[Letitroll98]

Another month, another set of changes and observations and another post. Still persisting with the long-wall set-up. Current set-up sees the speakers 2.20m apart and listening position 1.85m from each tweeter - as per the Audio Physic model for long-wall speaker set-up.

Interesting, as a newcomer here I thought it best to read from the beginning of the thread and was thinking, "Why doesn't he try placement along the long wall and the Audio Physic method?"  Your imaging is improved because you increased the time between direct arrival sounds from the speakers and early reflections from the side walls, which was obviously your problem to begin with.  Concurrently I read the Master Set thread http://www.audiocircle.com/index.php?topic=64321.0 which looks like a slightly different procedure for getting to the same place.  Seems to have some good info and I'll try it along with Cardas and Audio Physic when I get my new room set up.  As noted in the Master Set thread, no one placement or method is gospel for all situations, having all the info available helps when dealing with a difficult placement situation like yours.  Good luck.

[zydeco]

Letitroll98

Yes, the long-wall set-up has resulted in a significant improvement. One downside seems to be that sitting close to the rear wall resulting in the a cancellation frequency that is quite high - about 165Hz in my case. My hope is that I can treat the rear wall near the listening position (assuming that I'm right about the cause) but I'm not sure how much of the rear wall needs to be treated. All good fun in that I've got much better sound and am learning a lot from all the contributers.

Regards,
Zydeco

[bpape]

A better and cheaper solution would be to just not sit all the way back by the wall   

Bryan

[zydeco]

Bryan

A good idea, of course. The main issue is that having speakers and chair away from the walls creates an odd space given the 12' length (in the long-wall set-up). I guess, though, that if I could get a little extra distance so that the cancellation frequency is <100Hz. If I was to treat the rear wall then should I just treat the area behind the listening position or is there benefit in treating other areas of the rear wall?

Regards,
Zydeco

[bpape]

If you can move it, I'd try a measurement in the new ear position and see how it impacts the cancellation.  That will tell us if it's primarily a function of the distance to the wall behind you.  Most likely, in any case, the wall behind the seating position directly will be something you'll want to do.

Also, have you tried moving your speakers forward or back say 6" or 12" and see if the 100Hz problem changes?  It could also be partially a boundary cancellation in which case treatment behind the speakers would be helpful.

Bryan

[Letitroll98]

And you can try the full Audio Physics method of placing the listening seat directly on the rear wall.  Sometimes suggested with a bit of damping behind the head.  This reduces the time for early reflections from the rear wall to nearly zero (not completely as you do have a head in the way before you get to your ears  ).  A very different soundstage emerges than what you are used to, you may or may not like it.  But it costs nothing to try.   

[zydeco]

Several weeks have passed but the small room journey continues. I've tinkered with the location of the speakers, chair and bass traps. The latest REW sweep is shown below (with no smoothing) and, all in all, the bass is a lot better. Main issues are at 40Hz, 160Hz and 470Hz which I believe are due to reflections off the front wall, rear wall and floor. This conclusion based on the fact that the estimated and actual path lengths for these frequencies correlate and moving speakers towards front wall leaves the 160Hz null unchanged while changing frequencies of the lower / upper nulls. I see this understanding a big deal as it's allowed me to target the room treatment with, specifically, treatment on the rear wall acting to reduce the 160Hz null. Thanks Nyal et. al. who have helped with this understanding.




The other main change has related to the speaker / listener triangle. My initial long-wall set-up followed the Audio Physic model with an isosceles triangle in which the distance between speakers was greater than then distance from the speaker to the listener. Speaker toe-in was such that apex of the triangle was about 20cm behind the listening position. This set-up gave a good sound-stage and centre image but with some recordings it seemed as though music was coming from the speakers. This effect was dependent on the recording and I'm wondering if it related to recording with multiple microphones.

