Jump to content

Recommended Posts

Hi all

 

I've slowly been converting an existing room in our house into a home theatre/media room and I'm now looking to head down the path of some acoustic treatment etc to optimise the room I have. You will see from the photos that there are some unusual design features but I'm keen to hear advice on how I can get the best out of my room. The room is approx 7 (D) x 5 (W) x 2.4m (H). Hidden behind the curtains are a large window on the left, french doors behind the screen and then a small home office room/area off to the right of the screen with a small window. There are also two boxed ceiling beams above splitting the main room into thirds.

 

The setup performs very well but I do sometimes feel that movies don't have the impact I would have expected for such a large and capable 7.1.4 setup. It's not a matter of amp power or volume but rather the impact of the sound. The Anthem amp and SVS sub can really crank up but sometimes I'm expecting a scene to blow me away but it just doesn't quite get there. Thus I'm after any advice from experienced members on what I should be investigating to move my room/setup to the next level.

 

Here is the frequency response from my Anthem ARC Genesis calibration when I setup the 7.1.4. From my untrained eye it looks like the 50-200Hz bass area is lacking the most and there are other issues in the 5-10k Hz area.

 

38983250_AnthemARC2.JPG.bc374e346a80dfb773baf51349e41df5.JPG

 

661060936_AnthemARC3.JPG.c52db844ee183ed474ef205fc6902cf0.JPG

 

Here's some photos of my current room setup to give you an idea:

IMG_6176.JPG.a9ad187962a44fe9d100816adf5944f3.JPG

 

IMG_6177.JPG.98ac6aea5cf3ad3ba983208c736240dc.JPG

 

IMG_6183.JPG.b9779d01dc47eeec554aa7ab9c29cdc8.JPG

 

IMG_6179.JPG.d157e62afe7afb46a7a104e167f94b4f.JPG

 

IMG_6178.JPG.7e467d39995fec330806dad1c32d28af.JPG

 

IMG_6180.JPG.a8331c7bf22fa8832fc75122651de07e.JPG

 

IMG_6182.JPG.8520c75e1e5fd85ecaeb817f8c46be1d.JPG

 

IMG_6174.JPG.25c2b3aa6629911a497322b9366ada18.JPG

 

IMG_6175.JPG.d3e61aba1ea676bccb794581e7e10b16.JPG

 

Some questions I have based on basic reading/tutorials etc I've perused:

- Is there a minimum distance my centre speaker should be away from my AT screen? I watched one Home Theatre Engineering youtube video which suggested minimum 30cm. Mine is about 5cm at present.

- We're running carpet tiles layed directly onto our concrete slab. The room isn't anywhere near as echoey as I would have expected but I'm wondering whether a large rug in the front third of the room may still help? I was thinking of a black one to better frame the screen and improve the contrast.

-  Do too many curtains reduce acoustic performance? Approx 40% of our wall space is draped in blockout curtains currently. This is somewhat of a necessity given our window on the left, french doors at the back and then office room to the right. I was also getting a lot of projector light bleeding through the AT screen onto the white wall behind when I didn't have the screen wall fully covered by curtains.

- How much acoustic impact is the office room area to the right, two boxed beams on the ceiling, windows and french doors and the storage cupboard in the back of the room likely to have?

- Any initial thoughts on whether I could benefit from bass traps, absorbers, skyline diffusers etc? I've just started reading about REW (Room EQ Wizard) and how to measure room frequency response etc. I gather this may give me some idea about what type of treatment to target and where?

 

Any advice appreciated. :) 

  • Like 1
  • Love 1
Link to post
Share on other sites
  • Replies 60
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Hi all   I've slowly been converting an existing room in our house into a home theatre/media room and I'm now looking to head down the path of some acoustic treatment etc to optimise the roo

Not necessarily, but conventional wisdom says that a crossover point of 250Hz is much too high. A mono subwoofer is meant to be an omni-directional bass source.   You could try this as

Absorption works best at wavelength/4 from the boundary...ie highest velocity Generally the bigger the air gap the better absorption up to wavelength/4   Lets take an absorption trap yo

i will guess your sub is the "old" pb2000? if so they are known for quite average mid bass performance, this seems to have been rectified in the pb1000/2000 pro series.

 

for that size room you want 2 subs anyway, so look at getting a 2000 pro or imo add a bigger sub. a pb3000 is the correct step up or a 2nd hand pb13 ultra. the 3000 series is only just behind the 4000 which supposedly replaced the 13 ultra so not worth paying the 4000 premium. (based on my readings on avs forums anyway.)

 

unfortunately we dont get access to the sub choices they do in the U.S. where none of the above would be considered adequate.

 

 

  • Like 1
Link to post
Share on other sites

I would expect you could do better than what you describe with the equipment you have. Do you have a measurement of all channels or at least front channels +sub at once? Also your target curve looks like it is flat. That will result in a forward sound with less bass.  Commonly used room curves  tend to tilt down from the bottom end to the top with around 5-10db difference depending on your room and taste.  Here is one of many things on the internet about customising a house curve to your preference. https://www.minidsp.com/forum/dirac-series-support/17523-advice-on-better-house-curve.

  • Like 1
Link to post
Share on other sites

Did you calibrate the volume for your various speakers to be 75 dB (C weighted, slow) before taking that measurement? It doesn't look like it to me.

 

ARC is very fussy in terms of you preparing the system for it to work its best. You need to get all channels at 75 dB at your primary listening position, with adjustments made if you have multiple subs. Refer

 

Quote

A Final Check and Rough Level Set

After you have confirmed all is well, you should do a rough level set so the Anthem Room Correction software will operate properly.  The idea is to get each speaker to roughly 75dB on your SPL meter or app. Just go through each one and adjust the volume up/down until you get them all around 75 dB.  If you have two subwoofers, turn one off and set it to 71 dB, then turn the other on and set it to the same. For four subwoofers, set each one to 67 dB. You may have to use the volume control on the back of your subwoofer to reach the correct setting.  

 

You might find you get a better result using REW for measurement of your room. I have found ARC pretty ordinary in terms of detail. It doesn't tell you anything about anything other than frequency response (no waterfalls, no timing, no decay / reverb measurements). 

Link to post
Share on other sites

A black rug will look nice but I don't think it will improve sound impact.

 

How far are you sitting from the Left, Center and Right speakers?

Consider moving the main lounge forward especially if you're more than 3 metres away from the Left and Right speakers.

If you were to change/upgrade speakers I would concentrate on the Left, Right and Centre.

 

You could probably do more regarding subwooferage.

Link to post
Share on other sites

A dip around 50 to 200Hz will definitely sound boring. What you want to find out is whether the ARC software put that dip in, which can be fixed, or whether it's the room, which probably needs a lot of bass trapping to fix.

