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PostPosted: Sun Jan 22, 2023 8:11 am 

Joined: Sun Jan 22, 2023 7:08 am
Posts: 1
Hi all

Just finished building a Trip Top kit (my first amp build!) and wanted to check how close the measured voltages should be to the Voltage Charts? Supply voltage is 240V and I am using 6L6GC's. I am using JJ Tubes for all tubes.

Below is what I am reading in Cathode Bias (figure in brackets is the Voltage Chart value)
B+ 436V (452)
V1 Pin2 167.8 (178) Pin3 2.42 (2.3) Pin5 171.8 (190.0) Pin6 2.0 (1.9)
V2 Pin2 93.2 (114) Pin3 1.32 (1.2) Pin 5171.3 (183.0 Pin6 2.38 (2.2)
V3 Pin2 (difficulty getting to access) Pin 3 (Difficulty getting access) Pin5 177 (212) Pin6 1.88 (2.2)
V4 Pin3 433 (449) Pin4 427 (427) Pin8 35.2 (32)
V5 Pin3 436 (449) Pin4 428 (427) Pin8 35.2 (32)
V6 Pin4 356 (364) Pin6 355(364)

Thanks in advance for your assistance. Cheers Andrew

PostPosted: Wed Mar 01, 2023 4:02 pm 
Holy Ghost
Holy Ghost
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Joined: Sun Mar 13, 2005 4:10 pm
Posts: 7519
Location: Canada
I would say you are fine with those voltages. What about fixed bias mode?

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PostPosted: Wed Aug 09, 2023 10:35 pm 

Joined: Mon May 08, 2023 5:23 am
Posts: 7
Hello Andrew,

Congratulations on building your first amp kit! It sounds like you've made good progress. When it comes to measuring voltages in a tube amplifier circuit, there can be some variation from the ideal values due to factors such as component tolerances, tube characteristics, and other variables. However, it's important to ensure that the measured voltages are within a reasonable range to ensure the proper operation and safety of the amplifier.

Looking at the voltages you've provided, here are a few observations:

B+ Voltage (436V): The difference between your measured B+ voltage (436V) and the chart value (452V) isn't significant. It's common for supply voltage to vary a bit, and as long as it's within a reasonable range, it should be fine.

Voltage on Tube Pins: For most of the pins you've listed, the differences between the measured values and the chart values are within an acceptable range. Tubes and components can have variations, and small deviations from the ideal values are normal.

V3 Voltage (Pin5): The difference on V3 Pin5 (177V vs. 212V) is a bit larger than the others. If this voltage is intended for a cathode resistor bias, a significant difference could impact the biasing and overall performance of the tube. You might want to investigate this further, especially if there's difficulty accessing the pins. only up

V4, V5, and V6: The measured voltages on these pins seem reasonably close to the chart values, with small variations that are likely within the normal range.

Remember that the tolerances and acceptable ranges can vary depending on the specific design of the amplifier circuit and the tubes being used. If you have access to any technical documentation or support from the kit manufacturer, it's a good idea to consult that information for guidance on acceptable voltage ranges.

If you're concerned about any specific measurements, it might be a good idea to consult with experienced amp builders or technicians who can provide more precise advice based on the details of the circuit you're working with. Always prioritize safety when working with high voltages and complex electronics.

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