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Introduction to the Compass DAC and Headphone amplifier

post #1 of 31
Thread Starter 
Introduction to the Compass DAC and Headphone amplifier.
Important: If you want to know about shipping or the status of your order, you need to contact Audio-gd. Nobody on the forums knows, only Audio-gd does! Please don't forget to check Audio-gd's web site for the latest info, including shipping times.

The History of the Compass: (Read this specially if you're new to audio gear and Head-fi.)

Like many people, back when I took an interest in Head-fi, I'd been using a good pair of headphones straight out of my computer. As the pads on my headphones had worn out, I was considering a new pair of headphones to replace them. With a budget of about $200-300, I headed to the local electronics shop to try out a few pairs, but thought I'd read around Head-fi to see what people liked. Like many other people, as soon as you ask about half-decent headphones, someone chimes in with "But you'll need a decent amp to drive them.". So you start looking for a decent amp. Then someone chimes in, "If you get an amp, you'll need a decent DAC too, your soundcard wont be good enough". Ok, so that makes what I need not just $200 for headphones, but a couple of hundred for an amp, and the same again for a DAC. Ouch.

With decent headphones, you need an amp because it can drive the diaphragms of the headphones much better than a crappy sound card (or CD player). You need a dedicated DAC (Digital to Analogue Converter) because your sound card, even if it's a good one, is seriously compromised so that it will work in a computer, not to mention will pick up a lot of interference from other components.

However, rather than having to buy two components, some companies make an all-in-one device that is both a DAC and a headphone amp. You buy one box, plug it into your computer, plug your headphones into the box, and you're set. The most popular device for doing this on Head-fi is possibly the Zero DAC. Made in China, costing only $99 and, most importantly, sounding good, it was a hard purchase to argue with. What's more, over year, a number of people experimented with modifying it to improve the sound. This was easy because a couple of critical components (known as OPAMPs) could be popped out of their sockets and replaced with many of the thousands of others on the market. This got to the point where even the eBay sellers were modifying them and shipping them to customers for up to about $220. That's quite a jump from $99, but so was the sound quality.

However, after a while there were problems. People were receiving these units not working, with stupid mistakes as as the OPAMPs inserted in backwards (destroying them) or in one extreme case, burning up someone's headphones. This was not cool.

During various people's search for upgrades, we came across a company called Audio-gd, who makes, among other things, an OPAMP called a HDAM. It made quite a nice improvement to the Zero. Not only that, the owner, Kingwa, is a very receptive and enthusiastic man, and took on board a couple some suggestions about his designs. Audio-gd also makes other hi-fi gear, including a couple of headphone amps, so, after another head-fi'er blew up at me asking why I still had a link to an eBay seller in the Zero FAQ who'd had a couple of major customer issues, I decided to do one better, and asked the owner of Audio-gd if he could make something similar to the Zero, for about the price of a fully-upgraded model. Since I'd already bought and was satisfied with the quality of one of his headphone amps (the C2C), and a couple of other head-fiers who'd bought gear from him were pleased with both the quality and his customer service, if he could make such a unit, then there'd be a decent all-in-one solution for people, who, as I was when I started, were looking for a decent but inexpensive head-fi solution. This became the Compass.

One of the important things here is, Kingwa has assured me that he will absolutely not compromise quality, even if he becomes popular on Head-fi. I previously have bought products that were "flavour of the month" on Head-fi and when I received one from another company, it had obviously been rushed to be assembled, with poor casework and screws not aligned properly. The result of this is, you may have to wait a couple of weeks after ordering to get a Compass, but you will receive a unit made with the highest attention to quality.

Ok, so what's the damage to my wallet going to be?

As a promotion, Kingwa has said that the Compass will be sold at cost until May 2009, for $258 + shipping. From June 1st, it will be $330 + shipping.

What does it do?

The Compass has two parts inside: A Digital to Analogue Converter (DAC) and a headphone amplifier which can also optionally be used as a volume control (pre-amp) for a hi-fi system or similar.

What can it do for me?

Sound a lot better than plugging quality headphones into your soundcard or CD player, mainly, but other than that:

In what I'll call "normal" mode, you plug it into your computer or CD player's digital output, via USB, coax (RCA), or optical (Toslink) at the back, plug your headphones in the front and enjoy the music.

