Bridging a stereo guitar amplifier

[Saddlebacks]

can anyone give me a link to a site that explains *how* to bridge a stereo guitar amplifier?


I have a fender ultimate chorus 2x12 combo, that runs 2, 65 watt 8 ohm channels in stereo. I want to create a single mono channel that has 8 ohms.
I understand that series-bridging this amplifier will produce 260 watts, with 8 ohms, yet I cant find any site that explains how to go about doing it.

[Farview]

The amp must be designed to do it. If it doesn't have a switch, you can't do it.

[boingoman]

The amp is not likely to have the current handling capability to do this at 8 ohms. Bridging pretty much requires that you stay at at least double the minimum impedance load for one channel, if not more than double. Bridging that amp into an 8 ohm load will get you a fire.

Many PA power amps can only be bridged into 8 ohms, for instance, even though they can handle 2 ohm loads.

Without knowing the exact current handling capability of this amp, it is a dangerous proposition. Seeing as it is a guitar amp, it likely has barely enough nuts to run the way it is now, much less bridged into anything less than at least 16 ohms.

If the amp does not have stereo inputs, it's gonna be really tricky in any case, requiring a rework of a lot of stuff in the amp.

Bridging a stereo amp is a technique to put the full power of a stereo amp into a single load. It does not double the amp's output power.

[Saddlebacks]

gahhh!


well if it cant be bridged, maybe someone could help me with my main problem..


im trying to convert this combo into a half stack

i have four 8 ohm speakers, that i want to connect to two 8 ohm channels?

how do i go about accomplishing that?


the only way that ive heard of would be to wire the speakers so that they are 16 ohms, but this makes me loose half of my total wattage, and im trying to get a bigger sound, not smaller



this is the link that gave me the idea about the bridged amp technique, i figured that the SAE p50 was a guitar amp

http://www.audiocourses.com/article81.html

[boingoman]

The theory is solid, and he explains the problems, but doesn't really caution people against doing it, which is a little odd. He also doesn't mention you can blow an amp doing this incorrectly.

Oh, I see. Yes, he is explaining things to owners of amps that have a bridge mode built in.

I'm stuck on a solution for you, beyond selling the 8 ohmers, getting 4 16ohmers, and running a 4 speaker box in stereo, both sides at 8 ohms.

[Farview]

Originally Posted by Saddlebacks

gahhh!


well if it cant be bridged, maybe someone could help me with my main problem..


im trying to convert this combo into a half stack

i have four 8 ohm speakers, that i want to connect to two 8 ohm channels?

how do i go about accomplishing that?


the only way that ive heard of would be to wire the speakers so that they are 16 ohms, but this makes me loose half of my total wattage, and im trying to get a bigger sound, not smaller



this is the link that gave me the idea about the bridged amp technique, i figured that the SAE p50 was a guitar amp

http://www.audiocourses.com/article81.html

If you are coming from a 2 speaker combo and going for a 4 x 12 sealed cabinet, running each side at 16 ohms will be fine. You will loose half the wattage (-3db per side) but gain the extra speaker (+3db per side). Add to that, the fact that all 4 speakers are in the same cabinet... You might be getting somewhere.
You could also buy 4 more 8 ohm speakers and have two 8ohm 4 x 12 cabs
and really empress the ladies.

[Saddlebacks]

do they sell specific ohm rated resistors?

like, an 8 ohm resisitor, that would act as a fake speaker?

for no purpose other than adding resistance to a circuit






and... where would one trade in speakers at?

[Saddlebacks]

i took a picture of the back side of my amp,

each speaker is attatched to its own pair of wires, run from its own power amp

what effect would it have if i attatched the black wire to the black wire, and the white to the white respectivley, and then attatched the paired white and paired black to a female 1/4inch plug, (like on the back of amp heads), and then connected that plug to my speakers, would that create a mono 130 watt 8 ohm channel? (most likely just high hopes on my part)


?

[mshilarious]

Originally Posted by Saddlebacks

do they sell specific ohm rated resistors?

like, an 8 ohm resisitor, that would act as a fake speaker?

for no purpose other than adding resistance to a circuit

Yes. But why? They'd just take the same amount of power as a speaker of the same impedance without the corresponding increase in volume. They would make your amp quieter, not louder.

[Farview]

Originally Posted by Saddlebacks

i took a picture of the back side of my amp,

each speaker is attatched to its own pair of wires, run from its own power amp

what effect would it have if i attatched the black wire to the black wire, and the white to the white respectivley, and then attatched the paired white and paired black to a female 1/4inch plug, (like on the back of amp heads), and then connected that plug to my speakers, would that create a mono 130 watt 8 ohm channel? (most likely just high hopes on my part)


?

That is not how you bridge an amp. In a bridged amp, one side of the amp takes the positive swing and the other side takes the negative. the speaker attaches to the 2 positive leads. If you do what you propose, you will blow your amp up. Don't do it.

BTW what are those jacks in the upper right of the picture for?

[Saddlebacks]

those jacks are footswitch, and mono/stereo fx loops



but thanks for the response