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Internal PSU - so space isn't the issue...

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Re: Internal PSU - so space isn't the issue...

Postby ef37a » Thu Jun 06, 2019 8:37 pm

An another thing!!
I have been banging a drum for AGES about the loss of MIDI ports on AIs. OT? you'd think but, bear with...

Much the same arguments re internal supplies i.e. cost, space. And yet some very low cost, sub £100 AIs have had DINs and some pretty expensive ones not. Again, little rhyme or reason.

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Re: Internal PSU - so space isn't the issue...

Postby James Perrett » Thu Jun 06, 2019 10:02 pm

Folderol wrote:I've used these for all sorts of things. Small, cheap (even from RS) and all compliance issues taken care of. All it takes is some enterprising company to stick this on an angle plate prewired with a couple of output tails and a fused IEC chassis plug.

I would have thought that something like the one at

https://uk.rs-online.com/web/p/embedded ... s/1812202/

would be more appropriate with all the high voltage parts encapsulated (though you'd still need a fused IEC inlet). Only a fiver plus the cost of the IEC connector and probably far cheaper than that from a distributor set up to deal in higher quantities.
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Thu Jun 06, 2019 10:42 pm

James Perrett wrote:I would have thought that something like the one at
https://uk.rs-online.com/web/p/embedded ... s/1812202/
...
Which constituency are you standing for? I'll vote for you! :clap: :thumbup:

You guys are great! :bouncy:
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Re: Internal PSU - so space isn't the issue...

Postby ef37a » Fri Jun 07, 2019 12:36 am

James Perrett wrote:
Folderol wrote:I've used these for all sorts of things. Small, cheap (even from RS) and all compliance issues taken care of. All it takes is some enterprising company to stick this on an angle plate prewired with a couple of output tails and a fused IEC chassis plug.

I would have thought that something like the one at

https://uk.rs-online.com/web/p/embedded ... s/1812202/

would be more appropriate with all the high voltage parts encapsulated (though you'd still need a fused IEC inlet). Only a fiver plus the cost of the IEC connector and probably far cheaper than that from a distributor set up to deal in higher quantities.

Yes, all very nice but you still have mains volts coming into the equipment and that is where the regulations and handling problems lie.
You need the PSU totally insulated with just IEC one end and DC the other and not part of the case or chassis. Like my ex printer, almost.

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Re: Internal PSU - so space isn't the issue...

Postby johnny h » Wed Jun 12, 2019 3:22 pm

In my discussions with gear manufacturers, its a lot simpler to gets certification around the world when using external PSUs. Also its very easy to change an external power supply at a late stage, or even in later revisions (like with the Waldorf 4-Pole moving from 9v to 12v when part shortages necessitated different filter chips).
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Wed Jun 12, 2019 3:31 pm

If you're a company that sells 'professional' electrical devices around the world I EXPECT you to make the effort to get whatever internal PSU certification is required. You do this because you want to give me the best tools to do my job, and you want to make life easier *for me*.

Anything short of that means that you're taking the 'easier' route for yourself, and you obviously don't give a stuff what I think or need - so you don't deserve my money. Simple! :tongue:

P.S. This makes for interesting reading...
https://www.rane.com/rap.html

Here's a company that was prepared to admit they got it wrong by using an external PSU, and express their regret to their customers. That's a gold star to Rane in my book. :clap: Would that they all would come to this conclusion and had this humility.
(I actually swapped out my old Rane SM82 for a newer, internal PSU, version for this very reason, long before I saw this document.)
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Re: Internal PSU - so space isn't the issue...

Postby Hugh Robjohns » Wed Jun 12, 2019 4:27 pm

johnny h wrote:In my discussions with gear manufacturers, its a lot simpler to gets certification around the world when using external PSUs.

There are different rules and regulations around the world for boxes that have a low voltage DC power input as opposed those with a mains power inlet.

So it's typically much easier, quicker, and cheaper for manufacturers to design, build, and get approved status for products with DC power inlets and then ship them with a bought-in and already type-approved third-party wall-wart or line lump mains supply. It also allows the chassis to be smaller and lighter, which may be another key consideration in some cases.

Obviously, this approach is often not very convenient for the end-users, as the Elf has said very clearly, but that may not be a consideration that features high on the manufacturers' priority lists... at the moment... Time-to-market and retail price are probably much stronger motives for most, compared to the loss of a few potential sales to users who strongly object to external PSUs.

