digital volume control
anyone implimented a digital (or other SS) volume control in their tube amplification? I'm thinking it would provide a relatively simple and clean faceplate solution and easily interface with remote control. Especially like the look of the IC based solutions eg Maxim or similar. Comments please.
DS1666 with push buttons. About to do it with a rotary encoder.
Not as bad as i anticipated. Better than cheap pots and at least no opamps inside. Should be easy to integrate a remote. And ARC uses it in their REF preamps.
6 relays, 12 resistors, one uln2001 and a microcontroller. gives 64 steps and I've picked the resistors for 1 db steps. Could easily change the attenuation per step and increase to 128 or even 256 steps if I wanted. Microcontroller is a BasicX24, but could be a pic instead. gonna use buttons for vol up and down, but could easily use a linear variable resistor connected to the microcontroller ADC to adjust volume too.
Do you mean like this? This is an Aikido preamplifier (preamp on the left, power supply on the right) with a Dantimax remote control system.
very nice solution scott - sorta raises the bar on my expectations! Yeah, I aslo considered relays and resistor networks, but it seems a lot of additional effort and a big opportunity for Mr StuffUp to enter the picture. Maybe at a later date! Thanks for the DS1666 solution - looks like the sort of thing I was after. Cheers all.
I get the Dallas / Maxim Engineering Journal and Design Guides sent to me in my day job.
3 more to look at (their descriptive prose, my comments):
"Simplest Pushbutton Interface Controls Audio Volume and Balance" - MAX5457
2 independent 10K Ohm potentiometers, will need buffer to drive that impedance
32 tap audio taper, steps of 2dB
UP, DOWN, MODE, MUTE(-90dB) Push Buttons
MODE toggles between Balance and Volume, there is a LED driver to indicate the mode.
Shutdown pin (active low) - stores last wiper position.
Same thing with separate Volume and Balance Up Down switches is MAX5456
"Push Button Audio-Control IC Mixes Two Independent Stereo Sources" - MAX5406
VOL UP/Down Switches
BALANCE L/R Switches
BASS UP/DOWN Switches (external Cap to set operating freq)
TREBLE UP/DOWN Switches (external Cap to set as above)
"AMBIENCE" Switch (artificially "enhances" stereo separation)
50K Input Impedance
32 step audio taper, 2dB per step
Pseudo Stero for Mono Sources
Sub Woofer Output
Shutdown store last Wiper Settings.
"Rotary Encoder IC Controls Volume and Balance without uC" - MAX5440
Integrated low power <0.003% THD Buffers
5 segment LED Setting Indicator shows Volume or Balance
-12dB Power on Reset
32 Tap Audio Taper
Surprising suggestions Gingertube: all seriously lo fi.
A lot of people use the one i link below, myself included.
A copy of the (discontinued) Wolfson WM8816.
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