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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 Hugh Robjohns » Thu Jun 13, 2019 5:37 pm

ef37a wrote:Ha! Bet they would not have done it for me!

They would have, actually -- it was a mod they were prepared to offer to special order because they appreciated the sense of it. As I said in my review:

Hugh Robjohns Review wrote:One final point worthy of mention: a persistent issue I have with digital meters is the way most fail to indicate the normal operating range and safety headroom margin in an operationally useful way. The standard A2D2 does better than most in this respect, with the top six meter segments glowing yellow to warn of incursions into the headroom zone. However, with such a large and detailed scale, I felt there was a better option... and after discussing this with Drawmer I'm delighted to say that the company were very willing to supply a unit to my precise specifications. As a result, I bought a customised unit, which is now installed in my test reference system. The 'Robjohns Meter,' as I believe it is known in Wakefield, uses green LEDs from ‑50 up to ‑20dBFS, yellow from ‑18 to ‑9dBFS, and red all the way up to zero. This arrangement conforms with the broadcasting level standards (alignment level of ‑18dBFS and maximum permitted level of ‑9dBFS) and makes it very easy to see at a glance when signals are sitting in the 'normal' yellow region, and when they have crept into the (red) headroom margin.

https://www.soundonsound.com/reviews/drawmer-a2d2

Dramwer A2D2 standard meter.png
Standard Meter

Drawmer A2D2 Robjohns meter.jpg
Robjohns Variant meter

It can be a dangerous practice commercially.

Yes, it can. But that specific example it simply involved altering the relative numbers and positions of different coloured LEDs when stuffing the boards with components, which isn't that big a deal. For a one-off like mine, it was done by hand during the build without too much of a cost penalty, but if required for larger numbers it could be done with altered instructions for the component stuffing machines, again with no cost penalty assuming the different coloured LEDs cost the same price. I believe there were a number of subsequent orders for 'the Robjohns meter' version. ;-)

Word was these favours were in danger of sinking the company.

Ah yes... 'favours' are dangerous. But properly costed 'mods', 'one-offs' and 'bespokes' shouldn't be a problem, provided the company has the flexibility and resources to deal with them efficiently -- and that the product is designed in such a way that allows such tweakery. Not everything does, of course, but some products are designed from the outset with customisation very much in mind.

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

Postby blinddrew » Thu Jun 13, 2019 6:05 pm

Folderol wrote:They are also potential kit murders :(
Who can honestly say they have never plugged one in with the wrong voltage/polarity? It is especially easy to do in precisely the gig situation.
Yep, fried a fender tuner pedal like that. :(
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Re: Internal PSU - so space isn't the issue...

Postby Sam Spoons » Thu Jun 13, 2019 6:16 pm

Boss pedals seem pretty robust in the face of non-regulated PSUs. For some bizarre reason the Boss PSU that came with my MicroCube is un-regulated and punts out 13V with no load. I did not realise and powered my Peterson StroboStomp from it which instantaneously popped....... Can't understand why all pedals don't have a built in regulator to protect them (well, I can actually, it's called 'profit').....
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Re: Internal PSU - so space isn't the issue...

Postby Folderol » Thu Jun 13, 2019 6:19 pm

"and that the product is designed in such a way that allows such tweakery."

This is the core of good design. It increases the initial development costs, but further down the line, more than pays for itself when variations are wanted, or specific components become unavailable. Unfortunately becoming a rare occurrence :(
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Re: Internal PSU - so space isn't the issue...

Postby The Elf » Thu Jun 13, 2019 6:24 pm

I've had custom nips and tucks from various manufacturers over the years. One of the old 'Big Three' used to be particularly helpful in this regard, though their ability to do so has been squeezed over the years. Drawmer even created a special version of their M500 software for me, but then I live about 20 minutes from the factory, so I'm a bit blessed there! :lol:

Yes, it costs, but I've always been prepared to pay a fair price. I'm not saying every manufacturer should offer this, but it's nice when they can. I'm in no way suggesting that in my my example above they *should* have agreed to do a mod for me, but I think it would have been a nice gesture to at least have given it consideration, at additional cost, given the figures involved.
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Re: Internal PSU - so space isn't the issue...

Postby Eddy Deegan » Thu Jun 13, 2019 8:37 pm

ef37a wrote: I guess nobody wants to go back to captive mains cables?

