The Sentinel DAC - Design Update #2

[Daniel_Gullman]

Hello all! Good progress has been made on the Sentinel. We have completed a preliminary revised “core” design. This brings us to the second round of prototyping and testing. We will now begin working on the PCB’s and building out these modules. We don’t invest in final designs until we have actual testing and listening feedback. Over committing would compromise our ability to further update and change the designs as needed. Flexibility is key when pushing the limits and looking for unprecedented performance.

What can be seen here is the central power distribution module. This is a multi-layered stack up that takes the incoming DC power from the powerbase and delivers it to both the Right and Left Mono DAC modules and the clock circuitry. You may also notice each mono DAC has been updated from an assembly of parts to individual unibody designs. The original design was made before we had our new 5-axis Grob machining center, so this new design will take full advantage of our new manufacturing abilities.

Looking at the jackpanel, the bottom center through hole represents the incoming DC umbilical linking to the Sentinel Powerbase. On each mono DAC, the rectangular socket will be the dedicated fiber input coming from the Sentinel Digital Director. Above and below the fiber connections are 2 XLR and 2 RCA analog inputs. Closer to the center, we have two XLR outputs per channel. And between those… is an experimental proprietary link for the Sentinel Edition M500’s. More on that coming after testing!

And here is the heart of the system. I won’t say much at this stage, but what you can see is dedicated circuits for both the 44 and 48 (and their multiples) playback. Each crystal is in a removeable ovenized chamber. The clock module is floating on an isolated platform. Using cable isolators, energy in and out of the system is dissipated into heat as the ultra fine fibers rub together. Since the crystal itself is a mechanical part by its nature, we have found measurable improvements by isolating this clock circuitry from unwanted inputs and vibration.

The road ahead is still quite long, but we are having the time of our lives on this one! As always, everything shared here is subject to change. Please stay tuned for future updates as continue our work.

[Henrik_Berg]

Damn what a monster

[Dan]

Hi @Daniel_Gullman

Thanks for this Cool look into the Future!

Dan

[Frank_Lee]

Excellent,I can not wait to see the display of effect drawing of Sentinel DAC.

[AlbertoPilot]

Wow, this is real Tech Porn and I love it!
Jokes aside, thanks for sharing this info with us.
I imagine the 2 XLR inputs could be used for a balanced phono preamp and an external CD player or other source, while the 2 XLR outputs could be used to power the amplifier(s) and a pair of Subs, or to bi-amp the speakers.
Based on this, and with the idea in mind to use the Sentinel as the “control center / main brain” of a digital system, so without the classic analog preamp between the sources and the power amplifier(s), and also with the idea of ​​being able to set up a 2.2 channel system, will it be possible for you to consider in the next version of your M500 also an XLR output to connect another amplifier or a pair of amplifiers? This way the DAC design remains the same, but we could bi-amp (or even try tri-amping in “extreme cases”) the speakers separately and also add a pair of subwoofers which in most cases not only serve to add deeper bass with certain content, but also help to control the response of the speakers in the room.

[Cincy2]

I have to modify my rack to add a third shelf for my Cascade and would like to do this once only. How many separate chassis’ will Sentinal have? Still three? On power base a DAC with two separated channel outputs and then the Digital Director? Thanks Eric

[Daniel_Gullman]

@Cincy2 , The Sentinel will include a DD, Analog Converter, and Powerbase much like the Cascade DAC.

Digital Director: 17.5"x17.5"x4.2"
Analog Converter: 17.5"x17.5"x9"
Powerbase: 17.5"x17.5"x9"

The 2 Sentinel Amplifiers will be the same general size as the M500s.

The foot placement will be different than the Cascade as the overall size is much increased.

Lastly to note, this is all subject to change, but is looking very likely. If you are designing shelving, the only safety check would be to allow for an additional 1" of height depending on the footer design we finalize on. I hope to be able to share some renderings in the next week or two.

[Daniel_Gullman]

Correct, it will be a very versatile system overall. We probably won’t go so fringe as to support tri-amping as we wouldn’t want to compromise the performance for single or bi-amp systems. There is always a balance to be found in designs like this, and I think we have picked a great set of metrics so far.

[Cincy2]

Daniel,

Very helpful. Thank you. I’m glad I asked as my current plan will not work. On to Plan B.

