[zybar]

The plants look nice, but how much diffusion are they really doing?

Ethan or Bryan, care to comment on plants diffusive properties?

George

[Jason Jones]

How, pray tell, do D1s mount horizontally?  I think I'd have to get some after-market hardware and get creative with hanging picture wire.

Countersunk holes are provided on the top and bottom (assuming the ribs are running down). To mount horizontally you can: 1) Hang horizontally and drill holes (I know this sounds frightening, but works fine - the material is not brittle) 2) Mount the provided furring strip vertically (and screw in as you would if it were horizontal) then add another furring strip for the other side (so all 4 screw holes would be used).

OH, BTW matte paint does make the D1's look nice!

Jason

[Jason Jones]

Hi Jason,

Thank you for sharing your vast knowledge!  I really like the GIK D1s--I just primed and painted them to match my apartment--and I'm curious what else I can do.  I remember someone saying that I could add mass in the diffusion cavity to improve rigidity and bass absorption.  What are your thoughts on doing so?

-- Nils

Adding acoustic cotton to the cavity will help with bass absorption. I would recommend the 3.5" bonded logic. They have a search on their web-site for local distributors: http://www.bondedlogic.com/search.aspx

Jason

[Housteau]

The plants look nice, but how much diffusion are they really doing?

Originally I just had the plants there because they looked nice.  Then, a few years back I started to notice small changes to the sound of my room as I moved them about.  I don't believe they are very good diffusers compared to ones engineered to be such, but they do enough for my circumstances.  My guess is that just the higher frequencies are being redirected.  Whatever is actually happening, I am able to better control the center image and focus with them being there with these speakers.

[Jason Jones]

As for my room... well, it's 17' x 22'.  For my livinig room space, I have a 12' x 17' section with a partition of varying height between the right speaker and the kicthen.  A pseudo-sidewall, if you will.  Maggies are 4.5' out and 1.5' from the side walls.  Pictures would be best.. perhaps when I get home.

-- Nils

Here is a simple sketch showing some of the "best" places for diffusers (meaning where people like to have reflections come from). It is the area that is (from the reference point of the listener) 40-140 degrees from the speaker (or soundsource).



http://www.audiocircle.com/index.php?action=gallery&pos=0

Hopefully either the link or image will work. I am having some image posting difficulties

[woodsyi]

Jason,

I can't make sense of the picture.


Would you please elaborate.

[ooheadsoo]

The green lines split the room into quadrants, which can be ignored in this context.
The purple lines are what we're looking for, subdividing from the listening spot.
The largest 2 areas, demarcated in purple but labelled "40-140 deg" and "Ideal" in red are the sections that Jason is saying most people prefer the diffusion to be placed.
The degree demarcation is 0 degrees starting from the bridge of your nose to the tweeter or other acoustic center of your speaker and then sweeping outward from that line.
The rest should be self explanatory from this point.  I think it would have been easier to understand without the green lines and even the red lines 

[woodsyi]

OK, I get it.  Why is that center back behind the listening is not ideal?  Also, don't the early reflection points fall right on or inside the 0-40 degree line which would make it bad for diffusers being employed on early reflection points?

[ooheadsoo]

Maybe for first reflection, the time component of the reflection is still too early, and so it is more important to absorb rather than diffuse.

[woodsyi]

There seems to be slight difference of opinion between Jason and Ethan in terms of effectiveness on reflection point diffusion.  I also wonder if the most effective position(s) of diffuser(s) on the back wall would vary with speaker toe-in angle.  I will have to experiment with different arrangements and see if I hear any difference in my room.  This is why AC is so great.  It never fails to give me tweaks to try. 

[bpape]

Part of the deal with the rear wall is because in many cases, it's better to absorb and kill a big null off the rear wall that is apparent in many rooms.  The other issue is that in many rooms, you're simply not far enough away to make it effective down into the vocal range.

Again, he is showing here what 'most people prefer'.  I personally design a lot of rooms (especially studio control rooms) with interspersed minor absorbtion and diffusion on the rear half of the side walls.  There is a definite increase in spaciousness of the portion of the soundstage that is not in front of you and a definite reduction in a lot of nasty 'zing' and 'slap' (sorry for the technical terms  ).

Just my 2 cents.  Jason has probably forgotten more about diffusion than I'll ever know.  I just know what works in practical implementation, what each can do for you, etc.

Bryan

[Jason Jones]

Jason,

I can't make sense of the picture.


