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Hybrid power supplies (part linear part switching)
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Hybrid power supplies (part linear part switching)
Franktree
I tried searching but didn’t see any threads discussing this particular means of powering eurorack. I’m thinking of the Doepfer PSU3 and the Tip Top Studio Bus power supplies.

I know there’s a general sense that, on the whole, linear power is superior to switching, but what about this hybrid approach where the unit uses switching supply modules followed by a conventional linear regulator for the +/- 12v rails.

Best of both worlds? Worst of both worlds? No better than switching? As good as linear? I’d be interested to hear thoughts and experiences from those more in the know than me and/or folks with experience with these kinds of units.
Rex Coil 7
Franktree wrote:
I tried searching but didn’t see any threads discussing this particular means of powering eurorack. I’m thinking of the Doepfer PSU3 and the Tip Top Studio Bus power supplies.

I know there’s a general sense that, on the whole, linear power is superior to switching, but what about this hybrid approach where the unit uses switching supply modules followed by a conventional linear regulator for the +/- 12v rails.

Best of both worlds? Worst of both worlds? No better than switching? As good as linear? I’d be interested to hear thoughts and experiences from those more in the know than me and/or folks with experience with these kinds of units.
Actually, switching power supplies can be (and are) made to be very excellent sources of power. Better suited than linear in certain applications, really.

HOWEVER:

The problem is that it is very easy to make really shitty switching supplies, and switching supplies can be made at very attractive cost levels. That said, what happens is many people (too many people) shoot straight for the inexpensive ones ... moths to flames ... and then wonder why they've got problems developing as their systems expand or they use synth modules that are sensitive to crappy, noisey power.

High end switching supplies are out there, but a switching supply that is good enough for really producing the clean power that today's synth modules work best with will cost 2x, 3x ,5x more than a comparable linear supply.

So the blanket statement that says "switching supplies suck" is inaccurate .... "inexpensive switching supplies suck for use with modular synths" is a more correct statement.

Think about this; ... many folks don't bat an eye at buying a $25.00 switching supply (the "Meanwell" brand is popular). But would you put a $25.00 linear supply in your synth? Probably not. At least I would hope not.

Often times I'll read the argument from some folks that goes something like so; "yes, but such-n-such stereo power amps use switching supplies and those are some of the best upper-end power amps for audiophile stereo gear on the market". True, however the switching power supply in the $5k stereo power amp is not a $25.00 Meanwell.

Ampere for ampere, a switching power supply suited for modular synths will cost 3x more than a linear power supply suited for modular synths.

With all of that said, the problem isn't that switching power supplies are bad news. The problem is that it is very easy to manufacture inexpensive switching power supplies that work fine for many appliance-rated devices. Those low priced switching power supplies are often misapplied for use in modular synths by well intending end users that trust vendors who market low end switching supplies for use with modular synths. "But it's so-n-so Synth Parts R Us, surely they know what they're doing and they'd never mislead their customers ... right? ... so I feel safe buying this $25.00 power supply for my synth".

Many times synth vendors know less about what a good power supply is than their customers do. Or, more times than not, certain (as in "many") synth vendors are trying to attract the new user with low cost power systems. Such as low-end appliance rated switching power supplies, "soft bus" distribution systems, and ribbon cable module power cables. The lowest-end of low end power systems. This makes "getting into modular" more attractive for the new end-user. End result? SALES BABY $$$!!!

So it's not that "switching power supplies are bad", that statement requires qualifiers. More accurately stated, "Low end/low cost switching power supplies are bad for modular synths".

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Rex Coil 7
(PART 2)

More to your inquiry, there are some really REALLY excellent linear power supplies actually specifically designed for use with modular synths being offered by actual synth users which happen to be educated and experienced engineers these days.

Hinton Instruments definitely produces some of the best (if not THE best) linear power supplies specifically made for use in modular synths. Toroidal main transformers are used in his systems (the round shaped main transformer) which are superior to the square/block shaped transformers (less tendency to produce audible buzzing sounds that may be heard from across the room in some situations). There are other advantages the toroidal transformers offer as well. Graham Hinton has provided o-scope images of his power supplies' outputs both at idle as well as under load, both partial and full.

Metatronic Mods seems to be offering a linear power supply specifically designed and built for modular synths. This company is a newer member to the Miffwugglers forum, and best I can tell their power systems are newly developed as well. Power supplies by this company are equipped with toroidal main transformers. I cannot speak for what this company's power outputs look like on an o-scope under load and at idle since I've not seen anything depicting that yet.

There are probably a few other synth-specific linear power supply manufacturers (or possibly kit makers) out there.

That said, I don't see a reason for creating something that isn't needed. I'm referring to a hybrid linear/switching power system. Most likely, in the end, it would end up costing more than using purpose designed/purpose built linear power supplies.

