Just finished one BPA300 mono block and used RMAA to do some measurement.
RMAA result :
More photos and details can be found at my site :
http://www.shine7.com/audio/bpa300.htm
RMAA result :
More photos and details can be found at my site :
http://www.shine7.com/audio/bpa300.htm
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.
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.
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..
P-A, thanks for your comment!
PCB layout :
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.
Mad K, my chassis has many holes on the side and top :
PCB layout :
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.
Mad K, my chassis has many holes on the side and top :
An externally hosted image should be here but it was not working when we last tested it.
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! 😉
I love them! 😉
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.
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.
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...
Moving the transformer is a bit difficult...
peranders said:
This is the soundcard loopback test :
I can see the soundcard has distortion at 2k and 3k, about -100dB.
That’s a very professional looking amp. How does it sound? How do you set up the amp for measurement with RMAA? Is the schematic of the amp posted somewhere?
LBHajdu, you can check my web page for the measurement setup and schematic, I only finished one channel so I have not done a proper listening test yet... 
Hope to finish the other channel soon. 😉
Hope to finish the other channel soon. 😉
consider mounting the driver board on the left SIDE of the cabinet, away from the large filter cans. You can rig an L-Bracket to do this.
You have what appears to be a common mode choke on the chassis floor (or is this a choke in the capacitor ground connection to limit the turn-on current surge?). If it's a common mode choke, it could be mounted on the rear of the chasis where the mains come in.
No harm in using microphone cable to route the signals (if you don't have microphone cable, you can use CAT-5 cable with one of the conductors grounded.) I would also use CAT-5 cable for the power of the driver board -- it's pretty flexible and can be tacked to the bottom of the chasis.
When you perform tests with a distortion analyzer put the chasis cover on 😉 Dress your leads so that power is at right angles to signal.
You have what appears to be a common mode choke on the chassis floor (or is this a choke in the capacitor ground connection to limit the turn-on current surge?). If it's a common mode choke, it could be mounted on the rear of the chasis where the mains come in.
No harm in using microphone cable to route the signals (if you don't have microphone cable, you can use CAT-5 cable with one of the conductors grounded.) I would also use CAT-5 cable for the power of the driver board -- it's pretty flexible and can be tacked to the bottom of the chasis.
When you perform tests with a distortion analyzer put the chasis cover on 😉 Dress your leads so that power is at right angles to signal.
jackinnj said:
I connected the PCB ground to the chassis ground / AC main ground thru a choke and a 10ohm resistor in series, the 10ohm can minimize the current flow between the power amp and other equipment, and thus reduce hum. The choke is intended for filtering out the HF noise from the AC ground. I have been searching for a perfect gounding scheme but it seems everyone's grounding method is different.
I am sure the 10ohm here helped a lot to reduce the 50hz hum, but not too sure about the effect of the choke.
jackinnj said:
I am currently using shielded twisted pair for signal, which I think is similar to a microphone cable, right?
A little bit OT
Where in Taiwan did you get you PCB's for your PA100? and do they do Oz. 2? Your PA100 PCB's look just the PCB's I recieved from Peter Daniel and I liked them.
/ Tobias
Where in Taiwan did you get you PCB's for your PA100? and do they do Oz. 2? Your PA100 PCB's look just the PCB's I recieved from Peter Daniel and I liked them.
/ Tobias
tobias_svensk, I got my PA100 PCB from www.manypcb.com and they only have 0.25 (or 0.5??) oz.
However the PA150 PCB is from www.kgs.com.hk they have 2 oz copper and the quality is better.
Both PCB makers are in Hong Kong, I don't know if they will ship overseas or not.
However the PA150 PCB is from www.kgs.com.hk they have 2 oz copper and the quality is better.
Both PCB makers are in Hong Kong, I don't know if they will ship overseas or not.
Finally I finished the other mono block and listened to them for some time.
The sound characteristic of this BPA300 is similar to my other LM3886 and LM3875 gainclone. These mono blocks has deeper sound stage, better stereo imaging, much tighter and better controlled bass.
The sound characteristic of this BPA300 is similar to my other LM3886 and LM3875 gainclone. These mono blocks has deeper sound stage, better stereo imaging, much tighter and better controlled bass.