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Old 08-03-2012, 10:48 AM
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I'm not sure about the foam underlay, but if it works it sounds like a good option as I would use it too smile.gif

What I would suggest is taht whatever you end up using, if it isn't black, you can cover it (the foam on the screenwall) with something like a black speaker grill cloth. It's AT like the screen and will help hide anything that's not black behind the screen. Some black velvets are said to be AT as well, and they may be a better choice as they will probably be blacker.

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Old 08-03-2012, 02:04 PM
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The product is not foam underlay it is black rubber underlay.

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Old 08-03-2012, 06:58 PM - Thread Starter
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Murray, thanks for your comments. Very impressive set up you have there. I don't feel I am qualified to definitively answer your question if the dense black rubber would work since I did not design my baffle wall.

For what it's worth, I looked back at my documentation of my build and my foam consists of Auralex wedges and Auralex Platfoam. The Auralex wedges are arguably more cosmetic than function. The wedges are 2 inches. Beneath the wedges are the Platfoam which is a high density acoustical foam as shown here and I believe mine are 1" thickness. All foam were glued on. 1 inch is 25.4 mm which obviously exceeds 10mm.

So with the above said, I can think of two alternatives to further explore,
1) Consult with qualified individual on the effectiveness of the 6 to 10 mm dense black rubber for your application (Hopefully someone on this forum can better answer and chime in) .
2) Consider re-do of screen wall to allow for proper acoustic foam.

There may be other, better solutions but unfortunately I can only answer questions from my build because that is all i know.
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Old 08-04-2012, 09:09 AM
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Well the purpose of the 'black stuff' on the baffle wall is generally twofold.
- absorb light that gets behind or to the side of the screen. If you have a black backing on your screen then you don't need the area behind to be black
- absorb the reflected sound back off the screen (yes, even though the screen is AT there is some reflections)

The rubber underlay is for something different. It doesn't have any sound absorbing properties to speak of really. It's also very heavy.

If you don't have black backing on your screen then I'd just paint the area behind a flat black. The other option is to pull some thickness off a 1" fiberglass to get it to fit, though that would be messy. Another option is just rehanging your screen to give you more room.

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Old 08-04-2012, 02:07 PM
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Hi Nyal

My AT screen has a white back but I have no reflections as I painted the whole back wall and the speaker cases matte black. My sound is amazing but I was told it can even be better if I tread the back wall with a sound absorbent material. One has mentioned black felt, any thoughts or is it a waste of time?

I can also get the dark grey sponge that you often see in packing cut to any thickness I want from Dunlop http://www.dunlopfoam.co.nz/Foam/Foam-Products/Filter%20Foam/

I can not move the screen in anyother position.

Thanks for any help on this.

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Old 08-04-2012, 05:36 PM
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Most people on this forum that are based in the US use a 1" thick Linacoustic which is designed as an acoustic duct liner I believe (it just happens to do the job in this application). There is probably something similar where you are but finding it might be tricky.

You need to find a product that will help absorb the sound that reflects back off of the screen so you don't have any sound bouncing between screen and baffle wall. I would think rubber would be reflective and better suited to sound proofing rather than acoustic application, but the correct type of foam should be better. I wonder if you did a google search in NZ for acoustic duct liner what would turn up.

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Old 08-04-2012, 06:12 PM
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Originally Posted by Gary Lightfoot View Post

Most people on this forum that are based in the US use a 1" thick Linacoustic which is designed as an acoustic duct liner I believe (it just happens to do the job in this application). There is probably something similar where you are but finding it might be tricky.
You need to find a product that will help absorb the sound that reflects back off of the screen so you don't have any sound bouncing between screen and baffle wall. I would think rubber would be reflective and better suited to sound proofing rather than acoustic application, but the correct type of foam should be better. I wonder if you did a google search in NZ for acoustic duct liner what would turn up.
Gary

What do you think of this, I can get this in black 12mm. http://www.forman.co.nz/upload/pdf_documents/acoustop%20absorber161A.pdf

I would have to keep the smooth surface against the wall.

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Old 08-04-2012, 06:29 PM
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It looks OK to my untrained eye, but it might be worth asking someone like Ted White or Dennis Erskine what they think. Considering you've got a limited space to work with and can't use an inch of foam, it looks like it might be your best choice.

