I am just finishing up a tube preamp and read on another thread that a TVC can be put on the output. I hadn't thought about that but is there any advantage doing yhat?
Preamp output has definite output impedance, thus drives TVC (every 100H of TVC inductance represents about 12k5 impedance at 20Hz) -in the working frequency domain- with mostly constant driving capacity, independently of the input source device.
If you use TVC in the input side, the unknown source might cause problems at low frequencies.
If you use TVC in the input side, the unknown source might cause problems at low frequencies.
You will have much lower output impedance when you turn volume down plus other tricks due to the parallel feed.
Thanks guys....but I really don't understand that either of you said. I can build anything but not a designer.
One disadvantage is that it might not be rated for the vAC RMS at the output of the pre amp.. which will depend on the gain of your preamp and the voltage level at the output of your source.
L.H/S
L.H/S
If you use amp with average sensitivity (about 1-2V RMS for full power), the preamp gain must be about 6dB over it (2-4V). It must be below the TVC max. voltage.
Most of the -good- magnetic volume control manufacturers defined measuring/operating conditions: usually 600R source impedance, 5-8V RMS max. voltage.
See Dave Slagle's forum for more information:
intact audio
:: View Forum - Attenuators
p.s. For some years I use S&B TX-102 (400Hy) as the parafeed TVC of my CCS loaded #26 preamp.
The lover -3dB point is about 12Hz.
The other critical factor is the output interconnect capacitance. Use the possible less capacitance IC (50-200pF overall), or you have HF falling.
Most of the -good- magnetic volume control manufacturers defined measuring/operating conditions: usually 600R source impedance, 5-8V RMS max. voltage.
See Dave Slagle's forum for more information:
intact audio
:: View Forum - Attenuators
p.s. For some years I use S&B TX-102 (400Hy) as the parafeed TVC of my CCS loaded #26 preamp.
The lover -3dB point is about 12Hz.
The other critical factor is the output interconnect capacitance. Use the possible less capacitance IC (50-200pF overall), or you have HF falling.
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