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Article: Variable Gain Volume Control


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The is a nice series to show here on AS.  Gets me thinking about volume controls and the plethora of places we can often find them in the computer audio signal path.  Software players have them; dacs can have them; preamps, of course, are the classic place they exist...and even some power amplifiers have them (gain switches, etc).  There are philosophies that each support a different place to do them correctly.  For example, digital attenuation with upsampled material, throwing away "unnecessary bits" that do little or no harm!  Bypass this or that volume control...are we really bypassing, or are we paying even a small price.  Argh.  It might make sense (or maybe it's already out there; haven't searched) to have a thread discussing these different ideas of where to attenuate the most effectively. 

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I love Ayre and I particularly enjoy my VX-R/Twenty amp, however for less cost, I decided to pass on the KX-R/Twenty Preamp in favor of upgrading my MSB Premier DAC to an MSB Reference DAC with the optional preamp constant impedance passive volume control. It also includes analog inputs so completely negates the need for an external preamp as my only other source is a turntable.

 

Hoping that Ayre releases some newer and innovative high end components that compete with this or surprise us in other ways. A great volume control is *necessary* but the KX-R/Twenty is 6-7 years old or more and Ayre’s needs to innovate to catch up or even remain competitive in the market. 

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So many "state of the art" approaches to address this Achilles' heel of audio - Icon now making reasonably priced high quality autoformer attention, continual refinement of digital volume control, variable gain technology by Ayre (I believe also used by Metrum), and of course the "classic" preamp strategy using active tube or transistor gain with downstream analog attenuation.  Would be interesting to see a head-to-head comparison of these technologies at some point, though suspect that the answer to "which one is best" will likely be, "it depends."

 

 

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  • 4 weeks later...

Is this an attenuator (active resistor, JFET based) at the output stage of the amp? Or is it in the input stage of the amp? Or is this actually acting as a gain control directly on the amp?

 

Also, am I looking at the correct references: https://en.m.wikipedia.org/wiki/Voltage-controlled_resistor

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1 hour ago, manueljenkin said:

Is this an attenuator (active resistor, JFET based) at the output stage of the amp? Or is it in the input stage of the amp? Or is this actually acting as a gain control directly on the amp?

 

Also, am I looking at the correct references: https://en.m.wikipedia.org/wiki/Voltage-controlled_resistor

Let’s ask @Ryan Berry from Ayre. 

Founder of Audiophile Style

Announcing Polestar | Quick Community Reviews and Ratings

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On 9/19/2020 at 1:38 PM, rhmmmm said:

I love Ayre and I particularly enjoy my VX-R/Twenty amp, however for less cost, I decided to pass on the KX-R/Twenty Preamp in favor of upgrading my MSB Premier DAC to an MSB Reference DAC with the optional preamp constant impedance passive volume control. It also includes analog inputs so completely negates the need for an external preamp as my only other source is a turntable.

 

Hoping that Ayre releases some newer and innovative high end components that compete with this or surprise us in other ways. A great volume control is *necessary* but the KX-R/Twenty is 6-7 years old or more and Ayre’s needs to innovate to catch up or even remain competitive in the market. 

 

Hey Rhmmmm, appreciate the response.  In all reality, we're still waiting for someone to catch up to our 6 year old design. :)  But seriously, when we last upgraded the KX-R, back in 2014, we weren't sure if there was a way to make it any better.  The KX-R has a special story as Ariel mentioned in a PWA video...when Charley and he finally nailed down the design of the original KX-R, we were left with a preamplifier with 0.00X distortion with zero feedback in the circuit.  Charley was so excited, he called up John Curl to tell him what he was able to do and John couldn't believe him!   

 

It's hard to make lightning strike twice...the KX-R was largely considered the best preamplifier on the market by almost anyone that had heard it and improving it was not going to be a small task.  We were really lucky when we started playing around with the diamond circuit design and the AyreLok power regulation we're using today.  After getting the first prototypes done, Charley and I looked at each other and knew we had something almost immediately.  It's pretty rare in our design process for that to happen and the KX-R Twenty was born.  

 

My point is that newer is often not necessarily better.  A great example are the Toshiba JFETs Ayre uses in its circuit design to this day.  The parts were discontinued by Toshiba over a decade ago, yet there has yet to be a replacement anywhere in the market that can touch what they are capable of.  Still, we always keep looking for new ways to do things or further improve our greatest achievements.  We're as much hobbyists as anything and love finding better ways to do something.

