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Old 28th April 2009, 11:31 AM   #281
sajti is offline sajti  Hungary
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And Fairchild have B selected groups...

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Old 29th April 2009, 11:48 PM   #282
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Quote:
Originally posted by sajti
You can get 2SC5242 from Fairchild as well. The direct order from the manufacturer means no problem with the fake transistors.

Sajti

Digikey has Toshiba's too but I'm going to give the ST's a try.
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Old 30th April 2009, 08:08 AM   #283
CECCO is offline CECCO  Italy
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Hello.

Can I use the a970 c2240 for the input stage and MJ15030,31 for the vas?
I even don't understand the use of LED's. Do they bring any benefit?
For the power I want to use tosh 5200/1943. These cost 1.6euro (10pcs) instead 2.1euro (10pcs) for the ST one's.
Plus, the Toshiba devices are "matched" by suffix ST don't.

Thank You.
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Old 30th April 2009, 08:19 AM   #284
sajti is offline sajti  Hungary
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I have very good experiences with NJW-s. The hfe matching is very close. And the Fairchild FJL4x15 is good too, with quite high hfe (150-200@250mA, O class)

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Old 30th April 2009, 04:23 PM   #285
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by CECCO
Can I use the a970 c2240 for the input stage and MJ15030,31 for the vas?
the 970 should make a good front end, particularly the BL grade.
The MJE15030/1 are good 8A drivers. They are not suitable for VAS or pre-driver duty.
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Old 9th May 2009, 10:10 AM   #286
CECCO is offline CECCO  Italy
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Is this a Class-A amplifier?
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Old 9th May 2009, 10:36 AM   #287
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by CECCO
Is this a Class-A amplifier?
have you looked at the schematic in post1?
ClassAB using the integrated diodes to generate a temperature compensated bias voltage.
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Old 9th May 2009, 01:14 PM   #288
CECCO is offline CECCO  Italy
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Quote:
Originally posted by MJL21193
[B]

Yes, it's true, lots of heat to get rid of. Yet, there are degrees - how much distortion is acceptable? Dropping the idle current down to ~80mA/device has the total dissipation at 50 watts and the distortion at 1k is still less than .01%. Choices...
This raises the question: is it worth this to eliminate global feedback? Will the benefits be heard or are they just assumed? Is global feedback that bad?
Surely, for quiet listening the fact that the amp will be effectively operating class A should be an improvement.

Why should the amp operate in class A?
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Old 9th May 2009, 01:25 PM   #289
AndrewT is offline AndrewT  Scotland
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it's ClassAB
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Old 9th May 2009, 07:14 PM   #290
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Quote:
Originally posted by MJL21193
2STA1962
Truly remarkable.

(John, if your XX's come close to resembling your avatar maybe we can still work out a deal afterall, whatever their residual mileage)
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