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Questions about Box sizing !

Stephen J

Stephen J

Suum Cuique
Ok, I need the famous AK expertise :yes:
I'm trying to bring my EV project together and I have some questions.
I have a box approx. 8.67 gicf and an SP15...seems like a good match.
If I were to add another SP15 as a Helper. Would I have to increase the box size ?
How much?
These are 16ohm drivers,with one wired as a helper will it become an 8ohm load ?
Thanks for any info you may provide....
 
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Wired in parallel, you'd need ~2x the box size. In series, the reduced damping would require a larger box for the same results.

With one wired as a helper, it will act as an 8 ohm driver to the point where it ceases to be a helper and then the speaker acts like a 16 ohm load.
 
Box size and tuning is operative at the low frequencies only, so it's two woofers operating in this region, and tuned accordingly. That likely means a box twice the size as would be suitable for a single.

Yes, when both are operating, the impedance is 8 Ohms, but that only matters to the amp if you're using the "0.5" scheme. It's part of how this works: the amp is delivering more power to the two drivers than it would to just one.

Up at the lowpass frequency, the filter is seeing one driver, 16 Ohms, and calc'd accordingly.... :yes:
 
Ok..

..can you gentlemen help me with a few details of my EV project?
Zilch,I didn't want to post this in the eWave thread because its not a two way project.
Mr.Newwwwman ...I have read a lot of your posts and have both learned and been inspired. 'sides you live in MI. :D
I have some EV Sentry IV crossovers....they went with an 8ohm system.
My tweets are 8ohm,as are my mid drivers. However my SP15's are 16ohm.
Pitching the 2 per box idea. Is there a way to make this work ?
i.e modding or upgrading the XO's ?
This stuff sound pretty damn good as is,but given the ohm discrepancy I feel like I could be doing better still.
Thanks,
 
When I get a chance to review the crossover, I will. If you have a telex link to the schematic and want to post it, I wouldn't mind. Just curious if they were using any trickery in the crossover of if it's a simple text book low pass crossover. If the latter, you may have a fair shot at getting suitable performance. The two 16 ohm woofers in parallel should get you in the ballpark, in any case. When you described helper woofer, I was expecting that you describing a .5 woofer system which is a popular method of dealing with something called baffle step. In this case, I don't think this is a viable option.
 
At this point,if it can be made to work properly.I would prefer 1 SP15 per box. I bought the working pair because they were about $100.00 more than getting the ones I had re-coned. And they are genuinely mint !
I will see what telex offers.
Thanks again.....
 
dnewma04 said:
BTW, it appears to be 2 8 ohm drivers in series, a single SP15 at 16 ohm may work ok.
Click to expand...

Thanks,sorry I didn't locate that myself. I'm still learning my way around the telex site.
Yeah,it sounds OK now...way better than OK actually. I just want to make sure they are all they can be.After all, I would like to haul these to a gathering that is taking place somewhere around here (Novi) in May. :yes: and there will be some knowledgeable individuals in attendance.
So far,lots of fun...and the volume levels that can be obtained are pretty incredible. The horns do seem to be pushing the woofer around a bit.
Andrew(AP1) suggested L- pads to control them !
:D
 
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