Ground loop check turntable grounding
Hum in speakers
Hello all
I am trying to set up a modest audio system and cant figure out why there is a hum when I turn the volume up past 55. It only happens when there is vinyl spinning. If I turn volume up without vinyl on there is no hum. Below 55 volume the hum is not there.
note: I did set the speaker impendence to 6 ohm via the receiver settings.
Set up is:
- Sony STRDH190 2-ch stereo Receiver
- Warfedale Denton 80 Speakers (16 g speaker wire)
- Technics SL-1500C Turntable
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@dalims4 definitely a deep hum |
@yogiboy input #1 of 4 |
Try using the phono input on the Sony instead of the internal phono on the Technics. The speaker wires do not have to be bound together. BTW, you do not hook up the ground wire if you are using the internal phono on the Technics! Note • When you connect a turntable with a PHONO/ LINE switch, be sure to set the PHONO/LINE switch to PHONO. • This receiver equipped with Phono Equalizer amplifier to meet MM type PHONO cartridges. MM type cartridge used on turntable have a variation of audio output level. In case MM type cartridge output is small, you can use phono volume offset to increase the level (page 28). • To record the sound from the receiver, you must connect your device to the AUDIO INPUT 4 OUT jacks |
@yogiboy nope, same thing...this is so frustrating. I had a lesser quality turntable (audiotechnica lp60xusb) set up before this and didnt have this problem. I just dont get it
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Based on my own experience, I suggest you try a different set of interconnects. The first pair I used resulted in a not inconsequential hum. Then switched to a different pair and the hum was completely gone. I was told by the cable manufacturer that the particular interconnect was not shielded for turntable use. |
@jetter Ah, so I'll order shielded rca cables. thanks! |
I think I didn’t ask a clear question, so I’ll be a bit more specific by illustrating an experience I had. I had a wall wart (12v transformer) plugged into an extension cord lying on the floor behind my components. I had a cable from my pre-amp to my amp which was very close to the wall wart = hum. Moved the wart, end of problem. Components have internal transformers as well and if an RCA cable passes too close it can create a hum. It’s not just a matter of where your components are plugged into a wall. FWIW. |
@curiousjim I think its getting to that point for sure |
Thanks @jayctoy |
I would try a different circuit breaker when you change the plug for the TT, not just another outlet. Is it possible to turn the plug in the wall socket, sometimes changing the polarity will help (I have older TT's, always the first thing I try)? If the plug is "keyed", one wide one narrow blade you will not be able to do so. At the hardware store you can buy an inexpensive outlet tester (everyone should have one), it will look like an extension cord end. It will have LEDs on the back and the combination of the lights will tell if the wiring is correct, polarity, ground, etc. You probably are hearing 60 cycle hum, which is the frequency of A-C power. One outlet or lamp wired incorrectly, motor loads, nearby un-shielded transformers, bad ground or voltage on the neutral.....BTW some MM cartridges are "sensitive" do you have another to try? good luck |
The plug is keyed. I do have an outlet tester. I live in a pre war building so the wiring is most certainly off. I was thinking of just getting my electrician to run a new line just for my system as the wall where the system is against has no outlet and I'm plugging it all into an extension cord and power strip. Before I do that I'm thinking I will purchase a new Technics SL-1500C Turntable as this one is used. It might be worth the money as this one could be faulty. I think this is the way to go (?) |
My house was built in 1905, and two owners ago, had an Electrician in residence. As a result I am up to code, at least NEC from 20 years ago Consult with your electrician,,, A single breaker panel with a clean neutral and an isolated ground will do wonders. You will then have an orange, isolated ground, outlet, dedicated to a single use. Especially in older houses circuits are expanded, lighting added, extra outlets, and so on. All too often the ground is omitted altogether, and the neutral is picked up and used as a "common" wire and has too many connections on a leg which can lead to potential (Voltage) on the neutral, which is my SWAG for your issue, You might want to have an electrician look over your service, panels, wires and outlets/switches. Hope you're sitting down when you get the report. Having things brought up to code, though, will give you peace of mind (safety), improve the performance of your system and computers, AND increase the value of your home. Keep us updated, and good luck. |
@puptent Thanks again! |