# Another Hare-brained scheme



## NGroeneveld (Jan 23, 2011)

Okay, dumb question alert. I got this Fender Champ 600 head that needed some sorting out, which was successful, and I hooked it up to two 10 inch Fender Special design 8 ohm speakers. Sounds great. I needed two speakers because the amp is only rated at 4 ohms, and I only had 8 ohm speakers available. You get that right? Great. But one of those speakers came out of another amp and I want to put it back in there. That leaves me with only one available 8 ohm speaker which is the wrong load for the amp. 

Now I do have a crummy six inch 8 ohm speaker that I think came out of a really cheap cassette deck. It's not good enough for a guitar amp - not for decent tone anyway. 

Insert dumb question here - what if I take the cone out of the cheap speaker? Just cut it out. Attach it anywhere inside the cabinet wired with the other speaker. The cheap speaker will not be making any noise, right? The other speaker will work like normal. Then I should have the proper load, and I can avoid having to spend any dough on a 4 ohm speaker.

Thought I would ask before destroying a perfectly good (crappy) speaker!

Will it work?

Thanks!!!


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## Hammerhands (Dec 19, 2016)

How about an 8 ohm resistor?

You will get less volume either way. They use a speaker motor in some of those load boxes. It still vibrates, so you may have to isolate it.

I would find a 4 ohm speaker, they are not expensive.


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## nonreverb (Sep 19, 2006)

I agree with Hammerhands. There are a few reasons why this probably won't work. The major one being, if you remove the cone from the speaker, you change the damping that's usually applied to the voice coil. Now you have a spider and a coil. I suspect it will sound like you have a bee stuck in the back of your amp, partly because the suspension has been changed and also because even at 6 watts, you'd probably be driving that speaker past excursion in it's modified condition. The static resistor is the best option until you're ready to spring for a new speaker.


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## NGroeneveld (Jan 23, 2011)

Great! - thanks guys


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## jb welder (Sep 14, 2010)

Also, the speaker magnet acts as a heatsink for the speaker coil. The coil on it's own will burn up fairly easily. Maybe not in such a low power amp as a Champ, but something to keep in mind.


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## mhammer (Nov 30, 2007)

I don't know that simply using a single 8-ohm speaker is necessarily *bad* for that amp. Certainly going the _other_ way (from 4 down to 2) might jeopardize the output transformer, but 8 would noit, or should not compromise the lifespan of the amp. It might probably alter the tone, but it won't draw as much current.

But I will defer to those who know more about the alchemy of tube amps.


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## nonreverb (Sep 19, 2006)

mhammer said:


> I don't know that simply using a single 8-ohm speaker is necessarily *bad* for that amp. Certainly going the _other_ way (from 4 down to 2) might jeopardize the output transformer, but 8 would noit, or should not compromise the lifespan of the amp. It might probably alter the tone, but it won't draw as much current.
> 
> But I will defer to those who know more about the alchemy of tube amps.


That's actually not so. Going up in impedance with a tube amp is always worse for the transformer. Remember, most fender amps have a shorting speaker jack. Why? Even if the transformer secondary is shorted the internal impedance of the primary is still there (it's off spec mind you). If the secondary is dead short, it cannot transfer any power P=(I squared) R. If there's no R, there's no power transfer. The available current is there but the voltage swings are very low. That's why when you place a lower impedance speaker...say a 4 ohm on an 8 ohm tap, the sound suffers...less bass...less power.
Going in the other direction is where things fry. The extreme case is the open condition. An open gives the signal no where to go so it gets reflected back into the transformer (flyback voltage). In extreme cases, this can be in the 1000's of volts. It can take out an output transformer in short order as the high voltage will punch a hole through the laminations and/or insulation. Most output transformers can take a 100% mismatch increase from spec...but not all and connecting a 16 ohm speaker to a 4 ohm tap and cranking it is simply asking for trouble.


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