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DI Boxes and Playing Through the PA

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The following is some simple guides to the various methods of using a DI box and playing directly through a PA.

An [b][i]unbalanced jack lead[/b][/i] is a standard jack plug to jack plug instrument cable.

A [b][i]balanced XLR lead[/b][/i] is a standard XLR male to XLR female mic lead. "Balancing" allows for improved noise rejection in the cable which gives better signal strength and allows longer cable runs.

The [b][i]PA mixer[/i][/b] is the mixer used for the Front Of House (FOH) sound.


[b]1. Standard use of a DI splitter box. [/b]

[attachment=123:DI_1.jpg]


[b]2a. Using the DI out connector at the rear of the amp. [/b]

[attachment=124:DI_2.jpg]

If your amp doesn't have one but does have a Send/Return loop that you are not using then you can try connecting a jack lead to the Send connector then put that into a DI box to convert it to a balanced XLR signal. The signal from the DI box can then go to the PA.


[b]2b. Using the Send connector as a DI [/b]

[attachment=125:DI_2b.jpg]


[b]3. Using an amp/cab simulator. [/b]

Connect straight to the PA.

[attachment=126:DI_3.jpg]

Usually there will be another output that you can also connect to your amp or a stage monitor so that you can hear yourself. For best results from your amp you want to bypass the preamp, if possible. There are different ways to do this on different amps - if there's a "power amp in" connector then use that. Alternatively connect to the Return of a Send/Return loop. If you have to connect to the normal bass-in jack then turn the gain down low initially and set the tone controls flat so that they don't affect the sound too much (the amp simulator has already shaped the sound).

As always, when connecting any two pieces of equipment for the first time, keep all of the levels (volumes and gains) down low to start with and bring them up slowly to get the correct level. This avoids damage to equiopment and ears.


[b][i]Phantom Power[/i][/b] can potentially cause problems when using method 3 above. Phantom power is a voltage (usually 48V) sent down the XLR connectors of a mixer to power condenser mics attached to the XLR channels. It does not affect dynamic mics (e.g. bog-standard Shure types etc.). It should not damage pre-amps also attached to the XLR connectors of the PA but , in some instances, it can.

To avoid any possible damge to your amp/pre-amp when conencting it to the PA, you can insert a DI bix between the pre-amp and the mixer. This will stop the phantom voltage from ever reaching the amp/pre-amp thus avoiding the problem. Having a DI-box in your kit bag will also give you a backup should the pamp/pre-amp ever fail as you can use this to connect you bass to the PA directly.

[b]Types Of DI Boxes[/b]

Types of DI boxes vary enormously. The simplest ones will have only inputs and outputs. Others are available with attenuation "pads" (to reduce the signal level) and various linking options. The most versatile ones have tone shaping circuitry (and act as mini preamps in their own right).

[attachment=127:DI20_small.jpg] Dual channel with attenuation

[attachment=128:DI_Hartke.jpg] DI box with tone shaping



[b]Links for more information[/b]

[url="http://www.soundonsound.com/sos/jun02/articles/diboxes.asp"]soundonsound.com[/url]

[url="http://en.wikipedia.org/wiki/DI_unit"]wikpedia[/url]

[url="http://www.astralsound.com/di-boxes.htm"]astralsound.com[/url]

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question:
When Di ing from the Back of a amp ( SVT cl)
Does it send the fxs from foot pedals through the Pa ( bass - effects - amp -pa)?
Tim

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[quote name='Timface' post='2329' date='May 19 2007, 06:02 PM']question:
When Di ing from the Back of a amp ( SVT cl)
Does it send the fxs from foot pedals through the Pa ( bass - effects - amp -pa)?
Tim[/quote]

Yes. All the setups shown in the diagrams above will send the FX to the PA too.

If you didn't want the fx (unlikely) then you'd have to go bass > DI splitter > FX > amp

If your FX are in the fx loop of the amp then it would depend on if the "DI out" comes before the FX send or after the FX return. You'd have to either read the manual or just experiment to find that out.