Link to post
Share on other sites
23 minutes ago, Pim said:

A dip around 50 to 200Hz will definitely sound boring. What you want to find out is whether the ARC software put that dip in, which can be fixed, or whether it's the room, which probably needs a lot of bass trapping to fix.

 

According to the screen-shots as per below ARC should be greatly improving those dips as shown in green (Calculated).

The sub-woofer looks to be taking over from about 60-80Hz down to 20Hz.

 

38983250_AnthemARC2.JPG.bc374e346a80dfb773baf51349e41df5.JPG

 

661060936_AnthemARC3.JPG.c52db844ee183ed474ef205fc6902cf0.JPG

Link to post
Share on other sites

@OzJustinthat's a really cool projector screen! Can you tell me the brand and model?

It's possible that room to the side with the rack is creating an echo chamber which would cause some issues.

 

Link to post
Share on other sites
13 hours ago, hopefullguy said:

i will guess your sub is the "old" pb2000? if so they are known for quite average mid bass performance, this seems to have been rectified in the pb1000/2000 pro series.

 

for that size room you want 2 subs anyway, so look at getting a 2000 pro or imo add a bigger sub. a pb3000 is the correct step up or a 2nd hand pb13 ultra. the 3000 series is only just behind the 4000 which supposedly replaced the 13 ultra so not worth paying the 4000 premium. (based on my readings on avs forums anyway.)

 

unfortunately we dont get access to the sub choices they do in the U.S. where none of the above would be considered adequate.

 

 

Yes running the "old" PB2000 (non-Pro) model. I certainly don't consider it old though and it has served me very well. It's interesting to hear about the supposed mid bass performance. I would consider moving to a larger or dual sub setup at a later date but really looking to optimise my current setup first. Here are my current Anthem > Bass Management settings. The Atmos speakers do seem to have a strange crossover point at 80Hz. I would think they should be more like 250Hz to match the centre speaker. My other floorstanders can handle bass well below 100Hz.

919077070_Image1.thumb.jpg.7339b11902c2dde9d918005ab1e3f8bc.jpg

12 hours ago, frednork said:

I would expect you could do better than what you describe with the equipment you have. Do you have a measurement of all channels or at least front channels +sub at once? Also your target curve looks like it is flat. That will result in a forward sound with less bass.  Commonly used room curves  tend to tilt down from the bottom end to the top with around 5-10db difference depending on your room and taste.  Here is one of many things on the internet about customising a house curve to your preference. https://www.minidsp.com/forum/dirac-series-support/17523-advice-on-better-house-curve.

I only have measurements as provided by the ARC calibration. Do you think I should learn to use REW to measure manually?

The Anthem target curves (blue line) do look pretty flat for the non-sub channels from about 100Hz. That article you linked seems to suggest some tweaks to the target curve so it isn't as close to flat.

11 hours ago, BugPowderDust said:

Did you calibrate the volume for your various speakers to be 75 dB (C weighted, slow) before taking that measurement? It doesn't look like it to me.

 

ARC is very fussy in terms of you preparing the system for it to work its best. You need to get all channels at 75 dB at your primary listening position, with adjustments made if you have multiple subs. Refer

 

 

You might find you get a better result using REW for measurement of your room. I have found ARC pretty ordinary in terms of detail. It doesn't tell you anything about anything other than frequency response (no waterfalls, no timing, no decay / reverb measurements). 

I didn't calibrate to 75dB before I ran ARC. Is that done through the level calibration field by boosting the dB to each channel and measuring with a mic until each channel hits approx 75dB max?

Here are my current Anthem > Level Calibration settings:

1692530179_Image2.thumb.jpg.082a6c8054291859a37d6845af80411d.jpg

967233888_Image3.thumb.jpg.823b5d87ab46063dfb38e70ae0561719.jpg

6 hours ago, Satanica said:

A black rug will look nice but I don't think it will improve sound impact.

 

How far are you sitting from the Left, Center and Right speakers?

Consider moving the main lounge forward especially if you're more than 3 metres away from the Left and Right speakers.

If you were to change/upgrade speakers I would concentrate on the Left, Right and Centre.

 

You could probably do more regarding subwooferage.

Primary listening position is approx 4-5m back from the LCR channels. I am running a 140" screen though so have set my seating distances based on that. 3m from the screen would likely be too close for my current setup/room.

4 hours ago, Pim said:

A dip around 50 to 200Hz will definitely sound boring. What you want to find out is whether the ARC software put that dip in, which can be fixed, or whether it's the room, which probably needs a lot of bass trapping to fix.

I assume I determine that by running some measurements with REW or similar? I'll need to learn how to use it. Do you know if I can use my Anthem mic with REW?

3 hours ago, Satanica said:

 

According to the screen-shots as per below ARC should be greatly improving those dips as shown in green (Calculated).

The sub-woofer looks to be taking over from about 60-80Hz down to 20Hz.

 

38983250_AnthemARC2.JPG.bc374e346a80dfb773baf51349e41df5.JPG

 

661060936_AnthemARC3.JPG.c52db844ee183ed474ef205fc6902cf0.JPG

Yes my reading of the graphs is that ARC is improving the bass. See my above screenshot of my current bass management settings. Low pass filter for LFE is set to 120Hz and crossover points are 80-250Hz depending on speaker. My floorstanders are capable of hitting below 30Hz from memory but it does look strange that the crossover point for my small Krix Helix Atmos speakers is set to 80Hz.

 

Apologies but I think I uploaded my old ARC 7.1 speaker profile. Attached is my current 7.1.4 ARC summary.

ARC Genesis Results 7.1.4 MRX1120 250121 V2.pdf

 

31 minutes ago, Xecuter said:

@OzJustinthat's a really cool projector screen! Can you tell me the brand and model?

It's possible that room to the side with the rack is creating an echo chamber which would cause some issues.

 

I'm running a custom screen using an LP Morgan 140" frame with OzTheatre AcousticVision 4K fabric all bolted to a custom metal frame on wheels. Further pics and details are in my build thread here: 

 

  • Like 1
Link to post
Share on other sites
5 minutes ago, OzJustin said:

I only have measurements as provided by the ARC calibration. Do you think I should learn to use REW to measure manually?

The Anthem target curves (blue line) do look pretty flat for the non-sub channels from about 100Hz. That article you linked seems to suggest some tweaks to the target curve so it isn't as close to flat.

I dont use Anthem so not sure how much you can customise but if you can create a similar curve to one of those in the article I linked and get ARC to match it it may be enough to get you where you want to be. If not then may be worth going to REW

Link to post
Share on other sites

Having speakers in the corners of the room is a NO, NO,  Your bass becomes "boomy" with peaks in the bass region, as shown by your measurements.  You need to move those speakers out of the corners as much as possible.  Yes, I realise you have limited space.  Suggest moving the second row away from the wall (otherwise people seated here will not get a good experience) and bring the rear speakers forward (but behind second row).  Make the speaker distance to the rear wall more than the side wall.  Even moving 0.5m will help.   Similarly for front speakers.  The intent is to reduce the bass peaks in the measurements.

