Impendance rise and amp output
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Gold Member Username: SomedonniedudeIllinois United States Post Number: 1441 Registered: May-07 | This is something that has been on my mind latley. My 15" SPv.2 is a dual 2 ohm sub, so I need a 1 ohm stable amp (duh!), but my coils read in at 2.2-2.3ohms each so my amp would be seeing around a 1.15 load (before rise), does that seem odd? Now for what I'm getting at. I'm looking into a 1200w 1 ohm stable amp. Some of the amps Im looking into do 600w @ 2 ohms, while others will do around 900w @ 2 ohms. Now I know that most coils have a lower RE than claimed coil impedance to make up for imp rise. Lets say I get 1.5 ohm average after rise (I know it will vary between frequency's), Is there any way I might tell a difference between the amp that does 600w @ 2 ohms compared to one that might do 900w @ 2 ohms, both rated equally at 1200w @ 1 ohm. I guess I should go see what its reading on music to see how much rise I actually get. Am I just being too @nal, or is this something to possibly consider when choosing an amp? |
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Gold Member Username: Denali_on_22sI get Bucks like Milwa... Post Number: 5398 Registered: Feb-06 | i had a similar question to this as well, man. the rise, of course, depends a lot on on the box. NORMALLY the larger the box the higher the rise, or so i've heard. your best bet would be to see what rise you're getting playing music and that would tell you what you need to know. you are hardly ever going to see full potential out of that amp (unless you're constantly playing below box tuning) so i would definitely go with the 900 @ 2 ohms amp. |
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Gold Member Username: Nd4spd18Northwest PA Post Number: 7390 Registered: Jul-06 | Speakers are a reactive load, the impedance changes constantly depending on what frequencies are played. You can not get an accurate measurement of it with the DMM. So to answer your quesiton yes you are focusing too much on something that ain't going to matter. |
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Gold Member Username: SomedonniedudeIllinois United States Post Number: 1442 Registered: May-07 | One more question, does it seem odd that my coils measure so high? Are they heavily worn by any means? It's hard to find the specs on this sub so I don't know what they are. ED replied to my email saying they never did have the specs since they were never tested, which is a bunch of B.S. |
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Gold Member Username: TejcurrentPost Number: 1281 Registered: Apr-07 | most 1 ohm coils are .7, 2 ohm are 1.4, and such. It's normal for the coil to measure lower, higher generally means some abuse. |
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Gold Member Username: SomedonniedudeIllinois United States Post Number: 1444 Registered: May-07 | I bought it used off ebay, so I have no idea what this thing has or has not been through, but got an insane price so I figured if it was junk the motor and basket were worth it . |
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Gold Member Username: •cam•BC Canada Post Number: 2413 Registered: Nov-06 | I doubt you'll notice the difference. I abused my MAWs a bit when I first got them and they read a little high but it's not audible. |
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Gold Member Username: Nd4spd18Northwest PA Post Number: 7393 Registered: Jul-06 | I have seen plenty of subs measure higher on the DMM than rated impedance. That is measuring resistance though, impedance changes like I said. If you want an example of it push down on the cone with your DMM hooked up to the coil. |
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Gold Member Username: SomedonniedudeIllinois United States Post Number: 1449 Registered: May-07 | Cool, just wanted to make sure everything was A-O-K. I went ahead and bought one of Robs kx1200.1's Anyone know of a good place to read up about this sorta stuff? Thanks guys for the responses, this is why I love this forum  |
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Gold Member Username: Nd4spd18Northwest PA Post Number: 7396 Registered: Jul-06 | www.bcae1.com That site could be used as a car audio knowledge test, it's that comprehensive. |
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