Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards unbalanced lineout to balanced xlr speaker in?

Sorry for the rather specific and spam-like question, I'm about to place an order for my first pair of monitor speakers and was wondering what cables to get.
I have a kawai mp7se digital piano with 1/4 unbalanced lineout. The speakers have both balanced xlr in and unbalanced rca in.
I'm planning to connect the mp7se straight to the monitor speakers and I'm leaning towards getting balanced 1/4 to xlr 3m cables as they're easier to find than rca cables.
Basically I would be running an unbalanced signal through balanced cables and monitor inputs. Would you foresee any problem?
Also This is for a permanent setup where the speaker is never than 2-3m away from the source of the sound.

Many thanks

It's hard to find RCA cables? They're as common as dirt.
Check Amazon.
Check Parts Express.
Google for audio cables.

It's also the fact that I could use the rca inputs for another source ( to run non-concurrently). Anyway I was more curious about the implications of running an unbalanced signal through balanced cables (1/4) and monitor speaker input (xlr).

Here is a good guide that gets you started...

http://www.rane.com/note110.html

Can anyone say whether it's OK to use a balanced jack to XLR cable (ie one with tip, ring and sleeve jack at one end and XLR at the other) for a system where you've got an unbalanced sound source (eg a digital piano) output at one end and a balanced input into an amplified speaker at the other. Or do you need to modify the jack plug in some way or put a transformer in line?

I've been reading a lot today about balanced signals etc, and it's a bit confusing.
All I would love to find out, similarly to toddy's comment, except that i would be plugging the digital piano straight to the active speaker monitors rather than an amp,
is whether it would work without any side effects

Yes, that's what I meant. Balanced inputs (XLR, jack or both) is normal (though not universal) on active monitor speakers. Not sure about hi-fi power amplifiers.....it's a long while since I've dealt with those

Yes, you can run unbalanced into a balanced input using balanced or unbalanced cables. All you would be doing is effectively connecting one of the balanced signal wires to ground. The input circuitry doesn’t care, and your lines are to short to introduce relevant ambient noise into the signal.

You don't come 'ere for the simple life . . . . . . (emoji; wall appears, head bangs repeatedly against it)

Thank you so much for this. It's one of those things I'm always unsure about. Fortunately, I'm going from balanced preamps to balanced active speakers at the moment. But I'll cut out and keep your post. Maybe stick it on the fridge.

This statement may, or may not, be accurate in the case of unbalanced OUT to balanced IN.

The Balanced IN feeds a differential amplifier. This means that balanced signal is fed, one side to the non-inverting input and the other side to the inverting input. The GROUND is used as the center reference point for both the positive and negative excursions of the signal.

If you feed an unbalanced IN to the differential amp, the non-inverting input gets the signal and the inverting input gets the GROUND, which is now referenced against the differential amplifier’s GROUND. This may be OK, as long as the two pieces of equipment do not share a GROUND. If they do, any ground loop hum and noise in the ground line will be fed to the amp.

The best way to solve this issue is to not do it. Buy an RCA cable. The other way is to use a BALUN, which is short for Balanced/Unbalanced. I wind them myself for radio work. I wouldn’t reccomend winding them yourself for audio - too much wire.

The other issue is one of a 6dB difference in signal level.

thank you very much, so essentially It's worth playing it safe, in my case, and buy 1/4 to rca cables.

cheers

For very long cable runs, XLR is best, but for a few meters, RCA is great.

Oh I see. Well I'd better make a copy of this information and stick that on the fridge too. Thank you, prout.

The audio equivalent to an RF balun is called a "DI box". It's a transformer, (and I won't go any further into never-never land!) .

Most of the common ones (any music store) are set up for matching a guitar pickup to a low-impedance microphone preamp. That won't work for you.

What you need (if you go that route) is two "1:1 DI boxes" -- which change an unbalanced line-level signal to a balanced line-level signal. One for the left channel, one for the right, unless you can find a pair, packaged in one box.

I agree with Prout -- buy cables with RCA (unbalanced) plugs, and use the unbalanced RCA inputs of the monitors. Cheaper by far, and unlikely to cause trouble.

On a short range and if DP and monitors are on the same outlet, I see no problem in using a TRS to XLR cable. In fact, it is the setup I have here, connecting my RD2000's unbalanced outs to the Eris 5's with no issues. Sometimes the AG06 goes between them, again without any issue.

As I mentioned, it may not be an issue. But, why choose do to so, unless there is no other option?

For fun, I made up a pair of 1/2 meter RCA to XLR cables for a pre-amp out to separate amps. It worked fine after adjusting the level to compensate for the 6dB loss in signal. But, then I switched back to the RCA pre-amp OUT to RCA amp IN and it worked just as well. An FFT analysis showed no difference. Now, if I had XLR pre-amp OUTs, it would have been a different story.

I should mention that when converting from XLR to RCA not using a BALUN, you are losing Common Mode Rejection, which is why XLR is used in the first place.

If you have both RCA IN and OUT availabie on your devices, it would be silly to use XLR for short runs. RCA OUT may, or may not be at LINE-LEVEL.

If you have both XLR IN and OUT avaialble on your devices, it would make sense to use XLR in order to maintain LINE LEVEL signals.

Keeping everything at LINE-LEVEL makes setting recording levels SO MUCH EASIER. You have a common frame of reference instead of farting around with - ‘maybe it’s Consumer Line Level’, and, even worse, probably being screwed by a variable output level.

The other thing is the 6dB signal level change. The RCA OUT is -6dB relative to the XLR signal, so you need 6db more gain to reach the same volume level, meaning a 6dB increase in background noise level, or 4 times the noise level.

Just sayin’.

For the short cable runs you’re talking about, I would bet that none of this makes any difference whatsoever. Are you sure the monitors you’re looking at would have XLR jacks and not combi jacks that would accept XLR or 1/4” plugs? Your MP7SE has L and R mono outs, so I’d use TS (not TRS) 1/4” cables to either 1/4” or XLR at the monitor side, and not think much more about it.

Before you buy XLR to RCA jacks, you must first confirm the pinout... cables and pinouts will vary. Check your owner's manual on your keyboard or whatever device you are trying to connect with. On most equipment, Pin 2 of the XLR is HOT and should connect to the center pin (or hole) of of the RCA jack. Most likely this is the case, but you have to confirm as there are different cable configurations to accommodate different equipment. Usually Pins 1 and 3 of the XLR will be connected together and connect to the "ring" of the RCA jack. Good cables will tell you what they did in the spec.

Said again, make sure you equipment shows Pin 2 as hot and the cables you buy show Pin 2 going to the center post (or hole) of the RCA jack.

Peace
Bruce in Philly