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DI Boxes

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Started 1 year ago by virul3nt
Latest reply from YADE

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virul3nt

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Question / open discussion about DI Boxes here.

I'm doing a gig next month and the venue doesn't have any in-house DI Boxes, and I'm wondering if I actually need them.
I've always used DI Boxes to go from my synths / audio interface / etc to the stage box, which then goes via multicore to the FoH desk. Every venue I've ever played (in various countries and continents) has provided DI Boxes for me, or an engineer has had them on hand, so I've never had to buy my own.
The promoter of the gig knows the venue well and runs the DJ booth without DI's - he runs the signal from his DJ mixer, which has balanced XLR outs, straight to the stage-box, reportedly with no problems.

My main interface will be the MOTU Ultralite Mk3, which has balanced outputs. So if I run out of the MOTU via balanced 1/4" -> XLR cables to the stage-box, would this suffice?

Now, the other function of a DI Box (besides converting signal from 1/4" unbalanced to XLR balanced) is attenuating the signal from line-level to mic level. I'm under the assumption that the venue has the multi-core patched into the mic inputs of the FoH desk and that switching them to the line inputs is not an option.
If the levels are carefully handled, is such attenuation really necessary? Is it really worth buying a box just to attenuate a signal when I can just turn the shit down at the source?

The final factor AFAIK however is that if I have the audio interface patched directly into the stage-box without a DI, and someone hits the Phantom Power button on that channel, it could permanently damage my audio interface. Any truth to this? Oh and there's ground-lifting..not sure if that's much of a concern..?

Any thoughts would be appreciated! This whole thing has really got me thinking...
If the outcome is that DI's really are necessary, are there any discerning qualities between DI manufacturers? Is it going to shape the tone as much as, say, a preamp?
There's a low-end Behringer active 2-channel DI out there for like £15. Would this do the job? Is it reeeally worth spending several hundred for a Radial JPC stereo DI or more?

Posted 1 year ago #
Tsarik

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WILL PROBABLY PISS YOU OFF.

DI's don't just attenuate the signal. there are different impedance values for line level and instrument level signals. the DI will alter the impedance as well.

im not sure what impedance is.. or much about music. when it comes to DI boxes though... i'm sure it doesn't have to be expensive.... sure there are people out there who will pay $1,800 for a HDMI cable from Monster Cable and then spew all the propaganda they swallowed and try to convince you why your HD experience isn't as good as theirs... even though their platinum tipped Monster Cable is in reality... no better than a wire coat-hanger.

Posted 1 year ago #
KryonikMessiah23

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It's live. Just get something cheap and effective. I'd actually suggest the behringer, because if something happens to it, and because you play live, something WILL, it's easily replacable.

Posted 1 year ago #
soillodge

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It's not just about conversion. You also have to consider Ground Hum and the length the signal is being sent. Say the difference between being 10ft from the stage and being 50ft. With a passive DI hookup you can use longer cabling and not have a frequency drop out. Like loss of bass for one example that can severely effect electronic music. Also the DI reacts as a sort of buffer between the PA system and your instruments, so in being directly connected with out the DI you chance damaging your gear.

As for the cost, I tend to agree with the guys above. More expensive is not aways better, it just costs more. Overall is depends on the quality of the entire PA system. So in this instance I would go with some economy Whirlwind DI's because they get solid reviews for the price. Using Behringer is always a gamble because their reviews are scattered.

Also you want passive DI. Active is basically a preamp and is not necessary in electro music, plus it could cause unwanted distortion and smearing at higher levels. Hope this info helps out!

`michael

Posted 1 year ago #
Rogue Process

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@ Tsarik - From what scant details I remember about the subject from college, impedance in terms of audio-signals refers to how much power an amplifier/cab array or PA system needs to be fed in order to output the signal at acceptable volume. The more speakers are attached to the PA, the higher the impedance, and the more power is needed to drive them.

