Hi everybody, the matching is not really that critical or difficult.
On the input stages, the absolute BEST would be to have 8 PNPs and 8 NPNs that have matched gain, collector-base leakage current and no noise issues.
Unfortunately that will require expert equipment, so we can make do with just matching 8N and 8P with current gain, that is good enough in 99.9999% of the cases. To match the current gain between the left and right channel input stages will help to remove gain differences between the channels, helping imaging. If that cannot be done, at least the NPNs and PNPs of the input stage should match between each other (within N and within P separately, that is).
This input stage is the key piece of the amplifier, so spending time to make the match as good as possible is definitely worth it. While you are at it, you may want to match the 33Ohm resistors as well, their influence is less (and 1% resistors are already pretty good), so that may be borderline to overdoing it.
How good is good enough? If you can get the matching down to +/-10% that is good. More precise is better of course but obviously tends to be a little difficult. My recommendation would be to try and achieve closest possible matching for the input stages, and then match every other subcircuit within itself.
For the other subcircuits of the amplifier, take a look at the schematic in the assembly guide, it has circles around sections of the circuit in which the transistors should match to each other. They do not necessarily have to match to the other devices. This is because the transistors in these subcircuits work closely with each other, and outside of those the absolute parameters don't matter much for the function of that subcircuit, thanks to the great design that MiiB did.
On the absolute numbers, the circuit will work with pretty much all the values in the -40 grade, so thats not an issue. The team has a feeling that if the current gain gets very high (above 550 or so), the amplifier may have a tendency to oscillate, but we did not perform all the tests to make sure that that REALLY is the reason. It is clear though that with lower values it should not oscillate. My recommendation would be to use values around 400 for both N and P for the input stage, whereas the other parts of the circuit can use higher gains (but please make sure you have those decoupling caps in place on the bottom side of the PCB).
Hope that makes it clearer!
Told you so in post 568
Sems that placing spelling mistakes on my posts to keep you lot attentive does not work anymore
YEA HE IS blipping blopping sure
10 % is cooooooooooooool but 5 is beter but not so cooooooooooooooool if it get you worry
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After a new order of BC 337-40 of Conrad, I got two sets of about 50 trannies (337 and 327) within hfe of 450 to 470.
Lucky me!!
May I match the groups even closer then?
-Or is that to much?
thats great! 450-470 is very good, no need to get closer.....
I am starting a new tread on the Swap forums
This should free up the builder tread for trouble shooting and builds tips
In the meantime
I have started to measure the BCXXX-40 I got with goodies bags (Paradise GB)
I tried the Atlas unit again and first test on a sample measure first test Hfe 477 a second test few seconds later measure Hfe 481 is not a big difference considering the 10% tolerance recommended
Measuring with the circuit published by Hesener give me an Hfe of 493 and repeating this give me exactly the same results
I like to test using Hesener circuit as I can see what is happening especially with the problems arising from touching the transistors
Considering that to build this circuit is really inexpensive I am going to stick with it.
BCxxx 40 004 - YouTube
This should free up the builder tread for trouble shooting and builds tips
In the meantime
I have started to measure the BCXXX-40 I got with goodies bags (Paradise GB)
I tried the Atlas unit again and first test on a sample measure first test Hfe 477 a second test few seconds later measure Hfe 481 is not a big difference considering the 10% tolerance recommended
Measuring with the circuit published by Hesener give me an Hfe of 493 and repeating this give me exactly the same results
I like to test using Hesener circuit as I can see what is happening especially with the problems arising from touching the transistors
Considering that to build this circuit is really inexpensive I am going to stick with it.
BCxxx 40 004 - YouTube
100 % with this
1000 each how long? how many time you press scroll buton on Atlas how many batteries one uses?
Swap tread started post on how not to waste time linked (post 2)
http://www.diyaudio.com/forums/swap-meet/226166-paradise-bcxxx-40-a.html#post3293858
PS I am not after fame or profits and my R2 is fine and got plenty to build R3 so if you have constructive coments great if not "have a nice day" or the more apropiate Queen English translation for it
I am going to populate the R3 boards with 5XX for current sources (done the same for R2 after all) and with the highets matched Hfe I got for the Imputs.
No not today but eventualy
If those oscillate I may need hesener help (Seepost 567) so I may have to volunteer as volunteer N1 but don't think so...
No not today but eventualy
If those oscillate I may need hesener help (Seepost 567) so I may have to volunteer as volunteer N1 but don't think so...