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Discussion Starter #701
Tuning the Room

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I posted something on the SVS thread today that I thought I might repeat here for the benefit of people who check this thread occasionally. I had responded earlier to a question from someone who noticed that his very low-frequency SPL increased when he opened a door to his sealed room. He wondered if there were any negatives associated with doing that. I told him that I had tried that same technique several years ago, before I had quite as much subwoofage as I wanted, and it also worked for me, with no drawbacks.

He then wondered why people so often make a fuss about having sealed rooms. My response is below. I don't think that this is something that I want to try to add to the Guide right now, but some discussion here might be interesting. Anyone who currently has a sealed room, and who wants even more very low-frequency SPL can easily experiment with opening one or more doors to the room, to see if it makes a difference. I used to actually open two doors to my large sealed room. And, I experimented to discover just what combination of opening (I opened one about 4" - 6" and the other about 18" - 24" as I recall) gave me the most additional low-frequency SPL and tactile response. All of this was occurring below 30Hz.

It's just something else that might be fun to try (and/or to measure) if anyone is interested in doing that. :)


"I think that the relationship between a room, and bass SPL, is a very interesting subject. And, it's one that I tried to address in Section VII of the Guide, linked below. (There is a whole subsection on room gain, including pressure vessel gain.) I believe that there are a lot of misconceptions about bass. One of them involves the idea of "pressurizing" a room with bass. Most people take the idea of bass "pressurization" to mean an increase in bass SPL to Reference levels.

But, a room is "pressurized" with bass when low-frequency sound pressure levels create physical sensations of pressure against certain parts of our bodies. And, that physical pressure against our ear drums (and our faces) first, and eventually against other parts of our bodies, is easier to achieve in a small, tightly-sealed room. That physical sensation of pressure from low-frequency SPL is quite similar to the sensation we feel when the cabin of an airplane pressurizes, or when we dive 8' or 10' underwater.

Whether or not someone actually likes that physical sensation is another question. Personally, I don't particularly like it. But, sealing a room and playing very high bass volumes, at very low-frequencies, can definitely allow us to feel bass pressurization. Simply achieving sufficient low-bass sounds and tactile sensations to satisfy us, without putting excessive pressure against our ear drums or other parts of our bodies, is something else though. A room doesn't have to be sealed in order to accomplish that, nor does it have to be very small. It's just a little harder to achieve satisfactory low-bass SPL and tactile ULF in a large room, which is open to other spaces. And, it may take more subwoofers, which are capable of hitting low-frequencies, and considerable subwoofer boosts to accomplish it.

I am not entirely sure why opening a door in a sealed room can change the "tuning" of a room. I think of it as something like changing the port tuning of a ported subwoofer in order to enable it to produce more SPL at lower frequencies. It's not an exact analogy, but it helps me to understand it a little better. I have also heard the idea that opening a door compares somewhat to creating a Helmholtz resonator, which generates more SPL at a particular frequency. That's the same basic concept as the port tune.

In any event, I know from anecdotal discussions and from personal experience that it can work, and I don't know of any negatives associated with it. When I experimented with the idea several years ago, I found that I could increase or decrease the intensity of the low-bass SPL by how much I opened the door. It was pretty cool, although it could be a little too much at times with just the right material. I believe that it literally creates a peak at a particular frequency, or at a narrow range of frequencies, similar to the PEQ peak at 63Hz that SVS programs into the DSP of some of their subwoofers. (It would be interesting for you to measure this, to see what frequencies are involved, and how much additional SPL you are gaining.)

One thing that I do know is that even very thick bass traps, with air pockets behind them, are not going to have a meaningful effect on frequencies below about 60Hz. So, if someone is struggling with cancellation at very low-frequencies, and changing the distance or phase on one of his subwoofers doesn't help, then trying to tune the room differently might be a viable alternative. I really do recommend bass traps though, and especially broadband ones, to reduce ringing in a room and to increase overall bass clarity."


Regards,
Mike
 

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------

I posted something on the SVS thread today that I thought I might repeat here for the benefit of people who check this thread occasionally. I had responded earlier to a question from someone who noticed that his very low-frequency SPL increased when he opened a door to his sealed room. He wondered if there were any negatives associated with doing that. I told him that I had tried that same technique several years ago, before I had quite as much subwoofage as I wanted, and it also worked for me, with no drawbacks.

He then wondered why people so often make a fuss about having sealed rooms. My response is below. I don't think that this is something that I want to try to add to the Guide right now, but some discussion here might be interesting. Anyone who currently has a sealed room, and who wants even more very low-frequency SPL can easily experiment with opening one or more doors to the room, to see if it makes a difference. I used to actually open two doors to my large sealed room. And, I experimented to discover just what combination of opening (I opened one about 4" - 6" and the other about 18" - 24" as I recall) gave me the most additional low-frequency SPL and tactile response. All of this was occurring below 30Hz.

