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Old 22nd February 2006, 10:37 AM   #1
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Default Aleph Phase Inverting / non inverting

It may see an odd question but can anyone confirm if the Aleph has an inverting or non inverting output referenced to the input signal?

Macka
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Old 22nd February 2006, 10:59 AM   #2
Stefano is offline Stefano  Italy
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Hi!
Since his output stage isn't a follower it must be non-inverting (I think).
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Old 22nd February 2006, 12:04 PM   #3
Bobken is offline Bobken  United Kingdom
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Hi,

Surely this is governed by the number of gain stages in the amp, each one providing a nominal 180 Deg. shift or 'reversal'.

If so, Aleph 30 with 2 stages is non-inverting, but some of the earlier Alephs (IIRC, but I cannot access the schematics now to check) had 3 stages, in which case they would be inverting.
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Old 22nd February 2006, 12:40 PM   #4
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Arr . . .
Aleph is too complicate for me . . .
Anyhow, if I see the feedback line from the output, it is the non-inverting feedback. The output signal has the same sign with the input signal applied to the non-inverting input.

jh
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Old 22nd February 2006, 01:14 PM   #5
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The amp, taken as a whole, is non-inverting.
The output stage is inverting. The front end, being a differential, can be hooked up to be either inverting or non-inverting. In this case Nelson chose the inverting hookup.
The signal comes in, inverts going through the front end. Now it's "upside-down." Then it goes through the output stage and gets flipped once more, making it "rightside-up."

Grey
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Old 22nd February 2006, 01:56 PM   #6
Bobken is offline Bobken  United Kingdom
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Default Grey's the man who will know!

Hi Grey,

Is my above recollection right that one (some?) of the earliest Alephs had 3 amplifying stages, and were accordingly inverting?

I had only downloaded the A30 details, and, of course, Nelson has needed to remove the other circuits from prying eyes.

Regards,
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Old 22nd February 2006, 02:33 PM   #7
MikeW is offline MikeW  United States
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http://www.passdiy.com/pdf/mos.pdf
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Old 22nd February 2006, 03:02 PM   #8
Blues is offline Blues  United States
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Default Re: Grey's the man who will know!

Quote:
Originally posted by Bobken
Hi Grey,

Is my above recollection right that one (some?) of the earliest Alephs had 3 amplifying stages, and were accordingly inverting?
Regards,
Bob,

His 1st gen Alephs like the 0 and 1, although having three gain stages is also non-inverting as the 3rd stage is a bunch of paralleled followers and does not invert the output of the 2nd stage. The input is a diff pair with output taken from the drain inverts then the 2nd is a voltage gain stage will revert back to the same phase as the input signal.

Allan
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Old 22nd February 2006, 03:32 PM   #9
Bobken is offline Bobken  United Kingdom
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Hi Allan,

Thanks a lot for this clarification. I was right about the 3 stages then, but my memory let me down on the topology details.

Tries hard, could do better, only 5/10!

Nelson spoilt us all, maybe for too long, and I guess I took it for granted that these details would always be available on his site.

It was a really sad day when I saw that Nelson was forced to remove his schematics, but I fully understand why he did this.

I just wish I had downloaded them all ages ago, when they were available.

Regards,
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Old 22nd February 2006, 07:01 PM   #10
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Thanks guys for all your replies.

Macka
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