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Direct boxes for synths?
Old 5 days ago
  #1
Direct boxes for synths?

I recently picked up an IK multimedia Uno Synth. It sounds great but due to being powered by USB it's ground loop buzzin like crazy when audio is plugged back into my interface instead of headphones. I can power it on batteries and it goes away even when the USB is providing the midi, but I don't want to deal with batteries all the time.

First I tried a $15 1/8 inch audio isolator thingy from amazon. Buzz gone but I swear some detail especially in the highs is gone too. It has transformers in it (I believe thats whats in the picture) and I paid almost double for the "Hifi version" with the "bigger" transformers. It looks just like the cheaper one because it doesn't have a certain sticker that was supposed to be on it even though it was in the hifi box. Theres no way to open it. I bet they ripped me off.

Now I got my hands on an ART X-Direct active DI box. The buzz is gone and it's practically noise free when I activate the ground lift on it. It sounded really good at first and I noticed all kinds of detail compared to the cheap isolator. I made recordings of all 3 ways. DI box, usb isolator, and batteries straight. What I found was batteries had the most neutral sound. Usb isolator had a compressed sound that I kind of liked with full bass, but less highs and abit of weird upper mid range. The DI box sounded great with natural highs and mids almost exactly the same (maybe a little brighter) as the no DI battery version. Problem is the bass was about say 5 db less then both the usb ISO and batteries recordings which were the same on bass. Oh and I used the same midi for all recordings.

I'm driving myself crazy here! I've used DI inputs on nice preamps before when I want saturation or an interesting tone color, but I actually don't here and they don't have the ground isolation I need anyway. I just want what the damn thing sounds like. What do you think? What do you guys do? Do you ever use DI boxes on synths? Do they all sound different than each other? Is it the impedance lowering thing that's inherent in the process changing the sound? Ik recommends making a modified audio cable as an option, but I'm just not the guy for that.
Old 5 days ago
  #2
Gear Maniac
 

Are you taking usb power from computer or wall wart?
Old 5 days ago
  #3
Quote:
Originally Posted by Ludar View Post
Are you taking usb power from computer or wall wart?
I'm taking power from the computer. It makes no noise from a usb wallwart. The Uno has no dc in jack, only usb for power. The uno synth doesn't have regular midi ins. it has 2.5 mm jacks where you need a special cable only available from IK for $20 for the in and another $20 for the out. I bought mine used and don't have those cables.

I could use the wallwart for power and regular midi if i had those cables but there's a few reason's I'd rather not and would rather use Usb. #1 I'd rather not spend $40 in extra cables to use a synth I paid just $100 for. Also though, I don't like the clutter. Midi would be 2 cables and I'd have to buy those as well. I use USB midi on most of my other synths and have no problems. They are not powered by USB though. The main reason though is the reason I got the Uno in the first place. It's an automation monster! I want to run tons of automated midi CCs to the unit while striping my audio. I don't want stepping. I feel like midi din from the 80s will be less smooth.
Old 5 days ago
  #4
Gear Maniac
You can try powered USB hub. It may help with hum and uno will be still connected by USB only.
Old 5 days ago
  #5
Quote:
Originally Posted by unicorn74 View Post
You can try powered USB hub. It may help with hum and uno will be still connected by USB only.
Thanks for the suggestion, but that is already what Im doing. i have two powered usb hubs daisy chained. There is a usb isolator between the first hub and the computer that elminates computer noise to all the synths. It works really well. If you include the Uno I have 10 synths hooked up usb to those hubs. The Uno is the only one thats a problem and not when powered by batteries. None of the other synths need usb power though. I am powering two 8 port midi interfaces off them though. All devices in the room are plugged into one outlet. My interfaces are firewire 400 and the ground is going back over the audio cable into them which is why the di box and audio isolator work. Im curious if other people use di boxes and what kind of sound differences do they notice?
Old 5 days ago
  #6
Lives for gear
 
Acid Mitch's Avatar
 

D. I. boxes are supposed to connect to a preamp.
They put out mic level instead of line level so you'll get a drop in volume when connecting to line level inputs.
Old 5 days ago
  #7
Lives for gear
 
