A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
I think it is very safe to say that this is a torture test and most MC users will not have anything like that level of mains fields anywhere near their turntables. I'll take two!
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Wow. That is impressive, especially after learning about the the details of the hum torture chamber you are running it in. That's a lot of gain and a lot of cable with all that stray field around. I think I might need one too.
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Very nice!
Best,
Doug Williams
Electromagnetic Radiation Recorders
Doug Williams
Electromagnetic Radiation Recorders
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Looks good Wayne. I think my DL103 into your MM preamp with a Lundahl 1:8 stepup is about the same. I don't have FFT setup yet so I can't quite do an apples to apples comparison.
I've been quite happy with this setup. I think I have a resonance around 10K. I underdamped the cartridge because to it sounded constrained fully damped. It's probably due to that.
I've been quite happy with this setup. I think I have a resonance around 10K. I underdamped the cartridge because to it sounded constrained fully damped. It's probably due to that.
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Hi Wayne
Is the “HUM” Electrostatic or Magnetic? What is the difference in FFT by wrapping the pickup in Alum foil vs putting it in a steel paint can and closing the lid? What is your area lighting type? Incandesce, fluorescent tube or switching fluorescent / LED type?
Duke
Is the “HUM” Electrostatic or Magnetic? What is the difference in FFT by wrapping the pickup in Alum foil vs putting it in a steel paint can and closing the lid? What is your area lighting type? Incandesce, fluorescent tube or switching fluorescent / LED type?
Duke
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Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Thanks everyone!
It's magnetic. Aluminum does nothing.
Lighting is all LED and it occurs with them off.
The hum hot spot are the huge transformers, running with a fair degree of core saturation, in the APC UPS units.
My magnetic hum sniffer (a telephone pickup coil and battery-powered R-S amp) also nulls to the exact same angle in the field.
It hums like a b*tch near the APCs.
Guitar pickups are also a problem in this room as well as the spring reverb.
Quite a bit comes from ingress into the DL-103 itself.
I'm not worried about it: In this particular case you wouldn't want to monitor at a level where you could actually hear it.
If the needle were to drop or the platter start spinning the monitors would be destroyed.
I actually ran gain up in a deep fade to listen to the noise floor, couldn't hear it beneath the surface noise, and quit afraid I would run into the intro of the next cut.
I'm not going to spend any time on it right now because as a practical matter its so deep in the mud as not to matter.
I do want to get some mu-metal to quieten the spring reverb and I'll try lining the metal Hammond box with it.
Not sure I can do much to shield the DL-103.
It's magnetic. Aluminum does nothing.
Lighting is all LED and it occurs with them off.
The hum hot spot are the huge transformers, running with a fair degree of core saturation, in the APC UPS units.
My magnetic hum sniffer (a telephone pickup coil and battery-powered R-S amp) also nulls to the exact same angle in the field.
It hums like a b*tch near the APCs.
Guitar pickups are also a problem in this room as well as the spring reverb.
Quite a bit comes from ingress into the DL-103 itself.
I'm not worried about it: In this particular case you wouldn't want to monitor at a level where you could actually hear it.
If the needle were to drop or the platter start spinning the monitors would be destroyed.
I actually ran gain up in a deep fade to listen to the noise floor, couldn't hear it beneath the surface noise, and quit afraid I would run into the intro of the next cut.
I'm not going to spend any time on it right now because as a practical matter its so deep in the mud as not to matter.
I do want to get some mu-metal to quieten the spring reverb and I'll try lining the metal Hammond box with it.
Not sure I can do much to shield the DL-103.
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
First off, thanks to show all this nice work.
I am very interested about this.I do want to get some mu-metal....and I'll try lining the metal Hammond box with it.
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Wayne
What about placing the BIG TX into a 5 Gal steel paint can? This may give you another 10-20dB reduction.
What about placing the BIG TX into a 5 Gal steel paint can? This may give you another 10-20dB reduction.
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Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
I need to pickup a clean paint can.
It will fit in a 1 gallon.
I usually keep those but used the last ones for some stain.
It will fit in a 1 gallon.
I usually keep those but used the last ones for some stain.
Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
How about using a Hoffman "screw cover pull box" without the knock-outs as an outer shell? Widely available from electrical supply distributors. Heavy gauge steel.
I'm thinking about getting a decently sized one...maybe 8x8 or larger....and poking Neutrik XLR and TRS jacks into the side along with some binding posts for DC power. Then I can sit my solderless protoboards, perfboards, new PC boards inside and have some magnetic shielding.
Bri
I'm thinking about getting a decently sized one...maybe 8x8 or larger....and poking Neutrik XLR and TRS jacks into the side along with some binding posts for DC power. Then I can sit my solderless protoboards, perfboards, new PC boards inside and have some magnetic shielding.
Bri
Professional audio and video systems design/installation/maintenance.
www.BrianRoth.com
www.BrianRoth.com