to DI or not to DI

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to DI or not to DI

Postby Luka » Mon Jul 13, 2009 11:25 pm

continuing on from conversations on another forum
thought i would ask the pros

do i need to run my modular through a DI ?
i dont see why since the signals are hot anyway
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Postby heathen » Tue Jul 14, 2009 7:49 am

DI's are used to match instrument level output (bass and guits) to mic level input.

You don't really need a di for anything which sends a line level output if you are recording from line inputs, unless you want to interface the instrument with a nice mic preamp.
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Postby Thirteen » Tue Jul 14, 2009 9:10 am

Or if you are getting hum and want to lift the ground....
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Postby jkhuri44 » Tue Jul 14, 2009 10:52 am

from my understanding, if you wanted to employ the colour of a perticular preamp's sound...u ruin it through a DI only to have its gain boosted again by that said preamp.

i assume though, something similar could be achieved through compression via analog geeer.
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Postby Chris H » Tue Jul 14, 2009 11:19 am

The di is needed for longer cable runs, eg stage to foh mix or live room to control room, patch bay etc, where the unbalanced phono cable would lose signal quality. So if you are using short cable runs then no Di is needed. Of course if you have nice old valve di's with juicy transformers they might be the ants pants for a subtle change in the sound through transformer saturation or driving the valves hard.
And Heathen, i think it's line level not mic level though with a pad engaged on the di and the mic level wound down with a lower signal in , mic level would work ok but here my knowledge is limited (rob would know) depending on the pre amps design, impedance might be miss matched so the sound may be affected.
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Postby Chris H » Tue Jul 14, 2009 11:28 am

Chris H wrote:The di is needed for longer cable runs for hi z guitar and bass, and keyboards that are line level out but unbalanced. eg stage to foh mix or live room to control room, patch bay etc, where the unbalanced phono cable would lose signal quality. So if you are using short cable runs then no Di is needed. For guitars Hi-z then a hi z input like on some a to d converters or Amek dual mic pre's are great, otherwise di them. Of course if you have nice old valve di's with juicy transformers they might be the ants pants for a subtle change in the sound of your "modular" through transformer saturation or driving the valves hard.
And Heathen, i think it's line level not mic level though with a pad engaged on the di and the mic level wound down with a lower signal in , mic level would work ok but here my knowledge is limited (rob would know) depending on the pre amps design, impedance might be miss matched so the sound may be affected.
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Postby rob » Tue Jul 14, 2009 11:56 am

umm... whats a modular?

If it is a synth...then it is fair to assume that it is capable of driving medium impedances and therefore if the level is sufficient and you have the correct cabling there is no reason not to run it straight into your.....console, converters, line level outboard.

there are always three things to consider and each of them is not necessarily related
impedance...you want the output impedance of the source to be lower than the input impedance of the recieving unit. Usually in the order of 10 times lower is best. but note that this is a simplification and ignores the old school practice of impedance matching .... keep it simple ...

level... mic level, instrument level, line level...these are broad overlapping catagories.... I've seen mics spitting out line level, a hot condensor mic on a screaming marshall stack

balanced / unbalanced...should be no problems connecting an unbalanced output into a balanced input...if the wiring is correct. There are sometimes problems connecting balanced outputs into unbalanced inputs...these days manufacturers cut fast and loose with output circuits and there can be better and worse ways of dealing with them.

so take a passive electric guitar...high impedance output, instrument level ( typically -20dBu or so ) and unbalanced. This is a perfect situation for a DI to be used. A DI presents a high input impedance, some gain ( 20 to 30dB ) and balances the output. In essence it is an interface that deals with these three characteristics of the electric guitar and converts them into the characteristics that are best for connection to...consoles, converters, outboard...
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Postby heathen » Tue Jul 14, 2009 11:58 am

Depends whether you're pre's have a dedicated instrument input. Some DI's have both mic and line level outs.
If you have pre's which have no line in then you're gonna need a di to match say a bass to the mic pre's input if you want to get some vibe from say a particular pre's transformer inputs. Some di's also run on phantom power.
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Postby heathen » Tue Jul 14, 2009 11:59 am

Oops sorry Rob. :)
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Postby rob » Tue Jul 14, 2009 12:02 pm

sorry? why?
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Postby heathen » Tue Jul 14, 2009 12:05 pm

rob wrote:sorry? why?


Typing faster than I can think, no reason. :)
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Postby heathen » Tue Jul 14, 2009 12:07 pm

:) :) :) :) :) :) :)
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Postby rick » Tue Jul 14, 2009 12:17 pm

Rob , repeat after me ,
"i'm on a much needed holiday , this is the last page of the internet i will look at for a full week, my wife is having a lovely time , i might try to do the same, holiday = goodness = no work thoughts ".......:)
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Postby Luka » Wed Jul 15, 2009 12:02 am

modular == modular synth

and audio levels are around 10v peak to peak
a lot higher than line levels

so far the only real issue seems to be buffering
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