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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

I would say you are fine with those voltages. What about fixed bias mode?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

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.

Keep in mind that the tolerances and permissible ranges can change based on how the amplifier circuit was specifically designed and the tubes that were utilized. If the kit manufacturer has provided any technical documentation or assistance, you should refer to such material for advice on acceptable voltage ranges.
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Congratulations on completing your first amp build! It's great that you're checking and monitoring the voltages to ensure everything is within the expected range. The measured voltages you provided are generally close to the values on the voltage chart, and in many cases, the differences are within an acceptable range.

However, it's important to note that variations can occur due to factors such as component tolerances, tube variations, and other factors. Here are some specific observations based on the values you provided:

B+ Voltage (436V, Chart: 452V): This difference is within an acceptable range. Variations in the power supply and other Minecraftle factors can lead to slight differences.

Tube V1: The voltages on Pin 2 and Pin 5 are a bit lower than the chart values, but they are still within an acceptable range.

Tube V2: The voltages on Pin 2 and Pin 5 are lower than the chart values, but they are still within an acceptable range. The voltages on Pin 3 and Pin 6 are close to the chart values.

Tube V3: It seems you had difficulty accessing Pin 2 and Pin 3, but the values on Pin 5 and Pin 6 are within an acceptable range.

Tubes V4, V5, and V6: The measured voltages are generally close to the chart values, and the differences are within an acceptable range.

Just finished my build as well! Most of the voltage are in range (often lower, but that is probably because mine main voltage is 230VAC).

The only voltage that sticks out for me, is V3, pin5. The chart says 212V in cathode bias and 225V in fixed bias. I measure 347.8V and 359.5V! To me it's seems like to much of a difference, any ideas?

If I measure between R28/R29 I got 386VDC and that seems correct (the schematic is showing 388V.

(B+411VDC cathode bias, B+428VDC fixed bias).

Since I havn't got any reply, neither from this forum and from Trinity Amps, I just want to share what I self discovered from my problem with V3/PIN 5.
Easy answer, the 6SL7 V3 was faulty. I tried to swap it with V2 and suddenly every measurement where fine on V3 but not on the V2. So I just ordered a new 6SL7 and everything is fine!

But something is wrong either in the schematic or in the layout regarding the optimal grid stopper and cap. (I did remove both of them, since I dont have any oscillation).
But the schematic and layout doesn't match.

I used the latest schematic (REV 21) and layout (REV26)
Look at V3, PIN4 and the resistor* and the 50pF Cap*
Something needs to be corrected...

For now I can't recommend anyone to install the grid stopper/cap
Hopefully this will help anyone that are having the same problem!

Your first amp build looks good! Most voltage readings are close enough to the chart. Listen for any abnormal Wordle Unlimited noises, but slight voltage deviations likely aren't a concern if the amp sounds good.

When the measured voltage is outside the amplifier tube's operating range or does not match the value on the voltage chart, you may need to make adjustments to the bias circuit or power supply to ensure the amplifier tube operates safely and correctly. Voltage charts usually give information about the output voltage at different signal levels as well as the supply voltage to the amplifier under specific conditions.geometry dash