First Reflection Point Question

F

Fastfwd

Audioholic Intern
I've been watching the new Youtube series on acoustic treatments. My question is pertaining to the 'first reflection point' if you have your mains toed in past your main listening position. This was actually a topic discussed here:
The goal in this is to make the sweet spot wider and in theory I believe it makes each position on a couch a 'sweet spot.'

So, if I'm looking to treat the first reflection point am I not now trying to place treatment for the speaker on the opposite side of the room? The closer speaker to the wall can't really be projecting sound at that wall.

From what I gather so far if you ask a dozen acoustic treatment people the same question you will get a dozen different answers. So, maybe this is a pointless question.

If it helps understand at all - I have a room that is about 12 x 17 with 8 foot ceilings. One side (call it the right side) opens up into another room with a large 6 foot opening and the other (left) a simple doorway size opening. My right main is in front of a big window with a curtain behind it. The left main only has about a half a foot less space to the wall on that side of the room with a solid wood door taking up some of that space behind it. Both have about 5 feet give or take from the side walls.

I pretty consistently find that I have to pull down the right channel about 2-3 db and maybe boost the left 1-2 to keep the sound stage centered. No more than 3db total generally. It's just so weird that it's not always super consistent. I might zero it out and with some albums it may sound fine, but with other albums it is clearly off-center without adjustment.

I thought maybe my uneven length and different speaker cables played a role. I replaced those with some even lenght Bluejeans speaker cables and it sounded better, but didn't fix it. I also had a bigger and more solid media rack on the right side and I recently replaced that with an open style very short rack and that really didn't fix it either. So, I'm thinking that the large opening into the other room probably plays a big role in it, but that the absorption from the curtains might add to the uneven soundstage that favors that side.

I ordered a couple of absorption panels. I got a 24"x48"x 2" deep for directly behind the left speaker. I got 2" because I'm afraid to take away a full 4" from behind it to the wall. The right speaker has about 16" to the curtains (not the window) and the left has just less than 20" (to the solid wall behind it). I guess I could have gone 4" behind it.

I did order a 24" x 48" x 4" that I have intended to use for that first reflection on the side wall where I have plenty of room for a 4" panel. Is that a total waste of a 4" panel or will it work to absorb some ambient sound waves in the lower frequencies from the room in a beneficial way? I'm guessing not nearly as much as it would directly behind a rear ported tower speaker.

I ordered the 2" in black to blend in behind the speaker and the 4" in white to contrast with the color of the walls. So, unless I change the order it's not going to be easy to swap them around. Maybe I should just change it to make them both 4", but that's going to start really eating up the distance to the wall for that side. I'm questioning the pros vs cons of that.

I do not have a calibrated mic for REW if anyone wants to know that. I've only used Audyssey for room correction. It does reflect a few dips/spikes around the 100hz region that it claims to be smoothing out, but I suppose without running REW I don't really know how well it actually is doing that. I also haven't yet attempted using bass traps. I'm frankly a little stunned at the prices being asked for some of this stuff. For what appears to just be some foam. Some of the Amazon offerings aren't getting the best reviews for quality of what you get for the cheaper stuff.

I would sure like to fix the uneven soundstage issues. It can be irritating to have to make those adjustments so frequently.
 
ryanosaur

ryanosaur

Audioholic Spartan
Dude. You are shooting in the dark, like most people that do this. Without understanding some basic principles of Acoustics and taking measurements, shooting in the dark is ALL you will be doing.
Worrying about cable lengths? You need miles of cable to make an audible difference. Worrying about the diffraction caused by a piece of furniture? This is only really useful in the most academic of considerations.

Forgive that I am coming across as harsh: it is not intended as such.

If you want to get a remedial grip on this:
Get a Umik 1 and learn how to use REW. This will cost you ~$100 and some time.
Read a book like:

In the mean time, post some photos of your room so we can see what you are dealing with. Proper setup is key, and there are usually a lot of FREE things you can do that will greatly improve your situation.
Also, what are your speakers? Wide dispersion Speakers will require different considerations than controlled directivity Speakers. For example, I know with the latter you can do time-intensity trading as you described in your very first paragraph. Wide dispersion, not so much.

