Mains Hum from TX-1?

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Neither
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Mains Hum from TX-1?

Post by Neither » Fri Jun 07, 2019 11:15 am

I've moved to a new apartment. Now I'm devastated to find out that I can't use TX-1. My favorite distortion pedal. It outputs a very loud mains hum. I didn't have this problem in my previous apartment. Both places had ungrounded AC-plugs. I don't think the cause for the mains hum is in my equipment because it's the same as in the old house. I've tried several different cables and turned off any extra electric devices. I've tried different AC-plugs. Even in different rooms. The hum goes on.

What can I do to solve this problem? This is the first time I've run into something like this.

I'm using this Peaktech psu from Schneidersladen:
https://peaktech-rce.com/en/universal-p ... v-16a.html

edit: I dragged my equipment to a room with grounded mains plugs. Didn't help so that doesn't seem to be the problem.

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Post by metasonix » Fri Jun 07, 2019 4:13 pm

This sounds like possible defective household mains wiring. The earth-ground connections might be floating or the hot and neutral wires might be reversed. That would be REEEEALLY BAD and you need to have a licensed electrician check the wiring for such problems. It's a major safety hazard. If the landlord won't check it, file a complaint with the local government building inspector.

It is also possible that something on your branch circuit is generating noise and injecting it back into the circuit as waveform distortion. Sometimes by defective lamp dimmers or appliances, sometimes by a bad computer switching power supply. Disconnect things and shut off circuit breakers for circuits other than the studio mains to find the cause.

Are you sure the TX1 wasn't damaged in moving? Same for the PeakTech power adapter, right? Watch out for neighbors with bad appliances.

Otherwise there's not much else I could suggest. It is possible to modify the TX1 to run on external DC supplies, but this is NOT easy. It needs +12v, -12v and +95v.

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Post by Neither » Fri Jun 07, 2019 5:22 pm

metasonix wrote:This sounds like possible defective household mains wiring. The earth-ground connections might be floating or the hot and neutral wires might be reversed. That would be REEEEALLY BAD and you need to have a licensed electrician check the wiring for such problems. It's a major safety hazard. If the landlord won't check it, file a complaint with the local government building inspector.
Oh no, this is something I was afraid of. I've had weird problems with electricity elsewhere also. I'll get a licensed electrician check the wiring ASAP.
It is also possible that something on your branch circuit is generating noise and injecting it back into the circuit as waveform distortion. Sometimes by defective lamp dimmers or appliances, sometimes by a bad computer switching power supply. Disconnect things and shut off circuit breakers for circuits other than the studio mains to find the cause.
My studio doesn't even have a lamp on the ceiling. All the other lamps have been disconnected while testing. And the computer has been off. Also no dimmers.
Are you sure the TX1 wasn't damaged in moving? Same for the PeakTech power adapter, right? Watch out for neighbors with bad appliances.
I packaged TX-1 in a large box filled with styrofoam pellets while moving. It was packaged so good that I can't imagine any scenario how it could have been damaged.

Thank you for your detailed answer. And thanks for your warning.

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Post by Neither » Sat Jun 08, 2019 5:28 am

I've got a "transformer center" right next to my studio. Or what ever they are called. This kind of building:
Image

The distance is around 10 or 15 meters.

I was thinking perhaps it could cause the AC hum? Though the hum isn't transmitted to my other tube gear (R-52, RK3 and R-56) running on EP-360 Power...

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Post by Neither » Tue Jun 18, 2019 5:08 am

Seems like Malekko SND/RTN is the cause of my suffering. It worked fine with TX-1 in my old apartment. Now it also works fine with other pedals (battery powered). I've also connected SND/RTN to different power rails and power source but the hum goes on.

When I plug my gear straight into TX-1 (without going first through SND/RTN) - there is no hum. Is the SND/RTN or any DI-solution even really necessary with TX-1..?

I'm not sure if this is normal or should I still consider calling an electrician? I don't understand much about electricity as you can probably see.

edit: I also remember that my previous apartment had ungrounded power sockets. Like this:
Image
I would have thought that those kind of sockets are more likely cause interference. This apartment has grounded sockets. Or at least these sockets have the grounding pins...

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Post by metasonix » Wed Jun 19, 2019 9:05 pm

Neither wrote:I've got a "transformer center" right next to my studio. Or what ever they are called. This kind of building:
Could easily be a problem.
Seems like Malekko SND/RTN is the cause of my suffering. It worked fine with TX-1 in my old apartment. Now it also works fine with other pedals (battery powered). I've also connected SND/RTN to different power rails and power source but the hum goes on.
Well then the Malekko pedal is bad. Possibly a broken ground wire inside.

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