I designed analog mixing console for a living for many years (about 35, with some interruptions).
I hope that this long post will not annoy the readers...
My curiosity pushed me to open every console I could put my hands on, and truly appreciated Yamaha's models for their technical (and sound) quality and reliability and mechanical robustness: this is VERY important: in live tours it was not unusual to repair broken pots when a stage hand walked on the console, or to have a upper panel bent, and all the channel's pots broken, for some mysterious accident (the console fell off the stage).
I remember well an old Midas desk, a model LS4, 32 into 8 into 2, live sound console: a friend bought one in 1980, at the cheap sum of 17,559 pounds ex works (about 60.000 to 100.000 pounds to-day), then the price of a small house..
It sounded extremely well, better than my designs, and was built like a tank (you needed two or four very strong men to move it).
When left in the summer sun, the frame heated and expanded, and channel 1 (the leftmost module) worked intermittently because it disconnected from the bus PCB. We had to adjust some clearances.
What I can criticise of this Yamaha model (and many other model of the same Company) is the extremely complicated wiring of this console: too many cables, too many connectors, too many wiring looms...
Open a Soundcraft or an Amek of the same age: most of the wiring is done with a flat cable or a bus board connecting all the modules.
I read previous posters asking why there are still analog mixers on the market: the reason is the ease of use in respect to the digital ones: a competent mixing engineer can use any analog mixer after a very short time, whilst any digital mixer is quite different from the others, and there is a step learning curve. If you have a desk in a location that will be used by different mixing engineers, analog is better.
About the single sided vs double side PCB, and the SMD vs through-hole components discussion, you must consider that the channel's PCB main dimension is dictated by the number of controls (pots and switches) and the distance between them, for ease of operation. Most of the times this allows for a single sided board.
The number of boards that will be manufactured is usually very high, especially for input channel's boards (there are from 8 to 48 of them in a desk), so automatic placement of through-hole parts is economically reasonable (surface mounting is most of the times impractical because a single sided board needs space for traces under the components). Automatic placements allows for a lot of wire jumpers (or Zero Ohm resistors) to be used at almost no cost.
In fact, only the modules that are lower in number (eg master, groups, effects) were double sided.
For consoles that were intended for large numbers, we (and some competitor) used another solution : the channel's PCB was single-sided, and it carried all controls and connectors and some large component, whilst about all of the module's circuitry was on a custom hybrid circuit.
This resulted in a simplified production process (hybrids were tested and adjusted by the supplier, with automatic equipment) and an easier maintenance (if no pot is broken, replace the hybrid).
Now a double sided board of decent quality has about the same cost than a single sided one, so a channel is built with SMD standard parts on a double sided board.
Best regards
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