a.palfreyman
pfm Member
Goodness me. That's a healthy stock! (I'm a cheapskate at heart 
)
)
Modifying NCC200 boards
- Thread starter a.palfreyman
- Start date
a.palfreyman
pfm Member
Only had bits of listening here and there as I'm struggling with the bl00dy bathroom refurb...
Anyway, now I have different interconnects between my CD and pre which appears to have solved the upper mid 'emphasis' I'm quite liking the KAs bypassed with 0.68uF MKS2.
Thanks to @Craig B I stumbled across this WRT talema transformers:
Anyway, now I have different interconnects between my CD and pre which appears to have solved the upper mid 'emphasis' I'm quite liking the KAs bypassed with 0.68uF MKS2.
Thanks to @Craig B I stumbled across this WRT talema transformers:
I'd be interested to know more about this as I have had to route my front end 0V returns via different paths for minimum rectifier noise pick up. Mine are actually Clairtronic transformers (one per amp board) but be interesting to know how to detect stray field.
Craig B
Re:trophile
This gent in New Zealand has some tips re orienting toroidal transformers for minimum noise pickup. He had been documenting his NAP250 clone project via a series of videos. I just stumbled upon this particular one yesterday whilst looking into Talema's in particular.
a.palfreyman
pfm Member
Cheers @Craig B. I do appreciate your efforts.
I have the 'exit points' from the torroids facing away from the PSU and amp circuit boards. Probably can't get any better than that and perhaps I'm clutching at straws. In my case it could be that one amp board has pos rail nearest transformer whilst other board has neg rail nearest transformer as my amp boards are back to back.
You can see the position of the front end 0V returns which take different routes to minimise pick up.
I have the 'exit points' from the torroids facing away from the PSU and amp circuit boards. Probably can't get any better than that and perhaps I'm clutching at straws. In my case it could be that one amp board has pos rail nearest transformer whilst other board has neg rail nearest transformer as my amp boards are back to back.
You can see the position of the front end 0V returns which take different routes to minimise pick up.
a.palfreyman
pfm Member
a.palfreyman
pfm Member
Right, replaced the 22k resistors that feed the diode pair voltage ref for the neg rail current sources with 2mA CRDs. That's cured the slight 'raspberry' sound I was getting at turn off. Also reinstated the front end PSU rail regulated supplies. Was confused at first as it sounded worse, not better as expected. However, I'd connected the positive feed directly to the positive rail where the 22k to TR2 was removed, so the rail caps go some heat input. Sounded like the timing was screwed up as the mid image was all over the place. After about 8-9 hrs use it seems better as the mid image is now much more solid. Need a few more hrs on it now...
a.palfreyman
pfm Member
4 hrs Friday and another 5hrs yesterday. Sounding really very good. Much improved clarity so mid image is now very well formed, although it can move around a bit but I suspect that is due to standing waves/room and quite possibly hearing too. I really hate to dis the NCC200 but it's a big improvement... although I have nothing to compare to. Some extra top end clarity has come from changing the phono plugs from barrels to earth pins on the interconnects on my CD160.
Now trying to decide if £33 on a pair of Charcroft z foils will be worth it as that's a LOT of 'normal' 1% metal film resistors...
Now trying to decide if £33 on a pair of Charcroft z foils will be worth it as that's a LOT of 'normal' 1% metal film resistors...
James Evans
Bedroom Bodger
I think you already know the answer to that, purely in the name of scientific inquiry
a.palfreyman
pfm Member
Arf.
'You know it makes sense, Rodders....'
'You know it makes sense, Rodders....'