Eric

[AlbertoPilot]

Thank you @Daniel_Gullman ,
What you wrote got perfectly sense.
For bi or tri.amping I was referring to the chance to link or to chain different amplifiers, so if in the new release you’ll put also an XLR out on their input board.
In this way the desing of the DAC I/O board can be the one you shown us.
I understand that a tri-amplification is something interesting for a small niche of hardcoe enthusiast, but maybe a 2.2. set up with bi.amp for the speakrs (M500 for the mid/bass and M20x for the mid/high) with a couple of subs could be the ultimate frontier of the audiophile jurney.
Just guessing of course, I can perfectly understand the difference to run a Company ad be and enthusiast with fantasy
Thanks again for your patience in putting up with my flights of fancy.

[akro]

Sentinel refers to new ultra dac and amplifier!

[AlbertoPilot]

Than you @akro ,

I beg your pardon if I’ve been not clear on my answer.
When I wrote this:

@AlbertoPilot

I was referring to the chance to link or to chain different amplifiers, so if in the new release you’ll put also an XLR out on their input board.

I was clearly referring to the new release of the Sentinel Amps, and in fact I concluded with:

@AlbertoPilot

but maybe a 2.2. set up with bi.amp for the speakrs (M500 for the mid/bass and M20x for the mid/high) with a couple of subs could be the ultimate frontier of the audiophile jurney.

Making reference to how @Daniel_Gullman called the Sentinel M500 in his previous post.
Hope now is more clear and I apologize again if I’ve been misunderstood.

[akro]

@AlbertoPilot

I was clearly referring to the new release of the Sentinel Amps

this is what I am interested in?

as of now, MSB does not have Sentinel amplifiers…thus I thought you were saying that MSB is working on these for future release

[AlbertoPilot]

@akro

this is what I am interested in?

I really don’t know what you are interested in, I was just replying since you mentioned my previous post and I was wondering if it was the case to clarify what I wrote since It’s my philosophy to think that if someone has some doubts about what I wrote or said, its my fault and so I need to clarify better.

@akro

MSB does not have Sentinel amplifiers…thus I thought you were saying that MSB is working on these for future release

Correct. I just had this idea upon @Daniel_Gullman words on this thread:

@Daniel_Gullman

And between those… is an experimental proprietary link for the Sentinel Edition M500’s. More on that coming after testing!

And that’s why I’m kindly ask/suggest if in this Sentinel Edition amps it will be possible (or not, maybe the design is already fialized) to add also an XLR OUT on the imput board, so it will be possile to connect in chain another amp or a powered subwoofer.

Hope that now this is more clear and sorry again if my previous message wasn’t.

[Erik]

I am very excited about the new Sentinel DAC and appreciate you sharing information on its development.
Have you considered using a copper chassis to enhance the sound quality?
Additionally, you mentioned the Sentinel Amps. Will my M500s be upgradable to the Sentinel Amps, or will the Sentinel Amps be a new top model positioned above the M500s?

[Daniel_Gullman]

@Erik , things are still quite fluid with the design. In regards to the amplifiers, we were originally going to keep them very similar to the M500’s but are now exploring more options to improve the performance. Until we have more details hammered out, I can’t promise anything in regards to the upgrade path, but my plan is to have something in place. I know there was an original discussion of just upgrading the current input gain stage, I do not think that will be the case moving forward.

And, with the new look of the Sentinel, the current M500 simply wouldn’t cut it

[Daniel_Gullman]

@akro

MSB does not have Sentinel amplifiers…thus I thought you were saying that MSB is working on these for future release

Nothing is nailed down just yet, but it does look like we will be adding Sentinel Amplifiers to the lineup. Only if the performance we achieve warrants it of course. I thin the confusion can come from us to referring to the Sentinel amplifiers as modified M500’s, but the two models are now looking very distinct moving forward. Excited to share news soon.

[Ron]

Dear Daniel and team,

Thank you for sharing al these wonderful details on the road towards the Sentinel DAC; truly inspiring.

I have a question I hope you can shed some light on:
Are there any plans to incorporate room correction in the Sentinel DAC and, if so, what form will they then most likely take?