Would you please elaborate.

I think ooheadsoo got it mostly, if not entirely right. Here are the rules for interpreting my messy picture:

1) The green lines mean nothing.
2) The red lines mean nothing - just the words.
3) The round thing is a listener and the rectangles are speakers.
4) It is the triangular spaces made by the purple lines that we are intersted in.

This comes from research - Floyd's Summer 06 AES paper has a great summary. These areas (40-140 degrees from the source) where research shows that people like reflections to come from. Audible reflections coming from nearer the speaker (or near 180 from the speaker) tend to make the sound worse.

So, this is really where good and bad audible reflections come from - but, that does, in my opinion, translate into diffuser placement.

Jason

[Ethan Winer]

There seems to be slight difference of opinion between Jason and Ethan in terms of effectiveness on reflection point diffusion.

Indeed. When I tried diffusion at the side-wall reflection points it was much worse than absorption. The better imaging and pin-point focusing of sound sources with absorption at those places disappeared when I used diffusion.

--Ethan

[Ethan Winer]

Ethan or Bryan, care to comment on plants diffusive properties?

I can't imagine plants would do anything useful because they're not heavy and massive enough to be "visible" acoustically. Except maybe around 10 KHz.

--Ethan

[bpape]

I think if you look at Jason's plot, that the side wall reflection points would in most cases not be in the 40-140 degree 'optimal' area.

Bryan

[zybar]

There seems to be slight difference of opinion between Jason and Ethan in terms of effectiveness on reflection point diffusion.

Indeed. When I tried diffusion at the side-wall reflection points it was much worse than absorption. The better imaging and pin-point focusing of sound sources with absorption at those places disappeared when I used diffusion.

--Ethan

I never tried Ethan's diffusion panels where Jason is suggesting, but I can absolutely say that they work very well directly behind my listening position (which is greater than six feet away) as per Ethan's instructions.

George

[Nils]

Here's what I've got working so far.  I find that the 244s at the first reflection points between the speakers work wonderfully.  I moved the speakers farther out (5.5' apart) and reduced toe-in, and everything sounds so much more natural.  I'm very happy so far.



Two things I'm definitely considering:  stacking an additional tri-trap to treat the entire corner and definitely getting stands for the 244s.  It's been a huge process to get those D1 panels mounted so perfectly, and I really don't want to move them for now.

-- Nils

[Jason Jones]

There seems to be slight difference of opinion between Jason and Ethan in terms of effectiveness on reflection point diffusion.

Indeed. When I tried diffusion at the side-wall reflection points it was much worse than absorption. The better imaging and pin-point focusing of sound sources with absorption at those places disappeared when I used diffusion.

--Ethan

I never tried Ethan's diffusion panels where Jason is suggesting, but I can absolutely say that they work very well directly behind my listening position (which is greater than six feet away) as per Ethan's instructions.

George

A few points here:

1) To be a problem, the reflections need to reach the threshold of audibility.
2) Early sidewall reflections are usually in the "bad" area of the sidewall.
3) Early sidewall reflections also usually come sooner than back wall reflections and thus have more "zip".
4) Early sidewall reflections also suffer if your speakers off-axis performance is not flat, with any toe in early sidewall reflections are going to be "really" off-axis.

Jason

[Daygloworange]

4) Early sidewall reflections also suffer if your speakers off-axis performance is not flat, with any toe in early sidewall reflections are going to be "really" off-axis.

A very good point. A lot of speakers suffer from terrible off axis response, and the early reflection points from side walls bounce that portion at you, mixed in with the really good on axis response. Add in the effects of comb filtering when two wavefronts collide, and you can easily see how important side reflections really become.

Cheers

[Housteau]

I can't imagine plants would do anything useful because they're not heavy and massive enough to be "visible" acoustically. Except maybe around 10 KHz.

It surprised me too when I first started to notice a difference with both my Infinities and Martin Logans.  The change happened when I positioned them behind the speakers, instead of just having them off to the sides.  Then, with my new system I have been able to use them in the same way to help flesh out the center images.  It must be a dipole thing.  I recommend that dipole owners give it a try.  There is very little cost involved and so much to be gained.  Most homes probably have one or two in other rooms that can be borrowed for a test.  I have heard from others that swear it has worked for them as well.  Just be sure that the plants are large enough.  Although I have not tried them, I would think the standard artificial ficus tree would work just fine. 

If it is just all in my head, well, that is where the music ends up anyway .