So, then, I've moved the speakers closer together to form a more traditional equilateral triangle set-up with toe-in such that the apex of the triangle is at the listening position. This set-up seems to have solved the issue in which music comes from the speakers but at the expense of a slightly closed soundstage. My plan is to tinker with the speaker / listener triangle a little more over the next few weeks to see if I can get the best of both worlds. The next attempt will involve the full Audio Physic set-up (with chair against the rear wall) but this will take quite a lot of time to sort-out the furniture. All other suggestions welcomed

Zydeco

[bpape]

That's actually VERY good unsmoothed, in-room response. You're essentially +/-3 from about 45 to close to 400Hz.  Yes - there are a couple of dips that we still need to address.  IMO, the 40'ish one isn't going to be solved by treatment. That to me looks like a natural roll-off of the speaker coupled with a small room issue. Even if you could address the room issue, you're still going to be down most of what you are now at that frequency.

Bryan

[bpape]

That's actually VERY good unsmoothed, in-room response. You're essentially +/-3 from about 45 to close to 400Hz.  Yes - there are a couple of dips that we still need to address.  IMO, the 40'ish one isn't going to be solved by treatment. That to me looks like a natural roll-off of the speaker coupled with a small room issue. Even if you could address the room issue, you're still going to be down most of what you are now at that frequency.

The 400ish may actually be something in the room itself causing a cancellation rather than something to do with positioning.  I'd concentrate on the 150ish.

Bryan

[zydeco]

That's actually VERY good unsmoothed, in-room response. You're essentially +/-3 from about 45 to close to 400Hz.  Yes - there are a couple of dips that we still need to address.  IMO, the 40'ish one isn't going to be solved by treatment. That to me looks like a natural roll-off of the speaker coupled with a small room issue. Even if you could address the room issue, you're still going to be down most of what you are now at that frequency.

Bryan

You're right, Bryan, I've done an (in-room) measurement 5cm from the woofers and confirmed that these start to roll-out around 35Hz. Since the last post I've continued to tweak speaker and listening positions as well as room treatment with a goal of improving bass response while reducing amount of treatment. The reason for this goal is to make sure that the room isn't too dead and is a good visual environment in which to listen.

The result of this tweak-measure-listen process has been a confirmation that treatment for the rear wall reflection behind the listening position can be small in area but needs to be deep enough to cater for the longer wavelengths. It turns out that the cupboard / bookcase (see below) which proved to be an issue in the short wall set-up have proven to be an advantage in the long-wall set-up. The reason is that re-locating the listening chair such that it butts up against bookcase creates a 2.5' deep effective bass trap with further improvements via stuffing the cupboards at the bottom of the bookcases with acoustic foam.

Also, I've moved the main speakers (>80Hz) onto speaker stands and then moved the woofers (<80Hz) around the room to get the best performance. It was possible to get a good measurement at a range of locations but, after extended listening, have found that having woofers located away from main speakers was disconcerting with music with lead-edge bass as the woofers could be localised. Another interesting finding is that my woofers were best located just ahead of the main speakers which, I guess, relates to the acoustic centre of the drivers being at this location.

End result of all this tinkering is that I've been able to further improve the 20 to 500Hz frequency response (although it continues to roll-out around 35Hz) with much less treatment. My impression from listening to much music is that the bass is now much more subtle in that it's both more tuneful and less intrusive but still provides the foundation for the music.

Major downside of the arrangement is that whilst the (high-back) chair does wonders for bass response it does deaden the dynamics. An increase in the gain (within the active cross-over) for the tweeter isn't the solution as this draws attention to (near-field) speakers. I'm thinking of starting to tinker with a) some kind of contraption to make the ambient ribbon tweeters which fire upwards a little more directional and b) some kind of leather / vinyl / plastic headrest that creates a little more reflection. All and any ideas are appreciated.


Regards,
Zydeco

[jimdgoulding]

The thing about long wall placement in your room is that it appears that you must sit with your back against the wall behind you or nearly so.  Your speakers are out from the corners in this case, yes, but not very far out from the wall behind them.  To take 2D to 3D, I think you should at least try this . . . Early on and using the short wall in your room, your speakers were too near your room corners and the wall behind them.   Again using the short wall, from the centerpoint of your tweeter, place your speakers 3' from the walls beside them, not from the bookcase, from the actual walls, and 4 and a half feet from the wall behind them.  Maybe 5' cause of the fireplace.  Let's remove the covers from your fireplace (your fireplace is a natural diffusor).  And leave your bookcases on the sides of the walls in the other end of the room.  We can deal with that later.  This will make your speakers 6' apart, tweeter to tweeter.  Now I know what you're thinking, but bear with me.  Your stage will expand or narrow depending on where you sit and listen.  Sit at the apex of a 6' equilateral triangle plus 3" to the legs between you and your tweeters and toe your speakers in to where you can see a small portion of the insides of your cabinets.  Move that chest out of the picture, nothing between you and your speakers.  Play some acoustical music with percussion and a female vocalist who is centered.  How's it?  Now, lean your head forward in increments of 1" at a time.  Your virtual stage will likely recede in increments.  However, just as likely it will exponentially expand in dimension.  How's it now?  Somewhere in those 3 inches is the third dimension.  You could, after having listened at some length, begin to make your triangle larger in small increments but keeping that relationship in tact.  Or smaller like mine.  No one should laugh without having experienced it for themselves.