It's just something else that might be fun to try (and/or to measure) if anyone is interested in doing that. :)


"I think that the relationship between a room, and bass SPL, is a very interesting subject. And, it's one that I tried to address in Section VII of the Guide, linked below. (There is a whole subsection on room gain, including pressure vessel gain.) I believe that there are a lot of misconceptions about bass. One of them involves the idea of "pressurizing" a room with bass. Most people take the idea of bass "pressurization" to mean an increase in bass SPL to Reference levels.

But, a room is "pressurized" with bass when low-frequency sound pressure levels create physical sensations of pressure against certain parts of our bodies. And, that physical pressure against our ear drums (and our faces) first, and eventually against other parts of our bodies, is easier to achieve in a small, tightly-sealed room. That physical sensation of pressure from low-frequency SPL is quite similar to the sensation we feel when the cabin of an airplane pressurizes, or when we dive 8' or 10' underwater.

Whether or not someone actually likes that physical sensation is another question. Personally, I don't particularly like it. But, sealing a room and playing very high bass volumes, at very low-frequencies, can definitely allow us to feel bass pressurization. Simply achieving sufficient low-bass sounds and tactile sensations to satisfy us, without putting excessive pressure against our ear drums or other parts of our bodies, is something else though. A room doesn't have to be sealed in order to accomplish that, nor does it have to be very small. It's just a little harder to achieve satisfactory low-bass SPL and tactile ULF in a large room, which is open to other spaces. And, it may take more subwoofers, which are capable of hitting low-frequencies, and considerable subwoofer boosts to accomplish it.

I am not entirely sure why opening a door in a sealed room can change the "tuning" of a room. I think of it as something like changing the port tuning of a ported subwoofer in order to enable it to produce more SPL at lower frequencies. It's not an exact analogy, but it helps me to understand it a little better. I have also heard the idea that opening a door compares somewhat to creating a Helmholtz resonator, which generates more SPL at a particular frequency. That's the same basic concept as the port tune.

In any event, I know from anecdotal discussions and from personal experience that it can work, and I don't know of any negatives associated with it. When I experimented with the idea several years ago, I found that I could increase or decrease the intensity of the low-bass SPL by how much I opened the door. It was pretty cool, although it could be a little too much at times with just the right material. I believe that it literally creates a peak at a particular frequency, or at a narrow range of frequencies, similar to the PEQ peak at 63Hz that SVS programs into the DSP of some of their subwoofers. (It would be interesting for you to measure this, to see what frequencies are involved, and how much additional SPL you are gaining.)

One thing that I do know is that even very thick bass traps, with air pockets behind them, are not going to have a meaningful effect on frequencies below about 60Hz. So, if someone is struggling with cancellation at very low-frequencies, and changing the distance or phase on one of his subwoofers doesn't help, then trying to tune the room differently might be a viable alternative. I really do recommend bass traps though, and especially broadband ones, to reduce ringing in a room and to increase overall bass clarity."


Regards,
Mike

In deed, a very interesting subject, and also do not like real deep bass, 20Hz and above is enough for me:)

While many time, I do preach about open room trying to fill all open area, compare to a close one.
Mine, is also open a little from the curtains at the bottom stairs of the my Theater entrance, and not been a door.

Mind you, I did got two PB13 subs, when only one was require, because of this.
Looking forward to read, other members impression.


Ray
 

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Mike, thanks for the excellent and detailed information in this thread.

I searched but did not find any reference to Passive Radiator (PR) in subs, what is your opinion on these compared to sealed subs?

I have just ordered a BK P12-300SB-PR which has 12” front-firing active and 12” down-firing passive drivers. My room is open plan and ~4800^3 ft.
 

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Discussion Starter #704 (Edited)
Mike, thanks for the excellent and detailed information in this thread.

I searched but did not find any reference to Passive Radiator (PR) in subs, what is your opinion on these compared to sealed subs?

I have just ordered a BK P12-300SB-PR which has 12” front-firing active and 12” down-firing passive drivers. My room is open plan and ~4800^3 ft.

Hi Russ,

You are very welcome! I am glad if Guide has been helpful. (And, I have put some comments on passive radiators in there at the end of Section VIII-A, on sealed and ported subs.)

I'm not quite sure why passive radiators aren't more popular. Unfortunately, I haven't seen many (if any) good head-to-head comparisons, so I have to speculate a little about them. Passive radiators offer some of the advantages of ported subwoofers, in that they amplify the effect of the driver at certain frequencies. And, they do it without any possibility of port chuffing.

A passive radiator can allow a 12" subwoofer to be more powerful, at low-frequencies, than a comparable sealed subwoofer. And, it can accomplish that in a smaller cabinet volume than a ported sub would require, since the ports themselves consume much of the volume of a ported cabinet. The diameter and length of the ports determine the ported sub's tuning point, so if we want to go low, the cabinet has to be pretty big.

