Now it is a tested pcb!A40 it's😎thanks Mr.Mile ........
Please share this in pdf for home etching🙂
MM22 - RIAA Preamp
Hello Mr APEX!
For your RIAA preamp (MM22 model), my local store does not have 2N5551 and 2N5401. Is the BC640 and BC639 are good replacement?
Thank you!
Hello Mr APEX!
For your RIAA preamp (MM22 model), my local store does not have 2N5551 and 2N5401. Is the BC640 and BC639 are good replacement?
Thank you!
Hello Mr APEX!
For your RIAA preamp (MM22 model), my local store does not have 2N5551 and 2N5401. Is the BC640 and BC639 are good replacement?
Thank you!
Use BC550/560
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A40 pcb files attached 😉Now it is a tested pcb!
Please share this in pdf for home etching🙂
Regards,Alex
Attachments
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thank you thank you very much Alex I was waiting for that 🙂
hey Alex you don't mind if I share this to my friend in facebook ?
I rather ask just in case 😀
Regards
Juan
hey Alex you don't mind if I share this to my friend in facebook ?
I rather ask just in case 😀
Regards
Juan
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Apex A40
All in one.
Thanks Alex!
Thanks Mr.Mile!
All in one.
Thanks Alex!
Thanks Mr.Mile!
Attachments
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Hi Apex
Good job. Your commitment to audio speaks for itself. And Alex as usual is not far behind with a pcb manifestation of most designs on this forum, he may probably write a book soon. Great job to both of you
.
Its been quite a while since I checked out this thread and today there is the A40. Its a design thats an embodiment of various design philosophies and such it is only fair that Alex lays it down for us on how this amplifier compares to SYMEF, having built both.
kind regards
Harrison.
Good job. Your commitment to audio speaks for itself. And Alex as usual is not far behind with a pcb manifestation of most designs on this forum, he may probably write a book soon. Great job to both of you

Its been quite a while since I checked out this thread and today there is the A40. Its a design thats an embodiment of various design philosophies and such it is only fair that Alex lays it down for us on how this amplifier compares to SYMEF, having built both.
kind regards
Harrison.
one friend has done A40(38) pcb´s for me - and now i must do it! 🙂
(Olaf,thanks again for 99% of pcb-work!)
(Olaf,thanks again for 99% of pcb-work!)
Attachments
i will ask my friend what chemical did he used and than i will write here,i don´t know the answer now...
May I ask what you use to tin the copper?

Soft solder paste No. 30 - 0987130
or similar (sorry if this is a comercial but i don´t know how else to describe this product)
it is used for soft soldering of copper tubes. a friend showed me today,it is really easy : use brush to apply paste in about 1mm layer over whole copper side of pcb,than use heat gun // pistol grip hot air gun and heat the paste to about 300°C - if it starts to bubble that is a sign that temperature is too hot. you will see how the surface of paste is getting smoother,apply heat to about one minute (depending on how big is pcb) and than rinse in watter. it takes a try or two to get it right but you have seen the result - it looks great and it is really really easy to do!
i will do a YouTube video as soon as possible to show how it is done - one picture as thousand words,one video as thousand pictures... 🙂
Thanks guys, I will have to give both a try. All part of the DIY experience.
Blessings, Terry
Blessings, Terry
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