@Virul3nt - If somebody accidentally hit the phantom-power, it'd more than likely just clip the mixer and give you a whole nightmare fuckton of feedback howl, or if you're REALLY unlucky, fry the PA. If there were any truth to that rumour, it would most likely just be fried capacitors, which aren't that difficult to replace. That said in my experience it's always a good idea to keep critical pieces of hardware like that out the way while playing a gig. Or just gaffa-tape any dangerous knobs and buttons in place ;)

Oh, and if you're using a microphone, run it through the card rather than straight to the desk and slap a limiter and a gate plugin on the channel to minimize feedback howl, which could potentially be a lot worse than usual if your signal isn't attenuated.

I doubt with a high-quality card like the MOTU that groundhum would be an issue. I use a Firepod, that while good, are nowhere near as high-end as MOTU cards, and I've never had any issue with goundhum on the outputs.

But more to the point, the Behringer DIs are pretty serviceable little fellows. Might be wise just to invest in a couple :)

Posted 1 year ago #
virul3nt

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Great replies, thanks a lot!

I've heard conflicting things about whether Active or Passive would be better.
Some say the law of opposites - if your source is line level, use a passive DI.
Some say always use active as passive DI's take away some of the high end (comparable to the difference between using dynamic and condenser mics(!!!)).

I will be running a mic. What I was planning on doing was running the mic lead straight into the stage-box. Then, because the venue also has no FX units, I was going to bring my SE-70 and patch it into the FoH desk as a send, just for a bit of reverb + maybe delay. I could always run the mic through the MOTU first though if this would really improve the sound?

Here's the Behringer: http://www.behringer.com/EN/Products/DI20.aspx
It literally costs as much to buy this stereo DI as it does to hire 2 DI's (which presumably aren't Behringer). Which is the better route?

Posted 1 year ago #
Rogue Process

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@ Virul3nt - If the FOH and desk have no effects at all, you probably will want to run it through the MOTU - In my experience at the very least, putting a gate in the signal chain, whether in hardware or software will definitely help combat feedback. This way as well, you've got a bit of additional volume control over the mic signal.
Hope my half-assed advice has been of at least some help :D

Posted 1 year ago #
virul3nt

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@Rogue Process: yes you've been a definite help!

Perhaps the best thing in this instance is to just mix everything in-the-box. Run the mic and all synths into the MOTU and apply the MOTU's built-in EQ, dynamics and reverb on the mic. Then run out of the MOTU in stereo -> stereo DI -> stage-box.
This'll mean I'll have to tune the feedback out of the mic myself at soundcheck. I guess I'll do this using the MOTU's EQ and put a low-cut @ 200hz and then sweep some mid-bands around to tune out any spikes. Scary not to be able to rely on an engineer to tune the mic but should be possible. Any further hints on mixing live vox i-t-b?

Guess the last question really is clearing up any active vs passive confusion.

Posted 1 year ago #
soillodge

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Moar info!
http://www.gearslutz.com/board/geekslutz-forum/89637-active-vs-passive-direct-boxes.html

`michael

Posted 1 year ago #
virul3nt

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Thanks for that Soillodge!

After that I then read this: http://www.radialeng.com/di-jdi-faq.htm (which is obviously biased, but still). And some other articles online.

And after all I'm more confused than ever.

So essentially, a *cheap* Passive DI can detract from the signal too much, making it duller in the high-end, which is not so much of a problem in Active DI's.
However, Active DI's are not ideal for line-level inputs as they can amp the signal so much that it distorts.

So.....we're all doomed either way? (Maybe this is why the majority of electro gigs sound like ass hehehe)

Posted 1 year ago #
soillodge

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Yeah..heh Basically what I learned is you mess around with different systems until one works for you, then you just stick with it. Just keep in mind you are probably going to use the same set-up a DJ does because you are sending a submix and not tons of different instruments with different variables like single coil guitar pick-ups or some older analog synth machines.

So try out this Behringer solution and let us know how it turns out. Maybe that could be a nice "goto", for other musicians looking to venture out live into different venues. Also let us know how that Ultralite works out live in regards to submixing everything. From what I read, that is exactly what it is designed for and I am curious to see how it performs in our electro applications.

