After Yale...

@Ted: Can you please share some of your programming activities for the next major version of the DirectStream firmware? It would very interesting to know what aspects you are focussing on regarding e.g. noise and jitter reduction,

I would very much like the DS to have a little more 'richer' sound and with a little more slam and attack with DSD recordings.

I guess most of my ramblings about new releases are buried deep in other threads.

Some of the improvements from Pike’s Peak to Yale were directly driven by feedback about the change between Pike’s Peak and 1.2.1 - I knew exactly which changes were explicitly made and could correlate them with most of the feedback. Over the same time period I found some ways of better controlling noise and jitter in the FPGA. Doing the first steps of that jitter/noise related work facilitated combining the best of 1.2.1 and Pike’ Peak. So I knew that the next release (Yale) would be better in some technical ways and I hoped that the jitter/noise work would also be evident.

The FPGA code roughly comprises misc control (e.g. talking to the display processor), digital input decoding/processing, PCM upsampling to 176.4k or 192k, upsampling DSD and PCM to 28.224MHz and the then down converting to single bit at 5.6448MHz with a Sigma Delta Modulator. The misc. control and initial PCM upsampling work are both relatively simple compared to the final big upsampler and sigma delta processing so I first worked on those simpler parts of the FPGA code to avoid wasting a lot of time if I was barking up the wrong tree. Yale showed that the noise/jitter work was productive and on the right track.

The next release of the DirectStream OS will certainly continue the jitter/noise reduction work by containing a reworking of the final 28.224MHz upsampler and a similar reworking of the sigma delta modulator. Until it’s done we won’t really know how big of difference in sound quality it will be, but it should be noticeable.

As in Yale, once again that work will enable some further refinements of the overall design. In particular it will allow the incorporation of some ideas I had last summer. One of them should lower the low level low frequency distortion continuing some of the work for the 1.2.1 release. The other should lower some jitter induced noise across the board. These two new work items should each also allow a measureable decrease in the ultrasonic noise which will be noticeable in some (most?) systems. I expect that their effects will somewhat overlap so I’m not making any specific predictions for the final measurable reduction in HF noise.

There are also a few bugs that need fixing and tho Yale makes most DS customers happy, there are a few who prefer an older release and I’d like to learn from that as well. I know that no software release will be a step forward for all customers and I’m pleased at the general reception that Yale got, but I can still try to do better and please more customers.

Some of the expected changes in sound quality with the new software will echo some of the changes from 1.2.1 and Pike’s Peak to Yale: A blacker background with less noise and jitter will add more definition/separation of the instruments/voices and deliver more detail without being analytical. Less jitter always seems to add bass definition and also a more accurate portrayal of the performance’s/recording’s timing.

Not picking on anyone and just trying to be honest, given the architecture of the DS I don’t completely understand how one would make changes to DSD sound production without making the same changes for PCM inputs. I.e., I think the differences that people report for DSD vs. PCM presentation in the DS are actually differences in the recordings, not a reflection of either inherent PCM vs. DSD differences nor any particular features of the DS. For example the recordings that I have that were mastered for DVD-A have a different sound character than the recordings that were mastered for SACD. The DVD-A recordings in general have stronger bass, more drive and slam. But I have no reason to believe that those differences comes from being distributed on a DVD-A vs. being delivered on an SACD. I think it reflects the styles of the recording and mastering engineers involved - they pick the editing and delivery system that best reflects their taste/style/preferences/preconceptions/etc. and this becomes a self perpetuating paradigm. (Don’t get me wrong, I do think there are some significant technical and sound quality differences between PCM and DSD, but anything you think is a feature of the DS’s PCM is obviously possible in DSD.)

In an ideal world the DS is getting better at being faithful to the recording, without being brutal about it. That’s a hard edge to walk but so far I believe I’ve done it by being as technically correct as I can be at each point in time and I have to believe that this is also the correct path for the future.

Thanks Ted, this makes me want more PSA.

As always, great info Ted.

Excellent, excellent post, Ted!


Ted, your dedication to your customers (and, let’s face it, fans) is amazing. And greatly appreciated.

We need Ted merch.

It’s funny, Ted and I don’t talk enough–and I too learn what’s going on through his posts. Bravo! And thanks for sharing. It’s exciting.77_gifinlove_gif

Elk said We need Ted merch.

Hi Ted and the PS Audio staff,

Any (rough) idea when the next OS after Yale will be released?



Focal_Point, in the “Yale Final - Impressions” thread, Ted said the following in post 335 (the last one as of this writing):

Ted Smith said
People are asking me to slow down (especially print magazines like Stereophile, TAS and HiFi+) We’ve been two releases ahead of published reviews in the past. Also plenty of people on this site have said the same.

I’ve been busy with a few other projects (don’t ask, you’ll hear about them in due time if they work well) but I expect to get back to working on the next software release November to December (or possibly January). The work is a little harder than the last couple of releases so it’ll take a while. Also we need to coordinate the release with other PS Audio releases. So I’d guess not earlier than next Feb or March.

Hopefully that answers your question.

@ted: Any news from the planning of the development of the DirectStream firmware. Will it be out in the beginning of 2016?


If by beginning you mean Jan or Feb, then no. March? maybe, June probably.

I am really happy with the present firmware

adding a little tube preamp adds the weight I want. If I go back in firmwares I can tell how much hard work TED and company have put into making this dsc better with each release

going forward from 121 it’s going in the direction I needed and by Yale it’s pretty damn good

if TED can further implement an even better sound that would be somethings really special

thanks for your work TED

I continue to be amazed and impressed! No other DAC is this much fun! The upgrades are always something to look forward to…beer_gif Ted merch…not a bad idea

In the meantime I have such an extraordinary transparent, holographic and smooth, natural sound and the level is so high, that I’m just happy with what I hear and I take it as a great luxury, when a further improved firmware comes some time.

I think we should keep calm with constant update requests every few months after the last one, as this could be one of the reasons, not more manufacturers offer that.

For my part, I’m just browsing/exploring through my music at a so much higher level and althought having about 300 Hires albums of which 100 are DSD, my initial impression confirmed, that mainly recording quality and mastering matters, as many CD’s sound better than some hires files and the CD sound quality achieved by the DS really is nearly the same as hires, that’s crazy. I never thought I will hear that quality from a digital source. And I love that whole money saving concept with just a DAC and bridge and files instead of data storage media. Ted rules. And Paul. And Dennis (the Bridge maker?)

+1. Thanks, jazznut, for giving us this appreciation of the DS. I feel the same. Let’s give Ted a break and enjoy what we have. In the US we just had the annual Thanksgiving holiday and I was thinking that the quality of music reproduction that I get at home now – of which the DS is a very significant part – is truly something to be grateful for.

Ted Smith said If by beginning you mean Jan or Feb, then no. March? maybe, June probably.

Ted, please, let the new firmware will be released in March.

A year from Yale this so much...

I have the software written and compiling well. I’m still debugging it and that’s a process that may finish today or in a few weeks depending… After that we need to listen critically to see if it indeed sounds like I think it will of if we have to do some serious tweaking. Then PS Audio needs to work it into a release schedule.

I do like the way the new software is coming out. Some of the code I rewrote was written quite a long time ago and I’ve learned stuff in the mean time but you always do better the 2nd (or 3rd, etc.) time you rewrite things - I’m getting more done with fewer FPGA resources and the code is simpler.

Simpler always takes the most time and effort.

Sounds like you are making excellent progress. :slight_smile: