At what point did you stop REW measuring and buy treatments?

billrobbo

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Although, If you plug in the length as 30', to take into account the rear wall behind the couch it does make it a little worse.

39100
 

linearphase

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Wow! Well with those room dimensions, and the low ceiling I am at a loss as to recommend anything to do. The ceiling is really too low to add much absorption, and the differing wall construction will have an audible impact on imaging because it alters Low frequency absorption significantly. About the only thing you could do, if desired, is to add some low frequency bass traps to the room extension at the back right of the room. Looks like there is lot of area there. The room is complicated enough that no software I have will simulate it so if you choose to add bass traps you would simply put them in the areas with the highest measured pressure ( SPL) AT the frequencies where the peaks AND dips are the greatest. That requires that you simply measure sweeps every foot or so in any area where traps are acceptable. Traps uniquely have the ability to minimize both peaks and dips. one that are effect are at least 1 ft square but bigger is better. Floor to ceiling corner traps are likely to work the best in your room.

So my suggestions if you wish to improve the sound further:

1a. Move the mains out to 36" from the front wall, leave the distance from the side wall alone for now. Remeasure (one speaker at a time) at the centered MLP with the speakers moved 6" at a time from 36" to 60". Choose the curve that is the smoothest down the crossover frequency which looks like it should be 80Hz. I would also listen with the speakers at the two positions that look the most promising. Do not concern yourself with frequencies below 80 as those will be reproduced by the subs anyway.

1b. If this is too much work have someone who's voice is very familiar stand at those positions and while taking slowly move forward. Mark the position the floor when the voice sounds the most lifelike. If you wish you can repeat this process 6" closer and then farther to the sidewall. Repeat for the other side due to the room acoustic asymmetry. Once you have establish the best regions determine speaker positions that are both in these regions AND symmetrical with respect to he room. This is quicker and likely will produce better results.

2. Generally toe in the speakers so they point directly at the centered LP. You can also repeat either of the above procedures moving the MLP forward and back a few inches at time.

3. Tweak the toe in and MLP to produce the best sound and most lifelike imaging. Keep things very symmetrical. if you have access to pink noise you can also play it over both speaker to confirm a good centered image. Then reverse the leads on ONE speaker. You should hear a "hole" between the speakers with the rest of the sound speed evenly out from there, ideally extending even bit outside the speakers. Tweak the toe in while at the listening position slightly. You should find one position were the noise sounds smooth AND the image just locks to a hole in the center. Don't forget to return the leads back to normal polarity when done here.

DO not proceed until you are satisfied you have optimized this to you satisfaction.

4. Now you can add the sub(s). The are many articles written about sub placement and tuning. I will not repeat those here. My simplified general procedure is:
a. Measure and move the subs (WITHOUT THE MAINS) individually around the room so their response is as flat possible up to 100 Hz or so at the MLP. Then make slight tweaks to their positions so the COMBINED response, measured with both playing, minimizes any major dips. Note that while the subs do NOT have to be symmetrical WRT to MLP it will simplify the setup.
Lacking symmetry you will have to adjust the delay of one sub or the other in 1mS or finer steps to determine the best setting. This only works if your DSP supports separate delays for each sub. I prefer to do this delay adjust by inverting the polarity of one sub and adjusting for the DEEPEST null and then restoring that sub to normal polarity. This is easier than looking for the flattest response because it will likely never be perfectly flat.
b. EQ each sub individually so you remove 1/2 of each major peak ( 20-80Hz). so for example if the response shows a 6 dB peak create a filter that drops that level 3dB. I would not try to boost any dip that is more than 6dB. You can use the REW written instructions, You tube and this forum for help in properly calculating what the best EQ filters are.
c. The last and possibly the hardest to get do is to integrate the subs and mains. This involves:
I.Selecting crossover frequencies and slopes.
II.Tweaking the sub to main delays
III. Adjusting the sub to main level match for the desired frequency response.

I will leave the details for later when I am more awake.
 
