i'm wondering what the possible causes of hiss are in an audio mixer. i have an older mixer that has an unacceptable amount of hiss. i set all channel faders and gain to zero, but the hiss is still there on all outputs - headphone, main outs, aux outs. the hiss does increase when output levels are increased. can a power supply cause hiss?
Normally hiss comes from the front end., if it hisses with faders and gain at zero, then it's got to be later on in the circuit. A circuit, or even a block diagram, would be useful - so you can work out where it may be coming from. Is it on both channels?, if so you're looking for somethijng common to both.
It may be worth scoping the HT rails, see if there's noise on them.
It may be worth scoping the HT rails, see if there's noise on them.
The tone controls (assuming is has some) would be a good place to start.
If it's everywhere, could it be the 0V line has got polluted?
If it's everywhere, could it be the 0V line has got polluted?
Hiss is broadband white noise and will be caused by the circuit design itself.
It won't be the PSU 🙂
If it's an old design it may use transistors in a very basic arrangement for the active stages... or it may use opamps. Would have to see circuit.
But noise (hiss) is caused by the active devices and the cummulative effect of amplifying the noise from all the gain stages.
It won't be the PSU 🙂
If it's an old design it may use transistors in a very basic arrangement for the active stages... or it may use opamps. Would have to see circuit.
But noise (hiss) is caused by the active devices and the cummulative effect of amplifying the noise from all the gain stages.
If it's very old, some of the components may be deteriorating.
Especially resistors, capacitors and potentiometers as well as switches and connections.
Especially resistors, capacitors and potentiometers as well as switches and connections.
What brand is the mixer? Certain brands are notorious for producing junk designs (Behringer, American DJ).
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