AC Filtering, Grounding Boxes, Linear PSU and Balanced Power.

[YashN]

6 hours ago, marce said:

It shows nicely how bad lap tops are for noise

 

Again though, one would have thought that the DAC input should have filtering on the supply if it is designed to be USB powered.

 

It wasn't a laptop, it was from a 2009 24" Core 2 Duo iMac running Mavericks.

 

This said, ifthe laptop is battery-powered rather than having the power cord connected, there could be a possibility that there is less 'noise'. Problem: my 2009 MBP runs El Capitan and that old M-Audio card doesn't even run on newer OS, so I haven't been able to capture that one.

 

Now, about DACs 'should have filtering': this is happening, the newer designs do have them. I was supposed to review one of the new DACs but unfortunately couldn't because of being taken up.

 

You expect things - but that means nothing in reality. Reality and your assumptions must be tested in real life. Most people aren't even thinking about this as an issue at all despite some people warning about grounding issues, leakage currents and so on.

 

How many people actually sit down to dissect a generic USB cable and see how it's made inside, vary the geometry and listen, verify how the shielding configuration is, test all combinations at the shielding / connector interface and listen and try to make sense of it.

 

Not many. Most people have a model inside their heads that goes like this: 'It's digital, as long as the bits arrive at the other end, the sound shouldn't change, why don't you capture the DAC outputs and show us.' 

[YashN]

6 hours ago, sandyk said:

 

Marc

 Give it a few days, and for quite a few members it will be back exactly the way it was. : You don't need better USB cables, you don't need USB widgets, you don't need low noise Linear PSUs etc., AND if there IS a problem, it is due to poor design of the USB input of the DAC !

 Are you so naïve to believe that a single post like this will change those members minds ?

All that matters according to some, is that the 1s and 0s leaving the USB port are correct.

 

Marce isn't totally guilt-free in this respect 

[YashN]

A few other things I would have liked to do at the time I made the captures:

 

Since the custom USB connector  - by that time I couldn't even call it a USB 'cable' anymore, as there were components in a circuit computer-side as well as along the GND line - isolated the DAC quite a lot, and this was even enhanced by a custom shielding configuration - I started to think about what I was doing at the capture side.

 

The M-Audio can  be powered two ways: by its own external PSU or by USB (the same very noisy computer USB supply from the same iMac - oh no!).

 

So here, I chose not to use the USB power from the iMac through the M-Audio USB cable, but to power the soundcard by its external power supply.

 

However, this doesn't guarantee me that whatever noise is being transmitted via a generic USB cable from the Computer still doens't affect the card itself and therefore the measurements.

 

I could only assume (and here for lack of time and better equipment) that since the M-Audio is a card used for music composition, so also for capturing Microphones and other instruments ar 24-bit 96kHz max, that the manufacturer did some work for the isolation (its an older USB implementation so doesn't require the more recent and previously inexistent USB 2+ galvanic isolation implementations).

 

Secondly, the M-Audio external power supply I used was also not a Linear one...

 

To make things better for measurements, I would have liked to:

 

1. Have a clone of my Custom USB Connector to use that too for the M-Audio

 

2. Ideally power the M-Audio by an external, low-noise battery or something like that

 

 

Additionally, a few things to notice:

 

- I specifically did not work directly on isolating the data lines. However, filtering computer-side still improves SQ.

 

- The filtering computer-side still works when I A/B it (I installed a switch and a LED) even after I set up a custom shielding configuration for the USB Connector (which by itself already increased SQ too)

 

What this seems to suggest is that the data lines are still affected by whatever is happening computer-side, although I am very deliberately not powering from the computer, and although I also further isolated by working on the shielding configuration.

 

And finally this:

 

At this point in time, I thought I had a really good setup and that any leakage currents were not passing through my custom USB Connector, so I was thinking that if I re-connected my AC Filter in the system, it wouldn't make a big difference.

 

Here again, big difference!

 

This is what allowed me to say last year that I have a long-term plan of avoiding SMPSes in the listening setup: the work needed to really filter out all the nasties with SMPSes is extensive: you need to ensure the interconnects do not propagate unwanted things, you need filters post-SMPS as well as filters AC-side.

[YashN]

13 hours ago, gstew said:

And very nice pix and process. Thanks for sharing!