Acid Mitch's Avatar
 

You could try a usb power supply and not connect Uno to the computer via usb.
Old 5 days ago
  #8
Quote:
Originally Posted by Acid Mitch View Post
D. I. boxes are supposed to connect to a preamp.
They put out mic level instead of line level so you'll get a drop in volume when connecting to line level inputs.
I have the DI connected to the mic in of my interface. It's an active DI and am powering it by 48v from the interface which is a Motu 828 mkii. You made me just think of something though. The DI is dropping the gain so the following mic pre can raise it. Maybe the mic pre is whats changing it. They are dual jacks. If I used the same jack (no di) but the 1/4 inch middle part there would of course be less gain because id be running line level. Running the DI im actually using the preamp and of course its gain. It does sound great using the DI mind you and Ive been playing the Uno a few hours, but it kind of kills me that I have to change the sound a little to use it. It has less bass and maybe a hair of saturation.

The reason I don't use a usb power supply, is I need the usb for midi. I don't wan't to spend $20 x 2 for the IK 2.5 mm-din cables and midi cables x 2 to use a synth I bought for $100 but that's not the only reason. The main reason is that I got the Uno because of it's full midi cc control with lots of parameters to automate. I plan on having lots of CCs heading to the Uno while recording to audio. Sending all that down a regular midi connection from the 80's will probably make more stepping or worse, mess with my note-on note-off timing.

Thank you for the suggestions.
Old 5 days ago
  #9
Your observations are correct. Basically you're hearing transformer non-linearities (it's why toob stuff sounds nice, they use well made transformers not cheap ones like your isolator). The problem buzz is caused by a ground loop, because digital electronics designers don't pay attention in analogue electronics 101 any more.
https://www.electronics-tutorials.ws...er-basics.html

For transparency better to use a transformer on the USB connection instead of the audio:

https://www.amazon.co.uk/iDefender-G...60717904&psc=1
Old 5 days ago
  #10
Quote:
Originally Posted by madtheory View Post
Your observations are correct. Basically you're hearing transformer non-linearities (it's why toob stuff sounds nice, they use well made transformers not cheap ones like your isolator). The problem buzz is caused by a ground loop, because digital electronics designers don't pay attention in analogue electronics 101 any more.
https://www.electronics-tutorials.ws...er-basics.html

For transparency better to use a transformer on the USB connection instead of the audio:

https://www.amazon.co.uk/iDefender-G...60717904&psc=1
I have something similar i think between my first hub and the computer. Before I did that I got computer data noise on most of my analog synths. Just to see what happens I tried sticking it between my hub powering the Uno and the Uno. Of course it got no power. The usb isolator is an electrical isolator and it blocks the power. Is what's in your link sommething different? Does it block the power or clean it in some way? Below is the usb isolator i tried.

The art x-direct is a probably a good di and that's why the Uno is sounding nice through it, better than the crappy line level audio isolator I got. I'd still rather not have to change the sound at all though unless I want to. For that I could bring in my Shadow Hills Gama from the other room. Once I get into that though then the Uno will sound way different from every other analog I have and i'd feel obligated to use the Shadow hills or other colored mic pres on every other synth. I'm trying to keep my complexity down and my good mic stand alone pres in my other room. I'm also not really looking for mmuch saturation in my analog synths. They're colorful enough.
Attached Thumbnails
Direct boxes for synths?-3a248d8c-be7e-4000-85f1-05b81c47fed7.jpg  
Old 5 days ago
  #11
Quote:
Originally Posted by StarfishMusic View Post
Does it block the power or clean it in some way?
It's billed as an isolator, so it should have a transformer in there to isolate the power ground, so you still get power but the loop is broken. Same thing a DI box does, but it's not in the audio path. I haven't used this actual one though.

The one you have is mis-advertised. It should keep the power flowing. This one is definitely the real deal:
https://ie.farnell.com/olimex/usb-is...HOPPING-OLIMEX
Old 5 days ago
  #12
Gear Maniac
 

I've the Uno synth and no problem at all.
Is there something wrong with the synth, have you tried another usb cable?
Maybe you can plug the Uno into another pc, maybe one of your friends to see if the problem stays the same or not?

Groundloops are not always easy to solve.
I bought a Music 10 Blackbox and had a groundloop at the moment I plugged the audio out of the Blackbox into my interface.
Never had a groundloop before with one of my other synths.
The only way I could solve this was to use it with the adapter that comes with the unit, luckily with this one it's possible to power it in two ways.
Sadly there's no other way to power the Uno.
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