Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Power supply upgrade

Hi Nick, I appreciate your work and am potentially interested in one for my G68AXV.

Does the fan kick in with the PS fitted? My G68 is close to my listening poition and any excess fan noise would be undesirable.

Hi Cliff,

The SMPS is particularly cool and quiet running, and its inevitable that a linear supply will make that worse. The supply itself is physically noisier, some of them unacceptably so, though the large Condor and Power-One supplies are very quiet.

They still disipate more heat than the SMPS though, so this is only going to make it more likely that the fan would come on. Whether that actually happens will depend on the ambient temperature and the degree of local ventilation. I wouldn't assume that the fan won't come on, and I wouldn't set the fan control to "Always Off". I'd leave it to the default "As Required".

I'm trying to minimise all these downsides by various means though. Choosing a large, over-rated supply will mean that the transformer is lightly loaded, and runs more quietly (and with less ripple!) Large supplies have larger heat-sinks, and will run cooler.

Using the CP498 means that the "hot end" sits above the fan and the air inlet, giving convection cooling the best chance. The CP498 also enables me to easily de-couple the transformer from the heat-sink. Part of the noise comes from the vibration from the transformer coupling directly to the heat-sink & chassis. Mounting the xformer in rubber bushes (but still with an earth strap) reduces noise very effectively.

This also enables the heat sink to be regidly mounted to the controller chassis, allowing the chassis to contribute to the heat-sinking. The LPS heat sink on my 861 is rubber-mounted to the chassis, which in hindsight is the worst case. The ideal configuration is a compliant-mounted xformer and a hard-mounted heat-sink, which is what I'm proposing here.

The short of it is that there are several things that can be done to manage heat and noise, but I'd assume that the fan will come on from time-to-time.

BR, Nick

Please put me down as being interested in one (G68ADV).

Cheers, Ian

Many thanks for the detailed answer. I'm being indecisive at present so best leave me off the list for now
Cliff

Can anyone clarify if the wire to board connector on the SMPS is common across the various units used in G61, G68 and 861 i.e. Molex SPOX 3.96mm pitch ?

Avi

Hi Nick

Thanks - yes, please count me in. I hope you're enjoying your DSP6000s

Steve

I'm interested for a G68ADV.

I think I'd better get some more PSU's.

Nick

Great work Nick!

I would definitely be interested in a drop in CP498 for my G68ADV.

David

HI Nick,
I think this could be a better choice perhaps?
the +/-12v supplies are balanced in terms of current.

Link

The HCAA-60 would be fine, but if there was a benefit to balancing the 12V supplies, then the bigger HCBB-75, CP-131 or HDBB-105 would be better still. The CP-498 is the only triple output supply where the 12V supplies are different, but the processor's load isn't balanced either. All processors, whether 8-series or G-series, pull more current from +12V than -12V. My aim was to have each line running at the smallest possible fraction of capacity, as that's likely to give the best ripple. The greater the capacity, the larger the storage capacitor, and the less it discharges in between each charging cycle. That logic does point towards the CP-131 being a good candidate, and I'll look at getting hold of some of them. I summarised the specs of the main candidate supplies in this table, originally posted on 08-10-11, and I ought to update it with some new power consumption measurements:



Nick

Hello Nick

Very interesting and well researched topic.

Would it be possible to use your linear supply in a G91DH?

Inside it looks like this:


Clearly the presence of the drive makes things a lot tighter.

Thanks again for your efforts