Apt Holman preamp: can balance Phono 1 but not Phono 2

I followed the instructions; turned the Mode control to full "L-R"; put on a mono record; used the screwdriver to adjust the pot on the side of the unit. But while it worked fine of Phono 1, on phono 2, turning the pot made no difference - there was no nulling of the sound. Any tips?


     The Apt is a great preamp.

      Out of curiosity: when was the last time the electrolytics were gone through/replaced?

      Not that those would affect the balance issue, but: the pre is somewhere around 40 years old now.

       Regarding your question: the Selector switch grounds R122, when Phono 2 is chosen, to enable it.    Try opening the chassis and cleaning it's contacts, as well as those of the R122 trimpot (Phono 2 Balance control), with some contact spray.

        Of course: you'll want to check for any possible corroded/damaged contact areas/points.    If not visible: use an Ohmmeter to test the selector for continuity* and pot, which should be variable, from 0 to 250 Ohms, IF I remember correctly (it's been a minute).

         *There shouldn't be any continuity, from the ground of R122 to chassis, until Phono 2 is chosen, via the Selector.

                                    That's all I've got.     Hope it helps!

                                                    Happy listening!



I agree - the Apt is a great preamp. Better than the younger Linn it replaced.

Had the unit recapped just after I bought it a few months back and that definitely improved the sound. 

Thanks for the tip. That's stuff I can do without being scared I'll mess it up.