I once used foam backed carpet on the lower side walls to tame the slap echo in my last HT and it worked well. The trouble is I've no idea what it was doing overall as I didn't measure the room in any way, so although it removed the echo, I reckon there was lots of room for improvement using the correct products. It could be a cheap alternative but a pain to remove if it doesn't work.

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Old 08-06-2012, 09:13 PM
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Quote:
Originally Posted by Gary Lightfoot View Post

Most people on this forum that are based in the US use a 1" thick Linacoustic which is designed as an acoustic duct liner I believe (it just happens to do the job in this application). There is probably something similar where you are but finding it might be tricky.
You need to find a product that will help absorb the sound that reflects back off of the screen so you don't have any sound bouncing between screen and baffle wall. I would think rubber would be reflective and better suited to sound proofing rather than acoustic application, but the correct type of foam should be better. I wonder if you did a google search in NZ for acoustic duct liner what would turn up.
Gary

Yep felt or jute would work. I use Auralex Platfoam on my baffle walls, normally two layers which makes 2" thickness.

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Old 08-06-2012, 09:42 PM
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Quote:
Originally Posted by Nyal Mellor View Post

Yep felt or jute would work. I use Auralex Platfoam on my baffle walls, normally two layers which makes 2" thickness.

Jute, thats interesting, would never had thought. Would be difficult to find in flack though wont it?

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Old 03-05-2014, 12:09 PM
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Nice looking room - and similar dimensions to a space I may have to work with. This link is going to the wife for her thoughts.

One question -- with the AT screen - is there EVER a time you can see the speakers or a shadow of the speakers or any lack of white uniformity across your front AT screen? Since you can see through from behind the screen with the blue lights on the speakers I'm curious if you can ever make out the shapes from the front - without the backlight on.

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Old 03-05-2014, 09:24 PM - Thread Starter
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Originally Posted by Archaea View Post

Nice looking room - and similar dimensions to a space I may have to work with. This link is going to the wife for her thoughts.

One question -- with the AT screen - is there EVER a time you can see the speakers or a shadow of the speakers or any lack of white uniformity across your front AT screen? Since you can see through from behind the screen with the blue lights on the speakers I'm curious if you can ever make out the shapes from the front - without the backlight on.

Thanks Archaea. the only time I can see the speakers is when I have the blue LEDs on. With LEDs off (ie during a movie), I only see the beautiful image the projector + Seymour screen produces biggrin.gif
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Old 09-22-2015, 08:04 AM
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Our humble theater is almost done. I'll update this with more "finished" pictures later.The gear
  • BenQ W7000
  • ISCO 4XL with Cineslide
  • Seymour Centerstage XD 125" wide 2.37
  • Oppo BDP-93
  • Toshiba HD-XA2
  • Odyssey Stratos Stereo Extreme
  • Sunfire Cinema Grand
  • Onkyo PR-SC885
  • JTR Triple 12HTs for LCR, four JTR S8s for surrounds, two JTR Captivator S subs
  • SurgeX XR315 and XF2 surge protectors for components and projector
  • URC MX-980 remote with MRFA-3LD-URC lighting control
  • Primacoustic Broadway Broadband, Control Columns and FlexiFusers.
  • Monoprice XLR cables & Belden UTP speaker cables
Updated gear as of 8/7/15
* Sony HW50ES
* miniDSP DDRC-88A
* Marantz 8802A

Nice set-up and doing some room acoustic.
Not enough people take care of the room for sound problems.


Kudo and well done, elegant and functional.


Ray
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Old 09-22-2015, 09:58 AM
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Quote:
Originally Posted by quack724 View Post
Quote:Originally Posted by Archaea 

Nice looking room - and similar dimensions to a space I may have to work with. This link is going to the wife for her thoughts.

One question -- with the AT screen - is there EVER a time you can see the speakers or a shadow of the speakers or any lack of white uniformity across your front AT screen? Since you can see through from behind the screen with the blue lights on the speakers I'm curious if you can ever make out the shapes from the front - without the backlight on.


