[fattighjon]

Hi
i actually posted a similar question in the amp forum a week ago, looking for a dac/tube/headphone amp combo, but ive realised all those factors might limit me a bit, especially since im on a low budget, so i guess ill have to get the dac and amp separately. the dac is my primary concern, so thats why i post here.

i need something with:
*optical in
*good line out level (see below)
*under £200

preferably a tube dac, but they seem pretty rare? (at that price atleast)

ive read about the non-os dacs (tda1543?) which seem quite nice, but does that generate any problems if i try and play audio in another format than 44/16? (48khz is used on dvds for example)?? i will need something that can handle atleast 44 and 48khz

Im going to use it with a pair of active speakers (genelec). will i have to use a preamp aswell or should the output of the dac be enough?

i have nothing against second hand gear.


I also have a question about jitter that im sure has been asked before..
ive googled it and understood that its got to do with the sync of the clock somehow when transporting the signal from the computer/cd/iriver to the dac, but i just dont understand how it can happen? i can stream 1000kb/s of data from the other side of the world over a phoneline designed to only do analogue audio over a 2400hz spectrum without missing a single 1 or 0, but i cant transfer 150mb/s of data 50cm over a fibre connection that is designed for bitrates thousands of times higher?


cheers
G

 

[elnero]

In that price range I'd say a non-oversampling DAC might be your best choice. I use mine with a DVD player as a transport and have used it to watch movies but I have my DVD player set to output PCM only. This is something I don't have a very good handle on as yet though, I had always thought that a non-oversampling DAC could only accept a 44.1khz/16 bit signal but reading throught the description of the MHDT Laboratories Constantine on eBay it says Quote:

This is traditional DAC, cannot decode HDCD signal. The digital signal accepted is based the capability of CS8414 digital receiver which means the max: 96KHz in Spdif format.

So I'm gathering it can accept higher based on the reciever chip but maybe some of the more knowledgable members could elaborate further and correct me if I'm wrong?

Some of the non-oversampling DAC's have a passive I/V stage so they output a lower than standard voltoge. My Dialogue II is like this and the Monica 2 is as well but the Constantine and DAC-AH uses opamps in the output stage so it should have a standard output voltage. The passive stages might be a concern for you if you're using them with active speakers so maybe the best non-oversampling option for you could be a DAC-AH from DIYCLUB. It has a very low entry price of $135 + shipping, it uses an opamp output stage that can apparently be bypassed for better sound and the unit as a whole is proving to be highly moddable so future upgrades are possible.

 

[fattighjon]

Thanks
yes, the dac-ah seems very nice and its one im certainly condering.
my sources will be iriver h140 and computer (cheap usb-optical out will be enough? or maybe i should get an airport with optical output.. theres no degration there i hope?

cheers
G

 

[jefemeister]

Quote:

Originally Posted by elnero ... I had always thought that a non-oversampling DAC could only accept a 44.1khz/16 bit signal....

non-oversampling just means that the sample rate at the DAC is the same as the rate at the digital receiver. It also implies that the data is not filtered or processed in any way. A non-OS design can be capable of handling rates higher than 44.1, these rates could come from hi-rez material or possibly a rate conversion handled in a seperate box. For example you could hook a non-OS DAC up to your computer and do the 44.1->96 conversion in software.

 

[elnero]

Thanks Jeff!

 

[jefemeister]

Quote:

Originally Posted by fattighjon i can stream 1000kb/s of data from the other side of the world over a phoneline designed to only do analogue audio over a 2400hz spectrum without missing a single 1 or 0, but i cant transfer 150mb/s of data 50cm over a fibre connection that is designed for bitrates thousands of times higher?

Jitter does not cause bit errors because the slight timing variations do not matter in a digital system--everything is still being clocked on a rising/falling edge. Jitter exists on these clocks but it can be ignored because it doesn't matter if your 1 or 0 arrives picoseconds sooner or later than expected. Jitter would have to be obscenely big in order to cause a bit error.

But jitter is very important when converting from digital to analog domains. Jitter on the bit clock doesn't really matter (for the same reaons given above), it's the jitter on the word clock that is the big one. The word clock is the signal that tells the DAC when to output a new voltage level. If you tell the DAC to change levels at the wrong time it causes a slight skewing in the analog waveform. For instance, if you send a digital sine wave to a DAC with no jitter you will get a perfect sinewave out. If you do the same with jitter, you will get a sinewave where the slope is constantly changing slightly. This is audible.

It's hard to describe without drawing a picture. Think of the equation for a sinewave x = sin(t). With jitter it would be x = sin( (t-y) ) where y is a constantly changing random small number.

Hope it helps and doesn't confuse you more.

 

[Tom L]

If you want a more detailed explaination of jitter, there's an article by John Atkinson in the December 1990 issue of Stereophile magazine on the subject. It's on-line at:

http://www.stereophile.com/reference...ter/index.html

 

[Jahn]

If you want a Tube DAC that is non-oversampling in your price range, try the Scott Nixon Tube DAC+ here-

http://www.scott-nixon.com/dac.htm

I reallly like the sound, it's nice and warm yet still detailed, and the price is under $500.

 

[clarke68]

Quote:

Originally Posted by fattighjon Im going to use it with a pair of active speakers (genelec). will i have to use a preamp aswell or should the output of the dac be enough?

Regardless of the output issue, you'll still need to control the volume somehow...I don't know if your monitors have volume controls, but very few DACs do. If all you need is a volume control a simple passive preamp will suffice (I had fidaudio build me a passive preamp version of his Quintete Switchbox), a regular preamp will give you a little boost as well.

It's not a NOS DAC, but the California Audio Labs Sigma and Sigma II are pretty well regarded in the "less expensive used DAC" space. I don't know how easy they are to come by on your side of the pond, but they turn up on Audiogon every so often.

My favorite online article about jitter is here.

 

[fattighjon]

Yes
the tubedac+ is on top of my wishlist, but im afraid its going to be just a little too expensive for me, considering im also about to buy a pair of speakers
(unless theres second hand ones circulating, but who would want to sell their tubedac+???

maybe theres a tube mod for the dac-ah?

anyways... (i havent read that jitter link yet!) ive heard optical is worse for jitter.. how is that? couldnt you just put a buffermemory in the dac after the optics, with its own ticker, so whatever jitter the optics generate, doesnt affect the sound?
and say the clock is +-10% off in time on every tick, creating jitter... why not use a 10ghz ticker, and then just use every 1000000something tick for the d-a conversion, making that 10% superdupersmall?
or thats not how it works? (i suppose if it did, then someone wouldve done it)

cheers
/G

 

[blessingx]

Used TubeDAC+s show up on Audiogon pretty regularly. That's where I got mine.

http://www.6moons.com/audioreviews/nixon/tubedac.html

Depending how someone planned to get the signal to it, it may require an additional card, etc. (more cash).

 

[fattighjon]

yes,
there is one right now, $400 with the PS and extra tubes, but im not sure its going to be worth 3x the price of a dac-ah. maybe the money is better spent on stepping up one model on the speakers..

cheers
G

 

[blessingx]

People still use speakers?

 

[TigzStudio]

Zhalou 1.3 fully modded is freggin sweet....!!! especially for the price.

 

[yo2tup2]

Quote:

Originally Posted by TigzStudio Zhalou 1.3 fully modded is freggin sweet....!!! especially for the price.

a second that!

except that part about "especially for the price." i say its an awesome dac period!