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Eli Duttmann's phono preamp voltages
Eli Duttmann's phono preamp voltages
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Old 17th May 2019, 10:31 PM   #21
Wavebourn is offline Wavebourn  United States
Anatoliy Lisovskiy
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Eli Duttmann's phono preamp voltages
The worst ever error on the schematic, grounded rectifier before ever smoothing capacitors. Ground loop hum guaranteed, follow
attempts to eliminate it lifting grounds and buying super-duper audiophile grade cables and power conditioners.

Congratulations!
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Old 17th May 2019, 11:40 PM   #22
Eli Duttman is offline Eli Duttman  United States
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It works FINE. You are not looking at FWCT setups.
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Old 17th May 2019, 11:53 PM   #23
Wavebourn is offline Wavebourn  United States
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Eli Duttmann's phono preamp voltages
That means, the actual wiring does not follow the schematic exactly, and the drawing is deceiving. Or, you had to implement the ground lift, as I mentioned at the beginning.
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Old 18th May 2019, 12:16 AM   #24
Jeff Yourison is offline Jeff Yourison  United States
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Hi, Wavebourn,

I grounded the power supply directly at the rectifier. No hum or buzz. Any other point created a hum or buzz. In the attached photo, see the black wire originating from board just under the horizontal orange drop capacitors and going up and over to the chassis lug on the far right.
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Old 18th May 2019, 12:54 AM   #25
Wavebourn is offline Wavebourn  United States
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Eli Duttmann's phono preamp voltages
Looks like your board has pretty short trace from the rectifier to the filter capacitor, still the best point would be to ground at the negative lug of the filter capacitor.
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Old 18th May 2019, 05:15 PM   #26
gregas is offline gregas  Canada
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Default Power supply

What are your thoughts on using a switching power supply. i have a ac-dc converter and a dc to dc booster. I can use these to get the B+ voltage to run the phono preamp. I was going to try this out and see how it works. If it works well I'd keep it if not i can build a tradition power supply. Eli do you have a better resolution image of that schematic for the power supply?
Greg
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Old 18th May 2019, 05:52 PM   #27
Jeff Yourison is offline Jeff Yourison  United States
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Gregas,

Here is a pdf file of the power supply. I hope it will help.
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Old 18th May 2019, 06:17 PM   #28
Wavebourn is offline Wavebourn  United States
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Eli Duttmann's phono preamp voltages
Quote:
Originally Posted by Jeff Yourison View Post
Gregas,

Here is a pdf file of the power supply. I hope it will help.
You should draw the ground from electrolytic filter capacitors, instead of from the rectifier, to avoid pulses charging them to be applied to the signal. It may not be a problem in your particular design with very short trace between rectifier and the cap, but people following such schematics make the same error again and again.
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Old 18th May 2019, 09:13 PM   #29
leadbelly is online now leadbelly  Canada
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Sorry Wavebourn, schematics are explicitly NOT meant to convey wiring or layout information. Look it up in your favourite reference book if you don't believe me.
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Old 18th May 2019, 09:24 PM   #30
Eli Duttman is offline Eli Duttman  United States
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Quote:
What are your thoughts on using a switching power supply.
I'm not a fan of potential noise makers in audio circuitry. However, you can give it a whirl and observe what happens.

Have you given thought to a DC heater supply?
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