5401 and 556 have different pin connections. The emitter and collectors are opposite. Beware if you swap these transistors.
Wrong transistor connections = speaker output will go high or the low rail. The differential amp won't work.
Regards
Wrong transistor connections = speaker output will go high or the low rail. The differential amp won't work.
Regards
thanks i noticed this when I swapped out the BC547 for the 2n2222 trans. I assume your talking about the to92 transistors.
This is a must read thread for P3A lovers. Actually there are a lot of fun threads on this amp. Still reading.
https://www.diyaudio.com/community/threads/p3a-comparison-table-long.164756/
This is a must read thread for P3A lovers. Actually there are a lot of fun threads on this amp. Still reading.
https://www.diyaudio.com/community/threads/p3a-comparison-table-long.164756/
One more schematic to throw into the mix
https://www.diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/page-61
I have some from other sites but not sure how linking to other forums will be taken.
https://www.diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/page-61
I have some from other sites but not sure how linking to other forums will be taken.
https://www.diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/page-61
Can somebody help me get the spice modell shared to run I asked on the thread but no response.
Can somebody help me get the spice modell shared to run I asked on the thread but no response.
Thank you sir.
That worked.
I still got a few errors.
Unknown model type "q2sa1407_syn08" -- ignored
V1: both pins shorted together -- ignoring.
V2: both pins shorted together -- ignoring.
WARNING: Less than two connections to node NC_01. This node is used by R8.
Direct Newton iteration failed to find .op point. (Use ".option noopiter" to skip.)
I am trying to study the impact bootstrap cap and feedback cap values have on the operation of the amp.
What parameters should I be focusing on.
The other thing Im struggling with is understanding how changing transistors used impacts the working of the amp.
i.e. I have various NPN TO92 transistors pulled from high end amps and would like to know how changing these would impact the working of the amp.
That worked.
I still got a few errors.
Unknown model type "q2sa1407_syn08" -- ignored
V1: both pins shorted together -- ignoring.
V2: both pins shorted together -- ignoring.
WARNING: Less than two connections to node NC_01. This node is used by R8.
Direct Newton iteration failed to find .op point. (Use ".option noopiter" to skip.)
I am trying to study the impact bootstrap cap and feedback cap values have on the operation of the amp.
What parameters should I be focusing on.
The other thing Im struggling with is understanding how changing transistors used impacts the working of the amp.
i.e. I have various NPN TO92 transistors pulled from high end amps and would like to know how changing these would impact the working of the amp.
Ive made some progress it may help others.
Ive given up on using the scope other than for basic troubleshooting and big picture THD.
Ive shifted to using ARTA software along with a few other good spectrum analyser.
This gives me a clear shot view of THD + Noise.
Now every mod or change I try gives me a clean picture.
Ive given up on using the scope other than for basic troubleshooting and big picture THD.
Ive shifted to using ARTA software along with a few other good spectrum analyser.
This gives me a clear shot view of THD + Noise.
Now every mod or change I try gives me a clean picture.
Dear friends. my pcb's are ready but I want to ask if I can use 2SD1047/2SB817 pairs for P3A amplifier? My PSU is +/-36.5 volts and speakers are 6 Ohms rated.
That output transistor combo might work. There could be some instability to be dealt with.
If you are able to troubleshoot and fix any issues that arise then go for it.
If you are not so confident then best stick to the transistors that rod recommends.
I tried substituting the driver transistors for a non recommended type. Gross oscillation was the result. When I went back to bd139/140 I had no problems.
If you are able to troubleshoot and fix any issues that arise then go for it.
If you are not so confident then best stick to the transistors that rod recommends.
I tried substituting the driver transistors for a non recommended type. Gross oscillation was the result. When I went back to bd139/140 I had no problems.
Bd139/40 pair is a fine driver transistor candidate, even Rod Elliott using those in his reference system.
Sadface, thanks for your answer, recommended transistors are 16.5 $ each here at local shops, I think a bit expensive. I have bunch of D1047/B817 and C5198/A1941 pairs already, thats why I want to use them.
You better use 8ohm, otherwise try different output transistors. Tip35/36C aren't that much expensive.
Yes those output transistors are not that expensive. I have no great knowledge about amplifiers but if I change the values of R11 and R12 for like 330R?
That not going to help you because 220R is already high. If you increase the value of R11, R12 it may cause instability. Still If you're not satisfied by my advice then wait for other forum member or select an another design where you can use parts you've in your hand.
Best Regards
Best Regards
No need to thank me, we are here to help each other. Just buy original TIP pairs from reputed supplier. Greetings from India.
They always sounded somehow bass-poor, lame, overcast. Almost all TIPs have so far been suitable for audio.
Choosing TO-220s (TIPs) would make the sound even more fluent, smoother and clearer.