IF you end up using more than one power supply, be sure to connect the two systems' zero volt rails together with very "thick" wiring. In a very basic way of thinking about that, you want to create a single zero volt rail (so to speak) by tying the two zero volt rails together of each power supply using very heavy wire. Perhaps three runs of 12ga wire in parallel as long as they're not too long. The longer the distance between between the two power systems, the more wire needed when connecting the two zero volt rails together.

Gaining an understanding that there is a difference between "ground" and "zero volt" is highly suggested so that the end user can make informed choices when setting up their modular synth system.

(NOTE: I've purposely avoided use of words like "bonding" and "coupling" as well as phrases such as "zero volt reference" or "grounding reference" to avoid confusing newer users and those unfamiliar with how certain electrical engineering terms are used).

cool

MARK27
I have found that I generally get what I pay for when it comes to power supplies and amplifiers and whatnot. I am currently saving my pennies for a Hinton system, but that will be later in the year at best. I currently have a power system cobbled together out of L-1 linear PSUs with LIBBs for distribution.

Regarding switching supplies for eurorack, I am very curious to hear anyone's experience with the ACL Bar PSU. It's a switching supply, but it certainly isn't cheap (> $500).

Anyone?
Rex Coil 7
MARK27 wrote:
I have found that I generally get what I pay for when it comes to power supplies and amplifiers and whatnot. I am currently saving my pennies for a Hinton system, but that will be later in the year at best. I currently have a power system cobbled together out of L-1 linear PSUs with LIBBs for distribution.

Regarding switching supplies for eurorack, I am very curious to hear anyone's experience with the ACL Bar PSU. It's a switching supply, but it certainly isn't cheap (> $500).

Anyone?
If you're wanting something for bench testing modules, or perhaps a VERY temporary setup until your Hinton PSU system arrives, there are a few that will get you through.

RE; that Audiophile Circuits League (aka "ACL") Bar-style PSU ... I would be careful of anything that I cannot see ripple/noise o-scope views of under load and at idle. Especially if you're asked to drop $500 bucks on it. I would wait until more information on it can be found or is published by ACL. I looked myself and could locate nothing of substance regarding that power supply's performance.

"There are lies ..... there are DAMNED lies ..... and then there are manufacturer's claims".

Words to live by.


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ablearcher
placing a little linear regulator after a switching supply is how all the eurorack switching power supplies I have seen work. It is not a "hybrid", it is standard practice and still requires significant filtering and careful layout.

my two cents is that if you have a large stationary system just get one of those power one or condor linear industrial power supplies, they are super cheap and excellent, just bulky and heavy, no reason to reinvent the wheel. After that read all the threads with hinton and dave jones about proper DC power distribution.

the only reason to use switching supplies for a eurorack system is for a portable case, and they can certainly work fine. They are used everywhere in industry with understanding that they are noisy and careful layout and filtering is required.
Rex Coil 7
ablearcher wrote:
placing a little linear regulator after a switching supply is how all the eurorack switching power supplies I have seen work. It is not a "hybrid", it is standard practice and still requires significant filtering and careful layout.

my two cents is that if you have a large stationary system just get one of those power one or condor linear industrial power supplies, they are super cheap and excellent, just bulky and heavy, no reason to reinvent the wheel. After that read all the threads with hinton and dave jones about proper DC power distribution.

the only reason to use switching supplies for a eurorack system is for a portable case, and they can certainly work fine. They are used everywhere in industry with understanding that they are noisy and careful layout and filtering is required.
Run a search in the forum regarding problems with Rene or problems with Pressure Points. Avoid the low cost switchers. Using a linear power supply that has a toroidal main transformer is not "reinventing" any wheels. The point of "going that far" is if you're going to do it, may as well go all the way. The Power One/Condor linear power supplies ARE "fine" (I happen to own three Power One models, two in 3amp/15v and one 3amp/12v myself). I posted the most desirable power supplies, and allow the reader to make their own choices.

Think of it this way .... you should be willing to spend AT LEAST 10% of the value of your modules on power systems. AT THE VERY LEAST 10% (20% would be more realistic). On a $5K modular 10% only comes to $500.00. That's less money than many oscillators these days. I mean, the Make Noise DPO sells new for $600 bucks for cryin' out loud. So if you're not willing to spend less on a power system than you'd spend on a single module, you've got your priorities all fuddup.

That five thousand dollar collection of modules deserves well though out power. Respect, yo!

So sure, you can go with a Power One linear PSU. But if you go just that one tiny step higher and use a power supply that was specifically designed for powering a modular synthesizer, designed and built by a modular synth user with an engineering degree, you'll never want for more. I mean, do your self a favor and at least spend an hour or two researching the power supplies made by Hinton Instruments, and even this "new guy" at Metatronic Mods ... it certainly can't hurt to at least give them a look/see, y'know?

Also it may benefit some readers to know that buying a Power One or Condor linear power supply will require ....

