brodricj, the DirectStream Senior is an upgrade option above a DirectStream Junior.
norton saidbrodricj, the DirectStream Senior is an upgrade option above a DirectStream Junior.
I know. Iāve owned both. I prefer DSJā¦actually DSJ is my 3rd preference choice at home. Esoteric is first, Ayon is a close 2nd, then DSJ, then Krell ā¦but the DSJ gets more time in use than all the others put together.
Ted Smith said
..I get a kick out of "Rubidium clocks" in ovens for audio. The temperature doesn't change in a crystal fast enough to affect the phase noise that we care about for audio (or at worst adding just the insulation from an oven based crystal will do the same thing as a full oven as far as audio is concerned.)The purpose of the oven is to keep the oscillator crystal at a constant temperature whether the clock is in use or in standby. So the clock frequency is stable and good to go straight from standby mode to ON without having to go through a lengthy warm-up period. When using an external master clock the sound does change from a cold start over the next 20 minutes or so until the internal temperatures have reached an equilibrium. Some owners take the master clock to another extreme by connecting its external clock input to a 1 pps GPS reference source. So you have the GPS connected to the master clock which is connected to the source devices. One thing is for sure, in my installation at least, using the external master clock really does add a 3-dimensional experience and pinpoint tight focus that is just not as evident without it.
I think PS Audio made the right choice in building the DS/DSJ at the price point that they did, with the performance achieved at that price point. Itās a credible piece of hardware at an affordability point that gives it a much wider distribution than those far more expensive SOTA DACās.
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Ted Smith saidWe definitely are not at the limits of the current hardware. I was just taking the first question literally and answering it. I know that the next release will further improve the sound quality and Iām pretty sure I can make a noticeable improvement after that too.
This is exciting newsā¦ Your last rabbit was amazing (and Iām not going to say where you pulled it from)ā¦ butā¦ since it has been brought upā¦ and I certainly didnāt want to touch on the subject TOO early after Huronā¦ but - is this something in the current pipelineā¦ and would it be several monthsā¦ 6 monthsā¦ a year down the road ? Just not sure what other tidbits are getting thrown your wayā¦
The DS is an amazing pieceā¦ I donāt think I have heard anything but positive thingsā¦ BTW, if you havenāt seen itā¦ Charles Hansen went on a huuuuge rant on the comparison of the Benchmark to the DS in one of the latest ragsā¦more or less claiming the reviewer had potatoes in his ears. It is over on audioasylum in the Digital General sectionā¦
The crystal is always on in a DS or DS Jr and the chips near it that are warm are always on.
But my point is that an oven is irrelevant for audio because drift in frequency over times longer than, say, seconds is irrelevant to audio. Itās drifts on the order of, say, less than a second that affect the perception of audio and temperatures canāt change that much in a second. Rubidium (and GPS, etc.) technologies are very important for long term accuracy, but they sacrifice some short term accuracy to achieve their goals (otherwise the system temperature wouldnāt make such a difference.) Rubidium and GPS can only make a crystalās short term accuracy worse (tho perhaps not too much worse.) Spending money on shock absorbers for the crystal make a lot more sense than spending for long term stability.
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timm saidBTW, if you havenāt seen itā¦ Charles Hansen went on a huuuuge rant on the comparison of the Benchmark to the DS in one of the latest ragsā¦more or less claiming the reviewer had potatoes in his ears. It is over on audioasylum in the Digital General sectionā¦
Mind posting a link to it? Couldnāt find it at all.
I assume http://db.audioasylum.com/mhtml/m.html?forum=critics&n=88730
Oops, probably http://db.audioasylum.com/mhtml/m.html?forum=critics&n=88718
Thanks Tedā¦ Yepā¦ that is it!! 
Thanks Ted
That is a funny readā¦
Maybe you should stir things up a bit there too 
Edited to say: I have now read the offending Stereophile review and have problems understanding why the reviewer tested the DACās the way he did as opposed to a simple AB.
Ted Smith saidNo, there are some things we couldnāt do in the DS because of cost: the most obvious one is that Iād like to have used high end Jensen Transformers.
Hi Ted,
Would it be worthwhile to simply replace the existing transformers with these Jensenās now or does replacing a single component require additional fine tuning to take advantage of such an upgrade ?
As you hypothesized, the transformers are a part of output filter and hence the other filter components are adjusted based on the bandwidth of the output transformers. Using quality Jensenās will let more ultrasonic noise thru so the results will be pretty system specific. The better Jensenās wonāt physically fit and using long leads isnāt advisable with the digital signals so close by.
mbauer saidd. Volume knob and source selection knob.
The volume knob should be for an āanalogā volume control.
An analog volume control would degrade the quality of the sound.
Hmm, if the owners of the BHK Pre do agree with that? Or have a look at Auralic. They changed from digital volume control via the Sabre chip in their Vega DAC to a āpassive analog controlā in the Vega G2. The finest volume control I ever had was with my former Lyngdorf TDAI2200 or then with a JR Capri as a pre for the DS DAC. Did their non-digital volume control degrade the sq? Not my impression at all.
