Bridged Mode cabling

mclir9

I am Bridge Mode from a 4000W AMP to a pair of Yamaha SW118V's. I have re-configured the Speak-On cable from the AMP to the first Yamaha as +1, +2... my question is do I need to setup the speakon cable paralleling to the other speaker in the +1, +2 fashion also??

Gadget

Oh boy.... Well...the problem here is that at the amp end the bridged output is 1+ and 2+ but at the speaker end it's 1+ and 1-....therefore, to avoid confusion I would recommend making a patch panel that has 2 paralleled speakon jacks on it that do the conversion. Then you have 2 same length cables with 1+ and 1- that go to the speakers...

If you daisy chain the speakers the first one in the chain get MORE Power than the second...common practice is for equal cable lengths from the amp to each speaker, especially with sub woofers that require all the power you can muster...

remov1

Interesting, I recently began running a similiar setup for our 2 JBL PRX415 mains using a 25 ft cable with one 1+ 2+ end connected to a 2000W bridged mono amp and the other 1+ 1- end to the first speaker, then daisy chaining the second speaker using a 50 foot cable. I thought this would result in 1000W per speaker but apparently that's not the case? I didn't realize when daisy chaining using different cable lengths would be an issue. Is there a chance of causing speaker damage or is this primarily an issue of volumn balance between the two speakers? Our sound since moving to this configuration has been excellent and there doesn't appear to be any detectable difference in volumn between the two speakers.

Gadget

Oh boy... :roll: Oh, I said that already... well here is the problem.... all wire is not created equal.. the answer is "it depends" but consider this...Crown states that :

runs of 25 Ft or less work well with 14 gauge. Over 25 one should use 12 gauge if possible.

Used to be that they had a chart indicating what the resistance of a foot of wire used to be, now I presume that there are so many grades of wire that this line is no longer a definable quantity...

However, a 50 foot run of other than 12 gauge wire starts to present some issues for the amplifiers, not the least of which is amount of power that ACTUALLY gets to the speakers... if I was to tell you just how little actually hits the speaker, you'd think I was on crack...add to that an ADDITIONAL 50 feet of wire and you compound the problem .... well MANY times... Consider the current loss over a given piece of wire, consider also the back electromotive force, and the Xl/Xc of the speaker and your sending only a minor fraction of the power you have at the amps to the speakers...

While the problems is mainly prevalent in subs due in large part to the power hungry nature of subs, it isn't negligible in tops either...

If you do your homework you will see that proper connection begins with EQUAL runs from the amps to the speakers.. and that proper gauge wire is part and parcel of proper connection if you expect to get the full potential out of your amps...

FYI ...IF, you daisy chain the speakers... and in your zeal to cover that EXTRA large crowd the just happened on the club... and you have the club owner and the tour manager screaming "TURN IT UP" you KNOW your running above your capacity...but you press on...then someone comes and starts yelling at you 'Hey man your speaker is on FIRE!" remember this little chat.. I promises I won't take ANY pleasure in telling you "I" well we'll just save the rest for later...

Dra

Electricity is a weird thing.
(Cable) size does matter.
(Cable) length does matter.
I don't understand it. For example, it is recommended to use the largest awg possible to avoid signal loss (typically 12), yet the speaker manufacturers commonly use 16 awg inside the cabinets. And the same size for the 20w tweeter as the 400w woofer. Go figure.

In such a short length, the resistance, capacitance, etc apparently don't cause a problem, even thought the current just traveled 100' from the amp. Could you reverse the wiring and put a 2' 16 awg wire section at the amp, then connect 100' of 12 awg with the same results?

I too have looked for that old db loss chart that seems to have stored in that secret government facility with the alien DNA canister.

Then there's the whole some frequencies like skin, some like core thing.

As far as your 50' daisy-chain. The 50' of added resistance is just that. Like water, the flow will go where there is least work. In this case, the shorter run. Granted, maybe only a db or 2, but depending on the volumes that you are dealing with, that could be a difference of 50w or 500w between the speakers.

DRA

PS - Here is a simple test. Take a 10' speaker lead with a 1/4" plug on end and one with 100'. With a sine signal from the amp, alternate the 1/4' plugs into your mouth and compare the difference. :shock:

OklaPony

Is this the type of speaker wire calculator of which you speak?

http://www.bcae1.com/images/swfs/speake ... istant.swf

I haven't messed with bridging in many years. At the time the system I was using was banana plugged directly into the amps so I ran equal length cable to each 8 ohm cab with the banana plugs stacked one behind the other on the red terminals, positive to channel one. The cabs were terminated in jumbo 1/4's then wired straight to the corresponding speaker terminals on the speaker. I was advised to do it this way by someone I trusted... it seemed to work fine and nothing blew up (thankfully).

Dra

The one I remember was just a spreadsheet style charting. I recall the db loss being more sustancial than shown on this link. It has been 8 or 10 years though.
:?
DAR