Thomo said:
I think they're checking out the people who've ordered samples. They want to come round to my house and help me build my dac! Which is nice of them, but I've had to put it on hold due to a lack of funds
Lee.
They are coming round in long black coats, dark sunglasses & a silenced gun in the inside pocket.
Brent
Malefoda said:
Yes. In my case I still used the original transformer.
I regulated down to +/- 7V so the LM317/337 still had enough dropout voltage and the servo amps still had enough headroom.
The gains were great. Bass was much more controlled and tight.
I don't know if it's because the servos themselves were benefitting from a regulated supply, or because it was isolating the +10V feeding the other 5V regs from servo-generated noise.
Andy Weekes once showed plots on here of nasty low-frequency servo currents causing noise peaks on the 5V rail when you press play.
If you have already added separate transformers feeding everything, then the gains from adding servo amp regulation may be small as you don't have the problem of the noise getting into other parts of the player.
It just depends upon which aspect of it made the improvement.... but I'd be very surprised if there was no improvement at all.
I originally fitted 6 7809 regs and there was improvement. Fitting 6 SPowers brought more improvement, the current delivery was improved (one fuses were bypassed). Timing became better + disc tracking improved.
It is also good to replace the +10V smoother cap with a much larger uF one.
Brent
It is also good to replace the +10V smoother cap with a much larger uF one.
Brent
Hi guys,
do you advise me to go lower than 9.7V or is it OK? I also wonder if I need a cap after each reg, in your cases you just inserted a 78/7909 or also find a place for a big cap ? As I'll insert the regs directly @U234 /237 maybe the 100/25 ZLH at each ICs are enough?
Well as I want it settle for ever I want to do it as right as possible.
Thanks,
Matthieu
(The 317/337 9.7V are the strange shaped ones, meant to be inserted in the PCB)
do you advise me to go lower than 9.7V or is it OK? I also wonder if I need a cap after each reg, in your cases you just inserted a 78/7909 or also find a place for a big cap ? As I'll insert the regs directly @U234 /237 maybe the 100/25 ZLH at each ICs are enough?
Well as I want it settle for ever I want to do it as right as possible.
Thanks,
Matthieu
(The 317/337 9.7V are the strange shaped ones, meant to be inserted in the PCB)
An externally hosted image should be here but it was not working when we last tested it.
Malefoda said:
I wouldn't go any lower than 7V, but higher is OK.
It depends what your input is under load (when playing).
It needs to be 2.5V - 3V higher than regulator voltage to regulate properly. This difference is the 'dropout' voltage.
If the dropout is below 2.5-3V it won't regulate properly but if you go much higher than this your regulators will get very hot. You should use little clip-on heatsinks anyway. (*EDIT* - assuming normal regs not LDO ones.)
That's why I set mine to 7V as there is 10V supplied from the TX.
You need the output capacitors for stability I'm afraid.
I took this photo before I put the heatsinks on.
Attachments
Malefoda said:
Yes it is a shame. You get could some of these giant capacitors that Brent uses in his PM-66KI.
http://farm4.static.flickr.com/3273/2729275006_0ce5c75ff0.jpg?v=0