Yes, I did the tests.... the lp turned out to be 2 db more than the hp section. I will post my measurements soon. My laptop went down with some rogueware... and I've been trying to clean up the mess (why do people spend time doing this nonsense when they can be doing something productive?)
The frequency response already showed that, so I knew it would be louder. Anyway, I still think it is well balanced, especially considering the full range driver (its a two way with woofer up to 130 Hz, crossed to a full range driver above) falls off the chart after 15 khz.
The frequency response already showed that, so I knew it would be louder. Anyway, I still think it is well balanced, especially considering the full range driver (its a two way with woofer up to 130 Hz, crossed to a full range driver above) falls off the chart after 15 khz.
Cool!
If the +2dB sounds right, keep it. Your ears (and your tastes) may differ from the measurement mic.
Sorry to hear about your laptop. Sounds like a pain.
If the +2dB sounds right, keep it. Your ears (and your tastes) may differ from the measurement mic.
Sorry to hear about your laptop. Sounds like a pain.
In one word "Money" people actualy make money creating that crap.Boy would I like to meet some of them.I spent a month and a half last summer trying to clean up my computer.Had a real nasty bugger and it kept downloading new trojans,you delete one and there would be 5 more.Finally I just reformatted my hard drives,and since got external drives with back-up software.And don't click on anything that I can't scan first with Anti-virus.Also McAfee site advisor works well for me.Good Luck with that.
Kind Regards !!!
What about room measurements? SUM touched on this earlier in the thread that the room was on his top five important measurements. So what are the important things to measure in a room. I always do the FR from 5 positions across my couch, and now I do 10. I look at the RT60 and can see it change as I add room treatments. Dr. Toole says it's not very important and if I remember correctly that's because it's low enough in most room that you can typically play any music in your room. FR is most important in the modal region typically below 200Hz. What else is there to look at?
Here's my most recent room measurements:
So what else do I need to look at to determine the performance of my room?
Thanks,
Dan
Here's my most recent room measurements:
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So what else do I need to look at to determine the performance of my room?
Thanks,
Dan
Room response is very interesting. Like noise, once it get's below a certain value, the system performance is dominant. I would still look at CSD and tone bursts. In the listening session during investagation of cable effects on input impedance, it was discovered that as we gradually turn the volume up, the first thing that starts to become more audible is the stored energy in the system, then, depending on which occurs first, amp clipping effects or room reflection/room modes.
Probably a good thing to do let the room modes assist where the low end of speakers roll off.
Probably a good thing to do let the room modes assist where the low end of speakers roll off.
Some of the FR bump-ups are uniform as you measure across the couch (30, 150 Hz) and some have variability. That might mean they are modes at right angles to the couch. So that may offer some clues to re-doing room furnishings.
Toole suggests using parametric eq to control the room mode bump-ups but not to fuss so much with the cuts. That has been my experience, using two bass eq modules - very helpful.
For those lurking in this thread without high tech gear or who have thrown up their hands in frustration over using mics (me) or who buy organically grown spinach, my trusty 50 year old PopSci test record with a 300-30 glide tone (with cricket markers at 50 Hz intervals) is comparable in helpfulness to the 10-mic measurement.
Toole suggests using parametric eq to control the room mode bump-ups but not to fuss so much with the cuts. That has been my experience, using two bass eq modules - very helpful.
For those lurking in this thread without high tech gear or who have thrown up their hands in frustration over using mics (me) or who buy organically grown spinach, my trusty 50 year old PopSci test record with a 300-30 glide tone (with cricket markers at 50 Hz intervals) is comparable in helpfulness to the 10-mic measurement.
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Hi,
I think determining the delay and frequency response of the early room reflections is important.
Here I made some wavelet measurements:
http://www.diyaudio.com/forums/multi-way/121385-loudspeakers-room-system-30.html#post2275786
- Elias
I think determining the delay and frequency response of the early room reflections is important.
Here I made some wavelet measurements:
http://www.diyaudio.com/forums/multi-way/121385-loudspeakers-room-system-30.html#post2275786
- Elias
There are CDs out - notably by Stereophile - that have sweeps and glides. But no markers! Very frustrating. Ditto some software generators.
