Hi. I just added a MCP4231 8-bit digital pot to my headphone amplifier design. With some voltage dividers and blocking caps add a 2.5V offset, everything works just excellent and I enjoy using a rotary encoder instead of a regular potentiometer 🙂 I have a couple of questions though, I've payed no attention to distortion when choosing a digital pot, I just used one I had laying around. Is it possible for the MCP4231 to add audible distortion or should I have nothing to worry about? I'm also a little dissatisfied with the lowest audible level I can choose. I have a gain of 2.5 and an input signal of about 1V peak and the lowest pot setting is still quite loud actually. 1V/256*2.5*0.707=1.1mVrms which is really quite audible into sensitive headphones. Is there a way to get way more attenuation some how? There aren't that many higher bit digital pots to be found, but perhaps cascading two pots could work? An attenuation of 256^2 would be plenty I think 😛 Any ideas?
finer step volume controls aren't really the answer to bad gain structure
if you are using sensitive iem you could have as little as 200 mVrms drive some to 120 dB SPL
since many sources today are as much as 2 Vrms you really need low noise attenuation - not Voltage gain
someone should make audio output step down transformers optimized for these iem
cheaper is the "hiss buster" output resistor divider "power" attenuator
if you are using sensitive iem you could have as little as 200 mVrms drive some to 120 dB SPL
since many sources today are as much as 2 Vrms you really need low noise attenuation - not Voltage gain
someone should make audio output step down transformers optimized for these iem
cheaper is the "hiss buster" output resistor divider "power" attenuator
Hi,
Just add a (switcheable) passive attenuator at the input.
Or as jcx alludes to at the output, reducing the noise.
rgds, sreten.
Just add a (switcheable) passive attenuator at the input.
Or as jcx alludes to at the output, reducing the noise.
rgds, sreten.
I see now that there are several dedicated volume control chips that does exactly what I want. Thank you 🙂
you really should look into, try to understand "gain structure" for a better audio system
headphones bring this to the front because of their large range of sensitivities - you really have to design the amp for a restricted range of headphones or build in some method to switch system gains or attenuation in as much as 20 dB steps to accommodate even just dynamic headphones
headphones bring this to the front because of their large range of sensitivities - you really have to design the amp for a restricted range of headphones or build in some method to switch system gains or attenuation in as much as 20 dB steps to accommodate even just dynamic headphones
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