TVA-1 cathode resistor value

audiohead · 9th December 2007, 07:06 PM

I just simulated Michaelson & Auatin TVA-1 driver stage. The value of 2nd stage (12AT7) cathode resistor as shown (33K) cannot be correct.

I used 3k3 instead. Is the schematic in error?

Art

ichiban · 9th December 2007, 07:43 PM

The schematic I have, which is from an owner of a TVA-1,
shows the resistor value at 2k2R. At the bottom is a note
stating that the "Latest TVA-1 has 47R in cathode". I don't
know which cathode the note refers to!? Possibly the output
tubes, in place of the 100R's.
The owner of the TVA-1 used it to power the base panels
of a Magnapan Tympani D-1 crossed over, with a Waldron
tube 3rd order xvr at 1000 cycles for the lowpass and a
simple 6dB cap filter to a Marantz 8B for the highpass.
The bass of the TVA-1 was awsome with GoldLion KT-88s.

Herrmann · 9th December 2007, 08:04 PM

Hi
On my schematic the cathode resistor has the value 2k2.
Torben

audiohead · 9th December 2007, 08:15 PM

The schematic I used is available on line. Thanks for the response though, 33K is defintely wrong value, 3k3 cathode resistor results in 3.2 mA of tail current , 2k2 is around 4 mA.

The step network (4.7Meg in shunt with 0.022, in series with 470k) is pretty much useless, since the plate voltage of 12AX7 is only 25V.

Art

9th December 2007, 07:06 PM	#1
audiohead diyAudio Member Join Date: Mar 2005 Location: Los Angeles, california	TVA-1 cathode resistor value I just simulated Michaelson & Auatin TVA-1 driver stage. The value of 2nd stage (12AT7) cathode resistor as shown (33K) cannot be correct. I used 3k3 instead. Is the schematic in error? Art

9th December 2007, 07:43 PM	#2
ichiban space charged diyAudio Member Join Date: Oct 2004 Location: WNY	12AT7 cathode resistor The schematic I have, which is from an owner of a TVA-1, shows the resistor value at 2k2R. At the bottom is a note stating that the "Latest TVA-1 has 47R in cathode". I don't know which cathode the note refers to!? Possibly the output tubes, in place of the 100R's. The owner of the TVA-1 used it to power the base panels of a Magnapan Tympani D-1 crossed over, with a Waldron tube 3rd order xvr at 1000 cycles for the lowpass and a simple 6dB cap filter to a Marantz 8B for the highpass. The bass of the TVA-1 was awsome with GoldLion KT-88s.

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9th December 2007, 08:04 PM	#3
Herrmann diyAudio Member Join Date: Feb 2002 Location: Denmark	Hi On my schematic the cathode resistor has the value 2k2. Torben

9th December 2007, 08:15 PM	#4
audiohead diyAudio Member Join Date: Mar 2005 Location: Los Angeles, california	The schematic I used is available on line. Thanks for the response though, 33K is defintely wrong value, 3k3 cathode resistor results in 3.2 mA of tail current , 2k2 is around 4 mA. The step network (4.7Meg in shunt with 0.022, in series with 470k) is pretty much useless, since the plate voltage of 12AX7 is only 25V. Art

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