Passive Balanced switching and Relay questions!!

[JAY X]

Hi All,

MECHANICAL SWITCHING

I'm currently switching balanced line level audio signals with alps 4pdt switches. This model allows me to switch between TWO sources, and works very well.Ok so far.

To switch between THREE balanced sources is more complicated. I would need a LORLIN CK switch, but i don't know which model to choose. (3 pole or 4 pole, or any other...). The grounding scheme i usually use is the classic "Ground follows signal". I need a model suggestion.

RELAY SWITCHING


Recently i started switching audio line level signals with relays, (TAKAMISAWA RY24-K) 10 pin DPDT relays, with a 1n4148 diode across the coil. Powered with 18volts. ¡¡I'm a newbie with relays!!

I wire it up as i would do with a mechanical switch, taking care of the usual considerations relays need.

Once wired,(as a mute switch or a changeover switch) i test it and pass some audio thru it, and the result is not bad, (a bit harsh),but not that transparent as a mecahnical switch. ¿is this normal?

I switch signals coming out from a low impedance output OPAMP, to a High impedance input Opamp. ¿Do i need to put input resistors? (10k or so?) to the inputs of the relay?? Maybe i'm getting confused now...

Thank you for your help,
JAY X

[JAY X]

Hi,
Maybe i don't have explained myself well.
I just have two questions:

1) I'm looking for a Rotary switch to select from 3 balanced sources
¿any maker/model?

2) when switching audio line level signals withs relays, the sound is a bit harsh, with a loss in low frequencies. ¿Is that normal?

The relay i use is a TAKAMISAWA A24W-K powered from 18v supply. The setup test: CD PLAYER----> RELAY-----> AKG 240 HEADPHONES.

Thank you for your help,
JAY X

[raudio1969]

Hi Jay,

Here is a 4 pole, 3 position rotary switch.

Digi-Key - 451-1030-ND (Manufacturer - C5P0403N-A)

- Richard

[shanx]

2) when switching audio line level signals withs relays, the sound is a bit harsh, with a loss in low frequencies. ¿Is that normal?

The relay i use is a TAKAMISAWA A24W-K powered from 18v supply. The setup test: CD PLAYER----> RELAY-----> AKG 240 HEADPHONES.

The relay contacts you have on that W-K model should be good, gold plated etc, but you maybe a bit low on the operating voltage you are switching the coil with. The guaranteed must operate is at 16.8 VDC and your supply is only 1.2 V above that so might not be applying a good holding current..you could try the version with 18 VDC nominal RY 18 W-K. are you controling with a mechanical switch or electronically?

If you are hearing an audible click you could try using a 1 Meg resistor across signal and ground, after the switch towards input side of your preamp. That can help, reduces some transients and pops from capacitors discharging and charging when you switch sources, and doesn't load down signal too much.

[shanx]

2) when switching audio line level signals withs relays, the sound is a bit harsh, with a loss in low frequencies. ¿Is that normal?

The relay i use is a TAKAMISAWA A24W-K powered from 18v supply. The setup test: CD PLAYER----> RELAY-----> AKG 240 HEADPHONES.

The relay contacts you have on that W-K model should be good, gold plated etc, but you maybe a bit low on the operating voltage you are switching the coil with. The guaranteed must operate is at 16.8 VDC and your supply is only 1.2 V above that so might not be applying a good holding current..you could try the version with 18 VDC nominal RY 18 W-K. are you controling with a mechanical switch or electronically?

If you are hearing an audible click you could try using a 1 Meg resistor across signal and ground, after the switch towards input side of your preamp. That can help, reduces some transients and pops from capacitors discharging and charging when you switch sources, and doesn't load down signal too much.

[AndrewT]

If the sound coming through the Mechanical switch is different from that coming through the Relay switch, then I would suggest it is down to the self cleaning of the switch contacts in either case.
The forces between the contacts and the method of "wiping" will be quite different. Whereas the materials used for the contacts and for the poles to the outside world could be sourced to be identical. The materials should not change the sound if they are the same.