Winter's OB project - feedback requested

[Zodiac]

Objectives:
110dB SPL continuously capable
All drivers minimally baffled
Utilize dipole tweeter
Utilize monopole subs for difficult last few octaves

Drivers:
Bass - AE Dipole 15, 70Hz-200Hz
Mid - 2 x Seas W15, 200Hz-1800Hz
Tweet - Mundorf AMT2310 1800Hz+

Mid/Tweeters arranged in correctly spaced MTM arrangement. High slope linear phase XO between mid and tweeter. Monopole JL Audio F112 subs used below 70Hz, 24db/oct LR XO.

Other equipment:
DEQX HDP-3
Bel Canto EVO200.6 (6 channel amp)

Construction:
3" MDF sandwich for the back brace, 1" ply for the bass panel, 3/4" for the MTM panel. 1" thick granite stone for base weight.

Any feedback on driver choice, XO points, construction, anything else?

This is my first full from scratch design, although I did put together and currently own the Linkwitz Orion. I have read as much as I can of the Linkwitz site and also John K's site, incl. reviewing his dipole design guide.

[homebuilder]

I like your design a lot. Especially the bass section. Love the back brace too. Could I suggest that you might want to curve that backside of the brace up to meet at the top of the upper panel? I think that being supported only at the bottom, no matter how thick the back brace below....it is going to wobble like crazy.

I have not listened to the driver selection, so cannot comment on that part of it. Good luck to you!

[CLS]

Beautiful

In such design, for "defending" the vibration, I think soft is better than stiff. It's nearly impossible to make a real mechanical grounding to make the whole speaker vibration free. On the contrary, soft mounting can lessen or totally eliminate the vibrations. The softest is by suspending the drivers by strings.

Keyword: "swing"

[6.283]

looks cool !

Originally Posted by Zodiac

Tweet - Mundorf AMT2310 1800Hz+

The 2510c has better off axis behavior but is larger. On the other hand you can remove the face plate.

Originally Posted by Zodiac

High slope linear phase XO between mid and tweeter.

Using the DEQX or anything else ?

[DQ828]

I like the design, certinally looks much easier than the one I can up with. The information supplied by others in my thread suggested that the Dipole 15 would get down into the low 30's and save all of the extra work with the sub. I guess if you want to go below that then the subs a must. Oh my 15 is going in a H frame which makes a difference.

Sorry I cant be of much help as I still have my "L" plates on. good luck I will follow with interest.

[StigErik]

Nice design, I like it. Mid and tweeter selection is right up my alley...

A few thoughts though...
1. To get the best (horizontal) off-axis response, the tweeter should be as narrow as possible. The best is using the driver "nude" - no baffle or frontplate.
2. Why not extend that "arm" holding the mid/tweeter baffle all the way up, and suspend (hang) the mids and tweeter from there? Much better decoupling of vibrations.
3. 200 Hz is too low XO point for the mids, I would go up to 300-350 Hz.

[DQ828]

I dont know if this link will be of any use I stumbled on it when searching the Seas driver Midrange test data

[el`Ol]

Are you sure that the DEQX does the extreme boosting? I would ask the manufacturer first.

[Zodiac]

Thanks everyone for the feedback!

Originally Posted by 6.283

The 2510c has better off axis behavior but is larger. On the other hand you can remove the face plate.

Using the DEQX or anything else ?

The 2501 would be too big (too great driver separation for the MTM design and XO point)

Will be using the DEQX for linear phase XO

Originally Posted by DQ828

I like the design, certinally looks much easier than the one I can up with. The information supplied by others in my thread suggested that the Dipole 15 would get down into the low 30's and save all of the extra work with the sub. I guess if you want to go below that then the subs a must. Oh my 15 is going in a H frame which makes a difference.

My modeling shows the Dipole 15 is displacement limited on that baffle size at a 70Hz crossover point whilst meeting the 110dB SPL requirement. I will get quite a bit more SPL than the model shows though due to the 2pi radiation (+6dB). I wanted to keep a bit of flexibility with XO point experimentation. Running down to 30 would require a H frame or multiple drivers. In any event I am a strong convert to leaving low bass reproduction to a monopole subwoofer in the interests of space!

Originally Posted by StigErik

A few thoughts though...
1. To get the best (horizontal) off-axis response, the tweeter should be as narrow as possible. The best is using the driver "nude" - no baffle or frontplate.
2. Why not extend that "arm" holding the mid/tweeter baffle all the way up, and suspend (hang) the mids and tweeter from there? Much better decoupling of vibrations.
3. 200 Hz is too low XO point for the mids, I would go up to 300-350 Hz.

1) I have seen your nude speakers, what kept me from doing that rather than the minimal bafffle was the added complexity of driver mounting...
2) That is a possibility. How do you hang drivers?
3) My excel modeling using John Ks tool shows I can get 118dB SPL using a LR4 200Hz XO since the W15s have very good XMAX (6mm). Is there some reason why I couldn't? I looked at using a single W15 but although XMAX was good power handling would have been an issue.

[6.283]

Originally Posted by Zodiac

since the W15s have very good XMAX (6mm).

I see +-4 linear xmax