Custom Pedal Switch Build - Tone affected by relay

[phos81]

hi,

I'm building a customized guitar pedals switch. I tried two different kinds of relays, first I tried with the TQ2-5V-3 Panasonic Low Signal Relays - PCB but when driving the guitar signal through it changed the tone significantly lowing the treble and making it a little dark. I read in another forum that is best for this kind of projects to use reed relays so I bought some Hasco 711-5S. But even when they work better in terms of tone I still notice a slight change in the tone lowing the trebles.

The tests I'm doing are connecting a female jack to each line pin of the relay and of course 5V power. Nothing else.

Does anyone knows If I'm missing some kind of filter or signal booster that needs to go along the relay?

Thanks in advance,

[mozz]

Impossible. Well, not. Get a lcr meter and see what your bypassed capacitance is.

[nosaj]

How does it sound with a band? Its kind of like taking a movie singling out one actor editing the video to only show the actor. Real easy to get nit picky when your not looking at the whole package.
What seems noticable with just a guitar gets lost in a mix.
nosaj

[Enzo]

And are you sure it is the relay itself? Switching systems often add more wiring and stuff, so you could ding your stuff surrounding the relay is dragging you down. Like the difference between a 6 foot guitar cord and a 30 foot cord.

An experiment: remove the relay and solder a jumper wire in its place. This to simulate the condition. Now does plugging a guitar through it still lose anything? Or does it now sound transparent?

[J M Fahey]

Relays are flat: either open or closed and a few pF capacitance across contacts which "do nothing".

But as mentioned above,if they add a few feet of highisjh capacitance cable ....

[phos81]

Thank you for all the answers, I'll follow them and respond accordingly each one.

[phos81]

Impossible. Well, not. Get a lcr meter and see what your bypassed capacitance is.

Thanks but I don't have an LCR meter and would be more expensive than the project.

[phos81]

How does it sound with a band? Its kind of like taking a movie singling out one actor editing the video to only show the actor. Real easy to get nit picky when your not looking at the whole package.
What seems noticable with just a guitar gets lost in a mix.
nosaj

I am little picky, you're right about it but I want a clean sound.

[nosaj]

Lots of affordable options here
nosaj

[phos81]

And are you sure it is the relay itself? Switching systems often add more wiring and stuff, so you could ding your stuff surrounding the relay is dragging you down. Like the difference between a 6 foot guitar cord and a 30 foot cord.

An experiment: remove the relay and solder a jumper wire in its place. This to simulate the condition. Now does plugging a guitar through it still lose anything? Or does it now sound transparent?

You were right. I did the experiment but instead of removing the relay I changed the wiring and connection. I had common internal guitar cable (non shielded) with female jacks, now I put an instrument cable with male jacks plugged directly to amp and guitar. And I hear no tone change!!!

So thanks, as you and juan Manuel said, the relay is not changing the tone. However I'm worried now because the cable I used for the first testing is the same I have used for wiring guitars inside. So, that makes me wonder what kind of wire am I using and what should I have used?????


Thank you all, I am in a good path now.

[Helmholtz]

That Mogami cable is high quality and the added capacitance should be insignificant.

But like other low noise cables is has a black conductive plastic sleeve that is in contact with the shield.
If that sleeve is not cut back carefully it might contact the inner conductor somewhere and thus cause some "leakage" resistance between tip and sleeve.
You can use your Ohmmeter to find out.

[solarbass]

Glad you got it figured out!
Just a quick note on relays for small signals. I once had a project to design some data acquisition gear for small signals, we put a power relay in there with silver oxide contacts that could handle like 10 amps.
We had lots of distortion issues with the small signals, like 100mVpp.
Come to find out the contact materials of relays can insert unwanted impedance into the circuit. Power relays can sometimes require up to 100mA current flow to establish a connection - below 100mA contacts are just an open circuit.
Looking on Digikey I see contact materials good for small (millivolt) signals are: Gold, GoldCobalt, Palladium, Rhuthenium, Palladium Nickel, Rhodium.
So keep in mind not all relays are equivalent, and check the contact materials and intended use of the relay.

[Helmholtz]

Glad you got it figured out!
Just a quick note on relays for small signals. I once had a project to design some data acquisition gear for small signals, we put a power relay in there with silver oxide contacts that could handle like 10 amps.

I could imagine silver oxide to act as a semiconductor producing a Schottky contact with a threshold voltage.
Result would be low level signal distortion.

[g1]

I'm worried now because the cable I used for the first testing is the same I have used for wiring guitars inside. So, that makes me wonder what kind of wire am I using and what should I have used?????

Is the picture the wire that fixed the problem?

[Chuck H]

All the above, and...

The only lead wire in your guitars that should be shielded are the bundled pickup leads getting into the guitars electronics cavity. After that the cavity should be shielded and grounded at the bridge and all other grounded circuits should join at that connection. If this is what you've done there's nothing to worry about.

I would have built that switch box with plain ol hookup lead in a metal box to act as a shield. I would have floated the leads in a way that keeps them separated from each other and the box. Any shielded lead adds capacitance. In this case it's an insignificant amount as Juan noted. But if you're picky, and your mind won't rest unless you know it's as good as possible... You've added capacitance as it is and therefor it's like you're using a slightly longer guitar cable. Plus whatever cable/s you are additionally employing to use the switcher.