Im not quite understanding ohms. How do I run a stereo in 2 ohms. If someone could explain ohms to me it would be greatly appreciated. also if I have a 1 channel amp how do I run 2 subs off it?
Replies (3)
swez on 06/20/2004 09:47:51
Ohms are a unit of resistance. Speakers are rated in terms in watts of power they can dissapate and the resistance of the speaker changes constantly based on frequency. To simplify wiring to the average non-techie, speaker makers rate their products in nominal OHMIC value. A common aftermarket speaker is usually rated at 4 ohms for simplicity.
Also, when using multiple speakers, we get a different ohmic value that the amp sees as a "load". For example, we have 2 subs. Each are 4 ohms nominal by themselves. We can wire them in parallel or series to the amp and get very different load results.
Series wiring:
Two subs, wire in series. Each are 4 ohms. The amp will see a load value of: (4+4) = 8 ohms.
Amp Pos <------wwww------wwww------> Neg Amp terminal.
==================================================
Parallel wiring:
Two subs, wired in parallel. Each are 4 ohms. The amp will now see a
load value of: (4/2) = 2 ohms.
Amp Pos <-------wwww---------> Neg Amp terminal
Amp Pos <-------wwww---------> Neg Amp terminal
===================================================
See how that works? By leaving the speaker ohmic value fixed at 4 ohms, we can change the load that the amplifier sees, by using series or parallel connections. This is just the basics for now. Things can get a bit more complicated when using dual voice coils. But more flexability is possible with the DVC as well.
===================================================
Your question: "If I have a 1 channel amp how do I run 2 subs off it?"
The answer depends on the amp and subs you have. Most 1 channel amps (MONO) meaning one channel, have a load range in ohms the amp can safely handle. In most cases, a MONO amp, is generally stable with a 2 ohm load. The specs on the amp, will also tell you the power ratings (in watts) the amp can supply at different load values.
Example:
75 watts continous (RMS) @ 8 ohms
150 watts continous (RMS) @ 4 ohms
300 watts continous (RMS) @ 2 ohms
===================================================
This is how we match the amp to subs, or subs to amp for maximum output watts and stability of the amp at a given load range.
Instead of hashing out an issue with a bunch of words or math equations, (which I tend to do a lot) we can simplify the process a lot by knowing what gear you have now or wish to buy soon. Knowing the Make, model and general specs of amps & subs, can easily help you get wired for sound.
Say more Aussie friend and welcome to CK,
Swez
Munchiesyumm on 06/20/2004 15:22:07
Here are some wiring digrams to help you on the job!
http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/learningcenter/car/subwoofers_wiring.html?view=all
You didn't list what subs you had although this site has a wiring diagram for most subs. I am sure you will be able to match up which is right for you!.
good luck.
vt_low_low on 06/21/2004 00:10:19
Thanks for your help guys. I have just bought an alpine mrd-m1000
amp rated at 1x500 rms @ 4 ohms and 1x1000 rms @ 2ohms. As of yet I have not bought new subs for it. I currently have 2 MRV-T420 amps running 2 pioneer TS-W1241C. I am now only running 1 sub and the other amp is powering boston acoustics pro series 6.5 splits. Coming in the mail are focal splits (to be run off the other t420) and a stinger 3 farad. Im having trouble deciding which subs I want. So any suggestions are welcome.
Replies (3)
swez on 06/20/2004 09:47:51
Ohms are a unit of resistance. Speakers are rated in terms in watts of power they can dissapate and the resistance of the speaker changes constantly based on frequency. To simplify wiring to the average non-techie, speaker makers rate their products in nominal OHMIC value. A common aftermarket speaker is usually rated at 4 ohms for simplicity.
Also, when using multiple speakers, we get a different ohmic value that the amp sees as a "load". For example, we have 2 subs. Each are 4 ohms nominal by themselves. We can wire them in parallel or series to the amp and get very different load results.
Series wiring:
Two subs, wire in series. Each are 4 ohms. The amp will see a load value of: (4+4) = 8 ohms.
Amp Pos <------wwww------wwww------> Neg Amp terminal.
==================================================
Parallel wiring:
Two subs, wired in parallel. Each are 4 ohms. The amp will now see a
load value of: (4/2) = 2 ohms.
Amp Pos <-------wwww---------> Neg Amp terminal
Amp Pos <-------wwww---------> Neg Amp terminal
===================================================
See how that works? By leaving the speaker ohmic value fixed at 4 ohms, we can change the load that the amplifier sees, by using series or parallel connections. This is just the basics for now. Things can get a bit more complicated when using dual voice coils. But more flexability is possible with the DVC as well.
===================================================
Your question: "If I have a 1 channel amp how do I run 2 subs off it?"
The answer depends on the amp and subs you have. Most 1 channel amps (MONO) meaning one channel, have a load range in ohms the amp can safely handle. In most cases, a MONO amp, is generally stable with a 2 ohm load. The specs on the amp, will also tell you the power ratings (in watts) the amp can supply at different load values.
Example:
75 watts continous (RMS) @ 8 ohms
150 watts continous (RMS) @ 4 ohms
300 watts continous (RMS) @ 2 ohms
===================================================
This is how we match the amp to subs, or subs to amp for maximum output watts and stability of the amp at a given load range.
Instead of hashing out an issue with a bunch of words or math equations, (which I tend to do a lot) we can simplify the process a lot by knowing what gear you have now or wish to buy soon. Knowing the Make, model and general specs of amps & subs, can easily help you get wired for sound.
Say more Aussie friend and welcome to CK,
Swez
Munchiesyumm on 06/20/2004 15:22:07
Here are some wiring digrams to help you on the job!
http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/learningcenter/car/subwoofers_wiring.html?view=all
You didn't list what subs you had although this site has a wiring diagram for most subs. I am sure you will be able to match up which is right for you!.
good luck.
vt_low_low on 06/21/2004 00:10:19
Thanks for your help guys. I have just bought an alpine mrd-m1000
amp rated at 1x500 rms @ 4 ohms and 1x1000 rms @ 2ohms. As of yet I have not bought new subs for it. I currently have 2 MRV-T420 amps running 2 pioneer TS-W1241C. I am now only running 1 sub and the other amp is powering boston acoustics pro series 6.5 splits. Coming in the mail are focal splits (to be run off the other t420) and a stinger 3 farad. Im having trouble deciding which subs I want. So any suggestions are welcome.
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