It wont get any better as the sapphire is not for IEMS. It took me a while to remove the hum from the sensitive 32 ohm headphones but on my Leá IEM the hum is there. To reduce it you will need to use CRC filter infront of the sapphire, shielded cables, zobel on the rca to ground and a simple output filter.
For those who need it, I still have a pcb set
https://www.diyaudio.com/community/threads/a-pair-of-sapphire-headamp-pcb.420693/latest
https://www.diyaudio.com/community/threads/a-pair-of-sapphire-headamp-pcb.420693/latest
I've fed the Hfe of the BC327 & BC337 into a spreadsheet. I'll make it sort the 400(total) transistors by Hfe and see if I can't get closer matches between NPN - PNP within as small a percentage as possible. I think that will be better than having perfect matches within NPN and PNP, but not between them. We'll see how it turns out.
Got the Hfe gap between NPN and PNP smaller, while still keeping the match within each, NPN and PNP, at 1%.
Need to clean the lens, but here are some pics of the finished boards. All that's left to do is clean the boards with IPA, put them in an enclosure and wire everything up 🙂
Need to clean the lens, but here are some pics of the finished boards. All that's left to do is clean the boards with IPA, put them in an enclosure and wire everything up 🙂
Attachments
For the rectification part of the supply voltage, put two capacitors and a resistance, CRC... or more. 😉
It was mentioned above.
You make a small pcb for it.
If you have the possibility to do it with press&peel or another method, I will design one for you.
It was mentioned above.
You make a small pcb for it.
If you have the possibility to do it with press&peel or another method, I will design one for you.
Yes.
Sapphire is a bit sensitive to external factors and what else is found on the 230VAC network.
Sapphire is a bit sensitive to external factors and what else is found on the 230VAC network.
Ahh, now I understand. Toner transfer method is what I use the few times I make a PCB at home 🙂
That EMI filter wont do much as its way over rated in current. With EMI filters you wanna dial in the correct amperage for proper filtering. Even with my de-noiser psu which have around 100dB of 50Hz reduction i couldn't eliminate the psu hum no matter how hard i tried.
Mind you i use an unshielded plastic case with a CAT5E as umbilical power cable running across the pcs power plugs combining both digital and analog psu.
Currently i have to re-make the pcb for the Delta relay section as JLC messed up the ground plane vias again. This took me the longest to track down without a scope.
Ok, I'll use the filter you posted above, just to be on the safe side.
My build will be in a metal enclosure with the transformers in the same enclosure.
Give me a list of components... bridge rectifier and the capacitors you want to use. And the transformer data. Separate secondary or with median outlet in the secondary.
I had a thought. Is possible to point to point solder this? As far as components, I'll have to check what I have... both TH and SMD. For example, I don't think I have any inductor with that low value... but I'd have to go through 10 or so binders with SMD parts as well as some other places.
It'll take a while I'm afraid.
I've populated all parts on the boards 🙂
Left to do is clean the boards and put them in an enclosure and hook it all up.
I haven't decided on which enclosure to put them in, I'm going with two transformers each being 12-0-12vac 1500mA. So dual mono all the way (except for the volume control, stepped ladder attentuator, that is).
I have several stepped attentuators, 10K, 50K, 100K. Not sure which is the best option for this design?
Left to do is clean the boards and put them in an enclosure and hook it all up.
I haven't decided on which enclosure to put them in, I'm going with two transformers each being 12-0-12vac 1500mA. So dual mono all the way (except for the volume control, stepped ladder attentuator, that is).
I have several stepped attentuators, 10K, 50K, 100K. Not sure which is the best option for this design?
