Adding a vintage mixer to your stereo setup may seem like a great idea, but there is more then meets the eye!
Older is not always better:
VU meters, big sliders, lots of inputs. Mixers and input switchers are most of the time a centerpiece, so you would want one that looks good. Vintage mixers usually tick all the boxes, but with age comes one big issue:
Capacitors! They all eventuelly dry out, and in the audio business this means added distortion and noise. Byebye clean signal for sure. All devices differ in how much a capacitor plague affects them, as every capacitor ages differently. Glue that goes bad, drying out and sometimes even exploding.
In our case, it means the audio signal you wish to listen to might get affected heavily. In this case, I noticed this after hooking up a mixer from the 1980’s. Bought cause of the reasons above, VU meters big sliders and a nice showpiece. Only to later figure out that the old circuitry in this mixer cuts off a big portion of high frequencies.
Removing it from the chain resulted in better instrument separation and clarity, and overall ‘quality’ of said signal.
So, if you need a showpiece for your setup like a VU meter I would recommend getting a modern switchbox, but splitting the signal in two. One for your amplifier, one for your showpiece. Like an external VU meter box, in this case on its own seperate input so that it doesnt affect the signal.
Of course, this is not always possible or desired, so see if the unit you’re interested in is working as intended. Frequency tests on a VU meter can often show you if any frequency range is affected in your chain of devices. In this case, look at the volume ranges on things like 1Khz, 10Khz of even 20Khz. Compare to see if there are any volume differences.
Or, get the device in question out of the chain, and see if bypassing it makes any imminent changes to the audio quality. A passive switchbox would in this scenarion be helpful. The faster you can switch signals, the better your ears can pick up the difference.
So, a vintage mixer can hurt your audio quality depending on the unit itself. Try to bypass the unit or listen to your setup with and without it to see what difference it could/will make. This will help you learn what unit does what to the signal in your setup. Learn what makes your systel sound the best it can, not by any part changing the sound.