 

Do you have freedom to move the sub?  Using ARC Quick Measure, you can move the sub to maybe find a spot where the bass has the least dip.  Ideally get a second sub.

 

After you have improved the speaker and sub positions, ARC has many things that you can do to tweak things.

https://www.anthemarc.com/arc-genesis/advanced-settings/index.php

 

Suggest not going into REW, which is a lot more complicated and does require effort to learn and master.  And you will need a new USB microphone because the Anthem microphone works only with ARC. 

  • Like 1
Link to post
Share on other sites

7 hours ago, Snoopy8 said:

Having speakers in the corners of the room is a NO, NO,  Your bass becomes "boomy" with peaks in the bass region, as shown by your measurements.  You need to move those speakers out of the corners as much as possible.  Yes, I realise you have limited space.  Suggest moving the second row away from the wall (otherwise people seated here will not get a good experience) and bring the rear speakers forward (but behind second row).  Make the speaker distance to the rear wall more than the side wall.  Even moving 0.5m will help.   Similarly for front speakers.  The intent is to reduce the bass peaks in the measurements.

 

Do you have freedom to move the sub?  Using ARC Quick Measure, you can move the sub to maybe find a spot where the bass has the least dip.  Ideally get a second sub.

 

After you have improved the speaker and sub positions, ARC has many things that you can do to tweak things.

https://www.anthemarc.com/arc-genesis/advanced-settings/index.php

 

Suggest not going into REW, which is a lot more complicated and does require effort to learn and master.  And you will need a new USB microphone because the Anthem microphone works only with ARC. 

Thanks for the suggestions Snoopy.

Does my speaker to wall positioning matter as much when the speaker ports are front facing? I have no rear ports in my surround or rear speakers. I could move them forward maybe 30cm but any more than that and they will start to severely block the cupboard and rear entrance door. 
 

My front left and right speakers have front and rear ports. I have a bit more flexibility there and could move them forward 30-50cm if it will improve performance. Will it matter if the centre speaker is then not lined up with the other fronts?

 

I wouldn’t worry about the seating performance of the rear lounge. It’s more a storage space for it and will likely only be used 5% of the time. In those cases I would move it forward much closer to the other lounge. I’m really only optimising the room for the main 4 seats.

 

Re the sub - If I move my screen forward approx 30cm then I could probably fit the sub either side of the centre channel (and have space to install a second, or larger single sub down the track). I know my currently positioning is odd but it was one of 3 desirable locations I identified when I performed the ‘subwoofer crawl’ and it gives me easy access to hidden power. Do you think it’s sub positioning, EQ or bass traps (or a combination) that’s needed?

Link to post
Share on other sites
10 hours ago, OzJustin said:

 

Primary listening position is approx 4-5m back from the LCR channels. I am running a 140" screen though so have set my seating distances based on that. 3m from the screen would likely be too close for my current setup/room.

 

I sit 3.2m away from my 165" 2.35:1 screen and it is just about perfect - a lot of people on AVSForum.com are reporting similar seating distances and some are even closer. 

Try moving your seat to between 33-38% of room length (for best acoustics) from back wall and then move your screen to where you like it best. 

Link to post
Share on other sites
1 hour ago, OzJustin said:

Does my speaker to wall positioning matter as much when the speaker ports are front facing? I have no rear ports in my surround or rear speakers. I could move them forward maybe 30cm but any more than that and they will start to severely block the cupboard and rear entrance door. 
 

My front left and right speakers have front and rear ports. I have a bit more flexibility there and could move them forward 30-50cm if it will improve performance. Will it matter if the centre speaker is then not lined up with the other fronts?

Moving them 30 cm away from the back wall will help; I do understand there is only so much that you can move.  Corners reinforce bass regardless of whether there are rear ports.  As a learning exercise, move your speakers temporarily further away from the walls and you should see the bass peaks drop in the ARC measurements.  You may also see the bass dips change.

 

The centre speaker does not need to line up with the other fronts.  Just ensure you adjust the speaker distance when you move them permanently.

 

1 hour ago, OzJustin said:

Re the sub - If I move my screen forward approx 30cm then I could probably fit the sub either side of the centre channel (and have space to install a second, or larger single sub down the track). I know my currently positioning is odd but it was one of 3 desirable locations I identified when I performed the ‘subwoofer crawl’ and it gives me easy access to hidden power. Do you think it’s sub positioning, EQ or bass traps (or a combination) that’s needed?

Again, experiment with different sub positions and use ARC Quick Measure to see the impact on the subs, as well as the rest of the speakers.  Suggest you try moving speakers and sub first and learn more about the room using ARC measurements.  You can then consider bass traps, which have to be big to be effective, and you will not be able to put them at the rear.  

 

If you can afford a second sub, that will improve things, and you can use ARC to integrate the subs

https://www.pooraudiophile.com/2014/06/how-to-calibrate-dual-subwoofers-with.html

 

ARC will do the EQ for you, and there are still ARC tweaks you can do to improve things.  But do that after...

Link to post
Share on other sites

Which movies scenes do you feel are lacking?

 

I'm in Brisbane and could probably help you get REW up and running if you want to go for it (I definitely recommend this!) The graphs provided by Anthem are only "calculated" ,correct? This means the "actual" measured response from your MLP may be different.

 

If I had to take a guess, I'd say the major issues are:

 

1. Your Native,unEQ'd sub response is poor,ARC may be using up all your available headroom trying to flatten it. A single PB-2000 in that size room may struggle at the best of times (depending on how loud you listen of course)

There is an option in ARC to run sweeps on repeat,with measurements, to assist finding the best place for the sub (shown below)

 

 

 

2. In HT the Center channel handles 80%+ of everything going on, having the crossover so high at 250Hz, well into the range where bass is localizable, and with the subwoofer so far away from it,I'm surprised it doesn't sound "disjointed" or boomy. If you have to have it crossed at 250Hz,I'd move the sub closer to the front stage,or lower the Center crossover to 80-100Hz

Edited by jamiebosco
  • Like 2
Link to post
Share on other sites

I was going to ask why the centre speaker is crossing over at 250 hz, and not similar to the front left and front right at around 100 hz.  80 hz would be a great number, but 100 hz is fine.

 

250 hz implies a very small satellite single-cone speaker, not a 2-way.

Any ideas why Anthem is seeing such poor response from your centre speaker?

 

Benje

 

PS  looking at your projector screens.  Are they acoustically transparent?  The centre speaker seems to be behind them.  Perhaps they aren't acoustically transparent?

