I have a 12" RE SE series sub. It is rated at dual 4 ohm, but it can be wired for 2 ohm. So I bought an amp to wire at 2ohm. Go to get it installed and they call me and say the voltmeter only reads 3 ohms. So I take it home and use my own voltmeter, and it only gives me 3 ohms. So i figure, lets throw a wire across the terminals. I wired it in parallel and tried again, but still only got 1.5 ohms (1.5x2=3, ya know). What would be wrong with the sub that it would do that?

 

run it at 1.5ohms, less resistance

 

your sub is fine. 3 ohms is your sub's Re. My brahma is rated at dvc 2 ohms, but they really measure 1.6 each.

 

Wiring in parallel would drop the ohm load, not multiply it by 2. So parallel 'should' give you 4/2=2 ohm load. Series 'should' give you 4x2=8 ohm load. So although Im a little confused as to what you did, I say best bet is call RE and see if this has happened or if they are aware of whats goin on

GL
Kevin

 

on second thought listen to ascendant, i didnt read the specs i just typed a reply.

and what amp are you using camry?

 

hmm...i just checked RE's website looking for the T/S parameters of the SE sub. they don't have the full list. it should tell you the Re rating is for the sub. I'm guessing it'll be around 3 ohms like you mentioned.

 

well, i have an Alpine Mrd-m501, which can be used at 2 and 4 ohms, but you guys are saying my sub should be 3 ohms????

 

and also, I see that Re rating at the top of the T/S section and it says 2.89 DVC. I really dont know what any of this means, so what is "Re" and what does the value represent. And if it is supposed to be that 3 ohms that it read, will my above mentioned amp work?

 

yeah...2.89 and 3...close enough.

i think your amp will be fine. i'm running my brahma at 4 ohms, bridging my amp to power it. my amp is only stable down to 4 ohm when bridged, but it's really seeing a bit lower than that. it gets a little warm, but it hasn't cut out on me so far.

Re is the DC resistance of a voice coil. most of the time, it'll be a bit lower than the advertised or published resistance.

 

Its also just a thermal rating, whereas when theres a load on it, it will vary. Your amp should work fine.

 

either way if its 3 ohms everything is fine. have you wired it up and listened to it?

 

nah, i havent listened to it yet, the people who were installing it didn't want to hook it up for fear that they might screw up my equipment. So the verdict seems to be that 3 ohms is correct and that my amp will work if i run it at 2 ohms?

 

can anybody confirm the fact that if i wired the sub in parallel, I could run my amp to it at 2 ohms and not have a problem even though this sub reads 3 ohms on the voltmeter.

 

it will be fine. frankly, if that shop didn't know about a sub's Re rating, or T/S parameters for that matter, i'd take it somewhere else to have it installed.

 

ok then, thanks guys

 

I'd take it to a different shop, though. Any installer worth a dam should know the difference between Z nom. and Re.

 

could you explain that difference to me, I'll admit I'm not too bright when it comes to this stuff, but I'd love to learn

 

A speaker is fairly complex in that there are both mechanical and electrical components that effect overall system impedence. If you study an impedence curve you will see a sharp peak at the low end due to resonance (fs), as the frequency rises the voice coil inductance takes over and increases the impedence. There is a portion of the curve between the resonance peak and the indutive rise that should come down and equal the DC resistance of the coil, this is Re. The impedence will never drop below this.

 

thanks a lot man, ya learn something new everyday