Need new MC stage with good RFI suppression

Dave - if you're interested in buying used, there's a 300 hr MP500 for sale on Wigwam for £350.

Daveb975 wrote: Just to finish this thread, unfortunately the Reflex C did not solve the problem.

I had a suspicion it wouldn't. Any BJT transistor input will rectify RFI, and is the reason why I've been working on making the Accession circuit do moving coil voltages. So far in independent tests it has not picked up any interference including from Apple cellphones which tend to interfere readily with most audio circuits. The Accession uses FET inputs which are much more immune and with their virtual earth input circuitry and heavy filtering at all radio frequencies, makes it harder for interference to penetrate and upset the musical enjoyment.

Iterference is here to stay and if anything is set to worsen. Designers have to realise that no matter how good many of those existing MC preamp designs sound, they are outdated. It's something I've had to take on board and solve.

Another product which will resist interference to the same extremes is the redesigned Gram Amp 3 "Fanfare". The loaner program doesn't feature this yet, so I think it's now time to move the existing units on, and we will replace them by the latest interference resilient design.

As with all loaner program items which are superseded the existing ones are sent to people who make a charitable donation to a charity which looks after the needs of the less fortunate. If the loan co-ordinators could organise this I will ensure the "Fanfare's" get replaced.

Richardl60 wrote: Whilst not afflicted by General interference, I have suffered from loud pops from central heating switching on/off at high listening levels. I have not noticed this as much with the Accesssion as my Revelation/ Era Gold though may be something to do with the heating being used less in the warmer weather since having the accession! Will have a closer look (listen).

I believe you have the Elevator outputting to the Accession? As previously mentioned all BJT inputs no matter how they are employed are susceptible to rectification of airborne transmissions whether intentional transmissions or unintentional transmissions.

While ever the input to an amplifier circuit has no shielding airborne transmissions will be picked up and presented to the input. Turntable wiring has not changed at all since the first electric record player, which seems rather stupid when considering the proliferation of high energy transmission sources.

So if the turntable manufacturers are too ignorant (and arrogant it would seem) to do anything about it, the problem has to be tackled elsewhere. It falls to the electronics engineering designer to find ways to prevent his(her) circuits rectifying this interference. The prototype Accession MC is so far quite successful in achieving this.