 

Greg in Mississippi

 

Wish I had taken some more pictures and captures before and after a layout change.

 

Here again, 'just a layout change' right? That means just changing where the capacitor returns pre-regulator went (the overall schematics and circuit did not change).

 

Huge SQ difference.

 

What this showed me is that even at that micro level, loop areas, connections, resulting EMI/RFI, returns/'grounding' can have large effects.

 

You can have 3 different PCBs with slightly different layouts, from the same schematics giving you vastly different results.

[YashN]

Relevant: SMPS and Grounding

 

A portion of leakage currents of SMPSes can be shunted by that technique.

 

If I'm not mistaken, this is similar to what the Tripoint 'grounding' boxes are doing (albeit with some additional passive filtering and other things) because the box is indeed connected to Earth too (as opposed to the early Entreq boxes which specifically only do what they term 'signal grounding' with an external box, some additional material and no connection to Earth).

 

So I think John found the explanation of that the Tripoint does: it is shunting part of Leakage Currents to ground, allowing this diversion not to affect system SQ as much.

[YashN]

52 minutes ago, YashN said:

 

[YashN]

On 12/30/2017 at 5:37 PM, sandyk said:

 

Well done !!! 

I can relate very closely to much of what you have done here.

 

Thanks. And by the way, your existing posts on the forum about a couple of setups to try for the DAC when trying to power externally came in handy, as did some of our PMs.

 

I am not sure why my DAC sometimes work without one of the (technically filtered) power connetions to the computer as it seems it didn't at all initially, but it now does. I suppose it could be because of the onboard battery going low sometimes.

 

On 12/30/2017 at 5:37 PM, sandyk said:

Unfortunately, the closed minded Objective set will ignore your evidence and continue on their merry way claiming there is nothing wrong with normal USB implementation and keep dishing out their flawed advice.

 

Up to them . I've found I don't get big results fast if I spend time trying to convince others. I do if I focus on my setup and my research and spend time conversing with like-minded people.   Then I can listen to the fruits of my (and like-minded people's) labour while building something else.

 

On 12/30/2017 at 5:37 PM, sandyk said:

Perhaps you can put this post in a blog for easy reference by others ?

 

Maybe, but a Bookmark can work too. I could paste the contents in my Blog here probably.

 

On 12/30/2017 at 5:37 PM, sandyk said:

Also, it deserves posting in a more friendly area of the Forum such as the Uptone area where members trying to sort out these problems can more readily locate this information.

 

The problem with that is it becomes an area managed by Uptone. I do like 'Superbad' Alex and John, of course, but doing that we come under an extra layer of 'management'.

[YashN]

On 12/31/2017 at 1:44 PM, Cornan said:

 

Spot on! My conclution exactly (as I've posted on another thread). I connect my JSGT to Entreq grounding box which actually sounds better than connected to the same star-earth wired PSD as my floating SMPS in my setup (floating SMPS is connected to a balanced IT with floating secondary).

 

Let me know which Entreq box you have as there are several, and they do different things. The original Entreq box considered in this thread and the original post was solely focused on 'signal grounding' and had some odd properties, like the SQ effect taking some time to be heard  - this only from third-parties recounting it as I haven't heard and Entreq in a system. I did build and use a rudimentary 'signal grounding' contraption at one time and still heard an improvement in SQ in my setup despite the AC Filter already being used.

 

As for me: Having experimented with SMPSes, my DIY Linear PSU + my custom USB Connector + my DIY AC Filter, I have heard how the SMPSes affect SQ in several ways.

 

That's why ultimately, I just want to get rid of all of them in the listening room if I can and go all Linear or some other clean form of powering.

 

Quote

 

 

[YashN]

On 12/31/2017 at 3:22 PM, gstew said:

 

YashN,

 

All of this sounds good. AND should be  a good set of guidelines and areas of inquiry for those looking to optimize their audio setup.

 

Hey Greg, thanks man. hope you had a great N.Y. party, all the best for 2018.

 

Anyone with better gear can probably easily do better measurements. It's just a matter of taking the time.

 

Quote

 

AND to me one of the most important points is starting with really low-noise power supplies, at their output, on how much noise they feed into the AC line, and how they react with other gear (John Swenson's high-impedance SMPS leakage). 

 

Totally agree. My DIY Linear PSU combines a few clever things, and a good part of those actually come from some descriptions from John, at least prior to the Regulator.