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hilde45

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Thank you billrobbo. I've not seen this calculator before. Appreciated.
 

hilde45

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linearphase -- so much good thought in your comments. Thank you.
I’ll make a few remarks in reply.
Part of the low ceiling has been helped by sitting lower and having speakers on 20” stands. But you’re right. They’re an issue. This is what I have right now. Bass traps are definitely on my radar.
1a. I have moved the mains anywhere from flush against the front wall to 7 feet from the front wall, in 2” increments. The LP was also moved in a gazillion combinations with the mains. What I posted here are the absolute best mains/LP position, as judged by hundreds of REW scans. Subs invariably make it worse. Tried lots of combinations of gain, crossover, placement, and phase.
1b. I’ve done this and have also, in conjunction with 1a, done many positions with speakers on the L/R axis.
2. Toe in helps with listening sometimes, but I’m avoiding toe-in to determine best overall solutions.
3. I’ve not tried the “reverse the leads” trick yet. Very interesting.
4. I will try the measurement of the sub, but (a) I only have one, and (b) I have no DSP.
 

linearphase

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linearphase -- so much good thought in your comments. Thank you.
I’ll make a few remarks in reply.
Part of the low ceiling has been helped by sitting lower and having speakers on 20” stands. But you’re right. They’re an issue. This is what I have right now. Bass traps are definitely on my radar.

Lowering the speakers will help the ceiling bounce but increase the floor bounce. This will also shift the floor bounce frequency up which is not desirable.
Is the ceiling dropped? The ceiling reflection is 60% as strong as the sound arriving from the speaker directly. This is the worst reflection I have ever seen in thousands of measurements. If you do only one thing this is what I would attack, if it is possible at all. If possible perhaps you could insert a large thick absorber in a hole cut in the ceiling and trim it out. this would have be accurately positioned centered at the first refection point on (in) the ceiling. If you need help locating this let me know. As a short term trial you could just tack 6" of fiberglass ( OC703 mentioned below) to that point. Obviously this is not practical from a long term usage standpoint.

Do your research on the bass traps. Look for those that absorb mostly below 250 Hz. You may have to use scatter plates which reduce absorption at higher frequencies and maybe better yet, a limp mass TYPE of construction so high frequencies are not absorbed much at all. You already are on the borderline or having to much HF absorption.
something like this stacked in the (corners floor to ceiling) would work. Choose to add the range limiter option. Probably would need at least two corners treated, 6.5ft high.



If you DIY you can just buy some Owens Corning 703, maybe available locally, and layer it to be at least 6" thick. You can cut the edge to be mitered to match the corner if you like. Then just leave an air gap between the last sheet and the corner if you like. It improves absorption characteristics. Plans to build are on the referenced web site and all over the internet.


1a. I have moved the mains anywhere from flush against the front wall to 7 feet from the front wall, in 2” increments. The LP was also moved in a gazillion combinations with the mains. What I posted here are the absolute best mains/LP position, as judged by hundreds of REW scans. Subs invariably make it worse. Tried lots of combinations of gain, crossover, placement, and phase.

Good job. When you say crossover and phase were tested what do you mean? Since you have done the voice test did you hear clear differences or did it sound mostly the same to you?

1b. I’ve done this and have also, in conjunction with 1a, done many positions with speakers on the L/R axis.
2. Toe in helps with listening sometimes, but I’m avoiding toe-in to determine best overall solutions.

The toe in mostly effects the mid and high frequencies. So not super important during testing. It is very important during listening.

3. I’ve not tried the “reverse the leads” trick yet. Very interesting.

This is called the null technique or differential measurement. It is more sensitive and repeatable because the normal static errors are removed and you can focus on just one factor. It can be adapted to almost every type of measurement.

4. I will try the measurement of the sub, but (a) I only have one, and (b) I have no DSP.

Do you have crossover? Do you stream audio from a computer? Without a proper crossover and some signal processing only part of the process will work. DSP virtually always gives the biggest bang for the buck. Even inexpensive DSP can produce results that produce an overall improvement in sound. It is controversial in some circles but based on real life experience is is a VERY rare system that will not benefit. For those that say it sounds bad I firmly believe either they have ears that or a lot better than mine OR they just have done something wrong. This includes some audio "professionals".

As I said proper sub integration is not trivial. it requires knowledge of acoustics, measurements, and understanding of the technologies employed or a willingness to learn those. A sub will produce excellent results if well done.

Two potential solutions should you decide to pursue this are:
1. Mini DSP 2x4HD optional with DIRAC. Dirac semi automates the process and make EQ easier but does not solve the crossover problem without knowledge on the users part.
2. Mini DSP SHD studio ( uses your own DACs) or SHD ( has high quality integrated DACS).

