hooking up the crown amp to my cube base augmentor

[vrod]

I need help hooking up my George Wright EL 84 amp to the Crown XLS1502 amp. A while ago I received some cables from ED but I must have lost the instructions. They are RCA connectors on one side and bare wire on the other, however, the RCA connectors have a positive and a negative terminal. I assume the bare end connects to the output terminal of the tube amp. I am using the CUBE. I also set the previous amp ( the APA150 ) and calibrated the inaccurate control on the back using a Radio Shack Sound Level meter and set the crossover frequency around 60Hz. I got good bass from the Cube to 35Hz with 6 decibel down at 30Hz. Below that not much is going on. My Horns are located on a corner for the left speaker and no corner for the right speaker.

[Capt. Z]

Yeap. If you have Ed's 'Magical' cable the bare wire goes at your amp speaker post out and the RCA connector into the Sub amp RCA input.

[Luddite]

Capt. Z, I agree with your instructions to vrod, except that Ed's "normal" Magic Cables used a 10K resistor per channel, but in this thread from 2013 https://tubehifi.websitetoolbox.com/post/Subwoofer-Project-6426090?&trail=135 Ed recommended using a 600 ohm resistor per channel when used with the Crown XLS series of amps.

Vrod, measure the resistance of your Magic Cable(s). If they're approximately 600 ohms you don't have to do anything except hook them up off your main amp's speaker terminals, as Capt.Z suggested. If they measure closer to 10K ohms, you may want to either change the resistors to 600 ohm, or just build yourself a new set of Magic Cables.

Oh, and one more thing. If you're going to bridge your Crown to take advantage of the 1550 watts (and you really should!) your XLS-1502 is capable of bridged, then you're going to need a Y RCA (two female to one male) adapter. The Magic Cable male RCAs will plug into the adapter, and the adapter into Channel #1 of the Crown, then select Bridged mode from the main menu.

Here's a link to the Crown XLS owners manual, if you don't have it. Refer to page #7 for connecting a single sub (your Cube) in bridged mode. https://www.crownaudio.com/en/product_documents/5055568_xlsdc2_mnl_print_050615-pdf-3c14253d-8643-4157-ba5d-cee9232d2a32
 

[thehornshoppe]

Thanks guys, just so we are clear. The original "magic cable" was only for digital amps that do not have a common ground. The 10k resistor was to isolate the grounds so the amp didn't self destruct.

 It was not like the high level cable I use for the Crown. This cable must not be used with any amp that can not tolerate a common ground, this would be most of the digital amps I have seen in the past. Things may have changed.

To make the high level cable for the Crown you need a 620-700 ohm resistor in line with the center pin of the RCA this makes the "+" and the shield is the "-" The quick and easy way is to cut a single  RCA cable in half. Strip the wire and solder the resistor to the center pin wire. Then solder a wire to it and to the shield to make the wires to attach to the amps and the RCA's go to a "Y" or to the stereo inputs if not bridging.

I hope this helps clear up a little confusion if any existed.
Ed

 

[Luddite]

The original "magic cable" was only for digital amps that do not have a common ground. The 10k resistor was to isolate the grounds so the amp didn't self destruct.
 
I hope this helps clear up a little confusion if any existed.
Ed

Thanks for the clarification, Ed. I never knew (or perhaps forgot) that the 10K resistor only applied to digital amps. I assumed (yes, yes, I know) that it had something to do with the attenuation of the signal into the subwoofer amp. So for a "normal" amp, an interconnect with no added resistance would work? If so, that's even easier.

[thehornshoppe]

Tod, NO! The high level conection MUST have a 620-700 ohm resistor in line with the hot as described above.

The "magic cable" had a 10k on the GROUND of one to isolate the chan. grounds.
Hope this helps,
Ed

[thehornshoppe]

Here is a crude drawing that should make it clear.
Ed

[Capt. Z]

Thanks for your ART work, Ed. Need to update/upgrade my magic cable. Since one of the 10 K resistors is no longer working and I need a longer version of the magic cable I will replace both with a 620 Ohm resistor and attach a longer cable.