Ben's idea is a good one. Look at the ~100Hz response. That's where there is the biggest variation from place to place. Why? Then maybe the area around 60Hz. Also, that hump centered on 600Hz would bother me, but it might add something that you like to the system sound.
Otherwise, it's looking pretty good.
As long as you know the sweep rate, you can use a virtual or real chart recorder with the test disc tones.
Side question, do people believe that speakers should be designed to avoid or minimize the Allison effect or even simple floor dips that accompany any in-room measurement?
Side question, do people believe that speakers should be designed to avoid or minimize the Allison effect or even simple floor dips that accompany any in-room measurement?
Ben, I really like your assessment! Unfortunately the furniture placement is not subject to negotiation. So treatment is in order. My bet would be that the 30Hz issue has to do with the long dimension of the room where the 140Hz issue has to do with the height. My question would be that if a made a large bass absorber to go across the back of the couch and another to hang from the ceiling above the couch would that then solve the problem? How does one know where to treat?
Elias, I like that thought as well.
Believe it or not Pano, I can't hear the approx. 500Hz bump or the 1500Hz even during the sweep. It's been there no matter what speakers are in the room, but these speaker do have a bump near there. The one that's audible is the 140Hz. Even it isn't radical, just slightly audible. The speaker's response looks like this in 11.25 degree steps:
Dan
Elias, I like that thought as well.
Believe it or not Pano, I can't hear the approx. 500Hz bump or the 1500Hz even during the sweep. It's been there no matter what speakers are in the room, but these speaker do have a bump near there. The one that's audible is the 140Hz. Even it isn't radical, just slightly audible. The speaker's response looks like this in 11.25 degree steps:
Dan
Never fearing to offer advice when I don't know what I'm talking about....
I suspect there isn't much solid information on treating small rooms, which Toole repeatedly calls different than concert halls. Moreover, truly hard to influence low tones, and Toole repeatedly cautions against believing manufacturer's fluff particularly about sound absorbers.
The traditional view is that any absorption anywhere in the room is helpful additively, but then Toole goes into detail about pressure highs and lows in specific places for specific modes.
Bass is absorbed by depth. You need to get like 6 inches deep to start eating up sound below maybe 80 Hz, but then lots of materials (or air) can be in that depth.
I once had a wonderful large music room with a beamed ceiling. In a major refurb, instead of drywall, we used Tectum on some walls, one of the few truly effective low frequency absorbers, which looks like shredded wheat panels and likely you've seen it around. With some heavy-weight "acoustic" fiberglass in the stud space behind, it seemed to give the room a nice sound character.
Maybe I'm a klutz, but I never have success hitting the mark with "tuned" things, even if the name Helmholtz is on the theory. You could try esp. if you design the absorber for ease of re-tuning.
Motorcycle mufflers are about the hardest challenge to absorbtion I know. I used a very heavy ceramic foam-like sheeting made for furnaces.
Spouting half-wrong information isn't so bad if it stimulates better informed people to come forward with better information.
All true Ben. My bass traps are 6 inches and 18 inches deep with an air gap behind them, but they obviously still aren't enough. One is 8ft tall and the other is 4ft. Both are 2ft wide. Dr. Toole says something to the effect of absorption needing to be 1/4 wavelength of the offending frequency away from the wall to be maximally effective (where particle velocity is highest) and vibrating diaphragmatic absorbers should be placed at the borders where pressure is at a maximum. So far what I've done supports Dr. Toole's assertions--I've got a ton of graphs. Seems most people who have made Helmholtz cylindrical resonators seem to place them in the corners. I'd like to not have to buy an EQ, so I'm going to try and make the 140Hz bump disappear if it's possible.
AVG:
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After:
Look at the rt60.
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Dan
AVG:
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Look at the rt60.
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Dan
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Ah, dantheman, the trouble is you are too nice a fellow.