Both allow flexible crossover, basic EQ and advanced time and frequency correction.

These are not the ultimate weapons. They do not equal the performance of $50,000 stand alone DACS. But unless your ears are perfect and trained, you have a VERY high end system, you have a perfect room with perfect installation I sincerely doubt you would hear any difference. They simply represent cost effective equipment with which I am familiar and can assist.


IF YOU ARE ABLE TO FIND A GOOD PLACE FOR A SUB WE CAN LIKELY IMPROVE THE SOUND OF YOUR SYSTEM. IN YOUR ROOM IT MIGHT BE WISE TO TRY A SUB POSITION NEAR THE LP. THIS IS NOT VERY COMON BUT CAN BE THE BEST OVERALL SOLUTION. I had one guy that had room in which the speakers occupied almost 30% of the total room volume. the room was not very big. A near field sub worked wonders in his room. Your mileage may vary...

See answers above.
 
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hilde45

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Do you have crossover? Do you stream audio from a computer? Without a proper crossover and some signal processing only part of the process will work. DSP virtually always gives the biggest bang for the buck. Even inexpensive DSP can produce results that produce an overall improvement in sound. It is controversial in some circles but based on real life experience is is a VERY rare system that will not benefit. For those that say it sounds bad I firmly believe either they have ears that or a lot better than mine OR they just have done something wrong. This includes some audio "professionals".

As I said proper sub integration is not trivial. it requires knowledge of acoustics, measurements, and understanding of the technologies employed or a willingness to learn those. A sub will price excellent results if well done.

Two potential solutions should you decide to pursue this are:
1. Mini DSP 2x4HD optional with DIRAC. Dirac semi automates the process and make EQ easier but does not solve the crossover problem without knowledge on the users part.
2. Mini DSP SHD studio ( uses your own DACs) or SHD ( has high quality integrated DACS).

Both allow flexible crossover, basic EQ and advanced time and frequency correction.

These are not the ultimate weapons. They do not equal the performance of $50,000 stand alone DACS. But unless your ears are perfect and trained, you have a VERY high end system, you have a perfect room with perfect installation I sincerely doubt you would hear any difference. They simply represent cost effective equipment with which I am familiar and can assist.


IF YOU ARE ABLE TO FIND A GOOD PLACE FOR A SUB WE CAN LIKELY IMPROVE THE SOUND OF YOUR SYSTEM. IN YOUR ROOM IT MIGHT BE WISE TO TRY A SUB POSITION NEAR THE LP. THIS IS NOT VERY COMON BUT CAN BE THE BEST OVERALL SOLUTION. I had one guy that had room in which the speakers occupied almost 30% of the total room volume. the room was not very big. A near field sub worked wonders in his room. Your mileage may vary...

See answers above.
linear phase --

Thanks again for all your hard work thinking about my issues.

I'll keep my replies brief.

I have tried 6" of fiberglass on the floor at the 1st reflection point, but not sure I measured. Will try again. I tried 2" on ceiling in correct spots but didn't see much of a result. Probably too thin.

Will research bass traps. I hear you about limp membranes. Don't want to over-deaden. I've watched videos about DIY corner traps. Seems doable.

"Crossover and phase tested" means I tried setting the sub with different setting on the crossover dial on my REL. I flipped the switch from 0 to 180. Lots of combinations tried. The voice test did not reveal huge differences, but it's been a while.

I stream from a Node 2i. It has some in-built controls but not a lot. I understand that DSP might be helpful but some here have said that it won't help with my nulls. It's another type of experiment and at this point I feel a bit overwhelmed. I am keeping this post as a reference note for when I can go down the DSP path. It's time, not money, that's constraining me.

I will try the sub near the LP, though previous experiments didn't show that helped with the nulls and quickly exaggerated the peaks, down low. Still, I'll give it another go.

END
 

hilde45

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P.S. Linearphase, others -- I decided to do a few scans today focused on the floor first reflection spot. I attach the scans, here.

Using a mirror, I sought out the 1st point of reflection from speaker to LP mic. Hard to find, because my listening couch is just in front of the mic. The laser dot first reflects off the mirror INTO the couch's plus cushion and when it finally clears the couch, it's on the ceiling BEHIND the LP mic. So, I don't know exactly what that means except that my couch is sucking a lot of signal in from that reflection. Still, I put the 703 panels down in various ways, described in the scans, so we'll see how they look to you.
 