If more of us objected more vocally -- like the Elf -- then maybe the manufacturers would change their approach. It's already been pointed out that plenty can and do build universal mains supplies into their products, either with type-approved third-party units or their own in-house designs. So it can be done... but it does involve a real cost penalty which the end user will have to be prepared to pay for.

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Re: Internal PSU - so space isn't the issue...

Postby Hugh Robjohns » Wed Jun 12, 2019 4:42 pm

The Elf wrote:Anything short of that means that you're taking the 'easier' route for yourself, and you obviously don't give a stuff what I think or need - so you don't deserve my money. Simple! :tongue:

That seems an entirely reasonable and rational argument, and one I wholly support.

Here's a company that was prepared to admit they got it wrong by using an external PSU, and express their regret to their customers.

Erm... I think that's an interesting spin you've put on it!

In fact, Rane worked very hard to persuade the entire industry -- through the AES standards body -- to adopt a universal external power supply system, and made some very good arguments for the concept. It failed to gain international standards status simply because it was just too complicated to get widespread agreement on the most appropriate format to adopt.

The regret expressed in that specific document was not that they used an external supply for some of their products at all, but rather that a specific external supply they bought in from a third-party was no longer available because it couldn't comply with current international regulations...

However, the fact that they subsequently decided not to build mains supplies directly into their entire range of current products (presumably still using bought-in modules) is a happy outcome... but I'm not convinced it was directly as a result of the RS1 going obsolete....

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Re: Internal PSU - so space isn't the issue...

Postby blinddrew » Wed Jun 12, 2019 5:21 pm

Hugh Robjohns wrote:but it does involve a real cost penalty which the end user will have to be prepared to pay for.
Nail. Head. Hit.
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Re: Internal PSU - so space isn't the issue...

Postby johnny h » Wed Jun 12, 2019 5:33 pm

Hugh Robjohns wrote:In fact, Rane worked very hard to persuade the entire industry -- through the AES standards body -- to adopt a universal external power supply system, and made some very good arguments for the concept. It failed to gain international standards status simply because it was just too complicated to get widespread agreement on the most appropriate format to adopt.
It doesn't seem a very good idea to me. I mean, when you have something like a Moog One or a Jomox Alphabase (which needs 2amp @ 12v) vs Roland Boutiques on 5v or small monosynths requiring very little power, the whole system would be end up even more complicated than the problem it was supposed to solve.

Behringer managed to put an internal power supply on their economy DeepMind synth. Did they get enough credit for this? If not, manufacturers will continue to serve up more awful wall wart mess.
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Wed Jun 12, 2019 5:36 pm

I'm unconvinced it adds much cost. How much of a KT76's 150 quid is the PSU? A tenner?

To every manufacturer reading this: Add 50 quid for an internal PSU and I'll pay it every time.
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Wed Jun 12, 2019 5:42 pm

johnny h wrote:Behringer managed to put an internal power supply on their economy DeepMind synth. Did they get enough credit for this?
They did from me! Good on 'em! Even on the budget and diminutive DeepMind 12D and the new lightweight VC340. Great design choice, Behringer! :thumbup:
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Re: Internal PSU - so space isn't the issue...

Postby Hugh Robjohns » Wed Jun 12, 2019 5:55 pm

The Elf wrote:I'm unconvinced it adds much cost. How much of a KT76's 150 quid is the PSU? A tenner?

It's not just the physical cost of the power supply unit or components, it's also the design time and the testing time -- and all the associated resources. Those have real cost implications and lengthen the time it takes to bring a product to market -- something which is often critical in the more competitive parts of the market.

I'm not trying to defend the use of external PSUs -- I hate them as much as everyone else -- just explain some aspects of the other side of the coin.

To every manufacturer reading this: Add 50 quid for an internal PSU and I'll pay it every time.

Yes, sure, I might too... But how many other potential purchasers would? The vast majority of people seem to prefer to buy from internet box-shifters rather than support their local high-street retail stores just to save significantly less than £50!

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Re: Internal PSU - so space isn't the issue...

Postby Folderol » Wed Jun 12, 2019 7:20 pm

That cost is actually a significant over estimate, and I speak from direct personal experience.

I was responsible for the design of an industrial counter system which had to be fully isolated and capable of being powered by mains or 24V AC or DC. I spent very little time on the PSU. I simply allocated a large area on the PCB with a network of pads and trackwork. All that was then necessary was to solder in the appropriate off-the-shelf PCB mountable unit and wire to a standard IEC chassis plug, or required DC connector. This system also future proofed against obsolescence.

