I would try a "brute force" method like Miller caps for the tubes, or shunts on the grids, or frequency compensated nested feedback. Or, a faster op amp might work.
33.9 kHz is entirely too low. This will start rolling off at 3.4 kHz!
I shoot for 159 kHz minimum (easy to achieve with common part values ) which is down 0.1 dB @ 15.9 kHz, close enough and easy to bump up to 200 kHz + with a simple parts swap if necessary.
Depending on how much gain you need, you might try a buffer like the LME49600 or BUF634. All your gain will be from the triode and the buffers are fast enough to keep you out of trouble. Of course you'll need to reconfigure your input for gain. I haven't investigated this circuit but it seems simpler than what you're trying to do. I bet it would make a good headphone amp.
Those Tubecad circuits aren't all turnkey circuits. Some are concepts that must be sorted out (like this one). There are a lot of cool ideas on that website though. Circuits like the ones on the ESP site are more like turnkey circuits that can be built without engineering skills.
33.9 kHz is entirely too low. This will start rolling off at 3.4 kHz!
I shoot for 159 kHz minimum (easy to achieve with common part values ) which is down 0.1 dB @ 15.9 kHz, close enough and easy to bump up to 200 kHz + with a simple parts swap if necessary.Depending on how much gain you need, you might try a buffer like the LME49600 or BUF634. All your gain will be from the triode and the buffers are fast enough to keep you out of trouble. Of course you'll need to reconfigure your input for gain. I haven't investigated this circuit but it seems simpler than what you're trying to do. I bet it would make a good headphone amp.
Those Tubecad circuits aren't all turnkey circuits. Some are concepts that must be sorted out (like this one). There are a lot of cool ideas on that website though. Circuits like the ones on the ESP site are more like turnkey circuits that can be built without engineering skills.
Okay, i tried the compensation suggestion and it still didn't make any sound. Touching my fingers on the input didn't make a buzz anymore. I believe the TDA7265 is dead. The speaker only made a short click each time i turn on the bipolar power supply to the chip.
Looks like a total re-do is in order. I happen to have a pair of LM1875. I will redesign the pcb. Good news that LM1875 needs only 10x gain to be stable.
Will post the design here for input before i send it to the PCB fabricator.
Looks like a total re-do is in order. I happen to have a pair of LM1875. I will redesign the pcb. Good news that LM1875 needs only 10x gain to be stable.
Will post the design here for input before i send it to the PCB fabricator.
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