M-Tw-MB-W-W

Mzisserson

Hi guys,
   I have alluded to my "Magnum Opus" build and am still working on layout detail. Luckily, I will be able to order the remaining drivers after the holidays due to some undeserved good fortune.  

Roman has done a lot of work on drawing up the cab so far which is about a 50" tall trapizoid. 2 Seas l26 10" woofers in 4CF of space will anchor, to a Morel TI sureme midbass, to a 2" morel elite dome mid (basically a jacked-up 55) and a scan illuminator 3/4" dome will top it off. 

My only hang-up right now is layout. Sometimes simpicity is best. I like a center-lined t-m-mb-w-w for this config, but it will put the tweeter pretty high on a baffle with a 2-degree tilt. About 5"-7"higher than I like tweeters which is usually 35"-39" from the floor (Using a large, shallow angle facet on the top)

If I switch to a m-t-Mb-w-w layout, it will help push the tweeter down to a more reasonable height, but increase diffraction artifacts as  the baffle width increases and now I have to be very cautious of the crossover between the MB and the M. 

I think I understand the pluses and minuses of both, but was wondering any thoughts you guys may have. 

Since Roman is CNC-ing these, I will likely in-lay some 1/2-3/4" Felt in the aera of the tweeter and mid to help with diffraction. 

squamishdroc

Unfortunately I don't have enough knowledge to contribute but it sounds like a great build!  

Mzisserson

squamishdroc said:

Unfortunately I don't have enough knowledge to contribute but it sounds like a great build!  

Thanks. I have reached the poinr where I think I am ready to attemt a "last pair" type build. Ill still buid to tinker and for others, but I want my final pair....

jr@mac

I vote for vertically aligned small to big. Or maybe a dual opposed alignment with the large drivers, one front and one rear firing. 

Sounds like a killer build.

Mzisserson

jr@mac said:

I vote for vertically aligned small to big. Or maybe a dual opposed alignment with the large drivers, one front and one rear firing. 

Sounds like a killer build.

Thanks man, I hope it is killer... Roman is extremely generous to the DIY community and is dealing with my ever-changing demands despite us not being married. He has the hard job, not me.  

I tinkered with the idea of dual opposed since there are real distortion bennies, but it does not reduce the box requirement and since they will run ALL the way up to about 200Hz, I don't want any weird cardioid things going on. The lambda is about 5 feet at 200, which would still mutually couple the woofers, but during roll-off if I end up 2nd order-ish as planned, I do not want to end up with issues with them still squeaking noise out at 400 which has a lambda of about 2.5 feet.  

Guess I could push it to a 4.5 way... What the heck at this point! The gravity of a TMMbWW alignment is strong, I was hoping to get a compelling reason to change it, but so far, nada. 

D1PP1N

Any design pics of the cabinets? Roman is doing some awesome work from the last few threads of his i checked out. 

PSchumacher

The wider baffle won't increase diffraction artifacts.  It just changes their locations.

Mzisserson

PSchumacher said:

The wider baffle won't increase diffraction artifacts.  It just changes their locations.

Locations as in frequency.... Yes. 

I think my gripe is the whole: "What do you want your waveguide to look like?"Thing. A wide, flat baffle with a tweeter on it is not my ideal waveguide. I have found a preference for a thin baffle around the tweeter to make it as close to a floating point as possible.

PSchumacher

Model it up.  The diffraction effects become less bothersome for a tweeter the wider the baffle gets, especially as you move up in the crossover frequency.