Hypex Ncore mute on startup - custom input board

[morethinkingcapacityneede]

Hi there. I am making a DIY build with some Hypex Ncore NC500MP boards. There will be a couple of amp modules in a box with custom input PCB for signal detect auto power on, 12V trigger IO, and temperature monitoring.

I was thinking of adding some kind of soft start functionality, i.e. have the amp modules muted on turn on/off, to reduce pops and/or speaker damage. At the moment, this is done by using the amp power good signal to control the amp mute input. Is there any point in doing this if I am controlling the amp ps enable line to bring amp modules in and out of standby mode. For reference, the amp module datasheet is here: https://www.hypex.nl/media/90/08/74/1646057938/NC500MP_04xx.pdf.

If anyone has any comments, suggestions, advice, that'd be much appreciated.

 

[Rick Sykora]

Neurochrome.com already has a good soft start. If it does not work for you, he also offers some useful advice here:

The Ultimate Guide to Soft Start Design

The toroidal power transformers in audio amplifiers draw large currents on start-up, which reduces their lifespan. This guide presents how to design and make a soft start using inrush limiters. I explore the limitations of power resistors, NTCs, TRIACs, and MOSFETs when used in a soft-start for...

neurochrome.com

p.s. Also Audiophonics has a range of options that are so inexpensive, may not make sense to design your own…

Softstart & Protection | HiFi Sono DIY | Audiophonics - Audiophonics

softstart and protection

www.audiophonics.fr

 

[boXem]

Hi there. I am making a DIY build with some Hypex Ncore NC500MP boards. There will be a couple of amp modules in a box with custom input PCB for signal detect auto power on, 12V trigger IO, and temperature monitoring.

I was thinking of adding some kind of soft start functionality, i.e. have the amp modules muted on turn on/off, to reduce pops and/or speaker damage. At the moment, this is done by using the amp power good signal to control the amp mute input. Is there any point in doing this if I am controlling the amp ps enable line to bring amp modules in and out of standby mode. For reference, the amp module datasheet is here: https://www.hypex.nl/media/90/08/74/1646057938/NC500MP_04xx.pdf.

If anyone has any comments, suggestions, advice, that'd be much appreciated.

Having tried this solution, my advise: don't loose your time. The amp is muted until ready and then automatically un-muted. Keeping it muted and un-muting it later has no effect on startup noise. Exploring various ways of grounding can bring more satisfying results.

 

[Count Arthur]

Hypex make a soft-start module: https://www.diyclassd.com/products/diy-components/smps/softstart-module

However, as others have mentioned I don't think this is necessary with their current SMPS powered amp modules. Early on, when they first released their UcD modules they originally used them with a linear power supply, with toroidal transformers and a large bank of capacitors. For larger transformers, a soft-start was recommended to prevent the transformer and capacitor bank inrush current from blowing fuses or tripping RCDs.

Inrush current - Wikipedia

en.wikipedia.org

Hypex UcD700HG with linear PSU and soft-start:

 

[Rick Sykora]

I will add that I missed earlier that you plan to use Hypex MP modules, so the need for a soft start may be lessened. Otoh, the in-rush current on these is not insignificant and might be still worthwhile...

I would suggest dropping a quick note to Hypex support and see what they recommend.

 

[morethinkingcapacityneede]

Hi All. Thank you for all your replies. I think my question has been answered.

I won’t bother putting in extra muting driven by the amp power good signal. Similarly, I’ll let the amp SMPS power up without additional soft start circuitry.