Noise in my system when using Hydrasynth

[Telemaxis]

Hi all - hoping someone can help me here.

I am getting some background noise (not mains hum) when I play my hydrosynth through my PC (my DAW is Reaper). My audio interface is a Steinberg UR22.

I am taking a lead from the left-hand main output on the Hydrasynth into the UR22 using a standard jack (ie the one I normally use for my guitar). I am getting the same background noise, irrespective of which input socket on the UR22 I use.

When I use theHydasynth as a midi controller for my soft synths, there is no background noise at all.

As a newbie to connecting a hardware synth to my system, I'm probably doing something wrong and - whilst the background noise isn't obtrusive, I'd rather it wasn't there - obviously!

All suggestions and help will be much appreciated!

Cheers

[Wonks]

The Hydrasynth (I've only checked on the Deluxe) has balanced TRS outputs, so I'd first use a TRS to TRS cable for better noise rejection and less chance of hum.

MIDI doesn't carry any audio signals, so you won't get any hum just using that.

[Telemaxis]

Thanks Wonks - will give TRS cables a go

[Hugh Robjohns]

Definitely worthwhile switching to TRS cables to take advantage of the balanced outputs. I'd also use the standard line inputs, rather than the high-impedance DI input mode. I expect that will solve your problem.

Hums and buzzes when using unbalanced connections are most often caused by ground loops.

If practical, try to make sure everything is powered from one wall socket via a star arrangement of mains extender boards. The idea is to keep the mains earth paths as short as possible.

It's also possible to get nasty noises if you've connected the USB cable between Hydrasynth and computer, either for USB-MIDI or for patch transfers etc. In such cases, a USB opto-isolator might provide the solution.

Standard MIDI connections are opto-isolated, so there should be no problems there with ground loops.

[ajay_m]

If you have the Hydrasynth connected over USB as well as audio connections, then yes you may well get noise - I had this problem. A cheap USB1.1 optical isolator will resolve this issue and the bandwidth is fine for USB MIDI or transferring patches - but I would remove the isolator temporarily if you are doing firmware updates over USB, just in case.

[Hugh Robjohns]

I haven't used this myself, but friends have and say it works well for USB 2 High-speed (480mbps) connections... and its only £40 instead of £100+ of most other high-speed isolators.

The Analog Devices ADUM3165/3166 isolator chips seem to be the ones to look out for...

DSD TECH SH-G01B USB Isolator with High-Speed ADI ADUM3165 Chip - 480Mbps

https://amzn.eu/d/4JKnk8X

[The Elf]

I've found the Hifime isolators to be effective and reliable. No idea what technlogy is inside them, but I have a few of them and they've fixed the USB noises I've had (e.g. MicroMonstas, Typhon, Nymphes, Blofeld).

It's ridiculous that we have to do this kind of thing. Surely the problem could be designed out of these machines?

[Wonks]

Then you’d have non-standard USB ports (unless they come up with another standard). So if you plugged into a standard USB port and it didn’t work, the maker of the kit with the standard port would just shrug their shoulders and say ‘It’s not me’.

What you want is the USB equivalent of a ground lift switch.

[Hugh Robjohns]

I've found the Hifime isolators to be effective and reliable. No idea what technlogy is inside them...

I only found one one Hifime adapter, and it appears to use a 12/1.5mbps (full/low speed) isolator chip (the Analog Devices ADuM4160). This is conceptually similar, and from the same manufacturer, as the high-speed ADuM3165 chip I mentioned, but it's a lower-speed version.

The 12mbps speed limit is probably not a problem in most cases, but where you do need a high-speed connection the one I listed is a better choice — and only £10 more expensive!

It's ridiculous that we have to do this kind of thing. Surely the problem could be designed out of these machines?

It would obviously add slightly to the build (and thus retail) cost, and it's not required in many systems so would be an unnecessary cost... but certainly for 'professional' keyboards I agree something like this should be built-in as standard.

[The Elf]

Then you’d have non-standard USB ports (unless they come up with another standard). So if you plugged into a standard USB port and it didn’t work, the maker of the kit with the standard port would just shrug their shoulders and say ‘It’s not me’.

What you want is the USB equivalent of a ground lift switch.

I don't understand this. I have gear that doesn't create USB noise, and gear that does. If one manufacturer can manage it (and I get no sense of them being non-standard), then why can't they all?

[The Elf]

The 12mbps speed limit is probably not a problem in most cases, but where you do need a high-speed connection the one I listed is a better choice — and only £10 more expensive!

[Wonks]

Probably a different internal grounding system, but just guessing.

[The Elf]

Probably a different internal grounding system, but just guessing.

There's at least one manufacturer from whom I have otherwise excellent synths that declare in their product manual that they are aware of the problem, and suggest their customers buy isolators!

