Questions & Answers

Which Type Of Cables Do I Need To Connect Active Speakers To My Audiobox iTwo ?

0 votes
asked Mar 23, 2017 in AudioBox USB by jasonharris5 (360 points)

Hi, I'm getting some active speakers - namely Edifier R1800 BT to use as monitors for my Audiobox iTwo but I'm unsure of how to connect them to it.

I know the speakers come with a 3.5mm stereo jack to RCA connectors (the red & white type) , but looking at the Audiobox it has 2 x 1/4 inch sockets. The speakers themselves, 1 is powered, and the other 1 isn't. There's a cable connecting the speakers together so only 1 speaker is connected to the Audiobox, so I can't work out how to connect the speakers to the Audiobox, would I need a balanced TRS jack to RCA cable and only use 1 port on the Audiobox, or a 3.5mm to 1/4 inch adapter, balanced/unbalanced ? Or would I need a double ended 1/4 inch jack to RCA if they exist ? Or use the dual ended RCA cable included with the speakers and get RCA to 1/4 inch adapters ?

Also are the speaker inputs at the rear of the Audiobox iTwo balanced and for use with TRS stereo 1/4 inch jacks or unbalanced ?

I haven't got a ****** clue so please answer if you can cos the speakers are a gift for my upcoming birthday and I'd love to put them to use as monitors with my Studio One as I don't have any at the moment.

Thanks very much folks laugh

2 Answers

+1 vote
answered Mar 24, 2017 by gadget69 (31,150 points)
selected Jun 7, 2017 by AlexTinsley
Best answer
Hi, Let's see if we can clear this up. In a PINCH you could use the headphone out (with a 1/4" stereo by 3.5mm adapter) BUT the difference is that headphone out levels and impedance are WRONG... but you won't "hurt" anything (you will suffer quality of audio issues)

. So lets look at the LINE outputs of the Audiobox. When we speak of "line" level there are multiple different types that follow different impedance, and output levels. Lets start at RCA. I'm not going to get into the voltages and impedance (a combined resistance and capacitance) differences, but we will simply say that RCA is a lower voltage, higher impedance (which makes it HARD to send over long distances more than a couple feet typically) CONSUMER gear.

1/4" mono, typically used in musical instrument and pro audio, which has a higher voltage output than the RCA and a lower impedance, which allows it to drive further distances, but still has limitations. Mono 1/4" is considered single ended, (like RCA) but again, when we speak of impedance there are still BIG differences in say a guitar cable (signal) and the line level outs like the ones on the Audiobox (and other Presonus interfaces. Impedance is a VERY important consideration because if you want the sound to be the best possible, these factors have to be taken into consideration, but here we're going to just speak of 1/4" line level. The 1/4" line level outs CAN drive the RCA inputs of a powered speaker, again NOT optimally, but it will work. (Note: 1/4" line level will drive any 1/4" line level input) The difference between the 1/4" mono and 1/4" balanced/stereo is electrical level (balanced/stereo is typically higher and double ended, AND as such the signal is inside a metal shield that keeps the noise level down from spurious RF like florescent fixtures and radio transmitters, and phones.

Balanced/stereo 1/4" line level. again higher voltage (still very small as in around a volt typically) able to drive MUCH longer distances, and are basically the same as balanced XLR, and a cable with 1/4" balanced and XLR on opposite ends of a cable is essentially the same. Typically, 1/4" balanced is tip = hot plus, ring = common/negative and sleeve = shield

So, XLR balanced and 1/4" balanced are essentially the same, capable of long distances because of lower impedance, and higher voltages (again resistance to voltage flow) and the signals are encased to limit exposure to noise...Typically an XLR balanced configuration is pin 1 = shield, pin 2 = Hot or plus, pin 3 = common/negative.

Note here that typically RCA gear is considered consumer level gear.

So, get a pair of cables with 1/4" mono on one end and RCA on the other, note, converters can be used but can be problematic. The better the cable the better the sound (to a point) not necessary to get $50 cables here regardless of what the marketing department says...
0 votes
answered Mar 24, 2017 by jasonharris5 (360 points)

Thanks a lot Gadget69, much appreciated mate. yes