Remember, Toole is careful to distinguish when he is aiming for group happiness and when he is aiming for sweet-spot happiness. Now if you were selfish, like me, you could tune the one spot on the couch where you sit. THAT could be done with EQ! Getting the whole couch, kids seats, and baby's crib right requires getting the room right.
Or using a bunch of woofers - which is where I am exploring these days. Purists would be aghast, but a bunch of different woofers located haphazardly with varying resonances makes a nice system and not at all bad with my giant virgin-pure dipole 110-3200 Hz ESL mid-range. (My apologies to the folks trying to build that One Great TH sub-woofer for their music room.)
I used to have occasional access to a really large anechoic chamber - not like the cheapy one Harman Cosmic Corp uses. The scary thing is walking around on the bouncy trampoline wire floor while looking down deep into the fiberglass wedges below and everywhere... 4 feet deep or maybe more. Scary. Kids, don't try that at home.
Remember, Toole is careful to distinguish when he is aiming for group happiness and when he is aiming for sweet-spot happiness. Now if you were selfish, like me, you could tune the one spot on the couch where you sit. THAT could be done with EQ! Getting the whole couch, kids seats, and baby's crib right requires getting the room right.
Or using a bunch of woofers - which is where I am exploring these days. Purists would be aghast, but a bunch of different woofers located haphazardly with varying resonances makes a nice system and not at all bad with my giant virgin-pure dipole 110-3200 Hz ESL mid-range. (My apologies to the folks trying to build that One Great TH sub-woofer for their music room.)
I used to have occasional access to a really large anechoic chamber - not like the cheapy one Harman Cosmic Corp uses. The scary thing is walking around on the bouncy trampoline wire floor while looking down deep into the fiberglass wedges below and everywhere... 4 feet deep or maybe more. Scary. Kids, don't try that at home.
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I think you need to be careful with the idea that EQ, especially above 1khz is even making a single sweet spot. I won't disagree as long as you can show through a series of averaged measurements within the actual head listening window that the response is good. However, its often the case that people measure within a 6" window, or worse yet, a single point roughly where the middle of their head is, and assume that eqing it flat there will mean its flat 6"s to the left or right. I've not found that to be the case. Then add in the effect that Eqing for a single point can have on the off-axis response. Since those are reflecting back and becoming a part of what we hear, and as Dr. Toole points out, we want this in a small room, absorbing first reflections at the sidewall can be a bad thing, I think the off-axis is important to look at.
I like to keep my EQ to less than 200hz or so, and even then, I like to use very little, and have it be right over a very broad range if possible. I live alone right now, and have a setup that is very much a selfish setup, but even I have been finding that trying to create a single sweet spot isn't easily done with EQ. I have numerous measurements taken not just at different listening positions, but different area's within the single point listening window that shows fairly substantial variations in the bass. I'm sure its the room, but it doesn't chance the fact that they are there and real.
As for bass traps, tuned traps are, in my opinion, the only option for adding lf dampening to a room. You don't have to hit the market precisely if you design them right, and changing the tuning isn't really a big deal either. Just lower the Q and broaded the response. Then use enough of them to have a big enough effect and you will find them very effective. I find the resonant panel type to be best, and I basically try to use a CLD panel made of sandwhiched gypsum board hooked into an 8" deep panel. I use software to do the calculations for me, and use acoustic insulation in the cavity to lower the Q. Using an accelerometer I have found the bass resonance point to be close enough to the mark, and with the low Q broad response, it works well at adding LF dampening. I had 2 of these in my last place but couldn't easily take them with me when I move. I plan to make this another project for my new room, as its something I'm badly in need of.
I think you will find that velocity absorbers simply can't be made big enough to have any appreciable effect below 80hz, and even at 140hz they just don't do much. I've made them as big as 12" thick of acoustic material with a total size of 5'x4' by two panels, with a 6" air pocket behind, and still could not measure any worthwhile improvements. Add to that the completely unrealistic size of these panels (who wants to give up 18" of their wall space like that), and I rather quickly scrapped the idea. As far as I'm concerned, those are as ridiculous as it gets, if they didn't work, nothing I would want would work, they didn't work enough, so I went to other routes.