Edited by Benje
extra question
Link to post
Share on other sites

Also, seeing your Center is behind the screen,have you tried running it in the vertical orientation? These types of speakers almost always have better off-axis measurements run vertically , they measure fine horizontally up to around 15 deg. off-axis, so the main seats should be fine as it currently is. just something to think about

Link to post
Share on other sites

You'd want the front face of the speakers at 900mm to 1200mm from the wall as a quick guess to drop the boomy mess. You are driving modes giving boom and loss of clarity and orientation. 

 

I'd pull your fronts out a whole lot more than that, and the recess to the right of your right front isn't helping. No reason for them to be flush with the screen.

 

Spikes at 50Hz and 80Hz are room modes. The dips are probably between resonances. The speakers close to the walls give maximum coupling to the modes. You want to avoid that. I spent a couple of hours dialing in speaker and listening position by ear in 100mm steps for stereo. You've got 12 speakers. 

Edited by DrSK
Link to post
Share on other sites

I suspect the screen may be causing the centre speaker problems and thus setting such a large crossover?  This can need changed easily within ARC.

 

I have seen ARC set some larger cross over settings, but it appears to not affect the sound!  Did not hear a difference when I changed it manually within ARC.

 

But aren't we getting ahead of ourselves by focusing on what ARC can or cannot do?  OP has issues caused by speaker & sub placements and perhaps the screen. If these are not resolved first, then no amount of room correction can fix a problem room....

Link to post
Share on other sites

An AT screen usually attenuates the treble range normally though right? Not under 300Hz which is more midbass/midrange

Link to post
Share on other sites

a bunch of good ideas above

10 hours ago, jamiebosco said:

Also, seeing your Center is behind the screen,have you tried running it in the vertical orientation? These types of speakers almost always have better off-axis measurements run vertically , they measure fine horizontally up to around 15 deg. off-axis, so the main seats should be fine as it currently is. just something to think about

You want the sound from your centre channel to be identical in character to your left/right mains - lots of people use an identical speaker...and it should be oriented the same way as your mains so the dispersion pattern is the same, with the tweeters at the same height across left/centre/right, so panning vocals don't change height from one side to the other.

For the same reasons you want the crossover point to your sub set identically across left/centre/right speakers.

 

As mentioned above, the graph for your sub makes it look like the crossover is set too high - 80Hz should be fine with your mains.

 

As also said above, another sub may help - but you can do that later...

 

9 hours ago, DrSK said:

and the recess to the right of your right front isn't helping.

IMHO, that recess is screaming out for a nice fat absorption trap on wheels closing off the alcove - just like the wheel mounted screen...I suggested this in a different thread.

 

If you built a frame on wheels the width/height of that gap, that you just roll aside to get access to the alcove, you could achieve "proper bass trap" performance with absorption.

I would recommend using fluffy polyester insulation like this:

https://enviroflex.com.au/shop/product/greenstuf-polyester-ceiling-insulation-batts/?attribute_r-value=R4.0&attribute_width=430mm&keyword=&campaignID=10346161588&matchtype=&adgroupID=103357098216&gclid=Cj0KCQjwlMaGBhD3ARIsAPvWd6jn92_JQ8A9THeLdhBV9LrXWTW74u6IQ6nL1kSXZubAAQWiJMneONUaAhYIEALw_wcB

 

They come in 2 widths to fit between standard joist spacing, 430mm or 580mm

My suggestion would be to lay them flat and stack them across the entire width/height of the alcove entrance - so your movable trap is either 430mm deep or 580mm deep.

Either would provide "bass trapping" much lower than absorption is usually capable of, because of the large air gap behind - the alcove.

You'd need a bunch of bags, but @ $43 a bag for the 580mm wide batts it's not an expensive experiment...and cheaper for the 430mm wide batts ($32/bag).

 

cheers,

Mike

Edited by almikel
typo
  • Like 1
Link to post
Share on other sites
22 hours ago, niterida said:

I sit 3.2m away from my 165" 2.35:1 screen and it is just about perfect - a lot of people on AVSForum.com are reporting similar seating distances and some are even closer. 

Try moving your seat to between 33-38% of room length (for best acoustics) from back wall and then move your screen to where you like it best. 

Ok I'm pretty sure I'm roughly at that 30-40% percentage already for room seating but can move my screen forward 50cm or so.

21 hours ago, Snoopy8 said:

Moving them 30 cm away from the back wall will help; I do understand there is only so much that you can move.  Corners reinforce bass regardless of whether there are rear ports.  As a learning exercise, move your speakers temporarily further away from the walls and you should see the bass peaks drop in the ARC measurements.  You may also see the bass dips change.

 

The centre speaker does not need to line up with the other fronts.  Just ensure you adjust the speaker distance when you move them permanently.

 

Again, experiment with different sub positions and use ARC Quick Measure to see the impact on the subs, as well as the rest of the speakers.  Suggest you try moving speakers and sub first and learn more about the room using ARC measurements.  You can then consider bass traps, which have to be big to be effective, and you will not be able to put them at the rear.  

 

If you can afford a second sub, that will improve things, and you can use ARC to integrate the subs

https://www.pooraudiophile.com/2014/06/how-to-calibrate-dual-subwoofers-with.html

 

ARC will do the EQ for you, and there are still ARC tweaks you can do to improve things.  But do that after...

Ok that's good to know that the centre speaker doesn't need to line up.

How do you think a pair of SVS PB-1000 Pro subs at the front of the room behind my screen would perform compared to my existing single SVS PB-2000?

18 hours ago, jamiebosco said:

Which movies scenes do you feel are lacking?

 

I'm in Brisbane and could probably help you get REW up and running if you want to go for it (I definitely recommend this!) The graphs provided by Anthem are only "calculated" ,correct? This means the "actual" measured response from your MLP may be different.

 

If I had to take a guess, I'd say the major issues are:

 

1. Your Native,unEQ'd sub response is poor,ARC may be using up all your available headroom trying to flatten it. A single PB-2000 in that size room may struggle at the best of times (depending on how loud you listen of course)

There is an option in ARC to run sweeps on repeat,with measurements, to assist finding the best place for the sub (shown below)

 

 

 

2. In HT the Center channel handles 80%+ of everything going on, having the crossover so high at 250Hz, well into the range where bass is localizable, and with the subwoofer so far away from it,I'm surprised it doesn't sound "disjointed" or boomy. If you have to have it crossed at 250Hz,I'd move the sub closer to the front stage,or lower the Center crossover to 80-100Hz

One movie that comes to mind is John Wick 3. The gun fights just didn't seem to have the punch I would expect. Conversely Sicario had amazing gun fights (you actually felt like you were in the middle of each bullet flying past) - in both cases these were run off a 4K disc on my Panasonic player, but perhaps the mix is partially to blame.

I might take you up on that offer. It sounds like calibration rather than acoustic treatment could be part of my existing problem.

17 hours ago, Benje said:

I was going to ask why the centre speaker is crossing over at 250 hz, and not similar to the front left and front right at around 100 hz.  80 hz would be a great number, but 100 hz is fine.