I believe that passive radiators cannot produce quite as much additional SPL, as a ported subwoofer, tuned to the same frequency. And, they won't produce quite as much tactile energy as the ported subwoofer does, with its ports also moving air. But, it seems to me, that passive radiators can be an excellent way to achieve additional low-frequency SPL in a relatively compact cabinet. I hope that this brief comparative description helps.

Your subwoofer looks very nice from the review I just read. I hope that you will post about your impressions of it once you have had an opportunity to enjoy it. :)

Regards,
Mike


Edit: The review I read was here: https://www.avforums.com/review/bk-electronics-p12-300sb-subwoofer-review.11864
 

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Thanks, Mike. I will post my impressions after I have it up and running.
Please could you point me to the review you read, as I have not seen one of the PR model yet.
 
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Hi Russ,


I'm not quite sure why passive radiators aren't more popular. Unfortunately, I haven't seen many (if any) good head-to-head comparisons, so I have to speculate a little about them. Passive radiators offer some of the advantages of ported subwoofers, in that they amplify the effect of the driver at certain frequencies. And, they do it without any possibility of port chuffing.
I'm guessing from a comment or two from Tom V recently about his prototype, that maybe passive radiators aren't as good value for money as ported.

https://www.avsforum.com/forum/113-subwoofers-bass-transducers/1372020-official-power-sound-audio-subwoofer-thread-449.html#post56856724
 

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Discussion Starter #707
I'm guessing from a comment or two from Tom V recently about his prototype, that maybe passive radiators aren't as good value for money as ported.

https://www.avsforum.com/forum/113-subwoofers-bass-transducers/1372020-official-power-sound-audio-subwoofer-thread-449.html#post56856724

Thanks, I think you are right! According to what I have read, the design work would only be a little more time consuming, but the biggest difference would be in the cost of the passive radiator. It would be another woofer just like the active driver in the sub, although it would be a little larger than the operational one.

The passive radiator would not have a voice coil, or a magnet, and it would not be connected to the subwoofer's amplifier. Its diameter and mass would determine its tuning frequency, and it would move in-and-out, in coordination with the active driver, entirely due to air pressure within the cabinet. I know that Nathan Funk, of Funk Audio, has made some passive radiators on request, and I have always wondered what they sound like. They should be somewhat similar in both sound and tactile response to a sealed subwoofer, since there wouldn't be any ports to move air.

Regards,
Mike
 

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I'm guessing from a comment or two from Tom V recently about his prototype, that maybe passive radiators aren't as good value for money as ported.

https://www.avsforum.com/forum/113-subwoofers-bass-transducers/1372020-official-power-sound-audio-subwoofer-thread-449.html#post56856724

Nice find:)

Tom V, always give his honest opinion, even when it come to the competition, as seen from his reply on the third post of this thread;
https://www.avsforum.com/forum/113-subwoofers-bass-transducers/3005586-buying-first-high-end-sub-need-advice.html#post56884100

A man of great integrity!


Ray
 

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Hi and thank you both for a swift response.
...
Again thanx for the insight about those two partial walls, it will be interesting to hear the difference and figuring out where the subwoofers sounds the best.

Cheers,
//Peter
Hi again,
I need some more guidance regarding my new subwoofer setup.
I posted here a couple of weeks ago regarding buying SVS SB2000.

I have spent this week tweaking my system, with REW and a UMIK mic, and I would very much appreciate someone to look at and comment the following.

For reference:
AVR = Marantz 7011
Sub: Two SVS SB2000
Speakers: LINN UNIK (80Hz-20kHz)

AVR settings:
Speakers set to small
Crossover: 100hz
LPF for LFE: 120hz
Subwoofer levels set to -7,5 db (running 4db hot, Audyssey set the levels to -12,5db)
Distance to sub: 12 feet

Subwoofer settings:
Low pass filter set to LFE
Phase dial set to 9 o’clock on Left sub and 3o’clock on right sub
Volume set to 2 out of ten (Audyssey set the level)

This is my apartment layout
Apartment layout.PNG

This is the placement of the two subs and front speakers
Sub placement.jpg

This is my phase tweaks
Phase tweak.PNG

This is my distance tweaks
Distance tweak.PNG

This is the difference between calibrating with the Audyssey multeq editor app and with the Marantz AVR.
APP vs MAR.PNG

This is my current (reference) curve as of now
Reference.PNG



Ok, with that out of the way, here are some observation and questions.

I have made phase tweaks to dial in a better frequency curve, see “Phase tweak.PNG”.
Question: is there anything else I can do to tweak that setting?

I have made distance tweaks to dial in a better frequency curve, see “Distance tweak.PNG
”. The suggested 12 feet is in my mind the best setting
Question: is there anything else I can do to tweak that setting?