I like to keep my EQ to less than 200hz or so, and even then, I like to use very little, and have it be right over a very broad range if possible. I live alone right now, and have a setup that is very much a selfish setup, but even I have been finding that trying to create a single sweet spot isn't easily done with EQ. I have numerous measurements taken not just at different listening positions, but different area's within the single point listening window that shows fairly substantial variations in the bass. I'm sure its the room, but it doesn't chance the fact that they are there and real.
As for bass traps, tuned traps are, in my opinion, the only option for adding lf dampening to a room. You don't have to hit the market precisely if you design them right, and changing the tuning isn't really a big deal either. Just lower the Q and broaded the response. Then use enough of them to have a big enough effect and you will find them very effective. I find the resonant panel type to be best, and I basically try to use a CLD panel made of sandwhiched gypsum board hooked into an 8" deep panel. I use software to do the calculations for me, and use acoustic insulation in the cavity to lower the Q. Using an accelerometer I have found the bass resonance point to be close enough to the mark, and with the low Q broad response, it works well at adding LF dampening. I had 2 of these in my last place but couldn't easily take them with me when I move. I plan to make this another project for my new room, as its something I'm badly in need of.
I think you will find that velocity absorbers simply can't be made big enough to have any appreciable effect below 80hz, and even at 140hz they just don't do much. I've made them as big as 12" thick of acoustic material with a total size of 5'x4' by two panels, with a 6" air pocket behind, and still could not measure any worthwhile improvements. Add to that the completely unrealistic size of these panels (who wants to give up 18" of their wall space like that), and I rather quickly scrapped the idea. As far as I'm concerned, those are as ridiculous as it gets, if they didn't work, nothing I would want would work, they didn't work enough, so I went to other routes.
Very interesting post. Thanks.
Dunno about comparing a 5x4 panel (20 sq ft) to a complete wall 9.5x15 (142 sq ft) of Tectum. Tectum is pretty cheap stuff and considering it needs no finishing, anybody with a screwdriver and do it, and for professionals also cheap to install. Tectum Inc. claim an absorption index at 125 Hz is .42, which is not shoddy at all. Made from Wisconsin Aspen (I guess they couldn't find those magic Baltic Birch trees). When you go built-in by replacing drywall or tired old plaster on lath (which is a nice material acoustically), assuming you own the home, there may be no loss of living space.
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no I agree, that is something very different. Tectum has some mass to it as well, it may have multiple factors helping it along.
Still, my point was that adding bass absorption to a room, which normally means adding traps to an existing room, isn't very effective when it relies on velocity absorbers. Thats my experience, lots of people disagree. I just happen to have a Dr. Toole who agrees with me.
Thick velocity absorbers can be useful, I just wouldn't suggest expecting them to fix those 30-80hz bass problems. Some of my biggest problems are in that range, especially in the 50-80hz range, and I find bass traps I can hang on a wall to not be very effective. Tectum encompassing an entire wall is a little different of course.
Still, my point was that adding bass absorption to a room, which normally means adding traps to an existing room, isn't very effective when it relies on velocity absorbers. Thats my experience, lots of people disagree. I just happen to have a Dr. Toole who agrees with me.
Thick velocity absorbers can be useful, I just wouldn't suggest expecting them to fix those 30-80hz bass problems. Some of my biggest problems are in that range, especially in the 50-80hz range, and I find bass traps I can hang on a wall to not be very effective. Tectum encompassing an entire wall is a little different of course.
Low Frequency Sound Absorber
This stuff claims .97 at 125hz, I bought a box to give it a shot. I made a few panels that were 8" thick, and of all the velocity absorbers I've ever made, these were the most effective, still not great. Like I said, I'm just not a big fan of giving up tons of wall space, and these were taking up a foot of wall depth in my room. When I can get considerably more LF dampening in that same range using other methods, and give up only 6" of wall space, why not.
