Hey all.
Interesting problem...
I have a 120 Hz hum/noise on my phono amp.
The amp in question is a stand alone tube based RIAA stage which feeds a tube based line amp, and into tube monoblocs. All grounded to earth. The RIAA amp is grounded to earth via the line amp.
After trying several of the normal troubleshooting techniques the following is the case.
In this context "no noise" mean the specific hum/noise when all is connected.
No noise, input shorted.
No noise, cable disconnected from turntable.
No noise, headshell removed from tonearm.
This makes me feel like it's EMI picked up by the coil in the cart. Sadly, all of my phono carts are either Pickering or Stanton, and all the same or similar design.
The turntable is a Stanton ST-150 with the internal connection between the cartridge and the internal amplifier disconnected. (Traces cut)
The ground is lifted on the turntable (by a switch built into the deck, the rest of the device is grounded). Connecting this ground ads a 60Hz component.
It's not loud per se. It's close to the level of the noise of a new record on the lead in. I just HATE buzz!
Any ideas? Besides moving the deck to a field in the country and using batteries, that is... 🙂
Interesting problem...
I have a 120 Hz hum/noise on my phono amp.
The amp in question is a stand alone tube based RIAA stage which feeds a tube based line amp, and into tube monoblocs. All grounded to earth. The RIAA amp is grounded to earth via the line amp.
After trying several of the normal troubleshooting techniques the following is the case.
In this context "no noise" mean the specific hum/noise when all is connected.
No noise, input shorted.
No noise, cable disconnected from turntable.
No noise, headshell removed from tonearm.
This makes me feel like it's EMI picked up by the coil in the cart. Sadly, all of my phono carts are either Pickering or Stanton, and all the same or similar design.
The turntable is a Stanton ST-150 with the internal connection between the cartridge and the internal amplifier disconnected. (Traces cut)
The ground is lifted on the turntable (by a switch built into the deck, the rest of the device is grounded). Connecting this ground ads a 60Hz component.
It's not loud per se. It's close to the level of the noise of a new record on the lead in. I just HATE buzz!
Any ideas? Besides moving the deck to a field in the country and using batteries, that is... 🙂
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I think this is the case - the cartridge coil catches the surrounding field....even the phono preamp with batteries does not help...sometimes it depends on the shape of the headshell - it also act as screen...
Since you say 120Hz hum it is not the cartridge pickup of 60Hz. I sure would look for PS problem, like poor ground and bad layout of the PS.
Duke
Duke
I suggest you buy one of these BIC 940 turntables.
VINTAGE BIC TURNTABLE 940 RECORD PLAYER WORKS W/Manuals - 1975 | eBay
I have one and it doesn't hum at either 60 hz or 120 hz. Still working after 40 years regular use. Tracks at 1.5 g.
e-bay listing expires tomorrow.
They went bankrupt because they looked like garbage. they weren't.
I use a Shure M97 Era IV cartridge.
VINTAGE BIC TURNTABLE 940 RECORD PLAYER WORKS W/Manuals - 1975 | eBay
I have one and it doesn't hum at either 60 hz or 120 hz. Still working after 40 years regular use. Tracks at 1.5 g.
e-bay listing expires tomorrow.
They went bankrupt because they looked like garbage. they weren't.
I use a Shure M97 Era IV cartridge.
The power supply is switching in the kHz range, and if it was the power supply, it would hum wildly without any input connected in my experience...
That deck looks alright, but it doesn't spin at 78 RPM, or ship to Canada.
For the record, I get the same "noise" if I try to tune AM radio in here. The entire band is this noise.
I assume there are NO good sounding crystal cartridges? 😛
Also annoying is that on the other deck (which is still connected internally) I get no noise if I use the built in RIAA amp, but the amp sounds worse than the tubes...
That deck looks alright, but it doesn't spin at 78 RPM, or ship to Canada.
For the record, I get the same "noise" if I try to tune AM radio in here. The entire band is this noise.
I assume there are NO good sounding crystal cartridges? 😛
Also annoying is that on the other deck (which is still connected internally) I get no noise if I use the built in RIAA amp, but the amp sounds worse than the tubes...
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Make sure that blue and green or white and red are not interchanged on cartridge.
You can check with ohmmeter at the RCA plug side, but be careful not to damage the coils.
You can check with ohmmeter at the RCA plug side, but be careful not to damage the coils.
I'll check that, thanks. I'm in the process of moving the power supply to another chassis. I'll connect them with a cable, and get rid of some of the heat. There was a failing cap that got hot enough to melt it's solder and fall out of the board! Never saw that before...
The trouble with the crystal cartridges I've owned, they rip the highs off an LP in one play. Tracked at 5 g. A new one did the same thing to the records.
Not a lot of reviews of crystal cartridges, but I'd say the 5 g tracking is a lot of risk to PVC ridges.
Check nearby equipment isn't radiating noise.
I had a phone base that I couldn't keep in same room as turntable. Sounded just like 100/120Hz buzz.
I had a phone base that I couldn't keep in same room as turntable. Sounded just like 100/120Hz buzz.
Thanks all... It seems that moving the DC boost converter and delon voltage doubler to another chassis and connecting by a cable has sorted the issue. Quiet enough now that I could forget it's even on.
Right now I'm tracking at 3 grams. I play 78's with about 5 grams or so though 🙂 In this case, I'm using a Pickering 625e cartridge with an actual Pickering 625 DJ which seems to be the same as the original 625E stylus.
Right now I'm tracking at 3 grams. I play 78's with about 5 grams or so though 🙂 In this case, I'm using a Pickering 625e cartridge with an actual Pickering 625 DJ which seems to be the same as the original 625E stylus.
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