Regarding my current frequency curve.
Question: How does that curve look to you?

There is quite a difference when making the initial setup with the Marantz AVR versus Audyssey multeq editor app.
Question: Any comments on why there is such a difference?


I have had a great time tweaking the system and are now soon ready to listen to it as well ;-)
I appreciate any response and suggestions.



Best regards,
//Peter
 

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Discussion Starter #710 (Edited)
Hi again,
I need some more guidance regarding my new subwoofer setup.
I posted here a couple of weeks ago regarding buying SVS SB2000.

I have spent this week tweaking my system, with REW and a UMIK mic, and I would very much appreciate someone to look at and comment the following.

For reference:
AVR = Marantz 7011
Sub: Two SVS SB2000
Speakers: LINN UNIK (80Hz-20kHz)

AVR settings:
Speakers set to small
Crossover: 100hz
LPF for LFE: 120hz
Subwoofer levels set to -7,5 db (running 4db hot, Audyssey set the levels to -12,5db)
Distance to sub: 12 feet

Subwoofer settings:
Low pass filter set to LFE
Phase dial set to 9 o’clock on Left sub and 3o’clock on right sub
Volume set to 2 out of ten (Audyssey set the level)

This is my apartment layout
Apartment layout.PNG

This is the placement of the two subs and front speakers
Sub placement.jpg

This is my phase tweaks
Phase tweak.PNG

This is my distance tweaks
Distance tweak.PNG

This is the difference between calibrating with the Audyssey multeq editor app and with the Marantz AVR.
APP vs MAR.PNG

This is my current (reference) curve as of now
Reference.PNG



Ok, with that out of the way, here are some observation and questions.

I have made phase tweaks to dial in a better frequency curve, see “Phase tweak.PNG”.
Question: is there anything else I can do to tweak that setting?

I have made distance tweaks to dial in a better frequency curve, see “Distance tweak.PNG
”. The suggested 12 feet is in my mind the best setting
Question: is there anything else I can do to tweak that setting?

Regarding my current frequency curve.
Question: How does that curve look to you?

There is quite a difference when making the initial setup with the Marantz AVR versus Audyssey multeq editor app.
Question: Any comments on why there is such a difference?


I have had a great time tweaking the system and are now soon ready to listen to it as well ;-)
I appreciate any response and suggestions.


Best regards,
//Peter

Hi Peter,

First of all, congratulations! I believe you will enjoy your new SB2000's. I think your frequency response looks pretty good. You are getting a nice low-frequency house curve, due to room gain. And, some people would like the peak at about 65Hz. That is right in the middle of what most people would characterize as the chest punch frequency range. In fact, on some of SVS's higher end subs, they have a pre-programmed peak at 63Hz that people can add.

I see that your subwoofers are very symmetrically arranged. Did you try some other, non-symmetrical arrangements before settling on this one, or did you just position the subs and then tweak them to get the best response you could? Sometimes even relatively small adjustments, such as rotating one or both subs 90 degrees, can make a difference.

Changing the way the subs face won't change the SPL they produce, but it may influence their frequency response in some fashion. The same thing would happen if you put one sub somewhere else besides the front wall. Since you have REW, and you enjoy tweaking, this is something that you could explore at your convenience.

I think that the most important question, though, is how do you think things sound now? I would devote some time to listening now. The low-bass house curve would definitely appeal to most people, and the peak at 65Hz may also appeal to you. There are also quite a few settings that you can experiment with at your leisure. Some of them such as Audyssey Flat versus Audyssey, and DEQ off versus DEQ on, can change the overall sound somewhat. It's fun to try the different options, and the Guide explains how they work.

To answer your other questions, other than experimenting with the specific positioning of your subwoofers, and perhaps trying an 80Hz crossover, instead of a 100Hz crossover, I can't think of any other suggestions to make right now. I also can't explain why the Audyssey app produces different results, but a number of other users have observed the same thing. The software is slightly different, so where the results are different, most people just go with the version that they like best. From what I have observed, the AVR version is usually a little more reliable, but the app offers more user adjustability. So, it's strictly a YMMV situation--like most things in audio. :)

Regards,
Mike


Edit: I see that @darthray also has some observations.
 

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Hi Peter,

First of all, congratulations! I believe you will enjoy your new SB2000's. I think your frequency response looks pretty good. You are getting a nice low-frequency house curve, due to room gain. And, some people would like the peak at about 65Hz. That is right in the middle of what most people would characterize as the chest punch frequency range. In fact, on some of SVS's higher end subs, they have a pre-programmed peak at 63Hz that people can add.

I see that your subwoofers are very symmetrically arranged. Did you try some other, non-symmetrical arrangements before settling on this one, or did you just position the subs and then tweak them to get the best response you could? Sometimes even relatively small adjustments, such as rotating one or both subs 90 degrees, can make a difference.

