I am in the process of building a 4p1L driving a GM70 amp and want to use analog ammeter and voltmeter in each of the B+(A and V), bias supply(V) and Heater PSU(A and V).
Want to place them on neg rail in between second to last PSU LC stage.
Does this effect PSU efficiency or power delivery? Does it effect sound?
Any brand suggestions for analog meters, especially for the 1kv voltmeter?
Want to place them on neg rail in between second to last PSU LC stage.
Does this effect PSU efficiency or power delivery? Does it effect sound?
Any brand suggestions for analog meters, especially for the 1kv voltmeter?
Test equipment shouldn't effect the circuit it's measuring. Here's one but it's only up to 500V.
DC 0-500V Analog Voltmeter Analogue Voltage panel meter SO45 directly Connect | eBay
DC 0-500V Analog Voltmeter Analogue Voltage panel meter SO45 directly Connect | eBay
If you're building a stereo amp, put the ammeter between the center lug of the GM70 hum pot and ground. This will let you dial in your bias voltage.
Speaking of bias voltage, use a resistor in series with a zener diode to regulate the bias voltage, then don't worry so much about the voltage meter (you need to set your bias voltage according to the ammeter anyway)
Meters for measuring voltage go across the voltage source, so that's not a concern. Ammeters do go in series, but they are very low impedance devices.
How high is your B+, and will there be a turn-on surge? A 1kV meter might not be high enough. There is one on eBay that's new Chinese production and probably worth a shot.
Panel Meter Analog DC1000V Warm Back Light Volt Voltage Voltmeter Audio Tube AMP | eBay
I've used their ammeters without any issues.
If the turn on surge is problematic, you can put a 10M resistor in series with the meter and a 1uF cap across the meter. The cap will take 10 seconds or so to charge and will protect the meter from turn on surge.
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