SF Champ - Ext. Speaker Cab...?

[Tony]

Moving this from another section as it will probaby be a more "tech-y" thread.

I'd like to mod my SF Champ to push an external speaker cab (probably a 2x10, 4 ohm cab).

I'm a novice re: wiring, etc but want to learn more.

Anyone out there willing to talk a newbie thru the process of wiring this up?

Thanks...

[John Phillips]

All you need is a speaker cable with an RCA phono plug on one end - make sure it's a good one with a machined ground sleeve, not one of the flimsy ones with pressed 'leaves' - they don't make a reliable enough contact for speaker connections really... even though the amp's existing one will be this type. Or (better) you can replace the RCA jack in the amp with a 1/4" (it fits the hole), and put a 1/4" plug on the amp's own speaker cable.

Stick with 4 ohms for the cab BTW - 8 is risky for a Champ.

[Dana-L]

Hi Tony,

Running a Champ through bigger speakers truly unleashes the beast in these little babies; you're in for a sonic treat.

To do this with my own SF Champ, I built a short patch cable and what I call a 'parallel box' to allow me to connect two 8-Ohm cabs to the 3.2-Ohm output.

Here's a pic of the cable and box:

http://mysite.verizon.net/koitopia/ChampCableBox-02.jpg

For what you want, it sounds like all you need to do is build a patch cable and wire your 2x10 cab in parallel. Easy job.

To build the patch cable, get a male RCA connector (my favorite is a Neutrik brand which you can get at http://www.partsexpress.com (http://www.partsexpress.com/) along with all the other goodies you'll need), a 1/4" phone plug and a length of speaker cable. Parts Express sells some nice bulk cable under their 'Dayton' brand that's 14 AWG or so and is jacketed, unlike the individual insulated wires I used in the example above. You can also get heavy wire and cable by the foot at Home Depot that works very well. Anyway, to make the patch cable all you need to do is solder the same color wire to the tip connections of each connector and then repeat for the sleeve connections.

If you want to use individual wires like I did, get some tinned wire (it's much easier to solder) in whatever colors you like. Any insulated and stranded wire from 12 through 18 AWG should work fine. For a vintage look, http://ww.tubedepot.com (http://ww.tubedepot.com/) sells some cool, cloth-covered wire with modern insulation underneath. To get a nice twist on it, clamp both wires into a bench vise, tighten the other ends into the chuck of an electric drill, and spin them slowly until they're the way you want them. Unfortunately, I didn't learn this trick until after I'd built mine...

To wire the cab, simply run wires from each of the positive terminals on each speaker to the tip connection on the 1/4" jack on your speaker cabinet and solder them in. Do the same with the negative connections, soldering them both to the sleeve terminal of the 1/4" jack and you're done.

Have fun!

-Dana

[Tony]

hey guys; thanks for the input!

john - is the RCA phono to 1/4 something i can just pick up at Radio Shack?

dana - wow; thanks for all the detail. i am looking at a 4 ohm cab, so i think i s/b ok on the ohm side of things.

lastly - forgive me; i don't have the champ here at "work" with me. do i need to open the amp up to do any of this?

thanks again.