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chrisanthony1211

How do you connect to the PA?

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I should know this by now so bit of a Luddite question!
I normally just take unbalanced XLR out the back of my amp to the 1/4 inch input on the desk, our keyboard player who is our “techie” is on about introducing a DI box between my guitar and amp and taking this then to the desk, so effectively the bass amp just becomes a monitor and doesn’t colour the sound going to the desk.
I also use a tech21 fly bass rig which has a DI out from it, I suppose this would be the same as a DI box? So this going straight to the 1/4 input on the desk would be he same, would it ?

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Is there not an xlr that the DI box could use (on the desk)? This would allow the use of a standard mic cable and have the advantage of not being length-restricted (and one less specialist cable to cart around).

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[quote name='Steve Browning' timestamp='1510309820' post='3405451']
Is there not an xlr that the DI box could use (on the desk)? This would allow the use of a standard mic cable and have the advantage of not being length-restricted (and one less specialist cable to cart around).

[/quote]

Ah, so using a standard unbalanced XLR cable, but using the pad on the desk to reduce the input signal?

And what advantage does the DI box give you over using the DI from the Amp?

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So you're going XLR out of the amp, to 1/4" input on the desk? Why not go XLR to XLR?

The advantage is then the impedances of the input and output are matched so you get the most efficient transfer and the balanced XLR output should have a lower noise level.

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There can be quite a lot of unwelcome electrical interference in a stage environment especially if you have lighting dimmers around so it is wise to take whatever precautions you can to minimise this. One way is for all long cables to be balanced as this will help cancel out any interference and hum. Ideally you should keep unbalanced cables short and use balanced cables where running across the stage to, for example, an FOH mixer. This is why most amps and all DI boxes have a XLR output so you can use a balanced connection to the mixer.

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[quote name='chrisanthony1211' timestamp='1510310526' post='3405458']
Ah, so using a standard unbalanced XLR cable, but using the pad on the desk to reduce the input signal?

And what advantage does the DI box give you over using the DI from the Amp?
[/quote]

The DI output will convert the signal to (effectively) a mic signal. You won't need any pad on the input. An xlr to xlr is (usually) balanced which allows for the long cable run. Just plug into the xlr input on the desk and treat it as if it were a mic.

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The desk you're using does have XLR ins, doesn't it? If so, follow advice above re. using a balanced mic cable from your DI to it. Personally, I'd use the DI out on the Tech21, unless you're using dirty or heavily overdriven bass tones. Going straight to the PA from the instrument via a DI box tends to give a very sterile sound that the eq on the average desk can't do much to correct.

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[quote name='Dan Dare' timestamp='1510311921' post='3405475']
...

Going straight to the PA from the instrument via a DI box tends to give a very sterile sound that the eq on the average desk can't do much to correct.
[/quote]

This is the answer you’re looking for.

I suspect the Keys player doesn’t like the way you’re EQing your amp and it’s not suiting the front of house PA.

It’s a legitimate reason. You’ll need to experiment and see what the bass DI direct to the PA sounds like.

Or as Pete says. If theres a pre/post switch on the amp DI you don’t need that additional DI box.

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The Mesa Walkabout has a balanced DI, post EQ and FX loop. You'd normally use that plugged into the console directly with a balanced Xlr cable, as if it were a mic. There is no provision for pre-eq, however, so FOH will receive your EQ and FX loop sound.
The Fly Bass rig also has a DI out, equally post FX. There is no provision for having a Pre DI, so FOH will receive the FX.
If your sound fellow wants a 'dry' bass signal, it'll require the bass to be plugged into a DI box before the Fly Bass, with the Fly Bass chained from the DI box.
Hope this helps.

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[quote name='chrisanthony1211' timestamp='1510310526' post='3405458']
Ah, so using a standard unbalanced XLR cable, but using the pad on the desk to reduce the input signal?

And what advantage does the DI box give you over using the DI from the Amp?
[/quote]

A proper DI box will have galvanic isolation and a ground lift switch so you can break any hum loops and it will be pre-eq and any signal processing so it is as faithful to the true bass tone as possible. (that may or may not be the thing that is required though - sometimes the post-processing signal is needed instead - depends if fx are being used)

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Assuming the PA has subs and you have a monitor, I'd use the Tech 21 only & leave the bass amp & cab at home.

Take the XLR out on that straight to the appropriate XLR in on the desk.

The Bass Fly rig has the Sansamp built in + a compressor, so you should get a good tone out of that set up.

Edited by Wilco

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[quote name='Happy Jack' timestamp='1510321170' post='3405573']
It's complicated.
[/quote]

It's my guitarists job. He owns the PA and knows what he's doing. I turn up on time so he can plug stuff in to my amp. That's all I know.

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One thing you might come across is that operators of house PAs or PA hire firms may get bolshy about using their own DI boxes regardless even if you have a perfectly useful DI xlr out on your amp. This can be for number of reasons. They may not trust your DI out but know their own gear well , they may consider it an H and S issue or they may be numpties that don't know what your DI out is or how to use it. A shining example of the latter can be found at Leeds Hop should any of you be going to play there.

