[Bumpy]

As those of you who have followed my posts will know I have been using circular interchangeable baffles to mount and evaluate a number of 8 inch midrange drivers in an existing main baffle.

I am now settled on the mid ranger and my attention moves to the dipole tweeter.

Unfortunately the additional circular baffle has the negative effect of pushing the tweeter further back into a recess, giving opportunity for reflections as the forward sound emerges. Its not unlike a crude horn loading. So I would like to debate the options.

There seems, to me, to be 3 main options

1. Apply foam around the tweeter opening to reduce reflections
2. Mount the tweeter further forward so it fits flush with the baffle
3. Mount the tweeter (without significant baffle) alongside or above the main baffle so it is essentially in free air.

The tweeter will run from about 3Khz upwards

What are your thoughts?

[Tyson]

You want the tweeter as close to the midrange driver as possible or you will end up with very bad vertical lobing effects.  If it were me, I'd drill out space next to the midrange driver and put a tweeter there.

[Bumpy]

You want the tweeter as close to the midrange driver as possible or you will end up with very bad vertical lobing effects.  If it were me, I'd drill out space next to the midrange driver and put a tweeter there.

Thanks Tyson. So for clarity would it need to go even closer to the mid ranger than it is now, and presumably mounted towards the front of the baffle.

Incidentally, how would bad vertical lobing show itself in the sound quality?

[Tyson]

Oh, so the tweeter is the little beige driver?  I thought that was the midrange.  OK, then it's fine where it is.  I thought you were going to do something crazy like add another tweeter to the top of the speaker or something like that. 

I am actually a fan of aligning the tweeter magnet with the midrange magnet as much as possible and then using the baffle as a bit of a wave guide for the tweeter.  This gets you better time alignment and also better matching of directivity between the tweeter and the mid.  And it looks like that's already what you have, so I wouldn't really change anything with regard to placement of the tweeter.

[Bumpy]

Oh, so the tweeter is the little beige driver?  I thought that was the midrange.  OK, then it's fine where it is.  I thought you were going to do something crazy like add another tweeter to the top of the speaker or something like that. 

I am actually a fan of aligning the tweeter magnet with the midrange magnet as much as possible and then using the baffle as a bit of a wave guide for the tweeter.  This gets you better time alignment and also better matching of directivity between the tweeter and the mid.  And it looks like that's already what you have, so I wouldn't really change anything with regard to placement of the tweeter.

Yes its the little beige driver. Its a vintage alnico, paper cone Saba, suited to dipole as it is open at the back. It also is voiced close to the vintage mid and bass. it is indeed voice coil aligned with the mid ranger.

I will try and find some way to smooth out the front opening to the tweeter. Perhaps I can find a waveguide, that I can cut down to make fit. What do you think.

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