Level 2

304 points

How to record a landline phone-to-phone conversation using a MacBook's audio-in port?

I need to record a phone conversation -- that will take place between two landlines.

(I have the other person's permission -- I'm interviewing them for a paper and we both want a permanent audio recording of the conversation so that the quotes can be later double-checked for accuracy. So, the legality question is not the issue.)

I could do it the old-old-old-fashioned analogue way of getting one of those 1960's-style microphone pickups that have a suction cup to put on the phone...but the audio quality of that is probably pretty low.

I'd much prefer doing it directly digitally by having the phone's audio signal go into my MacBook Pro's "audio in" port and then recording the whole thing with an application on my Mac.

I've solved various peripheral aspects of the problem already: I have a choice of at least three different applications that can make recordings of the internal audio signal on the Mac (among those applications are Amadeus and QuickTime Player 7). And I have a "portable handset" connected to the landline, and the handset has a small audio-out/in jack into which a headphone headset can be plugged. And I have a converter plug which converts a "larger" (I thinks it's 3.5mm) computer-style audio jack into a "smaller" (I think it's 2.5mm) phone-style audio jack.

My questions are: Can I just use any available random 3.5mm-to-3.5mm male-to-male audio cable (such as those that connect tabletop computer-speakers), place the converter plug on one end and insert it into the phone, and then plug the other end into the MacBook Pro's "audio-in" port?

What would happen if I tried that?

Or do I need some kind of specialty cables, or specialty plug-converters?

My MacBook Pro is from about 5 years ago and has one of those "audio-in" (also sometimes referred to as "audio line-in") ports that depict above them a symbol that looks like a circle with two triangles overlapping it (clear image of what the port's symbol looks like here: http://www.kozco.com/tech/audacity/pix/MacLineIn.jpg).

Or do I have the wrong hardware/port to achieve this? If so: What steps can I take to make a digital recording of a landline phone call successfully?

Presumably, even if this scenario I sketch out above is feasible, since the audio out-signal from the phone is being redirected to the phone's out-port, I will not be able to hear the person on the other end from the phone's ear-piece itself; instead, I'd have to speak into the phone's mouthpiece but to hear the other person I must turn on the computer's volume and listen to the audio coming out of the Mac's built-in speakers. A little awkward, but doable.

Or am I barking completely up the wrong tree? If so -- what is the right tree? I'd like to do this without buying more hardware or specialty cables, if possible.

MacBook Pro, Mac OS X (10.6.8)

Posted on May 27, 2014 3:49 AM

20 replies

Tuffy Nicolas Author

Level 2

304 points

May 27, 2014 11:41 AM in response to Csound1

The existing converter plug I was able to purchase (a while ago) for 59¢. That's the level of expenditure I prefer to make. The store where I bought it is a pretty well-stocked independent electronics store, and the next time I get over there (it's not particularly near where I live) I'll ask about cables that are pre-manufactured to be 3.5mm-2.5mm, with two channels at boths ends, and buy that, as you suggest. If they don't have that, I'll ask about a 3.5mm-2.5mm converter plug with two channels, as opposed to the one-channel converter I currently own. (Maybe I'll get both the cable and the converter, if they have both and if they're cheap, just to have a backup.)

I'll report back in the distant future (i.e. not today) when and if I am able to get the necessary "bendware" (is there a better name for the category of "flexible cables"?).

The whole point is that I (and everyone here) own a beautiful complex computer that has the capability of creating pro-quality audio recordings -- if only there was a way to get the signal into the computer. Apple has spent so much energy making Macs audio-friendly (i.e. they market Macs to musicians and sound engineers), that it seems absolutely absurd to have to go out and buy some offbeat third-party audio-recording device just to acheive a goal that in theory should be effortlessly do-able with just a single simple cable connecting to this world-class audio recording and editing machine known as a MacBook Pro.

Csound1

Level 9

60,063 points

May 27, 2014 12:06 PM in response to Tuffy Nicolas

Tuffy Nicolas wrote:

The whole point is that I (and everyone here) own a beautiful complex computer that has the capability of creating pro-quality audio recordings -- if only there was a way to get the signal into the computer.

But there is, in fact are several ways (analogue/digital via 3.5mm jack or usb) Anything from 1ch to 7 or 8ch, and many more than that via USB, How many is enough?

