Converting a 4 Ohm cab to 8 Ohm. Worth it?
 

After posting and reading a bunch of things on impedance, I feel that I am now an expert!!!!! ok, maybe not.

But, here's my idea. Please offer insite and thoughts.

I have a really nice Peavey 1 x 15, 4 ohm (500w?) cabinet. I actually would love not to eff with it. BUT, I need a 1 x 15, 8 ohm cabinet and, not that it's a money thing, but really, how many cabinets is one person going to keep hanging around?

What I'm thinking is to have a dual 1/4" input on the back of the cab where one input goes direct to the speaker (4 ohm) and the other input interrupted with a 4 ohm resister in series to make an 8 ohm.

Is the heat disipation, along with the cost of a 500w 4 ohm resister worth it?

Or,should I just bore ahead and either buy a 400w-500W, 8 ohm(my amp puts out 450W to 2 8ohms or 1, 4 ohm) speaker and replace the 4 ohm speaker in the Peavey cabinet or, just find another 8 ohm cabinet on ebay/craigslist?

Just trying to do the most with a little.

Thanks for telling me your thoughts.

Forget about adding resistors. Search if you want explanation, it's not an uncommon crazy question.

What's wrong the 4 ohm 15 as it is?

A complete waste.....

Whatever reduced wattage output you will get at 8 ohms will now be cut in half again it will be split evenly between the speaker and the resistor/space heater.

If you really want to keep it, someone around here compiled a pretty decent list of 2Ω capable heads. search.

Perfect. Thanks. That's what I thought.

Downunderwonder - there's absolutely nothing wrong with it. I rather like it. It's just that I'm trying to put together a stacked rig where my 450 w goes to two 8 ohm cabinets. I already have the 4x10 8 ohm cab and I need a 1x15 8ohm cab to pair it with.

Ok, looks like I'm shopping for a 15" 8 ohm speaker.

Thanks for all your insight.

That is a bad combo of cabs for a number of reasons.

If you have to "shop", might as well be for a match to the 4X10 you already have.

ya might as well get another 8 ohm 410, or get an 8 ohm 115 cab and find an 8 ohm driver for your current cab (if that driver has an 8 ohm version). either way, i'm confident that the advice on here regarding 410/115 is solid. it's just a gamble. it might work well for a given room, but there's just as much chance that it won't work well for any room.

also consider the 2:1 "rule" with bass cabs. depending on how you eq, you should keep the "power" rating on the cabs 2x (+/- a little) the power your amp is rated for. for example, with an amp that has a rating of 450 watts, a pair of cabs (with the same #of speakers, the same impedance) should add up to about 900 "watts". although in the real world, you could still expose these cabs' physical limitations with a 200 watt amp and a badly smiley-faced eq.

It is not worth pairing a 15 with a 4x10. It will always be a weak link and subject to being blown. If you want a second cabinet, add an identical one to what you have. that way there are less chances of an undesirable pairing.

First, the resistor would be huge - it would have to handle at least half your power. and it would get HOT - how would you mount it and shield it??
Second - that half of your power would go up in heat - what a waste!

Just -
Buy a new cab or
Replace the driver with an 8 Ohm version.

No, you don't. :) As the other guys said, you need another 4x10. You'll get far more low end strength that way, than by adding a 1x15.

The OP didn't ask about mixing cabs, only changing the impedance of an enclosure. I would stay away from the resistor method. If the Peavey is a Black Widow or Scorpion, you can simply buy the correct replacement basket in 8 ohms and use the existing magnet. If not, just purchase an 8 ohm speaker appropriate to the tuning of the enclosure......or get a fearful :ninja:

Yeah. That means he got some great free advice - without even having to ask for it. :hmm:

Ain't TalkBass grand? :smug:

MM

"resistor method" implies some validity to that crazy scheme, there is none.