Lastly, for now, I have seen so many stories of people that went crazy treating their rooms to the nines only to throw a bunch of that cr@p away once they learned more, and actually improved the sound.
 
nathan_h

nathan_h

Audioholic
Yeah post some photos and share you speaker models. You may still not get consistent advice but it will give you better odd of getting usable ideas.

And you can do this without using a measurement microphone.

Ultimately measurements are useful but sometimes there are a few things to try that may help just using the gear you have already.
 
F

Fastfwd

Audioholic Intern
Dude. You are shooting in the dark, like most people that do this. Without understanding some basic principles of Acoustics and taking measurements, shooting in the dark is ALL you will be doing.
Worrying about cable lengths? You need miles of cable to make an audible difference. Worrying about the diffraction caused by a piece of furniture? This is only really useful in the most academic of considerations.

Forgive that I am coming across as harsh: it is not intended as such.

If you want to get a remedial grip on this:
Get a Umik 1 and learn how to use REW. This will cost you ~$100 and some time.
Read a book like:

In the mean time, post some photos of your room so we can see what you are dealing with. Proper setup is key, and there are usually a lot of FREE things you can do that will greatly improve your situation.
Also, what are your speakers? Wide dispersion Speakers will require different considerations than controlled directivity Speakers. For example, I know with the latter you can do time-intensity trading as you described in your very first paragraph. Wide dispersion, not so much.

Lastly, for now, I have seen so many stories of people that went crazy treating their rooms to the nines only to throw a bunch of that cr@p away once they learned more, and actually improved the sound.
Well, thanks for taking the time to respond. I'm afraid I'm not particularly eager to post photos of my electronics in my home unfortunately. I'm just a little too paranoid about photos of my gear falling into the wrong hands. I'm not living in a gated community here.

The speaker cable was more than just unbalanced length. I had one side cabled with some Monoprice cables and I custom cut my own for the other side with the wire that I used to wire up the ceiling speakers. The upgrade to Bluejeans was worth it - trust me. I just hoped it might be the cure for more than it was.

The speakers are Revel F35s if that helps. My understanding is that they have a magnificently even and wide horizontal dispersion. The vertical dispersion may not be quite as terrific for whatever that is worth. I've seen how they measure over at Audio Science Review. I'm sure some ceiling treatment may be helpful, but I'm not going that far just yet.

I just ordered 2 panels to see if I could notice any improvements. Based on the video series happening on the Audioholics Youtube channel it seems to imply that it takes a rather small percentage of overall wall-space coverage to make an improvement. Like 30% mixed dispersion and absorption? That' the guy selling the stuff saying that though.

You are correct that I am shooting in the dark and it's a rather pricey gamble. I considered getting the mic already, but whatever the results of the frequency response at my listening position might be I can't do much more about that from the perspective of setup. I really haven't gone deep into what REL reveals to be honest. I'm guessing it just gets frequency response measurements from your listening position basically.

I've already got my speakers setup how they are going to have to be. There isn't any room to move them away from the wall any further. They really can't be pushed further apart than they are. They are part of a 5.1.4 Atmos home theater and they are situated exactly where they will have to be. I have to work around that now. I can toe them in/out or leave them crossed over in the extreme toe in like they are and that's about it. I've tried it just about every way possible and I like the extreme toe in the best. It does seem to give me a more relaxed listening experience imo.

I've currently got a pretty decent soundstage frankly. Other than the very bizarre off-center thing that happens seemingly randomly. I am getting a shockingly deep soundstage considering there's a 65" OLED screen in-between the mains. It extends pretty wide when called upon from the recording to both left and right. It's not quite as holographic as when I was running standmounts, but it's pretty good.

I do have a rug between my seating position and the mains, but it's not padded. There is also a glass coffee table that I would consider trading for something else, but I need something. The right side of the room has a door that basically kills the possibility of placing absorption at the first reflection point. I almost wonder if the style of the door with panels doesn't perform a little bit of dispersion itself. There is room for an absorption/dispersion panel, but it's not going to be at a reflection point. It would have to be well in front of that.

I also almost consider these to be decorative to an extent too. My walls are bare currently. A set of those dispersion panels on my rear wall over the couch would probably dress the place up a bit. Even if they didn't transform my living room into a better listening room. The prices on those do make me pause until I'm much more sure of what it is that I would be getting and what might be expected. I'm not forking out $250 plus on decorative dispersion panels - they need to function.

