SQN 4S Series 3a Field mixer, and Attenuation cables

My new field audio kit

My new field audio kit

Recently, I added a field mixer to my collection of audio gear. I’m looking at getting more into audio production for video, and figured a field mixer was a very handy place to start. When this mixer came up on eBay, it peaked my interest. It was packing quite a bit of extras for a pretty good price. I ummed and Arred, before giving in, and buying it. Along with the mixer the extras included the bag, a break away cable, a pair of Sony headphones that look like they are as old as the mixer, and a few XLR cables. Basically an instant field audio kit. WOOT!

 

Attenuation cables

As you might be able to see in the picture, I have teamed up the mixer with my Zoom H4n, and I’ve been working on the best way to link the two devices.

The easiest way is XLR out of the mixer, into XLR of the Zoom, but due to the Zoom’s limitation of not accepting line level inputs, this connection has to be a mic level one, and I end up having to turn up the Zoom’s preamps quite a bit to get the levels where they should be. This isn’t optimal, as it introduces a lot of noise back into the recording, which is precisely what I’m avoiding by going with a mixer / recorder combo.

Best results I’ve gotten so far is coming out of the mixer line level, and attenuating the levels down until they are at a level the Zoom H4n can handle. I’m still going into the Zoom as a mic signal, but by choosing an appropriate level attenuator,  I can set the Zoom’s input levels much lower than using the mic outputs of the mixer (with the -30db cables, I can set the Zoom’s inputs to 20, instead of the 70 or 80 it’s at coming out mic level)

I messed round trying to find something that worked, scouring the internet for attenuator circuits. There is quite a lot out there that want to teach you how to work out your own values for attenuators, but it was rather difficult to find a straight forward circuit that says “Use X and Y resistors for an attenuation of Z”. Eventually, I found this Proharmonic article, which was nice enough to give some clear figures for attenuators.

 

a -30dB pad schematic

This is my rendition of a U bridge attenuator. For other values, please check out their article, linked above.

 

 

 

Comparison

To get a sense of how it performs, here are a couple of samples:

I hope this has been helpful to people out there. I’m off to record myself talking about nothing for a while, until I can find something more interesting to record.

Cheers,
Matt.

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