I’ve tried various cartridge load settings. When using the 1 and 2 switch settings for a 47k ohm loading, it gets very raspy and the display says ad clipping. When I play around with the settings, I can get rid of the rasp, but then the sound becomes more muffled. I thought maybe there was a specific setting to switch between mm and mc cartridges, but I don’t see anything in the manual on this. I’ve tried the NPC with my Sprout, but I get the same results. When I run the turntable directly into the Sprout’s phono input, it sounds fine. My cartridge is an Ortofon Red, which has a recommended loading of 47k ohm. What am I missing?
My guess is that you need to adjust the cartridge gain in the NPC. I bet the gain is set to high for the output of your Ortofon which is a fairly high output MM cartridge. The instructions of how to do so are in your manual.
I agree with Elk. Lower the NPC gain setting through the front panel. The A/D clipping indicator is a good indication there’s too much gain. Let us know if this works or not.
Changing the gain setting worked. Thanks.
However, now I’m having a problem with hum. It only happens when the needle is on the record, which seems very odd. It goes up in volume when I turn up the volume on the processor. I’ve tried moving plugs around, and using a cheater plug, but no luck. I removed the turntable ground wire, and it gets much worse.
The NPC is connected using a coax digital cable to the processor.
I’ve moved the turntable back to the Sprout, and I don’t hear the hum nearly as much even with the volume turned up, so I don’t think it’s the cartridge.
What turntable are you using? Some turntables cut the signal from the cartridge when the arm lifts and this could explain your observation.
The hum from the turntable could come from a number of sources. Try some of these suggestions:
- Check the ground wire connection. Try moving the ground end of the wire to a different grounding point. Do you notice a change in hum when you touch the ground wire?
- Check the connections on the leads from the cartridge. Reseat or rotate the connectors if necessary.
- Check the phono cable connections at the turntable. Is there a junction box or do the cables come directly out of the tonearm?
- Verify that the cartridge mounting screws are tight and that the headshell is firmly connected to the tonarm (if there's a separate headshell, that is).
- Verify that the stylus is firmly seated in the cartridge.
- Is the hum the same in both channels?
- Does the hum occur if the motor is off?
- Does that hum get louder if the cartridge is closer to the motor?
The hum was from the DVR which was connected to the processor. If it was on there was a hum. Oddly enough, even if I turned it off, there was a hum for 5-10 minutes afterwards, which I think was due to the hardrive continuing to run for that period of time.
Thanks for the suggestions.
Cable TV connections are a very common source of ground loops and resulting hum.
Perhaps. All I can say is it only happened when playing vinyl. It did not happen when playing CDs or watching cable. The other odd thing is is only happened when the needle was in the grove. As soon as the needle left the groove, it stopped. I even unplugged the turntable and got the same result. Where is Telsa when you need him?
The ghost of Tesla transmitting power wirelessly?
Yes! Straight through the earth! I get my power from China.
Is the turntable on the same shelf/platform as the DVR? Given that noise is only coming through when the stylus is in the groove it could be mechanical noise being transmitted/conducted through the equipment rack or stand. Not sure what turntable you have but if you can isolate it from all other components and check again for noise it might help track down the source. I’m on the VPI turntable forum regularly and this sort of thing has been reported over there. For VPI tables with separate motors they recommend a mouse pad under the motor, not sure if that applies to your turntable, but it’s a thought.
Yes, getting the VPI motor away from the turntable helps. Mine is on a separate foundation from my Aries II. The motor lives on a shelf mounted to the wall while the Aries II is on a rack that sits on four concrete pillars set in the ground that emerge from a hole in the floor (hey, it was the wife’s idea!). A long loop of upholstery thread serves as a belt.
Awesome – talk about stability and isolation! But, when the time comes to sell your house, I wonder how the real estate agent will explain those concrete pillars coming out of the floor.
Well, they’re topped with a marble slab and there’s wood trim that conceals the hole, so it looks like a table. Like a weird, two-inch tall table. Next to the wall. Huh. I guess we’ll cross that bridge when we get there.
Pmotz, you were correct. The DVR is on a set of stacked shelves and is 2 shelves below the turntable. When I lifted the DVR off the shelf, the hum stopped. I was surprised that the vibration from the DVR harddrive could be picked up by the cartridge. Especially, considering the shelves are glass 1" thick. The shelves are on spiked feet too, which I think would isolate vibration to some extent. Fascinating.
Thanks for the suggestion!
Excellent detective work.
Glass is rigid and more than happy to transmit vibrations. The same is true of spikes.
Perhaps Vibrapods or sorbethane under the DVR will do the trick.
As a side note, I had a somewhat similar experience Sunday night, recording a vocal ensemble in a lovely old stone church. While inaudible sitting in the nave listening, there was a low rumble centered at 31Hz picked up the microphones. They were directly coupled to the stone floor through 15’ mic stands. Fortunately I can remove the noise with noise reduction software, but a great example of noise physically transmitted to and picked-up by a transducer.
r8schergen, glad to be of assistance. This is a perfect example of the audiophile obsession with isolation paying off in the end. And to think, most regular folks think we are crazy!
Think??? We ARE crazy!
I prefer to think of it as a fine line between sanity and insanity. Unfortunately, the line keeps moving…
r8schergen said I prefer to think of it as a fine line between sanity and insanity. Unfortunately, the line keeps moving.....And we keep chasing it like cats and laser dots on the ground . . .