[Minn Mark]

Thanks berni. I will have to try that  (that is: moving my 3.6's out into the room more).

Mark

[rw@cn]

Thanks berni. I will have to try that  (that is: moving my 3.6's out into the room more).

Mark

That is the first thing I thought when I saw the picture.

[Rclark]

Try the Cardas alignment for planar calculator. I achieved stunning results with inboard tweeters and a little toe-in.

[fivestring]

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring

This calculator ignores room length and according to it, berni`s planars would be optimally placed at a little over 5 feet, which is worse than the theory predicts as minimum for dipoles:

http://www.enjoythemusic.com/magazine/bas/0508/

[rw@cn]

Cardas/Logan formulas are good starting places. Both make adjustments for dipoles. It is also important to get the room adjusted properly, given any restraints such as furniture and other practical reasons. A good guide is "Get Better Sound" by Jim Smith, it contains many good tips.

[josh358]

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring

This calculator ignores room length and according to it, berni`s planars would be optimally placed at a little over 5 feet, which is worse than the theory predicts as minimum for dipoles:

http://www.enjoythemusic.com/magazine/bas/0508/

I've heard that image depth keeps increasing until planars are 15' out into the room, but -- this according to only one source -- not after that. I've never been able to test it myself since I've never had a listening room big enough, but I do know that in whatever room I've had, the further the planars were from the wall, the better the staging and clarity.

My take on this is similar to the one you expressed in an earlier post: the ear determines the size of an acoustical space by judging the relative amplitude and timing of reflections, and if dipoles are close to the front wall of the listening room, the front wall reflections reach the ears before the recorded reflections from the back of the stage. So the brain then gets conflicting cues -- early reflections from a small space and late reflections from a large one -- and reaches some kind of compromise. I've noticed with various setups three kinds of compromise:

- The sound comes forward entirely. This typically occurs when the speakers are very close to the front wall.

- I hear two images -- an image behind the wall, and a faint image at it. This of course is physically impossible but it's what the ear is actually hearing, both the reflections from the listening room wall and the recorded reflections of the rear of the stage.

- I hear an image behind the wall, but not as far back as it should be. This is what I hear under good conditions -- dipoles at least 5' out, listening room wall free of irregularities. And the further I move the speakers into the room, the further back the image goes.

Once the speakers are 15' from the wall, I assume that the room wall reflections are delayed enough so that they no longer arrive before the first reflections on the recording, and you get a better sense of the size of the original acoustic space.

One way of minimizing this in smaller rooms is to use diffusion at the first reflection points on the front wall. Absorption gives you a cleaner sound, but not as much depth. Arguably, absorption is truer to the original recording, but it's often pointed out (including in the second article) that two-channel stereo needs the help of room reflections. If you listen to a pair of speakers outside or in an anechoic chamber, they don't sound very good.

Anyway, the bottom line for me is that Cardas and other formulas position the speakers for bass reproduction. But this doesn't always give you the best imaging, or midrange clarity. I usually find that I end up positioning the speakers for imaging, since bass is easier to fix and, for me, anyway, less important to a sense of naturalism, though I can see that people who don't much listen to orchestral music might want to favor the bass instead.

Another consideration which I don't see mentioned in these formulas is crossover lobing and the rear wave. At the crossover points of dipoles you get sort of a gear or cauliflower pattern in the lateral power response. If you listen on-axis, you don't hear it from the front wave, but if the first reflection of the rear wave is in one of the nulls, it's likely to shift the tonal balance, particularly if the speaker is close to the wall. As the second article points out, the ear is very sensitive to this kind of crossover problem, so the best placement may involve minimizing it, rather than smoothing the bass (which can always be trapped or equalized).

[fivestring]

Great post josh358, I can agree on most everything, I would just like to add that in berni`s room, in the reversed position, even the bass is way better than in the normal position, I`m sure berni would confirm that. Maybe we will measure it some day, soon.

Perhaps It`s not so much about the image depth, but the "image location freedom" in all planes that`s much more convincing and let`s not forget that the image focus should appear just about anywhere, according to where the performers stood during the recording sessions and that includes not only behind the speakers, but sometimes in front and even "at the speakers".

Some people complain that it`s wrong if the sound image emanates directly from the speaker (on some recordings).
I would say that if it was meant that way, then it should be heard (perceived) that way. Of course, if a speaker constantly attaches all images to itself, then this is undesirable, but if, on the other hand image focus of all instruments is constantly way behind the speakers, then this is undesirable too.

