Safety And Design of DIY originated Audio Products

[Mivera]

Oh and here's the story of why Benchmark moved onto $10 ($5 in quantities of 500 units) SMPS's from linear supplies.

https://benchmarkmedia.com/blogs/ap...audio-myth-switching-power-supplies-are-noisy

Kinda blows my mind since the DAC 1 was already far better than the threshold of human hearing. Far better than Amir's APx could measure. Yet he's onto the DAC 3 now with game changing improvements each step of the way.

 

[Mivera]

Oh and look what we have here! Amir's other example of excellence has also moved on to $10 SMPS's. Amir is it still 2005 in Seattle?

 

[Mivera]

I wonder why these guys don't use $200 Japanese Daitron supplies? Especially since they're only $170 a piece if you order batches of 100 units.

Must be for reasons of engineering excellence that can only be found in China from $5-10 a pop.

 

[amirm]

Nothing.

So you have a center conductor carrying current and an outside "shield" that is not connected to anything.

What is the impedance of that shield relative to ground?

 

[amirm]

Oh and look what we have here! Amir's other example of excellence has also moved on to $10 SMPS's. Amir is it still 2005 in Seattle?

If you know what you are doing, of course you can use switchmode power supplies. The problem is that you have no engineering skills let alone enough to design with switchmode supplies.

In other words:

You are a lego builder. For you, there is nothing but hell dealing with complicated components like switchmode supplies.

For likes Benchmark where they have superb engineers, confirming their work with measurements that they publish, sure, they can and do use a switchmode supplies. As a beginner hobbyist, you need to avoid it.

Better yet, as I keep saying, you need to avoid dealing with mains altogether. It is illegal to export such product and puts your customers easily in jeopardy of risk of shock or worse. We have laws so that we can keep inexperienced people out of creating these situations.

 

[Mivera]

So you have a center conductor carrying current and an outside "shield" that is not connected to anything.

What is the impedance of that shield relative to ground?

I'm only using the shield for the reflective properties. There's 2 ways shielding works, 1 is reflection, other is taking the noise to ground. Since using shielded cable was overkill anyways, and it's connected directly to an EMI filter, the reflective properties were enough.

 

[amirm]

Oh and here's the story of why Benchmark moved onto $10 ($5 in quantities of 500 units) SMPS's from linear supplies.

https://benchmarkmedia.com/blogs/ap...audio-myth-switching-power-supplies-are-noisy

Kinda blows my mind since the DAC 1 was already far better than the threshold of human hearing. Far better than Amir's APx could measure. Yet he's onto the DAC 3 now with game changing improvements each step of the way.

Nope. We can measure them with ease because we use signal processing to reduce the noise level of ADC in the analyzer.

Here is JA with an analyzer similar to mine: https://www.stereophile.com/content/benchmark-dac1-usb-da-processor-headphone-amplifier-measurements

No problem whatsoever showing distortion spikes down to -140 dbFS.

 

[Mivera]

If you know what you are doing, of course you can use switchmode power supplies. The problem is that you have no engineering skills let alone enough to design with switchmode supplies.

In other words:

You are a lego builder. For you, there is nothing but hell dealing with complicated components like switchmode supplies.

For likes Benchmark where they have superb engineers, confirming their work with measurements that they publish, sure, they can and do use a switchmode supplies. As a beginner hobbyist, you need to avoid it.

Better yet, as I keep saying, you need to avoid dealing with mains altogether. It is illegal to export such product and puts your customers easily in jeopardy of risk of shock or worse. We have laws so that we can keep inexperienced people out of creating these situations.

Yes just like they confirmed the DAC 1 (which he proved himself in the video in the link I sent was noisier than hell) was as good as DAC's could get. Nothing could beat the DAC 1. Your example of engineering excellence was debunked by the manufacturer himself!!

But at the time it was for sale, the best APx machines couldn't measure better. And he even used a modern APx unlike the old clunker you have.

 

[Mivera]

The bottom line is these APx measurements are a joke when it comes to determining what's audible. All these machines are good for is QC. However so many manufacturers use this data for marketing, only to put their feet in their own mouths when it comes time to update the model.

 

[amirm]

And let's zoom into design of that DAC which Mike put forward:

Notice the direct and short path for the AC mains. No crap soft-start either. No spliced in noise filter:

Even your own evidence damns you over and over again Mike.

Ultimately though, we can only tell so much from pictures. So we measure and then the horrors of design pop out. Until you do that with your device and not keep pushing your head deeper in the sand, you have no case.

 

[Mivera]

And let's zoom into design of that DAC which Mike put forward:

View attachment 8379


Notice the direct and short path for the AC mains. No crap soft-start either. No spliced in noise filter:

Even your own evidence damns you over and over again Mike.

Ultimately though, we can only tell so much from pictures. So we measure and then the horrors of design pop out. Until you do that with your device and not keep pushing your head deeper in the sand, you have no case.

Yes because there was no room left in the budget after spending $5 on that Chinese SMPS. My main's filter alone cost more than that cheap SMPS! Probably wanted to cut cable costs down as well.

 

[Mivera]

And look at those shiny exposed mains connections!!! Imagine if a wire fell off and landed on them. Time to say hello to the ancestors!!!

 

[amirm]

I'm only using the shield for the reflective properties. There's 2 ways shielding works, 1 is reflection, other is taking the noise to ground.

I started to explain the math and physics but figured you won't follow it anyway. So instead, I did a quick experiment of your scenario of coax cable with shields not connected to anything.

I put on an RCA jack on a BNC adapter and hooked it up to my Tektronix scope:

In this case the shield was connected at one side (scope side). The output is very clean.

