No never measured it , but it works very, very well and no Fg dust ..
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also available at wall mart !!!
Here's the T30 response in my room. The T60 reverberation time (shown in the Energy Decay window) is 0.430 s. This is with both speakers playing and the mic in the listening position pointed upwards. Input is swept sine.
I don't really know what to make of this. What do you guys think?
I don't really know what to make of this. What do you guys think?
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Very late to the party and trending off-topic.....
Pano -- thank you VERY MUCH for the peg-board RT curves. It is the only data I could readily find, and it answered my question semi-satisfactorily.
First your questions....
> 20% perforated hardboard....is basically 1" center pegboard with 1/4" holes.
1/4" on 1" pegboard is 5% open. (One hole per square inch. Hole is 1/4", which by pie-are-square is 0.125"^2*3.14 or 0.04908 square inches of hole per square inch of surface.)
> So the goal is to have it as even as possible through the entire frequency range.
For un-assisted speech, the goal is 1.6 seconds in the 500Hz-2KHz range. This is for lecture halls which are larger than typical domestic spaces. Any drier, the talker strains to get good sound level. Any wetter, vowels mask consonants and intelligibility suffers. Nobody designs for that today: even small halls get PA systems so we don't need reverb to assist the talker. Larger halls "can" be tamed with directional speakers (but often aren't).
Music is glorified speech. We should also account for balance over many octaves. For music *performance*, the goal is usually 1.2 to 1.7 seconds in midrange and (as Pano showed) 1.1 to 2 times that in deep bass. This has varied over history, with musical taste but also with construction materials. Because any acoustician who has worked enough to know his stuff *knows* that you can not argue with basic material selection (just as Pano did drywall... today any other choice is difficult for residential work). So acousticians usually go with what is in there. Any major change would double the room's cost. (If Pano paid himself for panel design and build time, it might be near what he paid his sheetrockers.)
In domestic rooms for serious hi-fi, we do not need high RT to assist the speakers in getting acceptable listening level (though very-dry could be a drag).
In many recordings the bass/mid reverb balance is "already in there". Producer selected the room and any added reverb to get the intended effect. So a first choice would be "flat all over".
if you trust the producer, what you really want is the same as his Mastering Room. These are usually uniformly dry all over, but also the listening spot is usually semi-near-field so reverb has minor effect. (But also he is listening for flaws while you are listening for magic.)
ra7> Here's the T30 response in my room.
The wobble from 0.4 to 0.6 is "nothing". (RT has only marginal effect on frequency response.) The dip to 0.25 at 100Hz sucks important bass. My guess is that this is drywall on studs(?). Pound on the wall, does it boom 100Hz? There's no easy fix for this. A second thickness of drywall would shift it down to 70Hz which is still important bass. Four layers would shift to half, 50Hz, which is perhaps more important since speakers are working hard down there. Heavy stuffing *might* reduce the resonant suck-out, but not much, and is hard to do after the fact. While open: Doubling the studs shifts the resonance up to 140Hz, still not a happy point. Spacing studs randomly 8" 16" 24" might spread the suck-out but drives the drywallers crazy and leaves weak spans, easily damaged. What would work is 8" solid concrete, strapping, and then drywall; again this is not usually practical in domestic work.
Aside from some carpet and thin panels to suck-down mids/highs a bit, I think what you do is have plenty of 100Hz in the system (speaker selection or EQ).
ANYWAY.....
My "music" is a Diesel tractor with enclosed cab. It gets deafening in there. Half heavy steel sheet, half heavy glass. Few good places for sound absorption: floor is a mess of pedals, seats, and braces, walls are 2/3 windows.
However the ceiling is clear and is a large fraction of the total surface area. Raw fiberglass would be no good, but I hit on pegboard over fuzz and happened to have a free sheet of peg. But will 5% open absorb enough?
Pano's data says "it will help". Although just 5% open, mid-size sound waves see 95% of the area as 99% hard, but 5% of the area as 99% open. The mid-size waves "funnel" into the holes.
Shorter waves (high frequencies) don't have time to move over an inch, so Pano's data shows absorption fading above 4KHz.
Long waves (bass) go into the holes fine but then... what? You can't absorb a big wave with a small space. A tenth-wavelength deep space is "hard". Pano's several inches is good to 300Hz (45" wavelength) but does little for lower frequencies. (There may be a dip below 90Hz which may be pegboard resonant suck-out).
My "room" is smaller than Pano's. Say 4'x5'x6' (at least it is not a cube!). At 6' tall I can not spare many inches off the ceiling. In fact I have 3/4" stiffeners. That gives a 1.8KHz lower limit. Takes the clatter off the racket. I'll want to add bulk absorption (bagged batts) in every stray corner.
Pano -- thank you VERY MUCH for the peg-board RT curves. It is the only data I could readily find, and it answered my question semi-satisfactorily.