The reason I ask is, that, as all components in the playback chain are progressing, the one thing that remains constant is the listening room. As the weakest link determines the overall quality of the playback, the room imperfections will become ever more prevalent.

Of course, considering the pricing range of a beast such as the Sentinel DAC, it is fair to (also) consider physical treatment of the acoustics of the room, as that is likely a cheaper option. Still, money aside, it will not always be possible/practical to make major changes to the listening room and, as such, it will still be interesting to hear your opinion on this.

Kind regards,
Ron

[Dan]

I kind’a feel strongly about this. I don’t want the Cascade, or any DAC, doing room correction for a stereo system.

The Cascade is clean, noise free, clear, and evokes a strong positive response from everyone who comes over to my house to listen to it. I know I went out on a limb buying it without ever having listened to it, but it is doing everything that MSB said it would and more. Everything I was told about how it was totally focused on accurately producing an analog signal from the source bits of a digital file was true. I’m ecstatic I purchased it.

Please ignore the following rant of a crazed Cascade fan unless you want to know why I feel this way.

So, I don’t want any additional processing done to the bits in a digital stream. I don’t even want the electronics required to do room correction in my DAC. I just want the DAC to convert the bits from the digital file to an analog signal as accurately as possible, and do nothing else.

I think it is better to either directly “fix” the room (via absorption and/or dispersion) or do digital processing to a source stream outside the DAC. For example, Roon, with the help of software like Room EQ Wizard, can do room correction with its Muse DSP. Also, HQ Player can be used to do room correction outside the DAC.

Any kind of digital room correction adds noise and distortion to a signal simply because it adds additional processing to the digital stream. Every digital arithmetic operation that tries to emulate real numbers adds a small amount of error to what it produces. That’s why seemingly innocuous code like:

a=1/7
Print 7 * a
can sometimes end up producing:

0.999999946

There are techniques that will minimize these errors. That’s why environments that require precise numeric processing will use software like Matlab, Mathematica, or Maple. These companies have spent decades refining their products to produce precise numeric results.

Adding the processing power to the Sentinel to do HiFi room correction could double the amount of electronics in the Sentinel. For example:

Using HQ Player to do room correction could end up requiring a standalone, big chassis, computer to do the processing (in real time) for room correction. I don’t use HQ Player, but I know several people who do and some of them have large, high-performance processors (sitting in another room because of noise) to run the filters they like to use. If the cut back on processing power, HQ Player can’t keep up. This is a pretty good indicator of how much extra processing power would need to be added to a DAC to do High-Fidelity room correction.

Maybe the Sentinel could just embed a few Nvidia RTX 4090s to handle the work load… then it could mine Bitcoin when it is not playing music… just kidding, of course.

I do use Roon, but I don’t use this feature. I suppose I should experiment with it to see whether it helps or not… maybe someday I will get around to that.

I know some people who use NOS (non-oversampling) DACs simply because they want to do the over-sampling and filtering outside of the DAC (with HQ Player) and don’t want the DAC doing anything else to the bits.

I do use room correction too, but it is on my AVP for surround sound; I don’t consider that HiFi, though the audio it produces is very good. For sure, my AVP does not have the processing power of a high-performance computer, but it is “only” processing movie surround sound.

I could rant on other reasons why I think room corrections inside of a DAC is a bad idea, but I’ll stop now.

All these things together are why I want my DAC to just be a DAC.

Of course, your mileage may vary.

Dan

[Ron]

Dear Dan,

Thank you very much for your passionate and detailed response.

It is good to hear the opinions of MSB’s customers as well.

Let me give a bit of background information where my question stems from:

The heart of my current system consists of the Lyngdorf TDAI 3400, which is an integrated DAC + amplifier that includes room correction as well.

Obviously, the TDAI 3400 is quite a few rungs down from any and all of MSB’s DACs, especially your Cascade, let alone the upcoming Sentinel. So, as you rightly pointed out, YMMV. Having said that, I experience a big uptick in sound quality in my system when activating the room correction hardware of my DAC: tighter bass, more micro details and an increased soundstage.

Based on my very positive experience with the room correction I’m having in my humble system, I was wondering how far the sound quality envelope can be pushed with a top tier DAC like the Sentinel when incorporating room correction and hence my question to the staff at MSB.

Kind regards,
Ron