Part 2 coming shortly.

Think at that distance your drivers won't coalesce?  Because your mid and high frequency drivers are mounted the way they are (like mine) and because the cabinet that houses them is narrow (like mine), I don't think that will be an issue.  Think the sound will be too aggressive?  Guess what, your speakers will be quiet as sources.  The front end of your room will be populated with the instruments themselves freely appearing in accord with what was intended by the sound engineers.  Use your volume control to set your perspective on the recorded event.   

You will be getting less room interaction and that will reveal more about the acoustics in a recording.  Some recordings don't have real acoustics but imaging will become more focused and palpable and dimensionally real.  It's where you sit in relation with your speakers that makes this more achievable.  And where your speakers sit in relation to the walls around them.  You can move your bookcases back and see/hear what happens- I believe you said one has doors- however, it wouldn't surprise me if that will be detrimental to the relationship and the result I think you're after.

Your speakers are physically larger than mine but they are configured similarly and our rooms are the same width.  Once you get things placed, you may have less need of room treatment, IME, except, perhaps, for lowest bass.  Like to hear about what you experience.  Rooms can even enhance what's in our recordings when the relationship is right, first.

[jimdgoulding]

Oh, yeah, and you won't be wanting or needing a high back chair .

[zydeco]

Jim

Thanks. Current set-up is seen below and has speakers about 5'6" from the front wall and listening position about 2' from rear wall. This gap to the rear wall is filled with listening chair (an old high-back chair), some acoustic foam and then books in the shelves. The bass performance is very good and all my measurements seem to confirm that this is in part because the rear wall reflection is so severely damped (hence the addition of acoustic foam behind chair) and the location of the main speakers need the middle of the room.





So, yes, it's a near-field arrangement with the speakers 5'6" apart and 5' from the listening position. I was concerned about driver-integration but it's not been an issue in most tracks. The speakers seem to be invisible for most tracks (i.e., cannot hear speaker even when looking directly at the speaker) and sound-stage is wide / high. That said, on some tracks I can hear the speakers and the soundstage is distorted so the further changes are needed.

Your recommendation seems to be to move the speakers so that the distance between the speakers is less than the distance from the speakers to the listening chair.  I've always liked this type of set-up when speakers are in a standard (not near-field) set-up but not pursued in this setup as it'd either be a very small triangle or see the speakers move towards the front wall (thus reducing bass performance). That said, I'll give it a go in both the long- and short-wall set-up and report back.

My other issue remains that whilst the high-back lounge chair is a wonderful bass trap it means that the listening position itself is a little dead and system robbed of some dynamics. I've found, for example, that voices sounds natural around the room but tonal character changes a little at the chair and that large orchestral work lacks a little dynamics. The replacement of the chair isn't an option right now so I've put a 1/4" thick rubber matt as a temporary headrest which has given some improvement. Any other ideas? 

Regards,
Zydeco

[jimdgoulding]

Wow, Z, you ARE doing some experimenting in there aren't you?  Wish I could have a listen tho your words are pretty telling.  I had no idea your speaks were as far from the wall behind them as they are.  That's just about what I would do only I'd rotate the triangle around so it was in the length of the room rather than the width so you don't have to sit with your back near a wall.  I'd begin with an equilateral triangle with 5'6" legs like what you already have, more or less, with your room size and with the front of the speaks 5' off the wall behind your fireplace and make incremental adjustments from there.  In my set up in my 12'3" by 14'9" room my Meridians are 60" apart tweeter to tweeter and 61.5" to my ears and 54" off the flat wall behind them.  It's like a concert hall in here and I get to pick my seat.  I know you were set up in the long end of your room first but I'm pretty sure what you've discovered will translate and your room and fireplace will be more useful.  Waveforms may like it better, too.  Keep me and us posted.  Cheers

[bpape]

I would agree with rotating the room for the reasons Jim described.  Depending on the speakers themselves, I might not have that much room behind the speakers to pick up a little boundary reinforcement in the bottom end.