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linearphase

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This panels are not having much effect at all. Is the floor covered with carpet normally? Is it concrete? I think the reflection is actually coming off the ceiling and is low frequency so requires thick material to absorb. What is the ceiling made of?
If both are hard materials this will be hard to improve on.

The sub ( rel328?) appears to have no hi pass output to remove the LF info from the mains. This makes things difficult because the two response will combine in a non predictable manner. If also does not relive the mains from producing bass.

Place the sub against the front wall in the middle, centered between the speakers use the high level inputs from left and right speakers as recommended. Make sure they are in phase. Set crossover to 60 Hz phase to normal or 0 degrees. When you have time measure the sub near field with the mic within 1" of the driven cone. We are just trying to get an idea of what the crossover frequency is. The objective is to get the point where it is 3 dB down to coincide with the point the mains are also 3dB down. That point on the mains appears to be about 60 Hz. Since the sub is way behind the mains they should be delayed about 7mS to start, but we have no way to do that without DSP so just run a sweep for the MLP with the L main and sub running. Flip the polarity or phase switch to invert or 180 degrees and repeat. For now we are going to do invert trick so identify which position give the biggest DIP near the crossover frequency. If you know how to use the RTA function and signal generator it is handy next. If not just run multiple sweeps, again with the sub and a single main. Adjust the crossover frequency and level for the deepest DIP in response. This simply ensures the the sub and mains are as close to matched in the crossover region as is possible without more sophisticated techniques. Last flip the phase switch to the opposite position it is in and play music with deep bass. if all is well it should sound pretty good. you will need to tweak the level by ear after careful listening to several bass heavy and familiar tracks. hopefully you can find a position where the sub disappears and all you hear is enhanced deep bass.

I know this sounds complicated and time consuming and the first time it it will be. With practice it should converge quite quickly. Without DSP or other EQ this will not be optimum but it will hopefully sound better.


If you are busy no worries. do what you need to. We can come back to this later.
 

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I just clicked on your Cedar Creek Cinema link and watched the video. ... What a wonderful room and setup! Kudos!
Indeed! And Diana Krall performing 'Temptation' - what a beautiful music choice. I love that track!
 

hilde45

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This panels are not having much effect at all. Is the floor covered with carpet normally? Is it concrete? I think the reflection is actually coming off the ceiling and is low frequency so requires thick material to absorb. What is the ceiling made of?
If both are hard materials this will be hard to improve on.

The sub ( rel328?) appears to have no hi pass output to remove the LF info from the mains. This makes things difficult because the two response will combine in a non predictable manner. If also does not relive the mains from producing bass.

Place the sub against the front wall in the middle, centered between the speakers use the high level inputs from left and right speakers as recommended. Make sure they are in phase. Set crossover to 60 Hz phase to normal or 0 degrees. When you have time measure the sub near field with the mic within 1" of the driven cone. We are just trying to get an idea of what the crossover frequency is. The objective is to get the point where it is 3 dB down to coincide with the point the mains are also 3dB down. That point on the mains appears to be about 60 Hz. Since the sub is way behind the mains they should be delayed about 7mS to start, but we have no way to do that without DSP so just run a sweep for the MLP with the L main and sub running. Flip the polarity or phase switch to invert or 180 degrees and repeat. For now we are going to do invert trick so identify which position give the biggest DIP near the crossover frequency. If you know how to use the RTA function and signal generator it is handy next. If not just run multiple sweeps, again with the sub and a single main. Adjust the crossover frequency and level for the deepest DIP in response. This simply ensures the the sub and mains are as close to matched in the crossover region as is possible without more sophisticated techniques. Last flip the phase switch to the opposite position it is in and play music with deep bass. if all is well it should sound pretty good. you will need to tweak the level by ear after careful listening to several bass heavy and familiar tracks. hopefully you can find a position where the sub disappears and all you hear is enhanced deep bass.

I know this sounds complicated and time consuming and the first time it it will be. With practice it should converge quite quickly. Without DSP or other EQ this will not be optimum but it will hopefully sound better.


If you are busy no worries. do what you need to. We can come back to this later.
Thank you, linearphase.

