Phono Stage Fiddlings

Although I have a Stageline in the system at the moment, I started wondering if I couldn't achieve the same or better result from powering the normal phono boards separately, so I've embarked on a (hopefully) series of trials.

The boards I'm using are a pair of 323/3 S boards, so not the latest and greatest, but not worth much, so no loss if things don't work out.

I've spent some time tracing the circuit round the card, and have created an interactive walk round the circuit (sort of).

Stage One

Right, here I've simply plopped the boards into a box and wired them up. The connections to the board from left to right are:

Pin 1 - signal in
Pin 2 - 0v
Pin 3 - signal out
Pin 4 - power in (24v)

Things to watch out for - removing the push on connectors is a bit of a pig if you want to save them - you'll need to remove as much solder as possible, and hope.
I drilled holes in the PCB to allow me to use the plastic PCB supports with sticky base to fix to the box - you need to be REALLY careful if you do this, as there's not much space, and it would be easy to either partially or totally cut a PCB track.

How does it sound?
Well, I'm really impressed with this. It's been a while since I had the cards in the 32.5 in "standard" configuration, as the Stageline was such an upgrade from them. But now these self same cards have their own power supply, then there is VERY little difference between Stage One and the Stageline. I listened to Stage One first, and on moving over the the Stageline, I though it sounded a bit more "relaxed" and open, but reverting to Stage One I honestly couldn't really tell the difference. Result!

The stock 323/3 s phono board - 11 Oct 2003

Here´s the board in standard form - only change is the removal of the connectors, and the hardwiring of the cables.

OK, this is basically just a pair if Naim 323/3 S boards, with the push on connectors removed, fixed into a cheap box, and the relevant cabling attached.

Stage Two

First set of alterations. Here, I have just removed the three polyester capacitors - C5 (68nF), C6 (22nF) and C9 (6n8F). The two smaller values were replaced with polystyrene components, and the 68nF with a PPS capacitor (polystyrene being hard to find in this size - certainly that would fit on the board!

Note with C9 there is an extra hole in the PCB (well, there was in mine - in the picture above of the "straight" board, it's just below the "M" of the initials "GM") in the centre of the 0v area, which is just in the right position for the replacement capacitor. With C6 you will probably have to bend the leads round to fit it in place - it's a bit of a squeeze.

The PPS I used also needed its legs bent inwards slightly (5mm board pitch, 7.5mm pitch on the new cap). Not too bad though.

Components used
C5 -
C6 -
C9 -

How Does it Sound?
A small step forwards - more control to the bass, as well more tune. Cymbals seem to have more "ring" to them, and the individual characteristics of each one is more obvious.

First mods to the 323/3 s board - 25 Oct 2003

Here´s the phono board after the first set of changes - swapping out the three polyester capacitors (the shiny "block" like ones).

Stage Three

Next on the agenda is changing some more capacitors - C1 and C7 - the 10uF red "beads", and C4 and C8 - the dark red 47uF electrolytics.
I changed the 47uF electrolytics to some 56uF Sanyo Oscons from the SP series. The beads have been replaced with 10uF BC128 (2222). I'm going to try these for a bit then swap them for some 10uF Oscons, and see how they differ.

Components used
C1, C7 -
C4, C8 -

How Does it Sound?
Big jump forwards. Returning to the standard Stageline (all the same cabling, remember), the sound seemed to collapse down between the speakers, whereas with the modded cards, the sound is really "out of the box" now. The Oscons take some time to bed in, I understand, so I'm leaving things as they are for a while to see what happens next!