Accuphase AAVA Volume Control - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 10th July 2004, 01:10 PM   #1
EE is offline EE  Germany
diyAudio Member
Join Date: Oct 2003
Default Accuphase AAVA Volume Control

Has anybody ever tried to figure them out? I recently had an opportunity to hear an Accuphase C-2800 and I really liked the volume control: Feels as precise as a pot, but no mechanical wear, and the sound quality obviously was much better than all those Crystal / TI volume chips or the DAC approach.

What they do is V/I-convert the signal in 16 binary weighted currents, switch those currents, add them up and I/V-convert them back.

The C-2800 seems to be an all discrete device, but the lower models like C-2000 have all opamps except the output stage.

What do you think of this kind of volume control? Worth reverse-engineering it?
  Reply With Quote
Old 18th June 2007, 07:26 PM   #2
diyAudio Member
Scytales's Avatar
Join Date: May 2003
No thoughts ?
Ce n'est pas se donner que de donner ce qu'on voudrait Ítre. (Patrick Drevet)
  Reply With Quote
Old 18th June 2007, 07:35 PM   #3
mlloyd1 is offline mlloyd1  United States
diyAudio Member
mlloyd1's Avatar
Join Date: Feb 2001
Location: Northern Iliinois
from looking at the website brochures a while back, i thought it looked interesting also. however, i have no chance to hear one live to decide if the implementation was worth persuing.

  Reply With Quote
Old 4th September 2009, 12:02 PM   #4
pr is offline pr
diyAudio Member
Join Date: Dec 2002
Location: Germany
Default sample schematic


I tought about it a while and came to this solution. It is my guess and what I would start with. I have no clue how similar my solution is to the original.
I attached 2 files: a picture and a zip file containing a simulation file for LTspice and the model fot the jfets.
The parts used and the values are not especially chosen. So it is up to you to choose optimal sounding parts and values. The trick is, that the current summing stage U5 has an input potential of zero volts. Thus the V-I-converts are simple buffers with a resistor connected to the input of U5. For example the output current of branch 1 is voltage V1/R1 and the output current of branch 2 is voltage V1/R2. Both currents flow into the current summing point at the minus input at U5 and then they all together flow into R5, giving the output voltage, which hence is the I-V-converter. The JFETs are used as the signal switches. If their gates are 0V, they are on, if tey are negative, they are off.
Only 4 instead of 16 branches are shown but you can add the missing 12 easily.
Each branch has got it's own switch. Only switch 4 is switched on.
If you want to change the volume, change the settings of the switches.

Have fun.

Attached Images
File Type: jpg aava.jpg (79.8 KB, 497 views)
Attached Files
File Type: zip (2.6 KB, 105 views)
  Reply With Quote
Old 31st March 2012, 02:49 PM   #5
diyAudio Member
Join Date: Apr 2005
Location: -

This seems to be very old topic but just for curiosity, has anyone tried this? Or anything similar?

Based on pr's simulation model, I would use T-switch structure to replace the single switch for better off-isolation. And preferably go for fully balanced version. In addition it would require some sort of logic to recognize zero crossing from input signal, otherwise there will be annoying noises when switches operate.

I've been thinking about building pre amp with "an exotic" volume control and found Accuphase's AAVA documentation for a some time ago. Something like this combined with input selector and AV-loop would solve problems with two sets of equipment (HT and stereo) but only one pair of speakers.
  Reply With Quote
Old 31st March 2012, 04:03 PM   #6
jaycee is offline jaycee  United Kingdom
diyAudio Member
Join Date: Apr 2004
Location: Norwich, UK
Originally Posted by EE View Post
What they do is V/I-convert the signal in 16 binary weighted currents, switch those currents, add them up and I/V-convert them back.
Smells exactly like ADC/DAC to me!
  Reply With Quote
Old 31st March 2012, 04:27 PM   #7
qusp is offline qusp  Australia
diyAudio Member
qusp's Avatar
Join Date: Oct 2009
Location: Brisbane, Australia
Originally Posted by jaycee View Post
Smells exactly like ADC/DAC to me!
whats that saying 'a Rose by any other name would smell as sweet'
  Reply With Quote
Old 31st March 2012, 08:04 PM   #8
diyAudio Member
Join Date: Apr 2005
Location: -
Well, I wouldn't say it's a DAC nor ADC. Operating principle of course is somewhat digital, but signal is not converted from one domain to another.

I have been looking for solution that could be used also with DAC without compromising the signal quality. Digital multiplier inside the DAC chip or in the DSP is not the optimal solution and neither is the traditional analog methods. I've been using those PGA chips for some time and looking for something new to experiment with.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Volume control on DVD player remote. Lose resolution at low volume? Circlotron Digital Source 2 10th June 2011 07:20 PM
i need preamp schematics w/o tone control or volume control hernanstafe Parts 7 30th January 2008 03:12 AM
The remote control paratactic volume control audio-gd Solid State 33 7th June 2007 11:16 PM
Accuphase Tone Control Needed robinson_guitar Solid State 0 10th January 2007 06:27 AM
remote control motorised control for volume pot/knob CharlesY Parts 0 25th July 2005 11:12 AM

New To Site? Need Help?

All times are GMT. The time now is 10:25 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2