In a previous thread, I expressed interest in designing my own bass preamp. All of my design goals were lined out, and more investigation revealed how similar it was to the Ampeg SVT preamp.
Well, the further I get into this the less confidence I have in my own design. I would like to get started with just cloning the SVT preamp as a learning experience and then go from there.
That being said, I am looking at the 1970's implementation, found here:
I would like to make only channel one. Instead of using V5 as a buffer, I would like to use a transformer output. The secondary will be connected to a mixer, recording device, etc. My question is, what is the output resistance of the previous stage, the cathode follower at V4?
Without the feedback I would presume it to be in the 450 ohm range. With the shown feedback, however, I'm uncertain how to find the output resistance, and thus, select the proper transformer.
I realize I could use an opamp on the output, but for now let's entertain the idea of using a transformer. Thanks for any help.
Well, the further I get into this the less confidence I have in my own design. I would like to get started with just cloning the SVT preamp as a learning experience and then go from there.
That being said, I am looking at the 1970's implementation, found here:
I would like to make only channel one. Instead of using V5 as a buffer, I would like to use a transformer output. The secondary will be connected to a mixer, recording device, etc. My question is, what is the output resistance of the previous stage, the cathode follower at V4?
Without the feedback I would presume it to be in the 450 ohm range. With the shown feedback, however, I'm uncertain how to find the output resistance, and thus, select the proper transformer.
I realize I could use an opamp on the output, but for now let's entertain the idea of using a transformer. Thanks for any help.
I'd suggest leaving V5 as a buffer, applying a low impedance load to V4 is likely to mess up the tone control circuit.
If you don't want an extra valve, use an opamp as a buffer.
If you don't want an extra valve, use an opamp as a buffer.
What about a direct box transformer? It would provide anywhere from 100K to 1M, depending on what device it's connected to.
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