RCruz said:
Gain of the discrete stage is reduced slightly to compensate for higher filter output. The gain of the entire circuit remains about the same; the 820 ohm goes hand-in-hand with the different values in the filter (values between brackets, see discrete PDF).
Ray
Before the output dc blocking cap, the reading should be around 6-7volts.
Just to update everyone, I have diy'd some "superregs" and added them to my player. I now have seven "super-regs" of varying kinds in there now. Also added 30va tx to the discrete supply and three smaller tx's for the decoder and servo. The sound is now pretty much awesome, probably about as good as Simon's player (maybe a little better).
Oh, and I must've learned something lately, as I did all that without breaking it, and it's fairly neat too!
Lee.
Just to update everyone, I have diy'd some "superregs" and added them to my player. I now have seven "super-regs" of varying kinds in there now. Also added 30va tx to the discrete supply and three smaller tx's for the decoder and servo. The sound is now pretty much awesome, probably about as good as Simon's player (maybe a little better).
Oh, and I must've learned something lately, as I did all that without breaking it, and it's fairly neat too!
Lee.
Hi Brentrowemeister said:
I still have two psu pcb to use and would like to build a psu for the decoder and HF amp.
While waiting for the discrete parts, I have been reading your pdf http://www.audioupgrades.co.uk/rmcdmodlist.pdf
Just by reading, I can not determine if you use the same 3.2VA 9V tx for the decoder and the HF.
If you are using the same TX, what winding should I use for the HF amp ?
How many diode bridges did you use in your setup ?
Regards
Ricardo
6h5c said:That's better. Looks like you killed the cap--->
--->
You only need a few uF for a -3dB corner freq. that's <<10Hz (with a 47k load), but if you want to keep the group-delay low at the low-end, use 10uF minimum. You should roughly double these values for a 22k load.
Ray
Ray
Well, I ended up ordering a pair of the BG 100uf/16v N caps. I also decided to bypass these with a very small teflon cap. I've just gotten things going again, and the sound is even better than before.
I've been keeping up with the thread, Ricardo's progress, and your explanation of the circuit.
The D.O.S. is fabulous!
Steve
6h5c said:Sweet!
Those caps are quite expensive, but they are worth it! The alternative would be a very large and even more expensive MKP, or tin-foil if you want to reach the same sound quality.
Ray
I used .01uf Sonic Platinums. They are only slightly more than the 100uf BG N cap. Seems to be a nice combo.
RCruz said:
I think he's referring to the discrete output stage.
I'm also using a blend of caps to good effect, but as a general rule it seems unlikely to work.
I use Black Gate AC with Siemens MKV, a physically massive and silly combination.
I think Lee has tried Mundorf MKP bypassed with Supremes and been happy.
Just Supremes would surely be excellent, but veeeery expensive.... and then you have Supreme silver in oil, silver-gold and even silver-gold in oil, if you want to pay hundreds of Euros
Also Tony Gee, famous speaker builder, recommends Clarity Cap SA (which I also rate) bypassed with Mundorf Supreme.
I agree with Ray that BG N and similar types seem not too far off decent film caps.
Simon