 14,4 ms, it should be about the same size or smaller but a 2-bounce reflection at a high frequency. The best ETC I can seem to accomplish is in pictures below.

So, question to you knowledgeable guys, would it be worth pursuing the chase, given the result in the ETC? First stronger reflection back which are at 14,4 ms / -19,7 dB or 23,9 ms / -21,3 dB are my choices, or perhaps take both? I scratch my head when it comes to: Longer time span is better versus a higher signal back is better.

The reflection at 23,8 ms / -21 dB comes from a curved BAD-panel at the very end of the room. The curved BAD scatters reflections towards the sidewall / close corner, concentrates them as it seems before they bounce further towards the mic. If I put up a large flat plywood sheet right against the BAD panel, the reflection strength from 23,8 ms gets reduced to -23,5 dB. Placing the plywood closer to LP also reduces the strength with about 3,5 dB, angling it from the ceiling downwards gives no better result.(And no, I do not want to put up a QRD on the BAD.) The very limits = highest reflections back I have measured have been -16,9 and -18,9 dB respectively for those two times, but this will worsen other reflections in the time span and reduce the dB-margin to these.

Mctwins (yes I will call you Mctwins when you keep a standard with choice of words and opinions as above 4 posts):
A) I prefer to keep to 1/48 octave as long as it is about making decisions to improve whatever it may be. 1/3 may (still) be a standard but can blindfold you from possible problems which could actually be solved.

B) Bass response … I haven’t given it any time yet. The reason for the current lack in lower frequencies is that the boxes on purpose where built about 70 L too large. This gives a lower Q than normal 0,707 or so and a meager bass. Why that choice? Reason; it gives me several options: A) If I want to, I can change them to ported ones which necessitates larger boxes, tuned in the lower 20:ies or slightly below. The ports would have to be about 1 m long and be hidden behind the wooden boards above and below the TV. B) But ported boxes are less suitable if I want to go down into infra sound in my room, as ported falls off at 24 dB/octave and they cannot for practical reasons be tuned lower than about 20 Hz. I will not get any free pressure gain until very low frequencies because of the room length 7,86 m / 21,8 Hz. Pressure gain starts to kick in with theoretically 12 dB/octave for wave lengths longer than the rooms largest dimension. (In practice less than 12 dB and massive walls are needed as well as a well sealed room, which I have). With closed boxes falling off at 12 dB/ octave, it should be possible to get down to perhaps 10 Hz with substantial SPL with some eq / Linkwitz transform. In that case a low Q box is better to start with than a higher Q one. A large box volume also means less power is needed for max excursion, less power means less heat in the voice coil with less power compression and distortion both from speaker and amplifier which can just idle by. C) If I for any reason I wanted to, it is quite easy to take the elements out and seal off a compartment inside the box for a lower speaker volume with higher Q. Right now the subs are only connected to the .1 output on an AVR, a dbx Driverack 482 will be used as active filter later on.

C) That floor bounce spike you had at about 1,7 ms /-5 dB which was cured to -20 dB with the SMT “Flowers” was probably a high frequency one and could have been fixed with a pillow, a dead dog or so. (A stuffed cocker spaniel would be just about appropriate in size). My floor bounce is centered around 1,6 ms. With wall to wall carpet, high frequency reflections are down to -22 dB. A piece of plywood at the area raises it to -14 dB and with a 40x40 cm x 45 mm piece insulation on top of the plywood it is lowered again, now to -27 dB. To do much good for lower frequencies with longer wave lengths the “Flower” is simply too small. Tip of the day: A stiff, paws up stuffed spaniel looks way cooler than a plastic Flower on the floor I think.
Attached Thumbnails
Which ETC-curve should be preferred?-140719-etc-30-ms.jpg   Which ETC-curve should be preferred?-140719-etc-100-ms.jpg   Which ETC-curve should be preferred?-140719-spectrogram-decay.jpg  
Old 19th July 2014
  #26
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Adhoc,

I'm going to ask you a question I ask most people about this point in time...........

"When you sit and listen - are you happy with the results?"

I have a brother (Paul - one of 6 brothers *there are also 5 sisters - but Paul is not one of them) who has a listening room..... it's one room in his house with a high end sound system - and he sits in there to unwind, lay back - close his eyes - and listen to music......

The room has not a treatment in the world - and I know (as do you) that acoustically it is anything but "correct" - yet he finds great pleasure in sitting there listening to the music on his high end sound system........

Could it be "more" that what it is acoustically? Sure it could - however - for Paul - it is everything it needs to be......... thus it is "enough"

Jim (on the other hand) who visits us here appears to be on a quest for perfection........ which is also all right........

In my mind the big question comes down to personality/pleasure....... so back to the big question........

When you sit and listen - not measure - not think about software, charts, mic positioning, tweaks.......... just relax and listen....... are you happy with what you hear?

If the answer to the question is "yes" - then in my opinion you're done.......... if the answer is "no" then you need to begin planning your next move.......

A piece of software, microphone and measurement does not need to define your experience.........

Rod
Old 19th July 2014
  #27
Gear Addict
 

A very thoughtful, good advice and reasoning from you Rod. An important one to remember for those who may otherwise just waste time and money for little or no benefit.

I could be the third brother. The one who is already, all in all, quite satisfied but does not mind a project aiming for “perfection” or at least something “more”, as perfection cannot be reached but ends up in some kind of compromise. I do not mind a step towards a compromised perfection .

