On our PA, it is the setting used if you're just running one speaker. It sends right and left to the same cab.

Ok, how long have you got?

Unless you are absolutely sure what it does then don't do it. You can easily lose both your amp and the speakers.

A stereo amp is just 2 amps in the same box and in stereo mode each amp has a pos and a neg side which connect to the speakers. Bridge mode takes the pos side of each amp only and connects across one speaker, in mono, effectively 'bridging' the two amplifiers hence the name.

The result is increased power.

Now this is the dangerous bit. An amplifier's power is product of its working voltage (volts) and its electrical current (amps). ie Volts x amps = Watts. This is called OHM's Law and is the basis of all electrical calculations.

Bridging doubles both the output voltage and the output current giving a fourfold increase, Threefold, lol.

Now amplifiers are stupid beasts. If you tell one to give you say 1000 watts it will try to regardless of whether it is designed to do it or not. So asking one to give you 4 times its normal power is a bit much. You will notice that the bridge rating is only double the stereo power and there is an important proviso that the speaker load is 8 ohm minimum. Connecting a 4 ohm load will normally blow it.

The main use for bridging is to drive a single mono bass bin which requires the higher wattage. It should never be used simply to try to get more power from the PA.

If there is a bridge switch my advice is to put some gaffa over it. Switching it accidentally with 2 speakers connected will damage it.

Col

Oooh the search for clean live sound. is there some secret formula ?

Bin 'googling all after noon (so much data to absorb).

Finding the Holy grail or a Unicorns horn would be easier.
Recommended rig for a 4pce rock band driving vocals/drums through 2xBass subs, 2x tops anyone?

If you link your tops to the bins the amp sees them as one 4 ohm speaker so you will pull the full rated wattage from the amp. A 1500 watt amp will be ok but then you will need limiters to prevent distortion and have to make sure the amp is never turned up past threequarters to hold the rms wattage down at 1200w. That's getting quite a bit involved and is probably not a viable option for a gigging band. It's an installation thing.

Your 1200 watt amp is the limit for your speakers power wise.

There is, however, another aspect with speakers. They have a rating called SPL, Sound Pressure Level. Not all manufacturers give you this info though. The higher the number the more air you move per watt. A speaker with a SPL of 100dB will be louder than one with 95dB at the same amp settings. So your problem may be with the SPL of your speakers.

Your amp is a good enough piece of kit for gigging. Rather than getting a bigger amp and risking the speakers blowing I would put my money into a better pair of tops around 300 - 400 watts. You'd expect to pay £300 - £500 for them but you would maintain clarity at higher volumes. Keep the bins for now and see how they sound. You may be surprised.

btw..if your speaker system were 8 ohms you'd get 72% of the rated wattage, around 720 watts, not half as most people think. Now that really is getting too deep and I'm just showing off now.

Col

I'm confused now. Where is the signal to the powered bass bin coming from?
Is the 'usual' subwoofer one of the Class D speakers. Where is the feed to this coming from?
Are you linking a bin to a top and then this pair to another top? 3 speakers like this will increase power but it reduces the speaker load to just over 2 ohms which is too low for the Soundlab. This will kill the amp slowly over a period of weeks or even months.

Can you take a photo and email or text it to me? If so send a private message for my mobile or email.

Col