Changing the way the subs face won't change the SPL they produce, but it may influence their frequency response in some fashion. The same thing would happen if you put one sub somewhere else besides the front wall. Since you have REW, and you enjoy tweaking, this is something that you could explore at your convenience.

I think that the most important question, though, is how do you think things sound now? I would devote some time to listening now. The low-bass house curve would definitely appeal to most people, and the peak at 65Hz may also appeal to you. There are also quite a few settings that you can experiment with at your leisure. Some of them such as Audyssey Flat versus Audyssey, and DEQ off versus DEQ on, can change the overall sound somewhat. It's fun to try the different options, and the Guide explains how they work.

To answer your other questions, other than experimenting with the specific positioning of your subwoofers, and perhaps trying an 80Hz crossover, instead of a 100Hz crossover, I can't think of any other suggestions to make right now. I also can't explain why the Audyssey app produces different results, but a number of other users have observed the same thing. The software is slightly different, so where the results are different, most people just go with the version that they like best. From what I have observed, the AVR version is usually a little more reliable, but the app offers more user adjustability. So, it's strictly a YMMV situation--like most things in audio. :)

Regards,
Mike

As usual, always a good reply with all the answer for the important points.

The first thing I notice, was both subs are equidistance to MLP, and myself, I would use both phase at 0 degree, instead of 45 & 135. And let the calibration system do it's things after calibration. While I could understand different phase if they were at different placement in the room. And very important to try different scenario. This one do not make sense to me, and should be the same at their present location.

Also agree with experimenting with front three speakers, to try a 80 Hz setting, instead of 100. and also trying between with Audyssey curve or Audyssey Flat, and DEQ On or Off. Since I prefer "Flat with DEQ Off", as you already know.

As we both know, location, location and location are the most important. Then playing with the curve been Flat or House Curve/DEQ On or Off, are part of the tweaking process. I was just lucky with my personal present location to have good results.


Ray
 

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Is your crossover on the subwoofer amp set all the way to maximum (250hz etc) or "bypass"? They will compound each other (100hz on sub and 80hz in the receiver) if not.
If not then disregard!
 

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Hello and thank you for a quick response,
I’m happy to read that you think my low-frequency house curve is good and that I’m on the right track and that that bump around 65hz is actually a feature that can be enjoyed. :)

I appreciate the answers and will most definitely try to experiment some more now.

To answer your questions and to further report on what I have done prior to the first post.
I have tried to set the crossovers all over the place, from 60hz up to I think 250hz with the 100hz being the best overall setting.
I have also tried moving the subs around and placing one sub at the opposite wall with not that good of a result. There are not that many places where I can place the subs in my listening room. Moving the subs more to the left and right didn’t do that much in terms on frequency response. I have also tried to corner load the right sub but that didn’t do that much either in regards of a better curve. I have actually moved the subs a little closer together without suffering anything in terms of frequency response. I have read that moving the sub just an inch or two could have dramatic changes but for me that is not the case.

Regarding the phase tweak, I did have them at 0 degree when doing the Audyssey setup, it is after that initial setup that I applied the phase tweak. As you can see in my attachment the frequency response varies quite a bit when I try different phases. I wonder if me irregular shaped room is making my 45/135-degree tweak necessary? I attach a picture that better illustrate the big difference between these two settings. (Phase difference.png)

I will play some more with the different Audyssey setups, and I will definitely try to turn the subs and see what that does. Great suggestions that I haven’t thought of.

I have had some time to listen to my new subs and I’m pleased with the result. The difference from my previous sub is very noticeable and I truly enjoy my new richer sound, especially while watching movies. I attach a measurement between my two subs as a comparison. (SVS vs REL.png)



As always, great and insightful answers from this community.



Enjoy the weekend!
//Peter
 

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Is your crossover on the subwoofer amp set all the way to maximum (250hz etc) or "bypass"? They will compound each other (100hz on sub and 80hz in the receiver) if not.
If not then disregard!
Hi brettus,
Yes, they are both at LFE bypass.

I actually played around with what I think is cascading crossover but didn't think I got that great of a result so I have landed in having both subs dialed in with LFE bypass.

//P
 

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Hello and thank you for a quick response,
I’m happy to read that you think my low-frequency house curve is good and that I’m on the right track and that that bump around 65hz is actually a feature that can be enjoyed. :)

I appreciate the answers and will most definitely try to experiment some more now.

To answer your questions and to further report on what I have done prior to the first post.
I have tried to set the crossovers all over the place, from 60hz up to I think 250hz with the 100hz being the best overall setting.
I have also tried moving the subs around and placing one sub at the opposite wall with not that good of a result. There are not that many places where I can place the subs in my listening room. Moving the subs more to the left and right didn’t do that much in terms on frequency response. I have also tried to corner load the right sub but that didn’t do that much either in regards of a better curve. I have actually moved the subs a little closer together without suffering anything in terms of frequency response. I have read that moving the sub just an inch or two could have dramatic changes but for me that is not the case.

