12" EV fullrange in open back cabinets

[Fuling]

Hi!

A while ago someone gave me a pair of EV SP12B full/widerange drivers.
I kept them in storage for almost a year before I dug them up and put them in a pair of (small) open baffles a few weeks ago. I cross over to a pair of DIY multicell horns at ~900Hz.
OB works fairly well in my assymmetric livingroom but even with a passive EQ network and a low DF amp the bass is a bit light.
Larger baffles is not really an option and there´s no room for properly placed dipole subs so I´m looking for some kind of folded baffle solution.
I believe adding wings at 90 degrees back from the baffles might cause resonance problems, but what if I fill the cavity with some damping material?
Might even add perforated backpieces to keep the stuffing in place (four cats in the house...).
I understand that the dipole pattern would be compromised, though I´m not sure that would be a bad thing. Depending on the hole pattern of the backpieces this may approach aperiodic tuning rather than OB.

I guess the only way to find out if this works for me, in my room, is to try it but I´m curious to hear what other people might have to say about the concept.
I´m a sworn enemy to boomy bass

[bknop]

I've experimented with covering the back of an open baffle with blankets, carpet or other acoustic dampening materials. The results I found were the radiation pattern changes more into a hypercardiod response. The rear wave will be attenuated, but, the pattern will become closer to the original figure 8 the farther the frequency goes down. Also, baffle wings are a good idea especially for smaller spaces, but it is best to have them spread out some to minimize cavity resonance.

hope this helps

[H3nry]

My memory of the SP12B is that it is a little light on bass compared to an SP12. It is designed to work in a large bass reflex box usually tuned to 45-50 Hz. I wouldn't expect it to work very well OB. However, that was a LONG time ago...

[Fuling]

Thanks!

I´m working on a pair of folded prototype baffles right now, will report the results within a couple of days

[rcavictim]

I have a pair of the EV SP-12's. They are similar but have a much larger alnico magnet structure that the SP-12B, a whizzer cone and very high sensitivity. I tried them in a number of different cabinets and was not happy with either the weak bass or the cabinet coloration. I then tried them in a pair of Altec 816A front horn loaded reflex cabinets designed for 15" drivers. I used the aluminum adapter ring that holds a 12" Bozak B-199 woofer in a 15" driver cutout with the two tweeters hung out front to mount the 12" EV's in the Altec cabinet. The SP-12's are run full range and the top end is helped with a small 3x9" HF horn and compression driver with 1st order cap filter and series resistor. My tweeter horns come in around 7+ KHz. How do these peform? In a word WOW! These are the most SET friendly speakers I own. They can fill a large room with a couple of watts. The bass is not deep but it is accurate and adequate given the sensitivity achieved. I am not bothered by any cabinet sound. This combo gets my Two Thumbs Up! BTW, if you want deep powerful bass these drivers are the wrong choice.

I recommend that you try these cabinets for your SP12B's.

http://www.altecpro.com/pdfs/vintage...%20Cabinet.pdf

[Fuling]

Hi

I´d love to build a pair of 816s if there was room for them in my livingroom...
Instead I made myself a pair of folded plywood baffles about 24" high, 16" wide and 13" deep. As expected I got more bass out of the drivers but the mid sounds a bit...constipated

[Badwater]

I use the SP12b on a shallow U frame crossed over to Alpha 15A in a H frame. The EV is rolled off around 200 hz. The Alpha is powered using a small plate amp. I used a Fostex T90A supertweeter on top to supplement the high end. I used Martin King's worksheets to develop the design. Very satisfied with the results.

Bill

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