`michael

Posted 1 year ago #
moliere

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My experience with passives is that the more you pay, the less the degradation (better quality transformers). Cheap actives on the other hand I've never had a problem with. I got a cheap 8ch behringer DI (active) for one of my live projects (stereo backing, stereo sampler, 2x mono synths, triggered kick, triggered snare) and it does the job nice and clean and no problems (plus its got pads and ground lifts for each channel which is very versatile). No issues with line level signals at all.

I'd definitely recommend running your vox out a separate hardware out on the motu though (if you're doing your fx itb), trying to get a good mix from the stage is pretty impossible. FOH guy would normally be notching out freqs on a graphic eq attached to the monitor send anyway (to eliminate feedback), rather than on your vocal channel itself.

Posted 1 year ago #
virul3nt

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Cool thanks yeah I'll most likely do that - grab the cheap Behringer and see how it goes.
I figure the attenuation buttons will compensate for amping the signal too.
If it sounds like arse then I guess it'd be worth investing in a *not cheap* Passive (like the Radial one). This might actually not be a bad idea for future gigs anyway because most live engineers don't "understand" electro bands, so may not provide the right kind of impedence matching equipment anyway. But I'll see how the cheapie behringer goes.

I've used the Ultralite live before and I'm really happy with it (though I wasn't mixing vocals into it). I also went to a rehearsal studio where I did things like A/B the backing tracks from the Ultralite vs an iPod, and the difference was outstanding. So it's a really good unit for live laptop-based setups. It also functions in standalone and it keeps the last settings used, so if you program it with a laptop and then take the laptop away, it'll perform exactly the same. Or if the laptop crashes and the Ultralite is powered via the powerpack (not f/w), at least all the inputs and outputs will remain active, so I keep an iPod plugged into 2 of the inputs just as a backup plan in case the laptop dies mid-set.

Much MOTU love...

Posted 1 year ago #
virul3nt

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Just some more fodder for the confusion here.
I went into 2 local stores to get their opinions, both of whom had entirely opposing opinions as to what I need.
One store says I most certainly will not need a DI, since I will be going out of line-level balanced outputs into the stage-box. They say, in this instance, that a DI will do nothing beneficial as DI's generally output to line-level anyway.

The other store says I will need a DI, to convert the line-level down to mic-level. Though I'm not sure a DI will output @ mic-level(?). And the other store says it's just a matter of hitting the attenuation pad on the FoH mixer if line-in isn't available.

The first store conceded that a DI would be useful to protect the audio interface from phantom power and also to offer a ground-lift - but that is a pretty rare chance of being necessary anyway. In this instance they recommended a *not cheap* Passive, as any Active will colour the sound a little. But generally they said I shouldn't need one at all.

So.......

FFFFFFFFFFFFFFFFFFFFUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU-

Posted 1 year ago #
virul3nt

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Posted 1 year ago #
SVII-5AM

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I bring DI boxes usually because in general the PA mix is all mic level, especially if you're in a line-up with non-electro bands. I am sure you could feed the line level into the low-impedance, but it just makes sense to have all the inputs either one or the other. I know if i was a soundman, i wouldn't want to change settings for every single band and maybe when all that stuff is amped, then you become susceptible to loops and hum and possible wacky shit.
For me, there might be 2 or three mics and a line level stereo.... The only time i didn't use them was back in raves, where there were other DJs and stuff and everyone was feeding line outs...I'd hate to be booked for a gig and then find out all i needed was a couple of twenty-dollar DI boxes.

Posted 1 year ago #
YADE

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with the Setup descsribed , you don't need a DI....just check what kind of plug their Stagebox has....XLR or TRS....

and for the MIC/Line thing...even cheapest mixers offer a switch between MIC or LINE levels....

Posted 1 year ago #
soillodge

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" that a DI will do nothing beneficial as DI's generally output to line-level anyway."
I would never shop there again. Because that person apparently does not know what the purpose of a DI is. It is a conversion system for live performance standards, not just an adapter. Line level is an unbalanced signal, cannot be carried efficiently more than like 20ft and is susceptible to added noise and cross-talk issues. Mic level is balanced, you can send it 100's of ft unaltered and it is a secure grounded signal.