These aren't cheap. Just the two panels are hitting me for $191 with shipping. I do hope that I realize some improvement for that kind of money. If I don't then I probably won't be buying any more acoustic treatment.
 
F

Fastfwd

Audioholic Intern
Cancelled the order. I might buy a mic. I'll look into what REW actually does.
 
highfigh

highfigh

Audioholic Overlord
Well, thanks for taking the time to respond. I'm afraid I'm not particularly eager to post photos of my electronics in my home unfortunately. I'm just a little too paranoid about photos of my gear falling into the wrong hands. I'm not living in a gated community here.

The speaker cable was more than just unbalanced length. I had one side cabled with some Monoprice cables and I custom cut my own for the other side with the wire that I used to wire up the ceiling speakers. The upgrade to Bluejeans was worth it - trust me. I just hoped it might be the cure for more than it was.

The speakers are Revel F35s if that helps. My understanding is that they have a magnificently even and wide horizontal dispersion. The vertical dispersion may not be quite as terrific for whatever that is worth. I've seen how they measure over at Audio Science Review. I'm sure some ceiling treatment may be helpful, but I'm not going that far just yet.

I just ordered 2 panels to see if I could notice any improvements. Based on the video series happening on the Audioholics Youtube channel it seems to imply that it takes a rather small percentage of overall wall-space coverage to make an improvement. Like 30% mixed dispersion and absorption? That' the guy selling the stuff saying that though.

You are correct that I am shooting in the dark and it's a rather pricey gamble. I considered getting the mic already, but whatever the results of the frequency response at my listening position might be I can't do much more about that from the perspective of setup. I really haven't gone deep into what REL reveals to be honest. I'm guessing it just gets frequency response measurements from your listening position basically.

I've already got my speakers setup how they are going to have to be. There isn't any room to move them away from the wall any further. They really can't be pushed further apart than they are. They are part of a 5.1.4 Atmos home theater and they are situated exactly where they will have to be. I have to work around that now. I can toe them in/out or leave them crossed over in the extreme toe in like they are and that's about it. I've tried it just about every way possible and I like the extreme toe in the best. It does seem to give me a more relaxed listening experience imo.

I've currently got a pretty decent soundstage frankly. Other than the very bizarre off-center thing that happens seemingly randomly. I am getting a shockingly deep soundstage considering there's a 65" OLED screen in-between the mains. It extends pretty wide when called upon from the recording to both left and right. It's not quite as holographic as when I was running standmounts, but it's pretty good.

I do have a rug between my seating position and the mains, but it's not padded. There is also a glass coffee table that I would consider trading for something else, but I need something. The right side of the room has a door that basically kills the possibility of placing absorption at the first reflection point. I almost wonder if the style of the door with panels doesn't perform a little bit of dispersion itself. There is room for an absorption/dispersion panel, but it's not going to be at a reflection point. It would have to be well in front of that.

I also almost consider these to be decorative to an extent too. My walls are bare currently. A set of those dispersion panels on my rear wall over the couch would probably dress the place up a bit. Even if they didn't transform my living room into a better listening room. The prices on those do make me pause until I'm much more sure of what it is that I would be getting and what might be expected. I'm not forking out $250 plus on decorative dispersion panels - they need to function.

These aren't cheap. Just the two panels are hitting me for $191 with shipping. I do hope that I realize some improvement for that kind of money. If I don't then I probably won't be buying any more acoustic treatment.
Have someone hold a small mirror on the wall and when you can see your speakers from your main listening position, put a piece of painter's tape on the wall. That marks a first reflection spot. Do this for all of the speakers, starting with the front. If the sound goes into an adjacent room, you won't need to absorb it and you can't do it effectively anyway. When you have finished marking the spots, put something between the speakers and walls so you can listen to the difference. Use chairs, a cabinet with a blanket on its face, a piece of scrap plywood or some lumber- make sure to double-layer the blanket(s).

You don't need acoustical panels, you just need something to block the reflections. If you rearrange the furniture and it helps, you have reached the goal.
 