 

For post-regulator, I had the opportunity of directly experimenting with and hearing what capacitors do at the output section. Things like why people were saying great things about Vishay and Elna capacitors. I also had the idea of testing a capacitor used in one of my old digital cameras for the Flash. It does wonders for attack reproduction.

 

Now, however, before one gets too excited about capacitors, one has to really think about what we're doing when building an LPS with an old regulator like the LM317 which is what I did as an experiment in building my first DIY Linear PSU:

 

- It's quite a flawed regulator, you can get better nowadays, but it's cheap

 

- A lot of its flaws have been analysed, so if you look for them, you can find information about how to work around these

 

- Internally, there's a lot of components in it

 

- What you're really doing with the post-Reg components is battling non-linearities of the LM317-based circuit, while making instaneous current delivery, power transfer, impedance response + symmetry, ripple-minimisation, etc... satisfactory for audiophile use.

 

Overall, it's not very good, but it's a good basis for learning, because if you actually take some time to build circuits with it, listen (or measure/graph or listen + measure/graph), simulate, revise, tame its flaws, then you'll learn a ton on circuit-building for power supplies.

 

I could do much better using it nowadays, but it's far better to use newer regulators IMO.

 

What I gained from doing this though is doing circuit design while simultaneously listening in an audiophile setup.

 

This is *priceless*, and very different from learning circuits from books.

 

Quote

 

One of my guiding principals has been to eliminate sources of noise rather then try to filter or shield from them. My thought is that once you have a particular noise source, filtering or shielding will only reduce its impacts, not eliminate it. The best way to have low noise is to not create or introduce it in the first place.

 

Agree with that, if it simplifies things a lot.

 

Quote

 

So your long-term plan of avoiding SMPSs in my setup is something I've worked hard to achieve... and with just recently moving to amplifiers that don't use SMPSs, I've gotten there. It was good. AND well worth the effort and expense to get there.

 

 

 

Definitely, I remember seeing your custom Linear PSU for your computer. Way to go!

[YashN]

On 12/31/2017 at 4:40 PM, sandyk said:

 

 No, but he appears to be far more open minded than most though.

We need people like Marc to use their vast experience to help further improve this area.

 

I'll PM you sometime about that.

[YashN]

On 12/31/2017 at 4:51 PM, Cornan said:

+1 @marce is a great guy with a lot of knowledge and an open mind to unexplained things.@sandyk

 

 

Yet, you wouldn't let someone who is an expert solely at cooking manage your family's capital, correct?

 

Audiophilia is its own Knowledge Domain.

[YashN]

13 hours ago, jabbr said:

Yet I am confident that electrons are electrons ?

 

Said another way, there remains a great deal that we can still do to optimize audio circuits which falls within Maxwell defined behavior. Once that’s done we might at that point consider whether or not extra-Maxwellian behaviors are relevant to audio (at this point there is zero suggestion) ... well of course unless you want to consider Freudian behaviors but I think audiophile marketing has that covered quite nicely, so I’ll stick with physics when ? ng about it, and also listen to what I like ?

 

Despite all that you wrote:

 

I still wouldn't let you manage my Capital, i.e. not unless you showed you have expertise in that.

 

Domain Knowledge is important. It is important you consider Computer Audiophilia as its own domain.

[YashN]

7 hours ago, Cornan said:

However, there is still many out here worth listening to and to gain great knowledge from. @marce is one of them on my list.

 

I'd rather he stops visiting my threads and also stopped being mentioned in my threads.

 

Since you only recently made an account over at DIY Audio, I suggest you look at some of the trollish posts he has made over the years over there... Not even sure what brings him here at CA...

[YashN]

1 hour ago, mourip said:

I find CA to be one of the few forums where real progress is being made by a few users thinking outside the box. Some of the progress is made and validated by hard science but a lot of it starts with members who use their ears to notice a positive change and then do experimenting to figure out how it is happening. This is one of the most open minded threads on CA or anywhere really. It is refreshing to find a place where anything can be considered without rejecting it out of hand just because it does not yet fit into ones own well studied understanding.

 

Outside this thread on CA there are definitely nasty criticisms from members who are anything but non-existent. There is a small group of folks who can always be counted on to criticize ideas that are real but just not fully understood. Some of this criticism is very direct and intentional, some is thinly veiled as humor or thread diversion.

