my 2x LM3886 in parallel amp finished - Page 4

CJ900RR · 26th March 2009, 02:52 PM

I assumed that he wanted > 100W into 8 Ohm, that's why I recommended the bridged version. We don't even know if he is going to use ±30V supply rails.

But, I don't event know if you are questioning my previous answer.

AndrewT · 26th March 2009, 04:47 PM

I think the parallel 3886 for a severe reactance 8ohm speaker is an excellent idea.

Each amp thinks it is driving a 16ohm load and thus produces less distortion.
Each amp runs cooler and so triggers Spike protection less often.
Each amp contributes to the current demand of the speaker which a single can never match.

The downside is that a parallel setup probably does not work quite as well as a single, but I think this is outweighed by all the advantages.

Ensure that each 3886 has +-10mF on it's power rails to get deep bass that when paired can control any 8ohm speaker.

You could push the PSU voltage right upto maximum i.e. use a 28Vac transformer. To give slightly more headroom for transients.

alexw88 · 27th March 2009, 12:27 PM

Quote:

Originally posted by pachy
What about my request If you don't want to post them in the forum you can email me the files. Thanks.

Sorry for late, did not check this forum lately....

The PADS PCB file is at http://www.shine7.com/pa100_routing5a.zip

Note that this is not a good layout, the drill holes are not big enough and the components are put too close together. I suggest you do some modifications.

Beftus · 4th April 2009, 08:08 AM

Quote:

Originally posted by AndrewT
both low pass filters will work.
the 22k may be slightly noisier.
be prepared to experiment with the RC value to suit your ears and speakers.

I went for a ~1us RC-filter giving a cut off frequency of approx 156KHz. Two 680 ohm + 1.5nF filters cured my dual mono amp from all kinds of annoying pops and clicks. It's now dead silent. Again, thanks for the input!

ambed · 23rd July 2009, 06:04 PM

sorry for old post resuming,but I wanna ask mybe someone can convert this pcb layout to other extension layout(.lay or other) thanks

larryg · 24th July 2009, 05:49 PM

Very nice work!

ambed · 26th July 2009, 12:41 PM

maybe there are other program that can open PADS .pcb files??

26th March 2009, 04:47 PM	#32
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I think the parallel 3886 for a severe reactance 8ohm speaker is an excellent idea. Each amp thinks it is driving a 16ohm load and thus produces less distortion. Each amp runs cooler and so triggers Spike protection less often. Each amp contributes to the current demand of the speaker which a single can never match. The downside is that a parallel setup probably does not work quite as well as a single, but I think this is outweighed by all the advantages. Ensure that each 3886 has +-10mF on it's power rails to get deep bass that when paired can control any 8ohm speaker. You could push the PSU voltage right upto maximum i.e. use a 28Vac transformer. To give slightly more headroom for transients. __________________ regards Andrew T.

24th July 2009, 05:49 PM	#36
larryg diyAudio Member Join Date: Feb 2004 Location: cary,n.c.	Very nice work! __________________ larryg

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26th March 2009, 02:52 PM	#31
CJ900RR diyAudio Member Join Date: Jan 2006	I assumed that he wanted > 100W into 8 Ohm, that's why I recommended the bridged version. We don't even know if he is going to use ±30V supply rails. But, I don't event know if you are questioning my previous answer.

23rd July 2009, 06:04 PM	#35
ambed diyAudio Member Join Date: Jun 2009	sorry for old post resuming,but I wanna ask mybe someone can convert this pcb layout to other extension layout(.lay or other) thanks

26th July 2009, 12:41 PM	#37
ambed diyAudio Member Join Date: Jun 2009	maybe there are other program that can open PADS .pcb files??

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