Mac Mini Power Supply Question

serengetiplains · « **on:** 15 Jul 2009, 11:17 pm »

Does anyone know how the trigger works on the Mac Mini power supply? I'm wanting to swap out the switcher for a linear supply to reduce noise in my computer audio setup, but I have no idea how the trigger works on the switcher. TIA!

konut · « **Reply #1 on:** 15 Jul 2009, 11:52 pm »

I don't know, but you might want to ask here.
http://www.123macmini.com/forums/viewforum.php?f=55

serengetiplains · « **Reply #2 on:** 16 Jul 2009, 12:30 am »

Thanks, k, I'll try over there also.

serengetiplains · « **Reply #3 on:** 16 Jul 2009, 05:48 pm »

No help as yet from the 123 forum. Anyone else here?

rydenfan · « **Reply #4 on:** 16 Jul 2009, 08:01 pm »

You are having noise issues with your mini in your setup? Mine is dead silent.

dvenardos · « **Reply #5 on:** 16 Jul 2009, 09:47 pm »

Have you tried using a power conditioner?

serengetiplains · « **Reply #6 on:** 17 Jul 2009, 12:44 am »

Hi guys, the noise I'm referring to is electrical noise generated into the mains and into the Mini other components by the switchmode power supply. The Mini is quiet enough physically.

I do have a conditioner, but I'm wanting to reduce noise further than a conditioner allows.

shokunin · « **Reply #7 on:** 19 Jul 2009, 12:04 am »

What do you mean by "trigger". The power supply on the mac mini is similar to a typical laptop, basically an 18.5v power supply. If you go mp3car.com forums there's lots of people running mini's in their cars using 18.5v DC supplies, except these supplies have delays to make sure the mini shuts down even if the iginition shuts off.

Robert57 · « **Reply #8 on:** 19 Jul 2009, 12:16 am »

Maybe I have been smugly operating with a false sense of security, but doesn't an APC or similar battery UPS back-up deliver clean, even power like a power-regenerating conditioner, eliminating the AC nasties and smoothing out power spikes and sags? Or does the power just flow direct and uncleaned from the wall outlet through the UPS under normal (compromised) conditions, and ONLY when the power goes down completely does the battery kick in? My new APC UPS battery unit cost only $ 90 or so, and I thought it would help protect the computer and monitor from AC glitches and grunge at all times, as power would be continuously cleaned and fed by battery power. Am I mistaken?

Rob

oneinthepipe · « **Reply #9 on:** 19 Jul 2009, 02:42 am »

What about using a Felix?

There are several Felix threads:

http://www.audiocircle.com/index.php?topic=51941.0

silverlight · « **Reply #10 on:** 24 Jul 2009, 12:06 am »

Just a head's up, Wayne at Bolder Cable is providing a custom solution for the Mac Mini (18.5v, iSense compatible), which should be a huge upgrade. Will post once I receive it and have it burned it with impressions.

jtwrace · « **Reply #11 on:** 24 Jul 2009, 12:33 am »

Quote from: silverlight on 24 Jul 2009, 12:06 am

Just a head's up, Wayne at Bolder Cable is providing a custom solution for the Mac Mini (18.5v, iSense compatible), which should be a huge upgrade. Will post once I receive it and have it burned it with impressions.

Look forward to your impressions...cost?

silverlight · « **Reply #12 on:** 24 Jul 2009, 12:38 am »

I don't know if it will move around a bit, would need to defer to Wayne, but I purchased the standard PSU and he's doing the changes to make it work with a Mini (taking it to 18.5v and the iSense resistor, etc.). He's also going to upgrade the case.
http://www.boldercables.com/servlet/Detail?no=395

I provided the following cable to Wayne:
http://store.mp3car.com/MacPac_Power_Cable_Kit_p/cbl-002.htm

Wayne1 · « **Reply #13 on:** 24 Jul 2009, 02:23 pm »

Thanks for your interest in this project.

If it goes well, this will be a normal offering.

The case will be 7" w x 3" h x 4.5" deep

It will have an oversized E-core transformer, HexFRED rectifiers, Nichicon filter and reservoir caps with Sonicap bypasses. It will produce a tightly regulated 4.5 amps at 18.5VDC. BallPark price will be $500-$550.00 including the interface cable. I'll try to post a picture of the case a bit later.

Wayne1 · « **Reply #14 on:** 24 Jul 2009, 02:57 pm »

Here is a picture of the case that will be used for the MacMini power supply.

I can provide a brushed aluminum cas that would be 12 x 3 x 12 for a hundred dollar upcharge. It would also ass another 4 weeks to the project timeline.

serengetiplains · « **Reply #15 on:** 24 Jul 2009, 04:39 pm »

Guys, no info on how that pesky iSense works? Is it a trigger that turns on the switcher supply? Or is the switcher supply always on? If the former, then any linear supply will work, though the physical power button will be bypassed (possibly also the software-based restart and shut down commands).

You can get an excellent Acopian linear supply with 0.25mV ripple for $280 new (4.5A). The 3A model ($230) would work just fine. The 2.1A model ($205) would probably likewise work as from what I've read the Mini draws about 2A max.

serengetiplains · « **Reply #16 on:** 24 Jul 2009, 05:07 pm »

Ok, I just determined that the supply is always on. My guess, therefore, is that the iSense facilitates turning on an electromagnetic switch in the Mini.

Connecting the iSense through a 3.4K (Intel) or 6.8K (PPC) resistor to ground seemingly works. Thus one need only chop the cable off the switcher supply, connect it to the new supply and connect the iSense to ground through an appopriate resistor.

roscoeiii · « **Reply #17 on:** 1 Jul 2010, 04:57 am »

dusting off an old thread...

I just got a Mac Mini without a power supply and so am wondering if anyone could suggest any possibilities for an improved power supply that will cost me less than $100. I could get the standard supply, but wondered if there were other possibilities that I should explore that could get me better performance for not too much more.

At this point the Bolder Mac Mini power supply is well out of my price range...

Bigfish · « **Reply #18 on:** 1 Jul 2010, 12:18 pm »

Since this thread was originally started has anyone actually evaluated the sound quality from a Mac Mini with a Linear Power Supply versus the Stock Switching Power Supply? I have talked and traded PMs with many folks about this issue. All responses have been that a Linear Supply should make a significant improvement but I have not actually talked with someone that has evaluated the upgrade in their system.

I look forward to reading your replies.

Ken

jtwrace · « **Reply #19 on:** 1 Jul 2010, 12:26 pm »

Quote from: Bigfish on 1 Jul 2010, 12:18 pm

Since this thread was originally started has anyone actually evaluated the sound quality from a Mac Mini with a Linear Power Supply versus the Stock Switching Power Supply? I have talked and traded PMs with many folks about this issue. All responses have been that a Linear Supply should make a significant improvement but I have not actually talked with someone that has evaluated the upgrade in their system.

I look forward to reading your replies.

Ken

I'm still staying open minded as I haven't hear it but I will say that I don't hear any difference when I plug my Mini into the wall or into a PLC. I'm still trying to wrap my head around how the computer really is going to to be affected enough to make a difference sonically.

If anyone cares to explain whey they think so, I'm all ears.