UltraTap causing noise with pedal board power supply

[Scoodva]

Hello, Everyone,

 

I have an H90 and an UltraTap rack mounted in my studio and both units are powered off of a pedal board power supply that I built that give me an accessible on/off switch for when they are not in use. The PSU uses an SMPS which is heavily filtered and has a separate regulator for both the 12V and 9V DC outs. When both units are connected to the pedal board power supply, there is a constant tone that is generated out of both of the units. It’s not particularly loud but it is audible when mixing anything that has a quiet dynamic section. When I disconnect the audio from the UltraTap but leave the power connected, the noise is still emitted from the H90. When I disconnect the power from the UltraTap the H90 is dead quiet, even when monitoring and loud levels. When I connect a different pedal (Source Audio Nemesis) to the same DC out port where the UltraTap was connected the H90 was still noise free. I then connected UltraTap with a 9V wall wart and reconnected all the audio and now everything is clean, but I have to crawl behind the rack the turn the power off to the UltraTap. Lastly for a final test, I disconnected the H90 from the PSU and connected only the UltraTap and the audio from it is quiet. It is only when they are both connected to the power supply that the tone is generated.

 

After all of that, my question is has anyone had any issues with the UltraTap or other pedals in that particular series not playing well with other pedals on the same power supply? And though at first glance the words “power supply that I built” may cause many to point to the PSU as the issue, I have used this same power supply circuit for a bigger version for my pedal board that can power the following at the same time and all are noise free:

 

Electro Harmonix Pitch Fork

Source Audio Nemesis

Source Audio Ventris

Vox Wah

effectrode SR-71

Source Audio C4

Moog MF-105

AionFX Halo

Mod Electronics Seismic Shift

 

Like I said, when I plug a different digital effect pedal into the same DC out on the PSU that is also powering the H90, there is no noise. I suspect that there is something on the -VDC connection on the UltraTap that is causing this issue. I may also have a faulty pedal. For now the wall wart solution will be fine but I will want to sort this out soon and if not I will replace it with something else like a Source Audio Collider.

 

Thoughts?

 

Thanks!

 

Paul

 

[PRSGUY513]

I’m not wanting to start anything and the fact you built your own Switched Mode Power Supply says you know something about electronics. But I would not rule out the SMPS so quickly. I wish I could troubleshoot further, but these situations tend to be very device specific and it would probably turn into a rabbit hole online. I have built my own multi-voltage/output PSU’s but all are linear with multi secondary transformers and never have any problems. It’s been my experience that some digital audio devices are sensitive to EMI from PSU’s.

Could it be that you’re stressing the regulators with the added devices and inducing EMI from the SMPS or other areas? Looking forward to what might be causing this and a solution.

[Scoodva]

It’s definitely not the SMPS. Any EMI that could possibly be radiating from it are mitigated by shielding and distance. Also I did not build the SMPS. I built a PSU that uses an SMPS, which is an off the shelf component. The parts around it that I built involve the filtering and regulators. The regulators themselves are attached to heat sinks plus in this scenario only one pedal is connected to each regulator. The 12V regulator can handle up to 1.5A and the H90 draws 500mA at 12V. Same rating for the 9V regulator and the UltraTap draws less then 200mA. So regulators themselves are not being overworked.

 

The power supply that comes with both the H90 and the UltraTap are switching power supplies as well as a vast and great multitude of other digital gear in both the pro audio and instrument markets. Pretty much every piece of digital gear that has the PSU inside is using an SMPS. There may be some devices that are sensitive to these devices but those instances nowadays are somewhat rare.

 

Again, just for clarification, the following equations are tested to be true with the PSU being used:

 

PSU + H90 = No Noise

PSU + UltraTap = No Noise

PSU + UltraTap + H90 = Noise

PSU + H90 + Source Audio Nemesis = No Noise.

PSU + H90 + Audio Connected = Wallwart (SMPS) + UltraTap + Audio Connected = No Noise

 

The problem points strongly to the UltraTap having a flaw of some sort with the DC connection. I just don’t know if it’s with this particular unit or if this occurs when using other pedals in this same series sharing a pedal board power supply with other pedals.

 

Thanks!

 

Paul

 

[PRSGUY513]

Scoodva wrote:

Also I did not build the SMPS. I built a PSU that uses an SMPS, which is an off the shelf component.

I assumed this much. I was just making a passing comment as to try and start on the least confrontational path. Anyway, as I have run into so many times before, people are too sensitive to deal with this level online.

I will remind you of this. There are two types of EMI, radiated and induced. Shielding helps with radiated, but induced (induction) EMI is another beast. This is where the noise enters into the conductors. SMPS emit higher frequency EMI. Electro Magnetism can be an elusive mistress.

[PRSGUY513]

So the H90 and UltraTap does not use a wall wart and has a mains AC IEC plug that attaches to the device? A wall wart is not a built in PSU. Also, many wall wart devices are not switching. I’m willing to bet the H90 is not. The H9 was not.

[PRSGUY513]

I had wrote this part for those other than the OP, but deleted it for the sake of diplomacy. The more I thought about it the more I think it’s something to include because it ties in and is something that gets lost among the electric guitar community. Also, when a comment is made that everything uses switched mode power supplies and there is never any issues is very misleading. If you don’t believe open up your computer case or if it has a clear plastic window that’s usually all it takes and bring your plugged in guitar towards the computer and tell me what happens.

Here’s the original comment:

This is for all and any other guitarist who might be reading this. The crazy thing about an electric guitar with electro magnetic pickups, metal strings (wires) connected to another electronic device with a cable, is that if the ground is poorly connected or more than one path to ground with different impedance reference planes is created what essentially is devised is a giant antenna just asking for stray RFI and EMI to come make friends with the signal. 

[PRSGUY513]

…one final thought for the OP. This isn’t my quote, but the wisdom of someone much smarter than me and inventor of one of the most used guitar modeling devices around.

“check your audio cabling…99% of problems are due to bad cables”

[Scoodva]

These pedals are not being used with a guitar. They are being used as studio effects with a console. The PSUs with both UltraTap and H90 are SMPS wall warts. They take 100-240VAC in and output VDC respective to the needs of each pedal. And again, this problem only occurs when the UltraTap and H90 are connected to the same pedal PSU. A thorough process of elimination has narrowed the problem down to the UltraTap. So I am asking if anyone is using an UltraTap or another pedal in the same series with other digital pedals and connecting them to the same pedal power PSU and whether or not you are experiencing a noise issue.

 

Thanks!

Paul

[PRSGUY513]

Good Luck!👍

Remember there’s always the H9000 for the studio.

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