Welcome! Need support, you got it. Or share you ideas and experiences.
Just wondering whether the output is in ultralinear or pentode mode and was suprised not to see a triode output connection, would it be possible to add this feature and how?.
I try my best to answer your questions
Triode, tetrode and pentode are types of vacuum tubes. A triode is a vaccum tube with three active elements: anode, cathode and in between them a grid. The current through the valve (from anode to cathode) can be controlled by applying a varying voltage on the grid.
Pentodes (6550, EL34...) have yet another grid, the suppressor grid, inserted between the screen and the anode.
Pentodes can be connected in triode mode... i.e. they are working as a triode even though they have the extra electrodes for working as a beam pentode.
Ultra linear, push-pull, single end, parallel single end are all configurations of the circuit in which the tube works.
In UL(Ultra linear) operation, it is the screen grid which is connected to the output transformer through a separate tap. This provides local feedback because the screen voltage also controls the current through the tube to some extent. Connecting the control grid this way would cause far too much feedback. In addition there can be significant current on the screen which is captured by the UL connection to help drive the OPT. Grid currents are almost always very small. This is supposed to give lower disortion and a flatter frequency response. Ultra linear can be used push-pull or single ended.
TRK 3488 is a Class A Single Ended Ultra Liner amp. Yes, you can convert TRK-3488 to Triode mode. How?
You can refer to this link to do your experience.
Thanks for your response. I am aware on how to wire up a pentode/tetrode to a triode by connecting g2 straight to the plate or thru a resister to the plate by the hard wire method. I wanted to know how? you do this on this amplifier which uses a pc board for the signal and power supplies.
The amp's power supply section is already prewired. The PCB board is for Signal only. I can email you the circuit, but I cannot be directly involved in converting this amp to Triode mode. Theoretically, you can modify this amp to Triode mode.
The amp sounds pretty good without any further modifications.
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