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the volume control

Posted by Ralph (M) on October 28, 2015 at 09:23:25

In Reply to: THAT.... posted by Lew on October 27, 2015 at 21:44:16:

-was replaced by a Shallco part similar to what you see in the photo with the introduction of the MkII (about 1997).

I'm guessing you must have a Mk1 to be asking that question (I know your preamp is modified but it must have started life as a Mk1).

Both controls are built along the same lines; the Mk1 employed a custom Electro-Switch part (similar to what you see in a Convergent preamp, but more decks). The Shallco part of the MkII and later sounds a little better purely on account of its construction.

With the Mk3.1, the taper of the control was changed to reduce Miller effects mid-band in the control and to make the use of digital products easier. The Mk3.2 took this a step further; in the Mk3.3 the Gain Trim controls were changed to a shunt-style system making them secondary volume controls in their own right so now you can set up the gain structure however you want.

This was important because in the Mk3.3 the phono gain is so much higher that with most LOMC cartridges the output is about the same as you see from digital sources. If you had speakers with more than about 95 db 1 watt/1 meter or an amplifier with over 30db of gain, you might have had troubles with the main control not having enough notches at the bottom end of its range. With the Gain Trim system thus updated this problem is eliminated without a down side.

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