I've copied your experiment into a separate document and separated each stage. I'll try to do the experiment later today or tomorrow and will post results.

I'll answer a couple questions you asked with an attached photo. Basically, a concrete floor with thin carpet. Ceiling is drywall.
 

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AJ Soundfield

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I'm attaching an image of what seems like my best data -- SPL, Waterfall, Spectrogram.
I'm also attaching what wound up on my short list for listening -- in other words, the scans which (to my eye) seemed best and worth examining via critical listening.

I'll answer a couple questions you asked with an attached photo. Basically, a concrete floor with thin carpet. Ceiling is drywall.
I don't see anything wrong with your measurements at all. It would have been nice if they extended a bit higher than 340hz. However, if 82db +/- average between 240-360hz is your average sound level, then essentially, you have predictable (and innocuous) monopole box stand speaker dip in the expected 210hz range, a bit of front wall cancellation at 140hz and a small, 3db ish peak at 80hz.
By far, your best money spent would be to buy/read Floyd Tooles book about how what you have measured there, despite looking scary to a single pressure mic/your eyes, is perceived quite differently by 2 ears and a brain...aka, a living binaural hearing system. I don't see anything there that can't be "fixed" by a couple subwoofers, namely the issue of the bass falling off below 80hz. The peak at 25hz could be noise, possibly HVAC.
How does it sound? That is the only thing that should really matter.

cheers
 

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I don't see anything wrong with your measurements at all. It would have been nice if they extended a bit higher than 340hz. However, if 82db +/- average between 240-360hz is your average sound level, then essentially, you have predictable (and innocuous) monopole box stand speaker dip in the expected 210hz range, a bit of front wall cancellation at 140hz and a small, 3db ish peak at 80hz.
By far, your best money spent would be to buy/read Floyd Tooles book about how what you have measured there, despite looking scary to a single pressure mic/your eyes, is perceived quite differently by 2 ears and a brain...aka, a living binaural hearing system. I don't see anything there that can't be "fixed" by a couple subwoofers, namely the issue of the bass falling off below 80hz. The peak at 25hz could be noise, possibly HVAC.
How does it sound? That is the only thing that should really matter.

cheers
Thank you, AJ, that's a really grounded thing to hear. I want to assure you that I'm not OCD chasing better graphs. The system sounds really lovely. The reason I'm pursuing this now is that I have heard from others that a bit of treatment can bring a good room to a great level, and until I hear what that sounds like, I will wonder how much better it can sound. (It's like the first time you taste, say, really good steak. In a moment, what you've been missing is apparent and you're glad you've elevated your palate and imagination.)

I will check out that book (heard of it many times) and consider the subwoofer "fix," but I assure you I am not Ahab and this null is not Moby Dick! Just want to give it a good try before packing in the towel. Also, I've learned a lot by pursuing this question, and have enjoyed it, too. It puts me in contact with smart and helpful people -- such as yourself!
 

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The system sounds really lovely.
Great. Since you band limited measurements to "bass", I had presumed this was the specific area of your concern. If you are satisfied there, better yet. Based on your measurement, what I saw, would probably not satisfy my own needs for extension, power, etc. YMMV.
It might be helpful to do a sweep without the system playing, to see the baseline ambient/baseline level, especially at lower frequency (<50 hz or so).

The reason I'm pursuing this now is that I have heard from others that a bit of treatment can bring a good room to a great level, and until I hear what that sounds like, I will wonder how much better it can sound. (It's like the first time you taste, say, really good steak. In a moment, what you've been missing is apparent and you're glad you've elevated your palate and imagination.)
People on audio forums say/believe a lot of things, mostly sincere. That doesn't necessarily make them so, or at best, anecdotal subjective opinions. Tooles book is the exact opposite, citing controlled listening tests extensively (most not done by him, but internationally, by a wide range of researchers), what "ears" actually hear, rather than believe/have read somewhere. There have been some tests of the so called "treatments" you wish for, often with very amusing results.

I will check out that book (heard of it many times) and consider the subwoofer "fix,"
Cool and as I mentioned, if the depth, extension, etc are already to your (2 ch) needs, then no sub "fix' would be needed. I generally shun the HT type threads, but yours looks very much like a 2ch system. Not the same.

cheers
 

hilde45

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I limited the response because I'm aware that until the bass region is where it could be, the rest can be done more easily (maybe), later.