 

Lets please leave this thread as one of the few where anything can be considered and critical evaluation remains helpful.

 

Thanks for the cool post. If you reach back to the start of this thread, and some of the few I made, you will see that there were quite obvious attempts to derail it as well.

 

There are many threads where cool things are happening - Cornan and Austinpop are newer members who have contributed a lot from what I can see. John Swenson and others have been there for a longer time, etc...

[YashN]

6 minutes ago, marce said:

I also have as much right as you to be on here, this is a bit beyond the joke, playing god and saying where I should or should not go, pathetic just because we disagree.

 

My threads, my rules.

 

You're not welcome on any of my threads.

 

Let's leave it at that.

[YashN]

14 minutes ago, Cornan said:

 

I understand. It is good to have a better record of course. I have´nt seen him around on DiyAudio just yet, but as you said I am all fresh there and I am only following like three threads over there so far. 

 

 

There is a lot of good information and good people over there at D.A.

 

However, be aware of certain policies in place there where your posts can be removed without warning and that you cannot say anything about mod abuse over there.

 

If you dig, there is a lot to learn, including about the 'venerable' as a rather unsavoury character over there described it LM317...

 

There is a lot of great information about circuit-building which can be generally useful.

[YashN]

8 hours ago, Cornan said:

 

I am using Entreq Minimus basic version (copper - not silver) in three spots right now. JSGT on Aqvox switch-8, GND screw on Aqvox switch-8 and JSGT on TP-Link Vivid powerbank (charger). My Aucharm grounding box takes care of the JSGT on my main router (powered by a floating LPSU and still makes a difference for the better). Entreq is considerable better than Aucharm.

 

What you might not know is that all of my SMPS is floating and have LT3045 linear voltage regs in series. My setup is probably more floating most people using SMPS or LPSU. Anyway, JSGT nor Entreq improve everywhere in my setup. If I for example add a JSGT to my DAC, streamer or BluWave the SQ gets worse.

 

The main thing that I have noticed in my setup is how both isolations/floats improves in series. I have said it before and it still holds true that no isolation is absolute. I strive to float my intire setup from the outside world and isolate everything inside my setup from each other as much as possible.

 

Interesting setup.

 

I will have to do some experiments with the SMPSes here, but as I've said: my previous experiments already showed me they affect gear in more than one way, at least two ways, if not more: I need both the AC Filter and the Custom USB Connector to minimise their effects, so that's a lot of additional gear to have to put in place.

[YashN]

On 2/12/2018 at 10:47 AM, jabbr said:

 

I’m not offering!

 

I know! It was also just an example. I also know that if you, jabbr, put your mind to it, you'd be successful at it, so then, I wouldn't mind if you were offering.

 

Quote

... well unless you need help saving $$$ on a so-called grounding box ???

 

I'm pretty well-served here as this is what I did:

- I spent a lot of time dissecting the posts by people who actually bought one of the Entreq boxes, and one of the Tripoint boxes on WBF.

 

- I spent time researching, studying, building, testing, setting up critical listening sessions where 1 (me) or 2 persons could listen and discuss their findings.

 

- I built a really, really rudimentary 'signal grounding' apparatus to just quickly invalidate it... well, it wasn't invalidated at all. I was suprised

 

- I built my own AC Filter box

 

- I built my own Custom USB Connector

 

- I built my own very Low-Noise Linear Regulated PSU for the DAC. Since then, I also built a Dual-Rail one for a Modular Synthesizer, using the same technologies

 

So now, since I used various combinations thereof in my system, I know precisely what the so-called 'signal grounding' box does, at least part of it. There's another part which is intriguing, but which I haven't experienced.

 

If anyone has been paying attention, @JohnSwenson , on another thread has shown a simple method to reduce the noisy effects of an SMPS on your setup... If you compare this method with my rudimentary 'signal grounding' and what the Entreq box does, it amounts to a similar thing.

 

This is why I was asking early in the thread whether just linking the chassis of the gear would solve those problems of noisy currents. Speedskater thought that would be the case. In my setup, I found it wasn't enough.

 

Despite also integrating my AC FIlter box (so Chassis interlink + AC Filter Box), that external 'grounding' (I think 'external reference' here would be a better term) still made a difference in sound.

