Thanks Klaus 🙂
Interesting....
I'm already using a non- polar (BG NX), good to know 😉
Interesting... what about the mute function of LM3886?
Do you think it's still functional?
Remember, I can/will buy from U.S. suppliers and ship over the pond via snail mail (USPS) at a big savings in most cases. Just shoot me a PM.
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I have addressed that in the original MyRef thread, but it seems interesting that this idea caught on. Do you use 220uF or larger value?
No, I just returned the speaker GND to the central GND (PGND). Power-Up/Down noise is overrated anyway, given that in normal use the speaker has to take transients that are very much higher. Unless the cone really jumps out there is no problem, same with some outburst of HF oscillation which often takes places shortly before the supply is fully down (both points are NO issues with the MyRef, just a slight "click" is produced). Key point is to use not too much of main supply capacitance, anything above 10mF per rail looks overdone to me for this kind of amp (and for a MyRef with its excellent supply rejection anyway).
I'm using 220uF 6.3V Black Gate NX.
But the only reason I've started using it is that it sound even better than BG FK.
Now it seems there are additional reasons 😉
Haven't tried with LM3886 in a composite, will check. With the TDA7294 full standby protection works well this way as the ouputs are fully off then.
Mute pin works. Only a slight click when shorting it to GND in the current setup.
Checked with the simplicistic datasheet circuit 47uF slowing cap plus 10k to V- (operate) or left open (mute), too. Unmute is quick, mute goes through a short distortion fade.
Checked with the simplicistic datasheet circuit 47uF slowing cap plus 10k to V- (operate) or left open (mute), too. Unmute is quick, mute goes through a short distortion fade.
Yes. For use in this amp (supply sensing for on/off and latching DC/supply fault protection) a more complex circuit would be needed... a few trannies, R's and C's.
Dario can you say again how to you recognize/identify the sense of capacitors like Wima FKP2 or Amtrans? Grazie !
Bucharest Audio
Off topic.
It must be exciting to be in Bucharest these days. Based on the involvement in these forums, there is a lot of DIY audio going on. We have Atupi here and elsewhere involved. The Russian polystyrene cap supplier. And Tibi over on the Shigaclone thread re-inventing the CD transport. Sounds like great fun.
Jac
Off topic.
It must be exciting to be in Bucharest these days. Based on the involvement in these forums, there is a lot of DIY audio going on. We have Atupi here and elsewhere involved. The Russian polystyrene cap supplier. And Tibi over on the Shigaclone thread re-inventing the CD transport. Sounds like great fun.
Jac
Standard Class-II SMPS tend to have tons of nasty leakage current, the last thing you want to have in an audio system.
Class-I often are not much cleaner, either.
The only standard types that are suitable to audio without risk are those SMPS rated for medical use (hence very expensive).
Further problem : Voltage drops heavily when overloaded (current limiting) instead of switching off. You must use SMPS with ample current capacity (using worst case assumptions). Additional caps, if too big, cause startup problems.
SMPS for power audio power amps is a very special art.
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Most of the times you should test them both sides since markings are sometimes different from batch to batch.
If you would like to know how to identify by listening which side is 'the right one' I use mainly bass performance.
The right one has the fattest and roundest bass, the wrong one snappy and overly controlled.
Usually the wrong one has bigger sound stage and often sound a bit harsh.
In two words the right side sounds fuller and sweeter
If you have access to an oscilloscope there are several methods to identify the outer foil of the cap (do a Google search).
The outher foil should go the point of less impedance to ground.
At this page you can find further examples on where to put the outer foil.
Caps used in the FE seems pretty consistent (Wima FKP2, Amtrans AMCH, KP1834)
Wima and Amtrans seem to have the outer foil at the end of markings (100nF = --->), KP1834 the opposite (10nF = <---).
BTW I've read on this forum that FKP2s can vary from batch to batch and my Audyn True copper have 2 different orientation (one has the outer foil at the end of markings, the other at the beginning...)
I received a shoebox size package from mouser today jambed full of little bags holding components. I am so, so glad I took the time to transfer the location designation from the BOM to my order! I see a lot of time with an iron in my future😀
Off Topic
Bob,
Perhaps I was exaggerating when I said re-inventing the CD transport. They have got a board designed with good attention to details that will control an available CD drive. Early will have SPDIF out, later your choice of digital format. I would start looking around mid Feb 2012, post #5228. The posts are over 5800 now. Happy reading.
http://www.diyaudio.com/forums/digi...rdable-cd-transport-shigaclone-story-523.html
Bob,
Perhaps I was exaggerating when I said re-inventing the CD transport. They have got a board designed with good attention to details that will control an available CD drive. Early will have SPDIF out, later your choice of digital format. I would start looking around mid Feb 2012, post #5228. The posts are over 5800 now. Happy reading.
http://www.diyaudio.com/forums/digi...rdable-cd-transport-shigaclone-story-523.html
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