Accession for Moving Coil

Aussie Mick wrote: Too late! I've ordered an Elevator EXP and I'm positive I'm going to be a very happy camper. Mick.

Of course you are!

Nearly two months on and the early adopters of the AccMC seem quite happy with them, and John C received glowing praise from one customer...

...but it was not my kind of music reproduction.

Since then I posted Understanding Record Repro, and uncovered the sheer level of interference on the cartridge wiring and took photos of the scope displays as evidence.

The level of interference was same for MM and MC, busting the myth that MC is largely immune to that sort of thing because of its low inductance.

My conclusion was the character of the sound was being influenced by the interference, which is relatively 10 times what it is using MM. And with MM I don't get the same characteristic.

I played around with many kinds of filters to no avail, and I eventually had to conclude that the level of interference was somehow mixing with harmonic distortion at really high frequencies, and by a process known as heterodyning, was making different audible sounds to what my ears expected.

I decided to try and 'kill' the highs by making a pre-preamp or head amp stage to preceed the MM version of the Accession. Making the head amp such that its high frequency performance isn't manipulated like op-amps do. I found that the modern ADA4627 and the ageing NE5534 shared  slew rate enhancement, which basically made matters worse, so it needed something which would do high frequencies 'naturally'.

Having made (or cloned) just about every idea ever imagined by all kinds of audio electronics professionals, I knew that going there again would be fruitless.

So I simply took one low noise transistor - a medium power device often used as pre-driver in power amplifiers - and made a simple single transistor pre-preamp out of it.

The result? Incredibly better! How does it measure? Almost just as good!

The prototype of this has been running now for just over a week, and so far the sound - the sound I can live with that is - has not took a turn for the worse.

It might now be the time to un-abandon it.

Good news indeed, soon we might all be able to hear how an MC really sounds.