Hum-free relays?

[Leevi]

Are there any? I think the relays cause always more or less hum if you use them
for signal switching. I worked around one problem by adding more filtering to the voltage supply and
by changing the rectifier from a half-wave to full-wave. Maybe the reason is that the relays
I have been using are not meant for audio use?
/Leevi

[phsyconoodler]

  I have built many amps with 5v omron relays and there is no hum associated with their use.

  I use diodes to prevent bleed.The voltage supply doublers have filters as well.Where you ground everything has more to do with noise than the relays.

[jerrydyer]

you want to try one of these instead. ? 

[JayB]

Have to keep the grounds for the relays away from anything else. I would ground them around the jack your using for the foot switch. Every time I grounded them with the filter caps or on a buss wire across the pots, it was hum. Not so bad grounded with the filter caps but you could still make it out.



Jerry, what is that? Cool looking amps your building. Those knobs your using look like those pilot light jewels. To bad you can't make them light up.

[G._Hoffman]

Well, I haven't built a lot of amps, but the ones I've put relays in have never had hum FROM THE RELAYS.  (Ahem...)

On the one I just finished, I didn't have quiet enough current available from the heater taps, so I added a small additional transformer, and (mostly because I already had all the parts available, and PCB designed) I went ahead and used a 7805 regulator for the relays power supply.  I also used the protection diodes on the relays.  The relay PS is, now that I think of it, floating, which I should probably take care of.  At any rate, the relays is completely silent for me.


Gabriel

[bluesbear]

I've always used the Weber relays and never had any hum at all.Thankfully!
Dave

[Leevi]

I have totally different experiences and it's not the first time I'm fighting with that. Note that the hum
doesn't occur with lower amplification. I tested my case by adding more filtering for the relay voltage supply during operation and could
clearly hear that the hum decreased. Certainly the grounding and voltage stabilization play affect that. Maybe a good solution could be
that the control voltage is separated totally from the amp grounding. But then you should use isolated jacks for
the relay control. There might be a logical reason for the hum: The hum is emitting from the
relay coil to the couplers and through that to the signal way? In order to minimize the hum a good DC voltage supply is needed.

It's not only me who have had these kind of problems:
http://music-electronics-forum.com/t6437/

/Leevi

[G._Hoffman]

I have totally different experiences and it's not the first time I'm fighting with that. Note that the hum
doesn't occur with lower amplification.

Well, if you are using it for a channel switch, you wire the relay so the higher gain channel is active when the relay coil is off.  That way, when the coil is active, you have less gain and less issues with noise.


Gabriel

[Leevi]

I have in total 5 relays in my last amp and I'm using them for adding more
amplification stages (boost), for controlling reverb and boost volume. The biggest hum
is caused by the relay that switches an extra 1/2 triode to the preamp stage.
I'm always using a small capacitor over the voltage pins of the relay in order to minimize snap.
/Leevi

[bluesbear]

"wire the relay so the higher gain channel is active when the relay coil is off"

I always do just the opposite so the amp is still usable if the relay croaks. Still no hum, though. Maybe I'm just lucky or (dare I say it?), maybe I'm just good!  

Dave

[Leevi]

I grounded the relay coils to a separate star grounding point and the hum level decreased little bit.
/Leevi

[phsyconoodler]

How's Leevi doing these days?He looks sad in the picture

[Leevi]

Leevi is fine after the backbone was operated. He is now 13 years old and is not so sad as in the picture.
Leevi's master

[jerrydyer]

Have to keep the grounds for the relays away from anything else. I would ground them around the jack your using for the foot switch. Every time I grounded them with the filter caps or on a buss wire across the pots, it was hum. Not so bad grounded with the filter caps but you could still make it out.



Jerry, what is that? Cool looking amps your building. Those knobs your using look like those pilot light jewels. To bad you can't make them light up.

thats a switch board that controls 8 vactrols    almost endless switch shun directional etc everything type invention. I have bad luck with relays. The nobs are the standard fancy Q Parts stuff