Thanks Archaea. the only time I can see the speakers is when I have the blue LEDs on. With LEDs off (ie during a movie), I only see the beautiful image the projector + Seymour screen produces
I notice you have an odyssey amp for ur fronts. How do u like it? I was originally looking at them for my triads but people kept telling me the output wasn't enough cause it wasn't 1.5 x the rms output. Others said to not bother with that because there are so few times you would need that steady of an output to not clip. They are one of those amps that have an internet following but you don't read much about them. It was 2012 when I looked at them last i would say. Right now my head is at ati and ada. Ada cause they make multi channel solutions so i don't have a whole rack of amps.

Thanks a lot. Ur build came out really nice.

Jim
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Old 09-22-2015, 04:47 PM - Thread Starter
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I notice you have an odyssey amp for ur fronts. How do u like it? I was originally looking at them for my triads but people kept telling me the output wasn't enough cause it wasn't 1.5 x the rms output. Others said to not bother with that because there are so few times you would need that steady of an output to not clip. They are one of those amps that have an internet following but you don't read much about them. It was 2012 when I looked at them last i would say. Right now my head is at ati and ada. Ada cause they make multi channel solutions so i don't have a whole rack of amps.

Thanks a lot. Ur build came out really nice.

Jim
Thanks for the compliment Jim. Re: Odyssey, I actually removed it temporarily from my set up due to hum when I switched out my old Onkyo SSP to the Marantz. I have not taken the time yet to root cause the issue. So I am on 5.1 at the moment. When the Odyssey was in (and no hum), I thought the sound was very good. I don't have "audiophile" ears .. meaning, I couldn't tell you that there was a striking difference between my Sunfire vs the Odyssey. In my set up, the JTRs are very efficient so I doubt that I even made either of my amps break a sweat. I think most people use Odyssey for 2 ch and not so many for HT.. maybe that is why you don't read much on them in HT forums. One plus on the ADA and ATI is the built in remote trigger if you care about that. Having multichannel amp can definitely save rack space as you said.. especially if you have the newer OO / 3D surround formats in your set up now or plan to in the future.

Edit: I know some/many will argue against multichannel for LCR ( the merits of not sharing a power supply ). I guess it comes down to budget & priorities.

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Old 09-22-2015, 07:21 PM
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Thanks for the compliment Jim. Re: Odyssey, I actually removed it temporarily from my set up due to hum when I switched out my old Onkyo SSP to the Marantz. I have not taken the time yet to root cause the issue. So I am on 5.1 at the moment. When the Odyssey was in (and no hum), I thought the sound was very good. I don't have "audiophile" ears .. meaning, I couldn't tell you that there was a striking difference between my Sunfire vs the Odyssey. In my set up, the JTRs are very efficient so I doubt that I even made either of my amps break a sweat. I think most people use Odyssey for 2 ch and not so many for HT.. maybe that is why you don't read much on them in HT forums. One plus on the ADA and ATI is the built in remote trigger if you care about that. Having multichannel amp can definitely save rack space as you said.. especially if you have the newer OO / 3D surround formats in your set up now or plan to in the future.

Edit: I know many will argue against multichannel ( the merits of not sharing a power supply ). I guess it comes down to budget & priorities.

You have a nice list of impressive equipment.


For your Hum problem.
The way I read this, it started when you switch the Onkyo to the Marantz!?


Did you change anything else?
If not, I can remove too much equipment on one electrical circuit.
Speakers wires crossing patch cord,
XLR patch cord remove hiss but not sure about Hum.


The only thing, I can think about is, if your AV8802 is built the same way as my AV8801.
It is a power cord without ground.
I had some issue with electrical static until, I use the ground knob in the back.
On my AV8801, their is a little knob on the back left end side, where you can put a ground wire to ground it to earth.
In my room, it was easy since the equipment is right next to the house ground.


Maybe it is that simple to ground the unit since most equipment that need ground use a 3 prongs power plug. Other than that, I don't know what to suggest if nothing else change.


Ray
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Old 09-23-2015, 06:15 AM
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thats one well build projector mount!
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Old 09-23-2015, 10:32 AM - Thread Starter
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Originally Posted by darthray View Post
You have a nice list of impressive equipment.


For your Hum problem.
The way I read this, it started when you switch the Onkyo to the Marantz!?


