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Some differential audio mux questions

Category: Hardware
Product Number: ADG1407

On dual 15V supply, to make a 16:1 x 2 differential mux that specs well for pro audio, it looks like ADG1407 x 2 would be the best starting point.

Optimistic expectation is -115dB THD+N into 10K, which looks attainable with that part. Relevant bandwidth is 20Hz - 200kHz. Signals are 22dBu SE or 28dBu differential.

I’m a noob with muxes, so forgive my unfamiliarity. This is for rotary switch replacement. Let’s just say the end goal is the equivalent of a 4P16T rotary switch.

1. Are there reference designs for controlling multiple 8:1 x 2 muxes from a single encoder? I’d like to avoid cascading switches.

2. Igor mentioned in 2021 that y’all were working on a THD calculator for your switches and muxes. I’m not finding it with the other calculators. Does it exist?

3. It looks like complimentary parts for relay replacement and smaller scale switching (with similarly transparent audio results) are ADG1411, 1412, 1413. Am I on the right track?

  • Re: #1, I could extrapolate a schemo from any example where an encoder controls one mux through a portion of its travel, and another mux through another portion of its travel. I just don’t want to go in an over complicated direction straight off the bat.

  • A helpful suggestion, hopefully: It looks like the data sheet would be more user-friendly for audio if the data in Figure 24 were captured at 600Ω and 10KΩ, and included a 30Vpp trace. 100Ω load is a great worst-case reference but not so relevant in everyday use -- nobody's trying to put an analog switch between a discrete op amp and a step-up output transformer. Similarly, the crosstalk and off-isolation data of Figures 20-22 would be meaningful with a test circuit into 600Ω and 10KΩ, and in that case a 100kHz trace bandwidth would be just fine.

  • Hi,

    Thanks for your inquiry, I will look into this and get back to you asap.


  • I did figure out the flow, it is essentially this chicken scratch. It would be very helpful to see THD+N into 600 and 10K, and know the point on dual 15V supply where the THD takes off towards the heavens. It’s somewhere above 25Vpp, right? Say audio on the data sheet and these are the natural questions that arise. My application puts the differential drains into 100K fwiw, but there are other situations in which 10K is expected. And in the case of potentially using the 1411/12/13 for relay replacement type applications, standard audio loads and behavior into those are key data points.