Which pins exactly do you mean? Looking at the image with my measurements those pins with +-33V are labeled V+ and V-. I was thinking that this is fine.
Or did you mean the 0.33V values?
Cheers and thanks for the help. It's highly appreciated.
Alex
Today I received the new LM4780TA chip. I sodered it to the board and made sure i don't have any shortages.
Turned it on. Power drain is constant at around 10W. This made me optimistic.
Then I tried to measure some voltages. Ground from the multimeter was connected to the gorund between the two electroltic condensators of the power supply. I realized that the relays are not switching.
On the audio input ground pins JP2 & JP3 (jumpers inserted for noninverting mode) I measured -15V which made me unoptimistic.
I was only able to find out that the voltage drop on D3 (the 6V8 zener diode before the -12V regulator) was 0V where the voltage drop on D1 was around 6.8V. Which means D3 is defect.
Please correct me if I'm wrong. As far as I see this, this should not have much influence except higher load on the -12V regulator. This cannot be the answer to my -15V at the gorund pins of the inputs.
Turned it on. Power drain is constant at around 10W. This made me optimistic.
Then I tried to measure some voltages. Ground from the multimeter was connected to the gorund between the two electroltic condensators of the power supply. I realized that the relays are not switching.
On the audio input ground pins JP2 & JP3 (jumpers inserted for noninverting mode) I measured -15V which made me unoptimistic.
I was only able to find out that the voltage drop on D3 (the 6V8 zener diode before the -12V regulator) was 0V where the voltage drop on D1 was around 6.8V. Which means D3 is defect.
Please correct me if I'm wrong. As far as I see this, this should not have much influence except higher load on the -12V regulator. This cannot be the answer to my -15V at the gorund pins of the inputs.
Hi Peranders,
I just wanted to write that I found the mistake, R27 was ways to high and therefore my ground on the opamp side was totally disrupted. Your expertise just proved that this must be it.
Replaced it with a 2.2 Ohm resistor --> looks very good. now doing some audio testing
Thousand thanks peranders.
only across one of them (the other one seems to be broken -> i have -34v on the input pin of the voltage regulator). thinking of using 18v zeners to relax both voltage regulators.
i realized, that the amp and preamp are very sensitive. i had to put my mobile phone outside the room and shield the raspberry pi dac because of the noise the pa03 picks up.
the sound is amazing. even with my current speakers.
next step are enclosures for the pa03 and my mezmerize b1 buffer to keep the noise outside. my diy speakers will be finished next month.
has anyone tried burson audio v5 opamps with the pa03?
i've updated the album
at the end of the album are some oscilloscope images. with the signal generator and both pi and wifi bridge off, the signal was without noise.
because of the WAF i wrapped up everything. as already said, when using the signal generator as input for the preamp, the signal looks very clean. as soon as i turn on the wifi bridge and the raspberry fi i have noise on my pa03. will keep you posted when i do some measurements again.
@peranders: no noise when i connect the inputs to ground
after i moved the raspberry pi dac a cable length of 1.5m away from the amp and shielded the inputs, i had no noise any mkre when playing music.
i will replace the zener diode asap. after that i think the amp is finished electrically. if anyone is interrested i can keep you informed about how the burson audio opamps perform.
after i moved the raspberry pi dac a cable length of 1.5m away from the amp and shielded the inputs, i had no noise any mkre when playing music.
i will replace the zener diode asap. after that i think the amp is finished electrically. if anyone is interrested i can keep you informed about how the burson audio opamps perform.
Samuel Groner has measured this opamp.
http://www.nanovolt.ch/resources/ic_opamps/pdf/opamp_distortion.pdf
Update: Burson Audio V5S - OPA143PA replacement
I received yesterday my Burson Audio OPAMPs. Wasn't able to use them until today. There was not enough space to insert them into the soldered sockets. I had to add two 8-pin sockets to each soldered socket.
In my subjective opinion the sound improved compared to the OPA134PA's. The stage is wider and the location of each instrument is easier to find (when i close my eyes).
Compared to the OPA134 the Burson OPAs get warm. Seems that they need more power. Thanks to Pavel and Per there's more than enough power available.
I really like the Amp. It's a cool starting project and the results are very sattisfying.
@Per:
I also replaced the Zener diode. I have 8.72V voltage drop compared to the exact 8.6V at the Zener diode which was working properly. Even if the voltage regulator was working properly, I would always know that there is a faulty component in my Amp.
I'm quite happy with the Amp. I was able to identify the source(s) causing the noise.
1. Switching power supply of my Linksys WUMC710 WiFi bridge
2. Noise on the Raspberry PI via the LAN cable connected to the WiFi bridge
Got also a Raspberry PI3 which has WiFi onboard and makes the WiFi bridge obsolete.
I received yesterday my Burson Audio OPAMPs. Wasn't able to use them until today. There was not enough space to insert them into the soldered sockets. I had to add two 8-pin sockets to each soldered socket.
In my subjective opinion the sound improved compared to the OPA134PA's. The stage is wider and the location of each instrument is easier to find (when i close my eyes).
Compared to the OPA134 the Burson OPAs get warm. Seems that they need more power. Thanks to Pavel and Per there's more than enough power available.
I really like the Amp. It's a cool starting project and the results are very sattisfying.
@Per:
I also replaced the Zener diode. I have 8.72V voltage drop compared to the exact 8.6V at the Zener diode which was working properly. Even if the voltage regulator was working properly, I would always know that there is a faulty component in my Amp.
I'm quite happy with the Amp. I was able to identify the source(s) causing the noise.
1. Switching power supply of my Linksys WUMC710 WiFi bridge
2. Noise on the Raspberry PI via the LAN cable connected to the WiFi bridge
Got also a Raspberry PI3 which has WiFi onboard and makes the WiFi bridge obsolete.
I went to a electronics high school.
For me it's a starting project, because it comes with lots of bells an whistles like power up delay. It was a great learning experience.
When I finish the enclosures, the DCB1 PA03 combination will play music while I'm working on my Pass FT5 Turbo mono blocks.