Hi Fi

Phil_aka_Pip

I'm happy with the fix to my EAR 834P, it sounds sweet.

The Tom Evans MicroGroove is more detailed in the treble, but it also has a background hum which I swear it didn't have when I first bought it. Could this be anything to do with the replacement smoothing caps? The originals had dried out completely. I assume Mr Repairman used the same values (he'd be unlikely to do a bodge job or gratuitously change the value of a component), so could this be a case of having to buy more expensive caps, or is it likely that there's another fault which Mr Repairman didn't notice?

And yes, I did move the external psu away from the "business box".

ecc83

I find it incredible that smoothing capacitors should have failed in any piece of gear under 20 years of age, leave alone a bit of high quality solid state gear!

I have just read up a bit on the pre amp, usual tweaky nonsense. Goes on about "super fast, super low noise" power supplies. If your active circuits are not super quiet using conventional regulators Mr Designer, maybe you need to learn about differential power supply rejection?

But enough of my rant Phil! First step, isolate the unit by plugging in screened plugs loaded with the correct termination resistance. Then record the output noise (24bits!) and have a shufty at it on Right Mark free analyser.

Dave.

Phil_aka_Pip

You're a bit ahead of me Dave. I could organise screened plugs, but what's the "correct termination resistance"? I assume the intention is to leave the inputs neither tied to ground nor open circuit so that they appear to the rest of the circuit as if a cartridge was connected, without one being connected to pick up extraneous noise? In other words a resistance that looks like a cartridge. Do cartridge suppliers state DC resistance like guitar pickup makers do? (It's a Dynavector XX1L, btw).

In the back of this PC is an M_Audio 2496 soundcard, so I assume I could (with a copy of Audacity?) capture a recording of the µGroove's o/p this way?

Sorry if that sounds thick, but like I said, you're somewhat ahead of me!

Phil_aka_Pip

I found this: www.audioaffair.co.uk/tom-evans-microgroove-plus-phono-stage and assume it's the basis of @ecc83's "rant". Just to be clear, mine isn't the "plus" model.

ecc83

Ok, sorry Phil!

The best I can find for the cartridge source resistance is 5 Ohms which is so close to buggerall that you might as well short the input plugs.

Yes, you could plug the pre amp straight into the 2496 (got 3!) but maybe the first test should be the Mk 1 Lug? Does the hum go/improve with the deck disconnected and the inputs shorted?

Dave.

Phil_aka_Pip

Will check that out soon, thanks Dave. ATM the EAR834P is wired in, but it'll be no hardship to connect the µGroove to the system in this room ....