Back ground noise from bass amp

[2cool]

Hi guys, sorry if this is a repost I couldnt find the thread but I am getting (for a lack of correct terminology) background noise through my mains from my bass players amp. I just run a 1/4-1/4 from his out to the snake. If he turns down his volume to less than half it is not so bad but since I cant put him on his own monitor so he has to turn up to hear himself. I am just turning down his slider in between songs. I am guessing a Direct Box would help as I think it is a grounding issue but I am not clear on the whole grounding topic.

[waynehoskins]

There may be a couple of factors at play, but it's hard to tell. If it's hum or buzz, that sounds like a balancing problem. A DI box can help, since it balances the signal before the long run; long unbalanced lines tend to pick up electromagnetic noise. Hum can also be picked up by single-coil pickups (the reason why the humbucker pickup was developed, to "buck" the hum).

Hum or hiss, if you can't eliminate it before it comes in (pickups, cables, DI, etc.), a noise gate is the quick and dirty solution. Insert it on the bass channel and set the threshold low enough to not interfere much with the playing but high enough to gate out the noise.

[bbrunskill]

Buy a cheap DI. The whirlwind IMP is good, and they are only $20.

[Frank DeWitt]

Originally Posted by bbrunskill

Buy a cheap DI. The whirlwind IMP is good, and they are only $20.

I think base needs a good transformer. I don't believe a cheep DI will do the job.

Disclaimer, I build and sell DI boxes.

Frank

[Tim Padrick]

Forget the super cheap DIs - get at least an Audiopile.net DI.

[2cool]

The church is a start up borrowed pieces etc. They are buying equipment little by little. I hope this might work Behringer DI20 Ultra DI 2-Channel Active DI Box/Splitter. I want to use it on the bass and E.guitar.

[Brad Weber]

Active DIs were developed to accept the low level output and present a proper high impedance load to passive instrument pickups, thus avoiding distortion and high frequency roll-off. With higher output, lower impedance active electronics a transformer based passive DI may provide isolation and be more RF resistant.

Keep in mind that low frequency saturation is one of the potential issues with small/cheap transformers so bass is probably a less than ideal application for cheap, passive DIs.

[yeshua]

Question: This output on the amp, is this a passive DI output? a powered output? (plug in a passive speaker to easily test it) 1/4 out on the amp makes me wonder what is the signal actually coming out...(granted I don't have lots of experience with amps)...most amps I've seen have either an internal DI which then just has a XLR out, or powered 1/4 outputs for 2ndary speakers...

Try these to see if that helps the buzz:
1. a DI between the bass and the amp (using the thru 1/4 jack to go to the amp, XLR to the mixer)
2. a DI from the amp 1/4 out, using the DI XLR out to the mixer
3. Mic the amp itself with a microphone (use this if all the direct methods don't work, or if you really want the "amp" sound vs the "guitar" sound)

As for DI's, I've got a couple of http://www.artproaudio.com/products....cat=13&type=90 and they are only $50 I think, we've got another model (can't remember exactly what it was) but my guitarist/bassist prefers that art vs the other one...But make sure you only get DI's that have a thru jack...I wouldn't want one without it....

For the behringer, well most people say don't go with them at all...not worth it...I say it depends....I needed something cheap to control the volume on my sub from FOH...I bought the Behringer MICROAMP HA400 for $20 and it works great for it. I don't have any problems with it, and I know if it dies, well it was $20 out of my pocket (my sub I added from my home stereo, so my volume control...not gonna make the church pay for that). I'm ok with Behringer as long as I'm not spending more then probably $150 on the really high end. I'm not sure what that DI20 costs, but I would probably rather get any other one (mainly because it doesn't have a thru jack).

I'm not sure what feelings people have about having a 1 channel DI box vs. a >1 channel DI box, but I would also sooner have single channel boxes vs multi channel....just so I can put 1 channel here and one channel there, then the next week put that other channel there instead....

Although my church is not a new start, we are only a small congregation of 50 with a portable system since we are in a gym, so we may very well be in a similar situation, if you have any questions, feel free to ask me anytime. I also have an older video of our setup on my site if you want to check it out....(its about a year old, we've added an imac instead of the laptop on stage and a few other things....need to take a new video....)
http://web.me.com/yeshua11/Joshs_Website/Extras.html

[daver2]

WARNING! We have a Behringer 2 channel active DI box (not exactly sure which model it is) which I refuse to use as it is a noise generator! Someone used it the other day for a guitar and I could hear this hiss coming from somewhere. Once I saw the little shiny box and swapped it for one of our passive units - everything was nice and quiet once again.

Moral of story - cheap is generally cheap for a reason!

I think our passive DI's are also made by Behringer so I can't comment on the company - but the active DI unit we have I would never recommend to anyone. I will post the models of the active and passive units when I am next at Church.

Another possibility is just the signal to noise ratio of the bass guitar electronics. If he has his gain up too much then you will be amplifying his noise as well as the signal. If he turns his gain down a bit (to reduce his noise) then you can turn the mains up a bit and everything will be OK. Again, we had a similar problem a while ago. Re-adjusting the gain structure got rid of the noise and everyone was happy. From what you say above you are a bit limited with what you can do here though.

Dave

[2cool]

Thanks Josh and Dave, that was very helpful information and I will not be buying the "B" box. So I want something with a THRU function and yes I tried the gain technique but very little help with that tactic.

[Tim Padrick]

One of the few truly good bass sounds I've been given (as a mixperson) was a stock American Jazz through an Audiopile.net active DI. I prefer an active DI for a passive instrument, but every now & then I have to switch to a passive DI owing to there being something screwy about a player's amp.