Mixing it up for Maximum Meandering

 

 

 

 

 

 

 

During my operating periods with my portable operation in Concord, I am often listening to
multiple receivers at one time, be it dual-RX with the Yaesu FT-1000mp and/or the ICOM-7000
(to include SWL'ing) and/or various SDR (Software Defined Receiver) websites to get a 2nd listen
on one of the frequencies already being monitored.

What makes it all work is a $25 RockVille 8-channel (4-stereo device) mixer with an internally
added $13 4-watt stereo amplifier kit, amplifying the mixed output to run either a set of powered
multi-media speakers (with sub woofer), a dual-input Yaesu SP-6 speaker or wireless "Own Zone" headsets (one transmitter, multiple receivers).  In a previous blog (Radiosport: Learning about Learning), I discussed the problem of "ground loops" sneaking into a complex configuration;
the RockVille keeps the signals apart, and yet is not immune to ground loops.

Prior to starting this Blog entry the above mixer was distorting and breaking into spontaneous oscillation.  A couple of hours on the repair bench identified the POOR solder job I DiD when embedding the 4-w Stereo Amp inside the mixer box.  Coincidentally, since re-installing the
RockVille mixer, the ground loops seem to have all disappeared.

 

 

 

 

 

 

 

 

 

 

 

To make switching things around easier, as you can see, all cables leaving the
RockVille mixer are specifically labeled (CH# and L/R).  Also notice that low-end
audio mixers tend to offer up 1/4" phone jacks, requiring for WQ6X use, an RCA
to phone plug adapter for each of the 8 audio channels.

 

 

 

 

 

 

 

 

 

 

 

The original scribbles made way to numerous experiments resulting in the updated
layout shown in the above notes.  Because this is not a "professional" installation,
use of RCA plugs is actually a better choice than the fancier (and more expensive)
XLR plugs.  RCA cables are easier to convert to/from 1/8" jacks than the XLR approach. 
Then again, XLR cabled systems have a significantly less failure-rate, compared to RCA
cables (with no locking mechanism).

With all of the above equipment configuration enhancements, it would seem that we now have
"the best of all possible worlds".  The only improvement to this configuration would be to swap an FTDX-5000mp in place of the FT-1000mp - maybe one day, when people tire of all the knob twiddling on those transceivers.

One of the best (yet most basic) circuits of the last 50+ years is the OP-amp stereo mixer. 
With an adequate output amplifier, theoretically an infinite number of OP-amp mixers can be paralleled, mixing nearly any combination of audio inputs.

Have YOU ever used some sort of mixing board/box in you amateur station?

What were YOUR results?