What is the goal here? Are we trying to reduce the gain of this amp and figure out why it's crunching from the output of the 834P clone preamp?
Or am I missing something?
Yes, the goal is to stop the crunch from the 834, but as I haven't been able to recreate that crunch when getting audio signal from any other source, I'm realizing the problem may lie with the 834, not the amp.
I'm also eager to learn more about tube amp design, wondering if I have this driver tube set at the ideal operating point, trying to figure out how to get that information from the tube charts, etc etc.
I'm also eager to learn more about tube amp design, wondering if I have this driver tube set at the ideal operating point, trying to figure out how to get that information from the tube charts, etc etc.
Basic troubleshooting:
- Swap devices to see if the problem follows the individual device, or if the problem is always present no matter which device you connect.
So for instance, if you have a bad noise happening in the left channel of a stereo tube preamp that uses only one tube per channel, you can swap the tubes between left and right channels to test.
1) If the problem 'follows the tube' then you know the tube is the problem (solution = replace the tube with a new one).
2) If the problem stays in the left channel then you know the tubes are not the problem, but that there is something about the left channel circuitry in the preamp that has a problem.
Again, what is the goal here? What are you defining as "the ideal operating point"? What does "ideal" mean to you? Is there even an ideal operating point at all? (Actually, there is only the best compromise between this and that. There is no true 'ideal'. My opinion, of course.)
Step 1) Define your goals. (Low distortion? Quiet operation? Full power from the amp at volume control set at 75% up? ???)
Step 2) Figure out what you need to do in order to attain those goals.
Step 3) Do it.
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As for learning more about tube amp design, I really like MerlinB's book "Designing High Fidelity Tube Preamps". My opinion only, but I think Merlin writes in an easy to comprehend way but still provides enough data and theory to give you a well-rounded understanding -- as long as you're willing to work out the equations and situational problems he presents.
The other highly regarded book on tube amp design is Morgan Jones' "Valve Amplifiers - 4th Edition". This book goes more into power amp design, with an analysis of a few classic amp designs, and a few examples of his original designs that would make good projects for building.
Without some basic technical understanding, it's going to be difficult to come up with reasonably well optimized designs. Even with some understanding, there are lots of contradictory problems to solve that make it impossible to arrive at an 'ideal' design, and often difficult to arrive at even a 'good enough' design. The journey can be a lot of fun though.
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Oh, and if you'd rather read free stuff on the internet first, check out MerlinB's Valve Wizard site (more oriented towards tube guitar amp design, but the basic concepts are the same). There's lots of great info there.
There's also John Broskie's TubeCad Journal site, but he's writing for a more advanced audience, I think. If you search for a particular topic you want to learn about, you can often find a good discussion on Broskie's site.
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The other highly regarded book on tube amp design is Morgan Jones' "Valve Amplifiers - 4th Edition". This book goes more into power amp design, with an analysis of a few classic amp designs, and a few examples of his original designs that would make good projects for building.
Without some basic technical understanding, it's going to be difficult to come up with reasonably well optimized designs. Even with some understanding, there are lots of contradictory problems to solve that make it impossible to arrive at an 'ideal' design, and often difficult to arrive at even a 'good enough' design. The journey can be a lot of fun though.
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Oh, and if you'd rather read free stuff on the internet first, check out MerlinB's Valve Wizard site (more oriented towards tube guitar amp design, but the basic concepts are the same). There's lots of great info there.
There's also John Broskie's TubeCad Journal site, but he's writing for a more advanced audience, I think. If you search for a particular topic you want to learn about, you can often find a good discussion on Broskie's site.
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