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DAC What it Does, How to Use with a Computer For Bitperfect Sound

post #1 of 10
11/19/12 at 6:46am
Thread Starter 

 I went and got the Waspai plug in, went into my FooBar and put the output as Waspai EVENT 24bit 92000 herz, and enabled that. I then went into my windows and went into the Sound options for the HeadPhone out and under advanced I enabled "event" control and also switched into 24bit and 92000 herz in windows as well...

 

So seeing as I've done this, if I plug in my DAC, will it just work? Or are there some extra Steps. I Would also like to know how the DAC converts the bits into analog as well as how it communicates with my computer to get those bits into the DAC...

 

Truth be told, we are planning to start selling Audio Gear in our computer shop, and I figured I should first learn how, what and why to set up my own DAC driven system at home before I start explaing to our customers why and how they can do as I've done at home!


Edited by Mshenay - 11/19/12 at 6:57am
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post #2 of 10
11/19/12 at 7:07am

Sorry, I misunderstanding !


Edited by Migou67 - 11/19/12 at 7:46am
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post #3 of 10
11/19/12 at 7:23am
Quote:
Originally Posted by Mshenay View Post

So I'm interested in getting a DAC, but how exactly does it work... and how do I get it to work with my pc.

 

I know that a DAC, takes digital bits of information and converts them into audible Analog sound... but how does the Hardware work with the Software to do that...

 

You tell the software Foobar/etc to output a digital not analog signal - if your computer has a card/chip with digital output you use the Media software "Preference" settings to set the output to "digital".

 

700

 

If your PC does not have a digital output you will need to use USB. With USB the data is in packets and the receiver unpacks the data and sends it to the decoder. This option is popular as many (older) PCs do not have other digital audio outputs. Of course the DAC needs a USB input but that is quite common, even my $90 Fire Phoenix has USB.

 

The other common PC format is as optical (aka Toslink) signals. The light pulses contain the audio data as a stream of bits coded as pulses - if you look (not directly) at a Toslink cable connected to a digital output you will see the light (pun). On a PC this optical output may be on a full sized optical output or may be shared with the analog headphone socket (common on laptops).

 

For full sized Toslink the cables are cheap and easy to get. For laptops with shared headphone/digital you need a cable with an optical mini jack at one and and a normal Toslink connector at the other

 

 

700

 

The other common option is coax - a 75 ohm cable that looks like half a pair of RCA cables. Though this is rare on personal computers.

 

 

 

I have FooBar2000 with a Waspai Plug in and well I'm not sure how to utilize the Waspai plugin either... do I even need it if I'm going to be using an external Dac

 

 

 

So I have some questions and I'd love some technical answers, that way I can have a better understanding of how,what and why I'm planning to use an external DAC

 

Thanks guys <3

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post #4 of 10
11/19/12 at 7:31am
Thread Starter 

I have a TosLink Optical Spdif out, once I buy the cord do I just run it into my DAC? Or into the an Amp...

 

In addition I'm looking at using a O2 DAC, do I choose the Null Out option In FooBar then hook up the USB to the O2? and ofc from there I'd run it to my Amp

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post #5 of 10
11/19/12 at 9:17am

It doesn't matter if you use optical out (the device in Windows is usually labeled something like "digital out") or USB. Either way, you need to connect the cable to your DAC. Some amps have a DAC integrated.

 

The DAC will receive the digital signal and convert it into an analogue signal. This signal is usually weak and cannot be used to drive headphones directly. Therefore you connect the DAC to an amp, which will apply voltage gain (=> higher volume) and current gain. Again, your device might have both a DAC and amp in it. In the case of a sound card the transfer of digital data takes place inside the PC over PCI (Express).

 

To output to this DAC or sound card you need to set the proper output device in foobar2000. There are several different choices for audio APIs (in simple terms a software interface to communicate with the audio device):

- ASIO: was developed for recording, low latency (which is not a requirement for music playback), provides exclusive access to the sound devices (no mixing with system sounds or other applications)

- WASAPI: new interface by Microsoft, can provide exclusive and shared access (the fb2k plugin provides exclusive access only) to the sound device

 

With these two you can only set the bit depth (16, 24 or 32 bits, use the highest supported bit depth for your device). The sample rate (for example 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz ..) will be set to the sample rate of the track you are playing. If your DAC doesn't support this sample rate you'll get an error message and playback will fail.

 

- DirectSound (short DS): legacy interface by Microsoft, still works perfectly fine though, on Vista/7 it is implemented on top of WASAPI shared mode (mixing with system sounds etc.)

