Two mixers, one pair of speakers, but not like you think

mistercharlie

There are plenty of threads on Reddit and elsewhere about running two sound sources into the same pair of monitors, simultaneously.

That’s NOT what I want to do.

I want to know if it’s safe to connect two mixers to a pair of Yamaha HS8s, but only ever use one at a time. It’s a simple wiring convenience, and the HS8s have a TRS and an XLR on the back.

My use-case is that I have an audio interface and a mixer. Sometimes, when just listening to music on my Mac, using the mixer seems like a waste of power. I thought I might hook the USB audio interface directly to the spare speaker inputs.

Are the speaker inputs connected in a way that might degrade audio quality with both of them hooked up?

gonekrazy3000

I've noticed severe sound degradation when I connected 2 sound sources to my hs8s even though just 1 was actually powered on. Ended up only keeping the xlrs connected. Mind you the secondary source that was connected was a tv's stereo out to the TRS and not a second mixer. So your mileage might vary.

Samu

That’s the way I do it with my iLoud Micro’s…

iPad 3.5mm hooked to the 3,5mm input, UR242 hooked to the computer and RCA inputs on the iLouds and on top of that BT from iPhone to the same speakers,

Sure if I run all the stuff at max input at the same time the time overload light starts blinking 😎

rs2000

@gonekrazy3000 said:
I've noticed severe sound degradation when I connected 2 sound sources to my hs8s even though just 1 was actually powered on. Ended up only keeping the xlrs connected. Mind you the secondary source that was connected was a tv's stereo out to the TRS and not a second mixer. So your mileage might vary.

Yes. Unfortunately, the two inputs on the HS8 are unbuffered and simply wired in parallel so if cou connect two audio sources simultaneously, you'll be faced with two problems:

• Audio levels will be reduced because the two outputs "have to fight against each other" due to the much lower input resistance of the other output compared to a conventional audio input port
• If the outputs are DC decoupled by capacitors, the much reduced target impedance will make it a high pass filter with a much higher frequency than it was designed for, giving you a reduced level in the bass range.

A dirty but most likely acceptable hack would be to add serial resistors (I'd suggest starting with 10..22k) in each audio output line in order to passively mix the outputs and increase the input impedance for both audio signals.

mistercharlie

It looks like I'll have to spring for a Mackie Big Knob, or similar. Or just use the mixer. The extra power it uses probably has a smaller impact than manufacturing and shipping yet another gadget to my door.

rs2000

If you have a soldering iron or know someone who does, inserting resistors is worth a try.
It's no different from a passive mixer.

mistercharlie

@rs2000 said:
If you have a soldering iron or know someone who does, inserting resistors is worth a try.
It's no different from a passive mixer.

No problems there!

rs2000

Cool! Good luck then. Make sure you add a resistor to each signal line except ground (1 if unbalanced, 2 resistors if balanced).

OnfraySin

I use a little mixer, Q502, for this task.