*** soldering.
*** figuring out how (and where) you're going to actually mount the PSU in your synth cabinet (Hinton power supplies may be mounted on rack mount rails, and come already mounted on metal plates ready to be racked up in back of your synth cab).
*** figuring out and installing power output meters (standard equipment on Hinton units, I can't speak for any others because I don't know).
*** working out basic shit like main input power fuses or circuit breakers and installing them in the system.
*** figuring out and mounting main power switch (to turn the synth on and off).
*** figuring out how the power jumpers across the power output turrets are configured to provide the correct output voltages.
*** figuring out the main power jumpers on the input turrets to configure the power supply to operate on the voltage coming out of the wall socket.
*** figuring out and soldering the input power wires to the power supply.
*** working out a method of covering those high voltage AC input connections so you or your CAT don't get the shit electrocuted out of them or yourself.
*** working out how you're going to connect the power supply to the DC distribution system.

So the initial moneycash saved on buying the Power One or Condor power supply is offset by the amount of labor involved to install and configure said power supplies. If you are DIY-skilled ... go for it. Do not underestimate the amount of labor involved! If you would rather buy the system, plug it all together without doing any soldering or figuring out how to mount all of that stuff ... then look closely at Hinton. VERY closely.

The Hinton (and best I can tell, the Metatronic Mod) units are plug-n-play. Send money, wait for Big Truck to drop the goods on your doorstep, turn a few screws, done.

Again, I cannot speak for Metatronic Mods because I've never dealt with them (other than sending an email that was not responded to). But I have dealt with Graham Hinton, more than once. He's helpful, very willing to be patient with your millions of questions, willing to make changes in the system just for you, and his power systems are VERY cost effective, given all that you get for your money. The only thing that ever gets in the way is goddam politics ... meaning how ever the currency exchange may affect the price of things (Hinton is in England).

Here's a link to a Power One PSU suited for Euro modular synths at Mouser to provide some idea of what kind of money you're looking at if you go with the DIY set up. Don't forget all of the other bits you'd need (fuses or breakers, power switch, wire, solder, and the "misc" list that seems to end up costing more than estimated in nearly any DIY project) ....

12v 3amp PSU - LINK = https://www.mouser.com/ProductDetail/Bel-Power-Solutions/HCC15-3-AG/?q s=sGAEpiMZZMtl%252b%2ft8G5TWgGQYpyG3MfPysjh23beaC4E%3d

12v 1.5amp PSU - LINK = https://www.mouser.com/ProductDetail/Bel-Power-Solutions/HBB15-15-AG/? qs=sGAEpiMZZMtl%252b%2ft8G5TWgGQYpyG3MfPyBJEi8sUvkOg%3d



Here's a link to Metatronic Mods website, specifically the info page for their power supply system...

METATRONIC MODS - LINK = https://www.metatronicmods.com/store/p9/PSU-linear-eurorack.html



Here's a link to Hinton Instruments power systems page. The "Full Power Dual" is for a system that does not need a 5v rail. The "Full Power Triple" is for a system that needs a 5v rail. Take note of how ready-to-go the whole thing is ...

HINTON INSTRUMENTS LINK = http://hinton-instruments.co.uk/paprod/psu/fullpower.htm

Hinton also offers complete custom designed/built bus bar systems, and high-end Euro module power cables. He can even put together an entire power system (PSU, Bus Bars, Cables) ... whatever you need, in whatever way suits your needs.




In the end ... it's your money, it's your synth, and it's your choice.

(I am not affiliated with, nor compensated by Hinton Instruments or Graham Hinton in any way or manner. I'm just an enthusiastic customer and user of Hinton Instruments' goods and services)


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Synthbuilder
Rex Coil 7 wrote:
Toroidal main transformers .... are superior to the square/block shaped transformers (less tendency to produce audible buzzing sounds that may be heard from across the room in some situations).

As with everything it's more complex than that. EI (block) transformers can be just as quiet as toroidals - it's just that there's a lot of cheap EI transformers out there.

Toroidals can hum (acoustically) quite badly if there is any DC component on the AC power line. Which can happen quite often where I live - the whole village runs on a single phase.

Leakage current and noise isolation can be better on a EI transformer. You can also easily build in substantial high voltage isolation when your primary and secondary can be wound onto different parts of the bobbin - that's not easy with a toroidal. You can put a screen in between the primary and secondary windings on a toroid but it's not common.

Mounting is easier with a toroid but EIs can be mounted more securely for rough handling.

Toroidals can be more easily damaged so not so good if your transfomer is open to accidental abuse. A safety screen is a good idea.

Toroidal lead outs (the wires connected to the windings that the user connects to) can be quite fragile when compared to the pretty sturdy tags on an EI.

Power on surges seem to be larger with a toroidal transformer compared to an equivalent EI.

I also have a feeling, borne out solely by experience rather than by any measurement, that the radiated field from a toroid is indeed weaker but is more concentrated closer to the core. So placing a toroid very close to a sensitive circuit may cause more problems than a EI would.

I usually use a toroidal though - they're efficient, space saving and for the money they are usually quieter.

Tony
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