Did you change anything else?
If not, I can remove too much equipment on one electrical circuit.
Speakers wires crossing patch cord,
XLR patch cord remove hiss but not sure about Hum.


The only thing, I can think about is, if your AV8802 is built the same way as my AV8801.
It is a power cord without ground.
I had some issue with electrical static until, I use the ground knob in the back.
On my AV8801, their is a little knob on the back left end side, where you can put a ground wire to ground it to earth.
In my room, it was easy since the equipment is right next to the house ground.


Maybe it is that simple to ground the unit since most equipment that need ground use a 3 prongs power plug. Other than that, I don't know what to suggest if nothing else change.


Ray
Thanks very much for the suggestions Ray. I actually had hum with the Onkyo too. I wrote a post on this issue in 2012 but did not get replies. You are the first to comment

Things I've tried since my 2012 post
1) Jensen isolation transformer but it did not help.
2) Isolating the power cords to one side of the rack but the Odyssey amp has it's power cord sticking out back from the middle so it's hard to prevent the Odyssey from not being near the non power cables. My Odyssey is 2nd to bottom shelf. I might try to place it on bottom shelf to see if having it's power cord even further away helps.
3) For whatever reason, there was a time when I used RCAs for the Odyssey L&R channels (instead of XLR like I do with my Sunfire 5 ch), the hum would go away and be stable but when I re-insert XLR to L&R *or* put back the same RCA cables I would get the hum again. So I can't consistently reproduce the issue or workaround.
4) Remove all other components except Marantz, Surge X, Odyssey . Odyssey to L&R speakers alone (no Marantz) = no hum.

I will look into your ground suggestion.

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Old 09-23-2015, 07:51 PM
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Thanks very much for the suggestions Ray. I actually had hum with the Onkyo too. I wrote a post on this issue in 2012 but did not get replies. You are the first to comment

Things I've tried since my 2012 post
1) Jensen isolation transformer but it did not help.
2) Isolating the power cords to one side of the rack but the Odyssey amp has it's power cord sticking out back from the middle so it's hard to prevent the Odyssey from not being near the non power cables. My Odyssey is 2nd to bottom shelf. I might try to place it on bottom shelf to see if having it's power cord even further away helps.
3) For whatever reason, there was a time when I used RCAs for the Odyssey L&R channels (instead of XLR like I do with my Sunfire 5 ch), the hum would go away and be stable but when I re-insert XLR to L&R *or* put back the same RCA cables I would get the hum again. So I can't consistently reproduce the issue or workaround.
4) Remove all other components except Marantz, Surge X, Odyssey . Odyssey to L&R speakers alone (no Marantz) = no hum.

I will look into your ground suggestion.

I will try to help with some of my basic knowledge.
I would make a new thread into the speaker or AVR/pre-pro, this would get you a lot more traffic and some with more knowledge will reply.


Pm me so I know where to look!


It sound like your Hum is only from your main and not your surrounds or center.
Also you use "Jensen isolation transformer ".


So I will go with the obvious.
pre-amp, amp and speaker cable.


I do not think it is the pre-amp (or the patch cord for signal since you tried, RCA and XLR) since you had switch between two of them, but let's make sure.
Did you try to change the patch cord from the main and switching them for the surround?
If the Hum move to the surround instead of the main, the pre-amp could be the culprit.


If not, put back all patch cord where they belong.
Switch your speaker wires from your main to your surround.
If the Hum move to the surround, then the amp is at fault or the wires going to-it.


For the speakers, my only suggestion is to make sure they cross any power cord and patch cord like a + sign, but not in parallel, should not matter that much with patch cord, but we never know.


The last thing I can think about.
In my system I have two dictated 20 amp circuit one for my 2 subs and one for the amp, also one 15 amp for projector, pre-amp and blue-ray.
The one thing I made sure, all those circuit were on the same side of the main house circuit board (you have a left and right side and sometime with audio, it can introduce a Hum problem).
I also doubt it would be the problem since you got a Hum in your main only.


Lots of thing to try, and honestly Hum problem in a system can be the most difficult one to find the source.
Even when found, the cure can be difficult and this is why I made a suggesting of a new tread with more traffic.


