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It is currently 16 Sep 2019, 10:20

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PostPosted: 23 Feb 2019, 16:26 
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Joined: 23 Feb 2017, 02:02
Posts: 544
https://eva.fing.edu.uy/pluginfile.php/ ... fineon.pdf
Following the guide online I did measure transtior capacitances along time ago.
With a pF range accurate multi meter one can measure the capacitance at 0v reverse voltage.

It is a good and accurate indication of capacitances and speed of transitor.
Also explains why the swap I had from tip41c dosen't make much diffrence compared to ksd882. The ksd882 was less than 15% faster.

The results clearly show that manufacutres make fake capacitance ratings to lure customers to buy more.
In some cases like bc547 showing like less than 10pF while measured is 30+pF.

I also did make a socket so transitors can be quickly swapped to compare the sound quality, up to to-220 devices could be inserted.
Does still show ksd ksb ksc ksa 2sc 2sa 2sd 2sb to have hard transitor like sound compared to the other models.
Do I think is better to chose 2sc model transitors because is faster? No because I think linearity and warmth is more improtant that outright slew rate and hearing don't go past 20khz.

The japanese on semi bc550 560c does sound very similar to their ksa992 which is very sad, deffnitly not built to the standard bc550 560 specs but to their japanese spec. Poor sound quality.
I do have some chinese bc547 and geniune nos bc547 and they both sounded on a diffrent leage compared to the japanse bc550.
Korean bc546 does sound slightly better than japanse ones but still far off from the 100% genine nos bc547.

I do have a very sensitve to capcitance test amp and does show very similar oscillatory responses swapping from s8050 to mpsa42 then mpsa06. Both mpsa had simliar capacitances and similar speed and both made the amp oscillate where s8050 dosen't.


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PostPosted: 24 Feb 2019, 03:50 
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Joined: 23 Feb 2017, 02:02
Posts: 544
Last time with regards having multiple pre amp rebuilds, transitors from china was more of a excuse in having bad schematic design and not accepting it.
I never had encountered a fake chinese to-92 yet.

TL431 does have more noise than geniune ones though but what can I expect with such low prices.


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