Siegfried discovers added dimension

rick57 · « **on:** 28 Jan 2007, 10:13 am »

http://www.linkwitzlab.com/orion++.htm

johnk... · « **Reply #1 on:** 30 Jan 2007, 11:23 pm »

Nothing new. http://www.musicanddesign.com/F_and_R_tweeters.html

Rear tweeters have been a around for many more years that I care to remember.

wikin · « **Reply #2 on:** 31 Jan 2007, 04:05 am »

Hi JohnK,
Perhaps I have not been attentive enough, but why is it that you didn't consider the Neo3pdr to be a strong candidate for your design which provides dipole response for the >1khz region?

cheers.

konut · « **Reply #3 on:** 31 Jan 2007, 04:42 am »

Excellent question! I'm curious as to why more designers don't use a rear firing or dipole planar tweeters especially given the dispersion patterns of most domes, or any tweeter for that matter, as frequency rises.

JohninCR · « **Reply #4 on:** 31 Jan 2007, 05:09 am »

My guess would be because of the unequal polar and frequency responses front and rear for the mid driver, making the XO for the rear tweeter different than the front.

gitarretyp · « **Reply #5 on:** 31 Jan 2007, 05:27 am »

Quote from: wikin on 31 Jan 2007, 04:05 am

Hi JohnK,
Perhaps I have not been attentive enough, but why is it that you didn't consider the Neo3pdr to be a strong candidate for your design which provides dipole response for the >1khz region?

cheers.

I can't speak for John, but the Neo3pdr doesn't perform as well in dipole mode. Now, using two tweeters back-to-back sounds interesting.

wikin · « **Reply #6 on:** 31 Jan 2007, 05:42 am »

I can't speak for John, but the Neo3pdr doesn't perform as well in dipole mode. Now, using two tweeters back-to-back sounds interesting.
[/quote]

I see that you are using the Neo3pdr yourself (from the gallery link)? So tell me, what does it sound like with and without the back cup? I'm curious to know. Thanks.

gitarretyp · « **Reply #7 on:** 31 Jan 2007, 06:34 am »

I don't have first hand experience without the cup, but zaph noted that it's overdamped without the rear cup and two prominent designers on this forum prefer it with cup. It also has a rising frequency response sans back cup.

johnk... · « **Reply #8 on:** 31 Jan 2007, 01:34 pm »

I looked at it but it's just not a very good tweeter. The response of my samples wasn't very smooth to start with and dropped off like a rock at about 1.5k as I remember.

ebag4 · « **Reply #9 on:** 31 Jan 2007, 03:05 pm »

Here is an OB that uses the Neo3PDR with an open back. They seem to like it.

http://www.adireaudio.com/Home/KITDDR.htm

Danny Richie · « **Reply #10 on:** 31 Jan 2007, 03:26 pm »

Quote

I looked at it but it's just not a very good tweeter.

I got quite the opposite impression, but of course I actually listened to it. I also get a fairly smooth response from it and better off axis response horizontally than with dome tweeters. I have worked with a ton of different dome tweeters and can't think of any that will outperform the Neo 3 pdr. It also is capable of being easily crossed in the 1,500Hz to 1,800Hz range.

opnly bafld · « **Reply #11 on:** 31 Jan 2007, 06:44 pm »

Quote from: Danny on 31 Jan 2007, 03:26 pm

Quote
I looked at it but it's just not a very good tweeter.

I got quite the opposite impression, but of course I actually listened to it. I also get a fairly smooth response from it and better off axis response horizontally than with dome tweeters. I have worked with a ton of different dome tweeters and can't think of any that will outperform the Neo 3 pdr. It also is capable of being easily crossed in the 1,500Hz to 1,800Hz range.

Danny,
What is your opinion of the differences with the back on and off?

Thanks,
Lin

konut · « **Reply #12 on:** 31 Jan 2007, 08:18 pm »

I am surprised at johnk's response as I'd seen the tests at Krutke's site as well concluding the NEO3s were better than most, if not all, planar tweeters available. http://www.zaphaudio.com/nondomes/

Danny, as long as I might have your attention, what would be the the lowest frequency you'd want to cross over the NEO3 using a 1st order cross over?

ctviggen · « **Reply #13 on:** 31 Jan 2007, 08:52 pm »

I think the rear tweeter is a stellar idea for the Orions. It makes me want them again or at least experiment with them.

Danny Richie · « **Reply #14 on:** 31 Jan 2007, 10:07 pm »

Quote

What is your opinion of the differences with the back on and off?

One big difference is how the back cup loads the diaphragm and what that loading does to the response. With it off it starts loosing output higher up in its range and has a nice gradual roll off.

With the back cup it remains flatter longer then takes a steep dive around 1,500Hz.

For me it is easier to work with and easier to get that low frequency crossover point with the back cup on it.

The sound is similar. I will need to re-look at the effects sonically of it as a dipole driver. One thing working against it in that configuration, for me, is that my listening room is very well treated. High frequency output gets absorbed easily into tube traps and wall panels.

Quote

I am surprised at johnk's response as I'd seen the tests at Krutke's site as well concluding the NEO3s were better than most, if not all, planar tweeters available. http://www.zaphaudio.com/nondomes/

It does have really low distortion but I don't really think that you can judge its performance by that only. That isn't why it sounds so good, but it certainly shows that there are no problems in that area.

Quote

Danny, as long as I might have your attention, what would be the the lowest frequency you'd want to cross over the NEO3 using a 1st order cross over?

It depends some on the output level of the woofer you are matching it to. You could use it with an open back and use one cap in line with it if you have a pretty decent value resistor in line with it by-passed with a small value inductor to reshape the response into a more usable slope. Still I couldn't image crossing much lower than 2kHz.

opnly bafld · « **Reply #15 on:** 31 Jan 2007, 11:20 pm »

Thanks Danny.

Lin

konut · « **Reply #16 on:** 31 Jan 2007, 11:24 pm »

Thanks for the quick response. So if, for instance, I'd use a 1st order cross over at 3500hz it wouldn't make much difference in the response if the cup was on or off?

Danny Richie · « **Reply #17 on:** 31 Jan 2007, 11:29 pm »

It will be different. If I get some time in the after this weekend I'll try to shoot some for you.

konut · « **Reply #18 on:** 1 Feb 2007, 02:25 am »

Cool!

wikin · « **Reply #19 on:** 1 Feb 2007, 05:04 am »

Quote from: johnk... on 31 Jan 2007, 01:34 pm

I looked at it but it's just not a very good tweeter. The response of my samples wasn't very smooth to start with and dropped off like a rock at about 1.5k as I remember.

If this statement is for the Neo3Pdr with the back cup opened then it's a consistent finding with Danny's.