Bryan

[Ethan Winer]

I would agree with rotating the room for the reasons Jim described.

Agreed +1. The speakers would be at the bottom of the drawing facing up, firing toward the fireplace which would then be in the rear of the room. I have a similar arrangement, but I don't use my fireplace. So I packed it full with fluffy fiberglass to make a bass trap, then covered the opening with "brown box" cardboard.

--Ethan

[jimdgoulding]

Ethan-  Hi.  I think Z may need to keep his desk so he would have to put the speakers in the end of the room with the fireplace else he would have to put his desk on a side wall.

I just noticed the placement of the door.  I guess that's gonna make getting the bookself out of that end of the room impossible.  Fudge.

[Ethan Winer]

A desk along a side wall is not a big problem as long as it's behind the listening position.

--Ethan

[zydeco]

Wow, Z, you ARE doing some experimenting in there aren't you?  Wish I could have a listen tho your words are pretty telling.  I had no idea your speakers were as far from the wall behind them as they are.  That's just about what I would do only I'd rotate the triangle around so it was in the length of the room rather than the width so you don't have to sit with your back near a wall.  I'd begin with an equilateral triangle with 5'6" legs like what you already have, more or less, with your room size and with the front of the speaks 5' off the wall behind your fireplace and make incremental adjustments from there.  In my set up in my 12'3" by 14'9" room my Meridians are 60" apart tweeter to tweeter and 61.5" to my ears and 54" off the flat wall behind them.  It's like a concert hall in here and I get to pick my seat.  I know you were set up in the long end of your room first but I'm pretty sure what you've discovered will translate and your room and fireplace will be more useful.  Waveforms may like it better, too.  Keep me and us posted. 

Yes, after having set-up for "room aesthetic", I've been pushed into experimentation which has proven a great experience with substantial improvements in music. All this is the result of the encouragement and ideas received from this community. Thanks again. So, the basic idea is that the near-field set-up will minimise sidewall interactions in the short-wall set-up while the learning on chair / speaker / treatment placements to optimise bass performance will yield even better results given the extra distance. Makes sense.

Agreed +1. The speakers would be at the bottom of the drawing facing up, firing toward the fireplace which would then be in the rear of the room. I have a similar arrangement, but I don't use my fireplace. So I packed it full with fluffy fiberglass to make a bass trap, then covered the opening with "brown box" cardboard. --Ethan

Ethan-  Hi.  I think Z may need to keep his desk so he would have to put the speakers in the end of the room with the fireplace else he would have to put his desk on a side wall. I just noticed the placement of the door.  I guess that's gonna make getting the bookself out of that end of the room impossible.  Fudge.

What is the advantage of locating the speakers to fire towards the fireplace (as opposed to firing away from the fireplace)? The most natural set-up is, as Jim suggested, due to the location of the door and desk but if the advantage is significant then I might just be able to get away with this set-up. I'm not sure if it's relevant but the fireplace is used intermittently so I'm able to treat the fireplace if the treatment can be simply removed when required. An initial attempt at this involved a 0.5" plywood board cut to size to seal the gap with some thick acoustic foam on the outside.

Regards
Zydeco

[jimdgoulding]

Question:  What advice would you offer someone beginning to assemble a system?

Answer:  You can't put a great system in a bad room.  The room is a component you've got to think about.

Asked by Neil Gader of TAS in the October 2010 edition and answered by Frank Van Alstine, pres and designer of Audio by Van Alstine, the subject of NG's Back Page.

The room is an equally important component to an optimally working music system.  Then ya gotta do what Zydeco is tryin to do.  Integrate the thing for the best realization of how your speakers are designed to deliver the music (waveforms) into the room and to your ears.  Where do you put your speaks and your hiney, in other words.  Treat as may be needed subsequently.