Did you try the metal can ones ? ....I believe these are even better than the plastic 4562.
Output filter/DAC/HF-amp/decoder/SERVO/Drivers/uController: which of these mods will get rid of a fair bit of noise? Yeah sorry I'm asking again so soon, I'm about to order the necessary parts.
Anyway, the capacitors that need to be removed in the DAC section: are these the blocking caps?
Anyway, the capacitors that need to be removed in the DAC section: are these the blocking caps?
Those metal can opamps are very good!
Cap wise, I'd use something like 220uF ZA's for ultra detail or silmicII if you want a sligthly smoother rounder sound. I'd poss go to 470uF too??
BTW! what bike do you have?
the caps we are talking about are the DC blocking caps after the HDAMs. They only need to be shorted (bypassed) if you retain the HDAM section. They are the 4 slmics closest to the output RCA's at the back of the machine.
Thanks. I have a CD53 which has no HDAM section to start with. I already removed the blocking caps though. I hope that's not a problem? Sounds like a slight improvement to me, though it wouldn't be the first time I'm imagining things
Stabby, what's all this noise you're talking about? If it's the random noise between tracks if you've removed your muting transistors then I can assume you're sitting right next to those monitors and they're turned up loud. I believe there is no easy cure unless you want to reinstate muting.
If you're talking about the huge background hiss, hum and random noises on many CDs then that's all part of the music and your system is revealing it well.
If you're talking about the huge background hiss, hum and random noises on many CDs then that's all part of the music and your system is revealing it well.
It's not helping that noise has so many meanings in English
I'm talking about the constant hiss, which is very audible in between tracks and during quiet parts.When disabling the muting circuit I never added two X7R caps though. That might be the cause? I have no idea where exactly to connect these caps. The mod list says "Decouple each muting line to GND with two 100n/X7R at junctions U222/223 and output side", but that's a bit vague to me.
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It's not helping that noise has so many meaning in English
When disabling the muting circuit I never added two X7R caps though. That might be the cause? I have no idea where exactly to connect these caps. The mod list says "Decouple each muting line to GND with two 100n/X7R at junctions U222/223 and output side", but that's a bit vague to me.
eh?????
Just link the output of the opamp direct to the RCA's. You can remove the original RCA assembly from the PCB and mount it upside down on the rear panel then tag the L & R directly from the opamp and connect a gnd.
You definatley dont need and 100n to gnd in the signal lines which I think is how you are reading this???
Is that a different way of disabling the muting circuit? I have followed Ray's instructions:
"Disable muting circuit: remove QN24/25/91/92 and RN27/28 (cuts analog -12V to muting circuit). Remove U207, U211 and U262 (and cut trace) to disable traces running to headphone section. Decouple each muting line to GND with two 100n/X7R at junctions U222/223 and output side to remove noise coupled-in to analog section from digital-out trace that runs in parallel with muting lines for several inches!!"
Your method seems a lot more simple. I'll just get a better RCA output and mount it on the rear panel. As for the ground, is it alright if I use the same ground connection as the original pcb-soldered RCA?
With what I said you are just taking the audio path direct from the opamp to the output. It's a very simple way to do it but it doesn't take into account the passive components (resistors) that are part of the original output. I never had a problem doing this myself. With rays approach, you are only bypassing the active part of the muting circuit preserving the resistors. Also ray correctly tells you how to isolated the voltage to the muting circuit. As it's no longer being used, you should disconnect it's own supply. If it's not on the rail, it's not polluting it with noise'
Thanks UV101, I greatly appreciate your advice. I just keep learning
There's just one thing that's never been clear to me. I have no idea how to place decoupling capacitors. When you replace a capacitor and you're asked to add a 100n X7R, where does each side of the 100n go? Does it run parallel with the capacitor?
There's just one thing that's never been clear to me. I have no idea how to place decoupling capacitors. When you replace a capacitor and you're asked to add a 100n X7R, where does each side of the 100n go? Does it run parallel with the capacitor?
The x7r's go across the legs of the cap on the underside of the board in parallel with the elco. They are used to help keep noise off the rails.
If you are changing the caps too, I would replace the main smoothers with very high value. Something like 10,000uf panasonic TSUPs (or better if you can afford). Brent found that the servo rails dipped quite a bit during startup. This effects the main 5v rail which is not good. They are physically too large but can be fitted with some imagination !!! ;-)
If you are changing the caps too, I would replace the main smoothers with very high value. Something like 10,000uf panasonic TSUPs (or better if you can afford). Brent found that the servo rails dipped quite a bit during startup. This effects the main 5v rail which is not good. They are physically too large but can be fitted with some imagination !!! ;-)
