Dipole wall placement

[Rocky]

I am building dipole speakers with Supravox 215 GMF 8'' midwoofer, with a TAD horn for the highs and upper mids.. In the design, this led to some complications due to the heavy weight of the TAD 4001 drivers.. With some 13 kg I had to use 3 layers of 12mm MDF layered with epoxy to get a reasonably stiff baffle (keep it from bending under the weight of the TADs), and it appears to be strong enough. However, to get the most stability, it would be best if the TAD driver could lean towards the wall (as shown in the attached picture). The baffle on the picture will get «fins» to both sides made out of plexiglass to get the baffle wider, I guess it will be around 60cm to 70cm wide when assembled. The horn will be mounted on the baffle in the big circle in front of the compression driver, poking some 10cm out in the air.

Now, will the ~20-30cm spacing provided by the TAD driver give sufficient space behind the dipole so that it'll work properly? Or will I have to find another way of supporting the baffles further into the room?

[Rocky]

BTW the newspaper below the baffles in the pic is not a regular sized newspaper.. It's the huge-issh norwegian Aftenposten

[tgorham3]

Originally posted by Rocky
Now, will the ~20-30cm spacing provided by the TAD driver give sufficient space behind the dipole so that it'll work properly? Or will I have to find another way of supporting the baffles further into the room?

If you have access to Microsoft Excel download a copy of XLBaffle and model performance. Unless your bass driver has a lower Qts than I would guess, given the choice of an OB, 20-30 cm is probably going be a bit close. On the up side, wings may be unnecessary.

XLBaffle Download

[Gregm]

I would suggest at least 75cm-1m away from back & side wall (let the Supra breathe a bit).

Maybe a tripod type of support for the Tad would be appropriate?

[Rocky]

Thanks for the XLBaffle link.. With regards to wings on the upside, I'll test all possible wings before making some nice looking ones..

Maybe a tripod type of support for the Tad would be appropriate?

Explain what kind of device this tripod type support is.. Some sort of metal frame?

[phase_accurate]

Since the lower driver is elevated, why don't you use a triangular shaped piece of wood on the backside, in order to make it stand upright. A little less elegant but giving better stability would be using two of these on each side.

Regards

Charles

[Rocky]

Originally posted by phase_accurate
Since the lower driver is elevated, why don't you use a triangular shaped piece of wood on the backside, in order to make it stand upright. A little less elegant but giving better stability would be using two of these on each side.

Regards

Charles

Very nice idea. I would definitly go for a single one at the centre of the backside. I can make a big fat one using layered MDF too

Check out my new active cables being constructed for the dipoles: Besides active filtering, they'll provide two gainclone channels of 5 watts!! All battery powered!!

[mbon]

Originally posted by Rocky
I am building dipole speakers with Supravox 215 GMF 8'' midwoofer, with a TAD horn for the highs and upper mids.. In the design, this led to some complications due to the heavy weight of the TAD 4001 drivers.. With some 13 kg I had to use 3 layers of 12mm MDF layered with epoxy to get a reasonably stiff baffle (keep it from bending under the weight of the TADs), and it appears to be strong enough. However, to get the most stability, it would be best if the TAD driver could lean towards the wall (as shown in the attached picture). The baffle on the picture will get «fins» to both sides made out of plexiglass to get the baffle wider, I guess it will be around 60cm to 70cm wide when assembled. The horn will be mounted on the baffle in the big circle in front of the compression driver, poking some 10cm out in the air.

Now, will the ~20-30cm spacing provided by the TAD driver give sufficient space behind the dipole so that it'll work properly? Or will I have to find another way of supporting the baffles further into the room?

Supravox told me that open baffled needs something like two meters away from back wall to have maximum expression.
I'm very interresting by the 215 RTF, how the 215GMF sounds ? Do you enjoy it ? you can use it from 150 Hz to 5000 Hz in open baffled.

[Rocky]

Originally posted by mbon

Supravox told me that open baffled needs something like two meters away from back wall to have maximum expression.
I'm very interresting by the 215 RTF, how the 215GMF sounds ? Do you enjoy it ? you can use it from 150 Hz to 5000 Hz in open baffled.

Dunno how they sound yet, as they have not yet arrived. Didn't even have a chance to audition any supravox stuff before ordering, so this is kind of casino.. Most reports i've heard gives positive feedback exept some comments about varying build quality.. Specs are great though..

From 150 cycles??? Maybe if mr.Linkwitz designed my baffles Planning on gettting mine down to some 50-60 cycles... Two meters also sounds like an awful lot of space... unneccesarily much space.. Can't really understand why they would say such a thing..

[tgorham3]

Originally posted by Rocky


Can't really understand why they would say such a thing..

Think of the front wave as + and the backwave as -. Theorectically, when you add the two, you have 0.

Closer you are to the back wall the quicker (the higher the frequency) that you will get to 0.