 

This device wasn't expensive to do at all since my only goal here was to rapidly invalidate it: make the simplest form of it I can think of, connect it, listen, and discard the thing as I thought it wouldn't have any effect. Well, we know what happened there. The device as described a couple of times before in this thread is simply this:

 

- a copper tube that I found for cheap at a hardware store here

- the shield from a cheap satellite cable that I found there as well, and flattened

 

That's barely CAD3, maybe $2 max.

 

The point is that I actually tested the thing a while ago in my setup rather than just contemplate in my mind why for theoretical reasons 'this shouldn't work' as so many have been prone to do.

 

The first time I did this I was already flabbergasted: I had built my own power cable based on a Chris VenHaus design. Didn't expect anything at all: after all it's power, just plug it in, right?

 

 

Quote

I’d say take information, and others opinions for what they are worth. I do see a tendency in Audiophilia for folks to latch on to firmly held beliefs without really questioning the basis for these beliefs. 

 

Ideally rational discourse would help  folks question their entrenched (Entreqed???) beliefs, and learn ... 

 

Reasonable opinions, and experiences, are always a value to me, and in my experience, cross-fertilizing domains is a huge way forward

 

If you were trained in Science and Engineering, you take the information, you test it out or try to invalidate it. If you invalidate it, then there's no need to spend more time on it.

 

On the other hand, if you don't invalidate it, then this becomes an interesting pursuit to do further investigations on.

 

At least that's what I do. I learnt a lot doing that and I never viewed Science as a static corpus of knowledge

[YashN]

On 2/12/2018 at 3:23 PM, Ralf11 said:

Is Computer Audiophilia its own domain, distinct from say digital or analog electronics?

 

It's both, but most of the issues are issues related to the interference one has on another. It really is, overall, an electrical problem. And that's why understanding the System itself is what makes you progress on this path.

 

Additionally, there is 'analogue' hidden in what we call 'digital'. This a big source of the issues.

 

Digital people aren't too concerned with the EMI/RFI for audiophile purposes that their digital circuits make: they mostly design to pass a threshold of acceptance which is far less demanding that what audiophilia field requires.

 

and BTW, I always thought it was "my server, my rules"

 

The real question here is: why didn't you think this was already a given?

 

I think you've been around this forum a while, no? You mean you haven't seen people in their threads asking Chris to purge their threads of some drivel? The OP has this leeway provided and acted upon by Chris himself.

[YashN]

On 3/2/2018 at 3:42 PM, Speedskater said:

How does an Original Poster get to set the rules about whether corrections and engineering facts get posted or not?

 

You make no sense at all, so I have no idea what you're talking about.

 

If you have proper engineering facts, do post them. There are a handful of questions I have asked you which you haven't replied to earlier in this thread.

 

Also, if you are the one who wants to post 'corrections and engineering facts', by all means, do so, as I did appreciate you taking the time listing a lot of interesting resources, namely books.

 

However, you also made a mistake about how the return paths work, for which I had to correct you about. Maybe that's why you're bitter about something?

 

If you're so bent on quoting your book knowledge, make sure you quote it properly.

 

If you're talking about marce supposedly offering corrections or engineering facts, well that's entertainment to me because all he did a few posts back if something like 'I thought USB would work like this' or whatever (it's unimportant - he hasn't done the work, he doesn't know but if you really want to know what he posted, just scroll back).

 

[YashN]

On 3/2/2018 at 6:58 PM, sandyk said:

A correction is one thing, but "engineering facts"   may not always be " facts" despite being sincerely believed by some members.

Many Textbooks get periodically updated too, as more recent research shows the need for updating. 

This applies in all areas.

 

Absolutely, these fields are dynamic, not static, as people perfect heir knowledge and their models of the domains they are investigating.

 

Totally agree with you, Alex.

[YashN]

On 4/3/2018 at 7:51 PM, sandyk said:

 Using an AC filter box in line with some components may even degrade the sound.

I tried fitting a typical commercially available filter like the attached , in line with a Linear +5V USB PSU's AC Input and it made it sound worse.

https://www.ebay.com/itm/1PCS-EMI-RFI-Filter-AC-250V-10A-CW1D-10A-T-Suppressor-Power-Line-Noise-Filter-/152254296992

 

There can be a lot of different implementations here. Mine has been iterated upon quite a lot and always makes a positive difference, be it on audio or on video.