 

250 hz implies a very small satellite single-cone speaker, not a 2-way.

Any ideas why Anthem is seeing such poor response from your centre speaker?

 

Benje

 

PS  looking at your projector screens.  Are they acoustically transparent?  The centre speaker seems to be behind them.  Perhaps they aren't acoustically transparent?

My centre speaker is a VAF DC-6 speaker which is comparatively small against all of my large floorstanders. I can look at reducing the crossover closer to 100Hz but won't that then expand the centre to play up to 100Hz (more bass oriented) which won't be its strength?

17 hours ago, jamiebosco said:

Also, seeing your Center is behind the screen,have you tried running it in the vertical orientation? These types of speakers almost always have better off-axis measurements run vertically , they measure fine horizontally up to around 15 deg. off-axis, so the main seats should be fine as it currently is. just something to think about

I haven't tried vertical orientation. Would that suit a VAF DC-6 design?

16 hours ago, DrSK said:

You'd want the front face of the speakers at 900mm to 1200mm from the wall as a quick guess to drop the boomy mess. You are driving modes giving boom and loss of clarity and orientation. 

 

I'd pull your fronts out a whole lot more than that, and the recess to the right of your right front isn't helping. No reason for them to be flush with the screen.

 

Spikes at 50Hz and 80Hz are room modes. The dips are probably between resonances. The speakers close to the walls give maximum coupling to the modes. You want to avoid that. I spent a couple of hours dialing in speaker and listening position by ear in 100mm steps for stereo. You've got 12 speakers. 

Ok sounds like calibration and speaker placement could help. Will investigate this weekend.

16 hours ago, Snoopy8 said:

I suspect the screen may be causing the centre speaker problems and thus setting such a large crossover?  This can need changed easily within ARC.

 

I have seen ARC set some larger cross over settings, but it appears to not affect the sound!  Did not hear a difference when I changed it manually within ARC.

 

But aren't we getting ahead of ourselves by focusing on what ARC can or cannot do?  OP has issues caused by speaker & sub placements and perhaps the screen. If these are not resolved first, then no amount of room correction can fix a problem room....

Good point Snoopy. I want to focus on optimising the setup. :) 

12 hours ago, jamiebosco said:

An AT screen usually attenuates the treble range normally though right? Not under 300Hz which is more midbass/midrange

To confirm, I am running a high quality AT screen.

Link to post
Share on other sites
7 hours ago, almikel said:

a bunch of good ideas above

You want the sound from your centre channel to be identical in character to your left/right mains - lots of people use an identical speaker...and it should be oriented the same way as your mains so the dispersion pattern is the same, with the tweeters at the same height across left/centre/right, so panning vocals don't change height from one side to the other.

For the same reasons you want the crossover point to your sub set identically across left/centre/right speakers.

 

As mentioned above, the graph for your sub makes it look like the crossover is set too high - 80Hz should be fine with your mains.

 

As also said above, another sub may help - but you can do that later...

 

IMHO, that recess is screaming out for a nice fat absorption trap on wheels closing off the alcove - just like the wheel mounted screen...I suggested this in a different thread.

 

If you built a frame on wheels the width/height of that gap, that you just roll aside to get access to the alcove, you could achieve "proper bass trap" performance with absorption.

I would recommend using fluffy polyester insulation like this:

https://enviroflex.com.au/shop/product/greenstuf-polyester-ceiling-insulation-batts/?attribute_r-value=R4.0&attribute_width=430mm&keyword=&campaignID=10346161588&matchtype=&adgroupID=103357098216&gclid=Cj0KCQjwlMaGBhD3ARIsAPvWd6jn92_JQ8A9THeLdhBV9LrXWTW74u6IQ6nL1kSXZubAAQWiJMneONUaAhYIEALw_wcB

 

They come in 2 widths to fit between standard joist spacing, 430mm or 580mm

My suggestion would be to lay them flat and stack them across the entire width/height of the alcove entrance - so your movable trap is either 430mm deep or 580mm deep.

Either would provide "bass trapping" much lower than absorption is usually capable of, because of the large air gap behind - the alcove.

You'd need a bunch of bags, but @ $43 a bag for the 580mm wide batts it's not an expensive experiment...and cheaper for the 430mm wide batts ($32/bag).

 

cheers,

Mike

Good suggestions thanks Mike.

Do I really want the same crossover point for LCR even when the left and right speakers are far more capable in the lower Hz? I can try standing up my centre speaker to see if it changes the response. Perhaps I should be hunting for another VAF DC-X floorstander to replace the smaller existing centre. The DC-X have evolved over the years - early ones had a single tweeter and twin drivers, while later ones had twin side-by-side tweeters and twin drivers - not sure how important that is to match my left and right design?

 

Re the bass absorber panels - I gather they would still be effective with the curtain across the front? I may need to create two separate panels to allow regular access to the room (it’s my home office). I could just push one away for access. Is there an easy way to test this absorber theory before going through the effort? Borrow a friend’s absorber panels (obviously won’t be fully flush but I gather near airtight isn’t needed) and set them up across the alcove and measure response?

Link to post
Share on other sites
3 hours ago, OzJustin said:

Do I really want the same crossover point for LCR even when the left and right speakers are far more capable in the lower Hz?

 

Not necessarily, but conventional wisdom says that a crossover point of 250Hz is much too high.

A mono subwoofer is meant to be an omni-directional bass source.

 

You could try this as an experiment, turn your centre speaker off letting your left and right to take over centre channel duties.
Of course this is only optimal for the sweet spot.

Edited by Satanica
  • Like 2
Link to post
Share on other sites
4 hours ago, OzJustin said:

How do you think a pair of SVS PB-1000 Pro subs at the front of the room behind my screen would perform compared to my existing single SVS PB-2000?

 

You only live once (PowerSound Triax T-18).

 

https://www.deephzaudio.com/Power Sound Index Page.html

https://www.deephzaudio.com/Power Sound Triax T-18 product page.html

Edited by Satanica
  • Like 1
Link to post
Share on other sites
4 hours ago, OzJustin said:

How do you think a pair of SVS PB-1000 Pro subs at the front of the room behind my screen would perform compared to my existing single SVS PB-2000?

You can also add the PB-1000 to your existing PB-2000.  It does not have to be identical subs.  Some ideas for dual sub placements

https://www.aperionaudio.com/blogs/aperion-audio-blog/dual-subwoofer-placement-for-your-home

There is also a front and back location, but you have a sofa at the back.

 

The reason for using dual subs is to get as even a bass response as possible in the room.  Contrary to popular opinion, it is not how loud, but how even the bass is.   For reference only, I have taken it further than most people!

https://www.stereo.net.au/forums/topic/242166-using-multi-subs-mso-to-get-even-bass-in-room-across-sitting-positions/?do=findComment&comment=4739911&_rid=161413

 

4 hours ago, OzJustin said:

One movie that comes to mind is John Wick 3. The gun fights just didn't seem to have the punch I would expect. Conversely Sicario had amazing gun fights (you actually felt like you were in the middle of each bullet flying past) - in both cases these were run off a 4K disc on my Panasonic player, but perhaps the mix is partially to blame.

