How to reduce start-up pop on monitor controller

[canidoit]

Hi, I have an Audient Nero that when you completely shut it down, turn off the power source, the next time you power it up, a large full +18 pop will emit, sending a large pop noise to your active monitors which I leave at unity.

I was wondering if there is anything that can be done to catch those pops by adding something to the TRS outputs.

What is causing this, is it a voltage spike on start up?

 

[thomasdf]

Did you try putting a 1M resistor to ground somewhere, for the DC / static to discharge ?

It's always better to turn the monitor amp AFTER the controller, anyways

 

[zamproject]

Hi

The only cheap and 99% effective move I know to avoid this is the basic rules, power ON sender to receiver chain and power OFF receiver to sender chain...

I don't think you can -catch- this pops as easy in a passive way...but someone else may have an idea.

My desk have an active circuit for that at output with charge ramp and led/photocell combo that remote relays, shorting all trafos lines output.
At power on the relay open after few sec, and at power off outputs are shorted -instantly-, at least way before the supply discharge/pop. It's a safety feature to avoid broadcasting pop to hundred thousand FM/AM receiver in case of supply lost (the desk was on broadcast spec)

 

[JohnRoberts]

Back at my old day job we invested much design effort into benign turn-on/off characteristics. Even though we were designing value (cheap) SKUs the customers interpreted loud turn-on/off transients as shoddy design.

The premium solution is a delayed turn-on relay that gives the SKU time to settle before connecting the audio. Cheaper designs use JFET shunt turn-on mutes.

A less elegant solution could be a manual audio disconnect switch so you could wait for the SKU to settle before connecting it to the powered monitors. Is there some reason you don't just power up the monitors last?

JR

 

[canidoit]

Hi All,

I have a centralised power switches, then it branches out to these smaller powerboards. Sometimes I am tired when I turn off my powerboards of the monitor and monitor controller, and the following day when I turn on my power switches, I realise I forgot to turn off the powerboard of the monitor. So bam, instant pop, very loud.

@thomasdf do you mean make a TRS connector and put a 1m resistor connecting Tip and Sleeve? Would that change the sound quality?

Is there a solution that I can make and put in between TRS connection from Monitor controller to Speakers?

Thank you All!

 

[pucho812]

You could buy a power sequencer. Furman and others make them. It basically turns on each outlet of the box in a sequence so you could try that.

 

[thomasdf]

My 1M resistor idea (from hot to ground, as in some guitar pedal designs) was in case your unit has a weakness and gets DC in the signal path for whatever reason.

If it’s just a matter of turning on and off your pieces of equipment in a correct order, everything has been said already
You could have switches lined up and start from left to right then turn off right to left, or having timed switches, timer relays, etc etc

 

[canidoit]

The powerboards are in different spots, but I like the idea of a Power sequencer. Il do some research to see if they have a one outlet delay power board so that when I turn the main switch on, atleast that power board for the speakers will be delayed to allow the monitor controller to pop first.

 

[Rob Flinn]

Can you not turn the monitors on after the monitor controller ? I always turn the speakers on last & off first for this very reason.

 

[totoxraymond]

You could have switches lined up and start from left to right then turn off right to left, or having timed switches, timer relays, etc etc

That's exactly how i did it in my home studio, i bought a cheap Rack-mounted multi switch device intended for lighting (very crude lighting control imo but good enough for my usecase). This also allows me to turn on power for my different racks only when i need them.

 

[ccaudle]

Does slow start of the pre-amp power supply rails eliminate or at least reduce the pop? That seems like it might be easier to achieve than adding a relay to the output of every channel.

 

[JohnRoberts]

Does slow start of the pre-amp power supply rails eliminate or at least reduce the pop? That seems like it might be easier to achieve than adding a relay to the output of every channel.

That depends upon the design but cannot be counted upon. I recall an issue with early class D power amps where low rail voltages could lead to indeterminate output states, sometimes allowing the amps to be pulling up and down at the same time,,, no bueno.

Typical analog designs can lose negative feedback at too low rail voltages. The only sure to work strategy is delaying the output until after the circuits have stabilized, and provide instant turn off, to avoid nasties as the power supplies discharge.

Old school analog power amps (like the CS800) were designed to operate well below nominal mains voltages, making them popular in some foreign countries with less than robust mains voltage. As I recall the early digital amps were designed to completely shut down when sensing low mains voltage so they would not release magic smoke.

JR

 

[sodderboy]

My day-zero tech training started with "no drinks in the control room", then "here is the proper power-up and power-down sequence for the room, never do it differently". SSL sez a Duality can be power-cycled with speakers ON, but neither SSL nor I will sign an insured guarantee that you will not lose a horn diaphragm or worse some day. You just have to practice proper power sequencing.
That said, there are good solutions to sequencing. The Furman M8S sequencer is what I use for artist studios, no sequence lists necessary. One switch ON and OFF for three circuits. The MS8 can be scaled to high current situations with remote power strips but that is beyond the smaller project studio. The next-best, the switches previously mentioned, I use a 1U switch bank, sold as a DJ product. My only complaint is that the neon lights go dark quickly in any of the models. And you have to watch your over-all power on the switches/box.
If electrical code inspection is not an issue, DIY kinda people might think about quality extension cords, 25 foot and properly sized for current requirements, broken by a 1U rack box somewhere, with three sideways 15A wall switches mounted on it. Outlets and power strips can be wherever you want. Just remember, for equipment proximity reasons, that all the studio power goes through that one area.
A studio has to be properly power sequenced, we determine how convenient it is to do that.
Mike