I have read a few papers from Bill Whitlock, and have learned a lot from them. But I do not recall any actually describing the change in perceived sound quality. I will check again.True enough - to get a handle on those I suggest looking out for a paper (which I've not read as its behind the AES paywall) of Deane Jensen - google for 'Spectral Contamination'. Bill Whitlock carries on the good work over at Jensen Transformers nowadays so he might be a good person to ask about audibility.
It very much depends on the whole system grounding - whether balanced or unbalanced cabling is used for example. The mechanisms for coupling are clear though - much depends on the resistance of amp to RF ingress. This I believe is the reason many audiophiles turn up their noses at IC opamps
I can tell you now that I am willing to stand a LM3886 chip amp up to any commercial amp for loads between 4ohm and 9ohm. Circuit is the standard NS data book, just special attention to power supply matching/decoupling.
Do you have insulation between the LM3886 abd heat sink? I sometimes forget them after a swap around.
My take on the best possible decoupling scheme for a standalone LM3886 :
Shown is the basic principle only (referring GND to a non-rippling neg supply to make use of the much better PSRR of the pos rail of the LM).
Will post full schematic and working amp with measurements some day (as I promised when I first posted this).
But we are polluting the FE thread here...
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No, just white heat sink paste but it is a LM3886TF.
I think the zeners at D105, D205 are in correct direction.
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Andrew, see this thread's section for some details. I'm still refining the circuit to make it bullet-proof for DIY. I might go back to the standard approach and make only the MF/HF decoupling this way, see also ThorstenL's comments.
It's perfectly fine, no need for insulation with TF.
Yes, they are but I thnk Klaus was referring to D3 (27V one between BAV99s).
Can you post a clear picture of the bottom of the board?
Firm hand, a lot of light and macro mode.
It's correcty oriented.
But I see a lot of possible cold joints and solder bridges.
You probably use a too low temperature with you soldering iron, it should be at least 320°C.
Looking back on it, I'm sure on part of the build it was too cold. I have one of those Stahl variable temp w/ chisel tip from Parts Express. This build was the first time I used it. Now I see that 350C setting gives that 1 second melt we look for.
Thanks for the help guys. No more troubleshooting for me till Monday, work calls and I have new people on my crew.
Thanks for the help guys. No more troubleshooting for me till Monday, work calls and I have new people on my crew.
I have introduced concept in the original MyRef thread. The current configuration is working better than I expected. But the design is proprietary. Both the configuration and values effect sound quality.My take on the best possible decoupling scheme for a standalone LM3886 :
Shown is the basic principle only (referring GND to a non-rippling neg supply to make use of the much better PSRR of the pos rail of the LM).
Will post full schematic and working amp with measurements some day (as I promised when I first posted this).
But we are polluting the FE thread here...
http://www.diyaudio.com/forums/chip-amps/54571-my-audiophile-lm3886-approach-392.html#post3029324
http://www.diyaudio.com/forums/chip-amps/54571-my-audiophile-lm3886-approach-392.html#post3029094
C7 is actually 0.15uF when I looked the other day
The switching modules are off-the-shelf which I mentioned here
http://www.diyaudio.com/forums/chip-amps/196237-my_ref-revo-5.html#post2720051
This is enough for people to DIY. Nobody to date seemed interested though.
The line filter and additional matching with the circuit is proprietary.
http://www.diyaudio.com/forums/chip-amps/54571-my-audiophile-lm3886-approach-392.html#post3029094
C7 is actually 0.15uF when I looked the other day
The switching modules are off-the-shelf which I mentioned here
http://www.diyaudio.com/forums/chip-amps/196237-my_ref-revo-5.html#post2720051
This is enough for people to DIY. Nobody to date seemed interested though.
The line filter and additional matching with the circuit is proprietary.
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They seem good measures, a bit on the low side but probably it's the transformer regulation.
Didn't used the Chip Quik desoldering alloy?
With it it's easy to desolder SMD chips without doing any damage...
Can you post a picture?
It should be possible to made a repair with a bit of copper wire or using a conductive silver pen.
Or, maybe, you're lucky and the lifted pad is one of the not connected ones.
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