There are superb analog volume controls. But the digital volume control in the DirectStream is wholly transparent. This is because attenuation is completely lossless and occurs before the signal becomes analog. It is different from chip based digital attenuation. No analog control has equivalent transparency in a similar application.
Unfortunately, a good number of digital volume controls throw away data and otherwise are poorly implemented. Analog controls can be superior in these applications.
The DSās volume control is ideal in one sense - thereās no level thatās better or worse than any other level and building the DS without a digital volume control wonāt make any difference in sound quality. (Thereās one way this is false: going above 100 with almost full level digital inputs can possibly add a little saturation, i.e. raise THD on some very loud peaks.)
The DS itself has one confounding āfeatureā. It has a fixed noise floor independent of the volume setting. That is, as the volume setting gets lower the relative S/N ratio goes down. So if the DSās output level is well matched to the rest of your system (whether thereās a preamp or not) then using the DSās volume control wonāt affect sound quality - you will be using volumes, say, 60 or 70 to 100 and the noise floor is not an issue.
Each release of the DS has āallowedā high quality, lower volume setting listening by lowering the noise floor and improving clarity, etc. so that the noise floor is cleaner and less intrusive.
I suspect that many (most?) will find listening at a volume of even 10 or 20 will be satisfying in the next release. I wouldnāt claim that that was so with Huron and prior releases.
Thereās one way that the DSās digital volume control could be better than an analog volume control - if the digital volume control could go above 100 and you used that on source material that was recorded at lower levels, it could raise the level (compared to the DSās noise floor) hence improving the resultant whole system noise floor more than would be possible with an analog volume control.
If there were a way to add a very transparent volume control to the DS Iād consider it, but digital boxes are horrible places for traditional analog preamps: thereās gobs of noise both radiated and conducted. A pure analog attenuator (which could be a little less noise sensitive) would mess with the output impedance and wouldnāt be as good on some systems as the direct output of the DS.
Ha! Ted, you just gave a glimpse about a next release. Could you give a little bit more information? Some expected improvements and of course: is there a timeschedule for the next release?
berlin
Time schedule? Not really - so far things are going well, but it takes time.
Tho most people liked Huron better than Torreys, there were a few rough edges in Huron. It turns out that some of the burrs have always been there but they were more apparent in Huron. As we get closer to a real release Iāll explain more. For the next release we know that the sound quality will be better, but, as always, with any changes we need to take care with listening and take care to not introduce other bugs.
And before anyone asks, the next release isnāt going to be adding new features, itās just a few changes in the FPGA and should have all the āgoodnessā of Huron and I donāt expect the overall presentation to be much different. So please donāt start any threads about wishes for the next release, asking to beta, advocating for a fix for your āfavoriteā bug, etc.
I guess I can say what Iām experimenting with to help with clicks and pops:
Iāve spent some time looking at details around transitions on various sources and have found that more sources than I expected stop, change sample rates, have garbage, etc. between tracks or when seeking/cueing within a track. Even sometimes when those sources claim to be playing gaplessly. Also (as some users have reported) on the DS Jr the auto input select would sometimes fill in these gaps with brief snippets of another input that may happen to be playing. Soā¦
Iāve extended the timeout when trying to infer if a source has indeed stopped or briefly paused (for example, if itās just a shorter sequence of 0ās between tracks)
At the input side of the FPGA I look for transitions (clocks starting or stopping, sample rates changing, preemphasis flag changing, going from PCM -> DSD or DSD -> PCM, protocol errors, etc.) and flag each sample as it flows thru the system to mark these changes. Then when a transition happens I start ramping the volume down and toggle the transition flag in the samples. When the changed transition flag reaches the output of the FPGA code I start ramping the volume back up. This allows the system to mute some crap that might happen around a transition. These ramps are fairly fast (approx. 10ms) but they help in a lot.
I experimented with longer ramps but found shorter ramps hide (or at least quiet) the worst clicks/pops and they are less intrusive when unexpectedly present or absent.
I still wonāt claim that all clicks and pops are gone, but more of them are and some of them are now quieter.
Ted Smith saidEach release of the DS has āallowedā high quality, lower volume setting listening by lowering the noise floor and improving clarity, etc. so that the noise floor is cleaner and less intrusive.
Thank you, Ted ā very interesting to know. In the last few months I have felt that my system was sounding better and more transparent than ever. I typically run my BHK pre in the range of 30-45, so the improvement might be due in part to this aspect of Huron. (I expect there are other things involved too.)
When reading some of the above I am a little confused regarding sound degradation from the DS digital volume control.
If my understanding is correct one still lose 1bit for every time the volume is reduced by 6dB, however the clever thing about the DS is that you may lose a lot of bits before you start to compromise the 24bit resolution of the music signal. If you start with e.g. 32 bit you would start losing resolution very early on.