Hum from speakers

[senguptamitava]

Hi all,
I am facing a peculiar problem with my turntable setup.
I use AT LP 120 USB paired with Sonodyne SIA 102 R amp And Sonodyne speakers
Recently it has started that whenever I crank up the volume a bit loud there is a loud BASS hum from the speakers. As soon as the cartridge is lifted it is off. It starts at different volume levels for different cartridges eg AT 3600L and Ortofon 2M red
can anyone help me out of this situation?
Regards,
Amitava

 

[General_sound]

There are many reasons for the hum. Go step by step, to isolate the problem. However take precautions i.e. switch off the system from mains to avoid electric shocks, double check all connections before switching on system again, taking particular care about speaker connections to avoid inadvertent shorting if using bare wire.
1. Isolation. In case speakers are too near or placed on the same table, then do isolate or increase distance. Turntable can also be isolated using various means. Feedback or howling sound from speakers is mostly due to isolation problems.
2. Earthing and loose connection. Recheck earth lead , if available on the tt. The RCA jacks should not be loose. The headshell should be firmly tightened. No force anywhere.
3. You may get the cartridge pins( on the headshell) checked for looseness .
4. Does your amp or phono stage have a rumble filter? You may try to switch on. Many integrated amps and phono stages have a built in filter. Some do not, Shitt Mani Version 1(older) being an example.
Please do the above only if you are familiar with electronics otherwise check from a technician.
Hope that helps.

 

[manek]

There are many reasons for the hum. Go step by step, to isolate the problem. However take precautions i.e. switch off the system from mains to avoid electric shocks, double check all connections before switching on system again, taking particular care about speaker connections to avoid inadvertent shorting if using bare wire.
1. Isolation. In case speakers are too near or placed on the same table, then do isolate or increase distance. Turntable can also be isolated using various means. Feedback or howling sound from speakers is mostly due to isolation problems.
2. Earthing and loose connection. Recheck earth lead , if available on the tt. The RCA jacks should not be loose. The headshell should be firmly tightened. No force anywhere.
3. You may get the cartridge pins( on the headshell) checked for looseness .
4. Does your amp or phono stage have a rumble filter? You may try to switch on. Many integrated amps and phono stages have a built in filter. Some do not, Shitt Mani Version 1(older) being an example.
Please do the above only if you are familiar with electronics otherwise check from a technician.
Hope that helps.

Decades ago I remember this happening to my Garrard TT. I am sure this is not an uncommon a problem. The earthing screw at the amp end was loose on the chasis. So stripping and cleaning the exposed earthing wire end and tightening the earth screw to the amp chassis fixed the electrical issue.

In addition to the points above :
If placing your speakers further away is a option and do try it.

Dry solders on the rca interconnects ? Motor hum ?

If you have any other sources connected to the amp disconnect them from the amp amp try. Is there a power cord close to the interconnects ?

 

[senguptamitava]

There are many reasons for the hum. Go step by step, to isolate the problem. However take precautions i.e. switch off the system from mains to avoid electric shocks, double check all connections before switching on system again, taking particular care about speaker connections to avoid inadvertent shorting if using bare wire.
1. Isolation. In case speakers are too near or placed on the same table, then do isolate or increase distance. Turntable can also be isolated using various means. Feedback or howling sound from speakers is mostly due to isolation problems.
2. Earthing and loose connection. Recheck earth lead , if available on the tt. The RCA jacks should not be loose. The headshell should be firmly tightened. No force anywhere.
3. You may get the cartridge pins( on the headshell) checked for looseness .
4. Does your amp or phono stage have a rumble filter? You may try to switch on. Many integrated amps and phono stages have a built in filter. Some do not, Shitt Mani Version 1(older) being an example.
Please do the above only if you are familiar with electronics otherwise check from a technician.
Hope that helps.

Thanks for your suggestions. Space is a real constraint in my room. The speakers are placed 2 ft away from the turntable and they are floor standers. Earthing cable and headshell has been checked . My amplifier doesnt have a rumble filter. Overall it is very annoying.

 

[manek]

Thanks for your suggestions. Space is a real constraint in my room. The speakers are placed 2 ft away from the turntable and they are floor standers. Earthing cable and headshell has been checked . My amplifier doesnt have a rumble filter. Overall it is very annoying.

My guess is it could be interference from speakers. If the speaker cables have some length to them please bring the speaker out(away from the back wall) temporarily to ensure its not the speakers causing the issue. If cable lengths are short any cheap long speaker cable will do just to check. Check for any other magnetic devices near TT.

Hum is always addressed by a process of elimination and patience.

Is it a deep hum(50-60hz) or a less lighter buzz(120hz) one ?

 

[mbhangui]

The noise comes only when the platter is moving indicating motor noise. Watch these two videos

 

[manek]

The noise comes only when the platter is moving indicating motor noise. Watch these two videos

wow ! All AT LP 120 usb’s ?

 

[senguptamitava]

My guess is it could be interference from speakers. If the speaker cables have some length to them please bring the speaker out(away from the back wall) temporarily to ensure its not the speakers causing the issue. If cable lengths are short any cheap long speaker cable will do just to check. Check for any other magnetic devices near TT.

Hum is always addressed by a process of elimination and patience.

Is it a deep hum(50-60hz) or a less lighter buzz(120hz) one ?

Its a deep hum (50 to 60 Hz)

 

[manek]

Its a deep hum (50 to 60 Hz)

Ok. How much of all the above reco’s from forum members have you done so far ?

 

[mbhangui]

Its a deep hum (50 to 60 Hz)

If you are sure this is 50Hz sound, then this won't be the motor issue described above.

There are three ways to connect this TT

1. Connect the TT directly to line in of amp. This will be RIAA equalized. For this the switch at the back has to be set at "LINE" position. I believe this is how you have connected your turntable to your amp.
2. Connect the TT to an external phono preamp or if your amp has phono input. This output will be most prone to pick up noise if there are ground issues
3. Connect the TT using a usb cable to your computer. You can either run the audacity program or use whatever kind of control panel you have to select sound from the USB device played to the computer speaker. If your computer has a line out, the computer can be connected to the amp

Also slide the switch on the back for 5-6 times between phono and line just to eliminate contact issues.

If you can try all the above 3 outputs you can eliminate where the noise is being generated.

 

[reubensm]

The easiest way to check if your turntable is picking up feedback from the speakers - just plug in your headphones and turn off the speakers (if they aren't turned off automatically when you plug in the headphones). If your turntable is being effected by feedback, you should not hear this booming hum when using headphones.

With the risk of sounding pessimestic, hum/static/grounding issues in turntables are tricky issues to resolve as the causes can be many and the resolution different for each cause. The ability to diagnose and isolate is the key to resolution.

 

[senguptamitava]

Its feed back from speakers. Placed the speaker further and the hum decreased considerably. Now when there is hum, pressing the table on which the tt is placed is eliminating the hum totally. Confused but why should the blank places in the record or just when the stylus is placed on the record without spinning create a Hum?