F

Fastfwd

Audioholic Intern
Worrying about the diffraction caused by a piece of furniture? This is only really useful in the most academic of considerations.
I did want to clarify - I got a new amp that didn't fit in the old media rack. I actually needed a more modern open air rack. Once again, it was something that I hoped might benefit the situation, but it only served the primary purpose of getting the new external amp closer to my receiver.

Anyway, I do have a bookcase/rack/stand type piece of furniture on the left side of the room. I might try putting a blanket over it to see if that does anything. I appreciate that suggestion. I've actually got a full length mirror I can stand up in the reflection positions to see where they are from my primary listening position.

I'm not sure acoustic treatment will even be a solution to whatever it is that is happening. I should probably move on with life and just enjoy it how it is. I'm not even sure I want to buy a calibrated mic and start seeing 'problems' that I don't know about. Although, I believe I have seen where there is some ability to manually adjust an EQ in the Denon receiver menus. I'm not sure it gives you control over each channel or not if that even really matters frankly.
 
nathan_h

nathan_h

Audioholic
Since it sounds like one side wall is present and one side wall is not present. That lack of symmetry can mess with your sound stage, imaging, and tone.

The simplest way to increase symmetry in such a situation is usually to place board band absorbers on the wall that is present (six inch thick minimum to cover all the frequencies above the room transition evenly) which makes the wall "disappear" so that side of the room sounds like the open side of the room.
 
ryanosaur

ryanosaur

Audioholic Spartan
The most simple fact to consider is that ALL OF US have less than perfect situations. Even the guys that build out their own dedicated room still have some things to contend with... less maybe, but I guarantee that unless they are dropping a second mortgage to build out an acoustically isolated and perfectly designed Golden Trapagon room (yes, I'm being a little hyperbolic in that, but it makes the point! ;) ) that there will still be issues.
What Nathan added in is a perfect example of how you can do things for free that will help you determine what may be helpful.
I would add, the more willing you are to change things, the more likely you will come out on top. This is especially true with Subwoofers, for example.
No amount of acoustic treatment will fix improper setup. It may help alleviate having a speaker too close to a side boundary as mentioned above, but you also lose some control over what else may be changing.
A 4" thick absorber will pretty much attenuate anything from 500Hz on up. You can combine that into an Ab-Fuser which will scatter some of that energy instead of absorbing everything... but you still don't have complete control.

As long as you are unwilling to post any photos, you are pretty much at the end of what we can offer in way of assistance. My recommendation to you would, *gulp ...be to check out GIK if you choose to pursue this angle any further. They will require specific measurement files from REW to analyze. I do not know if the need to see pictures of your room, or maybe just a floor plan, but they do offer consultation and make recommendations on how to treat your room using their products.

Cheers.
 
F

Fastfwd

Audioholic Intern
Since it sounds like one side wall is present and one side wall is not present. That lack of symmetry can mess with your sound stage, imaging, and tone.

The simplest way to increase symmetry in such a situation is usually to place board band absorbers on the wall that is present (six inch thick minimum to cover all the frequencies above the room transition evenly) which makes the wall "disappear" so that side of the room sounds like the open side of the room.
I wasn't very clear in how I stated that. It is actually the back wall (not the side) that has the 6' wide opening into another room. I heard some guys on a podcast (Hifi Podcast with Darren and Duncan - really good info) discuss how having an opening into another room can actually be a great thing idk.

So, front wall with speakers has a door on the left and then a pretty big window (maybe 6 feet idk) with curtains. The rear wall has a big 6' opening into another room on the right side and a smaller opening more like a doorway size on the other. Not that this makes one bit of difference to clarify it.

Thanks everyone for trying to help. I may check into getting a mic and running REW to see what it tells me. I'm just afraid it will open a can of worms/pandoras box situation. The inbalance of soundstage is my only real gripe currently.
 
Pogre

Pogre

Audioholic Overlord
As mentioned, get a umik mic and learn REW. There's a slight learning curve, but I figured it out anyone can. If you're hearing differences just swapping out cables I think it's fair to say there's a certain level of expectation bias and placebo involved on your part. All the more reason to read up on the subject and learn some more before pulling the trigger on a project like this.

