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Old 24th September 2010, 04:33 PM   #1
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Default 314159265358979323846264.... good rasons why?

314159265358979323846264.... good rasons why Papa should have a play with the A75.


Any comments? on this few came to mind.

1) because if any one can Nelson Pass can.


Would you like to se what nearly in 20 years can change ...
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Old 24th September 2010, 04:50 PM   #2
eLarson is offline eLarson  United States
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Mr. Pass's co-author (Norm Thagaard) had a go at an update to the A75 a few years ago. If memory serves (and it does not always) the changes were not revolutionary, but more like parts substitution.
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Old 24th September 2010, 06:29 PM   #3
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Tanks eLarson any link to get that info?
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Old 24th September 2010, 11:28 PM   #4
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Hmm, good reasons why the A75 should be updated or improved??

I'm not sure it should, it is a great amp just as it is.

That said, I wish I hadn't blown mine up so I could do some listening tests against my F5.

JJ
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Old 25th September 2010, 01:40 PM   #5
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Hi JJ sorri to hear that.
As you have a A75 could you give me any pointers on where to find links on Diagrams and modifications or even your personal experience construction notes.

I have the information from the Pass site A75 part 1 and 2.
And I am collating all I can get from the forum.

Ps (at work at present so I may be wrong) I believe that on the A75 there are same 30 Ho. resistors to ground few have rised this point any way to get rid of them?
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Old 25th September 2010, 09:59 PM   #6
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Quote:
Originally Posted by Bksabath View Post
314159265358979323846264.... good rasons why Papa should have a play with the A75.
Appropriate that you should pick an irrational number.

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Old 25th September 2010, 10:33 PM   #7
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Hi Nelson

Number may be more recognisable if you place a dot after the 3
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Old 26th September 2010, 01:13 AM   #8
eyoung is offline eyoung  United States
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easy as cake....

piE
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Old 26th September 2010, 01:50 AM   #9
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Bksabath-

I will definitely provide any help I can if you do build one. There are also several threads on the forum about the A-75, and there are many other members around who have built the amp.

I bought my boards from AudioXpress, but I they have been out of stock the last couple of times I checked.

Not sure about the resistors to ground. The schematics shown in the A75 articles are correct, and any resistors to ground on those schematics are necessary for various reasons.

JJ
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Old 26th September 2010, 04:25 PM   #10
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Tanks Jupiterjune

All the help I can get will be most welcome.

The reason for this tread is to put forward suggestions for reasons why Papa Nelson should have a stab at in proving the A75

Reading around I have found quite few comments on removing the 30Ho resistors from the output to ground believe they are necessary to reduce the DC offset to ground.

Maybe this would be a god improvement maybe especially if you have built one You have same more maybe much more valid points.

Another that came to mind is that there may be better new semiconductors to do the job.

In regard to my build of the A75 I will first Trying something more simple and I am at present collating information on the F5 Aleph X Aleph XJ.

I have found same good stuff burried under tons of info, EG I have in front of me 3 different drawings for the Aleph x supply voltages vary from 15+- to 24+-

Thats why I have started my other tread If you know where the good reliable information and drawings are please paste the links on that post.
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