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If you are using effects - especially distortion / OD - then it is often best to run a DI send that is clean (i.e. no fx) and put a mic on your cab. Unless you know for sure what your OD sounds like DI'ed and like the sound, this will always give a better overall sound.

Obviously, this is only really applicable if you're in a venue where you're micing guitar amps too, but useful to know!

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[quote name='DrGonzo' post='10788' date='Jun 1 2007, 09:24 PM']If you are using effects - especially distortion / OD - then it is often best to run a DI send that is clean (i.e. no fx) and put a mic on your cab. Unless you know for sure what your OD sounds like DI'ed and like the sound, this will always give a better overall sound.

Obviously, this is only really applicable if you're in a venue where you're micing guitar amps too, but useful to know![/quote]


That makes good sense. OD sounds often need "softened" a little by the speaker cab otherwise they can sound a bit "fizzy". A DI taken after the FX wouldn't benefit from this softening effect whereas a mic in front of the cab would.

There's a lot a flexibility in blending a DI sound and mic'd sound like that, although it's probably beyond the scope of the average 2 minute sound check you're likely to get.

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Heh! Depends on the engineer!

I always prefer a 57 on a bass cab when there's OD involved. Done plenty of shows (in the right context) when I've not even used the DI, just a mic on a cab!

I take pride in being comprehensive even if I have to be quick, and I always do my best to get a great sound from a band. I think my record is two bands checked in 30 mins (including both of them setting up, packing down etc.). Damn touring bands with their w*nky three hour sound checks!

Mind you, I have been known to spend four hours checking a certain band I work with regularly. There are nine of them though!

Any of you guys are welcome to head through Carlisle for the best sound on the toilet circuit, courtesy of me and my partner in crime Mr Nic.

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[quote name='DrGonzo' post='10861' date='Jun 2 2007, 12:59 AM']Any of you guys are welcome to head through Carlisle for the best sound on the toilet circuit, courtesy of me and my partner in crime Mr Nic.[/quote]

Are you offering gigs slots then? :)

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Any quality, original bands doing their own thing can and will be considered!

PM me if you've got what it takes... :)

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where in Carlisle do you work? I have only played in Carlisle once, several years ago @ the Brickyard. It was nice.

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Yup, that's the place.

What band were you with then? Coupla years ago, chances are it was me that engineered the show.

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[url="http://wiki.basschat.co.uk/info:amps:playing_through_the_pa"]http://wiki.basschat.co.uk/info:amps:playing_through_the_pa[/url]

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[quote name='DrGonzo' post='22676' date='Jun 24 2007, 03:58 PM']Yup, that's the place.

What band were you with then? Coupla years ago, chances are it was me that engineered the show.[/quote]

Hehe, I've played there. You have the most obsecenly huge FOH I've ever seen in a venue of that size. I played there with Rose Kemp last year.

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[quote name='DrGonzo' post='10861' date='Jun 1 2007, 11:59 PM']Heh! Depends on the engineer!

I always prefer a 57 on a bass cab when there's OD involved. Done plenty of shows (in the right context) when I've not even used the DI, just a mic on a cab!

I take pride in being comprehensive even if I have to be quick, and I always do my best to get a great sound from a band. I think my record is two bands checked in 30 mins (including both of them setting up, packing down etc.). Damn touring bands with their w*nky three hour sound checks!

Mind you, I have been known to spend four hours checking a certain band I work with regularly. There are nine of them though!

Any of you guys are welcome to head through Carlisle for the best sound on the toilet circuit, courtesy of me and my partner in crime Mr Nic.[/quote]



If its a venue worth micing in then mines a dry DI (obviously) and an Audix D6. Ok, so you generally dont need all that sub it kicks out (feedy bass an all) but its clean a whistle, great mic for low end stuff.

As for sound check time I'll take as long I can get without pissing off the supports, crew or the band for that matter lol!

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Not read what everyones put so sorry if I'm just echoing this...

But you know the DI boxes you can put in between the amp and cab? Any good?

I play through an Orange AD200B and it has no DI out... soooo, i heard about these DI boxes, so i can have my amp sound goin' through the desk if i cant have a mic on me cab.

