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Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Boyuu EL34 A9 Tube Amp
Boyuu EL34 A9 Tube Amp
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Old Yesterday, 08:34 PM   #901
6A3sUMMER is offline 6A3sUMMER  United States
diyAudio Member
Join Date: Jun 2016

This thread has 900 posts.
There have been several schematics, not all the same.
I believe some in this thread have built their own amp, with various parts, just referring to the schematic (parts may or may not be the same).
Others purchase the kit. But I believe there are at least 2 versions of the kit.

Fdlima has one version of the Boyuu amp. Is there more than one version?
Were there any parts changes during the production run(s) of the Boyuu amp?
How about any circuit changes of the Boyuu amp?

Getting different results only takes:
One part change (self bias resistor, output transformer, tube rolling, UL tap was 40% but now is 50% etc.).
Output mode change (UL, Triode, Pentode),
Addition of negative feedback (and method: output tap to output tube cathode,
output tap to driver cathode circuit, Schade feedback, etc.).

Most of these kit amps seem to have a circuit board; but that does not stop eager builders from making major changes.

And then there are tubes, weak tubes, tube ‘substitutes’ and Bogus tubes.

Apparently, some do get low power from (some versions of) these amplifiers.

For any amplifier that is not performing as the owner expects, there are lots of specifics that need to be known by anyone that would attempt to troubleshoot it via the internet.

I do not always write clearly. I also make mistakes.
I said: “It sounds like the EL34 is triode wired.”
Of course I can not “hear” what his amp sounds like.
I should have said: “Perhaps you wired your amp in triode mode.”

My next post will address something about long threads.

Thanks to all on this forum who read, write, build, listen, and participate.
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Old Yesterday, 08:51 PM   #902
6A3sUMMER is offline 6A3sUMMER  United States
diyAudio Member
Join Date: Jun 2016
To the Moderators of this Forum:

I believe the rules state that we need to do a search before we start a new thread.
That has several advantages:
It reduces the amount of threads that come up in a search (easier to find what you want).
It allows the many contributions on a subject or device, etc. to be in one place (one thread).
I am sure many others can list other examples of advantages.

But there is another side as to whether or not to start a new thread:

Using this thread as an example (unless someone else puts up a post before I finish my edits,
this will be post # 902).

My post 901 shows that unless you read through all the previous 900 posts, you may miss something.
We do not all have the time to read through 900, and analyze each post, and then give
help based on all of that to a new (late) “poster” who is having problems.
And did that new poster read through all 900 posts so that we are all on the same page, so to speak.

And a late post may refer to a schematic, but which one?
And is there a modification that is not in the schematic?

Starting with a new thread might make the person who starts that thread to be careful to
give details, so we can start from there; instead of starting with some assumptions about
posts 400 to 450 that similarly address the problem.

No, I do not really propose making it easier to start a new thread, but I am sure some get frustrated by not having a new one on a clean slate.

Does anybody have a solution?
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Old Yesterday, 10:49 PM   #903
VictoriaGuy is offline VictoriaGuy  Canada
diyAudio Member
Join Date: Dec 2008
Location: Victoria, BC
Boyuu EL34 A9 Tube Amp
Wow...I was just trying to help by posting the stock schematic.

Fdlima joined the thread at Post #768 so it is a while back, I admit.

"Have a good day."
Richard Feynman: "The first principle is that you must not fool yourself and you are the easiest person to fool."
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