Members wheresgrant3 Posted July 25, 2005 Members Share Posted July 25, 2005 Well for a year I've gotten away from not using a DI box. Even though I've had a slight hum at times coming from my mixer to our main PA and monitors, it has never been more than barely noticeable. Last Saturday that hum moved into the category of loud and incessant!!! We played a waterfront gig at a fairly popular club. As soon as I set up my keys and started loading my samples I noticed the louder than usual hum emitting from my Yorkville amps. Hoping it was just some ground interference going to my monitors, I figured I could live with it for the night... as long as that noisy output wasn't coming through our FOH speakers. Unfortunately as soon as my channels were raised on the main mixing board "BRRRRRRRRRRMMMMMMM" emitted loudly through our PA speakers. In fact, the guy who runs our sound said it was even registering on the channel LED's. For the next 20 minutes all through sound check we trouble shooted... I unplugged every cable, unplugged the monitor amps, tried different cables. It was obvious the noise interference was being produced sole by the mixer and was sending that audible signal into any ouput I choose. At this point I was sure it was a power/ground issue. Since we were so far away from the nearest power outlet I had run a 25ft extention cord and two power strips to be able to reach my side of the stage area. To be safe we plugged the extention cord into my guitarists Furman conditioner. Still... tons of hum. Frustrated we just played through the night, and our sound guy faded my keys in and out in between songs. (Me, furiously testing my connections before the gig) Of course testing the mixer last night at home I experienced no noize whatsoever. After talking things over in the "Live Sound" forum, I realize my mistake was using unbalanced TS cables to carry the balanced signal to the board. So I'm looking to order a DI Box and a pair of balanced line TRS cables (30ft long) to send my keys to the main mixer. My setup is simple. We have a full range PA that we use for gigs. In order to get my all of keys into the mix I've set up a mini mixer to mix and send the signal to our main board. ....a Yamaha MG10/2 mixer I have three synths- Triton Le, Roland XP30, and Alesis Micron in stereo (sometimes a fourth depending on space.) I also run one mic channel into an XLR Input. I run 30 ft 1/4" cables stereo out to the PA. To monitor myself I have two Yorkville Keyboard wedge amps. I run a single output to each amp and monitor myself in stereo. My question is this... how many of you use both a mixer and a DI in a multi synth setup? Does it entirely eliminate the hum and noise you may receive going through a mixer with balanced line outputs? Can I just replace the unbalanced cables with balanced and eliminate the problem? Link to comment Share on other sites More sharing options...
Members Darkstorm Posted July 26, 2005 Members Share Posted July 26, 2005 Only had hum when I had a Alesis QS6.1 synth. Alesis said that was normal due to the "absolute ground" used for the power suply. Did not have that prob with the QS6.2. Anyway for the 6.1 used a stereo Ebtech hum eliminator. Passive unit, just plug synth outs into it then run line to mixer. Better then direct boxes imo for hum eliminating. You can also try useing it after the mixer if your haveing hum problems with more then one synth. Aka mixer outs to hum eliminator, then line outs from it to amps. Got the ebtech unit from american musical Dunno what other online stores carry them. Link to comment Share on other sites More sharing options...
Members wheresgrant3 Posted July 26, 2005 Author Members Share Posted July 26, 2005 I considered that, however, wouldn't the eliminator color my sound? It eliminates certain frequencies, right? How would that affect the output of my synths and how they sound? Link to comment Share on other sites More sharing options...
Members Mr. Botch Posted July 26, 2005 Members Share Posted July 26, 2005 I would think any mixer would have XLR outs, but from the photo it looks like your Yamaha just has TRS outs? Even so, you should be able to just use XLR (ie mic) cables to the PA, using TRS-to-XLR adapters at your mixer's end. A DI should not be required. That's how I run my setup. Link to comment Share on other sites More sharing options...
Members Red Winger Posted July 26, 2005 Members Share Posted July 26, 2005 Heya Botch! Yep, that's how I run it. Small Mackie DX mixer, XLR out to main PA, no DI. No problems so far. --Mark Link to comment Share on other sites More sharing options...
Members Darkstorm Posted July 27, 2005 Members Share Posted July 27, 2005 Nope, hum eliminator doesnt color the sound nor does it filter out any frequencies. Just eliminates ac hum and nothing but ac hum. Link to comment Share on other sites More sharing options...
Members urbanscallywag Posted July 27, 2005 Members Share Posted July 27, 2005 Originally posted by Darkstorm Nope, hum eliminator doesnt color the sound nor does it filter out any frequencies. Just eliminates ac hum and nothing but ac hum. Eliminates AC hum sounds a lot to me like filtering 60Hz. Link to comment Share on other sites More sharing options...