I might take you up on that offer. It sounds like calibration rather than acoustic treatment could be part of my existing problem.

It is clear that you have a bass problem in the room.  You can fix this by treating the room, but most people do not do it correctly and thoroughly.  This is because it is a hard problem to solve.  This is an old but still good guide

https://www.hifizine.com/2011/06/bass-integration-guide-part-1/

It will give you an idea oh how to do this properly, and some of the REW measurements to be done.

 

4 hours ago, OzJustin said:

I might take you up on that offer. It sounds like calibration rather than acoustic treatment could be part of my existing problem.

My centre speaker is a VAF DC-6 speaker which is comparatively small against all of my large floorstanders. I can look at reducing the crossover closer to 100Hz but won't that then expand the centre to play up to 100Hz (more bass oriented) which won't be its strength?

I haven't tried vertical orientation. Would that suit a VAF DC-6 design?

It looks like VAF DC-6 is a proper centre speaker.  I think a few people thought you were using a normal speaker sitting horizontally.

 

Not sure what your other speakers are, but ideally, get a centre speaker which is the same brand and series as your fronts.  Do not scrimp on the centre; it carries most of the dialogue and is as important, maybe more so, as the fronts.

 

4 hours ago, OzJustin said:

Good point Snoopy. I want to focus on optimising the setup. :)

Please do not forget to move your speakers away from the corners.  To give you a better picture of how corners affect the sound, please look at the second graph of this post  (my stereo speakers can compensate for corners).

https://www.stereo.net.au/forums/topic/342649-so-in-shared-rooms-why-choose-dsp-enabled-active-speakers/?_rid=161413

 

Once you have the speakers, subs, room treatment sorted out,  I can take you through some ARC advanced settings that can further improve the bass.  In the mean time, suggest not playing with ARC because you are changing lots of things.

 

4 hours ago, OzJustin said:

To confirm, I am running a high quality AT screen.

It may be high quality, but is it acoustically transparent ?  This is essential when you put speakers behind a screen.

Edited by Snoopy8
Typo
Link to post
Share on other sites

Oz Justin

 

lots of good advice from Snoopy8 above.

 

Re the acoustic transparent screen,

I wanted to make sure the screen wasn't affecting the centre speaker issues.

It may be fine.

Next time you are running ARC (noting Snoppy8's point about not changing too much), can you check the performance of the centre speaker with the screen and also with it wheeled away?

If the in-room response is the same, the issue is definitely not the screen.

I doubt that the dc-6 is the problem, unless there is a fault with it eg a damager speaker cone or cross-over.

 

If you do this, you could try moving the centre speaker a but lower, or a bit higher, or vertically rather than horizontally.

Of course, you might not see any variation.

 

Check how you can use ARC to test a single speaker's response.

 

Benje

  • Like 1
Link to post
Share on other sites
14 minutes ago, Benje said:

Re the acoustic transparent screen,

I wanted to make sure the screen wasn't affecting the centre speaker issues.

It may be fine.

Next time you are running ARC (noting Snoppy8's point about not changing too much), can you check the performance of the centre speaker with the screen and also with it wheeled away?

If the in-room response is the same, the issue is definitely not the screen.

I doubt that the dc-6 is the problem, unless there is a fault with it eg a damager speaker cone or cross-over.

 

If you do this, you could try moving the centre speaker a but lower, or a bit higher, or vertically rather than horizontally.

Of course, you might not see any variation.

 

Check how you can use ARC to test a single speaker's response.

Good points on testing the centre speaker.  To test a single speaker, use ARC Quick Measure.

Link to post
Share on other sites

Crossing your Centre to the sub(s) over as high as 250Hz can work IF the subs are situated very close to the speaker, but looking at the room there looks to be around 4m distance between the Centre speaker - this would have to be localizable, and must sound a bit "off" having some of the  vocal range/onscreen action coming from a source so far from the screen? 250Hz is also at the extreme  limits of where a PB-2000 can play, they drop off pretty hard after that

 

I would try moving the Sub underneath the table holding the centre speaker and rerun ARC and see how it sounds

 

 

If gunshots from the John Wick movies are lacking impact - there's definitely something wrong with the sub response or the integration between the speakers and sub at the crossover region

Edited by jamiebosco
Link to post
Share on other sites
11 hours ago, Satanica said:

That looks like a beast! Unfortunately I think it’s a bit beyond my budget.  How would one of those PSA subs compare to two or three separate subs in terms of frequency response and whole room balance? Is it the equivalent of three separate subs despite the single enclosure?

11 hours ago, Snoopy8 said:

You can also add the PB-1000 to your existing PB-2000.  It does not have to be identical subs.  Some ideas for dual sub placements

https://www.aperionaudio.com/blogs/aperion-audio-blog/dual-subwoofer-placement-for-your-home

There is also a front and back location, but you have a sofa at the back.

 

The reason for using dual subs is to get as even a bass response as possible in the room.  Contrary to popular opinion, it is not how loud, but how even the bass is.   For reference only, I have taken it further than most people!

https://www.stereo.net.au/forums/topic/242166-using-multi-subs-mso-to-get-even-bass-in-room-across-sitting-positions/?do=findComment&comment=4739911&_rid=161413

 

It is clear that you have a bass problem in the room.  You can fix this by treating the room, but most people do not do it correctly and thoroughly.  This is because it is a hard problem to solve.  This is an old but still good guide

https://www.hifizine.com/2011/06/bass-integration-guide-part-1/

It will give you an idea oh how to do this properly, and some of the REW measurements to be done.

 

It looks like VAF DC-6 is a proper centre speaker.  I think a few people thought you were using a normal speaker sitting horizontally.

 

Not sure what your other speakers are, but ideally, get a centre speaker which is the same brand and series as your fronts.  Do not scrimp on the centre; it carries most of the dialogue and is as important, maybe more so, as the fronts.

 

Please do not forget to move your speakers away from the corners.  To give you a better picture of how corners affect the sound, please look at the second graph of this post  (my stereo speakers can compensate for corners).

https://www.stereo.net.au/forums/topic/342649-so-in-shared-rooms-why-choose-dsp-enabled-active-speakers/?_rid=161413

 

Once you have the speakers, subs, room treatment sorted out,  I can take you through some ARC advanced settings that can further improve the bass.  In the mean time, suggest not playing with ARC because you are changing lots of things.

 

It may be high quality, but is it acoustically transparent ?  This is essential when you put speakers behind a screen.

Some great info there thanks Snoopy. Looks like I have some reading to do.

