[Bumpy]

Just checking, but should these be wired in or out of phase?

[Bumpy]

Just checking, but should these be wired in or out of phase?

We're not very knowledgeable are we. One hundred views and no answer

[T4Man]

Because you're mimicking a dipole unit, it would be wired out of phase.

[Bumpy]

Because you're mimicking a dipole unit, it would be wired out of phase.

Thank you. I am guessing if I tilt it upwards to give more ambiance then it’s trial and error after that.

[DannyBadorine]

It's more complicated than just wiring them out of phase.  That's a start but depending on how and where they are mounted you could be running into all sorts of off axis problems.  Why not just use a dipole tweeter?

[T4Man]

I guess my thinking would be mounting them parallel to each other would give the greatest time difference. That could avoid the combing problem.

[T4Man]

It's more complicated than just wiring them out of phase.  That's a start but depending on how and where they are mounted you could be running into all sorts of off axis problems.  Why not just use a dipole tweeter?

Doesn't that eliminate soft dome tweeters? Then I'd wonder about the vertical off axis response, or if that's important.

[T4Man]

  I  meant vertical.

Fixed it.

[Openly Baffled]

Just checking, but should these be wired in or out of phase?

Ok. I'll dive in with an "answer".

As the cones (or domes, rings etc.) of back-to-back tweeters are more than half a wavelength apart depending of frequency, there is probably no correct answer to this question.

If they are wired in phase then theoretically you will get a null 90 degrees off axis but this may not give the best sound.

I guess I'm saying try it and see.
I did some experimentation and got different measureable results by varing the phase and distance, but my listening tests were inconclusive with a pair of Vifa's ring tweeters.

Hope this helps.
 

[Bumpy]

I guess I'm saying try it and see.
I did some experimentation and got different measureable results by varing the phase and distance, but my listening tests were inconclusive with a pair of Vifa's ring tweeters.

Hope this helps.

As a slight aside, with big open baffles and room interactions where do you make measurements?

I have always felt that a position midway between where my ears would be is best.

[Openly Baffled]

As a slight aside, with big open baffles and room interactions where do you make measurements?

I have always felt that a position midway between where my ears would be is best.

Listening tests inside but directivity/FR tests outside on a rig largely free of reflections in the mid-treble range. I rotate the speaker and keep the mic on the ladder... look closely!!

[Bumpy]

Interesting

So are you saying that you do all measurements in free space and only do listening tests (not measurements) from the seating position?

[Openly Baffled]

Interesting

So are you saying that you do all measurements in free space and only do listening tests (not measurements) from the seating position?

I do a full range of tests in my listening room but apart from distortion measurement they need to be near field to get results that aren't effected by the room. I've tried windowed impulse response for FR but when I'm tuning crossovers I prefer a continuous measurement.

Outdoor measurements are good for seeing the behaviour of a specific driver in a specific baffle geometry.

IMO I think outdoor measurements are useless unless it sounds good in your room, but outdoor tuning should ensure it sounds good in most rooms.

[DannyBadorine]

Doesn't that eliminate soft dome tweeters? Then I'd wonder about the vertical off axis response, or if that's important.

The problem is the interaction between drivers depending on where they are placed.  I don't quite understand your question about soft domes.  I understand that they disperse all directions but my concern with using more than one tweeter is the interaction between the two, which is different than one tweeter interacting with the box it's placed in.

[DannyBadorine]

Ok. I'll dive in with an "answer".

As the cones (or domes, rings etc.) of back-to-back tweeters are more than half a wavelength apart depending of frequency, there is probably no correct answer to this question.

If they are wired in phase then theoretically you will get a null 90 degrees off axis but this may not give the best sound.

I guess I'm saying try it and see.
I did some experimentation and got different measureable results by varing the phase and distance, but my listening tests were inconclusive with a pair of Vifa's ring tweeters.

Hope this helps.

This is well said and it illustrates the potential problems I'm bringing up.

[DannyBadorine]

Listening tests inside but directivity/FR tests outside on a rig largely free of reflections in the mid-treble range. I rotate the speaker and keep the mic on the ladder... look closely!!

I just got one of these rotating platforms and it is much easier to do off axis measurements now.
https://www.arborsci.com/products/rotating-platform

[Openly Baffled]

I just got one of these rotating platforms and it is much easier to do off axis measurements now.
https://www.arborsci.com/products/rotating-platform

Thanks Danny,
I can already see it marked with specific angles.
That could to a tool for my next build, hopefully in 2024.

[Poultrygeist]

It works for me.

[Bumpy]

Has anyone gone down the route of back to back tweeters as practiced in the very well regarded Linkwitz LX 521 open baffles. The drivers he uses are not prohibitively expensive, but of course you need two per side.

https://www.falconacoustics.co.uk/drive-units-1/seas-drive-units/seas-linkwitz-lx521-orion-driver-sets/seas-27tffncg-h1396-04-tweeter-prestige-series.html

[Bumpy]

So has anyone even seen or heard the Linkwitz LX521?