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Post by ThomasW on Nov 19, 2008 20:40:06 GMT -7
should i get the 2 ohm or 4 ohm drivers? 4 ohm
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Post by happyhour on Nov 20, 2008 4:45:30 GMT -7
Just for some info. My manifold for 2 Fi 18's has opening of 12.5x20.5 internal demension. Made it to fit between the studs. My manifold external demensions were 23.5x23.5 and you can see how tight the mounting of the 18 was. And just some food for thought, I have the 4ohm 18's, but I also have an ep2500. So I am feeding them about 650watts and they are happy, if you go 4 ohm with the ep1500 you will only be getting 400 watts each. 2 ohm may be the way to go for you IMHO. That would give you 700 each and some flexibility. Any thought's on that Thomas?
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Post by slovenian6474 on Nov 20, 2008 5:36:47 GMT -7
I was originally thinking 2ohm because of my amp. I'm pretty sure I'm not going to be adding any extra drivers after the 2 because it's going to be tight to even get the 2 installed.
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Eskimo
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Posts: 143
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Post by Eskimo on Nov 20, 2008 9:11:23 GMT -7
If you're absolutely certain you'll only have 2 drivers, then yes, get the 2ohm units, wire them in series, and present the amp with a 4 ohm mono load.
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Post by ThomasW on Nov 20, 2008 14:43:43 GMT -7
Any thought's on that Thomas? I'm not a fan of 2 ohm loads and I'm not a fan of bridged amps. Bridging doubles the distortion, and low impedance loads make the amps work hard. So what to do? Spend the extra $50 for a EP2500, and buy 4 ohm drivers IF one is using only 2. If the IB is going to contain 4 drivers buy the 2 ohm versions.
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Post by happyhour on Nov 20, 2008 16:00:06 GMT -7
I would agree. I have my ep2500 running 4ohm stereo and don't have to worry about any overheat issue, plus I have the flexibility to add more and drop down to 2ohm, if I want.
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Eskimo
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Posts: 143
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Post by Eskimo on Nov 20, 2008 19:59:11 GMT -7
Going from .028% THD at stereo 4ohm to .028% THD with a mono 8ohm load really doesn't seem to be doubling distortion. I'll agree though that going from stereo 8ohm to stereo 4 ohm does double the THD. However, even dropping to 4ohm mono is only .0461%THD - Those numbers are really, really, really low...
One advantage of using the amp bridged is you never have to worry about one speaker getting driven ever so slightly harder than the other - which would have to create some type of miniscule issue itself, if we're talking about distortion numbers well below a tenth of a percent..
BUT, with the price difference in the EP1500 and EP2500 being so small, I'd agree, get the bigger one and let it loaf along, giving you lots of headroom.
Happyhour - 2ohm stereo is the same load on the amp as 4ohm mono, which you could also do if you added the same load that would give you the 2 ohm stereo, so there's no flexibility lost..
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Post by ThomasW on Nov 20, 2008 20:56:52 GMT -7
Chasw98 is a personal friend of mine, so I'm quite familiar with his measurements.
One needs to keep in context the fact that his measurements are made using a load bank
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Post by jman on Nov 20, 2008 21:03:18 GMT -7
I noticed a few days ago that my EP2500 is running very hot and this is with the fan mod'd to blow out rather than vacuum in (which is idiotic).
If I touch the top it's pretty warm and the 4 screws on top that go into the heatsink are burn your finger hot after a couple seconds.
I am running 2 ohm stereo. I'm thinking of trying 8 ohms bridged to see if the amp runs cooler.
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Post by chrisbee on Nov 21, 2008 1:36:38 GMT -7
I noticed a few days ago that my EP2500 is running very hot and this is with the fan mod'd to blow out rather than vacuum in (which is idiotic). If I touch the top it's pretty warm and the 4 screws on top that go into the heatsink are burn your finger hot after a couple seconds. I am running 2 ohm stereo. I'm thinking of trying 8 ohms bridged to see if the amp runs cooler. That's odd. I never got much above ambient even after I left a wide gap by revering the shroud when I fitted a slow fan. An hour of 110dB bass heavy car audio and rock music produces barely perceptible warmth. I'm running 4 ohms per channel stereo.
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Post by slovenian6474 on Nov 21, 2008 7:27:39 GMT -7
Hmm, I'm restricted to 2 drivers as long as I'm on this house (just bought it, not going anywhere soon). If the EP2500 is only $50 more, I think i might just go with that.
Eskimo: What's the internal dimensions of your manifold? I ask because i think i may invert the one driver like you have. I have my water shutoff located behind this sub and don't want to block it completely.
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Eskimo
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Posts: 143
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Post by Eskimo on Nov 21, 2008 8:53:46 GMT -7
it's 12x20x20 (and needs to be bigger than the 20" as noted above, but the 12" is plenty of depth for the flipped driver.
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Post by slovenian6474 on Nov 21, 2008 9:35:23 GMT -7
Excellent. Thanks.
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