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Beware switching PSU's...lesson learned... Modular Synthesizers
Old 6th February 2018
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Beware switching PSU's...lesson learned...

Mods if you need to "Moan Zone" this, then make a Modular Moan Zone please nobody else will care/understand...

Holy frickin poop on a popsicle stick, this week has SVCKED!

A few weeks back I ordered a Doepfer PSU3 to replace my blown PSU2. I ordered it knowing I was going to get the PSU2 fixed and eventually add it back as a 3rd PSU because I have been skirting the edge of capability (the reason the PSU2 blew in the first place I came to find out) as far as power.

Install PSU3, things seem ok at first. Install 3 new modules (Morphagene, BIA, G.M.O.) earlier this week and the whole world blows up. Nothing works right when it's plugged into the PSU3, or almost nothing. Grr. Not just Audio Damage modules or high-draw stuff. Lights are all on but nobody is home.

Take PSU2 to get fixed and have PSU3 (in empty case) to get looked at and have them both wired in as a happy family. My wonderful tech is usually a miracle man, he did the work (installed PSU3 on 3rd row and added a Thermistor to prevent the initial power-draw on startup, this is what apparently causes the issue with AD modules) and sent me home, but not before informing me about switching power supplies and how they are total sh1t for modular. he was in disbelief that Doepfer would discontinue the PSU2 that is linear and only offer the PSU3.

I get home, install the modules, and nothing works again. Lights are flashing weirdly and in colors they shouldn't. I am tearing the rest of my Homer Simpsonesque hair out.

Today I took the case back and we sat there and troubleshooted (troubleshot imo) the whole top row (PSU3 row) and found nothing wrong with anything until Tim (tech) removed the PSU3 again and noticed very thin solder beads on the main power rails or whatever on the PSU3. He flows a little solder over it and bam it works. All of it, including the AD stuff. I can go to band practice...

So either I bought a returned product that didn't work for anyone ever, or Doepfer needs to work on their goddamn QC. Either way I am pretty disenchanted right now. I bought all of this stuff from one retailer, including the Flame FX-16 that never worked right from the beginning. Come hell or high water I am never ordering another fvcking thing from there, period. I am not going to name who it is because I am not some flaming jerk who wan't to hurt ppl's business, but I am fvcking pissed off. Besides anyone who cares already knows who I am talking about anyway without me saying it...Between the Flame and these PSU's I spent 300 bucks in bench time getting it all working, and most of that was on the PSU3.

I am sure plenty of people have PSU3's that work fine. No need to defend your choices or yourself folks, I'm just venting. There are a lot of variables here- Mainly mine could have been used already, I wouldn't put it past this retailer. So grains for courses and a horse of salt and all that...at least there's a happy ending here....
Old 7th February 2018
  #2
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psu3 are switching? I thought they were linear.


googling it now, not finding much official. "Switching-to-linear regulation topology", what does that mean????
Old 7th February 2018
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Quote:
Originally Posted by oinkbanana View Post
psu3 are switching? I thought they were linear.


googling it now, not finding much official. "Switching-to-linear regulation topology", what does that mean????
It's like what it sounds like. See the picture below. The AC from the wall outlet is passed through those black rectangular boxes which are Meanwell brand encapsulated switching supplies and used to create +15v, -15v, and +5v. Then the + and - 15 volts are passed through linear regulators to bring the voltage down to +-12v (the linear regulators are underneath the heat sink fins) I haven't tried one but the idea is to use switching supplies instead of a heavy transformer to get the voltages in the ballpark and then use standard linear regulators to smooth it out.

Last edited by ImJohn; 14th February 2018 at 01:57 AM..
Old 7th February 2018
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subdo's Avatar
That really sucks slaughtrhaus. I've been deep in PSU woes and it's really frustrating. Right now I have a bunch of modules sidelined because I can't get enough clean power out of my racks. I think it's worth saying though that you can make a good switching PSU. My Pitts structure and 500 series Sweet Ten rack are both switchers and have been quiet and reliable. I think it just takes a little more work on the part of the manufacturers. I am surprised about the PSU3 giving you so many issues though. For the longest time Deopfer is the only PSU people would recommend. Maybe you just got a dud or the shady dealer sold you a dodgy unit to get it out of their inventory.
Old 7th February 2018
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That sucks about your Doepfer power, man. Sorry you've been going through so much hassle.
Old 7th February 2018
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Thanks for the sympathies guys, I actually really appreciate it. This was a really lame (albeit first world) debacle. I was super high on mania yesterday- My dog had major abdominal surgery (spay and gastropexy) too so there was a lot going on. I’ve slept about 4 hours in the past 48...

