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Old 31st March 2003, 10:46 PM   #51
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yes thats the one
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Old 2nd April 2003, 05:29 AM   #52
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I cannot sent a paper to you until will get your answer on my private message with your email
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Old 4th April 2003, 01:47 AM   #53
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yes I did build the amp but I could only get one channel working inthe meantime I have concentrated on the aleph x.re the out put transistors,the authers have this to say,A problem with power transistors driven by a current source isthat there is no turn-off resistor for them.Under high-frequency,high-amplitude drive there will be a tendency for the effective bias current to rise dynamically.By useing HF power transistors with an ft of 80mhz, This bias current rise is reduced to 60% at 20khz at full drive.
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Old 4th April 2003, 02:38 AM   #54
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Ampman,

I am aware of that comment, ie., the requirement for 80MHz transistors in order to keep the bias stable. But the 2SC3281(5200) and 2SA1302(1943) pair are only 30MHz devices. Hence, my question - was the amplifier stable in long term operation and what about the sonics?

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Old 4th April 2003, 10:09 AM   #55
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Ampman,
How big is this effect? Say the dc bias current is 50mA. If you then output 20KHz into 8 ohms, how much does the bias increase with, say, 30MHz ft transistors? How do you differentiate the bias increase due to slow turn-off effect from thermal changes? How much %change in effective bias matters?
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Old 4th April 2003, 10:57 AM   #56
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I'm afraid I cannot anwser your question's as I have'nt got astereo pair working and secondly I'm not an EE. anybody care to put mosfets on the output.
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Old 7th April 2003, 03:32 PM   #57
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Ampman,

Don't worry about a STEREO version of the amp. That one channel that you have working, that is the one in question. Just let us know if the amp works stable for a relatively long time driving a nominal speaker load.

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