Ray

Last edited by darthray; 09-24-2015 at 07:25 PM.
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Old 09-23-2015, 07:55 PM
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thats one well build projector mount!

+1 on that


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Old 09-25-2015, 09:30 PM - Thread Starter
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I will try to help with some of my basic knowledge.
I would make a new thread into the speaker or AVR/pre-pro, this would get you a lot more traffic and some with more knowledge will reply.


Pm me so I know where to look!


It sound like your Hum is only from your main and not your surrounds or center.
Also you use "Jensen isolation transformer ".


So I will go with the obvious.
pre-amp, amp and speaker cable.


I do not think it is the pre-amp (or the patch cord for signal since you tried, RCA and XLR) since you had switch between two of them, but let's make sure.
Did you try to change the patch cord from the main and switching them for the surround?
If the Hum move to the surround instead of the main, the pre-amp could be the culprit.


If not, put back all patch cord where they belong.
Switch your speaker wires from your main to your surround.
If the Hum move to the surround, then the amp is at fault or the wires going to-it.


For the speakers, my only suggestion is to make sure they cross any power cord and patch cord like a + sign, but not in parallel, should not matter that much with patch cord, but we never know.


The last thing I can think about.
In my system I have two dictated 20 amp circuit one for my 2 subs and one for the amp, also one 15 amp for projector, pre-amp and blue-ray.
The one thing I made sure, all those circuit were on the same side of the main house circuit board (you have a left and right side and sometime with audio, it can introduce a Hum problem).
I also doubt it would be the problem since you got a Hum in your main only.


Lots of thing to try, and honestly Hum problem in a system can be the most difficult one to find the source.
Even when found, the cure can be difficult and this is why I made a suggesting of a new tread with more traffic.


Ray
Ray, thanks for taking the time for the write up above. I genuinely appreciate the suggestions! Honestly, I simply have not been motivated to figure out the what is causing the hum right now. As you said above, it can be/has been time intensive to figure it out the root cause. Two young kids and work aside, when I can carve out some time my more immediate priority is to dial in my miniDSP 88a with the recent Marantz 8802A. I may resurrect with the old thread with updates when I carefully document the steps I have tried.

I will say that I can't swap LCR with surround speaker cables since my surround speaker cables are inside my walls. But I would not suspect speaker cables as my LCRs have no hum with my Sunfire 5 ch amp. Also I had hum with both the old Onkyo and Marantz 8802A SSPs.
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Old 09-26-2015, 01:11 PM
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Originally Posted by quack724 View Post
Ray, thanks for taking the time for the write up above. I genuinely appreciate the suggestions! Honestly, I simply have not been motivated to figure out the what is causing the hum right now. As you said above, it can be/has been time intensive to figure it out the root cause. Two young kids and work aside, when I can carve out some time my more immediate priority is to dial in my miniDSP 88a with the recent Marantz 8802A. I may resurrect with the old thread with updates when I carefully document the steps I have tried.

I will say that I can't swap LCR with surround speaker cables since my surround speaker cables are inside my walls. But I would not suspect speaker cables as my LCRs have no hum with my Sunfire 5 ch amp. Also I had hum with both the old Onkyo and Marantz 8802A SSPs.

No worry


I know too well what it is to not have enough time.
Good luck for the future.


Ray
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Old 09-26-2015, 06:23 PM
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Quote:
Originally Posted by quack724 View Post
Ray, thanks for taking the time for the write up above. I genuinely appreciate the suggestions! Honestly, I simply have not been motivated to figure out the what is causing the hum right now. As you said above, it can be/has been time intensive to figure it out the root cause. Two young kids and work aside, when I can carve out some time my more immediate priority is to dial in my miniDSP 88a with the recent Marantz 8802A. I may resurrect with the old thread with updates when I carefully document the steps I have tried.

I will say that I can't swap LCR with surround speaker cables since my surround speaker cables are inside my walls. But I would not suspect speaker cables as my LCRs have no hum with my Sunfire 5 ch amp. Also I had hum with both the old Onkyo and Marantz 8802A SSPs.
Hope this helps with the Humm your getting I made a thread about how I fixed the speaker and sub hum I had in my room. Click the link below.Speaker Humm fix
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