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  #501  
Old 10-16-2020, 04:22 PM
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The power supply was a rabbit hole in a rabbit hole... long story short is that it's all switch-mode.

There are actually 4 switch-mode devices in that chassis. The big one on the bottom is a Meanwell switch-mode 24 volt/300 watt PS, and the chip amp (itself a switching device) doesn't care. The DAC chip needs two different feeds: +/- 5V for the digital part and +/- 12V for the analog, then the op-amps need at least +/- 12V as well. So top right is a little board I wired up with two DC-DC converters to make +/- 5V and 12V out of the single 24V supply.

The boffins at diyaudio are pretty clear that the DAC chip itself doesn't really benefit from linear power, but the op-amps might, so the board is designed with some jumpers to allow separate supplies for the two feeds to the DAC and a unique feed for the op-amps. So you can pretty easily feed them from a linear PS, but I didn't. Maybe later if I run out of other projects...
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  #502  
Old 10-16-2020, 10:42 PM
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Ed,
I might be interested in a board and AD1862. How much $$ do you have in this in parts (approx)? I only did 1 semester of EE and that was in 1973, so wiring up a little board with two DC-DC converts might also require a little direction...

Peter
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  #503  
Old 10-16-2020, 10:48 PM
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Kind of off for this thread, but we're going to be redoing the system in our Den soon, and the current system (old but high quality for what it is - Pioneer Elite but NO HDMI) won't do for a new TV. The Pioneer is 17" deep and with all the wires out the back, more like 19. Does anybody know of a relatively high-quality AV Receiver that is COMPACT? It would seem like quality Class 4 amps could be considerably smaller than the older equipment and still quality sound.
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1992 Miata ("SSM") race car
2016 Toyota Highlander (wife's DD and my new tow vehicle
2017 VW GTI SE (DD)

Gone and missed:
2009 911 C2S Coupe "The Green Car"
2004 Toyota Prius - sold to son's girlfriend
2006 Dodge Durango - sold to a Dorki
2003 Acura MDX - Just shy of 200K
86 Black 911 Coupe race car (owned 2010-2016)
86 Gold 911 Targa (owned 1998-2012)
82 WineRedMetallic 911 Targa (owned 1986-7)
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  #504  
Old 10-18-2020, 09:24 AM
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To the DAC question, you don't have to use my weirdo solution for power since you probably aren't trying to stuff everything in one box that already has a 24VDC power supply. The DAC doesn't take a lot of power, a wall wart for +/- 5 and one for +/- 12 should be good.

The board alone was $15 from the US supplier but can be as low as $5 from a Chinese supplier. Miscellaneous electronics parts $40-50, DAC chips (one for each channel) 2 @ $15ea from China or $28ea NOS US, and output op-amps can be anything from 2 5534 @ $1ea to 2 627 @ $28ea.

So a top of the line board runs about $185 in parts. Add $15 or so for a board to convert from optical/coax or USB, $50 for power supplies, and a $50 case and it's not hard to have $300 in the whole thing.
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  #505  
Old 10-18-2020, 07:07 PM
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Sounds good - if you can get others interested, count me in.
Peter
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Peter (not "Pete") K.
IndexFingerRacing.com

1992 Miata ("SSM") race car
2016 Toyota Highlander (wife's DD and my new tow vehicle
2017 VW GTI SE (DD)

Gone and missed:
2009 911 C2S Coupe "The Green Car"
2004 Toyota Prius - sold to son's girlfriend
2006 Dodge Durango - sold to a Dorki
2003 Acura MDX - Just shy of 200K
86 Black 911 Coupe race car (owned 2010-2016)
86 Gold 911 Targa (owned 1998-2012)
82 WineRedMetallic 911 Targa (owned 1986-7)
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