Cheers,
Dan.

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Hi all,
I have a Fender Bassman 135. It has a line out/ recording output at the back. please can someone tell me if this is a pre-amplified signal? I am wondering if using this output will give me a valve soumd through the PA ?If so do I really need a DI box ? can i not plug it straight into our PA desk?

Hired PA's in the past have plugged the DI box into the amp input.

Thanks for help.

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When a sound engineer is plugging a DI into your amp, they are plugging your bass into the DI input and using the 'link' output of the DI to feed your amp. This is taking a feed to the desk before any processing done on your amp, just the clean signal.

The line out should be post preamp as it will need to be boosted to line level. Generally if you are using this to feed a PA, a DI box is the best way to do it. It should then provide a good strong signal with a minimal amount of noise. Some amps line outs will be better than others, haven't used the line out from a Bassman 135 before but guess it's a case of experimenting.

Edit: I should say I have had good results using the line out from a 70's SVT into a DI box. Sorry if it's obvious but make sure you never run the amp without a speaker attached too as you could damage the transformers in the amp which are usually expensive to repair..

Edited by joegarcia

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Apologies if this has already been covered, or the answer is flaming obvious:

I use a Roland combo and it's excellent. Thinking of a plan B in case the combo when phut, I bought an XLR cable to run from "balanced out" socket on the back of the combo straight to the powered desk. I've tried it and it works tolerably well. But, that's hardly a plan B, is it? What happens if the amp part of the combo gives up suddenly - what happens then?

Is there a simple way I can connect the bass (through a DI box??) straight to the powered mixer desk without having to use the combo at all?

Please excuse my ignorance - I'm not really an "engineer" type bass player.

Steve

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Yeah you can but I dont know how it would sound.

I always carry a Sansamp with me as a back up in case my amp throws a wobbler. Recently I was gonna use the sansamp and a powered monitor and go through the pa and stop using my bass amp but decided against it in the end.

Jez

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Can someone explain exactly what ground lift is on a head and whether or not it's worth using (or the criteria on which it should be decided if it varies).

I assume it removes the head from the PA's ground which can cause/eliminate (don't know which way around it would be) hiss but it'd be useful to know because I've never had the option on an amp when I was at college in the studio. I'm just guessing though so I may be very wide of the mark.

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Ground lift separates the PA's earth/ground from that of the amp/head - this often a switchable feature on DI boxes, and sometimes on DI sends on amps. It removes the possbility of problems with earth loops, where amps and PAs are plugged into separate mains sources, which tend to give rise to hum rather than hiss.

It's worth swithing the earth lift in and out, to see if it brings an improvement in background noise levels.

One linked comment though is that if you're using a DI box and [b]no amp[/b] (e.g. for an electro-acoustic guitar/bass or keyboard), the instrument does need to be earthed/grounded to the PA for the output signal to work properly.

[quote name='ThomBassmonkey' post='744392' date='Feb 13 2010, 11:46 PM']Can someone explain exactly what ground lift is on a head and whether or not it's worth using (or the criteria on which it should be decided if it varies).

I assume it removes the head from the PA's ground which can cause/eliminate (don't know which way around it would be) hiss but it'd be useful to know because I've never had the option on an amp when I was at college in the studio. I'm just guessing though so I may be very wide of the mark.[/quote]

Edited by 27 frets

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[quote name='jezzaboy' post='711562' date='Jan 13 2010, 05:49 PM']Yeah you can but I dont know how it would sound.

I always carry a Sansamp with me as a back up in case my amp throws a wobbler. Recently I was gonna use the sansamp and a powered monitor and go through the pa and stop using my bass amp but decided against it in the end.

Jez[/quote]

Sorry to revive this thread after so long but I'm wondering how many people actually play through the PA wirhout using an amp for backline?

I've never seen it done but had a go in our rehearsal room the other day using a floor pod for amp modeling and went straight to the mixer. Sounded good to my ears, would save hauling an amp to gigs provided there was good stage monitoring.

Any thoughts?

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