Common Ground Layout & Manual Work !

[-_nando-_]

Hey hey hey !

I'm building a BPA200 chipamp, and I want to show you how the things are going, heh, isn't much but I think it's being well done !

No software, no new parts, just the chips, heatsink and the transformers heh! Cheap? CHEAP !


That enclosure was a CCE receiver, veeeery old that had no way to fix, lots of bad things were done inside, so I bought it for 12 Us dollars and I decided to remove everything inside and build the amp. This will be a Hi-Fi guitar amp !


As I said, not much but I'd like to share with all of you !

Pictures are in the ZIP files !

http://files.upl.silentwhisper.net/u...BPA200_1st.zip

http://files.upl.silentwhisper.net/u...BPA200_2nd.zip

Play some attention on the common ground layout, I prefer this way, because the ground impedance become near to zero (nothing have 0 ohms of impedance ! ), and I think this prevent static electricity, oscilations and noise.

YES ! The pcb is being made from that sketch on the paper, nothing else.

The board fits perfectly on the chips, and the procedure was very simple to do that, I've just got a piece of paper and made the decal of the pins on that, then I placed it on the board and pierced it!


I'll be very careful with the power supply, the layout allows to put snubbers on a easy way. The buffer stage will not be in the board of the 3886s, because I want do it separately, then I can do it many times (till I get no noise) without have to replace all the power amp board. I'm a bit worried about the capacitance of the supply, I have four capacitors of 4,700uF @ 63V, may I loose quality on high frequencys? Should I use just two capacitors instead four?

Power supply is in progress yet ehheh




Waiting for feedback !



Thankssssss !!!

[-_nando-_]

I'm thinking of a tube buffer ! Any sugestions?

[-_nando-_]

Design Goal !








After burn some chips because a little of neglects (I was VERY anxious), I decided to calm down and take lots of more care.


First, was something wrong with the supply, and 4 chips were gone hahahahaah

Then, the problem was the isolation of the chip, and more one was gone !


I don't find money on the trees, so I built a supply with fuses and 100Ohms resistor on each rail (without resistor on GND), and built the amp again.

For precaution, I built first the inverted and then I'll build the non inverted. Just because if something go wrong, I don't loose all the chips...


Right NOW I played the thing ! The Inverted part is singing VERY WELL, with 2 (TWOOO) mV of offset in one channel and 1.8mV in the other ! Really NICE to see a thing like this !!

Theres NO noise in the loudspeakers, you can put your ears on the tweeters, and you will NOT listen anything ! There's NO hummm to, absolutely NOTHING ! I think the common ground layout helped to achieve this a lot, and I bypassed the chip (on it's pin, most near is impossible) just with a 100nF capacitor ! The power supply uses a 5.000UF cap on each rail, and nothing else. The output isn't bypassed, and don't need to be !

Because of the very little offset, I don't think that I'll have problems in paralleling it right!?


I'll post here the next step, the non inverted part, soon !

[-_nando-_]

Sooner than I imagined ! hehehe


I built the non inverted part, and... ... another goal !!

2,7mV of off-set voltage in one channel and 1,2mV in the other !!

Again, no noise and no hummmm.


Now, I'm gonna parallel the two inverted and the two non inverted, I'll test the two parts again and then bridge it !