The persons who relayed how their system improved were actually very grounded and sophisticated audiophiles, some with extensive scientific experimental background and commonsense. I'm not pursuing things because various random people touted them on forums. (Just so you know.)

My system is two channel, and I am quite prepared to come to the conclusion that treatments are *not* necessary. I'm not already decided on buying stuff and searching for a rationale. (Again, just to let you know. You didn't accuse me of that, but it does happen a lot. Fevered hobbyist behavior, and all that.)
 

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3. Tweak the toe in and MLP to produce the best sound and most lifelike imaging. Keep things very symmetrical. if you have access to pink noise you can also play it over both speaker to confirm a good centered image. Then reverse the leads on ONE speaker. You should hear a "hole" between the speakers with the rest of the sound speed evenly out from there, ideally extending even bit outside the speakers. Tweak the toe in while at the listening position slightly. You should find one position were the noise sounds smooth AND the image just locks to a hole in the center. Don't forget to return the leads back to normal polarity when done here.

Thank you so much for this tip. Do you suggest pink noise full range or band limited or pink random in REW?
 

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Thank you hilde45. I have read Floyd"s book several times as well as the edition before it. His measurements, techniques and thoughts are baked into my recommendations. That is not to say I agree with everything said there but certainly the vast majority of it. I am a also a follower of Siegfried Linkwitz, Andrew Jones, Don Keele on the pro audio side and several of the KEF engineers and measurement pioneers. Although my expertise is in measurements I have listened to virtually every system I helped improve personally. Listening as i have said is the final arbiter. I have been doing this since the early 1970's. Out of hundreds of interactions I have never had single encounter with someone who said they did not like the results.

AJ does have good point that a couple of subs would help but not without a proper way to integrate them. That is, a crossover and possibly some EQ. He also gently says there are lots of beliefs and there are lots of beliefs that are wrong. I agree completely. He also says ears do not hear how mics measure, also correct. Since you an I have been working on ways to both improve bass extension, smooth the mid bass a bit and my hidden agenda of lowering the woofer distortion most the the feedback has been in that vein.

Over the 50 years I have been designing speakers and measuring systems I have acquired a little knowledge about what works and what does not. I have never sold a single speaker, tried to sell any books, or charged a single penny for my service. I have no commercial interest to serve or really any fear about making a mistake. Just like the hobby and most of the people in it and try to help to the best of my ability.
I was only the last two years though that I was able to embrace room treatment as a valuable tool in the toolbox to create the best sound. It is not the cheapest way to go nor does one size fit all but it has its uses. But like integrating subs it can not be efficiently done (at least by me) without measurements and the ears are not a calibrated instrument. Once the biggest problems are fixed the ear has to to decide if more work is needed.

I will caution you though. My dear daddy used to say, "A luxury, once sampled become necessity."
 
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linearphase

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Thank you so much for this tip. Do you suggest pink noise full range or band limited or pink random in REW?
Full range is fine. The random version is easier on the ears though worse for measurement. Listening to pink noise is an acquired skill though. It may take an hour or two of the boring stuff to get really good at it. Once the skill is acquired though it is a much more sensitive test than music for many things like setting speaker toe in, fine tuning the listening position, fine tuning EQ, setting octave to octave balance (voicing), listening for resonances, and other uses.
Just move you head left and right and then front and back slightly. With some practice the sound will just snap into focus. That is the right spot.
You don't have to listen with your head in a vise, good sound can be had in the vicinity, but this is the only spot where it will be the best it can be.
Let us know how it works for you.
 
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hilde45

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Thank you, linearphase.

I've copied your experiment into a separate document and separated each stage. I'll try to do the experiment later today or tomorrow and will post results.

I'll answer a couple questions you asked with an attached photo. Basically, a concrete floor with thin carpet. Ceiling is drywall.

Hi linearphase,
Did the measurements as best I could, and because there was clipping, I had to adjust the levels a bit. I attempted to offset measurements so the were all aligned. Hope this is decent data. I have an uncorrected set if this one is messed up.
Thank you hilde45. I have read Floyd"s book several times as well as the edition before it. His measurements, techniques and thoughts are baked into my recommendations. That is not to say I agree with everything said there but certainly the vast majority of it. I am a also a follower of Siegfried Linkwitz, Andrew Jones, Don Keele on the pro audio side and several of the KEF engineers and measurement pioneers. Although my expertise is in measurements I have listened to virtually every system I helped improve personally. Listening as i have said is the final arbiter. I have been doing this since the early 1970's. Out of hundreds of interactions I have never had single encounter with someone who said they did not like the results.

