Strymon power supply issues


At some point last year I started to hear from a couple of colleagues that Strymon power supplies were causing issues with some pedals that use digital chips. They would lock up when powered up. Users needed to unplug the power from the pedal and plug it back in to get the pedal working properly.

As Strymon supplies are becoming even more ubiquitous and we have a lot more pedals out in the world, it has slowly become something that I have started to hear about directly from a couple of customers.

Needless to say, we love our customers, you mean the world to us, and we want to make sure no one ever has any issues with any of our products. So I just want to let you know, it’s something we are aware of. We put something in place straight away to minimise any issues and are working on a solution that will make it easier on our production and QC process.

So, what’s the (technical) issue?

Strymon supplies are designed to not give out 9V instantly, they ramp up from 0V to 9V slowly enough that it causes some digital chips to have a ‘brown out’ and latch up because they aren’t seeing the 9V they are expecting to see on start up.

This ramp up design is to protect the power supply itself against faulty pedals, it just so happens that it also has this unwanted side effect for some digital stuff. Obviously Strymon pedals take this into account in their power section.

Every Strymon power supply with take a certain amount of time to ramp up its voltage to 9V, and every LFO chip will have its own start up time that it needs to see that 9V within. If this is a mismatch then the LFO locks up. The difference is in the milliseconds, but it still has an effect.

I contacted Strymon directly and they have confirmed this.

I have a Strymon power supply should I throw it in the trash just to be sure no bad things happen?

No. If you haven’t had any issues with your Strymon supply, then you’re fine.

I want to be clear that I don’t think Strymon supplies are bad, and I’m certainly not saying to not use them. They are well designed, solid units.

They just cause us an issue that we need to work around. I’ve written this article to make sure our customers understand the situation and what we’re doing about it.

See below.

Does it happen with every Champion Leccy pedal and every Strymon supply?

No. If you are using a Strymon supply with a pedal that uses a digital chip and haven’t had an issue, then you’re fine.

Yes. The voltage ramp up is a feature of every Strymon supply (at the minute).

No. The issue only potentially affects our modulation pedals that use an LFO. At this time, that means the Woozy, the Skitter and the Kilter only.

None of our pedals or devices have ever had an issue with any other power supply.

Is it possible I’m having this issue and I’m not aware of it?

No. There’s no chance of that happening.

When the LFO locks up there is no modulation. The LFO indicator light does not change, it’ll either be always on or always off.

Does it happen with other pedal brands?

Yes. It has affected a bunch of digital chips (including the LFOs we and a few other brands use), so potentially it can affect anything that has one. We know of a couple of brands that have had issues.

Will a brown out damage the pedal?


How many people will this affect?

Very, very few. Hopefully no more going forwards.

Just to be clear, of the 900 plus modulation pedals we currently have out in the world, we’ve had fewer than 5 issues that required the LFO replacing.

What are you doing about it Woolly?

Last year, when it became clear that this might become an issue, I bought a Strymon power supply to test every single pedal against during QC.

Out of the several hundred units we’ve sent out since we started testing against the Strymon unit, we haven’t (touch wood) had any issues . If one does happen to slip through, we will of course gladly sort it out, and replace the LFO.

We’ve put all of the LFOs that didn’t pass the Strymon test to one side for the time being whilst we work on a new power section with a slow start up to help us skirt the ramping issue, so we don’t have so much waste.

So yes, we are working on a new power section. It’s going to be very fancy pants, but won’t really affect anything other than helping us save time in QC.

Once we’re happy that it works like we want it to, it’ll make testing and burning in a lot easier for us and we can get back to using those LFOs that failed the Strymon test.

As we have a strategy in place it’s not an urgent priority, but it is something we want to have sorted sooner rather than later. Sometimes we make adjustments like these to the PCB without announcing them, because nothing really changes with the circuit, we’re just making production easier for ourselves.

The biggest potential hurdle for us at the minute is availability of parts for that new power section. Supply chain issues are likely to be an issue well into next year. So it’s something we’re slowly chipping away at.

If you have any concerns or questions shoot us an email!

2 Comments Add yours

  1. Sam says:

    Is this similar to the issue Keeley was having with earlier batches of its Halo pedal? If so, they fixed the problem by changing two capacitors in their pedal.

    “Howdy Folks!
    Thanks for the super kind words on the Halo. The sound quality of this pedal is something I had only dreamed of. During the past six months of development at least a dozen Halo pedals were used in a live environment and no power supply related problems from Andy or any of the YouTube demo artists were reported. I hadn’t noticed any compatibility issues even though I own Strymon power supplies at both my home and office where I’ve used the Halo for over a year. There appears to be three or four power supplies that can cause the Halo to fail on start up. What we have found is that the Halo demands a lot of current upon initial power up, and if a switching type power supply hesitates upon the initial load, the Dream IC in the Halo will fail to initialize. The problem clearly resides with some very small tolerances coming into play. As soon as we were made aware of the issue we solved the problem the same day by simply changing two capacitors in the power section. If your Halo is not working with a particular switching power supply (Strymon, Fender, or TheGigRig Generator), please report it to Sean Spears through our Keeley Service company email, and we will take care of you immediately. In general, most power supplies will power the Halo just fine and they include: VooDoo Labs, Walrus Phoenix, MXR DC Brick, BOSS PSA-120, OneSpot, Donner, etc, etc. I’m very sorry for any troubles caused while starting to enjoy your new Halo Dual Echo. If you have a problem with your pedal, let’s get it swapped out for a new one. Thank you very much for your business, we’re standing by to help you with any problems you may have.

    Robert Keeley”

    1. Woolly says:

      Almost certainly. I am pretty sure that the capacitors they are talking about are filter capacitors. When the pedal sees power, those capacitors need to charge up. It takes a fraction of a second, but in some cases it’s enough. When that takes a tiny bit too long the IC doesn’t see can’t pull enough current and so locks up. It all comes down to tolerances of several parts and their combined effect.

      I actually dropped the size of one of the filter caps down before I was having issues, which may have saved me more headaches, but it turns out in my case the biggest issue was that one batch of the LFO ICs that I use were just ever so slightly out of spec that a few of them were suffering this issue with the Strymon supplies. It lasted over about 200 units, but I’ve been through another several hundred since then and only one has failed. I wonder if shake ups to the supply and demand and working patterns in general caused some QC issues. I’ve definitely had to be a lot more wary about checking and testing components in the last couple of years.

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