[Dan the audioman]

I am currently building my PIMETA and would like to add a er4p to s converter into the amp (as I will primarily be using the amp with my etys) which can either be turned on (converted) or bypassed via a switch.

How would I hook it up? What kind of switch would I use?

thanks

 

[davei]

Use a DPDT toggle, the common of each side going to the input jack, one lug going to one end of a 68 ohm resistor, other end of the resistor goes to the circuit input. Then take the other lug of one side of the toggle and hook it directly to the circuit input.

 

[Dan the audioman]

It goes to the input jack? As in the headphone input or the source input?

 

[tangent]

It's probably easier to run the common lugs to the amp board's output pads, and put the resistors on one side of the switch and direct connections on the other side. It's a question of whether it's easier to double up wires to the output jack or to the output pads on the amp board.

Another scheme you might consider is using two separate output jacks, one with resistors inline with the left and right lugs, the other plain. The parts for this are cheaper, and the wiring is shorter since you can just connect the two jacks together. The wires from the output pads on the amp go to one jack, and then you solder the resistors directly from one jack to the other. This works best if the two jacks are side by side.

Regarding the resistor value, the 4Ps are 27 ohms, and the 4Ses are 100 ohms, so a 75 ohm resistor is a closer match to ideal. You'll find more uses for spare 75 ohm resistors as well, as they are commonly used for terminating video circuits.

 

[Dan the audioman]

Ok, I get this now....But should I instal it before of after the amplification...does it make a difference?

 

[Dan the audioman]

Here is my awful drawing on paint to organize this (let me know if i am incorrect): Ahh nevermind i cant post in....

 

[davei]

Quote:

Originally posted by Dan the audioman Ok, I get this now....But should I instal it before of after the amplification...does it make a difference?

Before. It has to be wired at the input jack (headphone input jack), inline with your headphones. So after amplification.

 

[tangent]

Calling the headphone jack the "input jack" is just plain wrong, davei. Headphones are passive, they provide no signal. Therefore their jack is an output. The input jack on an amp is the one going to your source.

 

[Dan the audioman]

Thanks for clearing things up tangent. Well...I better get started!

thanks guys

 

[davei]

Quote:

Originally posted by tangent Calling the headphone jack the "input jack" is just plain wrong, davei. Headphones are passive, they provide no signal. Therefore their jack is an output. The input jack on an amp is the one going to your source.

My mistake, thanks for the clarification!