The whole area then had a plastic ventilated cover with the usual lightning strike warning. This lot was then inside the overall either plastic or stainless steel case, along with display, switches and connectors for sensors/controllers etc. The PSU modules we used retail for between £15 and £30 for an output drive current range of 1A to 5A at 24VDC. The firm was selling the counter for between £850 and £1200 depending on features.

Finally, dozens of these have been accepted by some of the most critical of all industries, i.e. medical leaflet printers. Their insurers are extremely fussy about both cleanliness and safety.
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Re: Internal PSU - so space isn't the issue...

Postby James Perrett » Wed Jun 12, 2019 8:48 pm

Folderol - did you have to have those units tested by a third party testing house for safety or did you just follow the rules and certify them yourselves? Or does the power supply's certification cover the whole unit? I'm just trying to get some idea of how much bureaucracy is involved.
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Re: Internal PSU - so space isn't the issue...

Postby Folderol » Wed Jun 12, 2019 10:04 pm

All the modules we bought in had multi-region certification (although we were only selling within Europe) and for the mains ones we self certified the wiring between the module and the and the mains chassis plug. The mains cable itself carries it's own certification.

We kept copies of the certification documents of all the modules we used and dated records of which were used in which counters. We CE marked alongside the socket, earthed the steel cased ones and marked the plastic cased ones as double insulated.

One of the pharmaceutical companies did their own checks on the first one we sold to them, and never said a word. We only found out because one of our guys was friends with one of theirs :)

They were more rigorous over the missing print detector we also made but not regarding safety - blank instruction documents result in serious trouble for everyone concerned.

By the time I retired, much of this was becoming moot, as the machine makers were starting to fit their own camera based systems to almost everything by default, rather than as paid options.
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Re: Internal PSU - so space isn't the issue...

Postby James Perrett » Wed Jun 12, 2019 10:42 pm

Folderol wrote:All the modules we bought in had multi-region certification (although we were only selling within Europe) and for the mains ones we self certified the wiring between the module and the and the mains chassis plug. The mains cable itself carries it's own certification.

So it would appear that partnering the approved power supply module I linked to above with an approved fused inlet with a suitable PCB layout in between would be sufficient.
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Re: Internal PSU - so space isn't the issue...

Postby Folderol » Thu Jun 13, 2019 7:43 am

As a qualified employee of an established electronics company, yes.
As a private individual (if intending to sell the complete product) I would suggest getting advice, and at the very least provide a detailed statement as to why you consider the interconnections to be safe, and what protection you have included.
e.g. Do the tags on the socket have insulating boots? How much damage can the outer case sustain without exposing high voltages?
These days you are expected to provide some protection for people servicing the equipment, as well as for ordinary users.
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Thu Jun 13, 2019 7:59 am

Hugh Robjohns wrote:
The Elf wrote:I'm unconvinced it adds much cost. How much of a KT76's 150 quid is the PSU? A tenner?
It's not just the physical cost of the power supply unit or components, it's also the design time and the testing time -- and all the associated resources...
All included in that tenner - I'm not just assuming the hardware (which is probably 2 quid's-worth!).

Hugh Robjohns wrote:I'm not trying to defend the use of external PSUs -- I hate them as much as everyone else -- just explain some aspects of the other side of the coin.
I'm aware, mate. And rightly so - I think you know we're both playing devil's advocate! :wink:

Hugh Robjohns wrote:The vast majority of people seem to prefer to buy from internet box-shifters rather than support their local high-street retail stores just to save significantly less than £50!
And they will reap what they sow.

Edmund Burke — 'Nobody made a greater mistake than he who did nothing because he could do only a little.'
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Re: Internal PSU - so space isn't the issue...

Postby ef37a » Thu Jun 13, 2019 9:03 am

Will knows that I hold him and his technical expertise in the highest regard but, his example is rather "industrial".

The murky, cut throat world of domestic/prosumer audio electronics is rather different.
Once you put mains power inside a device that will be built and tested in its tens of thousands on an assembly line by largely non-technical personnel the costs and logistics get sticky.

I do understand the objections of the professionals and working musicians but of course, they only form a tiny part of the buying population and as been said, Peeps want CHEEP!

Just to throw another branch on the fire? I guess nobody wants to go back to captive mains cables? Well, you have to remember to bring the IEC for the amp or clover leaf for the lappy!

Oh! Just come to me. No pro gigs without as much backup as possible ("The Show must..." an all that swaddlin') ? Buy a spare PSU!

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