Head amp clicking noise

[Drew1234]

Hello gear heads I have a simple question I have been in the sound department for about 2 years and I'm trying to learn as much as I can I am lucky enough to run nice digital equipment with a company I work with anyway why does a board make a clicking sound as you increase your HA gain and u go past -13 and -37 I work on all kinds of digital stuff and they all do it

 

[museav]

Hello gear heads I have a simple question I have been in the sound department for about 2 years and I'm trying to learn as much as I can I am lucky enough to run nice digital equipment with a company I work with anyway why does a board make a clicking sound as you increase your HA gain and u go past -13 and -37 I work on all kinds of digital stuff and they all do it

When what goes past -13 and -37 on what? I can't offhand think of anything related to any of these that would cause clicking, much less at the same point on different devices, but are you referencing the markings on the gain control, the amount of gain being applied, the level at some point in the signal path (and in what units) or what?

 

[MNicolai]

I wouldn't call it a "clicking" noise, but I hear it all the time on our LS9. It's supposed to do that -- something to do with the internal gain mechanism switching between different amplifier circuits I believe as you go through different gain ranges.

 

[Drew1234]

When what goes past -13 and -37 on what? I can't offhand think of anything related to any of these that would cause clicking, much less at the same point on different devices, but are you referencing the markings on the gain control, the amount of gain being applied, the level at some point in the signal path (and in what units) or what?

Ok so I am talking about the markings in the gain structure the console I notice it a lot on is a ls9-32 and the other equipment that does it is called a Yamaha AD8HR and I don't know the units but if add more gain and you go past thoes numbers something inside makes a click you don't hear through the speakers or anything just in the equipment

 

[Drew1234]

Ok well thanks that's te same console I'm on

 

[FMEng]

Are you doing this test with no mic connected? Preamps (I know Yamaha likes the term "head amp," but the rest of the planet uses preamp) are designed to be terminated. Any preamp will seem noisy with nothing connected to it. On the test bench, we put a 150 ohm metal film resistor in place of the mic to measure the noise floor. As long as the console sounds fine in real use, don't worry about it.

 

[museav]

Ok so I am talking about the markings in the gain structure the console I notice it a lot on is a ls9-32 and the other equipment that does it is called a Yamaha AD8HR and I don't know the units but if add more gain and you go past thoes numbers something inside makes a click you don't hear through the speakers or anything just in the equipment

From the LS9 manual:

• The PAD will be internally switched on or off when the HA
gain is adjusted between -14 dB and -13 dB. Keep in mind
that noise may be generated if there is a difference between
the Hot and Cold output impedance of the external device
connected to the INPUT connector when using phantom
power.

And from the AD8HR manual:

• While adjusting the gain, you may notice that the sound
is briefly interrupted. This is not a malfunction. The
internal setting is switched in steps of 6 dB, and the
sound is momentarily muted so that the noise will not be
created during the switching operation.

• The PAD will be switched on or off internally when the
gain is adjusted between -14 dB and -13 dB. Keep in
mind that noise may be generated if there is a
difference between the Hot and Cold output impedance
of the external device connected to the INPUT
connector when using phantom power.

 

[fx120]

What you're hearing is known as 'zipper noise' and is a result of the preamplifier's gain stage introducing and removing individual resistive elements from the signal path as you request more or less gain out of the circuit. Because the changes are steps in gain instead of a linear gradient, it results in slightly audible clicking as the relays switch in and out. This is how the traditional logarithmic taper potentiometers that exist on most analog consoles and some digital consoles (PM5D) are replaced to allow control of the analog gain from a remote location, in a precise and repeatable manor.

Logarithmic resistor ladder - Wikipedia, the free encyclopedia

There are various methods for eliminating zipper noise, but for the most part the additional cost of implementing it on each preamplifier in a digital console would not be worth the result.

 

[TimmyP1955]

All normal. The zipper noise is the result of the method of changing gain. The internal click I believe to be a relay.