 

Cheers,


Ryan

President

Ayre Acoustics, Inc.

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10 hours ago, manueljenkin said:

Is this an attenuator (active resistor, JFET based) at the output stage of the amp? Or is it in the input stage of the amp? Or is this actually acting as a gain control directly on the amp?

 

Also, am I looking at the correct references: https://en.m.wikipedia.org/wiki/Voltage-controlled_resistor

 

Hi Manuel,

 

The VGT is a variable gain amplifier stage, so closest to the third option. 

No, a voltage controlled resistor is effectively what is happening in a JFET, like those we use in our products, but they are not part of the volume control for us.  The VGT uses a mechanical switch and motor to select different resistors for each volume level, which changes the gain stage's output level.  It's tricky to work with as it has quite a few moving parts that need to work perfectly together to behave properly...one of the reasons other companies tend to avoid a switch like this.

 

Cheers,


Ryan Berry

President

Ayre Acoustics, Inc.

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On 9/22/2020 at 9:27 AM, all300b said:

So many "state of the art" approaches to address this Achilles' heel of audio - Icon now making reasonably priced high quality autoformer attention, continual refinement of digital volume control, variable gain technology by Ayre (I believe also used by Metrum), and of course the "classic" preamp strategy using active tube or transistor gain with downstream analog attenuation.  Would be interesting to see a head-to-head comparison of these technologies at some point, though suspect that the answer to "which one is best" will likely be, "it depends."

 

 

 

Indeed it's a problem area ... decades ago virtually everything had its SQ slugged by inferior implementations - though a high end Yamaha CDP I started with had a digital volume control that was well enough done that its presence was inaudible. I strongly suspect any analogue contraption, and nothing irritates me more than being able to pick the steady loss of quality as the contacts of the mechanical parts degrade with time - refreshing the contact area is not a solution!

 

Solid state switching, or digital attenuation are acceptable solutions, IME.

Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Over and out.

.

 

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On 10/15/2020 at 8:29 AM, Ryan Berry said:

 

Hey Rhmmmm, appreciate the response.  In all reality, we're still waiting for someone to catch up to our 6 year old design. :)  But seriously, when we last upgraded the KX-R, back in 2014, we weren't sure if there was a way to make it any better.  The KX-R has a special story as Ariel mentioned in a PWA video...when Charley and he finally nailed down the design of the original KX-R, we were left with a preamplifier with 0.00X distortion with zero feedback in the circuit.  Charley was so excited, he called up John Curl to tell him what he was able to do and John couldn't believe him!   

 

It's hard to make lightning strike twice...the KX-R was largely considered the best preamplifier on the market by almost anyone that had heard it and improving it was not going to be a small task.  We were really lucky when we started playing around with the diamond circuit design and the AyreLok power regulation we're using today.  After getting the first prototypes done, Charley and I looked at each other and knew we had something almost immediately.  It's pretty rare in our design process for that to happen and the KX-R Twenty was born.  

 

My point is that newer is often not necessarily better.  A great example are the Toshiba JFETs Ayre uses in its circuit design to this day.  The parts were discontinued by Toshiba over a decade ago, yet there has yet to be a replacement anywhere in the market that can touch what they are capable of.  Still, we always keep looking for new ways to do things or further improve our greatest achievements.  We're as much hobbyists as anything and love finding better ways to do something.

 

Cheers,


Ryan


My point is that this is solving a problem I simply don’t have. I don’t know anyone else that has a problem that is solved by a $25k 8-input analog preamp. 
 

I need a high quality volume control and I have 2 sources. One that is digital and itself has a variety of digital inputs, and my ARC phono pre has 2 inputs. I simply don’t see the value in paying $25k for a volume control and 6-7 extra inputs plus taking up unnecessary rack space when the dollars can be used more wisely somewhere else. 
 

The innovation and market catch-up I refer to and suggest to Ayre in my original post is in digital and other green/white space you currently aren’t covering or aren’t covering as well as competitors. For example, where are the highest-end digital Ayre “R” components? Why not use the great volume control and other tech in a newer flagship component that addresses problems people have *now* in the streaming age? You said yourself the KX-R Twenty hasn’t been updated since 2014. Everyone is staying at home right now and the stock market is up, the time is right for a new, innovative product drop in the *highest-end* Ayre range. 
 

 

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