Rewiring 8ohm to 4ohm

[Toasted]

I did a little search before posting, couldnt find what i want.

I'm considering a Mesa walkabout + Ashdown 4x8mini rig.

Currently the 4x8 is 8ohm, is there a way it can be rewired to be 4ohm, and draw the full 300 watts from the walkabout.

Whilst im at it, sounds like a great rig... dont it

 

[BillyB_from_LZ]

This thread started just today...

http://www.talkbass.com/forum/showthread.php?t=128994

Basically, you can't rewire to make the change you want. Read what I wrote to Scotty in the referenced thread to get the good news...

 

[JSCHRO7376]

You can't rewire your cab. You would have to purchase 4 new speakers with 16 ohms each, that'd be the easiest but costly way.

 

[Toasted]

thanks. not i feel stupid. not the first time, wont be the last time

 

[Suburban]

Makes no sence, fellas!
If you put in a gadget with an impedance parallel to another gadget with an impedance, you have a new total impedance. Basic electrotheory.

So, if I have an 8ohm woofer, and put in an 8ohm impedance in parallel, I have a total impedance of 4ohms.

The possible problem I may face is, that the two impedances have different frequency dependencies. Like if you put in two woofers of different specifications...

 

[BillyB_from_LZ]

True, but...

A woofer's "rated" impedance is the nominal impedance. There are probably only one or two freqencies where the voice coil is truly 8 ohms (or whatever). However, we use the nominal impedance as a worst case value.

I suspect that some woofers can exhibit an impedance below their rated nominal impedance...hence the Acme-Carvin shutdown problem that we read about occassionally.

The point of this thread is that you can't take four 8 ohm woofers and interconnect them (in a normal, equal power distribution configuration) to create a 4 ohm nominal impedance...you either get 2 ohms (parallel), 8 ohms (series/parallel) or 32 ohms (series).

 

[Spanky]

The point of this thread is that you can't take four 8 ohm woofers and interconnect them (in a normal, equal power distribution configuration) to create a 4 ohm nominal impedance...you either get 2 ohms (parallel), 8 ohms (series/parallel) or 32 ohms (series).

So if you start with 16 ohm woofers then you can wire 4 of them to obtain your 4 ohm cab...did I understand this correctly?

 

[Frank Martin]

So if you start with 16 ohm woofers then you can wire 4 of them to obtain your 4 ohm cab...did I understand this correctly?

Yep, it you wire them all parallel