SB 8 inch woofer sounds great on its own. - diyAudio
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Old 18th January 2013, 07:05 PM   #1
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Default SB 8 inch woofer sounds great on its own.

I am listening to new SB 23NRX45-8 woofers in flimsy cardboard boxes sitting on top of my 12p Pensils and I am puzzled. They sound great! I bought them as woofers after reading about a posters use of them on OB with the 12p so I cut some holes in cardboard boxes and hooked them up to my 300b mono blocks to break them in. Maybe my hearing is shot but they sound rich and full and only just missing treble as I listen to a cello concerto. Anyways, I wondering if anyone has any experience using these as full rangers with a super tweeter or such. I know that makes them 2 way so this can be moved to the multiway forum.

Jp
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Old 18th January 2013, 07:17 PM   #2
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I'm not to surprised, but your plan to add a super tweeter is a bad idea. Stick to your initial plan.

Lets take a look: http://www.solen.ca/pdf/sb/sb23nrxs458.pdf

Beautiful until 1khz. Still not bad until 2khz. Then it starts to have some fairly aggresive break up. Listening full range might sound decent right now, and anything "wrong" in the high frequencies might sound like they can be fixed with a tweeter, but not so. We can see that driver makes sound all the way to 8khz! So it sounds like all it needs is some upper end fill in. But it won't be good sound. Especially when you start to turn things up. That break up will start to really scream at you.

Very nice woofer though. I'd try and keep everything from 1khz and up, at least 24db down from the rest of the speaker output. 48db would be much better. Maybe 30db down at 1khz and 42db down at 2khz using a 12db/oct filter. That would put the fc around 250hz. That's -6db at 250hz. You'd likely have to reverse the polarity of the alp12p.
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Old 18th January 2013, 07:43 PM   #3
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I have a pair of Alpair 7.3 gathering dust. I wonder if there is any way to use them in a 2 way design with the SB woofers? Unfortunately I know very little about designing crossovers and cabinets ....

Jp
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Old 18th January 2013, 07:54 PM   #4
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For that kind of ap the A7.3 in an ~5 litre sealed box works well. Box for the SB i'm not sure, haven't yet looked at it yet.

Easiest to biamp, a PPLXO 1st order somewhere between 160-250 Hz would do the trick.

Passive XO would be more difficult, but given the frequency range a simple series XO could work out well. Pulling some numbers from the air one could start with 5mH + 50 uF.

dave
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Old 18th January 2013, 08:04 PM   #5
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I'd use the smaller full ranger (alp 7.3). Mating them wouldn't be a problem at all. Still shoot for the 250hz range. Or lower like Dave suggests is going for a 6db/oct slope.

If you don't know much about cross overs, and not using someone else's design, can I suggest the minidsp. Cheap to buy, works very well, easy to use, can experiment with many options. In this case, you could try 1st order all the way to 8th order and at various frequencies too. You'll need extra amps though. Or PPLXO like Dave suggested, which is a little less intuitive, but even cheaper.
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Old 18th January 2013, 08:09 PM   #6
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Looks like I have a lot of learning to do, but I am still amazed at how these brand new woofers sound in a cardboard box from the Costco. I will ask over on the multiway forum for suggestions on a box for the SB pair.

Jp
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Old 18th January 2013, 08:43 PM   #7
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The SB stuff is pretty amazing. It'll only get better

If you want help with the cross over and stuff, let me know. I've recently done an 8" plus 3" two way like this using a silver flute woofer and a little tang band full ranger. You're going to really like the results
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Old 18th January 2013, 09:36 PM   #8
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That sounds great! I have used an online crossover calculator before but I suspect it is far from optimal. I would like to try a two way with the MA 7.3 and the SB woofers but really don't know how to pick a crossover point to start. I assume somewhere between 1000Hz and 2000hz.

John
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Old 18th January 2013, 09:45 PM   #9
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Quote:
Originally Posted by sootboots View Post
I assume somewhere between 1000Hz and 2000hz.
That would be a waste. Somewhere between 150 and 350 Hz

dave
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Old 18th January 2013, 09:47 PM   #10
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by sootboots View Post
Looks like I have a lot of learning to do, but I am still amazed at how these brand new woofers sound in a cardboard box from the Costco. I will ask over on the multiway forum for suggestions on a box for the SB pair.

Jp
If you think cardboard sounds good, try foam core enclosures.
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