Confusing Ohms

[Rob22]

Just ordered the MRV 345 Alpine amp and the 1222D sub, my question is what difference is there between the 1222D and the 1242D sub, I know its the ohm rating and thats resistence right? But why are they different and does it matter which one you have. Thanks
Rob

 

[Dink]

yeah it does matter

the "resistance" of the speaker with determine the output power of the amp

both those speakers have two voice coils you need to connect them in either a parallel or series configuration

if your looking to run one off that amp bridged you need the one with a dual 2 ohm voice coil and connect them in series

 

[jamesy]

i think your want the dual 4ohm fella as the rear channels on that amp bridge at 2ohm my amp came in under rated and happens to be 4x100wrms @ 4ohm so rear channels bridged chuck out 400wrms @ 2ohm if you go for the dual 2 your only be able to present either a 1 or 4 ohm load to the amp alpine's dont like to be run at much less than 2 ohm even class D unless your just burping for spl and 4 ohm you would just be getting half the power you could potentially be getting(you would want the dual 2's if you were looking at running two subs)

 

[Dink]

nice one jamesy

you need a dual 2 ohm sub if your going to run it of the rear channels bridged

as that amp will prolly catch fire if you try to run it @ 2 ohms bridged

 

[White16valver]

lol

That would be impressive!

 

[Rob22]

lol ok now im getting worried..
This is the system:
http://www.caraudiocentre.co.uk/product.asp?product=21513 HU
http://www.caraudiocentre.co.uk/product.asp?product=20266 Fornt comp
http://www.caraudiocentre.co.uk/product.asp?product=20266 Rear coax
http://caraudiosecurity.com/shop/product/products_id/3261.html Subhttp://caraudiosecurity.com/shop/product/products_id/3387.html Amp
http://caraudiosecurity.com/shop/product/products_id/2637.html Wiring

Spoken to crazy clio in a previous thread and i think im going to run the front comps and the sub off the amp then the back speakers off the HU
Do i need the 2 or 4 Ohm sub ????:approve:
Thanks, Rob

 

[Dink]

dual 2 ohm as said above

 

[White16valver]

The link for the sub doesn't say what it bridges at.

If it bridges happily at 4 ohm then get the Dual 2 ohm sub and wire it in series to get 4ohm.

If it bridges and will run at 2ohm then get the Dual 4 Ohm and wire it in parallel to get 2 ohm.

*edit* posted at the same time as dink - for safety I'd get the Dual 2 and run it at 4 ohm!

 

[Dink]

you need to look at the the amp to see what the minimum load it is able to run in BTL mode

 

[White16valver]

http://www.caraudiodesign.co.uk/product_info.php/pName/alpine-mrvf345-432-channel-power-amplifier

seems to suggest 4ohm bridged, giving 300wrms, as does:
http://cgi.ebay.com/ALPINE-MRV-F345-4-CHANNEL-AMPLIFIER-CLASS-A-B-CAR-AMP_W0QQitemZ300033599431QQcmdZViewItem
though that one is ebay... lol

 

[Dink]

yep exactly:approve:

so a dual 2 ohm sub is needed and run the voice coils in series

 

[White16valver]

Agreed :approve: lol

 

[White16valver]

Dink - did you see on TA someone's selling secondhand 2500D's (I think that's right?) for £325! If I had a) the subs to cope with it and b) the money, I'd be right in there... lol

 

[Dink]

nope mate aint been on there for a while

only tend to go one there to ask really obscure questions about car audio lol

 

[Rob22]

Cheers guys 1222d it is, thanks for the help
Rob

 

[jamesy]

nice one jamesy

you need a dual 2 ohm sub if your going to run it of the rear channels bridged

as that amp will prolly catch fire if you try to run it @ 2 ohms bridged

you nugget the rear channel on this amp bridge at 2ohm you want to question it ive been doing it for about six month's and it is stable trust with the protection these babies have it would shut down the moment it got a bit too hot let alone catch fire (oh i see you've been on alpines site and copied their diagramLOL)

 

[Dink]

so it's 1 ohm stereo stable too lol

so your getting about 600wRMS from the rear channels bridged?

 

[Laura]

jamsey do you know andrew?

 

[jamesy]

jamsey do you know andrew?

pm replied