Line6 Link And Di
Posted 04 June 2013 - 10:55 PM
The jack outputs that you have mentioned are analog and mostly unbalanced as well, so nearly all of them remain likely sources of hum, buzz, splats, spurgles, thin sound and/or distortion when connected to console inputs without the "protection" of a DI box as an interface.
(Be warned, however, that a cheap and nasty or badly configured DI is also a sure-fire way to destroy the sound from a fine instrument.)
However, outboard equipment that is "line level", such as keyboards, drum (pad) synthesizers and effects processors often (but not always) works really well when simply plugged into line level inputs, or when (almost equally simply) attenuated before being plugged into mic channels.
A good (but not infallible) way to spot gear that will work that way is its offering the option of RCA outputs.
Posted 05 June 2013 - 03:31 AM
I have plugged alot of different gear into my M20d so far and have yet to find that I needed a DI box for anything. The preamps inside M20d can accommodate a wide range of signals. Aside from keyboards and electronic drums, I have gone direct with bass guitar, acoustic guitars with peizo pickups, HD500, GR-55 guitar synth, and of course various mics (dynamic and condenser). Not everything I have plugged into it has been balanced but I haven't as of yet (fingers crossed) had any issues with noticeable noise being introduced into the signal. In fact our bass player tried to go direct from the built in DI in his new amp and we had a terribly loud ground hum. There was obviously something wrong but we wound up setting the amp aside and just plugging his bass straight into the M20d.
I'm not disputing anything that RonMarton is stating, and I'm not trying to discourage anyone from using DI boxes, I have successfully used built in DI boxes from other bass amps. I'm just saying you may not need it. I have yet to take one to any gig I have played or done sound for, I have a lot of confidence in the M20d based on my experience so far. I hope this practice doesn't bite me in the butt someday, but so far, so good.
Posted 05 June 2013 - 04:17 AM
Those are really important posts, Guys...
Apologies for not making it clearer in explaining that, in the absence of the gain-buffering, impedance matching and earth-isolation available from DI boxes, unbalanced instrument outputs do indeed "...remain likely sources of hum, buzz, splats, spurgles, thin sound and/or distortion...", but that those DI's are a solution that's really only needed in the event that you're experiencing those sorts of problems.
Your picking up my oversight is yet another example of this forum's great value.
As my gigs are mostly "one-night stands", I make sure that my pair of Samson "S-Direct Plus" DI boxes are always with me, in spite of the fact that I rely (almost exclusively) on line level, earth-independent, balanced pairs in Cat.6 wiring whenever long cable runs are required.
I've often found that the extra weight of those two tiny boxes (four full circuits) has proven to be worth its proverbial equivalent in gold, ...especially when trying to capture the full authority, timbre and transient "attack" of some "impedance-sensitive" vintage pickups.
...But don't get me started on their gig-saving (and maybe life-saving) capabilities when faced with the (gulp) "unusual" earthing and power arrangements I've encountered in the "local" halls of the Australian outback...
Posted 05 June 2013 - 04:31 AM
Oh, ...and I guess we really should mention that a Line 6 wireless beltpack direct from a pickup is (possibly) the best-ever DI eliminator...
It's also one of the few ways I know that we humans can be fully independent of the Earth.
Vive la Révolution !
Posted 05 June 2013 - 05:01 AM
I don't think there was any oversight on your part. I think it was understood that you were suggesting that the DI could alleviate those problems, should they arise. And it remains and may always remain sound advice. I think all Antoniocd and I were trying to get at was that so for in using the M20d, neither of us, to date anyway, has had the need for a DI. I have not ruled out that in the future I could run into that situation, if it happens I may well end up sorry that I don't have one handy. It may be an unfortunate circumstance that each time I use this board my confidence in it's abilities grows. It makes me wonder if line 6 hasn't designed the pre's in this board with the elimination of DI's in mind. They are storable in setups, which you don't see in many boards, so even if they are analog they must be controlled digitally, I wonder what other circutiry lies inside these amazing little beasts.
Posted 05 June 2013 - 07:01 AM
You're most kind, litesnsirens, ...but I reckon the less well-travelled among us may really need that clarification.
Speaking of experience, your comments about the easy transparency that characterise the input stages of Line 6's M20d show remarkable insight.
As far as I know, Neumann's "D" series http://www.neumann.c...kmd_description are almost the only mics that allow total bypassing of good ol' XLF inputs in favour of an AES connection that facilitates "totally digital" control and acquisition.
So those M20d inputs are indeed analog that "...must be controlled digitally...".
As for the "...other circuitry (that) lies inside these amazing little beasts...", we can take a pretty well-educated guess at the earth-independent electronic balancing that's going on, but when it comes to the rest of Line 6's proprietary trickery...
...Ah, ...er, ...um, ...can we take a rain check ?
Posted 06 June 2013 - 05:39 AM
I'm guessing you'll be fine, pierrebriend...
...Unless the guitar amp is run from a different AC mains source to the one powering your M20d. That may then cause hum and buzz.
As you say the distances are short, (and nothing is drawing much AC current) so it should be fairly easy for you to arrange power to both from the same source.
Posted 06 June 2013 - 08:08 AM
I'm using M20d + 2xL3t +2 x L2m. All that gear connected via LINE6LINK. I understood that the signal is digital. Are DI s necessary for keyboards or acoustic guitar pr any other instrument with Jack output?
DI's serve 2 major purposes. They help to mitigate losses caused by sending analog signals through cables and the serve to provide galvanic isolation between gear. Digital to digital such as in L6 link has no such problem.
So with every inch of cable from anything analog into anything else analog (a guitar or a keyboard) you will lose some high frequencies. The longer the cable the more loss. There is also the likelihood that you will have increased hum/buzz pickup. So the short answer is ... if it doesn't bother you then no action is necessary. Generally if you keep unbalanced cables under 20 feet you will probably be ok. If you have to run 100 feet then that's another matter.
If your DI's are transformer isolated then they break the direct electrical connection between pieces as the transformer accepts electric input converts it to magnetic and then back to electric. So there is some safety benefit as in you can probably eliminate 99% of any possible electric shocks. It can also come in handy if there are ground issues between pieces (like from a keyboard, drum machine or laptop) and greatly minimize buzz and hum.
So whether you choose to use them is up to you.
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