Impedance help

[cfp 10+ year member]

I've just installed an old amp for my front speakers and one of the channels is fuzzy/crackly but the other is fine, it is also fine in the bridge mode.

Have tested the amp with another speaker and it does the same thing. So assuming that its the amp that is broken would it be possible to wire the speakers in to the same terminal be it on a single channel or bridged? If so which way would be best?

Technical specs

nominal output power (B+=14.4V) 2x80W/1x210W on 4Ohm

nominal output power (B+=14.4V) 2x112W on 2Ohm

loudspeaker impedance (stereo) 2-8Ohm

Speaker 60W RMS

impedance 4Ohm

Click to read more...

 

[disturbed471985 5,000+ posts]

Eww NM did not notice amp wasen't 2ohm stable.

 

[Kangaroux 5,000+ posts]

If you did that your speakers would be wired in essentially bridge mode, which would mean it's in mono.

Are there separate controls for each channel? if so, make sure the settings for the crackly channel are correct.

 

[cfp 10+ year member]

Thanks for your reply, mono isnt a problem, im just looking for a fix until i can afford to buy myself a new one. There are no seperate controls for each channel.

So would i go about this by putting both speakers into the same output on the amp?

Also how would i go about setting the correct gain using a multimetre am i looking for a 60w or 120w output.

 

[Kangaroux 5,000+ posts]

Thanks for your reply, mono isnt a problem, im just looking for a fix until i can afford to buy myself a new one. There are no seperate controls for each channel.
So would i go about this by putting both speakers into the same output on the amp?

Also how would i go about setting the correct gain using a multimetre am i looking for a 60w or 120w output.

well your speakers are 8 ohms, which means if you wired them up to parallel they would be brought down to 4 ohms. so, wire them in parallel and wire them so they're bridged.

your speakers call for 60w each on a 4 ohm load. to find the correct AC voltage that should be coming from the speaker outputs, you do sqrt(2 * 60 * 4ohms) which equals 22v.

 

[cfp 10+ year member]

Am i missing something my speakers are 4 ohms, or are they 8 ohms because they are wired in parallel?

 

[Kangaroux 5,000+ posts]

Am i missing something my speakers are 4 ohms, or are they 8 ohms because they are wired in parallel?

you said in your original post that the speakers were 2x 8ohms. if they are 4 ohms your only choice really is to wire them in series back up to 8 ohms. you could try 2 ohms but it would prob just kill your amp

 

[cfp 10+ year member]

Sorry i guess that i wasnt very clear;

these 3 values are from the amp user manual

nominal output power (B+=14.4V) 2x80W/1x210W on 4Ohm

nominal output power (B+=14.4V) 2x112W on 2Ohm

loudspeaker impedance (stereo) 2-8Ohm

and the speakers are 60W RMS with an impedance 4Ohm each

The amp (mutant nw280sp) came with a user guide how to wire it up to 2x4ohm subwoofers, the userguide recommends that its wired up in a 2ohm bridge and powers 300W RMS mono.

So would i just do sqrt(2 * 60 * 2ohms) = 15.5v?

 

[Kangaroux 5,000+ posts]

Sorry i guess that i wasnt very clear;these 3 values are from the amp user manual

nominal output power (B+=14.4V) 2x80W/1x210W on 4Ohm

nominal output power (B+=14.4V) 2x112W on 2Ohm

loudspeaker impedance (stereo) 2-8Ohm

and the speakers are 60W RMS with an impedance 4Ohm each

The amp (mutant nw280sp) came with a user guide how to wire it up to 2x4ohm subwoofers, the userguide recommends that its wired up in a 2ohm bridge and powers 300W RMS mono.

So would i just do sqrt(2 * 60 * 2ohms) = 15.5v?

yea that would work