At berni`s place I can hear instruments` (or vocals`) image focus all around the speakers, mostly far behind the speakers, sometimes closer, sometimes at the speaker plane and sometimes in front of the speakers.
Many older jazz recordings sound very direct and sometimes the image focus is in front of the speaker - I find the ability of the system to vary the image focus in regard to the recordings very attractive and vice versa, if the system reproduces all images always way behind the speakers - boring.

Another thing regarding the bass is the dreaded upper bass suckout that happens in smaller rooms if woofers are lifted too much from the floor. Actually, the tall planar woofers are sensitive in this regard too, namely, the upper portions of the foil membrane contribute to the level of the overall suckout in the 100 - 200 Hz area.

From my experience this doesn`t happen in larger rooms, or much less likely. Allison wrote a lot about it, see also this interview:

http://www.stereophile.com/content/glorious-time-ars-edgar-villchur-and-roy-allison-allison-part-2

Edit: Beside staging, I consider the biggest improvement in the tone reproduction of the instruments, in this regard conventional setup doesn`t come even close - it`s pure magic!
Sorry, I have to repeat that over and over again...

[Rclark]

Cardas/Logan formulas are good starting places. Both make adjustments for dipoles. It is also important to get the room adjusted properly, given any restraints such as furniture and other practical reasons. A good guide is "Get Better Sound" by Jim Smith, it contains many good tips.

 I used the Cardas planar calculator and achieved simply stunning results in my room, even with my current limitations. I will take it further with room treatment, post mod.

[josh358]

Great post josh358, I can agree on most everything, I would just like to add that in berni`s room, in the reversed position, even the bass is way better than in the normal position, I`m sure berni would confirm that. Maybe we will measure it some day, soon.

Perhaps It`s not so much about the image depth, but the "image location freedom" in all planes that`s much more convincing and let`s not forget that the image focus should appear just about anywhere, according to where the performers stood during the recording sessions and that includes not only behind the speakers, but sometimes in front and even "at the speakers".

Some people complain that it`s wrong if the sound image emanates directly from the speaker (on some recordings).
I would say that if it was meant that way, then it should be heard (perceived) that way. Of course, if a speaker constantly attaches all images to itself, then this is undesirable, but if, on the other hand image focus of all instruments is constantly way behind the speakers, then this is undesirable too.

At berni`s place I can hear instruments` (or vocals`) image focus all around the speakers, mostly far behind the speakers, sometimes closer, sometimes at the speaker plane and sometimes in front of the speakers.
Many older jazz recordings sound very direct and sometimes the image focus is in front of the speaker - I find the ability of the system to vary the image focus in regard to the recordings very attractive and vice versa, if the system reproduces all images always way behind the speakers - boring.

Another thing regarding the bass is the dreaded upper bass suckout that happens in smaller rooms if woofers are lifted too much from the floor. Actually, the tall planar woofers are sensitive in this regard too, namely, the upper portions of the foil membrane contribute to the level of the overall suckout in the 100 - 200 Hz area.

From my experience this doesn`t happen in larger rooms, or much less likely. Allison wrote a lot about it, see also this interview:

http://www.stereophile.com/content/glorious-time-ars-edgar-villchur-and-roy-allison-allison-part-2

Edit: Beside staging, I consider the biggest improvement in the tone reproduction of the instruments, in this regard conventional setup doesn`t come even close - it`s pure magic!
Sorry, I have to repeat that over and over again...

I remember reading Allison's original paper in the AES Journal! I've learned more since about line source woofers -- interestingly enough, the floor and ceiling reflections extend them to several times their length, see page 9:

http://diy-audio.narod.ru/litr/nflawp.pdf

So the issue here is that you still have adjacent-surface interference from the floor and ceiling bounces, but it isn't a problem if the woofer driver is < half a wavelength from the adjacent surface, e.g., if it runs floor to ceiling. On the other hand, you do get cancellation from the front (speaker) wall, just at different frequencies from what you'd get with an omnidirectional woofer, since the phase of the rear wave is reversed. This I think is what causes those annoying nulls in the upper bass region of line source planars, since floor and ceiling are accounted for and there isn't much radiation to the sides. It can be more of a problem than with omnis since the reflections aren't coming from three surfaces, which with proper placement gives you three path lengths that fill in the nulls (though omnis more than make up for that by stimulating more room modes).

