DAC-building resources

[shleepy]

My (much-more-electronics-building-knowledgeable) friend and I might want to do a long-term project for building a DAC/amp. The eventual outcome would be a high-quality headphone DAC/amp, perhaps something similar to Fubar III: USB-input (USB2 preferred), maybe also s/pdif, RCA-outs (a pair or two), and a headphone jack.

If we wanted to start the project virtually from scratch, where should we look for parts, and what are some good resources (i.e., informational websites) for research into this? Ideally, it would be with OEM stuff that's as functionally specific as possible, if you know what I mean.

Thanks!

[error401]

Do you have a budget in mind? This is the kind of project that can easily span the gamut as far as quality is concerned.

Do you know anything about the type of amplifier you want to use? Solid state? Valve? Opamps or discrete - or hybrid? Feedback or not?

I think if I was going to do this with as little design effort as possible, I'd go with:

Opus DAC with S/PDIF and USB input modules and their I2S switch and power supply. Optionally add their ASRC, bal->SE stage, or swap for the Buffalo or PCM1794 based DACs. They're all prebuilt and easy to use. See Twisted Pear Audio News

Add a CKKIII (I really like mine), M3, PIMETA, SOHA, Millet to taste. All these designs are well documented and have professional boards available (I think). You can find info on the CKKIII and M3 from AMB Laboratories DIY Audio Site and the PIMETA at Tangentsoft . I don't have anything on hand for SOHA or Millet information, but you'll find it with the search. You can buy kits for the amb projects (I think, you might have to email him) from Jeff of Glass Jar Audio (jrossel on the forums).

Any of these setups should seriously outperform the Fubar III, but will be much larger and probably cost you 2-3 times as much. A simpler (and more similar) setup with an AlienDAC and Mini3 could probably be built in a similar sized enclosure and have similar (probably a bit better) performance to Fubar III for around the same money.

[shleepy]

I'd have to look at the links you gave, but for now:

Amp: solid state / opamps.
Budget (woops - forgot to mention this): up to around $300.
Size - doesn't matter

[error401]

At that price you won't be able to put an Opus build together, nevermind a built-in headphone amp, so scratch that idea .

I think you'll probably have to forego the S/PDIF idea then too, since that will significantly complicate the DAC design (you can't just use a single chip as DAC and USB receiver anymore), and I don't think there are any readymade inexpensive designs to do this. That means you're left with something PCM270x-based like the AlienDAC, which is a good DAC in its own right, and it's the same chip used in the Fubar. A kit from Glass Jar will run you about $50.

For the headphone amplifier, I think the PIMETA is a good choice for you. It's a three-channel (active ground) opamp-based design with IC buffers on the output, and there are lots of 'tweaks' you can do to the basic design later if you lust for more quality. One issue with this design is the buffers, which are difficult to source right now. You will need to find a replacement, either a discrete implementation, like a 'diamond buffer' board or a similar integrated chip like the LMH6321, but this may require minor modification. Per-Anders sells the QRV05 board that is supposed to work well, but the SMD might be a bit challenging for you, and it'll drive the price up), and I believe the JISBOS kit from Glass Jar would work well too. Depending on how you choose to do it, the PIMETA build can be as cheap as $100 to probably around $300.

You might also like the M3 from amb, which has an opamp input stage and discrete MOSFET outputs. It'll be more costly than the PIMETA, probably out of your budget, mostly due to the more elaborate power supply and larger case required. It doesn't have the issues with part availability that the PIMETA does, or the same tweakability, but it is an excellent (probably better, IMO) design and powerful enough to even drive some small speakers, and it's designed to be a desktop amp, while the PIMETA aims for portability. A basic build should run you around $150 for parts (plus shipping).

You'll need bipolar power supply like the σ22 from amb (Glass Jar has kits at ~$100 including transformer). If you can get ahold of Russ or Brian at Twisted Pear, they might sell you one of their LCBPS kits separately which should be significantly less expensive and would work well.

Don't forget to budget for the casework, which will be a significant part of the cost. You'll probably spend about $50 on the chassis, plus probably $15 on a volume control and $15-20 on connectors. Add hookup wire, a power switch, power inlet module, screws and standoffs and you're up some more. If you go the M3+AlienDAC route, you're probably looking at $300-400 all told for a budget minded build. The PIMETA is probably a bit less, but not that much, maybe $250-$350.

Just a couple ideas, there are lots of choices, at least in the amp section.

[JamesL]

Mini3, Pimeta, ckkIII, Dynalo, PPAv2, and the M3, I think covers most of the more popular solid state amps in your price range.

As for the dac, there are not as much choices in this area.
The Alien DAC seems like the most doable dac in your price range, as well as the stand-alone opus usb module. Scott-Nixon also distributes some dac kits as well.

[pistolpete111]

Depending on your soldering ability you may want to consider the "Jambo DAC". There is a thread about it here: Jambo DAC.

It would set you back about £90, and would be far superior to anything else in its price range (with similar inputs and outputs). It uses the same DAC chip as the Opus (either a 8740, or 8741), but it runs in dual mono (i.e. 1 DAC chip for each channel) has USB, 2x Optical, 1x Coax, 1x Optical out, and RCA out.

Kits (with professional PCBs) are available, but you would have to assemble it yourself, whereas the Opus comes preassembled.

[shleepy]

Thanks for the advice, folks! I'll be looking into this, and will post info about my DAC adventures when it becomes available.

[Mazuki]

There's also some DACs at Hifidiy.Net

The guy lives in Los Angeles, so no worries about shipping.