 

For clarity, all of my seven main channels are VAF floorstanders. Yes the DC-6 is a ‘proper’ centre speaker ie it was designed for that purpose to sit horizontally. Tweeters for all three LCR speakers are aligned.

 

My screen fabric is acoustically transparent (AT) and perforated to let sound through so likely no issue there. It’s a 4K fabric I sourced from OzTheatre screens.

7 hours ago, Benje said:

Oz Justin

 

lots of good advice from Snoopy8 above.

 

Re the acoustic transparent screen,

I wanted to make sure the screen wasn't affecting the centre speaker issues.

It may be fine.

Next time you are running ARC (noting Snoppy8's point about not changing too much), can you check the performance of the centre speaker with the screen and also with it wheeled away?

If the in-room response is the same, the issue is definitely not the screen.

I doubt that the dc-6 is the problem, unless there is a fault with it eg a damager speaker cone or cross-over.

 

If you do this, you could try moving the centre speaker a but lower, or a bit higher, or vertically rather than horizontally.

Of course, you might not see any variation.

 

Check how you can use ARC to test a single speaker's response.

 

Benje

I’ll give the individual speaker testing a go with ARC this weekend. 
Need to put a game plan together now so I can work through the suggestions methodically and gauge their impact. So much to learn and so little time. 😊

  • Like 2
Link to post
Share on other sites
12 hours ago, OzJustin said:

That looks like a beast! Unfortunately I think it’s a bit beyond my budget.  How would one of those PSA subs compare to two or three separate subs in terms of frequency response and whole room balance? Is it the equivalent of three separate subs despite the single enclosure?

Some great info there thanks Snoopy. Looks like I have some reading to do.

 

For clarity, all of my seven main channels are VAF floorstanders. Yes the DC-6 is a ‘proper’ centre speaker ie it was designed for that purpose to sit horizontally. Tweeters for all three LCR speakers are aligned.

 

My screen fabric is acoustically transparent (AT) and perforated to let sound through so likely no issue there. It’s a 4K fabric I sourced from OzTheatre screens.

I’ll give the individual speaker testing a go with ARC this weekend. 
Need to put a game plan together now so I can work through the suggestions methodically and gauge their impact. So much to learn and so little time. 😊

Do please get the speakers out from the wall a bit first. Your room will be full of modes around 80Hz. You want to be EQed as much as possible to what is coming directly out of your speakers rather than the ringing of your room at these modes. 

Link to post
Share on other sites
15 hours ago, OzJustin said:

That looks like a beast! Unfortunately I think it’s a bit beyond my budget.  How would one of those PSA subs compare to two or three separate subs in terms of frequency response and whole room balance? Is it the equivalent of three separate subs despite the single enclosure?

 

It's a single subwoofer despite having three woofers.

There are pros and cons to one subwoofer versus multiple.
With multiple unless you have them set up well they can cancel each other out.

Link to post
Share on other sites
On 23/06/2021 at 8:16 AM, OzJustin said:

Do I really want the same crossover point for LCR even when the left and right speakers are far more capable in the lower Hz?

not if the centre channel can't manage the bass that your mains can...but your centre channel "should" very closely match your L/R speakers, otherwise a pan from side to side won't sound like it should - you want the tonal balance matched across L/C/R

 

On 23/06/2021 at 7:34 AM, OzJustin said:

I haven't tried vertical orientation. Would that suit a VAF DC-6 design?

not if it's meant to lay flat - best to keep it flat but understand it's response will sound "diifferent" to your mains.

Ideally you want left/right/centre to sound identical - especially the dispersion pattern between tweeter and mids.

The "lay down" orientation of many centre speakers is a compromise - better centre speakers maintain a vertical placement of tweeter and mid....

On 23/06/2021 at 8:16 AM, OzJustin said:

Perhaps I should be hunting for another VAF DC-X floorstander to replace the smaller existing centre.

^ agreed

 

 

On 23/06/2021 at 12:04 PM, Snoopy8 said:

It is clear that you have a bass problem in the room.  You can fix this by treating the room, but most people do not do it correctly and thoroughly.  This is because it is a hard problem to solve.

but not many people have that alcove crying out for a bass trap

 

On 23/06/2021 at 8:16 AM, OzJustin said:

Is there an easy way to test this absorber theory before going through the effort?

Yes - buy some bags of absorption and stack them in the gap, without any frame - you could even leave the batts in their bags...but you'd need more bags to close the gap.

 

My first attempt at room treatment used batts still in their bags, approx 40 bags stacked around the room - the impact on the room sound was profound.

I didn't realise back then that they weren't making any difference to the low bass - the room just let all the low bass out.

The batts cleaned up >150Hz wonderfully.

 

On 23/06/2021 at 8:16 AM, OzJustin said:

but I gather near airtight isn’t needed

correct - absorption doesn't require a seal - but you want the gap mostly covered

 

cheers

Mike

  • Like 1
Link to post
Share on other sites
On 20/06/2021 at 10:35 PM, OzJustin said:

 

 

Some questions I have based on basic reading/tutorials etc I've perused:

 

There's really little impact to the things you listed.

 

As for how much and what type of treatment you might need..... you need other types of measurements of the room than the one you posted.    Bass traps are almost always helpful, but they need to be real big  (almost everything you seen sold as a bass trap should be referred to the ACCC, *wink*)

 

PS - the bass region looks great in your masurement...   To get better seat to seat, or more headroom vs distortion, you can add more subs.

Link to post
Share on other sites
On 21/06/2021 at 11:52 PM, Snoopy8 said:

Having speakers in the corners of the room is a NO, NO,  Your bass becomes "boomy" with peaks in the bass region, as shown by your measurements. 

 

It's fine, in general (although the specifics are a rabbits warren).

 

The only reason it becomes "boomy" is that the frequency response increases (which you can see in the measurements, if you "smooth" it)

 

The "peaks and dips" are pretty much the same,  just moved in frequency .... but they're being corrected ok.

Link to post
Share on other sites
Posted (edited)

So I finally had a few minutes to try the ARC Quick Measure feature. Here's what I came up with.

 

Centre speaker:

Snapshot 1 is default screen location

Snapshot 2 is screen moved forward 30cm

Snapshot 3 is with the screen removed

It's showing 75.dB SPL

Observations - There is virtually no difference to the curve (apart from a very minor anomaly below 40Hz) whether the screen is within 10cm of the speaker or further away. There is a slight boost from 7k - 20k Hz with the screen removed but nothing too significant. I obviously require the screen or I won't be watching movies etc though.

228326741_CentreSpeaker-DefaultLocationvsScreen30cmForwardvsScreenRemoved.jpg.bb1e03894ba14720c7bf538985f894bf.jpg

 

Front left speaker:

Snapshot 1 is default location

Snapshot 2 is 30cm forward off the wall

Snapshot 3 is 40cm forward and 30cm right (so it's much closer to the screen)

It's showing 71dB SPL - Does that suggest I need to bump up my reference level?