Network 23

Level 6

12,351 points

May 27, 2014 3:00 PM in response to Tuffy Nicolas

Tuffy Nicolas wrote:

The whole point is that I (and everyone here) own a beautiful complex computer that has the capability of creating pro-quality audio recordings -- if only there was a way to get the signal into the computer. Apple has spent so much energy making Macs audio-friendly (i.e. they market Macs to musicians and sound engineers), that it seems absolutely absurd to have to go out and buy some offbeat third-party audio-recording device just to acheive a goal that in theory should be effortlessly do-able with just a single simple cable connecting to this world-class audio recording and editing machine known as a MacBook Pro.

The way Apple has it set up is not necessarily inconsistent with pro audio use.

First, pro audio people would build the whole signal path around a line level signal, which the Mac happily takes. That's why they call it Line In instead of just Audio In.

Second, some pro audio people would not be interested in any form of analog audio in because they would prefer to use a digital audio in like optical or USB. This is to minimize noise.

So a lot of pros would not find the current audio in port limiting, within the context of the gear they would prefer to use at the level they are operating at.

The real problem is that a telephone handset adapter doesn't really qualify as pro audio in several ways. That's not your fault, but it's also not true that the MacBook Pro is unfit for pro audio. The real problem is that the telephone cable converter is not pro audio. It is the weak link in the chain, not the MacBook Pro.

Csound1

Level 9

60,063 points

May 28, 2014 2:54 AM in response to Network 23

Network 23 wrote:

Tuffy Nicolas wrote:

The whole point is that I (and everyone here) own a beautiful complex computer that has the capability of creating pro-quality audio recordings -- if only there was a way to get the signal into the computer. Apple has spent so much energy making Macs audio-friendly (i.e. they market Macs to musicians and sound engineers), that it seems absolutely absurd to have to go out and buy some offbeat third-party audio-recording device just to acheive a goal that in theory should be effortlessly do-able with just a single simple cable connecting to this world-class audio recording and editing machine known as a MacBook Pro.

The way Apple has it set up is not necessarily inconsistent with pro audio use.

First, pro audio people would build the whole signal path around a line level signal, which the Mac happily takes. That's why they call it Line In instead of just Audio In.

Rather unlikely really, pro audio travels on pro connectors, not on undersized consumer plugs (2.5 and 3.5mm) and is generally a balanced line rather than an unbalanced one.

USB interfaces allow for proper cabling, Macs don't (but no computers do). An XLR connector is bigger than the height of a Macbook Pro.

Compromise rules here, (and I for one am very happy that Apple took the line in off of the new Macs), that's one less compromise.

Tuffy Nicolas Author

Level 2

304 points

Jun 16, 2014 12:18 AM in response to Tuffy Nicolas

OK, just a final follow-up for those who may find this thread in the future.

I was eventually able to solve the issue by tracking down a converter plug that has a female end that accepts a 3.5mm audio cable and then has a male 2.5mm end WITH A MICROPHONE PICKUP BAND. I found this simple little converter in a bin of miscellaneous old parts at a used computer store, for 50¢, but for the purposes of this thread unearthed an equivalent device for sale online here:

2.5 mm to 3.5 mm Audio Cable Adapter - Male to Female

This Audio Cable Adapter features one 2.5mm audio male connector and one 3.5mm audio female connector, providing a cost-effective way to connect standard 3.5mm headphones to a cell phone or PDA audio port.

But what I used it for is I took a 3.5mm-to-3.5mm standard Mac-style audio cable, stuck one end into the Mac "audio in" port, the other end into the converter, and then stuck the converter into my landline portable handset's audio jack (which only accepts 2.5mm plugs), and then after ensuring that the System and recording app's settings are set to "Audio Line-in port" (as described above in this thread), simply make the call and start the recording. It worked! Unlike my earlier attempts with a similar plug -- because that original converter plug I used only had two "bands" on it, whereas this new one has three. To be frank, I'm not sure if this new three-band converter plug has a "stereo" band or a "microphone" band, but whichever it is, it managed to do the trick! The conversation (particular the party on the other end, which is the key aspect for me anyway) is recorded with perfect audio fidelity. (I will note that it is recorded in mono, but that's not an issue for me, and I can easily convert it to both sides/stereo using Amadeus.)

Anyway, eventually the problem was indeed solved, and all it took was finding the right plug! Although I will say that finding that plug was NOT EASY, as all normal retail stores did not have it in stock, and I only found a used one by chance.

Anyway, mark this issue SOLVED, and for anyone else trying to do this, look for a converter plug with THREE silver bands (i.e.with two black/blue divider stripes, dividing the male plug end into three sections).

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How to record a landline phone-to-phone conversation using a MacBook's audio-in port?