All the DACs money can buy, pt. 2
May 16, 2008 at 8:05 PM Post #19 of 198
Thanks for the continued updates! If you find more than one DAC, please use Edits on your post instead of multiple posts--it will be less cluttered that way.

Edit: All DACs mentioned so far have been added, and I have a few more to add later as well.
 
May 16, 2008 at 10:25 PM Post #20 of 198
got another one to add, which is the DAC I just bought the Promitheus DAC (TDA1545A) $405 which can be found at Promitheusaudio Solid State DAC

Also the HotUSB1 $79.99 which can be found at HotUSB1 USB DAC High-Performance Headphone Amplifier

and USB DAC High Fidelity Digital Stereo Headphone Amplifier $155.99 USB DAC High Fidelity Digital Stereo Headphone Amplifier

Not sure this one counts but you can get the alien DAC kit for $42.90 Glass Jar Audio

edit: just read your post above, otherwise I would have added this to the last post I created. sorry
 
May 16, 2008 at 10:50 PM Post #21 of 198
Quote:

Originally Posted by wordsworth /img/forum/go_quote.gif
edit: just read your post above, otherwise I would have added this to the last post I created. sorry


No problem, it's only recommended to edit if yours is the most recent post, and since it wasn't in this case, it made sense to post again. Editing a post instead of multiple posts in a row will keep the post count down so that the thread doesn't grow too large too quickly.
smily_headphones1.gif


I didn't know anyone still made the Alien DAC--thanks for that. This list could use more sub-$100 DACs, if they exist.
 
May 16, 2008 at 11:01 PM Post #22 of 198
great thread! thanks for keeping it current.
 
May 19, 2008 at 2:38 PM Post #23 of 198
Wow! You worked really hard!!! Great job, now I just have to figure out which one to buy
smily_headphones1.gif
Or two... heh
Mike
 
May 19, 2008 at 3:09 PM Post #24 of 198
FYI - the Alien DAC (first one in the OP's list) does not use an opamp for its signal output. The output of the DAC is directly coupled through a pair of output capacitors - most often Black Gates, Elna Silmics, or Muse ES's. On occasion, boutique film caps are used, too.

There is an option to use a BUF634 or OPA551 as a buffer (IC4) to convert the power from a virtual ground amp into something usable by the Alien DAC - so that the DAC may be powered directly by the amp. For all other power options (USB-powered, battery, amp w/o virtual ground), IC4 is not used at all and it is not installed. In any event, it has nothing to do with the signal if used.
 
May 19, 2008 at 3:38 PM Post #25 of 198
Along those lines, what exactly are the differences between "discrete output," "class A discrete output," "passive I/V," "active I/V"? It's a little unclear in my mind which methods, if any, avoid the use of op-amps in or out of the signal path.

Quote:

Originally Posted by SirMikeAloT /img/forum/go_quote.gif
Wow! You worked really hard!!! Great job, now I just have to figure out which one to buy
smily_headphones1.gif
Or two... heh
Mike



Thanks! Maybe we'll see similar "all the x money can buy" threads cropping up. Headphones, amps, speakers, transports, CD players, etc.
 
May 19, 2008 at 11:49 PM Post #28 of 198
Quote:

Originally Posted by jinp6301 /img/forum/go_quote.gif
The pico has a 1/8th output not a TRS
smily_headphones1.gif



Whoa, that is small. I tried to guess based on size, and 1/8" jacks mean it really is 'pico'-sized. Updated.
biggrin.gif
 
May 20, 2008 at 2:00 AM Post #29 of 198
Quote:

Originally Posted by infinitesymphony /img/forum/go_quote.gif
Along those lines, what exactly are the differences between "discrete output," "class A discrete output," "passive I/V," "active I/V"? It's a little unclear in my mind which methods, if any, avoid the use of op-amps in or out of the signal path.


Passive I/V = a resistor is used to convert the output current from the DAC ("I") to a voltage ("V") that can be used to provide a line-level signal. This is sometimes a less-than optimum solution because every ohm in the resistor adds noise, but the output voltage is very low unless you raise the ohms. A happy medium is often selected, but is far less than optimum. This is the cheapest form of obtaining a usable output from a DAC.

Active I/V = same principle as above, only an active circuit is used. It's sort of analogous to an amplifier, but not really because the circuit is used to provide I to V conversion instead of gain and current buffering. IOW, it gets the very small current output from a DAC up to a signal voltage with a very low output impedance. This means the signal output can achieve line-level voltage with a very flat frequency response - best solution.

Discrete output - this is a form of Active I/V. Non-discrete is an opamp. Opamps are frowned upon by many audiophiles. They bring their own flavor to the circuit, adding some tizziness, filtering a lot of the detail with their protective circuitry, etc. A discrete output, Active I/V is analogous to a discrete buffer in an amp - a bunch of transistors everywhere with not an opamp in sight. It's very labor intensive to build and expensive to buy, but offers the best in detail and DAC output.

Class A Discrete output - this takes the Active I/V, discrete output one step further and adds a Class A bias - meaning an active current that always keeps the transistors turned on, removing any possibility of switching noise. This is the ultimate in solid-state, discrete audio output. (But it burns heat and usually comes with heat sinks and ventilation.)

There's probably some of the above that can be argued in terms of specificity, but I think it states the gist of the terms you asked about.
 

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