[myinitialsaredac]

Hello, I was just taking a look around and found the devilsound DAC and was wondering if anyone had any input on it.

devilsound labs - DAC - digital audio cable

Interesting design to say the least.

Dave

 

[jrosenth]

I love the NON-OS sound and have been considering one of these myself.

It is an interesting circuit.

 

[myinitialsaredac]

Indeed it is an interesting circuit,
any input ? =)

Dave

 

[Lil' Knight]

Look like the Bantam DAC:

$250? Looking at the picture, a RCA plugs cost 70$ already.

 

[myinitialsaredac]

Wow those are expensive plugs oO.
Very similar looking to the bantam dac....

Any first handers with the devilsound DAC?

Dave

 

[Lil' Knight]

Sorry if you mistaken for the plugs in the Bantam Dac. The Bantam costs about 60$ to build as long as I know.

I'm meaning the ones in devilsound:

PenguinAmp also has a an USB DAC cable like that, far cheaper:
http://www.penguinamp.com/USB-DAC-Ca...cm::10067.html

 

[myinitialsaredac]

Thanks for the clarification but I assumed the eichmanns.
Quite pricy even compared to the srcas oO.

Dave

 

[1UP]

Although they externally look similar, to be fair to the Devilsound, there are several differences to the circuits that could justify its extra price over an Alien/Bantam; it's DC coupled, only uses the PCM2707 for USB-I2S conversion to the AD DACs, and has opamp buffered output...it should be a fair bit better than a straight PCM270x

Wonder if anyone can do a comparison...

 

[devilsound]

Hi guys,

I ran into this post just recently (finally, I got in on a thread at the beginning!), and I thought I might be able offer some insight ...

This is the first I've seen the Bantam DAC, and it looks quite nice. The PCM2702 which it uses is a premium USB receiver chip and D/A converter (I have an tube amp which uses the chip), and I imagine their circuit sounds excellent. For the price, and if you're into assembling yourself (or is there a pre-built version?), it would be quite hard to beat. Hats off to them for the circuit, and for publishing it as well.

Oh, and as for the pics displayed above of the compact enclosure, with the built in cables ... looks <cough> quite like something I've seen before. But hey, go for it! The all-in-one cable is a great form factor... do keep in mind, though, that the case on the devilsound DAC is a custom milled (CNC) aluminum enclosure, with no screws, and barely a visible seam (and laser engraved text). There’s quite a bit of engineering that went into it, I think it’s hard to appreciate until you see it in person.

As for the Penguin amp mentioned, I'm actually quite befuddled on their choice of the PCM2704. The THD+N of this chip is fully three times higher (or possibly six times higher, depending on how they implemented the power supply) than that of its cousin, the PCM2702. For $4 more, they could have used a chip with a high-grade D/A converter (the PCM2702 checks in right at the theoretical limit for 16-bit sound). Not sure what to make of this ...

Anyway, let me mention a few things about the devilsound DAC. I've never been a huge fan of CDs, thinking that they sounded a bit harsh and, well, "digital." … until I discovered NOS and, to make a long story short, started to enjoy the sound of digital recordings for probably the first time. (I'm not alone in my opinion on NOS, either.) From there came devilsound labs, and at the time we started especially, there was absolutely nothing like it on the market. (I still don't think there is, to be honest.)

Unfortunately, NOS requires a bit more than a single chip (especially if you put effort into a clean power supply). I mean, a LOT more. Our board is double sided, four layer (ground and power planes in the middle), and regenerates multiple clean, independent power rails (including a negative voltage rail!) from the USB power. There’s even a chip on there running our own firmware to make everything work together.

In total, the devilsound DAC has 24 different component types, and 63 individual surface mount components. (No kidding. The board is mounted by its edges, so we can fit all the components on both sides without anything touching the case.)

... thus, the price of the devilsound DAC. It's actually not a huge markup from the manufacturing cost, especially considering what typical markups are for audio electronics. And, it's not like we get 10,000 made at a time in China. (The whole thing's designed and manufactured in the US.)

Surprisingly, the Eichmann’s + silver wire aren’t the chief cost, by far ... to put it in perspective they cost about as much as getting all the components mounted onto the board. They're really nice plugs - light, simple, easy to work with and, well, I would say, worth it.

Anyway, we've been getting a lot of positive feedback on the sound. (Here's a post from one of our customers ), but not a lot of comments online yet …

I hope this helps. I’ll check back on the thread to see if there are other questions I can answer, or feel free to email me directly (contact info is on our website).

Jonathan
devilsound labs

 

[myinitialsaredac]

Devilsound thanks for the input, always nice to hear directly from the source.

I guess what one of my primary questions would be is what usb mode the DAC implements (adaptive, asynchronous).

Also could you expand on the word clock implementation, I didnt get a lot except that it is connected from the pcm2707 to the ad1851.

Finally what op-amp is used in the output stage?

Thanks,
Dave

 

[1UP]

Welcome to the thread, Jonathan. I wondered what if any other products you guys are planning - perhaps a head amp?

 

[devilsound]

Quote:

Originally Posted by myinitialsaredac /img/forum/go_quote.gif Devilsound thanks for the input, always nice to hear directly from the source. I guess what one of my primary questions would be is what usb mode the DAC implements (adaptive, asynchronous). Also could you expand on the word clock implementation, I didnt get a lot except that it is connected from the pcm2707 to the ad1851. Finally what op-amp is used in the output stage? Thanks, Dave

Dave:

> one of my primary questions would be is what usb mode the DAC implements (adaptive, asynchronous).

