worrasf
24-04-2012, 20:53
The only board in my Quad 33 that has not had a Net Audio upgrade is the disc adapter board and that's because they don't do one - yet.
The original boards are all getting on a bit and originally had a 68K impedance which is not really suited to more modern cartridges. I've changed a few resistors in previous boards to get it to a more useful 46K which was an improvement but felt it could be better. So I decided to "depopulate" an entire board and "repopulate" with up to date decent spec components - to whit Takman metal film resistors, Amtrans AMCO and polystyrene capacitors from HiFi collective.
The Quad boards all have surface mounted tracks - not the modern PCB's and these tracks are prone to lift and split. So having very carefully de-soldered each component I then used a fine rotating bur in a high speed hand piece motor to drill out each hole through the solder plug. I've found to my cost if you don't have completely clear holes on these old boards and try to pass new component legs through the plugs using a soldering iron to melt the plug the tracks tend to lift and fracture - drilling each one out is much the best way.
I also over-soldered all the edge contact tracks as over time these had worn grooves from repeatedly being taken in an to and in places had worn through to the board.
Anyway once all cleaned up the new bits went in in double quick time.
The new board sounds so much better than any of the other old ones I've used.
It's quiet with no background noise and has a "sweeter" and cleaner more "open" quality with more detail and precision.
I expect it will need a break-in period but straight "off the bench" it is night and day better than the old board - but then I guess you'd expect it to be. All for less than £50.
:cool:
Steve
The original boards are all getting on a bit and originally had a 68K impedance which is not really suited to more modern cartridges. I've changed a few resistors in previous boards to get it to a more useful 46K which was an improvement but felt it could be better. So I decided to "depopulate" an entire board and "repopulate" with up to date decent spec components - to whit Takman metal film resistors, Amtrans AMCO and polystyrene capacitors from HiFi collective.
The Quad boards all have surface mounted tracks - not the modern PCB's and these tracks are prone to lift and split. So having very carefully de-soldered each component I then used a fine rotating bur in a high speed hand piece motor to drill out each hole through the solder plug. I've found to my cost if you don't have completely clear holes on these old boards and try to pass new component legs through the plugs using a soldering iron to melt the plug the tracks tend to lift and fracture - drilling each one out is much the best way.
I also over-soldered all the edge contact tracks as over time these had worn grooves from repeatedly being taken in an to and in places had worn through to the board.
Anyway once all cleaned up the new bits went in in double quick time.
The new board sounds so much better than any of the other old ones I've used.
It's quiet with no background noise and has a "sweeter" and cleaner more "open" quality with more detail and precision.
I expect it will need a break-in period but straight "off the bench" it is night and day better than the old board - but then I guess you'd expect it to be. All for less than £50.
:cool:
Steve