I insist on using my amps own - which has pre/post eq and a ground lift like most do.

There are a couple of basschatters who may remember this because they were at the event - the last time I gave way was at Pendle Leisure Centre during the Colne R and B fest. and I only did it because the band didn't want me 'making trouble'. As if !! Anyway - these 'professionals' managed to wrongly rig up some phantom powered box or other and sent 48 volts straight into my (then) brand new active Shuker and fried it's internal electrics. I moaned about it on here at the time and there were those more technically minded than I who said I could easily have been fried myself. This was a large reputable (!) pro PA hire firm , not some 100 spot monkeys so it does happen.

Stick to your guns - stick one end of a mic lead into your xlr DI out ( I'd always suggest you retain control over sound changes you make by going post eq )and the other into a stage box or mixer input. Remember the beauty of mic leads is you can easily connect more than one together to get longer cable runs and I always keep a couple of 10m jobs in my gig bag for that purpose. Don't buy black ones as the PA guys will nick them by mistake or otherwise.

Subject change but I use my own mic on house/hire PA jobs too. Pontefract liquorice festival and the subsequent dreadful throat infection taught me that. Like a rat had crapped in my throat then died there.

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Wasn't my amp - hired in ampeg top and 8x10 - I've little recollection of what went where , I just stupidly , and under time pressure from everyone gave the end of my guitar lead to someone who stuck it straight into some box or other that was hanging out of the Ampeg. My bass wouldn't work and everybody was on at me for 'not changing the battery' and if it'd gone on I'd have chucked my teddy so I grabbed my Precision , plugged it into the ampeg myself - told anyone not to come within ten feet or I'd deck them and did the gig like that. It was Jon Shuker who figured out and told me what had happened when I took it to him for repair.

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Tbf I'm not sure all ampeg heads have a DI on the back so the sound crew might have had no choice, still not great putting the phantom up you though. I'm not sure that's supposed to happen either tbf, the phantom should just power the di box to save batteries afaik?

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It may be about which mixer you use. Some cheaper mixers use the jack input as a line level input and the XLR as a mic level input, which is much lower. If your amps DI output is line level it would be too high output for the XLR mic input. If the mixer has no way of padding (reducing) the input then you can't use it with the XLR to XLR connection. Using the jack connection is better as explained above because it is quieter. Using the DI will allow your guy to match the inputs and use a low noise connection. It means you lose control of what the bass sounds like out of the PA.

It's also possible that he wants to do this because it's just what PA engineers do. We're control freaks and also creatures of habit. If you want to send your own eq'd sound then ask him why he can't just run your DI out straight into the XLR/mic input on the mixer. If it's a mismatch then you could use the DI box to pad down your post eq signal. Or if you trust him just let him get on with it, maybe get a long lead and go and listen to the bass through the PA, once he knows the sound you want he should be able to hit it pretty much every time.

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XRL from my amp , which I believe goods right into the board on stage. Then, I I think the board is interfaced with our sound techs lap top.

Does that sound right?

Blue

Edited by blue

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[quote name='stingrayPete1977' timestamp='1510335997' post='3405759']
Tbf I'm not sure all ampeg heads have a DI on the back so the sound crew might have had no choice, still not great putting the phantom up you though. I'm not sure that's supposed to happen either tbf, the phantom should just power the di box to save batteries afaik?
[/quote]

Phantom power is used to power condenser mics.

Some equipment will ignore it. Some will go up in smoke.

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[quote name='Phil Starr' timestamp='1510337230' post='3405779']
It may be about which mixer you use. Some cheaper mixers use the jack input as a line level input and the XLR as a mic level input, which is much lower. If your amps DI output is line level it would be too high output for the XLR mic input. If the mixer has no way of padding (reducing) the input then you can't use it with the XLR to XLR connection. Using the jack connection is better as explained above because it is quieter. Using the DI will allow your guy to match the inputs and use a low noise connection. It means you lose control of what the bass sounds like out of the PA.

[/quote]

A way round this is to buy a passive DI box and run a feed into it from the effects send on your amp (which shouldn't be at a very high level). Most mixers will have an input gain that starts from below zero gain, which should accommodate all but the hottest signals.

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[quote name='TimR' timestamp='1510337599' post='3405788']


Phantom power is used to power condenser mics.

Some equipment will ignore it. Some will go up in smoke.
[/quote]

Good point. Check the manual for your amp and if in doubt, don't risk it. A passive DI box transformer will ignore phantom power. If you get an active one, you can use the phantom of course.

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Most modern amps already have isolated DI's to cope with someone turning on the Phantom Power on the bass channel and will deal with it without blowing up. I allways tell teh song guy about my good quality amp DI wich has mic/line , pre/post and lift/ground switches as well as it's isolated from 48v power and offer to use theirs if they prefer, no one has turned mine down yet. The trick is to give them the choice, make them choose between a very good amp DI and the cheap BSS AR133 in their hands ;) I allways go post DI without their knowlege as even though i set my EQ flat everywere my amp has an internal HPF that clears all the muddy low end out and gives more definition to my notes.

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