Regarding the phase tweak, I did have them at 0 degree when doing the Audyssey setup, it is after that initial setup that I applied the phase tweak. As you can see in my attachment the frequency response varies quite a bit when I try different phases. I wonder if me irregular shaped room is making my 45/135-degree tweak necessary? I attach a picture that better illustrate the big difference between these two settings. (Phase difference.png)

I will play some more with the different Audyssey setups, and I will definitely try to turn the subs and see what that does. Great suggestions that I haven’t thought of.

I have had some time to listen to my new subs and I’m pleased with the result. The difference from my previous sub is very noticeable and I truly enjoy my new richer sound, especially while watching movies. I attach a measurement between my two subs as a comparison. (SVS vs REL.png)



As always, great and insightful answers from this community.



Enjoy the weekend!
//Peter

It is obvious to me, that you did all your homework, with your subs:D
Very nice graph, by the way, they speak a thousand words, very well done!

For your choices for the phases, I now see why you went with 45 & 135 degrees, instead of 0.
The difference is very drastic.

I went back to check your room again, and honestly do not know if it is the reason for such a difference. But very possible since subs are very picky beast, when it come to location and the room shape, for your MLP:eek:

Thanks for the compliment, for this community. It is a very nice place to hang on, to learn and help others when we can.
Also glad you are enjoying your new toys.


Ray
 

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Hi,
First off, thanks mike, for starting this thread and all the help you give to this community and thanks to all the contributors in the thread as well
I have a dedicated 20x28x10 home theater with (4) rythmik fv15hp’s up front, 2 in each corner stacked on top of each other.
I have a 185” diagonal 16:9 screen so my MLP is 17’ from the screen, which puts me 20’ back from the subwoofers.
I found out recently that my neighbors houses are getting a lot of vibration from my system so I’m going to move the subwoofers closer to my MLP in hopes that will solve the problem.
My 2 choices would be to put them on the rear wall at the 1/4 points double stacked or put 1 at each of those spots and also place 1 at each of the rear 1/4 spots on the side walls, which puts one just in front of each side of my seats.The ones in the rear would be about 7’ from MLP and the ones on the side wall would be about 9’ away.
I plan on setting up both ways and trying them out, I’m just wondering if either of the possibilities stands out as a better choice.
FYI- I’m not in an apartment, my closest neighbor is 75’ away and moving the subs closer to my MLP is also moving them further from my neighbors
Thank you,


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Hi,
First off, thanks mike, for starting this thread and all the help you give to this community and thanks to all the contributors in the thread as well
I have a dedicated 20x28x10 home theater with (4) rythmik fv15hp’s up front, 2 in each corner stacked on top of each other.
I have a 185” diagonal 16:9 screen so my MLP is 17’ from the screen, which puts me 20’ back from the subwoofers.
I found out recently that my neighbors houses are getting a lot of vibration from my system so I’m going to move the subwoofers closer to my MLP in hopes that will solve the problem.
My 2 choices would be to put them on the rear wall at the 1/4 points double stacked or put 1 at each of those spots and also place 1 at each of the rear 1/4 spots on the side walls, which puts one just in front of each side of my seats.The ones in the rear would be about 7’ from MLP and the ones on the side wall would be about 9’ away.
I plan on setting up both ways and trying them out, I’m just wondering if either of the possibilities stands out as a better choice.
FYI- I’m not in an apartment, my closest neighbor is 75’ away and moving the subs closer to my MLP is also moving them further from my neighbors
Thank you,

Sent from my iPhone using Tapatalk

Hi,

You are very welcome! I hope that the Guide is helpful, and that the thread is a good place to talk about anything audio-related. :)

I think that you are just going to have to experiment to determine what subwoofer arrangement works best. But, I will make some observations. First, it sounds as if you have a very nice HT, and four FV15's should be giving you some good bass. I would not personally choose to stack ported subwoofers, in pairs like that. Instead, I would spread them out around the room. So, my first test arrangement would be to put one sub in each of the four corners of the room. And, my second would be to test four 1/4 wall locations.

Spreading the subs out that way, on multiple walls, will engage more room modes and should result in a more uniform frequency response throughout the room. If, in the process, you get rid of some dips in the FR, you may find that you don't need quite as much bass boost to enjoy the same master volume levels.

You didn't mention your typical listening levels or how much subwoofer boost you are adding post-calibration. When you put one pair of subs in the rear of the room, you may find that you need to reverse the phase on those two rear subwoofers by up to 180 degrees in order to avoid some cancellation. That is part of the trial-and-error process of repositioning the subs.