1644618031_FrontLeftSpeaker-DefaultvsForwardvsForwardInward.jpg.6d22d9f502daff157aa879e7cb82389b.jpg

 

Subwoofer:

Snapshot 1 is default location mid-left wall

Snapshot 2 is default location but max volume on back of sub

Snapshot 3 is 30cm forward and slightly right from the default location

Snapshot 4 is relocated to the front left wall

Snapshot 5 is relocated to the front left wall but max volume on back of sub

It's showing 78.5dB SPL

Observations - There's a big dip at 35Hz and again at roughly 120Hz regardless of those two locations (though front left seems to improve the 35Hz dip a little).

873495459_Sub-DefaultvsMaxvs30cmRightvsFrontLeftvsFrontLeftMax.jpg.79cc5bc078184a5672fe0b54d8e2c6af.jpg

 

Thoughts on these measurements and what to try next? Am I aiming for as ruler flat as possible based on the best location I can identify, then try to improve further with acoustic treatment, then ARC Genesis room correction as the final step?

 

Edited by OzJustin
Added centre speaker results
  • Like 2
Link to post
Share on other sites
5 minutes ago, OzJustin said:

Thoughts on these measurements and what to try next?

 

For your SW.  Position 5 is a significant improvement.

 

For the speaker, I would try moving it even further out, to see if you can find any position that fills in dips.

 

As for for the level, I don't know.   Your original measurement were ~60dB .... which is also quiet.   It might not be accurate.   Do the test signals sound quite loud?    I wouldn't worry.

 

 

5 minutes ago, OzJustin said:

 then try to improve further with acoustic treatment

 

For account treatment, I wouldn't be looking at these types of frequency response charts to spec it (or tune it when you get something).

 

If the room is pleasant / comfortable to have a conversation in.... then you might even need nothing. 

 

If it works with your screen I would not be afraid to sit closer... toe the speakers in more.... and maybe some absorption on the back wall.

  • Like 2
Link to post
Share on other sites
6 hours ago, davewantsmoore said:

 

For your SW.  Position 5 is a significant improvement.

 

 

Agreed, position 5 is definitely an improvement. ARC should be able to smooth that out

Link to post
Share on other sites
On 25/06/2021 at 3:10 AM, almikel said:

Yes - buy some bags of absorption and stack them in the gap, without any frame - you could even leave the batts in their bags...but you'd need more bags to close the gap.

 

My first attempt at room treatment used batts still in their bags, approx 40 bags stacked around the room - the impact on the room sound was profound.

I didn't realise back then that they weren't making any difference to the low bass - the room just let all the low bass out.

The batts cleaned up >150Hz wonderfully.

In my post above I say my absorption isn't effective for absorbing low bass - your situation is different with that alcove.

The absorption in my room has minimal air gaps to boundaries, so the absorption doesn't do much under 150Hz.

 

Apologies if I sound like a broken record, but closing that alcove off (sealing it is not required) with a moveable trap constructed of fluffy batts - batt width deep and stacked (say 430mm deep) - your "absorption+alcove" becomes a proper bass trap for your room.

 

It's rare that absorption is effective <150Hz or so without getting ridiculously large/deep.

 

Absorption traps are "velocity" devices - they work by slowing down air particles, and are best placed at high velocity zones.

At a boundary the air particle velocity is zero, and the highest velocity = wavelength/4 away from the boundary.

Hence why absorption treatment is usually air gapped away from boundaries to work better - esp for lower frequencies.

 

At 150Hz: V=f x wavelength, with V being the speed of sound 343m/s

Wavelength = 343/150 = 2.29m

Max velocity of air particles @150Hz is Wavelength/4 = 0.57m off the room boundary.

 

Most rooms don't have the flexibility/space of having absorption placed 570mm from a room boundary to absorb the maximum velocity for 150Hz.

 

The good news is that absorption starts working as long as the air particle velocity is > 0, but for absorption to be effective at lower frequencies the treatment needs to be very large/deep/air-gapped.

 

Covering that gap to your alcove with absorption gives you a free "air gap" to allow absorption to work lower.

 

Mike

Link to post
Share on other sites
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Jventer
      Very interesting article and review here:
      http://www.theabsolutesound.com/articles/acoustic-geometry-pro-room-pack-10-acoustic-treatment-package/
    • By Unsound
      Item: Vicoustic Super Extreme Bass Traps - Wenge x 2
      Location: Camberwell. Vic
      Price: $590 ONO. Plus PayPal and freight (if required) - prefer local buyers. Cost $800.
      Item Condition: As new, just several months old.
      Reason for selling: I was “advised” that the colour was not conducive to a long term relationship, so I changed to white (x 4 - heh, heh)
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info: I have original packaging, but they would not be attractive to ship.
       
      I have left removable adhesive strips on the sides - these can easily be removed with no damage.
       
      These little beauties made a fantastic difference to my room (I had a 125Hz peak, beautifully handled). I’ve now invested in 4 more - WHITE!
       
      Pictures:


    • By steven365
      Item: QRD Acoustic diffusers made from real wood. 60cmx120cmx10cm
      Location: Sydney
      Price: $350 $250 each. Priced dropped for quick sale. Only a few left.
      Item Condition: New
      Reason for selling: Was going go build my dedicated listening room but now I have other priorities in my life : )
      Payment Method: Pickup - Cash, Paypal, COD Only.
      Extra Info: These are quite large, so I would prefer local pick up. Or if you are living in another state you need to organize courier yourself.
      Some more info from internet:
       
      "A vertically positioned QRD diffuser diffuses sound in a horizontal pattern. A horizontally positioned diffuser spreads sound energy out in a vertical array of energy. They are essential components of your room if you want to truly connect with your music. Proper room diffusion is not an option, it is a necessity! Poor diffusion is a room distortion that is present in all rooms both small and large. In fact, it is one of four main acoustical distortions found in your room right now. Diffusion technology is a must in all listening, home theater, and professional recording studios. Quadratic diffusion is the most time tested and proven method of diffusion used by professional recording studio builders for years the world over."
       
      Pictures:

       
       
       
    • By zydeco
      FS: ST120-80 Bass Traps x 4
      Location: Perth
      Item Condition: Very good (8/10) – minor blemishes on front panel
      Reason for Selling: No longer being used
      Price: $375 the Lot
      Payment Method: Cash, Bank Check, Electronic Funds Transfer
      Extra Info: See http://soundacoustics.com.au/product/bass-traps/bt120-80-corner-bass-trap/ Local pick-up only.
       
       
    • By bozzie1704
      Item: Acoustic diffuser
      Location: Brunswick VIC 3057
      Price: $100 each
      Item Condition: Used
      Reason for selling: No longer needed
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info: 6 available 600 X 600 X 109mm 
      Pictures:



×
×
  • Create New...