What are the pin out of the Combo Audio Port?

[NamasteFromInd]

Can anyone help me with the Pin Out of the combo audio port of a HP Laptop?

[David_J_W · Accepted solution]

I would expect it to the the "PC Headset" and "CTIA/Apple" pinout shown on this page (click). The "OMTP/Nokia" pinout has become obsolescent. The only non-standard this day are remote controls, which laptops don't support anyway (Apple has a patent protecting their remote control standard, as I understand it).

You can identify which is the microphone contact, because I would expect a small positive voltage with respect to ground, which is the bias voltage for an electret microphone.

The microphone input is pretty low fidelity. The common ground with the much higher signal level on the headphone pins typically makes it rather noisy if both the headphone outputs and the microphone are in use simultaneously.

It is much better to use a separate audio interface for any application where you care about the quality of the audio.

[Callowell]

Thanks David, I've been attempting for nearly two months to get an answer from HP Support on which type of standard is used for the Combo Port on my Spectre ...and still waiting.

I was hoping tomuse this interface to input from audio tape for digital processing. From what you say about the quality of audio input on this jack it just aint worth it (enough potential quality problems from cassette tape alone without adding to it.

[David_J_W]

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@Callowell wrote:

Thanks David, I've been attempting for nearly two months to get an answer from HP Support on which type of standard is used for the Combo Port on my Spectre ...and still waiting.

I was hoping tomuse this interface to input from audio tape for digital processing. From what you say about the quality of audio input on this jack it just aint worth it (enough potential quality problems from cassette tape alone without adding to it.

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There are so many issues to overcome if you wish to use the combo jack as an input from cassette tape. At the very least you'll need a DC blocking capacitor and an attenuator to drop your line level (or headphone level) signal down to the relatively small signal expected on the microphone input. It is a mono input in any event.

I simply would not bother with the built in audio hardware for your task, though I'm rather spoilt by having a multi channel USB audio interface from one of the top end manufacturers on my desk. You can get basic but perfectly functional external audio interfaces for relatively little that are ready to accept line level inputs and will have much better signal to noise ratio than any internal sound card. Steinberg UR22mkII is one option that comes to mind, though it isn't one I have experience with personally (you will need both input channels for a stereo cassette input). Indeed, if all you want to do is connect a cassette recorder, there are even simpler options out there.

The Steinberg interface is particularly attractive if you have any interest in Cubase, as a very cut down version called Cubase AI comes bundled with this interface. Cubase AI should give you a discounted upgrade route to any of the retail editions of Cubase if you want additional features.

[Callowell]

I believe I had foolishly misunderstood the Combo Jack connections regarding inputs.

Now, thanks to your excellent advice, will now explore USB Audio interface products.

Your help much appreciated!