Band practice went off without a hitch I think, there’s a lot of noise in the room so some stuff was a little harder to test than others. I’m gonna listen back to it later today.

Post practice I’m feeling glad to have all this taken care of. I needed a 3rd PSU for the case mod I’m planning anyway so at least that’s done. Maybe I’ll be able to start my Twitch stream this week now...
Old 7th February 2018
  #7
that sucks! glad you got this sorted. very unlike Doepfer, but yeah, **** does seem to happen.

if any of you are looking for a PSU, check this out: L-1 Eurorack Power System
he has an XL one as well for large cases, and it's relatively cheap. quality is top notch
Old 11th February 2018
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A frequent GS poster knowing very well PSUs very recently posted a comment about switchmode PSUs with linear post-regulation, I'll try to find the post.

Personally for mains powered audio, including also instruments, I'd still prefer conventional linear regulated PSUs with the usual transformer. I don't care about a bit more energy required every year, I'm not an ecofreak. Unfortunately linear PSUs nowadays only represent a tiny part of all produced PSUs.

That said, the output voltage quality and generated RFI widely vary, some switchmode PSUs are not that bad but overall I still consider a good linear PSU to be a better option whenever a very clean output voltage is required (like audio or some demanding industrial instrumentation). Pre-regulation is mostly interesting for battery powered devices but the whole PSU system must be designed carefully (can't comment much details as I don't know switchmode PSUs very well, I never designed any).

For large consoles (several kVA, ending dissipating several kW) there could be measures implemented to save some energy by not powering the whole console 24/24 h but it's something to take in account when designing the consoles (sort of selective power off).
Old 13th February 2018
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Think you were just a tad bit unlucky there slaughtrhaus, at least your up and running now
Old 14th February 2018
  #10
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Quote:
Originally Posted by cane creek View Post
Think you were just a tad bit unlucky there slaughtrhaus, at least your up and running now
Even with my tech going through the PSU3 I have discovered 3 modules that simply won't work with it no matter what which has caused case planning mayhem until I get/make some longer power cables...
Old 14th February 2018
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Quote:
Originally Posted by slaughtrhaus View Post
Even with my tech going through the PSU3 I have discovered 3 modules that simply won't work with it no matter what which has caused case planning mayhem until I get/make some longer power cables...
Which modules aren't working?
Old 14th February 2018
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Originally Posted by ImJohn View Post
Which modules aren't working?
Moffenzeef G.M.O., Audio Damage AEverb MKII, and Rings was acting up earlier but then snapped out of it.
Old 14th February 2018
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Quote:
Originally Posted by slaughtrhaus View Post
Moffenzeef G.M.O., Audio Damage AEverb MKII, and Rings was acting up earlier but then snapped out of it.
Thanks. I know that the AEverb MKII has serious problems trying to run on power supplies where the +12v rail comes on a hair before the -12v rail does, typically switching supplies. For what it's worth I have Rings in both eurorack and 5U formats and running on different switching supplies (4ms and GRP) and have never had a problem with them.
Old 14th February 2018
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Quote:
Originally Posted by slaughtrhaus View Post
Even with my tech going through the PSU3 I have discovered 3 modules that simply won't work with it no matter what which has caused case planning mayhem until I get/make some longer power cables...

Quote:
Originally Posted by ImJohn View Post
Thanks. I know that the AEverb MKII has serious problems trying to run on power supplies where the +12v rail comes on a hair before the -12v rail does, typically switching supplies. For what it's worth I have Rings in both eurorack and 5U formats and running on different switching supplies (4ms and GRP) and have never had a problem with them.
Have you tried one of these?



WMD sells them for $30 a pop. It alleviated a lot of problems when I had that Synthrotek power supply.
Old 14th February 2018
  #15
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^^^ doesn't that just slow start the initial voltage spike as to not overload the PSU? [you won't overload the psu, but if you have too many modules spiking at start up, some of them just WON"T get the necessary starting voltage...]
Old 14th February 2018
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Originally Posted by Derp View Post
Have you tried one of these?