You can certainly try putting all four subwoofers behind you. The advantage of doing that is that you would be much closer to your subs, and you shouldn't need as much subwoofer volume to hear the same amount of bass. But, you will lose the advantage of potentially improving the FR, so that's just something to determine by listening, or by measuring if you have REW.

The biggest disadvantage of having all four subwoofers toward the rear of the room (other than the probably less effective FR) would be some probable bass localization. I would definitely be able to localize the bass if all of my subs were somewhat behind me and a long way from the action occurring on the screen. But, this is something that you will have to test to determine whether this is something that you notice, and if so, whether it really annoys you. I have four large ported subwoofers, and spread around the room on separate walls, they give me a sensation of bass envelopment that is very appealing. But, that's a YMMV situation as to what we notice, and what we like.

Frankly, my hope in this situation would be that moving two of the subwoofers closer to you will enable you to experience the same good bass sounds and sensations at a slightly lower volume. And, that the combination of lower bass volume, and greater distance (from your neighbors house) for two of the subwoofers will be just enough to satisfy him. If not, then you may, in fact, have to move all of the subwoofers closer to your listening position.

Even if you do get to that point, though, I would still probably try to spread the subwoofers out on three of the walls. And, there would be multiple combinations you could try. For instance, you could try 1/2 wall on the two side walls; and corners, or 1/4 wall, on the back wall. Or, you could try 1/4 walls on all three walls, with the front two near the front wall, but not actually on that wall that faces your neighbor. Stacking the subs anywhere would probably be my last resort, but who knows? That could conceivably be the best final arrangement. That's the trial-and-error aspect of this.

I see this as an equation with multiple variables. There is how much vibration your neighbor perceives; there is how much bass you perceive; there is whether you have an audibly or measurably decent FR, without a lot of random peaks and dips in bass volume; and there is whether the bass can be localized, and whether or not enough of it seems to come from the front sound stage to adequately support the movie?

I will be very interested to hear what you discover, so please come back to let us all know. And, if you can get close on the issue of localization, with 1/4 or 1/2 side walls, for instance, there are a couple of things you could try in order to reduce the localization effect a little more. Keep me posted! :)

Regards,
Mike
 

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It is obvious to me, that you did all your homework, with your subs:D
Many thanx to you and to all the others on this forum that made it easy to do the homework. I’m happy to be able to make a small contribution to this forum and I hope my curves are of some interest for the general forum community.
I have tried turning the subs to the right and left, facing each other and facing outwards. The frequency response is however very similar to having both subs facing the MLP, so no drastic chances there.

Question:
I usually measure the frequency response with only the center channel and both subs.
What are your suggestion regarding measurement with REW?
Center speaker plus subs or
Left and Right speaker plus subs

I do run my center channel hot to better hear the dialog as you can see in my attachment (Cent vs L+R.png).
It is interesting to see the difference in frequency response when doing measurements with different front speakers.


Best regards,

//Peter

PS;
I attach a picture (Mic placement.png) where I moved the UMIK mic an inch up and to the right.
These things are sensitive...
 

Attachments

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Discussion Starter #719 (Edited)
Many thanx to you and to all the others on this forum that made it easy to do the homework. I’m happy to be able to make a small contribution to this forum and I hope my curves are of some interest for the general forum community.
I have tried turning the subs to the right and left, facing each other and facing outwards. The frequency response is however very similar to having both subs facing the MLP, so no drastic chances there.

Question:
I usually measure the frequency response with only the center channel and both subs.
What are your suggestion regarding measurement with REW?
Center speaker plus subs or
Left and Right speaker plus subs

I do run my center channel hot to better hear the dialog as you can see in my attachment. It is interesting to see the difference in frequency response when doing measurements with different front speakers.

Best regards,

//Peter

Hi Peter,

Most people either measure with the CC and the subs for primarily movie watching, or with the front speakers and the subs for primarily music listening. In either case, the goal is to optimize the crossover from the speaker(s) to the subwoofers by adjusting distance or phase, or by physically moving the subs. You wouldn't be able to change the frequency response in any global sense, in any event, no matter which speakers you measured with. Once you play all of the speakers together, at the same time, the sum of the whole is usually better than the sum of the individual parts, as the speakers support each other, and as the sounds blend together. So, I'm not sure which speakers you measure with to do your tweaking will really make a major difference.

I can see that you have your center channel boosted quite a bit, relative to the front speakers. You mentioned earlier that you believed that you had tried what is known as cascading crossovers. That technique definitely makes dialogue more intelligible to some people, so that might be something to experiment with some more. Unfortunately, though, I think that with 100Hz crossovers there may be a limit to what you can do to keep bass frequencies out of your center channel.

I would definitely try turning DEQ off, though, if you are currently using it, as that is boosting the bass in all of the channels, including the CC. If you do that, you will probably need to add more independent subwoofer boost, but you can limit how high in the frequency range the subwoofers play.