First your questions....
> 20% perforated hardboard....is basically 1" center pegboard with 1/4" holes.
1/4" on 1" pegboard is 5% open. (One hole per square inch. Hole is 1/4", which by pie-are-square is 0.125"^2*3.14 or 0.04908 square inches of hole per square inch of surface.)
> So the goal is to have it as even as possible through the entire frequency range.
For un-assisted speech, the goal is 1.6 seconds in the 500Hz-2KHz range. This is for lecture halls which are larger than typical domestic spaces. Any drier, the talker strains to get good sound level. Any wetter, vowels mask consonants and intelligibility suffers. Nobody designs for that today: even small halls get PA systems so we don't need reverb to assist the talker. Larger halls "can" be tamed with directional speakers (but often aren't).
Music is glorified speech. We should also account for balance over many octaves. For music *performance*, the goal is usually 1.2 to 1.7 seconds in midrange and (as Pano showed) 1.1 to 2 times that in deep bass. This has varied over history, with musical taste but also with construction materials. Because any acoustician who has worked enough to know his stuff *knows* that you can not argue with basic material selection (just as Pano did drywall... today any other choice is difficult for residential work). So acousticians usually go with what is in there. Any major change would double the room's cost. (If Pano paid himself for panel design and build time, it might be near what he paid his sheetrockers.)
In domestic rooms for serious hi-fi, we do not need high RT to assist the speakers in getting acceptable listening level (though very-dry could be a drag).
In many recordings the bass/mid reverb balance is "already in there". Producer selected the room and any added reverb to get the intended effect. So a first choice would be "flat all over".
if you trust the producer, what you really want is the same as his Mastering Room. These are usually uniformly dry all over, but also the listening spot is usually semi-near-field so reverb has minor effect. (But also he is listening for flaws while you are listening for magic.)
ra7> Here's the T30 response in my room.
The wobble from 0.4 to 0.6 is "nothing". (RT has only marginal effect on frequency response.) The dip to 0.25 at 100Hz sucks important bass. My guess is that this is drywall on studs(?). Pound on the wall, does it boom 100Hz? There's no easy fix for this. A second thickness of drywall would shift it down to 70Hz which is still important bass. Four layers would shift to half, 50Hz, which is perhaps more important since speakers are working hard down there. Heavy stuffing *might* reduce the resonant suck-out, but not much, and is hard to do after the fact. While open: Doubling the studs shifts the resonance up to 140Hz, still not a happy point. Spacing studs randomly 8" 16" 24" might spread the suck-out but drives the drywallers crazy and leaves weak spans, easily damaged. What would work is 8" solid concrete, strapping, and then drywall; again this is not usually practical in domestic work.
Aside from some carpet and thin panels to suck-down mids/highs a bit, I think what you do is have plenty of 100Hz in the system (speaker selection or EQ).
ANYWAY.....
My "music" is a Diesel tractor with enclosed cab. It gets deafening in there. Half heavy steel sheet, half heavy glass. Few good places for sound absorption: floor is a mess of pedals, seats, and braces, walls are 2/3 windows.
However the ceiling is clear and is a large fraction of the total surface area. Raw fiberglass would be no good, but I hit on pegboard over fuzz and happened to have a free sheet of peg. But will 5% open absorb enough?
Pano's data says "it will help". Although just 5% open, mid-size sound waves see 95% of the area as 99% hard, but 5% of the area as 99% open. The mid-size waves "funnel" into the holes.
Shorter waves (high frequencies) don't have time to move over an inch, so Pano's data shows absorption fading above 4KHz.
Long waves (bass) go into the holes fine but then... what? You can't absorb a big wave with a small space. A tenth-wavelength deep space is "hard". Pano's several inches is good to 300Hz (45" wavelength) but does little for lower frequencies. (There may be a dip below 90Hz which may be pegboard resonant suck-out).
My "room" is smaller than Pano's. Say 4'x5'x6' (at least it is not a cube!). At 6' tall I can not spare many inches off the ceiling. In fact I have 3/4" stiffeners. That gives a 1.8KHz lower limit. Takes the clatter off the racket. I'll want to add bulk absorption (bagged batts) in every stray corner.
Hmmm.... hard to say, Bill. They certainly worked well to kill the "Ping" echo that is so common in gypsum board rooms. I created an acoustic nightmare by putting up drywall.
Would a diffuser have worked as well or better? Probably, as the nasty ping usually lives right in the midrange. Wavelengths of around 12-15 inches (30-40 cm). Nice thing about diffusers is that you don't lose the energy, just randomize it.
Would a diffuser have worked as well or better? Probably, as the nasty ping usually lives right in the midrange. Wavelengths of around 12-15 inches (30-40 cm). Nice thing about diffusers is that you don't lose the energy, just randomize it.
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