I'd rather they take a look at why they can't fix it themselves, yet other manufacturers can!

[Wonks]

Internal vs external power supplies?

[Hugh Robjohns]

I don't understand this. I have gear that doesn't create USB noise, and gear that does. If one manufacturer can manage it (and I get no sense of them being non-standard), then why can't they all?

Just because not all designers are equally competent, or all manufacturers equally diligent in their manufacturing, testing, or QC.

None of this stuff is easy to design, though, and effective internal grounding can be very tricky to get right...

[Arpangel]

I'd rather they take a look at why they can't fix it themselves, yet other manufacturers can!

Oh dear, another reason not to buy an eight legged beast.

[The Elf]

I'd rather they take a look at why they can't fix it themselves, yet other manufacturers can!

Oh dear, another reason not to buy an eight legged beast.

I'm certainly not referring to ASM, if that's what you're oddly referring to? No problems with either of my Hydrasynths, and no isolators needed.

I had no idea you were still needing reasons not to buy one.

[Hugh Robjohns]

he always needs justification for everything...

But just for added weight, I've had no USB noise issues with my Hydrasynth Deluxe either.

[Eddy Deegan]

I've had no USB noise issues with my Hydrasynth Deluxe either.

I had a minor (non-USB) noise issue with my Hydrasynth Deluxe but that was just Mrs. D. asking me why I bought another Hydrasynth when I had one already. Rather than try to explain or justify it I gave her my original Hydrasynth to use in her setup and that solved the issue altogether insofar as we're both now in agreement that Hydrasynths are amazing

[The Elf]

I fully intended to sell my Hydra KB once the Deluxe arrived... I really did, but...

I'm sure that those of us who have our Hydras understand.

[ajay_m]

Yes, I went through that exact same dilemma. But eventually common sense prevailed and I sold the 49 key version for a very good price to a lovely gentleman who drove all the way from Coventry down to Berkshire to collect it. So I like to think that the total happiness of the world has increased because two people are now enjoying this great synth instead of just one.
Why noise in some scenarios?. Well the likely culprit isn't the hydrasynth but the laptop. Modern CPUs consume enormous currents at low voltages and you therefore have maybe 10 amps at 1.5V or thereabouts being switched rapidly by all the various sophisticated power control circuitry and within the CPU.
This current flows to ground via multiple paths and ultimately back down the laptop power supply and there's no real "absolute ground" point within the laptop. At these kind of currents a small differential voltage can occur even between two points with a fairly low impedance path. Now connect an external device to both usb and audio and you have two ground points which are highly likely to have a non zero impedance between them. That spurious current flowing around the laptop internal circuitry then appears across them because now there's an alternate path out the usb ground and back in via the audio signal ground and then this in turn causes a small signal to be induced into the audio signal on the ground wire. While balanced I/o can mitigate this, the signal has a pretty high bandwidth with lots of RF level hash, and so the nett result is a buzz or whine.
Isolating either the audio or usb path resolves the issue because that circuit is broken. You can often find that taking a piece of chunky speaker wire and touching it to audio ground and usb ground at the laptop side also reduces or eliminates the signal because you just provided a really low impedance path for it, but this isn't usually practical and because the source impedance of the interfering signal is so low, perhaps 0.01 ohm or even less, even a stout piece of wire isn't a short circuit to that source. Recall that by ohms law 10A flowing through 0.01 ohm will drop 0.1V which is more than enough to cause trouble.

[Arpangel]

he always needs justification for everything...

These days, just for getting out of bed.

[Wonks]

he always needs justification for everything...

These days, just for getting out of bed.

And he doesn't get out of bed for less than £10k.

[Arpangel]

he always needs justification for everything...

These days, just for getting out of bed.

And he doesn't get out of bed for less than £10k.

I'm up shaved and dressed!

[ajay_m]

I purchased one of the USB2 isolators from Amazon. It worked with a USB mouse but otherwise did not work at all connected to any devices that worked perfectly with the USB1.1 isolator I already have. This included the Hydrasynth. So unfortunately I can't recommend it currently, though the older devices seem to be pretty reliable. Not sure exactly what the issue is but of course signal rates are much higher with USB2 so compatibility is probably tighter, or perhaps the unit I got has a fault, though, as I said, it did work with a USB mouse. Luckily Amazon make it easy to return items, so I'll send it back today.

EDIT: Now this is weird. In testing the new isolator I moved the HS to a USB-C port on the laptop instead of a standard USB port, using one of the nifty little adaptors I also bought on Amazon (you get a little pack of 4 that convert various flavours of USB to other flavours, including a female standard USB adaptor to USB-C male). And in moving it the noise has completely vanished. So the good news is I can repurpose the old USB1.1 adaptor for the Seqtrak, which has a terrible USB noise problem otherwise.