AJ does have good point that a couple of subs would help but not without a proper way to integrate them. That is, a crossover and possibly some EQ. He also gently says there are lots of beliefs there are lots of beliefs are wrong. I agree completely. He also says ears do not hear how mics measure, also correct. Since you an I have been working on ways to both improve bass extension, smooth the mid bass a bit and my hidden agenda of lowering the woofer distortion most the the feedback has been in that vein.

Over the 50 years I have been designing speakers and measuring systems I have a acquired a little knowledge about what works and what does not. I have never sold a single speaker, tried to sell any books, or charged a single penny for my service. I have no commercial interest to serve or really any fear about making a mistake. just like the hobby and most of the people in it and try to help to the best of my ability.
I was only the last two years though that I was able to embrace room treatment as a valuable tool in the toolbox to create the best sound. It is not the cheapest way to go nor does one size fit all but it has its uses. But like integrating subs it can not be efficiently done (at least by me) without measurements and the ears are not a calibrated instrument. Once the biggest problems are fixed the ear has to to decide if more work is needed.

I will caution you though. My dear daddy used to say, A luxury, once sampled become necessity.

Linearphase,

I consider myself quite privileged to have your attention and your expert opinion. Thank you.
 

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  • feb 9 sub center front mains gain crossover changes HILDE45 avnirvana.mdat
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linearphase

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Hi linearphase,
Did the measurements as best I could, and because there was clipping, I had to adjust the levels a bit. I attempted to offset measurements so the were all aligned. Hope this is decent data. I have an uncorrected set if this one is messed up.


Linearphase,

I consider myself quite privileged to have your attention and your expert opinion. Thank you.
Thanks but it is my pleasure.
Working right now to get some paper work processed. We are taking in a homeless lady who has had a really hard time the last few years. Trying to help her out.
Will get back to you as soon I can get it done and look at your data. BTW don't ever feel obligated to do any of these things I suggest. I have learned so much about Room acoustics thanks to REW being a great evolving platform. I used to have to drive to people's houses to measure and help because my software was very difficult to use not FREE. It could easily take 100 hours of driving and on site time to optimize a system. Now I can help people throughout the world over the internet in a tiny fraction of that time. It is a great way to learn.
 
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linearphase

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OK the clipping is an issue, waveform very distorted. Please make mains to front wall 72", repeat L plus sub@65Hz crossover mic at MLP ( the mic for now should be at your ear level center of head.) Increase the gain on the sub 3dB if you can. (later we will make multi mic or moving mic measurements. Toe in speaker so left axis points at last ear, right at right ear.
Do 2 sweeps 0 degrees phase then 180. Make sure there is no clipping anytime during the sweep. Are you using a UMIK1?

BTW this looks like ballpark settings if the sweep is not totally clipped. 0 degree phase is better. Give it a listen sub on sub off and comment.

Later if you can find the time:
1. Move the equipment between the speakers to the front wall.
2. Move the computer behind the MLP,, close the screen when not listening.
This will make a subtle audible change but will improve our measurements a lot. Right now there are enough reflections that it is hard to see the forrest for the trees.

3. Right now the biggest impediment to clarity is the huge reflection at about 1.8mS. If we can get this down in level it would be good. I think it is a ceiling bounce.
If you want to go for it we need to positively Identify the offending surface. You can build a little tool that I use every day. I build them and give to audio friends but am out at the moment. Goggle Calibrated acoustic string and print out the instructions. This is just a way to build a device that measures in time. It is calibrated in mS (.001S) rather than feet. Very useful when you are looking for a bounce or reflection that delays the sound by 1.8mS. The instructions explain how to use it. In a pinch a piece of string and some tape is all you need.
Here is a little cheat sheet I made.
 

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hilde45

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Linearphase,
First, kudos on helping out the homeless person. You have a good soul.
I am using a UMIK1.
I will try to get going on these measurements soon. I *knew* I should not have set up all my tube gear! It took forever to setup again. I will get it out of the way. Of course, if it needs to live there or nearby, wouldn't the scans be more accurate with it in the picture? I suppose the down-the-road answer will involve something like long speaker cables, or some long interconnects, right?
 