Are they not just an internal PSU without an external socket? If you mean devices where the mains cable disappears into the unit directly, I'd prefer an external PSU (even though I'm with Elf on preference for IEC sockets).

The SY85 has a captive cable and while in normal operation it's no biggie, the pressure exerted on the cable by the grommet which clamps it is way too high (I've had to replace two cables over the years for this reason) and when I was a gigging musician it was a pain. Apart from being awkward, the number of times I stepped on the plug during setup/wrap-down was ridiculous!
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Re: Internal PSU - so space isn't the issue...

Postby ef37a » Thu Jun 13, 2019 8:51 pm

"They would have, actually -- it was a mod they were prepared to offer to special order because they appreciated the sense of it. As I said in my review:"

Well maybe Hugh but I am sure you got my drift? IN GENERAL an audio company is much less likely to listen to a crumbling old amp jockey in the sticks than the prestigious technical editor of the premier audio magazine on the planet!

But yes, I learned my trade when retailers had a close association with manufacturers. In a large town a few dealers would mainly stock Philips, B&O (bstds to fix!) Grundig. Another couple would be Rank Bush Murphy, Ferguson and they all had a smattering of Japanese kit later on. These firms would request fault reports so that problems could be fed back to the design department and also disseminated to other dealers saving them diagnostic time.

I suppose there is a bit of that left at the high price end but mostly, once the warranty runs out they don't want to know. Sometimes hard IN bloody warranty from a few reports I have read!

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

Postby Folderol » Thu Jun 13, 2019 10:17 pm

Ha! Memories :)
I can remember when Radio Rentals still sent us out to repair ancient radios that were still rented by little old ladies. Only this wasn't a rip-off, the old dears would never dream of owning such a thing, and hadn't noticed they were getting excellent service for only a shilling a month :lol:
You don't get service anything like that these days.

One particular fond memory I have was when I was sent out on one of these calls. The fault was just a broken drive cord, but without giving it a second thought I replaced the dead dial lights too.
When I called the lady in she cried out with her hands up to her face. Needless to say I was worried until she said in a sort of awed daze "It's all lit up! It's never been lit up."
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Re: Internal PSU - so space isn't the issue...

Postby Sam Spoons » Thu Jun 13, 2019 11:38 pm

Back in the '70s I worked for a TV rental company in the NW, Telefusion. I was a salesman and, later, shop manager in South Manchester. We covered a both the most affluent (Hale Barnes) and most impoverished (Sharston/Benchill) areas in the region. We had an installation tech based at the shop and the once a week job we tried to avoid (by going to the pub) was our debt collection evening. We'd knock on a couple of doors and then go and spend the (£7 IIRC) expenses on beer........ The tech was the longest served on the staff so he knew which addresses were worth a knock and which to steer clear of (big dogs/husbands) and he had the van...........
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Re: Internal PSU - so space isn't the issue...

Postby Martin Walker » Fri Jun 14, 2019 5:10 pm

Sam Spoons wrote:Boss pedals seem pretty robust in the face of non-regulated PSUs. For some bizarre reason the Boss PSU that came with my MicroCube is un-regulated and punts out 13V with no load. I did not realise and powered my Peterson StroboStomp from it which instantaneously popped....... Can't understand why all pedals don't have a built in regulator to protect them (well, I can actually, it's called 'profit').....

There are a huge number of unregulated PSUs out there that are chosen so that when plugged into the device they are partnered with, the loaded voltage drops to a suitable value.

IN the case of a power amplifier like the ROland Micro Cube, this load will be hefty, so the unloaded voltage will probably be considerably higher than when the MIcro Cubse is running - hence your StroboStomp going pop.

And yes, its largely down to profit margins, since it's far cheaper to use an unregulated PSU and regulate it yourself inside the device.


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

Postby Sam Spoons » Fri Jun 14, 2019 5:44 pm

Boss pedals all insist on a regulated PSU (Boss PSA 240, now the PSA 230ES) but it's an extra. I guess the PSU with the MicroCube is included they saved money.
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Re: Internal PSU - so space isn't the issue...

Postby Folderol » Fri Jun 14, 2019 7:00 pm

The irony is that modern switch mode PSUs are not only smaller, fully regulated and universal input, they are also cheaper to manufacture!
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Re: Internal PSU - so space isn't the issue...

Postby Sam Spoons » Fri Jun 14, 2019 7:25 pm

:headbang: :headbang: :headbang:

OTOH that'll be why they called the PSA230 into existence......
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