FINALLY; I have finished my stereo LM3886 board. - Page 3

Dxvideo · 18th January 2007, 07:46 AM

Do you think still that use a series resistor to 100n? I could hear no noise in my two days performance test. As Nico said i use SMPSs at 30Khz switching freq.

Panelhead · 18th January 2007, 01:31 PM

Very nice layout. Try it for a while and get comfortable with how it sounds. Then lift the leg if the 100n caps that connects to the +/- rails, add the resistors, and give it a listen. Swap back and forth a couple times to be sure that the differences if any are real.
The graphs and waveforms I have seen show the effects to be up in the Mhz range. So the noise is not audible. But the effect on handling music is.
I was a non-believer. Used to just slap small films across big electrolytics. Then quite bypassing because it seemed that the circuits sounded better without. Now I always add the small film caps and low value reistors across the final caps in a filter bank.
One area where you can really here the noise generated by bypass caps is in the first stage of a C-R-C filter. Bypassing the second stage is usually quiet. Bypassing the first stage usually increases the noise. Bypassing on both is usually noiser than just doing the second.
Antway, good job. Making your own PCB's is half the battle.

George

Dxvideo · 18th January 2007, 01:52 PM

OK I'll try it for this PCB in next month. First i must taste my amplifier for a while. I guess its about some modulation! If any kind of RF noise on power line then the amp makes a bit AM on signal, theorcally its not an aboslute mudulation but it seems!
But if that situation exists, then it should be used on every RF circuits. I cannot hear Mhz levels but a RF receiver or transmitter can! In real life is it valid for them?

EdT · 18th January 2007, 06:17 PM

Do not use plumbing flux, you are asking for problems down the road on electronic components. If regular rosin flux is not effective, then your problem is solderbility of your copper traces.

Dxvideo · 19th January 2007, 11:25 AM

I havent tried my amp at full output, and i cannot say i have a problem with my power traces. But i applied the solder support on power traces and as i can see there is no problem with PCB traces except the soldering difficulties on big areas. However i already solved that, may be it doesnt look pretty and have some different tickness on some places but it works for now.

lithoc · 24th May 2011, 05:33 PM

Quote:

Originally Posted by Dxvideo

added some (+7dB) gain on 20Hz-50Hz band. Its for eqalising to my speakers and calculated.

May I know how do you calculate the formula?

Can I add more bass gain, may be 12db++, will it cause sound quality issues?

What about the bandwidth? can it cover more or shift to 50 - 100hz?

Thanks for answering.

18th January 2007, 01:31 PM	#22
Panelhead diyAudio Member Join Date: Dec 2002 Location: Houston	Give it Time Very nice layout. Try it for a while and get comfortable with how it sounds. Then lift the leg if the 100n caps that connects to the +/- rails, add the resistors, and give it a listen. Swap back and forth a couple times to be sure that the differences if any are real. The graphs and waveforms I have seen show the effects to be up in the Mhz range. So the noise is not audible. But the effect on handling music is. I was a non-believer. Used to just slap small films across big electrolytics. Then quite bypassing because it seemed that the circuits sounded better without. Now I always add the small film caps and low value reistors across the final caps in a filter bank. One area where you can really here the noise generated by bypass caps is in the first stage of a C-R-C filter. Bypassing the second stage is usually quiet. Bypassing the first stage usually increases the noise. Bypassing on both is usually noiser than just doing the second. Antway, good job. Making your own PCB's is half the battle. George __________________ Cheapest is bestest

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18th January 2007, 07:46 AM	#21
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	Do you think still that use a series resistor to 100n? I could hear no noise in my two days performance test. As Nico said i use SMPSs at 30Khz switching freq.

18th January 2007, 01:52 PM	#23
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	OK I'll try it for this PCB in next month. First i must taste my amplifier for a while. I guess its about some modulation! If any kind of RF noise on power line then the amp makes a bit AM on signal, theorcally its not an aboslute mudulation but it seems! But if that situation exists, then it should be used on every RF circuits. I cannot hear Mhz levels but a RF receiver or transmitter can! In real life is it valid for them?

18th January 2007, 06:17 PM	#24
EdT diyAudio Member Join Date: Dec 2006	Do not use plumbing flux, you are asking for problems down the road on electronic components. If regular rosin flux is not effective, then your problem is solderbility of your copper traces.

19th January 2007, 11:25 AM	#25
Dxvideo diyAudio Member Join Date: Nov 2003 Location: Turkey	I havent tried my amp at full output, and i cannot say i have a problem with my power traces. But i applied the solder support on power traces and as i can see there is no problem with PCB traces except the soldering difficulties on big areas. However i already solved that, may be it doesnt look pretty and have some different tickness on some places but it works for now.

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