Engaging the Super switch disconnects the DAC and the headphone/pre-amp from each other. The DAC then can be used by itself from the DAC out sockets. The headphone/pre amp can also be used by itself, from the Line In sockets. Both can be used at the same time this way. As a matter of fact, if you connected a cable between the DAC out and Line In, then Super mode would be exactly the same as normal mode.

If you're confused, try this diagram:


In either mode, the "pre-amp" switch at the back diverts the headphone output to RCA Pre Amp jacks at the back instead.

Which is best, USB, coax or optical to connect it to my computer with?

You'll have to experiment. If you have problems with hearing computer noise connected using USB, using a sound card with an optical socket might fix that. Ideally whatever connection you use shouldn't have any software or hardware in your computer altering the sound.

Using USB will use the standard USB audio drivers in Windows, Mac OS X or Linux to recognise the Compass. Coax or optical digital is "dumb" and just sends the digital signal.

If you don't already have a good sound card with good drivers, you may want to try the USB Asio driver. It's not free, but you can download it to try. For some people it makes a large improvement with the Compass over USB. It probably wont make a difference if you use a Mac.

For information on the sound settings in Windows, see this guide. There's nothing to set up on a Mac (if you're just using CD-quality music).

What is the HDAM/OPA?


Long story. It's an amplification circuit for the DAC section. Audio-gd has three designs, the Earth, Sun and Moon. Each have a slightly different "voice", with the Earth being the closest to neutral. Switching them allows you to tweak the sound slightly.

For the technical minded who want to know the voltage range for opamps, Kingwa has stated: "Compass use ±16V for OPA, this range can support most OPA chips."

Which HDAM/OPA is best for me?
You can read majkel's review of them here, which should give you some idea. dBs also wrote up his experiments with them and the soft/bright settings. Most people also buy the Moon, or Moon and Sun. The nice thing is, when you get bored, you can switch them around and enjoy something different for a while. Their sound changes over the first 350 hours of use (as they burn in) too.

Do I need to do any soldering to change the OPA/HDAM?
No. You only need a phillips screwdriver for the ground wire. The HDAM/OPA itself goes in a socket.

My stickers have fallen off, which HDAM is which?
If your stickers fall off, see the picture of the Earth, Sun and Moon above respectively. The Sun is the only one with glowing diodes, and the Earth is the only one with the bracing wire at the very top, between 4 vertical transistors.

How does it compare to other similar things from other companies?

Its "sound" is very similar to the Zero, but because of the much better components and better design, the sound quality is much better. For other comparisons, they'll be added as people write about them.

It's value though is very good. In my old system, of a Northstar DAC ($2500 new or ~$1000 second hand) + Audio-gd C2C amp ($330) + 2x Audio-gd power cables ($75 each) is not anywhere near 6x better than the Compass. I would say it would take around $1000 or close to it to (new, not 2nd-hand prices) get a significant improvement on sound quality, say, from a Lavry DA-10 or Benchmark DAC1, but then you wont have half the options available.

What's the next step up from a Compass?

If you're talking about from Audio-gd, it'd be a DAC 19MK3 and a C2C headamp, which comes to something like $800, before you add good power cables and interconnects.

Burn in:

The sound of the Compass and especially the OPAs takes at least 350 hours to settle down, though not truly until after 600 hours of use. Until the 350 hour mark, there will a few weird sonic changes, such as the treble on the OPAs dropping off around the 250 hour mark, then returning somewhere around 300 hours. See this post (direct post link) by Pricklely Peete for more info.

Reviews and comparisons are here: (Edit: Thread links are/were broken so have been removed.)

