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Did You Upgrade the Phono EQ for the Highs in the M65 ?







Not to downgrade the Advent 300 phono stage, or rob the post, but tube phono preamps are the preference to many of us. I have an Advent around, but rarely use it. By itself, the Advent can sound great. The tuner is a bit harsh sounding. Connecting an upgraded tube phono stage, like an M65 into the Aux jacks will probably convince most that tubes rule...

Shure purposely built-in a high frequency peak of +3 db at 10KHz in this Phono Conversion Preamp unit. Developed in the early '60s, Shure's M3D, M7D and M33D cartridges available at that time, were a bit reticent in the upper highs, compared to later Shure carts and many magnetics. That peaking network, with 100K across 420 pf, should have about 680-750 pf for flatter RIAA EQ. The stock M65 bass EQ is ballsy; very pleasant. The quickest fix would be simply adding 250-330 pf across the 420 pf caps inside; yielding 680-750 pf across 100K. Even better, use polystyrene caps instead of the stock ceramic EQ caps. Polystyrenes are superior to mica as well, in this circuit. Be prepared to let the new poly caps break-in for over 20 hours of listening. You might want to upgrade the four coupling caps also. Short out that ridiculous input ceramic cap with wire; as it's not needed. Upgrade the power supply capacitance to a few hundred uf, and the M65 is very hard to beat.

In my photo, there are two M65s uncovered. Note that one still has it's original coupling caps. Those of us that have the white coupling caps inside their M65s need to replace them. Also uncovered is the chrome stereo phono pre available from Japan. This little cutie needs even more phono EQ upgrading and wiring needed in it's tight quarters; but when done, I can use this with two turntables !


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  Michael Percy Audio  


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