I have a design that I've not tried yet, but I suspect will be effective based on simulations. It's a hybrid slat bass absorber that I would likely make using solid maple or birch. Could be really pretty, easy to make, and hopefully quite effective. Basically just a 5" thick frame with a solid back, 4" of absorption material, like that BAP if you want to spend the big bucks, or rock wool if you want to spend a bit less, and then a bunch of evenly spaced slats. They need to be a very precise spacing and depth, but basically gives you helmholts resonance and velocity absorption in one. The slats also would offer scattering at higher frequencies.
This stuff claims .97 at 125hz, I bought a box to give it a shot. I made a few panels that were 8" thick, and of all the velocity absorbers I've ever made, these were the most effective, still not great. Like I said, I'm just not a big fan of giving up tons of wall space, and these were taking up a foot of wall depth in my room. When I can get considerably more LF dampening in that same range using other methods, and give up only 6" of wall space, why not.
I have a design that I've not tried yet, but I suspect will be effective based on simulations. It's a hybrid slat bass absorber that I would likely make using solid maple or birch. Could be really pretty, easy to make, and hopefully quite effective. Basically just a 5" thick frame with a solid back, 4" of absorption material, like that BAP if you want to spend the big bucks, or rock wool if you want to spend a bit less, and then a bunch of evenly spaced slats. They need to be a very precise spacing and depth, but basically gives you helmholts resonance and velocity absorption in one. The slats also would offer scattering at higher frequencies.
This is a good site for absorption coefficients of about every material imaginable--well, that's a stretch: http://www.bobgolds.com/AbsorptionCoefficients.htm
Pjpoes, my experience has mirrored yours. It takes a ton of bass absorption to get a small measurable effect. Where does one get a good cheap accelerometer and how did you calculate your panel? I've gotten a far larger effect from crossover frequency and phase adjustments combined with placement techniques than I have from bass absorption.
Ben you are correct about my desires, but maybe less correct about my motivation.
This room will double as a home studio and I also don't want to be restricted to and one spot. It would be nice to share with fruit of my labor with others, but for some reason I doubt they will be as pleased as I would be with great results. I realize that perfection will require some EQ in the end regardless unless I figure out something much better than what I've been doing. I do have 2 subs, but I bet more would be better.
Right now I'm just pondering how to make the bass better. Suggestions welcome.
Dan
Pjpoes, my experience has mirrored yours. It takes a ton of bass absorption to get a small measurable effect. Where does one get a good cheap accelerometer and how did you calculate your panel? I've gotten a far larger effect from crossover frequency and phase adjustments combined with placement techniques than I have from bass absorption.
Ben you are correct about my desires, but maybe less correct about my motivation.
This room will double as a home studio and I also don't want to be restricted to and one spot. It would be nice to share with fruit of my labor with others, but for some reason I doubt they will be as pleased as I would be with great results. I realize that perfection will require some EQ in the end regardless unless I figure out something much better than what I've been doing. I do have 2 subs, but I bet more would be better. Right now I'm just pondering how to make the bass better. Suggestions welcome.
Dan
Been working on the 2 subs placement, phase, and filter and I am using the Mackie HR624mkII now and thus the graph titles.
Still have a couple more things I'd like to try. I sure wish there was a better way to know how to place and set your subs. This took forever just to get here.
Sounds good though--easily my best. See my previous post and compare to my last best. "The last of the best. They call me a gris gris man." Dr. John
Dan
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Still have a couple more things I'd like to try. I sure wish there was a better way to know how to place and set your subs. This took forever just to get here.
Sounds good though--easily my best. See my previous post and compare to my last best. "The last of the best. They call me a gris gris man." Dr. John
Dan
Saw Dr. John a few months back. Not what he used to be.
Great looking response. When doing room curves and averaging, some frequency averaging is a "must". 1/3 oct is probably best. Gated measurements can get away with much narrower bandwiths, but room measurements with refelctions need a fairly wide spectral average to yield stable data. Your multipple curve plot is very telling about the huge variance of data at only a few positions.
Great looking response. When doing room curves and averaging, some frequency averaging is a "must". 1/3 oct is probably best. Gated measurements can get away with much narrower bandwiths, but room measurements with refelctions need a fairly wide spectral average to yield stable data. Your multipple curve plot is very telling about the huge variance of data at only a few positions.
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