 

With DirectSound you have to set both bit depth and a common sample rate in the control panel. This common format is used for all sounds from all applications which will be mixed together and sent to the DAC. But DirectSound can also be bit-perfect if you set the common format to the same format of the track you are playing. Otherwise, there will be resampling (sample rate conversion).

 

 

 

Quote:
Originally Posted by Mshenay View Post

I have a TosLink Optical Spdif out, once I buy the cord do I just run it into my DAC? Or into the an Amp...

 

In addition I'm looking at using a O2 DAC, do I choose the Null Out option In FooBar then hook up the USB to the O2? and ofc from there I'd run it to my Amp

O2 DAC is USB only, no optical input. The null output is a special device that does nothing. It's used for development.


Edited by xnor - 11/19/12 at 9:23am
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post #6 of 10
11/19/12 at 9:58am
Quote:
Originally Posted by xnor View Post

 

The DAC will receive the digital signal and convert it into an analogue signal. This signal is usually weak and cannot be used to drive headphones directly. Therefore you connect the DAC to an amp, which will apply voltage gain (=> higher volume) and current gain.

is the signal weaker then headphone jacks on a laptop (typically i mean, i realize this must vary)? theoretically, if i only use an amp and no dac and usually set the volume on my amp to 3 (for arguments sake), would i need to set a higher volume if the signal is coming from a dac?

 

i hope i was clear...

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post #7 of 10
11/19/12 at 11:02am
Quote:
Originally Posted by adamlr View Post

is the signal weaker then headphone jacks on a laptop (typically i mean, i realize this must vary)? theoretically, if i only use an amp and no dac and usually set the volume on my amp to 3 (for arguments sake), would i need to set a higher volume if the signal is coming from a dac?

 

i hope i was clear...

There's two different things. Let me clarify.

 

A DAC may output a 2 Vrms signal (which theoretically would be plenty for a lot of headphones) but cannot provide much current. This means that you can only drive a high impedance load, such as the input of an amp (usually around 10 kOhms).

 

An amp with, lets say, a voltage gain of 1x (= 0 dB) will output the same voltage that is applied at the input, but can provide a lot of current. Enough current to drive 30 ohm or lower headphones.

 

 

I've seen laptops that can only output 0.3 Vrms max in which case most DACs will output a hotter signal. So you would actually need to set the volume lower with a DAC, or change the gain of your amp to a lower value.


Edited by xnor - 11/19/12 at 11:06am
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post #8 of 10
11/19/12 at 3:14pm
Thread Starter 
Quote:
Originally Posted by xnor View Post

There's two different things. Let me clarify.

 

A DAC may output a 2 Vrms signal (which theoretically would be plenty for a lot of headphones) but cannot provide much current. This means that you can only drive a high impedance load, such as the input of an amp (usually around 10 kOhms).

 

An amp with, lets say, a voltage gain of 1x (= 0 dB) will output the same voltage that is applied at the input, but can provide a lot of current. Enough current to drive 30 ohm or lower headphones.

 

 

I've seen laptops that can only output 0.3 Vrms max in which case most DACs will output a hotter signal. So you would actually need to set the volume lower with a DAC, or change the gain of your amp to a lower value.

Boy o Boy Direct Sound cna be shared AND bit perfect! Awesome sauce. That makes thing easy for me as Waspai makes my Games crash e.e, and setting bit perfect to 24bit 96 sampleing does show MINIMAL improvements... not to much really. Still good ot know DS can do Bit Perfect, so again if I get a DAC can I still used Shared sound, like getting the sounds from my MMO and FooBar together at the same time. I'd prefer only FooBar to go through the DAC, but if BOTH went through that'd be no big deal really

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post #9 of 10
11/21/12 at 12:49pm
Quote:
Originally Posted by xnor View Post

There's two different things. Let me clarify.

 

A DAC may output a 2 Vrms signal (which theoretically would be plenty for a lot of headphones) but cannot provide much current. This means that you can only drive a high impedance load, such as the input of an amp (usually around 10 kOhms).

 

An amp with, lets say, a voltage gain of 1x (= 0 dB) will output the same voltage that is applied at the input, but can provide a lot of current. Enough current to drive 30 ohm or lower headphones.

 

 

I've seen laptops that can only output 0.3 Vrms max in which case most DACs will output a hotter signal. So you would actually need to set the volume lower with a DAC, or change the gain of your amp to a lower value.


cheers =]

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post #10 of 10
11/26/12 at 6:26pm
Thread Starter 
Quote:
Originally Posted by adamlr View Post


cheers =]

hanks for the help! 

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