Technique behind Aleph X0.2 Volume Control

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rsbay

Member
Joined 2004
rstaudio.de
Hello,

has anyone an idea how the volume control in the new Aleph X series preamplifiers is working. I saw a picture in a German audio magazine and I noticed that Nelson switch the resistors with semiconductors. In a first step this is very easy to do - there exist a lot of semiconductor switches on the market - but I expect to get a real good volume control you need more like that. How is the volume control made ?

Regards

Ralph
 
I

Ian Macmillan

Member
Joined 2002
Even if they did I am not sure they would share it. This would be Wayne's masterpiece and the technique used is part of a long overdue patent application and until it is granted it cannot be shared. That said, Nelson did throw down the gauntlet some while ago when he suggested that we try and reverse engineer it. Curiously nobody has taken up this challenge to my knowledge.
 
moamps

moamps

diyAudio Member
Joined 2002
moxtone.com
Ian Macmillan said:
.. Nelson did throw down the gauntlet some while ago when he suggested that we try and reverse engineer it. Curiously nobody has taken up this challenge to my knowledge.
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You tease! :devilr: There was no challenge. There is a special challenge opening ceremony first when Nelson waves his wand :wiz: and offers a free Sponge Bob T-shirt (alternatively, pink flamingo slippers) for the winner. :clown:

Regards,
Milan
 
I

Ian Macmillan

Member
Joined 2002
moamps said:


You tease! :devilr: There was no challenge. There is a special challenge opening ceremony first when Nelson waves his wand :wiz: and offers a free Sponge Bob T-shirt (alternatively, pink flamingo slippers) for the winner. :clown:

Regards,
Milan
Click to expand...

Not so, Nelson posted some while ago...

"If you want a truly fantastic semiconductor-based attenuator,
back engineer the volume control from the X series preamps,
which uses bipolar switches.

It outperforms the other stuff we've seen by a factor of about
10 in every parameter, and was developed by Wayne, who
has a patent pending on it."

I take this to be a challenge. :)
 
I

Ian Macmillan

Member
Joined 2002
Nelson Pass said:
Not much of a challenge since anyone who wants to can take
one apart. Of course you might have to buy one to do
it. Also, it's all SMT so get yourself a microscope.

:cool:
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I hadn't appreciated you meant it so literally - I thought you were challenging the DIY community to come up with something like Wayne's idea based on the various crumbs already scattered. Personally I think it would be much more fun even though it is unlikely that we would arrive at the same result (or maybe not arrive at all).

Taking one apart only tells so much. OK, so one can duplicate the circuit but that does not necessarily give much insight as to how it works. The latter is more intersting in my view although building one would be fun too.

I already bought an X2.5 (great preamp) but so far I have resisted the urge to take it apart. In any case I wouldn't be comfortable with sharing anything I learnt in this forum precisely because of the patent fiasco. I'm rather hoping that you will share the 'secret' when you are ready, presumably when the patent is granted.
 
BrianDonegan

BrianDonegan

Member
Joined 2004
twistedpearaudio.com
In any case I wouldn't be comfortable with sharing anything I learnt in this forum precisely because of the patent fiasco. I'm rather hoping that you will share the 'secret' when you are ready, presumably when the patent is granted.
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Here here.

However, I don't think I could avoid at least taking one apart if I owned one. Just too much to marvel at ;)
 
G

gl

Member
Joined 2003
NP has dropped a number of crumbs on this subject. One of the most interesting was that the volume control was a shunt and that it is not connected to the signal directly (IIRC).

I remember pondering this at the time and wondering if perhaps resistors 42 and 43 from Fig 1 of the SuSy patent 5,376,899 could be the shunts NP was referring to. The description of them in the patent seems consistent with this thought. Anyone?

Graeme
 
I

Ian Macmillan

Member
Joined 2002
gl said:
NP has dropped a number of crumbs on this subject. One of the most interesting was that the volume control was a shunt and that it is not connected to the signal directly (IIRC).

I remember pondering this at the time and wondering if perhaps resistors 42 and 43 from Fig 1 of the SuSy patent 5,376,899 could be the shunts NP was referring to. The description of them in the patent seems consistent with this thought. Anyone?

Graeme
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I don't think so. Practical realisations of the patent do not use said resistors and IIRC NP also said that resistors wandering off to ground in general are a bad idea. I prefer a different crumb (perhaps all these were thown out to confuse us) along the lines of employing a shunt attenuator at the virtual ground of a suitable active input. The signal level here is low which makes it easier to employ an active switch based on a semiconductor.

I'm also intrigued that bipolars are apparently preferred in Wayne's masterpiece as FETs look the more obvious choice. Perhaps this is down to a different consideration such as size or cost?
 
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