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So I want to build a DAC

sigmatechnica

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Jan 19, 2020
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Hi all,
So I want to build DAC. What would be a good chip to base it on?
  • i2s interface (it will be USB via one of these: http://jlsounds.com/i2soverusb.html)
  • Primarily for 16/44.1 formatted media. i don't see much point in going higher (unless anyone can convince me i should)
  • No microcontrollers, FPGAs, DSPs or things that need programming
I had initially thought a tda1541A or pcm56 (i have both) and that may still be an option since they are easy(ish) to implement, but after considerable reading am starting to go off that idea... things have moved on, is there anything with the same or better performance that isn't too much of a hassle?

Thanks
 

Count Arthur

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I built a non oversampling DAC based on a TDA1545A and a USB interface many years ago. It sounded OK and I enjoyed building it, but sonically it was easily bettered by the CD player I had at the time and later a fairly innexpensive HRT Music Streamer II+ USB DAC.

Given the superb performance of some of the reasonably low cost DACs that have been reviewed here, I wonder whether building a DIY DAC makes makes much sense in terms of price and performance. By the time you've factored in the cost of components and a case, etc. you can easily spend more on a DIY project, often based on older DAC chips, than a retail DAC.
 

ElNino

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That JLSounds board is easy to interface with pretty much anything, since it's configurable to output the formats commonly used for old R2R DACs as well as I2S. I'm not sure if you've seen it, but JLSounds also makes a piggyback module that uses AK4493, which would be a good starting point for a really simple plug and play sigma-delta DAC.

If you're looking to build an old-school R2R DAC with oversampling in software, this probably isn't the best forum for advice on what old part "sounds best". They're all pretty easy to implement with the board you're looking at. I'd probably pick a part that has voltage out like AD1865 as a first project. Another thing to consider since you're fine with 44.1/16 is to pick up an old higher end CD player from the PCM63 era (most of these are cheap now), tear out the transport, and integrate the JLSounds board as a digital input. There's a website called HifiEngine that has service manuals for most of the old CD players that were any good. If you know what you're doing it's not difficult.
 
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sigmatechnica

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Ok some background here might be beneficial. This isn't just a DAC project, it's an all-in-one streamer box with PC, 4 channel amplifier and active crossover all crammed in. It's very compact (and extremely heavy!) tiny UK houses at astronomical prices force extreme measures. i'll post some pics if anyone wants some eye-candy

So this dac board has to be crammed into the space available. I had considered the diyinhk boards but they were all a bit the wrong shape and fitted together in annoying ways that didn't work, so now the plan is to use the nice flexible (and small!) JLSounds board and build an accompanying dac around it.

Old r2r DACs come in nice easy packages i can bung on some matrix board with appropriate analog support stuff. you can achieve surprisingly high density with some tricks and carefull layout. I'm interested in 'measures best' if it doesn't sound good after that then either its something else in the chain or it's crap music! that said there's posibly not much point going for something better than -96db noise/distortion since that is the limit of 16 bit anyway. by modern standards, looking at the excellent testing of many DACs done by Amirm, that's a fairly tame requirement. maybe not so tame with vintage chips though.

Software oversampling saves a chip! looks like a winner to me, though software on the whole has been a pain in this project (original plan was for the active crossover to be done digitaly on the integrated PC, but the complexity made for a very fragile configuration that broke down at every opportunity)
 
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