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Old 16th December 2009, 08:42 AM   #21
wahab is offline wahab  Algeria
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MJL21193/21194 are somewhat rebranded MJ15XXX...slightly
improved 2N3055....
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Old 16th December 2009, 08:56 AM   #22
Eva is offline Eva  Spain
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Something to consider is that On-Semi transistors almost always have much higher capacitances than similar Japanese ones, even the high Ft ones. This may have to do with the lower Ft (again, even "high Ft" On-Semis don't have such a high Ft).

I don't know why capacitance is always a few times higher, maybe they just use bigger dies, or they need bigger dies for the same SOA, or their fabrication process results in higher capacitances, or just they don't optimize capacitances at all (I think the last option).

Several times I had to increase miller capacitance when replacing dead On-Semi (Motorola) MJE340&MJE350 VAS and pre-drivers by Philips ones (no other brand available) in order to make the amplifiers stable again. If I remember properly, the ones from Philips also had higher hFE (and probably 5-10 times higher Ft... Philips seems like the opposite example, they always seem to do everything with as little silicon as possible, Japanese seem to be in the middle )
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Last edited by Eva; 16th December 2009 at 09:00 AM.
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Old 16th December 2009, 11:23 AM   #23
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Quote:
Originally Posted by wahab View Post
MJL21193/21194 are somewhat rebranded MJ15XXX...slightly improved 2N3055....
"...slightly improved 2N3055" ??? But which 2N3055 ?? There are a wide range of different 2N3055, here some examples:
2N3055 Datasheet pdf - COMPLEMENTARY SILICON POWER TRANSISTORS - ST Microelectronics
and
2N3055 datasheet and Application Note, Data Sheet, Circuit, PDF, Pinout | Datasheet Archive

The 2N3055 from Semelab e. g. was prefer from certainly british high end audio products like Naim Audio (with custom specific type No). The transit frequency was much more higher than the usual value for this type (mostly 800 - 1000 KHz).
please read also this:
http://en.wikipedia.org/wiki/2N3055
and this
http://ieeexplore.ieee.org/xpl/freea...rnumber=960371

I would like to see one of RCA's first advertising photos and slogans from the time of introducing

Last edited by tiefbassuebertr; 16th December 2009 at 11:39 AM.
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Old 16th December 2009, 11:39 AM   #24
wahab is offline wahab  Algeria
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[QUOTE=tiefbassuebertr;2014907]"...slightly improved 2N3055" ??? But which 2N3055 ?? There are a wide range of different 2N3055
QUOTE]

yes, from 60V to 100V Vce...
Ft was extremely variable, most have 800K/1mhz Ft, the motorola
ones, aluminium cased, were 2.5 Mhz Ft...
for Vce, it seems the RCA ones were the more rugged...
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Old 16th December 2009, 01:13 PM   #25
BV is offline BV  Slovakia
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Quote:
MJL21193/21194 are somewhat rebranded MJ15XXX...slightly
improved 2N3055.
Compare datasheets (SOAR, Uceo,linearity- h21vs. Ic..) If it is "slightly" improved..Yes, MJL´s are not too fast, but fast enough for very good audio amplifiers, and they are very rugged and reliable, are not prone to parasitic oscilations, very stable, without base stoppers (better linearity) too.
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Old 16th December 2009, 01:24 PM   #26
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MJL's and MJ's suffer from a poor linearity compared to Sankens or Toshibas
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Old 16th December 2009, 01:32 PM   #27
wahab is offline wahab  Algeria
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Originally Posted by BV View Post
Compare datasheets (SOAR, Uceo,linearity- h21vs. Ic..) , are not prone to parasitic oscilations, very stable, without base stoppers (better linearity) too.

yes, stable because slow...
as pointed bobodioulasso, i prefer to stick with the trademarks
he name...sankens are particularly great...
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Old 16th December 2009, 01:52 PM   #28
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BV,
their pitiable speed gives a horrible high frequency performance and overall linearity, poisoning the whole audible range. (The beautiful measurements don`t show that).
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Old 16th December 2009, 02:11 PM   #29
BV is offline BV  Slovakia
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BV,
their pitiable speed gives a horrible high frequency performance and overall linearity, poisoning the whole audible range. (The beautiful measurements don`t show that).
Simply untrue, look at posted measurements, IMD19+20kHz and DIM100. Your ears and feelings tell us nothing about linearity.If You believe or not, high frequency performance and linearity show us measurements, THD10kHz (20kHz)and IMD and DIM, thrue various output levels.

Last edited by BV; 16th December 2009 at 02:15 PM.
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Old 16th December 2009, 02:36 PM   #30
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by bobodioulasso View Post
MJL's and MJ's suffer from a poor linearity compared to Sankens or Toshibas
That's actually true. In the old days when all you could get were 5MHz devices (even the Toshiba 2SD424) you had to use output triples if you wanted more than 100 watts or so or distortion would go through the roof. With the higher fT/linearity outputs and drivers you can get from Toshiba and Sanken now you can get away with just two current gain stages - all the way to 1200 watts or so. You just can't do that with the MJ's which don't have as good a beta linearity. And you don't "need" a triple at the more-normal 200W level anymore.

Of course, I'll still use a triple on anything over 55V rails myself, but I'm not trying to save 50 cents on a pair of TO-126 predrivers. Most manufacturers will up-end the universe trying to save those pennies.
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