Now let's see what happens as I pull out the RCA just enough for the shield to disconnect as you say you are using:

Immediately we see large increase in both low frequency coupling (the large sinewave) and high frequency (general fuzziness of the waveform).

Let's do the test again, this time just draping it over the front display of the scope. Again, first with ground connected at the scope:

Very clean again. Now let's float the ground as Mike has:

Notice the large increase in high frequency components plus some spikes in the middle of the waveform which is deterministic (i.e. some oscillator inside the scope running at that frequency).

In other words, a floating shield is useless when it comes from shield against both low and high frequencies.

Yes, there is such a thing as reflective losses but that works on principles of plane waves, usually far field, etc. The metal enclosure for your audio gear works in that regard. Which would have been another reason to put the switchmode power supply outside.

This experiment took me 3 minutes to conduct. Mike doesn't have any instruments, nor would he know how to test anything with them. So instead, he goes by stuff he reads online and that is the most dangerous thing a novice could do.

These topics are complex. You can't become your own brain surgeon. The rules of thumbs for keeping things short, separate, etc. were created to guide the people who don't understand the topic but still want to produce good products. Mike flaunts all of that due to total lack of any design experience. And as a result, his work looks like frankenstein project to any experienced engineer.

 

[Mivera]

I started to explain the math and physics but figured you won't follow it anyway. So instead, I did a quick experiment of your scenario of coax cable with shields not connected to anything.

I put on an RCA jack on a BNC adapter and hooked it up to my Tektronix scope:

View attachment 8381

In this case the shield was connected at one side (scope side). The output is very clean.

Now let's see what happens as I pull out the RCA just enough for the shield to disconnect as you say you are using:

View attachment 8382

Immediately we see large increase in both low frequency coupling (the large sinewave) and high frequency (general fuzziness of the waveform).

Let's do the test again, this time just draping it over the front display of the scope. Again, first with ground connected at the scope:

View attachment 8383

Very clean again. Now let's float the ground as Mike has:

View attachment 8384

Notice the large increase in high frequency components plus some spikes in the middle of the waveform which is deterministic (i.e. some oscillator inside the scope running at that frequency).

In other words, a floating shield is useless when it comes from shield against both low and high frequencies.

Yes, there is such a thing as reflective losses but that works on principles of plane waves, usually far field, etc. The metal enclosure for your audio gear works in that regard. Which would have been another reason to put the switchmode power supply outside.

This experiment took me 3 minutes to conduct. Mike doesn't have any instruments, nor would he know how to test anything with them. So instead, he goes by stuff he reads online and that is the most dangerous thing a novice could do.

These topics are complex. You can't become your own brain surgeon. The rules of thumbs for keeping things short, separate, etc. were created to guide the people who don't understand the topic but still want to produce good products. Mike flaunts all of that due to total lack of any design experience.

The shielding wasn't even required. I only used it because I had a spool of it already.

And as I already said, unlike the other Chinese SMPS's used in other DAC's, the supply in the Purestream is completely isolated from the rest of the gear with the lid on. That side panel facing the DAC board butts right up against the lid. It's pretty much in its own self contained sub-enclosure. Besides that this supply has the lowest EMI emissions of any supply available on the market. Leaps and bounds less than any linear supply. Yet we still completely isolate from the DAC.

These are some of the reason our clients say the Purestream sounds better than anything short of the MSB Select DAC 2.

 

[pinkupanda]

These are some of the reason our clients say the Purestream sounds better than anything short of the MSB Select DAC 2.

So all your "clients" are with MSB Select DAC 2 ? You know how stupid you look with your comments ? If all your clients knew before you are playing with their safety they wouldn't have spend a dime on anything you have to sell.

 

[Mivera]

So all your "clients" are with MSB Select DAC 2 ? You know how stupid you look with your comments ? If all your clients knew before you wire playing with their safety they wouldn't have spend a dime.

No they don't all have that DAC, but it's the only DAC out of 25 Purestreams in the field that was reported to be slightly superior. And we have a list of over 30 top DAC's it was compared to. Many of them 5 figures.

You see only idiots would be concerned with safety after reading this thread. This is why we didn't sell any Purestreams to idiots. Also why we don't publish measurements, as this keeps idiots who think that's all that matters from buying our products. Win win all around.

 

[pinkupanda]

No they don't all have that DAC, but it's the only DAC out of 25 Purestreams in the field that was reported to be slightly superior. And we have a list of over 30 top DAC's it was compared to. Many of them 5 figures.

You see only idiots would be concerned with safety after reading this thread. This is why we didn't sell any Purestreams to idiots. Also why we don't publish measurements, as this keeps idiots who think that's all that matters from buying our products. Win win all around.

So far all you have done in this thread is hand waving without any material evidence of all the 30 "top" DACs compared.

 

[Mivera]

So far all you have done in this thread is hand waving without any material evidence of all the 30 "top" DACs compared.

We got all of the evidence we needed from our clients already. I'm not trying to sell Purestreams here. We are sold out. The product has been discontinued. It was only developed for beta testing the design concept.

 

[pinkupanda]

You see only idiots would be concerned with safety after reading this thread. This is why we didn't sell any Purestreams to idiots. Also why we don't publish measurements, as this keeps idiots who think that's all that matters from buying our products. Win win all around.

If you are playing with human safety you have no right to sell any of those garbage. stop all these stupid and nonsensical comments!

 

[Mivera]

If you are playing with human safety you have no right to sell any of those garbage. stop all these stupid and nonsensical comments!

Ha ha human safety. Yes this is why I didn't sell DAC's to folks of your intelligence. Better stay away from wall outlets when you have a knife in your hand. Don't put your finger in the toaster either.