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Thanks for the input.

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

Yes, thank you all for the input. I am going to leave the amp the way it is for now as it sounds spectacular. If I do decide to change anything I'll report back. Thank you Stephen for your documentation of a great sounding circuit, I am very pleased with the result. Now on to building a head and speaker cab. I'll post photos when it's all done, could be a few months at my usual pace.

Hey guys! I'm new to the forum and have just finished a tc 15 for a friend.

I wanted to revive this thread because I'm having a hard time finding info on the forum for having B+ that is way above expected.

The main reason I'm reviving this one is that it looks to me like anode current was calculated incorrectly? I'm getting very similar voltages, but the OP calculated his current as:

8.35V/128r=.033

through the cathode resistor, I can't get that to sum the same way. I get 8.35/128=0.065

with 376v on the plate (relative to cathode) that amounts to 24.4 watts of dissipation, more than twice the max right?

am I missing something?
are people just expecting these higher voltages now?
seems like it's around 100v higher than the marked voltages on the layout.
thanks for any input!

waaaaaaaiiiit, I'm an idiot I forgot that I was calculating for TWO tubes!

In that case It looks like about 12 watts each....

I guess my question about the higher voltages being common/the way things are with the tc15 these days still stands though

Yes, the voltages are higher in the TC 15 but 376v seems a bit much, even though the dissipation is under control. You could use a 150 ohm on the cathode to cool it down; or drop the B+ voltage with a Zener Dumper
I expect the mains voltage was high as well. Can you measure that?

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

376V is indeed too high - especially relative to cathode. I would suggest trying to knock 30V or 40V off that to get the EL84s running in their sweet spot. However, the problem may be related to excessively high incoming AC wall voltage. As a check, what is your heater voltage? It needs to be under 7V AC. Then of course, you should mention the AC voltage coming in from your AC wall socket.

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Great tones come in small glass jars!

Hey all, OP back. It's been a while and unfortunately I don't have much to report back in regards to my amp build being over voltage. I have ordered several 9V zeners and intend to drop the B+ as suggested by Zaphod. Camnicklaus, are you using a Sovtek rectifier in your build? I am suspecting that it may be more efficient than the Chinese 5ar4, I would like to try swapping this out possibly before trying the zeners. Have any of you had experience with different manufacturer's rectifiers giving different voltages? If so, what tube should I go with, just the Shuguang?

B

W like the Chinese 5ar4 actually (rare) more than the JJ for example.. Pretty equivalent results. Not tried the Sovtek 5ar4.

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

This weekend I finally picked up a Chinese 5ar4 to test in my tc15. I was hoping that it might give me a different rectified voltage than the sovtek I've been using. Turns out it did... But in the wrong direction! My b+ voltage was 395 with the sovtek and shot up to 420 with the Chinese. So if you ever wondered, there it is.

This weekend I finally picked up a Chinese 5ar4 to test in my tc15. I was hoping that it might give me a different rectified voltage than the sovtek I've been using. Turns out it did... But in the wrong direction! My b+ voltage was 395 with the sovtek and shot up to 420 with the Chinese. So if you ever wondered, there it is.

Interesting. You might want to consider the Voltage Dumper along with your Sovtek. Boy, where do the tolerances go?? Out the window..

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