12" EV fullrange in open back cabinets - diyAudio
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Old 4th October 2009, 12:40 PM   #1
Fuling is offline Fuling  Sweden
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Default 12" EV fullrange in open back cabinets

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 theres no room for properly placed dipole subs so Im 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 Im 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 Im curious to hear what other people might have to say about the concept.
Im a sworn enemy to boomy bass
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Old 6th October 2009, 03:52 AM   #2
bknop is offline bknop  United States
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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
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Old 6th October 2009, 05:46 AM   #3
H3nry is offline H3nry  United States
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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...
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Old 6th October 2009, 03:10 PM   #4
Fuling is offline Fuling  Sweden
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Thanks!

Im working on a pair of folded prototype baffles right now, will report the results within a couple of days
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Old 6th October 2009, 03:34 PM   #5
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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
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Old 8th October 2009, 02:16 PM   #6
Fuling is offline Fuling  Sweden
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Hi

Id 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
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Old 16th October 2009, 11:53 PM   #7
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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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Old 18th September 2013, 03:00 PM   #8
DaveM is offline DaveM  United States
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I know this is an old thread, but I just picked up a pair of SP12's in the vintage 1962 EV box that was sold as a kit. I haven't played with them at all yet, but was wondering if anybody had the Altec design mentioned above.
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Old 18th September 2013, 03:52 PM   #9
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[QUOTE=rcavictim;1943253]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. I do not use the Bozak tweeters, just the adapter ring. 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 perform? In a word WOW! These are amongst the most low power 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 coloration with this setup. 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.
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Old 18th September 2013, 05:03 PM   #10
DaveM is offline DaveM  United States
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That is what I was after. The link above is dead. Which cabinet design do you suggest?
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