Point-to-Point LM3886

[wintermute]

OK So you mean you left out the CS caps (local decoupling caps) on the first schematic? You have filter caps in your PSU...

I originally built with only 1500uF/rail in the PSU but I increased it by adding an additional 4700uF per rail.

There were comments about longevity of the caps in my build due to proximity to the chip earlier in the thread. I'm happy to say that 9 years later (with daily use) there hasn't been any problem. Adequate heatsinking does the trick

edit: I suddenly got the feeling that Andrewt would normally chime in about now about all of the additional protection components, like the zobel and feedback cap
edit2: knowing my recent luck, it will probably die tomorrow now
Tony.

 

[petrnyc]

No sorry, The schematic is all followed, the CS caps are There and are 2200mf And Each has 0,1 Cap as well.

What I meant is The Power supply has no Filter caps and the + & - v goes in as in the schematic. Direct right off the rectifier bridge.

No problem, I just wanted to know if someone built it just like me and than decided to go and Add 10000mf filter Caps in the PS.
And if there was a difference in The sound and what the difference was.

I am Still planning to add zobel and fix the star grounding.

As it is it does sound fresh, fast (not sluggish) and surprisingly bass Is powerful and instruments sound very good.

Thanks

 

[Mark Whitney]

That is how the gaincard was designed. 1000uF capacitors located at the shortend power pins of the IC. Paralleled capacitors interact with each other that produces oscillations and increased impedance at certain frequencies.

 

[petrnyc]

Hi All,
Couple of days ago, I have finished the Mick Feuerbacher Minimalist lm3886 amp.
See hereMick Feuerbacher Audio Projects)

Followed the very same schematic he used except I had some cheap XY boards that I used (so not point to point, but close....).

Mick was going to use PS with some capacitance.

Mine only has 2200mF decoupling cap per side and no other capacitors in power supply are in use, the + and - rails go straight to the chip and the 2200 mF caps.
Used star grounding.

Its very quiet, quick, instrument sound true, really surprised by the sonics.

 

[brodjack]

I just jumped onto the LM3886 amp 'thing'.
usually,albeit many yrs ago, mainly valves.Bought some prebuilt boards and matching psu board,using a 25-0-25 300va tranny.
replaced the 15pence 1uf coupling caps with some old Hovland 1.5uf Musicaps I had from many yrs ago..
Amazed how such a simple cheap amp can sound so good..it has great dynamics,even 'air' between the instruments almost single ended valve style..very tight bass and extended treble...
Input matches my Agptek flac files player,which has a remote volume control..
cant stop listening to the music lol