The receiver chip is a PCM2707, which, like all PCM270x chips, uses Burr-Brown's patented SpAct (Sampling period Adaptive controlled tracking) technology to recover a low-jitter digital stream from the USB port.

As far as I can tell, this is pretty much the dominant technology in the USB audio world. A full description of how and why it works would fill a three part series ... fortunately, that three part series has already been written, and you can check it out if you're interested in the details of USB audio transmission protocols, the problems with it, and the SpAct solution.

It's a great read if you're into the technical side of things ...

> Also could you expand on the word clock implementation, I didn't get a lot except that it is connected from the pcm2707 to the ad1851.

The PCM2707 (USB receiver chip) outputs the digital audio stream in I2S format, while the AD1851 (D/A converter chip), like a lot of DAC chips, takes an input in a right-justified format. Translating between the two is done with shift registers, to correctly align to data signal to the word clock, and also allows both channels to update simultaneously from a single unmodified word clock. This is done with a chip (a CPLD) running our own firmware.

As for the word clock signal itself, it goes, untouched, directly to the latch enable on the left and right channel AD1851 chips. This keep the signal to the latch enable on the DAC chips (where the jitter ultimately actually matters) as clean as possible, and precludes the possibility of additional additional jitter from intervening logic.

> Finally what op-amp is used in the output stage?

We use the op-amp that are built into the AD1851. This might come as a surprise to DIYers, but we had a protoboard that let us switch out whatever external op-amp we wanted, and found that the one already in the DAC sounded the best.

If you think about it, though it makes sense. The AD1851 chips are about $20 for a stereo pair, not at all cheap in the DAC world. So I don't think that they scrimped on the quality of the op-amps at all. Quite the opposite - I think Analog Devices probably put a lot of effort into finding the op-amp with exactly the characteristics they wanted (high-speed, low distortion, FET input, etc.) to match their DAC, and went with that.

Hope this helps. For those interested, but we have a bit about the DAC design on the webpage.

Jonathan
devilsound labs

 

[myinitialsaredac]

Thanks for the info =D
Have you taken any measurements on the associated jitter that you wouldnt mind sharing? =D

Dave

 

[devilsound]

Quote:

Originally Posted by 1UP /img/forum/go_quote.gif Welcome to the thread, Jonathan. I wondered what if any other products you guys are planning - perhaps a head amp?

Well, the idea with the DAC was that it fills an niche.

Especially when we started the design, non-oversampled audio was rare and expensive and generally not USB compatible, and the form factor (small electronics, single cable) had yet to be exploited. So, the DAC seemed like an obvious product ... basically, we started making them because we wanted something that didn't exist!

I think that the devilsound DAC still stands in its own category, although things are starting to fill in a bit ...

Headphone amps are a much harder field. There are so many people making amps of all kinds, all qualities, all prices, that it doesn't seem like a good place to put out another product, unless we have some different take on it.

So, hard to say what the next product is going to be.

There are also other ideas on the table, like trying to open-source a DAC design, and come up with something that people can generally agree is the "best" circuit, rather than have dozens of companies starting over from scratch and reinventing the wheel, and then spending all their money on adventising.

It's sort of an idea who's time has come, or will come. I mean, sites like this and others have gone a long ways towards that goal already, but there are still a number of hurdles. (Getting people to agree in the first place ... finding some incentive for manufacturers to give away their "secrets" ... how to properly credit / compensate people so they don't feel ripped off ... and so on.)

We'll have to see ...

 

[suna9828]

Quote:

Originally Posted by devilsound /img/forum/go_quote.gif Well, the idea with the DAC was that it fills an niche. Especially when we started the design, non-oversampled audio was rare and expensive and generally not USB compatible, and the form factor (small electronics, single cable) had yet to be exploited. So, the DAC seemed like an obvious product ... basically, we started making them because we wanted something that didn't exist! I think that the devilsound DAC still stands in its own category, although things are starting to fill in a bit ... Headphone amps are a much harder field. There are so many people making amps of all kinds, all qualities, all prices, that it doesn't seem like a good place to put out another product, unless we have some different take on it. So, hard to say what the next product is going to be. There are also other ideas on the table, like trying to open-source a DAC design, and come up with something that people can generally agree is the "best" circuit, rather than have dozens of companies starting over from scratch and reinventing the wheel, and then spending all their money on adventising. It's sort of an idea who's time has come, or will come. I mean, sites like this and others have gone a long ways towards that goal already, but there are still a number of hurdles. (Getting people to agree in the first place ... finding some incentive for manufacturers to give away their "secrets" ... how to properly credit / compensate people so they don't feel ripped off ... and so on.) We'll have to see ...

Jonathan, I commend you for being so open and frank about the development process of your USB DAC. It's usually not the norm for developers to share their knowledge to the public in simple, easy to understand, no-BS language. Even for a layman like me, I got the gist of what you're explaining, and it's quite an eye opener compared to all the other superfluous and flowery writing seen in other product descriptions and online audiophile magazines.

Do you plan on making a USB-to-digital transport anytime soon, preferably with spdif coax, toslink and I2S outputs?