AMP BRIDGING HELP!!

Hello FSP ppl,

new to this forum and PA in general, so forgive me if i am being a dumb f***

we have 4 x double W bins each loaded with 2x 600w 8ohm eminance (i think) drivers so each cab total in at 1.2kw each, we currentlly use theese for the lows. we also have 2x 500w full ranges 8ohm + 2x 400w 4ohm full ranges wich we use as mid high. i am in the process of buying/building 4 x 1850 horns wich i am going to load with pd1850,

when powering theese i understand (heres where i may be a dum f***) bridging an amp takes away one channell meaning all the power goes to one channell, with just one input and no outputs on each of my bins this means i can not daisy chain my subs, does this mean a different amp will be required for each invidual sub/kick bin? so 8 amps in total for the lows and kicks? i know my mid tops have 'input' and 'output's so i can daisy chain theeese i just dont understand how the kicks/sub bass will work???

cheers in advance for your help people!


Ben

Bridging an amp basically connects both channels together so they are both putting power into the same load.

Check the manual for the amp to ensure that it can be bridged and if so, the power output available at different loads.

Normally it is easy to work out. If the amp can give 2x 1000w at 2 ohms, then it will normally be rated at 1x 2000w at 4 ohms.
Note that the minimum impedance in bridge mode is higher than in normal stereo mode!! - Don't blow up your amp by connecting a load that has too low of an impedance!

So now you know what your amp can do. You can still link cabs so that the amp drives more than one, but ONLY if the total load is safe for the amp.

EG: Your amp can be used at 4 ohms in bridge mode. You have 2 cabs which are 8 ohms each. If you chain them together (in normal parallel mode) you get a load of 4 ohms.... this is fine.
If your cabs are 4 ohms each then chaining them in the same way gets you a load of 2 ohms which is too low and you can't use that amp.

Make sense?

Cheers,
John

I just had a think about your speakers:

The kicks (W-bins with 2x 8 ohm 600w drivers) are probably best powered by amps running in stereo.
Each cab is 1.2kw and 4 ohms. It is easy to find amps that provide about 1.5kw per channel at 4 ohms.
You will need 2 amps for kicks.

The "sub" (1850s with 8 ohm drivers, 800-1000w) are best powered by EITHER:
One BIG amp (Proline 3000 is the obvious choice here!!)
Two smaller amps, bridged into 4 ohms load and able to supply about 2500w+ at 4 ohms.
The price for both options should be about the same.

I would recommend two smaller amps for the 1850s as this means if something goes wrong with one you still have one. If you get an issue with the big amp then it's all gone. Big amps can be troublesome with poor power supplies and generators too.

Let me know if you need anything explaining in more detail.

Cheers,
John

I have 4 w bins, so if im running a bin off ov each channell on both amps how do i connect amps together? as bridgeing takes away a channell meaning i would need 4 amps, 1 per bin as my w bins do not have speacon links in the back do daisy chaining is not viable.

Any suggestions for the 2 amps to power the 4 subs?

cheers for the help mate

add speakond to each cab so you can daisy chain them, very very easy to do, all you will need as a drill, drill bit, speakon sockets a bit of wire, and some solder........ im sure we can talk you through how its done, this way you could get away with 2 amps.......

in the back of my bins i have the 2 cables with clips on the end coming from the driver to the double speacon socket, each speacon has 4 pins at the back, the 4 crockodile clips are from the 2 drivers are on theese 4, so the other speakon socket is not being used, how do i wire it up to allow me to daisy chain subs?

cheers all

bee wrote: add speakond to each cab so you can daisy chain them, very very easy to do, all you will need as a drill, drill bit, speakon sockets a bit of wire, and some solder........ im sure we can talk you through how its done, this way you could get away with 2 amps.......

dont daisy chain them in bridged as they sound like the w bin are wired up 4ohm

i would series wire the drivers in each cab so they would be 16ohm, then daisy chain 2 cabs to a amp bridged into 8ohm!

16ohm+16ohm=8ohm

then the same with the other 2 cabs

smiley20

link the same wires to the other speakon, so +1 joins to +1 on the other speakon, -1 and -1 are linked etc simple as that....... see pic below this list common speakon sockets.....

it may be worth while to re wire each cab to 16ohms that way they would be a 8ohm load when linked..... so you would need an amp that can do 2500 at 8ohms......

Regarding the suggestion to re-configure the W-bins to 16 ohms:
I don't see this as a viable solution.

You will need a SERIOUS AMP that can supply 3k at 8 ohms!

Like I said above the most efficient way to configure the 4 cabs (8 drivers) is to keep them configured at 4 ohms and use ONE AMP CHANNEL for each cab. That's 4 channels = 2 amps (or a single 4-channel amp - but it will need to be something like a Void QX6 for the power).

You wont need to modify the cabs either as there is no need for linking.

As for daisy-chaining, here's how it works:

In the back of the speaker cab you fit two Speakon connectors. These have 4 terminals on the back.
Connect each terminal to the matching terminal on the other connector. So 1+ connects to 1+.
Then take the 2 cables from the speaker/s in the cab and connect them to the 1+ and 1- terminals (on either socket as they are both joined anyway).

It's often easier to cut the link between the two sockets and solder the three cables (speaker and 2 connectors) together than it is to attach two cables to a single terminal on the Speakon. Remember to securely insulate the join with heat-shrink or quality electrical tape.

For cabs with 2 speakers, it is easiest to run 2 cables to the first driver and then another 2 cables from that driver to the 2nd. Otherwise you end up with loads of cables at the Speakons that are a bit tricky to connect together.

Finally, there is one other solution:
Rather than modifying the cabs, you can easily make up a Speakon splitter/loom.
Simply get a small plastic box (Maplin £5 each), fit a Speakon socket (this is where you plug the cable from the amp in).
You can either fit two more sockets (one for linking to each speaker cab), or two 1m+ lengths of speaker cable with a Speakon on the end to plug into the cabs. This is a quick and easy solution.

To set up: take the thing you just made and connect it to both cabs. Connect your amp to the "input" socket on the box. Job done.

Let me know if you are still unsure when I drop the 1850s off and I'll go through it with you in detail.

Cheers,
John