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Hi,

The output impedance of the TX-102 is the source's output Impedance plus around 400 Ohm and then divided by the square of the attenuation (as pure voltage ratio, not as db).

To illustrate, my Phono Stage has an output impedance of around 1KOhm. If I attenuate the signal by 12db (normal in my system) or a ratio of 4:1 the actual output impedance after the TVC is:

(1000+400) / 4 * 4 or 1400/16 or around 100 Ohm. Any more attenuation and the output impedance starts to approximate 0 Ohm ever more closely.

Conversely, the TVC's input impedance is again the load impedance transformed, if I use my 3D Sonics "Foundation" monoblocks I have a 20KOhm balanced input impedance, which is in effect multiplied by a factor of 16 to around 320K load on the source if 12db attenuation is selected.

Again, as attenuation increases the input impedance of the TX-102 quickly approaches infinity in parallel to around 600 Henry inductance and around 100pF which limits the practical input impedance to 75KOhm @ 20Hz & 20KHz and around 1100KOhm @ 1KHz.

The minimum "look-up" factor is around 10, but it should include the capacitive part of the input impedance, which is often not specified.

The S&B TX-102 initial design was derived from a 10K:10K line transformer, in other words it is designed for a load of 10KOhm or greater.

Ciao T

<blockquote data-quote="3DSonics" data-source="post: 652764" data-attributes="member: 1907">Hi,The output impedance of the TX-102 is the source's output Impedance plus around 400 Ohm and then divided by the square of the attenuation (as pure voltage ratio, not as db).To illustrate, my Phono Stage has an output impedance of around 1KOhm. If I attenuate the signal by 12db (normal in my system) or a ratio of 4:1 the actual output impedance after the TVC is:(1000+400) / 4 * 4 or 1400/16 or around 100 Ohm. Any more attenuation and the output impedance starts to approximate 0 Ohm ever more closely.Conversely, the TVC's input impedance is again the load impedance transformed, if I use my 3D Sonics &quot;Foundation&quot; monoblocks I have a 20KOhm balanced input impedance, which is in effect multiplied by a factor of 16 to around 320K load on the source if 12db attenuation is selected. Again, as attenuation increases the input impedance of the TX-102 quickly approaches infinity in parallel to around 600 Henry inductance and around 100pF which limits the practical input impedance to 75KOhm @ 20Hz &amp; 20KHz and around 1100KOhm @ 1KHz.The minimum &quot;look-up&quot; factor is around 10, but it should include the capacitive part of the input impedance, which is often not specified.The S&amp;B TX-102 initial design was derived from a 10K:10K line transformer, in other words it is designed for a load of 10KOhm or greater.Ciao T</blockquote>

[QUOTE="3DSonics, post: 652764, member: 1907"] Hi, The output impedance of the TX-102 is the source's output Impedance plus around 400 Ohm and then divided by the square of the attenuation (as pure voltage ratio, not as db). To illustrate, my Phono Stage has an output impedance of around 1KOhm. If I attenuate the signal by 12db (normal in my system) or a ratio of 4:1 the actual output impedance after the TVC is: (1000+400) / 4 * 4 or 1400/16 or around 100 Ohm. Any more attenuation and the output impedance starts to approximate 0 Ohm ever more closely. Conversely, the TVC's input impedance is again the load impedance transformed, if I use my 3D Sonics "Foundation" monoblocks I have a 20KOhm balanced input impedance, which is in effect multiplied by a factor of 16 to around 320K load on the source if 12db attenuation is selected. Again, as attenuation increases the input impedance of the TX-102 quickly approaches infinity in parallel to around 600 Henry inductance and around 100pF which limits the practical input impedance to 75KOhm @ 20Hz & 20KHz and around 1100KOhm @ 1KHz. The minimum "look-up" factor is around 10, but it should include the capacitive part of the input impedance, which is often not specified. The S&B TX-102 initial design was derived from a 10K:10K line transformer, in other words it is designed for a load of 10KOhm or greater. Ciao T [/QUOTE]

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