budget open baffle bass for planars

Beardy · « **on:** 14 Dec 2012, 08:23 pm »

I have a set of MMGs and in the long term a pair of servo drivers and appropriate amps are probably in my future. However, I am interested in trying a lower cost approach right now as I dont want to drop a k on this...

Given that the MMGs are pretty inefficient, I wont need huge amounts of amp for conventional cone drivers. So I am planning on 2x Dayton APA150 bridged to give 150W into 4Ohms. I could go with a plate amp or perhaps even an conventional amp and active crossover. I am intending to use 2x 61/2 or 8 inch drivers per side in H frames. I am hoping that by using an OB and lower mass drivers I might be able to avoid some of the `bloat'/'looseness' of a boxed large driver.
I am expecting that it could be done for $400 per side...?
I am looking for advice and guidance on the best way of doing this, appropriate drivers etc....
thanks
mike

studiotech · « **Reply #1 on:** 14 Dec 2012, 09:20 pm »

Generally speaking, 2 6.5" or 8" drivers are not going to get you much better bass than what the MMGs can do all on their own. You need to be thinking more like 2 10" minimum. Try the search function on this forum or the planar forum for lots of ideas and opinions.

Greg

JohnR · « **Reply #2 on:** 15 Dec 2012, 01:39 am »

Agree with Greg... paradoxically, large drivers are actually more budget oriented than small ones. A pair of 15's each in a shallow H-frame would probably be your best bet. Lots of examples in this forum. Also... rather than those amps, something like a QSC GX3 would be a much better amp - the catch there being that you would need to position it where the fan noise wasn't an issue.

Small drivers (reportedly) can work in OB but it's not as simple... here's an example:

http://www.enjoythemusic.com/diy/0911/slot_loaded_open_baffle_speaker.htm

Beardy · « **Reply #3 on:** 15 Dec 2012, 04:02 am »

OK, noted.

can you recommend a low mass/big motor sub driver?
thx

studiotech · « **Reply #4 on:** 15 Dec 2012, 04:30 am »

Quote from: Beardy on 15 Dec 2012, 04:02 am

OK, noted.

can you recommend a low mass/big motor sub driver?
thx

Well, the big motor MAY be a disadvantage for OB woofers. Big motor usually means lots of strength and control over the cone and this usually means a low QTS. What many recommend for easy OB solutions is high QTS. Basically it gets you a boost near the FS of the driver. Basically free EQ if you will. Personally, and this is just me, I would look for a nice woofer around .5-.7Qts and EQ to taste from there. Back when I was running my Maggies, I used a pair of MB Quart 12" subs per side. These were around .5 Qts, but are no longer made, so I will not give a link to something unobtanium.

Many folks like the Eminence Alpha 15 which has an even higher Qts. There are lots of projects listed on here with those drivers. There are others who feel that the Qts of these is too high and can affect the precision of the bass they reproduce. I am in this camp of belief. There WILL be loads of bass, but is it precise? From the fact that you are asking for light cone and large motor, I assume you are imagining nice tight, clean bass. Not sure you will be happy with the Alphas. What kind of SPL do you tend to listen at?

One of these per side might be nice:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-468

They are known to have a pretty quite motor and a reasonable Qts and a nice low Fs. You could try one per side to start with.

This is also a nice choice:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-1118

Greg

studiotech · « **Reply #5 on:** 15 Dec 2012, 04:37 am »

I heard these in a system last weekend and they dug really deep with authority and sounded nice and clean doing it. One per side was fine with a nice H or Z frame. Z frame saves space and looks more like a single 12" boxed sub if you add grill cloth.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=294-301

Or the one with higher Qts:

http://www.parts-express.com/pe/showdetl.cfm?partnumber=294-3108

I second the idea of a pro amp too. Maybe something like the Peavey or Behringer with built-in DSP to make connections that much easier. But plan on swapping to quieter fans or locating in a closet or adjacent room.

Greg

Beardy · « **Reply #6 on:** 15 Dec 2012, 06:14 pm »

thinking of a couple of these per side
http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-1110

remembering that the Maggis dont play super loud anyway...
2 in an H frame about 14 inches deep, one pointing back and one forwards.

sound reasonable?
(forgive the pun)

studiotech · « **Reply #7 on:** 16 Dec 2012, 02:59 am »

Looks like a decent budget choice.

You know, I've still got my old Outlaw ICBM around if you'd like to be able to keep the Maggies signal path analog. If you're interested, I'd sell it to you.

http://www.outlawaudio.com/products/icbm.html

Greg