BPA300 mono block finished and measured - diyAudio
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Old 29th September 2005, 08:40 AM   #1
alexw88 is offline alexw88  Hong Kong
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Default BPA300 mono block finished and measured

Just finished one BPA300 mono block and used RMAA to do some measurement.

Click the image to open in full size.

RMAA result :

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More photos and details can be found at my site :

http://www.shine7.com/audio/bpa300.htm
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Old 29th September 2005, 09:05 AM   #2
Electrons are yellow and more is better!
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Very nice indeed and you have swedish RIFA caps also

I see also that you have used SMT parts, I like it!

I haven't check your pcb layout in details but it look near 100% perfect. The most critical part is the grounding since you have many amperes.

Is it possible to show as the performance of sound card alone?

Can you also show us the graphs from RMAA? The LM3886 is producing very low numbers I must say.
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Old 29th September 2005, 10:51 AM   #3
Mad_K is offline Mad_K  Norway
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Looks very nice!

Do you have holes in the top/bottom of your chassis?

Looking forward to hearing about your listening impressions when you get your other channel up and running..
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Old 29th September 2005, 11:14 AM   #4
alexw88 is offline alexw88  Hong Kong
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P-A, thanks for your comment!

PCB layout :

Click the image to open in full size.

The sound card itself has THD of 0.0015%, so the THD measurement is very close to the limit of my sound card. I think the BPA300 can actually have a better THD at high wattage.

Click the image to open in full size.


Mad K, my chassis has many holes on the side and top :

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Old 29th September 2005, 11:17 AM   #5
alexw88 is offline alexw88  Hong Kong
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P-A, the RIFA caps is capable of delivery very high current, I accidentially shorted one fully charged 47000uF with a screw driver, a very big spark occured and the steel screw driver had a big dent on the surface!

I love them!
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Old 29th September 2005, 11:31 AM   #6
Electrons are yellow and more is better!
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Have you shaked the RIFA'a? Lot's of fluid inside them.
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Old 29th September 2005, 11:38 AM   #7
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Wow! impressive build & pcb's
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Old 29th September 2005, 12:13 PM   #8
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nice work

i think you have a bit of a.c. leakage which needs attending. if you look at the spectrum analysis -- you have 2 bumps -- one at at 50Hz and another at 100Hz -- you might want to figure a way of getting the hot a.c. wiring away from the gain stages -- i found that when I did this the low level distortion went down several 0.001%s -- twist the a.c. leads a bit more tightly and tack them to the bottom of the chasis with tie-wraps.

It might be too late now -- but I would move the trafo to the center of the box.
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Old 29th September 2005, 04:41 PM   #9
alexw88 is offline alexw88  Hong Kong
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Agreed that the AC line can be twisted tighter and should be placed away from the PCB, I think I will try to re-wire it later, may be to go in between the 2 PCBs?

Moving the transformer is a bit difficult...
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Old 29th September 2005, 05:00 PM   #10
alexw88 is offline alexw88  Hong Kong
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Quote:
Originally posted by peranders

Is it possible to show as the performance of sound card alone?

This is the soundcard loopback test :

Click the image to open in full size.

I can see the soundcard has distortion at 2k and 3k, about -100dB.
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