BillFitzmaurice.info

Hello.

I'm wanting to rewire my tubas to series due to an amp change. I currently have 2 x 4ohm tubas wired in parallel, but I want them in series to go to 8ohm. The amp only goes down to 4ohm per channel.

I want to use the second speakon out as a link to daisy chain to the other cab.

Any helpful diagrams on how to rewire the speakon connectors on both cabs would be a great help?

Or maybe I can leave the wiring on the cabs and make up a link cable? Or maybe not.
I don't think I've missed anything. But maybe I have.

Thanks

What is your driver configuration that makes them 4 ohms?

Each cab has 1x 4ohm BP102 driver and I have 2 cabs

There's a couple ways to achieve your goal. This is probably the most reliable and non confusing way to do it.

Leave your subs wired the way they are and create a pigtail that externally wires them in series. With this arrangement you wont have to remember which sub is which. Just plug the pigtail into them, in any order, and they'll work as intended. If you wanted to do it internally, you'll have to keep track of which sub is wired which way and always hook them up in order... the series wired sub first and the normal wired sub second. And the series wired sub will not work unless the normal wired sub is also attached. So, if you do a gig that only requires a single, you have to make sure you bring the one that's not wired for series.

I take it the other channel of the amp is in use?

I would do a breakout box, rather than a pigtail. Seth's example is much prettier, see my version attached. The side with one plug is connected to the speakon from the amp. The side with two speakons has a standard speaker cable to each cab, using cabs wired in the standard fashion.

These are the T24's you asked about upgrading to KL3010LF's before?

If yes, I reread that thread.
4 ohms BP102's do not have the same voltage limit as the standard 8 ohm BP102.
The 4 ohm BP102 limit is lower. I want to say it's 27V, but that might not be right.
Hopefully Bill will chime in in that regard.
If it is right, then you need to limit the cabs to 54V...

Grant Bunter wrote: ↑Wed Oct 07, 2020 4:29 pm I would do a breakout box, rather than a pigtail...

Ooh, I like that option too!

SethRocksYou wrote: ↑Wed Oct 07, 2020 6:30 pm

Grant Bunter wrote: ↑Wed Oct 07, 2020 4:29 pm I would do a breakout box, rather than a pigtail...

Ooh, I like that option too!

I should have explained it more I guess.
On the side with one speakon, +1 goes to +1 on the left of the 2 speakons side.
1- from that speakon goes to 1+ on the speakon on the right.
And 1- from that second speakon goes back to 1- of the single side speakon…

Excellent. Thanks for the replies.

I'll make a pigtail first to get up and running but I love the idea of the breakout box as it will be much more robust.

I also need to learn more about this Voltage limiting. ATM I'm just brick wall limiting on my ultradrive at the -25dB threshold.

If you can point me in a direction for this that would be great.

I'm glad I don't have to rewire the subs.


Thanks again

I should have said earlier, but a lower voltage limit with the 4 ohm BP 102 doesn’t mean less output. The output is the same, but voltage limit is lower because impedance is lower.

Voltage displacement limiting is the full name, and it’s mandatory in horn loaded cabs as they just stop working, as mentioned in your other thread. It’s all about protecting not just your drivers, but also your investment. The voltage limits are determined by Bill, using modelling and TS parameters.

The DCX 2496 is more than adequate as a brick wall limiter (and parametric EQ), it’s only downfall (other than a quirky manual and sudden weird shit happening that requires lifting the lid and reseating all the connectors) is you also need to pair it with a DEQ2496 for graphic EQ and RTA. I have 2 of each in different racks, but banging them about in the back of a truck in outback Australia has lead to me getting and using a DBX Driverack PA2 for the same functionality at less cost and 1RU of space.

To set the limiter properly (not the dynamic limiter by the way), run a 60Hz sine wave to unity gain, and master outputs to 0 on the meters. Feed that output to the DCX. On the sub output for these cabs eg output 1, scroll through the pages. Set the high pass at 45Hz with 2 cabs, and the slope to LR48, then low pass to 100Hz, and maybe a slope of BW12 or 24 (try each later).
Connect the amp, attenuators full on, with no cabs attached, to eg output 1. Scroll to the limiter page, restore the limiter to 0, and measure the output on the amp channel for the subs with a multimeter set to 200v AC. If the amps output voltage is greater, in this case, than 54V, dial in the limiter until it reads 54V.
Finally, slam your master fader and/or channel strip faders to max. The 54V shouldn’t change, but, if it does, adjust the limiter some more.
Hook up the cabs and you’re done, and no one can blow your drivers.

The same can be done with any and all types of cabs BTW...

That's great. Thanks for that.

I'll walk through it with my system today.

The Pigtail works but the box version will be much prettier to look at(even tho I used the box version as a wiring diagram )


Thanks again.