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Old 16th December 2009, 05:36 PM   #41
wahab is offline wahab  Algeria
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Quote:
Originally Posted by AndrewT View Post
I have not even bothered to look at the datasheet, but I will guarantee that this integrated Darlington will not perform as a well as a pair of Darlington connected discrete BJTs, over a range of realistic output currents.
how can you be so sure?...without looking at the datasheet?
the current figures i give are from sanken, the manufacturer..
seems that for you, what you don t know don t exist..

these devices are 50 mHZ Ft....
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Old 16th December 2009, 05:41 PM   #42
wahab is offline wahab  Algeria
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MP1620 Datasheet pdf - Transistor De Puissance De Silicium De Type De Moule - Sanken

MN2488 Datasheet pdf - Power Transistor - Sanken

for those interested in good devices...
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Old 16th December 2009, 05:48 PM   #43
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Quote:
Originally Posted by Lumba Ogir View Post
Juergen,
Moreover, data sheets specifications do not signify sonic properties, but 80MHz is more promising than 4MHz. The general bandwidth / linearity relationship is known.
This is right.
But on the other hand Mr. Nelson Pass don't use such 40MHz-80MHz BjT devices neither in the Threshold aera nor in the passlabs aera. He use only Motorola BjT parts in the Threshold area and in the passlabs aera only power MOSFETs (instead expensive high Ft BjT's) from IRF. Also by the currently models, where are inside PP instead single ended output stages.
And as I know, nevertheless there are nothing other Class-A solid state amp model with 80 MHz BjT devices inside, that clearly do outperform the models from "X" and "XA" series, even not the legendary 400A and 800A with slow Motorola BjT's.
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Old 16th December 2009, 05:53 PM   #44
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Quote:
Originally Posted by wahab View Post
how can you be so sure?...without looking at the datasheet?
the current figures i give are from sanken, the manufacturer..
seems that for you, what you don t know don t exist..

these devices are 50 mHZ Ft....
He is right. At 50MHz transition freq, the gain is down to one. Starting at min maybe 5000 at DC. So you can easily see that at higher freqs the gain starts to drop very quickly. Discrete darlingtons can have much flatter gain versus freq curves. Only some specialized integrated darlingtons come close but don't make it.

Edit: the data sheet doesn't show gain vs freq curves. That tells me enough ;-)

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Old 16th December 2009, 06:01 PM   #45
wahab is offline wahab  Algeria
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Originally Posted by janneman View Post
He is right. At 50MHz transition freq, the gain is down to one. Starting at min maybe 5000 at DC.
Edit: the data sheet doesn't show gain vs freq curves. That tells me enough ;-)

jd
yes, i know it...the thing is that the -3db point is not at dc....
if you had read the datasheet, you would have see that there s
3 FLAVOURS of the transistors, gain given for 7 A collector current..
mini 5000
mini 6500
mini 15 000
the higher grade should do it..
i think that at 50khz, it should be enough..
these value of current gain are sustained in a range
largely exceding the audio band...
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Old 16th December 2009, 06:09 PM   #46
wahab is offline wahab  Algeria
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here the datas of their little brothers, limited to 8 A;;
the ft vs current is given by the graphs...
Attached Files
File Type: pdf 2SB1587.pdf (30.0 KB, 98 views)
File Type: pdf 2SD2438.pdf (29.5 KB, 61 views)
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Old 16th December 2009, 06:11 PM   #47
BV is offline BV  Slovakia
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2AndrewT
Quote:
Into 4 ohm speaker load this demand can rise to around 30Apk.
This cannot be met from a two stage output EF not even with double complementary pairs in the final stage.
It can, in measurements I posted in this thread ( post #14) You can find results for 200W/4ohms from two stage EF output with doubled output devices, all ONsemi´s (drivers MJE15032/33, output 2xMJL21193/21194). VAS current about 8mA. Dual slope protection in output included, most of distortion is originated from this protection (close copying SOAR).

Last edited by BV; 16th December 2009 at 06:16 PM.
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Old 16th December 2009, 06:26 PM   #48
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wahab,
55MHz@2A, Cob=95pF@10V, that´s pretty impressive for an integrated Darlington pair. Supreme Japanese technology...
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Old 16th December 2009, 06:35 PM   #49
wahab is offline wahab  Algeria
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Quote:
Originally Posted by Lumba Ogir View Post
wahab,
55MHz@2A, Cob=95pF@10V, that´s pretty impressive for an integrated Darlington pair. Supreme Japanese technology...

yes, lumba, i was stunned, they really do the things more than well..
far from the dreadfull TIP14XX and other motorola...
sanken is not onsemi, for sure..

by the way, those who advocate that the FT is not enough are simply
missing an important point : if 30 A peak are to be supplied to the speakers,
it s ONLY the WOOFER which will see this current, so at a low frequency, where the beta is at his higher value...
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Old 16th December 2009, 06:44 PM   #50
BV is offline BV  Slovakia
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Quote:
if 30 A peak are to be supplied to the speakers,
it s ONLY the WOOFER which will see this current, so at a low frequency, where the beta is at his higher value...
For full range amplifier with e.g.3 way box??? Amplifier must deliver high current for woofer, but in the same time superimposed high frequency signal. It si only mometary voltage at output and current what countns
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