Building myself a tube phonoamp, and I have some questions about earthing/grounding. In phonoamps we have the grounding screw close by where the phono chassie socket are, were the plugs from the TT are connected.
I wonder if this earth/gound point must be isolated from the chassie?
Se my bad drawing...And thanks for a great forum!
I wonder if this earth/gound point must be isolated from the chassie?
Se my bad drawing...And thanks for a great forum!
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It looks like you have the signal ground lifted from chassis ground with the 150 ohm resistor? You should have for safety 2 high current diodes in parallel with that resistor and cap, one in each orientation. To answer your question, yes grounding post direct to the chassis, and not connected to the separate circuit ground. I did something similar and added RF shunting caps from each RCA input common to chassis, I think it was 0.01uF maybe.
The mains earth should be bonded to the metal chassis and then use that point to connect the signal ground to earth through your resistor. No need for the capacitor, in my experience, is does nothing useful.
If your turntable has an 'earth' lead, it goes to the phono amp ground.
You might want to try an better earth lift idea. A 5 Amp bridge rectifier and 10 ohm 5 watt resistor.
See: Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
You might want to try an better earth lift idea. A 5 Amp bridge rectifier and 10 ohm 5 watt resistor.
See: Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
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Yes, what Alan said is how I do it. The link to the ESP page describes it well. The bridge rectifier makes assembling easy, the resistor and cap can be mounted on the rectifier pins, and it's all mounted with a single bolt, which can be used for the chassis grounding (wall power safety ground should be separate.)
The purpose of the cap is to shunt any RF garbage to chassis. It's effect may or may not be noticeable on its own, but I've found RF mitigation to be worthwhile in general, and this particular use of the cap is pretty standard in this application.
The purpose of the cap is to shunt any RF garbage to chassis. It's effect may or may not be noticeable on its own, but I've found RF mitigation to be worthwhile in general, and this particular use of the cap is pretty standard in this application.
Oppps, a typo.
That should read, ''A 35 Amp bridge rectifier and 10 ohm 5 watt resistor''. (The diagram is correctly marked.)