Univox U45B adding a line out

[darrellcheng]

Hi all, I want to put a line out from my Univox for more volume when I need it. I found this, but I can't really decypher the wiring:

Since you're looking to put a jack in the vacant switch hole, I'm assuming that you want to use a jack and that you're looking to do a simple line level unbalanced output. OK, here's a simple circuit that we use for a "Slave" out on our 18W Budda amps. You'll first want to install a British (Cliff or Re-An) style jack; something with a plastic body that will keep the common connection isolated from the amp chassis. Mount the jack in the chassis and wire it as follows: Connect a 100 ohm resistor in parallel with a 0.01uf capacitor across the hot (tip) and common (sleeve) terminals of the jack. Connect an 820 ohm resistor from the tip of the jack to the tip of the speaker output jack. Connect a 22 ohm resistor from the common of the jack to the common of the speaker output jack. You now have a line level jack that will drive a power amp if you wish, has an output impedance of 100 ohm, is slightly hi-frequency compensated, and is 22 ohms isolated from ground which may help to prevent any ground loops between the interconnected pieces of gear. Now if you're looking to drive another guitar amplifier with this, it should be connected to the amps "effects return" input. If you're looking to put this signal into the guitar input of another amp, the signal is going to be too hot. To attenuate the signal you'll either need to substantially increase the value of the 820 ohm resistor, or you could substitute a pot for the resistor and set the signal for your needs. I'd try maybe a 10K pot and see if that drops the signal appropriately.

Does anyone know how to do this?

[Brad1]

Seems pretty straightforward to me. Maybe dissecting the thing in a better format will make sense? The blue entries tie together as the alternatives he mentions.

Quoted, but rearranged:
Since you're looking to put a jack in the vacant switch hole, I'm assuming that you want to use a jack and that you're looking to do a simple line level unbalanced output. OK, here's a simple circuit that we use for a "Slave" out on our 18W Budda amps.

1) You'll first want to install a British (Cliff or Re-An) style jack; something with a plastic body that will keep the common connection isolated from the amp chassis.
2) Mount the jack in the chassis and wire it as follows:

1. Connect a 100 ohm resistor in parallel with a 0.01uf capacitor across the hot (tip) and common (sleeve) terminals of the jack.
2. Connect an 820 ohm resistor from the tip of the jack to the tip of the speaker output jack.
3. Connect a 22 ohm resistor from the common of the jack to the common of the speaker output jack.

You now have a line level jack that will drive a power amp if you wish, has an output impedance of 100 ohm, is slightly hi-frequency compensated, and is 22 ohms isolated from ground which may help to prevent any ground loops between the interconnected pieces of gear.

Now if you're looking to drive another guitar amplifier with this, it should be connected to the amps "effects return" input.

If you're looking to put this signal into the guitar input of another amp, the signal is going to be too hot. To attenuate the signal you'll either need to substantially increase the value of the 820 ohm resistor, or you could substitute a pot for the resistor and set the signal for your needs. I'd try maybe a 10K pot and see if that drops the signal appropriately.

Brad1

[darrellcheng]

Hi thanks for the response. I don't have a speaker output jack in the amp, i only have a direct connection soldered to a speaker. How can I connect it this way?

[52 Bill]

I don't have a speaker output jack in the amp, i only have a direct connection soldered to a speaker. How can I connect it this way?

Trace the two wires that connect to the speaker. One will probably connect to a ground or common connection, and the other will connect to the output transformer and maybe a feedback loop. Use these points to connect the circuit that you build.

You could build the circuit in a small box of its own and just run two wires directly to the speaker itself. You should still check the connections to keep the ground and hot correctly wired.