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Old 9th June 2003, 08:44 AM   #1
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Question X = bridged = push pull ? ...

Hi,


* In the manuals of the Aleph3/5 Nelson states that single ended classA is better because in push pull classA, it's like two guys sawing with one saw, not achieving perfect coordination.

When building a circuit in X configuration, isn't that introducing push pull ?


* The Aleph 3 current source, is it dynamic or not ?
In the manual I can't find anything about that.
It just says 2A.


* Is it sufficient in Aleph to have idle = 2 * output current ?

If the load is very high impedance and the load current is max. 50mA, is it ok to idle at 10mA ?


* Wouldn't a single ended DIY op amp always be better as a chip just because of being single ended classA ?

The chip op amps are always push pull
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Old 9th June 2003, 08:47 AM   #2
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Yes, the Aleph 3 uses a dynamic current source.
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Old 9th June 2003, 08:50 AM   #3
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Quote:
Originally posted by Freddie
Yes, the Aleph 3 uses a dynamic current source.

How much does the current change ?
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Old 9th June 2003, 08:55 AM   #4
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To answer part of your question, yes it is introducing an aditional factor but i'd be hesitant to really call it push-pull. Given that both ends are driven by N channel devices each in Single Ended configuration it's likely that we will do far less damage than the comparatively poor linearity of P vs. N channel devices plus when you consider the advantages of a balanced drive system, IMHO you end up quite a way ahead of push-pull amplification driving a single end of the load with the other end grounded.
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Old 9th June 2003, 09:03 AM   #5
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most of the alephs are set at roughly 50% so idle current is approx. 1/2 of the peak current the circuit can deliver.
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Old 9th June 2003, 09:38 AM   #6
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Quote:
Originally posted by AudioFreak
when you consider the advantages of a balanced drive system, IMHO you end up quite a way ahead of push-pull amplification driving a single end of the load with the other end grounded.
Moreover a push-pull is do with a single-ended signal wich drives a pair of non-inverting complementar devices .
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Old 9th June 2003, 09:46 AM   #7
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Quote:
Originally posted by AudioFreak
it's likely that we will do far less damage than the comparatively poor linearity of P vs. N channel devices

The linearity of P-fets is not so good like that of N-fets ?

The Aleph have P-fets in the input stage
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Old 9th June 2003, 10:36 AM   #8
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P channel devices are generally about 1/10 as good as their N channel counterparts and even P channel devices that are meant to be a match to their N channel counterpart are often quite a long way off being a good match for the N channel devices. The input stage is low power and again is single ended so does not incur as much of a penalty as would be the case with having P channels in the outputs. The real problem is with push-pull stages as the linearity of N channel vs. P channel is quite different so apart from the crossover distortion, you get quite different linearity for either side of the wave.
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Old 9th June 2003, 10:57 AM   #9
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Quote:
Originally posted by AudioFreak
most of the alephs are set at roughly 50% so idle current is approx. 1/2 of the peak current the circuit can deliver.

Thanks,

so can we say that the Aleph3 current source is basically biased 2A @ no signal

and

bias increases with signal to 4A @ full signal ?
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Old 9th June 2003, 11:06 AM   #10
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Quote:
Originally posted by Bernhard



Thanks,

so can we say that the Aleph3 current source is basically biased 2A @ no signal

and

bias increases with signal to 4A @ full signal ?

Yes that's approximately correct.
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