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  #1  
Old 15th February 2017, 09:14 PM
JohnG JohnG is offline
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Default Sonic Signatures of Volume Controls

After many hours investigating some DIY Active/Passive Preamp options.
It became apparent that either of these options will require a volume control.
At present I have read much about Stepped Attenuators,
Transformer Volume Controls, Autoformers and Potentiometers.
In a conversation with my friend and long term electronics engineer,
he claimed"many products have a Sonic Signature and many written views on the items performance are Subjective and heavily influenced by personal taste".
His view was that a very good quality and properly matched Potentiometer,
will offer a great performance. I believe he was also inferring that the way it
will increase volume is appealing to the human ear.
It would be great to hear further views on how a Volume Control has been witnessed to have a better or worse effect on a replay.
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  #2  
Old 15th February 2017, 09:43 PM
bikerhifinut bikerhifinut is offline
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Default Re: Sonic Signatures of Volume Controls

Oh what a treacherous path you are about to follow!
All I can advise is start off with a modest "ordinary" logarithmic potentiometer. This what I think your friend alludes to in that the resistance scale in the pot is not linear but the resistance increase as the wiper traverses the arc follws more or less a logarithmic progression which is very like the way the human ear perceives increases in sound levels.

Most never feel the need to progress beyond a tenners worth of "Alps" Blue, the good old RK27 pot. My take on this is that most of the subjective stuff is down to how well the pot is matched on each stereo channel where subtle imbalances in level as the control is rotated give an illusion of tonal imbalance.
I don't believe in "magic" at least not since i was about six!
I have had good results with switched attenuators too, again I think down to good channel matching.

Many on here swear by the "shunt" modification to volume controls. I swear at them, they do nothing for me at all and I can think of at least one reason why they aren't necessarily a great idea. But you won't know until you try it and at least all that particular trick will cost is the price of a couple of resistors.

My advice would be not to read so much and just start off with the standard potential divider control, by all means buy something like an Alps blue as they aren't expensive, you're only going to end up there to start with anyway.
Then decide if you want a simple passive or active preamp/buffer unit.

A.
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Old 16th February 2017, 12:06 AM
davebms davebms is offline
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Default Re: Sonic Signatures of Volume Controls

hello all.. err im lost , I think, be it passive or active, you will need a volume
control ? And YES (Subjective and heavily influenced by personal taste".)...
that's the good part off diy you can alter It . as bikernut says the alps is a very
good starting place (would recommend NOT ebay) I built a OTL headphone amp( I can, hear changes with headphones more,,,,going deaf?)pots,, they seem
to make a difference,, in the bijou otl ALPS good,, TOCOS good top end(not for me),,DACT my preferred, BUT not tried it in anything else
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Old 16th February 2017, 08:57 AM
bob orbell bob orbell is online now
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Default Re: Sonic Signatures of Volume Controls

John, stop fretting about such thing's and get the flipping power amps built, then let us know what input value they are, and we will help from there, you appear to be getting paranoid about nothing. BOB
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  #5  
Old 16th February 2017, 10:41 PM
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Ali Tait Ali Tait is offline
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Default Re: Sonic Signatures of Volume Controls

If you want a great pre for non foo money, buy a pair of the autoformers shown here for 200 dollars-

http://www.intactaudio.com/atten.html

One of the best bargains in audio IMO.

Obviously you will need a box and selector switch also, but if you are happy with a bit of DIY, this will make a world class pre for not a lot of outlay.
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Old 16th February 2017, 10:45 PM
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Ali Tait Ali Tait is offline
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Default Re: Sonic Signatures of Volume Controls

Here's the build of mine, I used a nice passive pre I already had-

http://theartofsound.net/forum/showt...ghlight=Slagle
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  #7  
Old 17th February 2017, 07:35 AM
JohnG JohnG is offline
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Default Re: Sonic Signatures of Volume Controls

Thank you for sharing
It is priority to get the 845 mono blocks complete, I have just recently funded the production of the second power supply.
Whilst I was waiting for the completion, I quite liked the idea of hearing how the forums users, who have swapped out volume controls noticed differences in their effect on a replay.
It was the autoformer reviews, that lead me to ask for others thoughts on volume controls in this thread.
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Old 17th February 2017, 10:07 AM
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Ali Tait Ali Tait is offline
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Default Re: Sonic Signatures of Volume Controls

It's certainly easily the best pre I've had in my system.
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  #9  
Old 17th February 2017, 12:57 PM
bikerhifinut bikerhifinut is offline
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Default Re: Sonic Signatures of Volume Controls

I'll echo Bob O, just get the power amps built and working well first. Don't worry about preamps etc until you need to.
Then just use a simple "pot in a box", buy an Alps Blue off matthew here, he won't over charge you and it'll be a "real one" (beware of Chinese eBay bargains here). I guarantee it will be easily good enough for you as its the Industry "standard" and is found in some very expensive commercial kit. And then if you go DIY on an active you already have your attenuator so thats a bit saved innit?
Actually for a simple "lash up" I wouldnt even bother with the box, just mount everything on a bit of veroboard and either use "flying leads" terminated in phono plugs or a couple of sets of PCB mount RCA sockets onto the perforated board.

Andy.
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  #10  
Old 22nd February 2017, 01:18 AM
A Stuart A Stuart is offline
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Default Re: Sonic Signatures of Volume Controls

Quote:
Originally Posted by bikerhifinut View Post
I don't believe in "magic" at least not since i was about six!
So now we all know why Tinkerbell is struggling on life support.
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