We all hear differently, so bass frequencies in your CC may not be affecting what you hear. But, in my case, the more that I can keep bass frequencies from artificially coloring voices, the more that I can hear clearer articulation. Implementing cascading crossovers definitely helps with that in my situation. But, that is a YMMV issue, and again, if you can't go down to 80Hz (or maybe even 90Hz) crossovers, the effect may not be sufficiently pronounced to be noticeable.

You may already know this, but I should also note that what measures best may not always sound best. So, I would also bear that in mind when experimenting with crossovers. I'm thinking of trying cascading crossovers, with everything set to 90Hz, in this case.

I suspect that part of the problem with dialogue, though, may be due to the fact that your wall-mounted center channel speaker can't point exactly at your listening position. Some frequencies are very directional, and that is especially true with hearing consonants well in the human voice. I find that if someone turns his head away from us just slightly, we can have much greater difficulty in understanding what he/she says, as opposed to when that person is addressing us directly. More volume definitely helps with that, but directionality is also very important.

Long-term, perhaps it would be possible to get a larger CC that could be pointed more directly at your listening position and your head height. The CC is in many ways the most important speaker in an HT system. It certainly is for movies. :)

Regards,
Mike
 

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Registered
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Hi,

You are very welcome! I hope that the Guide is helpful, and that the thread is a good place to talk about anything audio-related.

I think that you are just going to have to experiment to determine what subwoofer arrangement works best. But, I will make some observations. First, it sounds as if you have a very nice HT, and four FV15's should be giving you some good bass. I would not personally choose to stack ported subwoofers, in pairs like that. Instead, I would spread them out around the room. So, my first test arrangement would be to put one sub in each of the four corners of the room. And, my second would be to test four 1/4 wall locations.

Spreading the subs out that way, on multiple walls, will engage more room modes and should result in a more uniform frequency response throughout the room. If, in the process, you get rid of some dips in the FR, you may find that you don't need quite as much bass boost to enjoy the same master volume levels.

You didn't mention your typical listening levels or how much subwoofer boost you are adding post-calibration. When you put one pair of subs in the rear of the room, you may find that you need to reverse the phase on those two rear subwoofers by up to 180 degrees in order to avoid some cancellation. That is part of the trial-and-error process of repositioning the subs.

You can certainly try putting all four subwoofers behind you. The advantage of doing that is that you would be much closer to your subs, and you shouldn't need as much subwoofer volume to hear the same amount of bass. But, you will lose the advantage of potentially improving the FR, so that's just something to determine by listening, or by measuring if you have REW.

The biggest disadvantage of having all four subwoofers toward the rear of the room (other than the probably less effective FR) would be some probable bass localization. I would definitely be able to localize the bass if all of my subs were somewhat behind me and a long way from the action occurring on the screen. But, this is something that you will have to test to determine whether this is something that you notice, and if so, whether it really annoys you. I have four large ported subwoofers, and spread around the room on separate walls, they give me a sensation of bass envelopment that is very appealing. But, that's a YMMV situation as to what we notice, and what we like.

Frankly, my hope in this situation would be that moving two of the subwoofers closer to you will enable you to experience the same good bass sounds and sensations at a slightly lower volume. And, that the combination of lower bass volume, and greater distance (from your neighbors house) for two of the subwoofers will be just enough to satisfy him. If not, then you may, in fact, have to move all of the subwoofers closer to your listening position.

Even if you do get to that point, though, I would still probably try to spread the subwoofers out on three of the walls. And, there would be multiple combinations you could try. For instance, you could try 1/2 wall on the two side walls; and corners, or 1/4 wall, on the back wall. Or, you could try 1/4 walls on all three walls, with the front two near the front wall, but not actually on that wall that faces your neighbor. Stacking the subs anywhere would probably be my last resort, but who knows? That could conceivably be the best final arrangement. That's the trial-and-error aspect of this.

I see this as an equation with multiple variables. There is how much vibration your neighbor perceives; there is how much bass you perceive; there is whether you have an audibly or measurably decent FR, without a lot of random peaks and dips in bass volume; and there is whether the bass can be localized, and whether or not enough of it seems to come from the front sound stage to adequately support the movie?

I will be very interested to hear what you discover, so please come back to let us all know. And, if you can get close on the issue of localization, with 1/4 or 1/2 side walls, for instance, there are a couple of things you could try in order to reduce the localization effect a little more. Keep me posted!

Regards,
Mike


Thanks so much for the detailed response, mike, it is greatly appreciated.
I’m going to take a day and move the subs all over the place and experiment with all the possible locations you mentioned. I am definitely interested in a 3 wall placement for a better FR and immersive bass. I’ll report back with my findings, it may help someone in a similar situation down the road.
I forgot to mention in my earlier post that my normal listening volume is between -3 to -10 and I run my subs 3 dB hot. I use a denon x4300h (7.4.4)

Thanks again,




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