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Old 4th January 2013, 09:30 PM   #61
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That's my old one. But as shown in my other measurements, I overlayed 3, and they're all fairly similar. And that was before my dustcaps got smooshed

New ones are doing great
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Old 4th January 2013, 09:39 PM   #62
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Quote:
Originally Posted by tuxedocivic View Post

By 10khz the response is down 5db at only 5 degrees off axis! So what do you think is going to happen when you introduce a nearly omnidirectional tweeter around 10khz? It's going to spray sound all over the place and fill in all that sound that is missing off axis.

Now move back on axis. You have nearly flat response with the EL70, plus all the extra ouput of the tweeter. That's going to sound to bright.

Just beware.
Which is yet another reason why an upfiring or backfiring tweeter makes so much sense.

But, I am curious; at what distance were the on-axis/off-axis tests conducted? If they were at the 1" distance you recommended in another thread, it seems there might be more physics at play to skew the results than plain old "beaming".

The reason I say this is because my dual EL70 microTowers do not sound anything like your graphs look, if that makes any sense. Perhaps this is due to the fact that my speakers are in the "Castle' configuration (one driver firing up, one forward).

Either way, I do not find that there is much difference at all in the high end whether I am perfectly on axis with them (via appropriate toe-in of each) or standing in the adjacent dining room. Laid-back, rolled-off highs is just the way they are.

For close to 18 months, this has been fine for me. Lately I've noticed, however, that cymbals and such just don't have the "presence" that they should (again, regardless of the orientation of my ears to the drivers).

With the upfiring tweeters, the presence is there.

Last edited by cogitech; 4th January 2013 at 09:44 PM.
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Old 4th January 2013, 09:47 PM   #63
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I said measure at 1" to get a nearfield measurement. The measurements I've posted were at 1m distance. Maybe 0.8m because I was indoors for these and a small single driver can be measured at 0.8m without any issues.

It's likely related to your castle configuration that you're not hearing what I'm hearing, because I've found them to behave like this since the first time I have the EL70 at home (Dave lent me a couple pairs quite some time ago). I am accustomed to high dispersion designs though. Lately I've been doing controlled directivity designs, and the beamyness of the EL70 is less noticeable.

I however disagree this is a reason to use upfiring/rearfiring tweeters. Those just spray sound everywhere we don't want them to. I could write a page about why that's a bad idea. Admittedly though, I've never done it.
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Old 4th January 2013, 09:56 PM   #64
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Quote:
Originally Posted by tuxedocivic View Post
I said measure at 1" to get a nearfield measurement. The measurements I've posted were at 1m distance. Maybe 0.8m because I was indoors for these and a small single driver can be measured at 0.8m without any issues.

It's likely related to your castle configuration that you're not hearing what I'm hearing, because I've found them to behave like this since the first time I have the EL70 at home (Dave lent me a couple pairs quite some time ago). I am accustomed to high dispersion designs though. Lately I've been doing controlled directivity designs, and the beamyness of the EL70 is less noticeable.

I however disagree this is a reason to use upfiring/rearfiring tweeters. Those just spray sound everywhere we don't want them to. I could write a page about why that's a bad idea. Admittedly though, I've never done it.
There seem to be as many people who feel front-mounting a tweeter with a fullrange is a much worse idea than back-mounting it. Pit Hinder's explanation makes a lot of sense to me. The point is not necessarily for the tweeter to handle the entire upper portion of the spectrum (as in a true multi-way design) but to simply supplement. Back-firing (and top-firing, it seems) allows one to do this without the corresponding time domain issues of overlapping a full range and a tweeter in a traditional manner. The "air" is there, but without the negative effects. The full ranger is still providing pretty-much everything, so imaging, sound-stage, etc. remain.

At least the way I have deployed it, the change is very subtle and inconspicuous, but immediately obvious when disabled.

BTW, I did try rear-firing the tweeters last night for a brief time and I found it unpleasant (relative to up-firing, which is completely non-fatiguing). Perhaps I should have reversed polarity on them in that configuration. I don't know...

