AMB Laboratories DIY Audio

[Peppe]

If you put the transformer in a second box or wallwart what is the best way to control on/off? In the gallery i saw two builds with power in a wall-wart, but no on/off switches.

Since the Jameco empty wallwart enclosures are no longer listed on their site I was just going to put the power supply in a radio shack project box. Fused IEC entry on one side, transformer in the center, and 4 pin mini din female on output side. I would then use male to male 4 pin mini din cable to connect to the main unit. Without a power switch the unit would then be on 24/7.

To control on/off I was thinking the best thing to do would be to put a Dual Pole single through switch (DPST) on the back of the main unit. This will allow the amp to stop the circuit for each power rail simultaneously. Will that cause any issues for the transformer as its primary loops will always be on?

If a switch is a good idea, Does it matter which transformer leads go to the switch (+15v or 0v), is there a best practice?

Final question, looking at the gallery it doesn't seem to matter which wire in each secondary pair goes to each pin in the 15VDC input headers, is that true as well?

Thanks all

[amb]

The CK²III doesn't draw very much power, so it's ok to leave it on 24/7 and won't cost much in electricity. If you must put a switch on there, I recommend doing it on the transformer box.

[Peppe]

Sounds good. Keeps it simple.

[DorkVader]

The CK²III doesn't draw very much power, so it's ok to leave it on 24/7 and won't cost much in electricity. If you must put a switch on there, I recommend doing it on the transformer box.

I'll probably be keeping mine on 24/7, so this is good to know beforehand (plus I don't get billed for utilities).

[particleman14]

electronics don't need sleep! unless they're running too hot! my ck has been on last 5 days, just come home and throw on the phones lol

[DorkVader]

Yep, I leave all three of my computers running 24/7, which is totally necessary. (I'm using a laptop solely as a spare monitor, + 1 real computer +1 backup-and-file-server) What electricity?

If we're going to be putting our transformer in the same box as our amplifier, are there any precautions to take to minimize hum? I've heard about rotating it and whatever, but is there a financially-sane option to shield it somehow? Perhaps I'll move the transformer to another enclosure someday, but I'll probably use a 5-pin DIN connector, because they're fantastically inexpensive.

[amb]

If we're going to be putting our transformer in the same box as our amplifier, are there any precautions to take to minimize hum?

Distance is your friend, so use a larger enclosure and put the transformer as far from the amp board (and input wiring, including the volume pot) as possible. Also, use moderation when sizing the transformer. The larger it is, the stronger the magnetic field. If you're willing to have a shielded toroid custom made (I recommend SumR), that would help a lot.
Their prices are very reasonable for a custom made unit.

Trying to shield a transformer "after the fact" is usually frustratingly ineffective.

[MisterX]

Since the Jameco empty wallwart enclosures are no longer listed on their site I was just going to put the power supply in a radio shack project box.

You can find similar enclosures here---->
http://www.polycase.com/shop-by/applica ... ug-in.html

[cfcubed]

Just a couple notes about this build (posted about this @ HFO).
I'm convinced that 2-box builds are the way to go for most all amps, unless perhaps going w/fancy SumR tranfos and/or having at least 6" bet it & amp board. And playing w/rotation. I bought this transformer http://www.mouser.com/ProductDetail/Hammond/229B30/?qs=zAx27f%252bWkoGS%252bWSZlrK6qg%3d%3d knowing I was likely doing a 2-box build.

The "powerpack" is a $4 RS box w/fuse, A/C push switch & sits on floor so you can just turn on/off w/your foot. Whole bit is working flawlessly.
More thanks to amb, Alex & others for making the amp design available, making it an easy build, supporting it, etc.

[Iniamyen]

What is the silver enclosure you are using in that picture? I like it...