Connecting Speakers to Power Amp

[David Carter]

I'm on the verge of finishing my second DR250, and when it done, I am going to connect the pair to a borrowed powered mixer to test them. I've never had multiple cabs before, so I want to make sure the way I'm planning to connect them to the amp is correct. I built the DR250's with 2 speakon jacks in each, so I'm just wanting to confirm that the way to connect both cabs to a single side on the amp is to run one cable from the output to the first cab and then another cable from the other jack on the first cab into the second cab.

Is that correct?

[SoundInMotionDJ]

Yes, that is correct.

[DaveK]

Assuming you wired the Speakons in parallel, this is correct. Parallel meaning that their +1 posts are jumpered together and their -1 posts are also jumpered together.

[David Carter]

Assuming you wired the Speakons in parallel, this is correct. Parallel meaning that their +1 posts are jumpered together and their -1 posts are also jumpered together.

That's what I did. Thanks to both of you.

[LelandCrooks]

I'm on the verge of finishing my second DR250,

Man have you come a long way since starting here. Congrats

[David Carter]

I'm on the verge of finishing my second DR250,

Man have you come a long way since starting here. Congrats

Thanks! It has been a great learning experience and lots of fun. And, of course, I never could have done it without all of you here helping me out. Bill's plans are very good, but there is also and indispensible wealth of knowledge and practical advise that you guys have to offer which makes it a lot less scary for newbies like myself.

By tomorrow, I should have in my arsenal 1 Omni 10 (for bass rig) and 2 DR250's for PA. After that. I'm going to need to take a break for a while. But I hope, at some point, to be able to sell my Omni 10, move the DR250's to the bass rig, and do a 2xDR200 and 2xTitan39 small rig for PA.

[Tim A]

Dave: I'm compelled to make a comment here. Remember than longer cable = more loss. When I daisy chain cabinets (which is the method you're referring to), I use the shortest possible cable between the two cabs. Here's a table from Yorkville's website. I'm not sure exactly how accurate it is, but it at least gives an idea of what I'm talking about:



Pick your cable gauge, hopefully at least 14, then look at the runs. As an example, If you have 2-50' cables, the first cabinet is on a 50' run while the second is on a 100' run. (50' + 50')

My preferred method is to build a simple breakout box. Basically, a $0.79 plastic electrical box with a cover and a clamp. Run a short piece of cable with your preferred connector on the end to plug into the amp. On the box cover, install two jacks for the speaker cables, wired in parallel. Now you can plug the box into the amp, and the cabinets each have an equal run. Basically, this is a glorified 'wye' cable, but it works very well.

Depending on your cable gauge and lengths, this may or may not be an issue. Some people don't care, but it bugs me so I address it in this manner.

[David Carter]

Dave: I'm compelled to make a comment here. Remember than longer cable = more loss.

Thanks, Tim. I was aware of the issue, but it's nice to see the data. I also like your homemade breakout box solution. My immediate need was just to be able to hook them both up correctly to test them and make sure they're both working properly. When I actually take them out to use them with the band, I will be much more thoughtful about how I hook everything up.

Thanks again for the great tips!

[SoundInMotionDJ]

My preferred method is to build a simple breakout box. Basically, a $0.79 plastic electrical box with a cover and a clamp. Run a short piece of cable with your preferred connector on the end to plug into the amp. On the box cover, install two jacks for the speaker cables, wired in parallel. Now you can plug the box into the amp, and the cabinets each have an equal run. Basically, this is a glorified 'wye' cable, but it works very well.

Ooooo...I like it. I like it a lot.

I'd make mine up with four jacks...plug into the single speakon on the amp, and run up to four speakers from that breakout box - and that's my min load anyway.

OR...I could make up just the box with five jacks. Then you run one really heavy gauge speaker wire from the amp to the box, and plug into the "input." Then you use short wires to connect the speakers to that breakout box.

--Stan Graves

[Tim A]

In my case, I make a single run to each side of the stage. Any daisy chaining between cabs is with a 2 foot cable, so the amount of loss is so small it's not even worth discussing. The main concern is the 50 run with another 50 run on top of it.

If'n I can remember I'll take a picture of one tonight and post it in here.

[Bill Fitzmaurice]

Those Yorkville charts aren't accurate, as they don't consider impedance. Use this calculator instead:
http://www.stealth316.com/2-wire-resistance.htm
For maximum performance you want the wire resistance to be 1% or less of the load impedance, though as much as 5% is acceptable. With the cost of copper being what it is you can see that a 100 foot run to a 2 ohm load is a really bad idea, and that's why amps are on the stage, not in the FOH.

[Tim A]

Yorkville's does show 4 and 2 ohm loads, I just didn't post it to get the point across. That resistance calculator is excellent, I keep it saved in my bookmarks.

That brings up a question. In the case of daisy chaining 2-8ohm loads, the amp would see 4 ohms. Let's say we have 50' cables. The cable from the amp to cab 1 would be carrying 4 ohms, while the cable from cab 1 to cab 2 would be carrying 8 ohms. How would you calculate that? Would you just use 4 ohms and call it good, or would you calculate 4 ohms for the first 50' run, 8 ohms for the second, and add the two together to get loss for the second cab?

[Bill Fitzmaurice]

Yorkville's does show 4 and 2 ohm loads, I just didn't post it to get the point across. That resistance calculator is excellent, I keep it saved in my bookmarks.

That brings up a question. In the case of daisy chaining 2-8ohm loads, the amp would see 4 ohms. Let's say we have 50' cables. The cable from the amp to cab 1 would be carrying 4 ohms, while the cable from cab 1 to cab 2 would be carrying 8 ohms. How would you calculate that? Would you just use 4 ohms and call it good, or would you calculate 4 ohms for the first 50' run, 8 ohms for the second, and add the two together to get loss for the second cab?

Calculate the cable to the first cab based on a 4 ohm load, 50 feet, the cable to the second for 8 ohms but for 100 feet of wire back to the amp. You'll see that using more than 50 feet is not a good idea, better to have the amps placed so that there is no run longer than 50 feet.

[gdougherty]

If I recall my calcs correctly, for a 2-4ohm load at 50ft to be in that ideal range you need at least 10ga cable. A friend of mine picked up 100ft of 12/4 at a garage sale and gave it to me, so I'm running that as 2 pairs of 9ga to the speakers and then 2ft jumpers made from Carol 14/2 I picked up at Home Depot to go speaker to speaker. The extension box sounds nice, but what's the point when you have parallel jacks on the speakers? The extra 2ft going speaker to speaker doesn't add enough resistance to worry about. If you really wanted you could make the jumpers up out of 12/2 instead, but 14/2 is all I could find in a black rubber jacket in bulk locally.

[Tim A]

Finally remembered the pic. This one was made up to go from 1 Speakon to 2 1/4". I'm weding out 1/4" stuff as I go, so this will eventually get changed over to all Speakon.