serega

Basically i was just about to buy a subwoofer tommorow and i have come across the OMH term which is as i understand an electrical resistance of a current, i.e the bigger the OMH the less wattage is able to come through - is this right ?.

Now my amplifier is a mono channel DLS CAD1000 specs as :
1 x 350 watts @ 4ohm/ 1x 700 watts @ 2ohm/ 1 x 1000 watts @ 1ohm
Built in low pass filter (variable 50 – 125Hz), phase shift controller, high level input with autostart, class D operation.

The first question is - are amplifiers required to be set to a certain omh or do they adjust automatically depending on what speaker they supply ?

The second question is - if i get a subwoofer that is rated at 1omh, am i correct to understand that i will need to get one for 1000w and 700 watt if its at 2omh?

Now when looking for subwoofers i have noticed that most of them come as a 4omh, but some of them- for example this one : http://caraudiosecurity.com/shop/pro...s_id/5598.html
says :Impedance: 2-ohms DVC, can be wired into 1-ohms or 4-ohms

Now, the interesting part for me is "can be wired into" - how do you wire them to become 1omh and can any other sub be wired to become less omh ?

dunx

iTrader: (3)

It's an ohm by the way ! Pedantic I know !

In terms of power, more ohms require less current for a given power output, so at home 8 ohms is common, loads of power !
In car gear is usually 4 ohm as there's only 12 V to drive it.... subs are greedy so the drop to 1 ohm needs four times the current a 4 ohm speaker would need.

The amplifier is a simple soul, it just feeds the load as best it can, so no settings to do....

Yes you are right 1 ohm speaker = 1000 W

The speaker has two 2 ohm voice coils,

So if you connect + to - and + to - and it's 4 ohms total
Amp+______+ COIL 1 - ____+ COIL 2-_____-AMP


But if you connect ++ and -- they are in parallel so it's 1 ohm

AMP+ <----+ COIL 1 - ------> -AMP
........<----+ COIL 2 - ------>

If the amplifier is rated into a 1 ohm load it's capable of driving it !

The usual way is to buy two speakers and wire in parallel, most people buy two cheap ones for under £100.... I bought one DVC (dual voice coil) for £200 so I didn't need a large box !


Don't try less than 1 ohm Tho' current loads will be enormous....
I find 500 W RMS into an 800 W RMS DVC speaker is nice for volume and doesn't need vast amounts of electrical power to run it ! But it is capable of dismantling your car in time....

Hope this helps,

DunxC

Get advice on cable to wire the amplifier up to the battery, and fit a fuse as close to the battery positive as you can get for safety....

Trout

iTrader: (1)

I am not sure of what 'wired' into means however it is never as simple as it looks. The resistance of a speaker varies with frequency so a speaker rated as 4ohms is giving an average resistance that may vary from 1 to 6, for example.

Amps have a very hard time driving very low resistance (anything less than 4 is low). A perfect amp will double the power everytime the resistance is halved, however very few amps can do this. Hi-fi amps are usually designed to run into 8 ohms and these amps will struggle to double into 4 ohms, never mind double again into 2 ohms!!

The other thing about rating of speakers and amps is that speakers can usually take a huge amount of power as long as it is 'clean' i.e. it is a quality signal and there is no clipping of the amp. A speaker rated for 100w could easily handle a quality, non-clipping input of 500w. The challenge is that there are very few hifi amps capable of delivering a true 500w and not be clipping or adding distortion artefacts.

rgv_stu

thats the reason i went for PA gear for my hifi amplification i have 2 sets of speakers in parrallel on a Crest Audio 1.4Kw amp as you state a clean signal doesnt destroy a speaker rated at a lower power.