Last edited by cogitech; 4th January 2013 at 10:00 PM.
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Old 4th January 2013, 10:15 PM   #65
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More anecdotal mumbo-jumbo, of course, but I should tell you something that happened last night.

I've played Patricia Barber's Cafe Blue (88.2, 24-bit) dozens of times. Last night I am sitting there beside my wife appreciating the liveliness of the cymbals and the tapping of the sticks on the edges of the drums, etc. and I look over at my wife and she is sitting there playing "air drums", tapping the imaginary drum sticks on the cymbals, etc.

This is extremely out of character for her! So I sort of laughed under my breath and she glanced up at me.

"Who is this? Is this new?" she said.

"No, you've heard it dozens of times... You're just hearing it differently."

"Oh, those twitters things?" (She's Japanese)

"Yes, dear. The twitters."
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Old 4th January 2013, 10:22 PM   #66
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I personally don't agree with the super tweeter concept in general. IMO, the EL70 is a one man show. No help up high or down low. That's what it's good at. That doesn't mean it's perfect. But if you need one driver that does it all, this is it.

As for up firing, Pit Hinder's explanation of time domain would conclude that up firing is a bad idea. There will be some direct sound, albeit delayed from the full range drivers sound. Because you have experienced the up firing to be better, then it may be reasonable to conclude time isn't the issue. When you up fire, you fill in the off axis, but at a time delay. That's my problem with it. There is likely major nulls in the response that aren't audible, but it's missing information. So it should be audible.

As for the castle configuration, the reason it works, is because it's not omni above about 2khz. If it were, then it would also be bad. Even so, I believe there is likely a null around 1khz due to the offset. Probably not so bad though, and the advantage of baffle step compensation and higher dynamics outweighs what ever little driver interferance there is.

When you rear fire, you are not getting any sound other than reflected sound off the rear wall, which is likely around 10msec delayed. Ok, fine, but why do we need reflected sound from the rear wall? Will that add spaciousness? I doubt it.

EDIT - Have you tried front firing? What tweeter are you using? If it's the ERT26, I doubt it's putting out much of anything above 8khz at a 90degree angle like that. Most treble we hear is in the <8khz range anyways.

The few rear tweeters I've heard were on commercial speakers and I didn't like them at all. But I wasn't privy to the design details, so maybe they were just crappy speakers. If I had to choose between up or rear firing, I'd take rear firing. But again, I'm just talking theory here, I've never tried to do it.

Last edited by tuxedocivic; 4th January 2013 at 10:24 PM.
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Old 4th January 2013, 10:34 PM   #67
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We are at odds because I have zero theory but I have actually tried it and I like what I hear.

I think there are simply too many variables to consider in the real-world applications of loud speakers, which pushes the final implementation firmly into the realm of art as much as science.

In an anechoic chamber, all of your theories would "ring true" I think. With all the other variables involved, including luck, I find it less than surprising that a pair of 1978 Sansui tweeters stuck on the top of my microTowers adds something very wonderful to my experience of the music I listen to. But that's the way I usually roll. I just try sh!t. Sometimes it works, sometimes it doesn't, but I usually break all the rules one way or another.
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Old 4th January 2013, 10:58 PM   #68
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You're right, we're at odds. But I don't disagree you probably get a lot of enjoyment out of your added tweeter. I just don't think it's because of additional top octave output
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Old 4th January 2013, 11:02 PM   #69
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I didn't create this thread to start an argument, but I take on board everyone's point of view. I've ordered the tweeters and caps, 2 x 1uF and 2 x 0.33uF. This will give me the 20KHz cross over point for the tweeters. I will experiment, by placing them facing in different directions and see what I prefer. I'll post my finding when my parts turn up.

Thanks again for the help with the sizing of the components.
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Old 4th January 2013, 11:24 PM   #70
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Guys,

Do what gives you the greatest emotional connection.

I just finished wiring drivers in a box that would fir this discussion. MicroTower II inspired bipole microTowers with CHP70.2eN and ERT26eN on the previously unused faces. CHPs wired for 4 ohm, ERTs wired for 16 ohm with 1.8 uF series cap.

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