@YADE- I have never seen a stage box with TRS inputs. I have seen them with TRS returns, but always with XLR inputs. That is also an industry standard- to keep the cables secured [it is tough to secure a jack plug from coming out on accident] and to keep people from confusing TRS with TS instrument cables. An ungrounded instrument cable could add a lot of unwanted noise to your line signal. That is, if you overlook a DI system and were able to plug it directly into the stage box.

FYI-That switch your talking about is called a pad, it just changes the gain on the line in order to amplify a mic signal or level an instrument signal. It does not bridge impedance levels or balance a signal like a DI will do.

`michael

Posted 1 year ago #
Modulate

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There is a lot of ill informed nonsense up there which I'm not even going to get into.

If you are outputting balanced line level outputs from a sound card you shouldn't need a DI box BUT you might and it's always best to work on the worst case scenario.

You can run your line level balanced XLR signal through a stage box to the desk, should work fine, most desks can take everything from a quiet mic to a line level signal these days. Balanced line level signals (600ohm type) travel very well over distance (as compared to the higher impedance unbalanced instrument outputs from a synth which will start to suffer beyond about 10m cable length). Most nightclubs will run exactly this output from a mixer to their amp stack in another room.

Inform the sound guy of what you have though (and inform him that if he damages your kit by connecting phantom power to it that he is responsible...you have warned him). Plugging phantom power into a sound card may very well cause serious damage to it. I don't know the tech specs of your sound card but I would say more than likely...though a lot of equipment these days can handle having phantom power on the cable so do check. If in doubt, play safe. Might be worth checking the tech specs of your sound card or emailing the manufacturer on that one. A DI box will almost certainly be fine with phantom power, indeed many actually work off it.

Active vs Passive...if you are running a line level signal into it you are probably better with a passive. You only really need an active on something like a bass guitar pickup where it likes to connect to a high impedance.

If the venue has less than perfect wiring (any many do) you can end up with a ground loop...these tend to affect computers more than anything else and having a Ground Lift button on the DI is going to massively cut down the interference. Usually this will come across as 'computer noises' in the signal, a hum, noises every time you move the mouse, the hard drive does something etc. Most older laptops (or synths on wall warts) are not earthed and when you connect them to something earthed it picks up the interference.

What worries me is that a venue without DI boxes or FOH effects is also going to have a shitty mixer and almost certainly a bad sound guy. I'll put it this way, I have NEVER EVER played a show in a venue without in house DI boxes. They are standard kit. We spec them on our tech rider.

We've done about 100 shows in 10 countries over the past 3 years, everything from dives to ridiculously high specced venues. I would say about 75% of them use these specific Behringer DI boxes.

http://www.chemical-records.co.uk/sc/servlet/Info?ref=gbase&Track=DI100

They are as industry standard as you can get and unlike a lot of Behringer stuff they are actually very good pieces of kit. They work, they sound good and they are rugged as hell.

Posted 1 year ago #
YADE

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@Modulate: well I played in Holland once...and these guys had a very nice PA and the soundguy also was fit in what he was doing...but the did not have a single TRS Cable in the house...which was the only thing I forgot to put on the rider because I thought every location in the world would have it....but you are right...a venue with no DIs also for me is somehow suspicious...I mean how do they manage to make a "real" band sound then?

and I really agree to the Behringer DI...we have 8 of them in the studio for us if anyone does not provide us any....only for my Rhodes I use this baby

http://www.thomann.de/de/radial_engineering_jdv.htm

just because it has such a high impedance, that the Behringers cannot handle it without losing the velvet heights of the tone...

oh and do the Behringers really solve your Hum Problem? I often have this in 2 locations I do DJ often,...and it's always my Power supply for my Notebook.....tried everything, even ground-isolated it with a US converter...but nothing helped...will try out the DI Trick then..

oh and the MOTU can handle the 48V....maybe you would be happier if it would not ;-)

Posted 1 year ago #

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