Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards Casiogp400 + vst + USB + Audio cable = buzz

I'm just getting started with VSTs for my casio gp400. The problem I've been having is with buzzing when playing through the gp400 speakers. (Sorry if following is long but want to isolate the issue).


Here's the situation: I'm using pianoteq (demo) or sforzando on an i7 Lenovo laptop. The gp400 is connected via a USB cable. If I connect my headphones to the laptop the sound is nice, no artifacts such as cackling, hissing..... life is good. (Though perhaps the laptop sound is a bit underpowered). The problems are when I plug in cables from the 3.5 mm laptop jack to the .25" inputs on the gp400. There's a constant hiss, there are quick little beeps (similar but less pronounced than old school ) and there are occasional cracks/distortion which is definitely NOT occurring if I don't use the gp400 speakers.

A few more things: (1) whether I utilize the USB port (on the laptop) close to or far away from the headphone jack makes no difference (2) whether the laptop is running on battery or plugged into outlet makes no difference. (3) making sure that the cables are not physically looped or crossing makes no difference. (4) If the midi cable is not connected to the laptop, and I run the computer audio (eg demo of pianoteq sounds) through the gp400 inputs, no noise or hiss occurs. (5) using different audio cable didn't change anything. Neither did using a different printer cable. (6) As a troubleshooting step I hooked up the USB cable to one computer and the audio cable to a different computer. (one was Lenovo, one was mac). Of course this isn't a functional setup. In any case, if the usb cable and the audio cables are both in use, both plugged into the gp400, but connected to different computers, the hiss isn't present.

So I think that the noise is due to the simultaneous use of (a) usb midi output to laptop and (b) audio cable output from that same laptop (c) both cables are going to gp400.. (if i use headphones plugged into the laptop, it fixes the issue).... which is necessary to utilize the on board speakers (unless midi cables to usb would be better somehow?) Clearly it's only when there is a loop between the audio cable, usb cable, laptop and gp400. HOW CAN I AVOID THIS?

PS unrelated to the hiss, it seems that I need to limit the output from the laptop to avoid distortion with high volumes on the computer speakers.

I get the exact same problem with a macbook pro and my NV-10. One thing I noticed was the hiss would modulate if I was touching the laptop body or the trackpad, proving that the electrical noise was being generated at the laptop. It's still a ground loop, and you're right that it's caused by having both USB and 3.5mm audio connected between the same two devices.

Here are a few things to try:

1. If you don't mind added latency and your DP supports BT MIDI, you can get rid of the USB cable and the ground loop that way.

2. I found that an iDefender got rid of about 70-80% of the hissing. Not perfect, but better.

3. If you get an external USB audio interface, you can break the loop (and possibly lower your USB latency further). Unfortunate as it's extra cost/wires/hassle, but probably the best no-compromise choice.

I sounds (pun intended) like a ground loop. Even if the laptop is not connected to mains, you still have two different points of connection between it the the piano that must be causing the noise you described.

I would suggest one of these:





Get Roland, Yamaha, M-Audio or other decent brand, not one of these cheap chinese unbranded ones. I suppose and expect a good quality interface to have the isolation required by the MIDI specification that will avoid the ground loop and, hopefully, eliminate the noise.

^ This.

I have even read worse : some bit flips which transform a note-off by a control change or something like this !

Then using unbranded adaptor can be like betting with the lottery, you can win... or loose money (ok, just $5) and time.

Yes a compliant MIDI interface has opto isolators. But I had ground loops with my M-Audio. The barrel of the connector is linked to both grounds (My piano and the PC). I manage to get rid of it by plugging the connector half way (the barrel is no longer connected, but the pins are. I have to admit that the MIDI specifications are not clear about which part (cable / MIDI IN) should be connected to the barrel. The precision is quite recent ((CA-033) MIDI 1.0 Electrical Specification Update [2014] — yes 2014 !!) and my M-Audio adaptor is not compliant.

i also have some hum (not much) when I use a USB cable for MIDI.

