My CT-X9000in line out recording problem

[RajCha]

Hi there,

When trying to record through both TS unbalanced to 3.5mm and  headphone out cable to my computer line in port,  i am hearing a huge noise. I would like to use my CTX as a studio monitor as well! So I am using its line in as pc output. Computer's micin is working well, but I have to keep the micin's level at 2%. Is there any way to use linein of my computer? Please help!

[- T -]

I suspect that you are getting a ground loop hum.  With the old transformer power supplies, the big old heavy "bricks", this was not much of a problem, as neither the power bus nor the ground bus of the powered device was tied directly to either side of the incoming power mains, but with the modern "switching" power supplies, the ground bus of the powered device is always tied directly to the ground lead of the incoming power mains for polarized plugs or either side of the incoming mains for non-polarized plugs.  With that in mind, if your CT-X9000 power adapter has a non-polarized plug, try reversing the connection to the mains to see if that resolves your problem, if it does, then you are in business, but if it does not, or you have a polarized plug, then you will need to resort to more drastic measures.  In your case, if either the computer or the keyboard has an old transformer power supply, then you usually will not have a problem, but when both have switching power supplies, you can get hum producing ground loops throught all of the circuits.  I could suggest you try a USB MIDI/audio interface, but USB devices are often the source of ground loops, so I will not suggest that sort of investment.  Normally, before making any sort of investment, I would suggest disconnecting the keyboard from its power adapter and running it on battery.  If that resolves the problem, then you are on the right track, but if it does not, then you have a different problem and need to seek a different solution.  However, you do not have the option of running the CT-X9000IN on batteries, so you have a financial decision to make.  The only true solution is an isolation transformer between the power mains and the CT-X9000's power adapter to break that ground loop connection between the keyboard's power supply and the computer's power supply, but isolation transformers can get a bit expensive.  Sometimes a device called a DI Box can help, but it needs to be one that is designed specifically to include ground loop hum reduction, among its other capabilities.  DI Boxes can also get a bit expensive, especially those that reduce ground hum.  Perhaps the best move for now is to give this thread a few days to attract comments and suggestion from other members, who have already had success with a more economical solution.  In the meantime, you may want to do a search on "fixing switching power supply ground loop hum" for suggestions.

 

Good luck!

 

- T -

 

[RajCha]

Thankyou for the detailed and immediate reply! I am thinking about buying an usb audio interface! I will also consider your suggestions! For now, I am going to use my computer's Microphone input to record! This thread may help others having the same problem! For them, I am suggesting to use microphone input of pc with level adjustments as low as possible in the OS! Also, use low latency settings in your DAW or recording software!

[RajCha]

Also, is there a difference between recording from CTX's phones output and two TS stereo outputs?

[- T -]

15 hours ago, RajCha said:

Also, is there a difference between recording from CTX's phones output and two TS stereo outputs?

 

Yes !

 

Technically, there is no INPUT that comes anywhere near matching the impedance (dynamic reactive resistance) of a headphones output.  Maximum audio power transfer only occurs when the output impedance of the source circuit matches the input impedance of the subsequent circuit.  Also, there can be an enormous difference in level, because you are usually second-guessing on the output level of the headphones output circuit.

 

By their design, there will normally be a very close level and impedance match on Line Level outputs and inputs - such as the 1/4" (TS) L and R outputs on a keyboard and the L and R inputs on an amplifier, mixer, recorder, etc.  This is the ultimate for a good quality recording.

 

Typically, about the only device that matches the level and impedance of a MIC input is the proper type of MIC, itself.  The typical MIC input does not come anywhere near matching the level or impedance of a headphones output or a Line Level output.

 

In reality, you can connect just about any output to just about any input and get it to work, after a fashion, but it is the quality of the resulting signal that defines the success of the connection.  Level mismatches can result in signals that are low and noisy or full of distortion from an overdriven input, while impedance mismatches can result in high or low (or both) frequencies that are overly attenuated.

 

- T -

 

[Jokeyman123]

The problems I run across when recording into computers or from keyboards are primarily 2-given the reasons described by T, but certainly doesn't prevent one from recording from either output.

 

1) Depending upon the quality of recording you require-the headphone output can very easily "overdrive" the line inputs of  most recording or amplifying/mixing devices, so my volume settings usually need to be set rather low in order to not distort. This generally is less likely to happen if your output (line level) is more closely matched to your recording or monitoring input which it will be if you use a line input rather than a microphone input. And some computers have a 1/8" stereo input jack that will detect whether you are using a line-level source or microphone-my Motion tablets can do this, although I don't think this is typical. And now I see many new laptops that have no input jack at all for recording anything.

 

2) if your inputs and outputs are mismatched-such as using a headphone output to  a line-level input-or the other way around-line level out to  mic in, I definitely always notice a decrease in sensitivity-leading to frequency loss, most noticeable in the high frequencies but also throughout the frequency range. Again, if you aren't being too fussy about the quality of the sound, you can connect like this, but why go to that trouble if it will compromise your sound.  And its not doing the electronic components much good either-if driven to extreme levels you might degrade components in the signal path over time if you are using mis-matched in and outs.

[RajCha]

Thank you both of you! You both are technically very sound!

[- T -]

6 hours ago, Jokeyman123 said:

now I see many new laptops that have no input jack at all for recording anything.

 

Take a closer look, Johnathon.  You will probably find a thin, flat connector with 18 or 24 pins.  This is a USB-C connector.  I say 18 or 24, because there seems to be a big discrepancy about this on the web.  Whichever: it takes the place of the old USB connectors as well as the 3.5mm MIC/Line-In and Phones/Line-Out jacks.  Of course, these manufacturers will be more than ecstatic to sell you their overpriced adapters in order for you to connect THEIR new technology to YOUR real world ! ! !

 

- T -

 

[Jokeyman123]

Thanks for telling me this-yet another USB connector, just what I needed! I will take another look, the laptops are both Thinkpads-a T520 and an 140ex. If these can be used as audio inputs, would be nice. Lenovo makes odd-off dongles for all sorts of Thinkpad specific connectors. I know, I have 1-2 and I completely forgot what they were for in the first place, and don't fit anything anymore, even newer Thinkpads, sigh.... 

[DaveT]

My CTX5000 has only signal for Left lineout, and no signal at R lineout.

 

They are connected to the same mixer inputs.

 

Thanks for tour attention

 

 

Dave

[Brad Saucier]

9 minutes ago, DaveT said:

My CTX5000 has only signal for Left lineout, and no signal at R lineout.

 

They are connected to the same mixer inputs.

 

Thanks for tour attention

 

 

Dave

 

I would check your cable first.  Swap the left and right.