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motorised faders PWM?
Old 15th December 2010
Gear Nut

motorised faders PWM?


i wonder if anyone here knows how the high end motor faders in mixing desks are powered? Are they generally powered with PWM? i wonder approximately what frequency is ideal if they are?

any info would be great

: )
Old 15th December 2010
Lives for gear
Remeniz's Avatar

I can only comment on the Yamaha 01/02/03 mixers with motorised faders.

The faders are driven by a transistor bridge driver IC's and the output is variable voltage control.

PWM control would be a much better solution especially as the smooth tracks get gunked up over the years with hair/dust and I reckon PWM is used to drive faders on more expensive equipment.
Old 15th December 2010
Gear Nut

thanks! : )

PWM has more torque and accuracy , but when i have used pwm in the past on motors it is very noisy ( mechanically with a bbbbbzzzzzzz type of sound) i thought perhaps the neve and SSL desks use a particular frequency PWM or use clever insulation methods around the motor ? or maybe their faders are so smooth and nice that they can just use DC? i just had to post a question . : )
Old 16th December 2010
Lives for gear

There is a lot going on behind this question!
Faders for an 'all digital' desk have no serious worries about radiation of motor drive 'rubbish' so COULD use PWM and the 'best' frequency would be determined by the mechanics of the motor and the mechanical assembly. PWM can tend to run hot though so it needs to be quite 'intelligent'.
If it is a fader in analogue gear then it is usually preferable to use DC to reduce the possible interference although there are various means of drive and touch sensing used but this has to be properly 'integrated' into the gear. The PWM drive signal would have to be WELL above audio frequencies and then the audio paths need filtering to remove this / these frequencies.
Matt S
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