Reason for the project is that I decided to go also for infra sound (movies) not “only” music. The possibility is there with a well sealed solid concrete bunker, heavy doors with good seals and no windows to speak of. The hardest bit, decay in the low range is sufficiently solved. I know that from the previous ported subs which were put aside and were good down to the lower 20:ies. I now know I can also get rid of the breathable wall to wall carpet and have a wooden floor if I decide on it. When I moved in, the concrete floor was an unknown variable for moisture, -if it could fare well with wooden floor without forced ventilation. Forced ventilation was out of the question because of the low ceiling height.

Measurement gear / REW I got very recently is only for checking if the steps and ideas leads forward, sideways or backwards. I see no use for something which may look cool but gives no benefit. Lessons so far from REW-measurements for decay rates; low bass /modes are much better than expected, high frequencies OK but for upper bass and mid the absorbers are too efficient with a too low decay in comparison to both low bass and treble. I have a pretty good machine chop with cast iron machines for wood and carpentry, so I can make just about everything myself without hiring in people.

What I also have is a fiance’e with less patience than me for loooong term projects requiring listening in between each step ... What I don’t have is accumulated experience when it is suitable to stop as a next step should give little payback vs efforts in time and money. Hence my questions here at GS about the evaluation of signal strength <=> time span.
Old 19th July 2014
  #28
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Mctwins's Avatar
 

Quote:
Originally Posted by Adhoc View Post
C) That floor bounce spike you had at about 1,7 ms /-5 dB which was cured to -20 dB with the SMT “Flowers” was probably a high frequency one and could have been fixed with a pillow, a dead dog or so. (A stuffed cocker spaniel would be just about appropriate in size). My floor bounce is centered around 1,6 ms. With wall to wall carpet, high frequency reflections are down to -22 dB. A piece of plywood at the area raises it to -14 dB and with a 40x40 cm x 45 mm piece insulation on top of the plywood it is lowered again, now to -27 dB. To do much good for lower frequencies with longer wave lengths the “Flower” is simply too small. Tip of the day: A stiff, paws up stuffed spaniel looks way cooler than a plastic Flower on the floor I think.
It starts at around 200Hz but mainly from 500-1000Hz where the floor bounce(first reflection)is messing up and cause disturbance in the freq response.

Look at the waterfall between Flower on the floor and without. This good response with the Flower on the floor is due to the difference lenght in the Time delay lines that is created inside these modules.

Are you really serious in your claim that something soft will keep the energy intact in the room and pull out the incoming signal approximately 5ms??
Attached Thumbnails
Which ETC-curve should be preferred?-prx600vattenfallmedrosor.jpg   Which ETC-curve should be preferred?-prx600vattenfallutanrosor.jpg  
Old 19th July 2014
  #29
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Quote:
Originally Posted by Adhoc View Post
A very thoughtful, good advice and reasoning from you Rod. An important one to remember for those who may otherwise just waste time and money for little or no benefit.

I could be the third brother. The one who is already, all in all, quite satisfied but does not mind a project aiming for “perfection” or at least something “more”, as perfection cannot be reached but ends up in some kind of compromise. I do not mind a step towards a compromised perfection .

Reason for the project is that I decided to go also for infra sound (movies) not “only” music. The possibility is there with a well sealed solid concrete bunker, heavy doors with good seals and no windows to speak of. The hardest bit, decay in the low range is sufficiently solved. I know that from the previous ported subs which were put aside and were good down to the lower 20:ies. I now know I can also get rid of the breathable wall to wall carpet and have a wooden floor if I decide on it. When I moved in, the concrete floor was an unknown variable for moisture, -if it could fare well with wooden floor without forced ventilation. Forced ventilation was out of the question because of the low ceiling height.

Measurement gear / REW I got very recently is only for checking if the steps and ideas leads forward, sideways or backwards. I see no use for something which may look cool but gives no benefit. Lessons so far from REW-measurements for decay rates; low bass /modes are much better than expected, high frequencies OK but for upper bass and mid the absorbers are too efficient with a too low decay in comparison to both low bass and treble. I have a pretty good machine chop with cast iron machines for wood and carpentry, so I can make just about everything myself without hiring in people.

What I also have is a fiance’e with less patience than me for loooong term projects requiring listening in between each step ... What I don’t have is accumulated experience when it is suitable to stop as a next step should give little payback vs efforts in time and money. Hence my questions here at GS about the evaluation of signal strength <=> time span.
I have found, having people over and such, that people like for music for different reasons and/or look for different things from it to derive there pleasure from it.

Some people merely want to hear the melody. The nuances of the sound are not that important to them (Rod's brother).

For me, and perhaps you, the production is also important. We want the sound to be convincing, enveloping and stimulating, almost in a physical sense.

I too experienced frustration in tracking down reflections. Many more in addressing nuances all over the spectrum. Along with the frustration, I liked the challenge as well.

An analogy might be that of an art appreciator. A great painting is still satisfying to observe in a improperly lit environment. But one knows on some level that your missing some things in such an environment.
Old 20th July 2014
  #30
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Quote:
Originally Posted by Adhoc View Post
….Measurement gear / REW I got very recently is only for checking if the steps and ideas leads forward, sideways or backwards.
I see no use for something which may look cool but gives no benefit….
What kind of (objective) measurement results are you opting for?
Like: bandlimited ETC, Topt, plus FR, WTFL and more.

(To correlate with (subjective) perceived spectrum, spaciousness, stereo spread, apearant source width ASV, listener envelopment LEV and more)

I'm sure I have forgot some...

Best

Ake
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