. . . It disappears when I use the M-Audio MIDI adapter that's pictured above.

You might try unplugging the laptop's power supply -- easy to do.

You might try getting one or two clip-on ferrite cores, and clipping them around the MIDI-over-USB cable. (I haven't tried that, but it helps in some other "noise problem" scenarios).

Some people have reported success with clipping the ground pin on the MIDI-to-USB cable, or buying such a cable. (I haven't tried that, either).

I've tried it all, ferrites didn't help, clipping the USB ground wire didn't either. The 5-pin midi-to-usb adapters are a good idea, I might give those a shot.

Link? (Not trying to be lazy, but I just don't know What the name of those items are So that I can locate and price them).....

Thanks for all the input. I had already ordered ferrite cores, they should arrive tomorrow, though I'm not that hopeful. I don't want to increase latency (depending on degree of latency, it may make me give up on the idea of vst other than with headphones). But if those cables are the only way to definitely solve, sounds good. (I can't tolerate even a small amount of buzz. I'm not HORRIBLY disappointed with builtin piano sounds, but I want more choices and presumably more realism.... (and more than just 5 volume levels, which gets to the realism)..... in any case, if I hear ANY hiss, there goes the realism......

Clipping the ground clip sounds interesting (and simple??).... would that create any equipment risk (other than the 'risk' of ruining a perfectly good $10 cable) ???

This sort of thing will help with the audio connection:

https://www.amazon.com/Mpow-Ground-Isolator-Stereo-System/dp/B019393MV2/

Just an audio-frequency transformer in a box.

The ferrites can't help, the hum you're hearing is too low frequency. That'd be more for trying to keep a cable from radiating noise into other things.

As far as a USB isolation widget, I'd trust Adafruit, as they're actual electrical engineers, rather than folks trying to scam audiophiles, like everyone selling audio products:

https://www.amazon.com/Adafruit-USB-Isolator-Isolated-ADA2107/dp/B01GQFVB32/

Cutting the ground wire on a USB connection isn't going to suffice, or do anything good. Don't do that.

Roland UM-ONE MK2

https://www.amazon.com/Roland-UM-ONE-MK2-MIDI-Cable/dp/B00967UN50

Yamaha UX-16
https://www.amazon.com/Yamahaa-UX-16-Yamaha-Usb-midi-Interface/dp/B00008BCXY

M-Audio Uno

https://www.amazon.com/M-Audio-UNO/dp/B00007JRBM

This one looks OK too:

https://www.amazon.com/iConnectivity-mio-1-out-MIDI-Interface/dp/B00CO5IRSG/

I borrowed the Roland um one device from a friend who gigs.... so far no luck getting it to work..... seems like pianoteq recognizes the keyboard input but isn't outputting sound back to the piano......

I take it you mean that when you press keys on the piano, Pianoteq recognizes the input? That's all the MIDI adapter will do, it won't output sound back into the instrument. You'll need to a separate cable from your PC's audio output to the DP's audio input (and if you already have that set up and it's still not working, it's not because of the MIDI adapter if PTQ is receiving the input and rendering it; the problem is further up the audio processing chain)

Thanks for the input. I plugged in the line in cable, it had no effect (ie no sound). Aside from that, I'm not sure I understand. The um one by Roland plugs into midi in and midi out..... shouldn't that be enough? But in any case, even with audio cables, I get no audio from the piano......help?!?!

I changed the audio device type to windows audio low latency.... and it works. Kind of. There is a huge amount of hissing, though interestingly it is no longer constant as it was before (ie before it was noisy whether or not I was playing) Now it is noisy starting with the moment that the tone associated with pressing a key starts, and the hissing fades away and stops about 8 seconds after I let go of the key. In otherwords, with the printer cable, there was constant noise. With Roland um one, the noise is gentler and is associated with sound output. (Its also there for any audio output from the computer to the piano, eg playing a music file).....