 

In fact, I recently removed it and despite all the other filtering and customisation/isolation between the computer and the external USB DAC, the holographic, detailed, 'they-are-here' effect is gone.

 

The system still sounds good, but I know it's several levels below its potential.

[YashN]

On 3/31/2018 at 3:26 PM, Speedskater said:

When 'marce' posts engineering facts, I would put money on them being correct. He as been posting in engineering treads of audio forums for over a decade. Digital circuitry is his day job and he knows of what he speaks.

 

You'd lose a lot of money, unfortunately.

 

Knowing Digital circuitry doesn't make one an automatic expert in analogue circuits.

 

Computer Audiophillia is about Mixed signal circuits and EMC. The issues we get are almost always where assumptions about Digital and Analogue are wrongly adopted or when the Digital viewpoint of robustness of transmission doesn't take into account any intermediate D/A and all the analogue issues that can accompany transmission in the analogue domain.

 

By now, attentive people reading here should know more about both USB and any intermediate A/D and D/A steps from reading a file on an HDD or elsewhere through to the DAC then onto Speakers. There are many such steps, each can be damaging to sound.

 

All we get from this supposed 'expert' still polluting this thread is how he thinks things should work.

 

Better stick to digital if that's all he knows about.

 

[YashN]

On 4/1/2018 at 2:27 PM, jabbr said:

 

Very good start.

What I would like to see are some good measurements.

 

I did recording captures at the DAC output, using a pure Sine generated by Audacity using the M-Audio Fast Track Pro as capture interface, then did FFT on the results. Maybe you missed those? That's in and for my system. Not ideal for sure (I did mention caveats in my post).

 

For good measurements, go ahead and do the same in your own system. I am fairly sure you have better measuring gear than I do.

 

 

Quote

 

Normally I'd say listening is fine and listen to what you like HOWEVER in the case of grounding boxes which have no rational explanation based in what physics of electromagnetism we understand, if the claim so goes against traditional electronics I ask for real measurements to support a difference. 

 

I disagree with your perception of 'no rational explanation': from what I gather it is the same phenomenon by which grounding works within a system, apart from the intriguing thing that some people mention with Entreq, i.e. it takes some time for the effect to come on. I haven't experienced this in my system: the external 'grounding' effect occurs immediately.

 

So for my own experiments: I see nothing other than the simple contraption allowing dirty currents away from areas where they were previously wreaking sonic havoc.

 

It's nothing more than improving returns IMO, so no exotic or new physics is needed here (apart from that thing above).

 

What's not needed though is the bookish statism and inherent misconclusions ("this shouldn't make a difference, therefore this doesn't work").

 

 

Quote

 

Our ability to measure electrical phenomena goes way above our ability to listen, not that we always know what we are measuring but for example, if there is less noise on the ground plane then that is measurable. 
 

 

@PeterST has done a lot of measurements exactly like that, especially at the computer-side planes IIRC.

 

As for me, I have nowhere near the gear I'd like to do extensive and more precise measurements but you probably do, don't you? So the captures and FFT are what they are.

 

 

Quote

If you are trained in science and engineering once your listening test detects a difference, you validate this with measurements. You can't publish a physics paper without either theory and/or measurements.

 

I agree.

 

However, I am not publishing any paper here.

 

Quote

No one does, but extraordinary claims require extraordinary validation. Listening tests do not alone validate nor invalidate physics claims -- perhaps psychology.

 

Try it for yourself like in a build, listen, and make your own conclusions and measurements.

 

You may not have any better sound, but that's fine too by me: it might be that your system already is properly grounded throughout, so no additional benefit can be obtained.

[YashN]

6 minutes ago, sandyk said:

 

 As are the systems of those who believe that correct check sums guarantee that your cheap SMPS Laptop will sound as good as a very low electrical noise computer. All that the checksums guarantee is that you MAY be able to REGENERATE files that sound CLOSE to that of the original Master.

 

What's up?

 

Tell me about it. Been looking for some new cool gear to do multi-track recordings in my studio. Can you believe one manufacturer went from a Linear PSU to an SMPS in a new model of a multi-track interface and thinks they resolved an overheating issue like that?

 

So now, this is quite a common issue I have seen on the production side of things lately: various SMPS used in different pieces of equipment, even some new(ish) synths.

 

Mind-boggling, really.