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View Full Version : AMP DI to mixer/PA - help!



cactoose
11-29-2010, 04:15 AM
Hi all,
We want to run the DI's from our guitar amps into a Yamaha mixer/PA. All the amps have XLR DI outs and the inputs on the mixer have either an XLR input or jack input on each channel. We want to DI through the amps to keep our tone.

Two question for you:
1. Should the cable from the amps be XLR to XLR (into the XLR input) or XLR to jack (into the jack input)
2. Running this setup, could we still use our amps as backline or will the mixer take control of the volume?

Many thanks

Chris

slejhamer
11-29-2010, 10:04 AM
1. If the amp's DI out is XLR, then run to the mixer's XLR; this should give the best signal-to-noise ratio over longer runs, and also should properly match the impedance between amp and mixer. It is possible the mixer's 1/4" input is for high impedance signals (e.g., instrument-level, as opposed to microphone level); read the manual to find out for sure. I had a Yamaha mixer with high-impedance 1/4" inputs and I used an in-line impedance balancing plug for better results. Also most standard instrument cables with 1/4" plugs are not balanced, and over long runs you could lose signal or add noise; if you do use the 1/4" inputs, you'll probably want to use balanced (TRS) cables.

2. Not sure I understand your question; the mixer/PA should be controlling the FOH ("front of house") volume. Your amps on stage can be set to levels where you are basically using them as monitors, or they can be cranked up to supplement the PA. Then it's up to your sound man (or woman) to balance the levels. Also, some amp DIs have seperate level controls, independent of the amp's volume, but often the amp's volume dictates the signal going to the mixer, and the sound person will have to adjust the input gain at the board.

One thing to find out, which may be more important for electric guitars than bass or other instruments, is whether or not the guitar amps have cabinet simulation in the DI signal. The speaker cabinet can be a huge part of an electric guitar's sound, which a preamp output may not capture. If the guitars sound like fizz in the PA, that could be why.

Hope that helps.

cactoose
11-29-2010, 10:17 AM
Thanks very much slejhammer, this stuff is all pretty new to me so I'm trying to learn fast!

1. XLR to XLR is doable on the mixer, but I'm having trouble finding male to male cables. I'll continue my search.

2. You totally understood the question :) - I assumed that if the XLR's were coming out of the amp into the mixer, that we would lose control of the amp volume (our onstage volume, not FOH), but I don't think this is the case now.

I believe the guitar amps to have cab simulation. But they are mainly playing acoustic instruments anyway (guitars, mandolin and banjo), so the cab sim may not be so important, so I've read? We are fitting everything together over the next few days, so I'll know for sure.

Thanks so much for your help.

slejhamer
11-29-2010, 12:27 PM
You're welcome. I was a stage technician in a past life and I help with sound at church, so I'm happy to offer what little knowledge I've got on the subject.

You are correct, with acoustics you won't need cabinet sims. More of an issue for electric guitar amps, where you don't see XLR outs very often anyway.

What is the make and model of the guitar amp your bandmates are using? I'm surprised you'd need a male XLR plug at the amp end, as the XLR out jack on an amp is usually male. Many acoustic amps do have XLR inputs (for microphones) as well as outputs, though. They are basically mini-PAs.

You would lose control of your stage volume if you were running direct to the mixer, and using that to control passive stage monitors. That's how we've got our acoustics, keys, and vocals set up. But I'm a control freak (and I don't trust our sound guys, lol), so I use my own amps for bass or electric guitar the way you are using yours, and I set my own stage levels as I need to. If anyone complains I'm too loud, I just get the sound guy to bump everyone else up to my level. :cool:

cactoose
11-29-2010, 01:21 PM
You are totally right, I have checked and I don't need male to male.

The PA is a Yamaha Stagepas 500 with 2 x active Yamaha MSR100's as floor monitors (the PA can adjust the volume for the monitors, but that's all - so you hear the FOH mix through them).

One of the guitarists uses a Laney A1, the other a Marshal AS50D. Both are acoustic amps with XLR DI out, but doesn't look like they have cab modelling (you were right again!).

Having checked with them, all the instruments are acoustic or semi acoustic (mandolin, banjo, dreadnoughts and a Tokai ES60 semi acoustic gibson copy). So I suppose all can go into PA direct without DI boxes?

Thanks again,
Chris

TLDTR
11-29-2010, 01:22 PM
Well done, Slej -
Thanks!
Ed.

slejhamer
11-29-2010, 07:36 PM
Having checked with them, all the instruments are acoustic or semi acoustic (mandolin, banjo, dreadnoughts and a Tokai ES60 semi acoustic gibson copy). So I suppose all can go into PA direct without DI boxes?


Possibly. I checked out the Stagepas' manual, and it looks like each input can be set to mic or line level, but not variable in between. So obviously if you are mic'ing an instrument, set the input to mic level (and if it's a condenser mic, turn on phantom power if you need it.) With the DI outputs from the amps, you'll have to see which setting works best (probably mic, but some amps send out a much hotter line-level signal. There might even be a switch on the amp to adjust the DI output level.)

The output level from instrument preamps like those in acoustic guitars can really vary though, and you might find best results running them through DI boxes anyway.

All the DI box does, at the most basic level, is take your instrument's signal level and convert it to mic level, which makes it more mixer-friendly. It's also outputting a balanced low-impedance signal, which is going to maintain its strength and not pick up noise over longer cable runs. And, they can help you defeat ground loops that cause hum.

So, DI boxes are good to have around, and you can often find them used for cheap. I recently scored a DBX DB12 on ebay for $18, in like-new condition. They're normally $140 online! I also grabbed a trio of BSS Audio AR133s for church at less than half price. More popular brands like Radial and Countryman are tougher to get good deals on though.

We've had trouble with the really cheap brands like Behringer. Honestly, I keep a Behringer as a backup because it's better than nothing, but they are just not reliable for everyday use, imho. And I laugh at one of my guitarists, who brings his $1800 Martin to church and then plugs it into his $20 Samson ... just makes no sense to me.

cactoose
11-30-2010, 10:02 AM
Once again, thank you. i have send our guitarist a link to this advice, so we'll see how it sound tomorrow and we'll decide on DI boxes. I had a quick look around and found something called a Radial JDI that seems to be respected among acoustic players. One of your suggestions!

But the very best thing to come out of all this is that i have had to upgrade my bass amp to this...

http://www.bassdirect.co.uk/bass_guitar_spe******ts/Phil_Jones_Bass_Cabs_files/1244_1.jpg

I'll let you know how things go.

Thanks again,
Chris

slejhamer
11-30-2010, 10:53 AM
LOL, any reason to buy more gear is a good reason! :cool:

Pointbass
01-02-2011, 06:20 PM
If you double you might want to check out the Radial ToneBone BassBone. Great DI, plus you can use two basses EQ'd to your liking and easily switch during a set ....