[Bumpy]

What tweeter orientation is recommended to cover the higher frequencies of 3 way open baffles?

1) A dipole tweeter located adjacent to the midrange driver within the baffle.

2) A forward firing monopole on top of the baffle.

3) An upward firing monopole on top of the baffle.

4)  A combination of two monopoles on top of the baffle, one firing forward and the other rearward.

5) An omni-directional driver on top of the baffle.

Does anyone have an opinion on this?

I am not asking for recommended manufacturers.

[matevana]

Where three-way designs are concerned, I've always been intrigued by the Wharfdale SFB. It uses a rear mounted, up-firing monopole tweeter.  It happens to be a very seamless integration.

[Bumpy]

Where three-way designs are concerned, I've always been intrigued by the Wharfdale SFB. It uses a rear mounted, up-firing monopole tweeter.  It happens to be a very seamless integration.

Yes, I've noted that too, and the SFB is a speaker with a cult status.  I could be wrong but I think that tweeter is a paper cone dipole

[Tyson]

AMT with open back or Neo3 with open back both are great OB tweeters.

[matevana]

Yes, I've noted that too, and the SFB is a speaker with a cult status.  I could be wrong but I think that tweeter is a paper cone dipole


Yes, you're right. It's not in a chamber so it's technically an up-firing dipole. I'd be tempted to try something like a Fostex FF85wk.   

[Bumpy]

Thanks for the recommendations, but for the moment I would like to concentrate solely on the location and tweeter type (monopole, dipole, omni directional etc)

Thanks

[Bumpy]

Interesting comments from Linkwitz Labs. They pretty much eschew the idea of rear facing tweeters or indeed dipole tweeters


Q25 - Why do you not use a rear firing tweeter or a dipole ribbon tweeter?

A25 - A rear firing tweeter for the PHOENIX would increase the speaker's high frequency 4p acoustic output by 3 dB for an even more uniform power response. In earlier designs I actually used such a tweeter. Because of the physical size and separation of the two tweeters - in terms of wavelength - it is impossible to obtain a simple cos(a) polar response. Instead, the off-axis response will consist of multiple beams, where the outputs of the two drivers see each other, which is primarily off-axis. On-axis, in front, the rear tweeter contributes very little to the sound. Overall I have not found a real benefit resulting from a rear tweeter. The off-axis response of the single tweeter-midrange combination is well behaved and actually has its widest dispersion around 4 kHz. Above that point the normal increase in tweeter directivity comes into play. Also, a rear tweeter may cause reflections from nearby objects which affects imaging and makes speaker placement critical. I am therefore using only a front tweeter.

A dipole ribbon tweeter would have the same potential problems as a rear tweeter. In addition the low 1440 Hz crossover requires large volume displacement capability. Typical high frequency ribbons would generate severe non-linear distortion under this condition.  A ribbon of greater length would narrow the vertical polar response too much. The large amount of air movement due to the close proximity of the 8" drivers might modulate the movement of the low mass ribbon and lead to further distortion. I have not used a ribbon driver, because the ones that I am aware of do not seem to fit this application.

[WC]

Linkwitz must have changed his mind. The LX521 have front and rear facing tweeters. 
The LX-mini has a full range driver acting as a dipole with some of the backwave damped.

[Bumpy]

Its nice to see what they say backed up by measurement as well as listening.

[ossidian]

If one is using a large midrange driver I prefer the AMT, one gets 40khz down to 900hz (depending on model used).
The AMT 500 is rather large with a cultured marble baffle where as the AMT 700 and 900 models have a more scaled down baffle.
Hawthorne did make several AMT drivers that were fantastic. The AMT 500 is what I am currently listening to in my system.
Yes Hawthorne is currently out of business (Canadian company is taking them over soon) but the drivers can be found.

[Bumpy]

It's not in a chamber so it's technically an up-firing dipole. I'd be tempted to try something like a Fostex FF85wk.

Apparently the best placement is alignment of driver acoustic centres CTC. The optimum is dual concentric, but the SFB tweeter position gets next closest, so might be worth exploring.

[OzarkTom]

Plasma tweeters are the best I have ever heard, no mass. There is a new tweeter you might look at if you have the patience to wait for it, coming out soon. The Air Blade Tweeter.

https://www.arya-audio.com/airblade

[Bumpy]

Plasma tweeters are the best I have ever heard, no mass. There is a new tweeter you might look at if you have the patience to wait for it, coming out soon. The Air Blade Tweeter.

https://www.arya-audio.com/airblade

Looks very interesting, but no mention of sensitivity or price.

[OzarkTom]

Not sure about the sensitivity or price. More info here.

https://www.reddit.com/r/diysound/comments/8srhhh/im_arthur_marker_audio_researcher_and_founder_of/

And here.

http://www.christensenaudioip.com/

Facebook page

https://www.arya-audio.com/?fbclid=IwAR1nAgVk6F77xYAdNE-4zm3Jban75mRnFBb1Z7ONZL1REhLr9-UMOdwX9ps

[OzarkTom]

I have found out a little more on the Air Blades. Tentative price is $1300 a pair and sensitivity is around the lower 90's. But that is not concrete.

[Bumpy]

I have found out a little more on the Air Blades. Tentative price is $1300 a pair and sensitivity is around the lower 90's. But that is not concrete.

Thanks, was looking for about 95 sensitivity, but will keep an eye out for it.