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hilde45

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Linearphase,
First, kudos on helping out the homeless person. You have a good soul.
I am using a UMIK1.
I will try to get going on these measurements soon. I *knew* I should not have set up all my tube gear! It took forever to setup again. I will get it out of the way. Of course, if it needs to live there or nearby, wouldn't the scans be more accurate with it in the picture? I suppose the down-the-road answer will involve something like long speaker cables, or some long interconnects, right?

Linearphase, all, here are some new scans. I moved all my gear out of the way except one integrated amp. Laptop out of the way.

Gist: Sub front wall, center. Mic at 1" from sub, and then at MLP. Sub crossover at 65hz. Sub gain at 9pm first, then increased to 12 noon. Sub Phase varying from 0 to 180. Main speakers playing: L only, mostly, but a couple baseline scans are there, too.
 

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linearphase

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Linearphase,
First, kudos on helping out the homeless person. You have a good soul.
I am using a UMIK1.
I will try to get going on these measurements soon. I *knew* I should not have set up all my tube gear! It took forever to setup again. I will get it out of the way. Of course, if it needs to live there or nearby, wouldn't the scans be more accurate with it in the picture? I suppose the down-the-road answer will involve something like long speaker cables, or some long interconnects, right?
Yes, although many people like to place their audio gear between the speakers it is actually the worst place to put it acoustically. In that regard the best place is out of the room or at least on one sidewalk behind the first reflection point.
Tube gear has very high input impedance typically which makes it susceptible to response changes and noise pickup with long. Input leads. You are probably better off using longer speaker cables of suitably large guage.
 

linearphase

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Linearphase, all, here are some new scans. I moved all my gear out of the way except one integrated amp. Laptop out of the way.

Gist: Sub front wall, center. Mic at 1" from sub, and then at MLP. Sub crossover at 65hz. Sub gain at 9pm first, then increased to 12 noon. Sub Phase varying from 0 to 180. Main speakers playing: L only, mostly, but a couple baseline scans are there, too.

First this is now good response, congratulations! To get it much better will require EQ and some judicious room treatment.
It appears there may still be some issues with the measurements. Measurements labelled the same are significantly different. Do you have any noise in your room?
I hate to be such pain but can you run once more with just 2 curves?
1. Sub with left at MLP, cross@65, gain 9PM, phase 0 then 180. Make sure the mic tip is right where the center of your head would be. I would point the mic at the speaker being measured, I know many say it doesn't mater by it does make slight differences at high frequencies. Make sure you use the 0 degree mic cal file.
No need to run the 1" curve anymore.
Then listen a bit at the 180 degree position. Tweak the sub level up and down from there and make a note or mark at the level you prefer. Then just listen for a while. It should sound pretty good if these curves are representative. Let us know what you hear, good or bad.
 
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hilde45

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First this is now good response, congratulations! To get it much better will require EQ and some judicious room treatment.
It appears there may still be some issues with the measurements. Measurements labelled the same are significantly different. Do you have any noise in your room?
I hate to be such pain but can you run once more with just 2 curves?
1. Sub with left at MLP, cross@65, gain 9PM, phase 0 then 180. Make sure the mic tip is right where the center of your head would be. I would point the mic at the speaker being measured, I know many say it doesn't mater by it does make slight differences at high frequencies. Make sure you use the 0 degree mic cal file.
No need to run the 1" curve anymore.
Then listen a bit at the 180 degree position. Tweak the sub level up and down from there and make a note or mark at the level you prefer. Then just listen for a while. It should sound pretty good if these curves are representative. Let us know what you hear, good or bad.

I suspect that user error keeps creeping into my measurement labelling or...I don't know what else. I wonder if there is an issue with my sub causing some problems. Hmmm.

Anyway, I will do these new scans and carefully label them. I'll do each scan twice, too before changing the settings.

I've copied out your instructions and will print and execute later this morning. (You know, when my family is awake!)

p.s. Not sure where you meant the best place for gear would be -- along the side (got that) but in FRONT of the 1st side reflection point (closer to the front wall, i.e., the wall I look at while listening) or BEHIND the 1st reflection point (closer to the rear wall).
 
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