I wouldn't even consider attempting room treatments without a ton of homework or consulting an acoustician. I mean someone who can take a look at a measurement file to get an idea of what's going on in your room. This type of work requires a pretty deep dive to make informed decisions for positive changes.
 
ryanosaur

ryanosaur

Audioholic Spartan
Thanks everyone for trying to help. I may check into getting a mic and running REW to see what it tells me. I'm just afraid it will open a can of worms/pandoras box situation. The inbalance of soundstage is my only real gripe currently.
It may. ;) But unless you succumb to OCD behavior too easily, you'll be fine! :) If you are in fact the type of person who wants to milk the best performance from you rig, learning how to do measurements is handy. To be fair, once you are happy, you may never touch it again until you upgrade or move.
I do not know if you will be able to measure the uncentered soundstage. It is possible a professional acoustician could identify something in the measurements. I don't think I could. :D
 
Pogre

Pogre

Audioholic Overlord
I wasn't very clear in how I stated that. It is actually the back wall (not the side) that has the 6' wide opening into another room. I heard some guys on a podcast (Hifi Podcast with Darren and Duncan - really good info) discuss how having an opening into another room can actually be a great thing idk.

So, front wall with speakers has a door on the left and then a pretty big window (maybe 6 feet idk) with curtains. The rear wall has a big 6' opening into another room on the right side and a smaller opening more like a doorway size on the other. Not that this makes one bit of difference to clarify it.

Thanks everyone for trying to help. I may check into getting a mic and running REW to see what it tells me. I'm just afraid it will open a can of worms/pandoras box situation. The inbalance of soundstage is my only real gripe currently.
I think you might be surprised. Learning how to take measurements and use REW really opened my eyes and did help me figure out what's going on in my room (at least partly, I haven't dug into room treatments yet! :eek:). I think once you start doing the work you'll catch on quick. I was even starting to have a little fun after playing with it for a day.
 
CajunLB

CajunLB

Full Audioholic
I have an iPad 3. I would like to know if I’d buy one of the cheaper Dayton measurement microphones if it’s possiblle to use my iPad to take measurements with a measurement mic and rew with iPad 3! Or do I need a laptop with more power to be able to do this properly?
 
ryanosaur

ryanosaur

Audioholic Spartan
I have an iPad 3. I would like to know if I’d buy one of the cheaper Dayton measurement microphones if it’s possiblle to use my iPad to take measurements with a measurement mic and rew with iPad 3! Or do I need a laptop with more power to be able to do this properly?
Unless something changed, I do not believe there is an App for that. REW will run on Mac or PC, and the required microphones all use Full size USB plugs, last I saw.
Your best bet is to peruse the REW website.
 
F

Fastfwd

Audioholic Intern
I think you might be surprised. Learning how to take measurements and use REW really opened my eyes and did help me figure out what's going on in my room (at least partly, I haven't dug into room treatments yet! :eek:). I think once you start doing the work you'll catch on quick. I was even starting to have a little fun after playing with it for a day.
I have to confess that I've recently contemplated that my sub is probably not integrated as it should be. It has a phase adjustment dial that I've never really attempted figure out how to dial in properly, etc. I'm sure REW would be the answer to where the phase dial should be set for one thing.
 
William Lemmerhirt

William Lemmerhirt

Audioholic Warlord
I have to confess that I've recently contemplated that my sub is probably not integrated as it should be. It has a phase adjustment dial that I've never really attempted figure out how to dial in properly, etc. I'm sure REW would be the answer to where the phase dial should be set for one thing.
A quick and dirty way to experiment with this is play a test tone at the XO frequency, usually 80hz.
Set the master volume to -20 to -30 just so you have high enough volume. With an spl meter(or phone app, I say that with some reticence lol) at the listening position(LP) have someone rotate the phase knob. When you get the most output, that’s where you want it. Might be easier to put the phone on a stand so you can see it from the subwoofer location, if you don’t have an assistant.
 
highfigh

highfigh

Audioholic Overlord
I have an iPad 3. I would like to know if I’d buy one of the cheaper Dayton measurement microphones if it’s possiblle to use my iPad to take measurements with a measurement mic and rew with iPad 3! Or do I need a laptop with more power to be able to do this properly?
You need something with a USB port, old or new. Power has nothing to do with it.
 

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