BPA300 mono block finished and measured

Finally I tried the LL1545a in my BPA300 :

http://www.shine7.com/audio/bpa300v2.htm

I am now building an active balanced pre-amp to pair with it :

http://www.shine7.com/audio/bpre.htm

Currently I am now using a full balanced connection from the CD player to Preamp to BPA300. The current setting sounds more musical to me. Also by removing the input caps the amp sounds more transparent than before.
 
They do have some good DIY components, but you need to know Chinese to buy from them.

Transformer wiring is very simple :

ll1545a.gif
 
Transformer can + core are connected to signal ground. (as in http://www.lundahl.se/pdfs/datash/1545a.pdf)

Pin 1 is now left open, I have my XLR cable shield connected to my pre-amp's ground.

> Are there any situations where the normal connection rules for those two grounds should not be followed?

Yes, when you are lazy or when your are trying things out. :D
BTW, I found there are so many connection suggestions for XLR cables, what is normal?

1. http://www.vandenhul.com/artpap/wiring1.htm
2. http://www.jensen-transformers.com/as/as089.pdf
3. http://www.epanorama.net/documents/groundloop/groundlift.html
4. http://www.rane.com/note110.html

Rane suggest connect the shield (pin 1) directly to earth. But I prefer Jensen's suggestion of connecting pin 1 to ground via a resistor + capacitor.
 
Hi Alexw88,

This is not 100% Finished, Chassis not yet anodized and i will modify PSU using Carlosfm design and change the trafo with 300VA 2x25

I will use this PA150 for my front end Home theater.
I build this with standart part and only cost me around $200... so far i'm very happy with it.

After this i will build 5 channel PA150... soft start+speaker protector.

Alex, Why you don't want to make another PA150 beautiful pcbs , I sure some people in this forum have interest to build BPA300,
If you don't like to manage logistic, i will help you to do that or even they want soldered smd part... i can do that too...

Best Regards
Jopie
 

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You can't remove them. See the app note AN-1192 for details, here is the quote :

1% tolerance high wattage ballast resistors are required
when paralleling outputs to keep differently biased outputs
from fighting each other. The wattage rating is dependent
upon the amount of current expected to flow
from each output and the resistance of the ballast resistor;
P = I2R. A good resistance value is 0.1Ω. Amplifier
efficiency is lost if the resistor value is too large like 1Ω
since 10A times 1Ω is 10V of output voltage drop.