Jitter reduction, best device?

Rbstehno,

I know a PC can provide a good digital source because I am doing exactly that in my system alongside feeding from a CD player/transport.

In my case though the true source from the DACs perspective is the Roku Soundbridge, which is a device designed for good sound at its price point. The laptop computer source is not even known to the DAC.

I do think it is more hit or miss from computer to computer in general though, depending on details and specific configuration and topology, because different components and interface implementations exist in different computers and many, particularly older ones, are not necessarily designed for performance levels that audio buffs expect.

For $200, the Roku or other devices like it like the Squeezebox take source computer mostly out of the equation regarding sound quality, so it is a good approach in my mind.

Not to say some computers may offer up great sound directly as well. I'm sure some do but I'm not sure that all do.

I started out at first with an analog feed from my computer to my system. That was a halfway decent but ultimately flawed approach. Where I am at now is pretty much where I think most audiophiles would like to be.

"do you think that reading music off a cd player is any different than reading bits off a cd when loading a program onto your pc? "

No. Reading music versus other kinds of files from a CD optical, magnetic hard drive or even physical menmory is no different at all.

But re-constructing an analog signal in the DAC, based on the clock, is an additional scenario that comes into play after wards in digital sound reproduction. I believe different sources do this differently with varying degrees of accuracy. For example, USB uses a software driver. Some may be better than others I would suspect.

The result if the bits are not processed at the DAC at exactly the right time is jitter, as I understand it, and jitter frequencies and levels do affect the resulting sound.

I was HIGHLY skeptical about the Monarchy DIP but recently tried a DIP Classic (no upsampling) in my system and was very impressed with the results. I use a Monarchy DAC 24 with Matsushita tubes, Ayre AX7e and Green Mountain Europas, either an inexpensive Integra player or Cambridge audio DVD player for transports.

The results were as dramatic as changing tubes. The separation and clarity was increased, vocals in harmony became much clearer, cymbals more sonorous, and room reverberation or reverb sounded much more integrated. I did not experience this as a softening of transients, more like a layer of grit being scraped away. Another audiophile describes this as a window that had been cleaned.

As I said, I was very skeptical and spent a lot of time doing real time switching comparisons with a variety of music.

It does seem as though this function should be built into a well designed DAC. My understanding is that the newer DAC chips that parellel inputs do not have significant jitter issues.

Yes, Virginia, jitter reduction devices are still alive and kicking ass! I currently use both the classic but alas no longer available Genesis Digital Lens (from PS Audio) and the Audio Alchemy DTi-Pro 32 jitter reduction devices with great effect, using them not with CDs but with high inherent jitter digital sources such as XM/Sirius satellite radio. Both work very well, but the Digital Lens has a narrow edge in sound quality and more inputs (5 vs 3). These devices went out of favor starting about ten years ago when stand alone DACs and CD players began to have more effective jitter reduction circuitry built into them. However, even most current DACs that have jitter reduction circuitry are designed only to handle the levels found in CD drives which are much lower that those found in satellite radio or many computer interface devices. Therefore, I (and others I know) have resurrected my Digital Lens and AA DTi-Pro and send the digital signal from my Polk XM tuner to them (in two different systems) , via its digital outputs (either optical or coaxial--coaxial, Wireworld, is better, but the Wireworld glass optical Toslink cable is amazingly a close second!) and thence to my DACs (one system has an AA DAC and the other a Theta DAC). The reduction in jitter and hence improvement in sound quality on the best of the XM stations is nothing short of astonishing. I have gone from barely being able to tolerate more than half an hour listening to XMs jazz and classical music stations, to listening to them for hours on end. Except for the still somewhat reduced or narrow stereo channel separation (similar in effect to the "blend" setting on FM tuners--somewhere between mono and stereo), the sound is VERY close to the best CDs in almost all respects. Jitter, apparently, more than just signal compression protocols, is the far bigger culprit to poor sound quality from satellite radio. Because satellite radio uses 3 different compression schemes, depending on the station (talk and news/weather being the worst, with jazz, classical and "classic"standards stations being the least compressed) reducing jitter alone will not improve substantially most of the stations. However, on the best or least compressed stations, whole new worlds of sound open up.

Interestingly, PS Audio is about to reintroduce a stand alone Digital Lens jitter reduction device because of the many new digital audio sources that are being used, especially in regard to computers, but which have higher jitter rates than most stand alone DACs can substantially reduce or eliminate. I have read several blogs on the advantages of using jitter reduction devices along with the Wadia iTransport/iPod and various music server devices, but I have not seen anything elsewhere regarding the benefits to sound quality from satellite radio or satellite/cable set top boxes (STBs), many of which have digital outputs. I have heard considerable improvement in sound quality from a Comcast STB when used with an AA Dti-Pro, but Verizon's Fios optical cable STB will NOT output LPCM thru its digital outputs--only DDS which neither the AA Dti-pro nor Digital Lens can handle (nor can most stand alone stereo DACs).



Unfortunately in regard to satellite radio, Polk has stopped manufacturing its XM tuner and it is only available now through the used market. I do not know of any other satellite radio tuners that have digital outputs, except for the mega buck Magnum-Dynalab units. The Polk tuner used by itself improved the sound of XM radio somewhat, but not anything like the improvement using its digital outputs and a jitter reduction device. I obtained some improvement in sound quality by going directly to the DACs from the Polk, but not nearly as much as using the jitter reductions devices in the path.

Astro,

I used to have a Theta TLC into two Pro 32's then changed to the '32's with a Digital Lens. It's better to use two Lens' in tandem since the chip thethe PRo 32 is no longer supported by Dusty Vawter. If it burns out, that's it.