Sanchak compares it to his CD players: | Post
Joeoboe's review: Post
Pricklely Peete's epic review Pt1 including how it fares as a pre-amp: Post
mbd2884's review with AD900s and the Audio-gd power cable: Post
Currawong: My comparison of the DAC to the Benchmark DAC 1: Post
Drosera compares it to the Meier-Audio Corda Opera: Post

The impressions of the upgraded unit (same electronics as the final unit but with the old case) start from this post on page 277 (if you're viewing with 15 posts per page).

dBs: Compass vs. XFi for gaming: Post
mlarn: Initial impressions: Post
direcow took his to a headphone meet in Singapore: Post
techfreakazoid wrote up his initial impressions: Post
theBigD compared it to his EF1: Post
slim.a writes about the differences between the Compass and EMU0404: Post
bjorn compared it to his Musical Fidelity V-Can. Thread
dBs wrote up his OPA/HDAM and soft/bright settings experiments: Thread
Zanth wrote his initial impressions: Post
ttv posted some good pictures of his compass.
ecclesand compared it to the OMZ DAC: Post

Other reviews:
theBigD: Compass vs C2C / Compass DAC vs Stello DA100 Review and Comparison

("Thread" links to the post in the thread, "Post" links to the individual post page only.)

Purchasing and other info:

To purchase, you should contact Audio-gd using the email address on their web site with the details of what you want and your address. They will then reply with a quote.

The tracking number emailed by Audio-gd is one that's printed on the consignment note attached to the package. It will only work online once the package has been processed by an EMS or DHL office, both of which are some distance away in Hong Kong. This takes a few days.

Their web site sometimes goes down briefly, as their web host is unreliable.

post #2 of 31
Can we use just the DAC feature of the compass so we have a selection of 2 amps and 2 dacs (if currently running from a soundcard)?
Keep up the good work.
post #3 of 31
Thread Starter 
Originally Posted by m0ofassa;bt995
Can we use just the DAC feature of the compass so we have a selection of 2 amps and 2 dacs (if currently running from a soundcard)?
Keep up the good work.
Yes, that's right. In "Super" mode, you can use just the DAC, or just the headphone amp.
post #4 of 31
Is there a direct review of the compass against the Zero?
post #5 of 31
How about this vs the Keces DA-151
post #6 of 31
Thread Starter 
nsx_23: The Compass sounds like a much better version of the Zero.

Baird_GoW: Buy me one and I'll compare them.
post #7 of 31
Thanks a lot for this intro. It helps . Is there a limit to the number of quantity that will be sold at this introductory price before May 2009? I see the words 'final 30' and 'being on the list' in many places and it made me wonder.

It would be great to get it at the intro price, however I just want to wait for some reviews/comparisons.
post #8 of 31
Thread Starter 
I don't believe there is any limit to the number that will be sold. The "final 30" referred to the version prior to the changes to the front and back face plates. People are starting to receive the final version now, so keep watching the main thread for impressions.
post #9 of 31
Also noteworthy is that Kingwa is developing a matching poweramp to go with the compass, for those that want to use it to drive speakers.

Which brings up another point, which is that Compass can be used as a preamp as well. One of the reviewers focused heavily on this function and was quite impressed with it.

Full disclosure: I haven't heard the compass yet, but as I just ordered mine a few minutes ago, I'm convinced that this is quality gear.
post #10 of 31
In order to use Coax/SPDIF do you also need to have the unit connected on USB, like for installing drivers or detection by Windows?
post #11 of 31
Thread Starter 
Coax/SPDIF has nothing to do with Windows or drivers. If your sound card has a coax digital output, then you would select that as the output as required.
post #12 of 31
If I understand you correctly, you say that I just connect the Optical Out of my card to the Optical In of the Compass and the signal will be processed by the Compass' DAC? No need to change anything in Windows and no need to connect via USB initially?
post #13 of 31
Thread Starter 
Optical digital only carries optical digital data. Coax digital is the same, just the signal is carried over wire instead of plastic or glass. There is no "device detection". All that happens is the Compass locks onto the signal.

This doesn't mean that you don't have to set up the soundcard's software to output digital or bit-perfect digital as required.

USB on the other hand uses device detection, where the computer gets information about a device over the connection, along with what speed it is so that it can select the appropriate driver to control it.

Optical connections are blind, in that the receiver doesn't send data back. Neither does a SPDIF or AES/EBU connection. A sound card might be set up to detect that something has been electrically connected, but not what device it is. It might take a guess from the impedance of the device, but that's about it.
post #14 of 31
Dear All,
I withdrawn my comments as it has been proven that it is not so.

I would like to apologise for the misunderstanding and thanks all for helping me understand what is going on.
post #15 of 31
Thread Starter 
I think gadenp didn't realise that nobody has received the final unit yet!
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