Amps, Subs & OHMs

toot · Post by **toot** » Sat Sep 27, 2003 12:29 pm

Hi all.

Ordered a Rockford Fosgate RFD-2212 from car audio direct but they have sent me an RFD-2112. They are basically the same except the impedance on the 2112 is 2 OHMs rather than the 4 OHMs on the 2212. My amp is bridged and the manual claims it is 4 OHMs when bridged. Will the sub work on it is the question or should I send it back and get my 2212?

toot · Post by **toot** » Mon Sep 29, 2003 7:14 pm

Hello again.

So does no-one know or does no-one care?

Post by **Lyndon** » Mon Sep 29, 2003 7:31 pm

not a clue soz m8

MattB · Post by **MattB** » Mon Sep 29, 2003 7:43 pm

I was kinda hoping someone else would reply!!

I can't find those amps on CADs site anywhere. If it's definitely outputing 4Ohms and you need 4Ohms then that's fine... but to be honest it may be best to send it back & get the one you originally wanted so you can be sure.

Out of interest, what impedance does the 2212 have when bridged?

MattB · Post by **MattB** » Mon Sep 29, 2003 7:44 pm

D'OH!

Just realised that you're talking about subs and not amps!

Definitely get the 4Ohm speaker - don't power a 2Ohm speaker with a 4Ohm amp.

BTW, bet your setup sounds absolutely mint.. always wanted an RF setup!

Cayman 206 CC · Post by **Cayman 206 CC** » Mon Sep 29, 2003 9:17 pm

Yeah, like Matt says, id go 4 the 4 0hm's RFD 2212 seeming as your amp is bridged but it really depends what amp it is and what yor running off it, weather it subs, or speakers and how many! If u have a look in the i.c.e section (pics of my ice) ive put a couple of pics in there of my Rockford Fosgate set up with
my set up at 4 ohms. Ive got the amp (Rockford Fosgate 500x) running the two 10" subs and the rockford components in the front doors and it sounds spot-on!
It may not be what u wanted to hear but i think the 4 ohms is much better.
U could always ask your local ice stockest what they think!!

Hope this has helped!!

toot · Post by **toot** » Tue Sep 30, 2003 12:34 am

Thanks MattB, I was a bit confused by your first post

I'm running a Kenwood 7201 amp for the sub and the sub is the only speaker attached to it. Its putting out an RMS of 460W at 4OHMs (or so the manual says) and the RFD-2212/2112 is 500W. I ordered the 4OHM 2212, as I said, and got the 2OHM 2112 but they are both the same price so its no hassle to swap. It just means I have to fork out for P&P to get it back to caraudiodirect.co.uk and wait AGAIN for the 2212 (its taken them about 3 or 4 weeks to get this one in stock). Is this really the best thing for me to do? If it is, then I'll do it but if its just for the sake of it, I'd rather use what i have if it isn't going to cause a problem.

So what would happen if I put the 2OHM sub on a 4OHM amp?

By the way Cayman, where abouts are you in Donnie? My girlfriend lives in Thorne. My little baby had some work done in the Dixons/Peugeot garage up there a couple of weeks ago.

toot · Post by **toot** » Tue Sep 30, 2003 12:54 am

Just been reading the 2212/2112 manual. Although its a 2OHM sub, it has a load of diagrams showing different set-ups and its confusing me. Here is the single sub setup part of the diagram:

The (1) signifies that its a single speaker. Now, do I take this to mean that the 2OHM speaker will actually provide a 4OHM load when used on its own and that the 4OHm provides a 2OHM load? If thats the case, then is the 2OHM not the one I want? God, I find this stuff so confusing!

I would guess Cayman is using the top left setup on this diagram based on whats been said:

MattB · Post by **MattB** » Tue Sep 30, 2003 9:56 am

Ah if the speaker is bi-wired then indeed you can run the 2Ohm speaker from a 4Ohm amp as explained in the diagram. I don't know how his affects the RMS output though...

toot · Post by **toot** » Tue Sep 30, 2003 10:53 am

So I can use it then? Luvvly jubbly. Do you reckon there is a chance it will reduce output though? If so, I'll be swapping it for the 4OHM one. Anyone out there got any idea if my RMS will be affected if I go ahead with this setup?????

By the way, what is Bi-Wired exactly then Matt?

Cayman 206 CC · Post by **Cayman 206 CC** » Tue Sep 30, 2003 6:51 pm

Those diagrams have lost me toot! Sorry i cant hlp u any more, but if those 2 stereos are the same id go 4 the 1 with 4 0hms then at least u know uve got the 1 u wanted or if u just want to get it fitted go 4 the 1 uve got. Its up 2 u really, just my choice.

By the way i live at Askern, only about 4 miles from Thorne.
Ive been to Thorne fire station a few times so i know that area quiet well.

Ill have to have a look at your set-up the next time your up in Donny!

MattB · Post by **MattB** » Tue Sep 30, 2003 7:45 pm

By the way, what is Bi-Wired exactly then Matt?

It means that there are two sets of paired wires going to the speaker, as per the diagrams up there - ie two negatives and two positives into the coils.

toot · Post by **toot** » Tue Sep 30, 2003 8:32 pm

Right, got an email back from caraudiodirect and they reckon that the sub I've got is actually better for my setup than the 4OHM one. I don't see any reason they would fib as they are not losing out on price with the 2 subs being the same Â£. They even sent me a diagram of how to set it up which looks pretty much the same as the one I've posted here.

Have asked about the RMS though. Should get a reply soon. i don't think it will affect it so I'll be getting it installed this weekend at the same time as my neons in the boot and my flashing door pin thingies

This means I'll have a 12" SPL Mule sitting around looking for something to do

Cayman, piccies lost me too. Not sure what wire I use to connect the 2 points that aren't attached to the amp, MattB, you seem to know about this?? Will be up in Donny next weekend, I think, Cayman getting my new 17" wheels fitted along with a new back box. Let me know if you want to hook up and we can compare wattage. I'd love to know what other CC'ers think of my 7x10's hanging from the windbreak

Cayman 206 CC · Post by **Cayman 206 CC** » Tue Sep 30, 2003 9:07 pm

Yeah that would be great. Im on days next Saturday but off on Sunday so could maybe meet up sometime then if your not busy. Let me know if u can? I wouldnt mind having a look at some other modded 206cc'c as i dont really get to see that many local, then ill be able to check out the new back box and alloys if there fitted by then, and see what other goddies i can do 2 mine!

Cheers Rich. Might see u soon then!

MattB · Post by **MattB** » Tue Sep 30, 2003 9:38 pm

Toot, basically if the diagram is correct you connect the +ve from the amp to one of the +ve terminals on the speaker. The connect the -ve from the amp to the OPPOSITE -ve on the speaker (ie not the one next to the +ve you've connected.

Then use some wire identical to the amp to speaker wires to connect the remaining +ve and -ve on the sub together.