WMD sells them for $30 a pop. It alleviated a lot of problems when I had that Synthrotek power supply.
Didn't know they existed. Will look it up now, thanks!
Old 14th February 2018
  #17
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Originally Posted by oinkbanana View Post
^^^ doesn't that just slow start the initial voltage spike as to not overload the PSU? [you won't overload the psu, but if you have too many modules spiking at start up, some of them just WON"T get the necessary starting voltage...]
Yeah but it's simply NOT too many. Check my grid
slaughtrhaus current modular rig - Eurorack Modular System from Slaughtrhaus on ModularGrid
The PSU3 is running the top row and nothing else. It's running less than that actually because I had to switch some stuff around. Either way I am so far below any sort of draw limit it's ridiculous (according to my grid and my tech).

I'm just going to figure out the things that don't work with it and power them off other rows with flying busses so I can arrange the case exactly how I need to and not really worry about it. It "works", it's just a picky little princess snowflake like my 7 year old daughter acts sometimes.
Old 14th February 2018
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Slowing it down is exactly what the Soft Start does, but it works. Sometimes a module doesn't respond well to a voltage spike, and that will actually cause your whole system's power to freak out.
Old 14th February 2018
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Quote:
Originally Posted by Derp View Post
Have you tried one of these?



WMD sells them for $30 a pop. It alleviated a lot of problems when I had that Synthrotek power supply.
I've seen those but didn't try one because I doubt it would work in my cramped case and also I've read on Muff's of people trying them and it still not resolving the problem.
Old 14th February 2018
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Originally Posted by ImJohn View Post
I've seen those but didn't try one because I doubt it would work in my cramped case and also I've read on Muff's of people trying them and it still not resolving the problem.
And we trust Muff's because...

It worked for me. I just got sick of having to use workarounds, so I sold off any power that wasn't a uZeus.
Old 14th February 2018
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Originally Posted by Derp View Post
And we trust Muff's because...

It worked for me. I just got sick of having to use workarounds, so I sold off any power that wasn't a uZeus.
And you put on before the flying buss so it's on all the modules?
Old 14th February 2018
  #22
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Originally Posted by slaughtrhaus View Post
And you put on before the flying buss so it's on all the modules?
It won't handle the whole load, so you're supposed to put it in front of the troublesome modules. I got it to work with a whole buss before, though.
Old 14th February 2018
  #23
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Originally Posted by Derp View Post
And we trust Muff's because...
Because there are more experienced and knowledgeable modular synthesists there than here?
Old 14th February 2018
  #24
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Originally Posted by ImJohn View Post
Because there are more experienced and knowledgeable modular synthesists there than here?
I trust you when you quote muffs John! I find muffs UI really hard to read through even with search working, and with no upvotes convention it’s harder to get a consensus on some stuff.
Old 14th February 2018
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Agreed. I'll trust John before I trust anybody that willingly wiggles their muff!
Old 15th February 2018
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slaughtrhaus and Derp, thanks for the votes of confidence . . .it's nice to know someone out there trusts me more than I trust myself!
Old 15th February 2018
  #27
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Quote:
Originally Posted by slaughtrhaus View Post
Yeah but it's simply NOT too many. Check my grid
slaughtrhaus current modular rig - Eurorack Modular System from Slaughtrhaus on ModularGrid
The PSU3 is running the top row and nothing else. It's running less than that actually because I had to switch some stuff around. Either way I am so far below any sort of draw limit it's ridiculous (according to my grid and my tech).

I'm just going to figure out the things that don't work with it and power them off other rows with flying busses so I can arrange the case exactly how I need to and not really worry about it. It "works", it's just a picky little princess snowflake like my 7 year old daughter acts sometimes.
I'm gonna say you got a bum psu3.
Old 15th February 2018
  #28
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Originally Posted by oinkbanana View Post
I'm gonna say you got a bum psu3.
Possible, probable even. It was probably a returned item resold. After having my tech mess with it I’m stuck with it for better or worse. My eventual plan is to get rid of it and replace with a PSU2 if I can find some NOS but I have other fish to fry first.
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