Accidently Plugged Speakon Cables In Wrong

[mam1862]

Last night while setting up, I accidently plugged the speakon cables from the amp into one cabinet instead of two. We were short two guys and I was setting up the pa and checking the sound for everything. I didn't even notice it till the end of the night while tearing down. It sounded good all night. I have to check to see if anything even happened. My question is what is the potential damage in doing this? I was using a GK MB Fusion and a MB NY604. I wasn't pushing it too hard as we had the pa support. The gain was at 12:00 and the master was at 9:00.

 

[Morning Beer]

If I think I get what your saying. It isn't a problem running one cab. Your amp would just wouldn't be running at a 4ohm load resulting in less watts.

(edit) If you connected 2 wires to the same cab from the head I would be nervous. If thats what you did I would think the fusion would go into protect mode or the cab/head would have been smoked

 

[bongomania]

Wow, interesting... I don't really know what would happen. My first guess is that the amp would see the load twice, so if the cab is 8 ohms then the amp would put out the wattage as though it saw 4 ohms. The signals, being nearly perfectly in phase, would increase in amplitude that way as well. So you would have been sending a much stronger signal into the one cab, which might have sounded similar enough in volume to the two-cab setup not to notice. Of course this puts double the strain on the one cab, putting it at risk of failure sooner.

Again though, I'm just guessing here.

 

[INTP]

sounds like bi-wiring to me, which would have essentially no effect. If it had actually been miswired, I think you'd have known.

 

[mam1862]

Wow, interesting... I don't really know what would happen. My first guess is that the amp would see the load twice, so if the cab is 8 ohms then the amp would put out the wattage as though it saw 4 ohms. The signals, being nearly perfectly in phase, would increase in amplitude that way as well. So you would have been sending a much stronger signal into the one cab, which might have sounded similar enough in volume to the two-cab setup not to notice. Of course this puts double the strain on the one cab, putting it at risk of failure sooner.

Again though, I'm just guessing here.

That's what I am thinking or worried about as the cab is rated at 8 ohms.

 

[Zooberwerx]

sounds like bi-wiring to me, which would have essentially no effect. If it had actually been miswired, I think you'd have known.

That's what I'm thinking. Keep in mind that a conventional bass head's speaker outputs are wired in a parallel config....the "+" on speaker output A is connected directly to the "+" on output B.

Riis

 

[Andyman001]

If speaker inputs are parallel and amp outputs are parallel, then its just like using a bigger speaker cable no harm done.

 

[Downunderwonder]

Good thing you weren't playing loud. If I read it right one cab did all the work while the other did nothing. No harm done.

 

[MAMMOTHvolume]

That's what I'm thinking. Keep in mind that a conventional bass head's speaker outputs are wired in a parallel config....the "+" on speaker output A is connected directly to the "+" on output B.

Riis

This. Unless it's a Stereo amp in which case paralleling up the outputs isn't the greatest thing ever to do.

 

[Handyman]

If speaker inputs are parallel and amp outputs are parallel, then its just like using a bigger speaker cable no harm done.

+1

What occurred was 100% harmless.

 

[vin*tone]

The moral of the story is.... next time leave the other cab at home. You don't need it.

 

[chadds]

The moral of the story is.... next time leave the other cab at home. You don't need it.

LOL!!!!

 

[BullFrogJR]

Ok, I'm a bit confused about this. The basic consensus in this thread is that it's ok to plug both parallel outputs of a single head into two parallel inputs on the back of a single cabinet. But I don't understand why?

There are several other threads on TalkBass addressing the question of plugging two heads into a single cabinet. Now, I understand that you would never want to have both heads powered up and sending a signal to a single cabinet. But, some of the threads deal with having both heads plugged into the same cabinet and only use one head at a time (perhaps for a quick backup). This actually sounded like a good idea to me. But, the general consensus is that you absolutely can NOT do this because the signal from one head will enter the cabinet, leave it through the other connection and enter the second head. Which is bad

So, how is the situation in this thread any different? Won't the amp want to send its signal from the cabinet back to the second output on the back of the amp?

Forgive my ignorance, I'm new to this kind of stuff, but I very much would like to understand why it's safe to plug both outputs of a head into one speaker, but not safe to have two heads connected to one speaker even if only one head is being used at a time.

 

[mam1862]

Thanks for the input everyone. Good stuff.

 

[Steve]

So, how is the situation in this thread any different? Won't the amp want to send its signal from the cabinet back to the second output on the back of the amp?

That scenario as presented is a mono amp with parallel outputs into one cabinet with parallel inputs.

When things are parallel they are electrically speaking, "as one".

So, you have two start points electrically as one traveling on two cables electrically as one, going to two end points electrically as one.

The scenario of two amps going into one parallel input is as two going into one. Two separate amps into one input or right and left side of a stereo power amp into one input..not good at all.

 

[skychief]

Ok, I'm a bit confused about this. The basic consensus in this thread is that it's ok to plug both parallel outputs of a single head into two parallel inputs on the back of a single cabinet..

Ummm i think ya got it bass akwards...

Here is OP's 1st sentence:

"Last night while setting up, I accidently plugged the speakon cables from the amp into one cabinet instead of two."

ONE amp

TWO cabs.

So, he ran all nite on 1 cab. Which was not an issue since he had FOH support.

Everyone is making this so incredibly complicated.

 

[BullFrogJR]

@steve: thanks for the clarification, I think I get it. But still not totally sure.

@skychief: ok, now I'm quite confused. Maybe I did mis-understand. If he just plugged one output of his head into 1 cabinet, sure no problem. But my reading is that he "meant" to plug his head into two cabinets but accidentally plugged BOTH outputs of his head into the same cabinet. Is that not what he did?

 

[Downunderwonder]

The only questionmark is whether the head has two amps in it or one.

Two amps can run parallel into the same load only if the amps are identical, receiving identical signal input, and a whole lot more electrickery to ensure they don't end up driving each other instead of the cab, thereby letting out all the magic smoke.

Since the magic smoke stayed inside it must be a single channel amp.

 

[skychief]

Oh gosh, now IM confused! Truth is, I haven't a clue what he actually did. He used the word "cables" implying that more than one cable was connected to the cab.

As previously pointed out, since all the speakon connections are parallel, this would not effect the amp or cab in any way. It merely provided an addition path for the current to follow.

Now, if one of those speakon cables had reversed polarity...

well.....


the smoke & light show will be (briefly) enjoyed by all in attendance.

 

[mam1862]

Ummm i think ya got it bass akwards...

Here is OP's 1st sentence:

"Last night while setting up, I accidently plugged the speakon cables from the amp into one cabinet instead of two."

ONE amp

TWO cabs.

So, he ran all nite on 1 cab. Which was not an issue since he had FOH support.

Everyone is making this so incredibly complicated.

To clear up, I plugged the two speakon cables from the amp into one cab.