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I would like to record the demo music on our Yamaha CVP 201 electronic piano, preferably by connecting it directly to a recording device's input.

Right now, I have a 3.5mm splitter to separate the L and R channels, sort of like this: enter image description here

as well as a 6.5mm to 3.5mm converter: enter image description here

I also have a long dual RCA cable: enter image description here

My stereo requires a L and R input so I use the 3.5mm splitter and the RCA cable to connect an MP3 player or computer (or other device with just one 3.5mm output) to the stereo.

The piano has a 6.5mm output so the converter is needed to plug in headphones, etc. I am thinking I could plug the 3.5mm splitter into the converter, connect the dual RCA cable to that, and somehow connect the other end of the dual RCA cable to the computer's microphone input (no line in).

According to this website, this is possible and is known as reverse wired. I would need something like this I think: https://www.amazon.com/USB-Video-Audio-Grabber-Recorder/dp/B01GSJS0V2

enter image description here

First, I would like to confirm that such a setup would even work. Secondly, this question mentioned that connecting line out to line in from the same device could damage the hardware. Since this is from one device to another, would this be safe? Or would the voltage levels coming out of the piano overwhelm the computer's microphone input? I am assuming that since the piano has a 6.5mm output, like an electronic drum kit, the voltages are pretty low since they are meant for headphones, not speakers without amps.

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    \$\begingroup\$ What are the piano output specs? What are the computer input specs? Do they match? \$\endgroup\$ – Solar Mike Jun 10 '18 at 21:09
  • \$\begingroup\$ @SolarMike I no longer have any of the documentation. There is an HP G62 laptop nearby, and the piano is a Yamaha CVP-201. The following guide I just looked up (grider.de/pdf/CVP203_catalogue.pdf) says it has a 40W X 2 amplifier/speaker system, PC interface (TO HOST), and dual headphone jacks. The G62's manual simply says " Connects an optional computer headset microphone, stereo array microphone, or monaural microphone" \$\endgroup\$ – InterLinked Jun 10 '18 at 21:13
  • \$\begingroup\$ This is, of course, unanswerable without the internal details of the consumer products in question, and as a result off-topic here, like all questions which are about the usage of consumer products rather than the design of electric circuits. It's not just a question of level, but also of ground reference - in fact, there was an era (long past, but a few classic items probably survive) when the audio ground could be at mains voltage. \$\endgroup\$ – Chris Stratton Jun 11 '18 at 0:57
  • \$\begingroup\$ If any of these is made of fine chinesium, it will go up in flames \$\endgroup\$ – PlasmaHH Jun 11 '18 at 7:16
  • \$\begingroup\$ According to the user manual, this piano has aux out in addition to the phones output. manualslib.com/manual/196681/Yamaha-Clavinova-Cvp-201.html \$\endgroup\$ – Dampmaskin Jun 11 '18 at 10:12
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In general, you won't cause any damage. A wise precaution is to turn down the volume on the instrument before plugging in and then turning the volume up until the level is adequate.

The problem is noise.

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. The typical setup.

The amplifier output of Figure 1 will send out some noise irrespective of where the volume control is set.

Now imagine that the instrument is designed to give out a 1 V signal but the PC input is 50 mV mic in. You can turn down the instrument volume control to limit the signal to 50 mV but the noise level will be unaffected. The result is that the signal to noise ratio is much worse by a factor of 20.

If the noise level is unacceptable the solution is to attenuate outside the instrument.

schematic

simulate this circuit

Figure 2. Fixed resistor attenuators or variable potentiometer attenuators.

If using the potentiometer option then buy a stereo log (audio taper) pot for best results.

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  • \$\begingroup\$ A few questions: Suppose I had a desktop available nearby (I wish I did) with a Line In option (I say desktop because I've never seen a laptop with one). I'm assuming that would tolerate a higher voltage, so the noise would be reduced, correct? Also, even with the induced noise, will the quality still at least be better than say, putting a tablet near the piano's speakers (it has speakers if nothing's plugged in) and recording? \$\endgroup\$ – InterLinked Jun 10 '18 at 22:12
  • \$\begingroup\$ Your understanding is correct. Depending on the noise levels it could sound better on mic but you risk picking up background sounds. \$\endgroup\$ – Transistor Jun 10 '18 at 22:25
  • \$\begingroup\$ And would there be less noise with line in as compared to microphone? \$\endgroup\$ – InterLinked Jun 10 '18 at 22:47
  • \$\begingroup\$ Also, is there any way to reduce or eliminate the noise, or is that just inevitable? And would it be possible, using Audacity or a similar program, to filter out the noise? \$\endgroup\$ – InterLinked Jun 10 '18 at 22:48
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    \$\begingroup\$ Computer Mic inputs tend to be rather poor quality especially for line level signals as they are really designed to interface to an electret microphone directly; I won't go into the details but it's not actually a simple voltage type input, it actually expects a small current and, well... not very good for a line input at all. I would seriously consider a USB to line converter. I've got (for instance) a Behringer model that was cheap and cheerful for these kinds of situations. \$\endgroup\$ – Ian Bland Jun 11 '18 at 0:03

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