Hello,

I am the proud long-time owner of a Roland RD-300s full-size keyboard, a Roland Sound Canvas (SC-55MKII), and two laptop computers, one XP and the other Win7 Pro, both running the beloved PowerTracks Pro V12 (7), and a living room in which to enjoy it all in. I've just resurrected the equipment, and nothing sent from the keyboard makes it to the software or THRU to the SC-55 via the serial interface. I'm not sure that it ever did because I found an old Midiator box and another old-school interface in my box of stuff. USB/MIDI works just fine except for the humm.

PowerTracks THRU (GLOBAL) is on, and the computer can control the SC-55 and synths down the chain. There's just no MIDI IN.

I've had this equipment for a very long time and I'm aware of and have tested all of the iterations of settings (i.e.: IN1 <-> IN2, COM settings, soft THRU settings (in PT), re-installing the software & latest Roland driver, etc.), yet nothing makes it into the computer or THRU to the SC-55 from any connected keyboard using the serial interface (Roland Serial MIDI Input) on either computer. I do have other software installed on both that can send MIDI IN thru to MIDI OUT, and they both work with the USB interface, so I can't blame PT soft-THRU for not doing it's thing.

By process of elimination, I would guess that the problem is with the Roland Serial driver, or the COM port (38400 8N1 No Flow control), but I've at a standstill. I have two cables, and both are wired according to specs, so it's not the serial cable.


BTW: My setup works just perfectly with a USB interface. I can control anything I need to, and all the features of PT and MIDI work just fine. I'd be perfectly content with only that USB cable to manage, but there is HUMMMMMMMMM as soon as the plug even sees the USB port. I find myself unplugging it while I'm trying to think. All of my equipment, including my amps, are fed from conditioned power on the same circuit, and the hum doesn't change when the AC is unplugged from the laptop.

If anyone has experienced this in the past and has a suggestion to help get the serial connection to my SC-55MKII flowing both ways, I will be forever grateful. (suggestions for an acceptable USB ground loop isolator would be appreciated too. )

Thank you! Eliminating the humm will bring peace back into our world.

Thank you for entry into the forum. Click to see a very silly 9-second video of my keyboards and living room setup: RD-300s, SC-55MKII, SY77

Hi PunchDrummer,

Where exactly is that hum coming from when you plug in the USB-MIDI interface?

Also, which USB-MIDI interface are you using, and which version of Windows?

Thanks
Kent
PG Music

Hi,

With the USB connection, the hum is induced when the USB MIDI OUT is touching any of the three instrument MIDI INs. This happens with each of three different USB units, on both laptops (XP & Win7). Running the laptops on batteries doesn't prevent it.
With all units running off of a power-conditioning UPS (or not - tried it), there's not much I can do. I have a USB ground-loop adapter coming from Amazon, but for principle's sake, I really would like to get the Serial MIDI IN to work in my lifetime, and I'll most likely be be using PT soft-THRU for the duration. I'm not using Roland's UM-1. I chose a $50 USB hum-mitigator instead of taking a chance on another USB adapter. Maybe Roland's unit won't induce hum. I'm sure that if I throw enough money at it,I can reduce the hum, but I really want the Serial connection to work properly or at least know why it isn't working for IN as well as OUT. It sure is quiet (no hum).

I do change the switch in the back of the SC-55 (MIDI, RSC232..) and cycle the unit when I swap between USB and Serial. I forgot to mention that above.

Thanks for your help.

For your audio (not USB) connections, balanced connections go a long way toward reducing hum. I had hum between my little Behringer mixer and my Fast Track Pro USB interface. I was using unbalanced connectors (all I had at the time), And even though the instrument inputs (keyboard/guitar) remained unbalanced, switching to balanced between the mixer and the Fast Track completely eliminated the hum.

Hi PunchDrummer,

Is the hum coming out of the audio output of whichever synthesizer you're using?

If so, let's go over your signal chain. What are the audio outputs of the synths connected to? Are you plugging one synth at a time directly into speakers, or are they going through a mixer? Do you still hear the hum if you connect headphones directly to the synth?

What brands were those USB-MIDI interfaces?

Thanks
Kent
PG Music