The conventional explanation of image depth is that distance is determined by the ratio of reflected to direct sound, and that the size of the space is determined by the relative timing of direct and reflected sounds. But in reality, I think it's more complicated than that, for one thing, the head-related transfer function should be able to determine direction of sounds, and for another, empirically, recording engineers adjust more parameters when they use artificial reverberation. I've found that surprisingly little is known formally about the psychoacoustics, but some interesting progress has been made. I particularly like the table on page 87 here, it explains a lot of what we hear from dipole positioning:

http://tinyurl.com/7ozgjp3

I see for example that it explains why you stop hearing tone coloration when the 20.1's are 17' out, that's just about where it stops happening. It might be even better to have the speakers out a bit farther from that perspective, it looks like it's all gone at about 40 ms. I imagine the same thing could be done with diffusion, if you could get the levels below the threshold -- according to this, that's a bit more than 20 dB down from the direct sound. I wonder if practical diffusors are that effective? Something I have to check into at some point.

My Tympani 1-D's used to do what you mention -- reproduce close miked recordings up by the speaker plane. (They also made them sound huge, which was probably accurate given the geometry but didn't sound right!). Agree that the speaker plane shouldn't be a limit. I've heard some speakers that were notoriously good at creating an image out front, most spectacularly the IRS V. If anything, that image was too spectacular -- it was like a hologram, you felt like you could walk through and around the instruments, which isn't something I've ever experienced in a real concert hall. The IRS was different than any current speaker I can think of in that it was a cardioid. I remember Arnie Nudell saying at the time that that made the best image of any pattern that they tried. (Many so-called omnis have a cardioid pattern at the top, but it isn't consistent as a function of frequency and damages the imaging rather than improving it.)

Not to be cliched or anything, but when it comes to audio, I think space is the final frontier! If you want a blast and you have a symmetrical room, try turning maggies so they're edge on to you, in a "V" that opens away from you. When it works, the effect is fairly amazing -- more like being in a real acoustic space than listening in on one, if you know what I mean. Not only do you entirely avoid double reflections, it opens up the soundstage laterally like crosstalk cancellation, but without the annoying phasiness.

[berni]

Great post josh!

[josh358]

Thanks, Berni.

[Gerner]

Hello Berni

Would you mind to PM me?

Gerner

Here you go Steve.I cant attach pdf-s,so pictures must do.

[SteveFord]

You need 3 posts to be able to receive a PM - it's to keep out spam and nut cases.
One down, two to go...

[berni]

I have no problem to send you the drawings, just in case you will duplicate them and sell in hundred of pcs. you should send a nice present box.. 

[Gerner]

You need 3 posts to be able to receive a PM - it's to keep out spam and nut cases.
One down, two to go...

Thanks Steve.

Didn't know... Anyways.. I copied the wonderful stands and made CAD drawings. They are now under production.

 

[Gerner]

I have no problem to send you the drawings, just in case you will duplicate them and sell in hundred of pcs. you should send a nice present box.. 

Many thanks for your kindness Berni... Mine will be exactly like yours. CNC, powder coating.

 

[Gerner]

And just for the peace in mind.

I'll make this pair in one sample only. No interest in commercializing them.

 

[berni]

Thanks Steve.

Didn't know... Anyways.. I copied the wonderful stands and made CAD drawings. They are now under production.

 

You already  copied them? Was everything visible on this pdf?
I could send you the original dwg..  if I had your email.

[Gerner]

You already  copied them? Was everything visible on this pdf?
I could send you the original dwg..  if I had your email.

I made new CAD drawings based on the design you made. I took measures on my own pair of 20.1's, and happily your pdf showed here was good enough that I could do quite as you did. Also the pics you have shown was a very good help.
I am living in Serbia and I have got some quotes from local companies... but it is generally difficult to find companies here that poses big enough CNC machines to cope with the vertical parts.

We can exchange CAD files and I did mine ( No I didn't. I friend of mine did  ) in Google Sketchup generating a .skp file.

It would maybe be valuable to 20.1 owners to know about the costs for having the complete job done. I am not sure if you aprove such a suggestion?

I wished for some years to make such stands myself. The commercial available stands are not in the class of yours and neither they look that good. Accidently I saw this post from you by googleing and got inspired to get on right away.

It is beyond any doubt the stands will lift the 20.1s into a different class of fidelity.

You may PM me for exchange of experience.

Now with email: gernerdotchristensenatgmaildotcom

[berni]

Actually I am from Slovenia and not far away... 

Will send you the files, when I get to my office again.(tommorow)

A hint for the large part. Make a hole for centering the piece and you can move it to access it with a machine which is limited.