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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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Bottlehead Forum Welcome! Need support, you got it. Or share you ideas and experiences. |
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In Reply to: TVC and Seduction posted by JonathanD on October 10, 2003 at 02:10:54:
Seduction was designed to feed a tube preamp, with a resistive input impedance of 50k or more. The TVC presents an inductive load to the source device, which will interact with the output coupling capacitance (0.47uF in the Seduction) and source resistance (around 5k in the Seduction). The inductance will vary with frequency and signal level, and there will be a parallel resistive component which can't be discounted. If you have some idea of these impedances, then you can evaluate the match.What TVC are you looking at? Does the manufacturer specify an appropriate source impedance and/or coupling capacitance? Or do they specify the inductance range?
To find out about the match, you must either have such specifications, or measure them yourself, or try it and find out what works.
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OK, I checked the Sowter web site. They specify a nominal impedance level of 10k, 85 henries inductance, and a source impedance of no more than 10k ohms. Seduction is 5k resistive, which is acceptable. They specify "Where necessary a blocking capacitor should be used to ensure no dc is applied to either winding" but they do not say how large the capacitor should be.
At 85 henries, ignoring any parallel resistance, a simple PSPICE model shows a 9dB peak at 26Hz. The output coupling cap is not large enough. If the inductance were always 85 henries, then a 4.7uF cap would be adequate - but I would recommend that the TVC manufacturer be consulted on this, because they will have a much better knowledge of the inductance variations. Note that a larger cap may be difficult to fit inside the Seduction, especially if the shield box is used.
Good luck! And if anyone tries this, please post results here and we'll try to work out any problems.
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Follow Ups
- Re: TVC and Seduction - Paul Joppa 10:14:42 10/11/03 (1)
- Re: TVC and Seduction - JonathanD 10:49:01 10/12/03 (0)
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