How to connect MIDI keyboard to a computer and get sound back in the keyboard

[ecc83]

If you can prove the laptop is quiet on battery the very best solution is to look for a power supply that does not carry mains earth through to the LT side.

Transformer isolators are all very well but can compromise audio quality (and pick up hum) and the usual dodge of dissing signal screens can introduce RFI.

Dave.

 

[SeaGtGruff]

I tested something else yesterday. I tested balanced TRS and unbalanced TS cables connected from Roland's Line Outs to the interface's audio in--direct audio signal from DP to the interface without the laptop. Balanced TRS cables did not cause any noise whereas unbalanced TS cables caused the same or similar noise.

Use balanced connections if you can, and try to keep unbalanced connections as short as possible.

 

[Celdor]

If you can prove the laptop is quiet on battery the very best solution is to look for a power supply that does not carry mains earth through to the LT side.

I proved that everything went quiet when disconnected mains from the laptop.

I am sorry but I did not follow this "a power supply that does not carry mains earth through to the LT side". If I understand, I have tried another power supply connector for the laptop that does not use mains earth (there are only two pins) but the noise was still there when I connected laptop to mains using this connector.

OMG it's so weird :/ I am just about to give up!


EDIT: Can't I just use a UPS or whatever device there is which would take the ground earth to one level and sort everything out? How engineers in recording studios cope with things like this???

 

[Celdor]

Focusrite Saffire Pro 24DSP has both a stereo headphones output on one 1/4'' TRS and 2 mono balanced Line Outs on 1/4'' TRS. The DP has only "mini" TRS stereo audio input. That means to me that from headphone to headphone I/O I carry only 2 unbalanced channels. I would probably sort the problem if I "balance" the signal. So I was thinking:
1) Can I somehow convert each channel from the interface's headphone output two unbalanced mono signals, carry it to DP but just before I would convert the two mono balanced signals to the stereo? I am a noob and this question might sound ridiculous but I am trying to find out of a device of this sort exists.
2) If I carry two mono balanced signals from the interface's Line Outs, how can I convert it to unbalanced stereo for the DP?

Thanks

 

[mjbphotos]

You can't convert unbalanced signal to balanced, and likewise if you take the balanced outputs form the line outs, and then adapt them to the stereo 1/8" input, they will be unbalanced anyway.
Your best bet is really going to be getting some decent monitor speakers rather than trying to use the Roland's built-in speakers.

 

[Celdor]

Well, technically you can convert unbalanced signal to balanced by using DI Box. Also, I know how balanced and unbalanced cables work. I was asking if there is any solution considering my quite unique problem. But, you right on buying a set of speakers.

In the meantime, I have done this: disconnected the interface from mains and left the laptop connected to mains. The noise is still there but it's significantly reduced.

Thanks.