Members Boom Posted July 27, 2005 Members Share Posted July 27, 2005 Wouldn't a DI with ground lift eliminate the ground loop, thus eliminating the noise? Link to comment Share on other sites More sharing options...
Members pipedwho Posted July 27, 2005 Members Share Posted July 27, 2005 Originally posted by urbanscallywag Eliminates AC hum sounds a lot to me like filtering 60Hz. Passive hum eliminators are just isolation transformers with the ground lifted. So should have no frequency colouring (unless you get a cheap one made with really dodgy parts). Link to comment Share on other sites More sharing options...
Members GigMan Posted July 27, 2005 Members Share Posted July 27, 2005 Grant - I'm looking at the Yam. MG10/2 mixer's manual online right now at Yamaha's web site (isn't the Internet a wonderful thing?) and it says in there that the ST OUT (L,R) jacks [which I assume means Stereo Out - Left + Right] are "impedance balanced." I'm guessing that's the spot from which you send your left + right outputs to your band's main FOH mixer? That means that you can use a cable that has a TRS (tip/ring/sleeve) male 1/4 in. plug in there. I have cables that have the male 1/4 TRS on one end and male XLR on the other - maybe you could use those. The beauty of that config. is that if you can't find a real long one like that, don't sweat it: the male XLR end can attach to the female end of a mic. cable - the other end of which is a male XLR, thus perpetuating your balanced line, from your mixer all the way to your band's FOH mixer. Link to comment Share on other sites More sharing options...
Members wheresgrant3 Posted July 27, 2005 Author Members Share Posted July 27, 2005 Originally posted by GigMan Grant - I'm looking at the Yam. MG10/2 mixer's manual online right now at Yamaha's web site (isn't the Internet a wonderful thing?) and it says in there that the ST OUT (L,R) jacks [which I assume means Stereo Out - Left + Right] are "impedance balanced." I'm guessing that's the spot from which you send your left + right outputs to your band's main FOH mixer? That means that you can use a cable that has a TRS (tip/ring/sleeve) male 1/4 in. plug in there. I have cables that have the male 1/4 TRS on one end and male XLR on the other - maybe you could use those. The beauty of that config. is that if you can't find a real long one like that, don't sweat it: the male XLR end can attach to the female end of a mic. cable - the other end of which is a male XLR, thus perpetuating your balanced line, from your mixer all the way to your band's FOH mixer. Yeah!!! I'm a dufus! I've been using regular TS instrument cable to run between our main PA and my submixer. I surprised this hadn't happened sooner. I'm just lucky I guess! I'm not taking any chances. I figure I can always find a use for a DI box anyway, so I bought a stereo DI with ground lift just in case. My local shop had a Samson Active Stereo DI box for $30. I won't use it every show but I'll keep it in my bag just in case the situation arises again. Link to comment Share on other sites More sharing options...
Members GigMan Posted July 27, 2005 Members Share Posted July 27, 2005 Originally posted by wheresgrant3 Yeah!!! I'm a dufus! I've been using regular TS instrument cable to run between our main PA and my submixer. I surprised this hadn't happened sooner. I'm just lucky I guess! Not at all (that you're a doofus) - at least not because of this particular incident, anyway... You mentioned it was an extra long run at this particular setup - betw. your mixer and the FOH mixer, right? THAT'S probably why you got the hum on this gig and not others: the other venues don't have such a far distance, perhaps... Link to comment Share on other sites More sharing options...
Members urbanscallywag Posted July 27, 2005 Members Share Posted July 27, 2005 Originally posted by pipedwho Passive hum eliminators are just isolation transformers with the ground lifted. So should have no frequency colouring (unless you get a cheap one made with really dodgy parts). Ah, 1:1 turns ratio. I see. Link to comment Share on other sites More sharing options...
Members eric Posted January 25, 2007 Members Share Posted January 25, 2007 Ok, I am dredging up this thread to ask a quick question. For years I have been sending my keyboard signals to FOH via the XLR out from the back of my pair of Motion Sound KT80 amps. I run 2 or 3 keyboards in stereo, using the KT80s as stereo stage monitors only. FOH handles my main signal summed from one or both KT80s via the built-in XLR on the back of the amp. My amp does not have a ground lift switch by the output like some do. I've noticed that about 50% of the time, there is some kind of odd hum in my line at FOH. We have tried a lot of things like dedicated, conditioned power, ground lift plugs for various items, etc. to no avail. It does not happen every time, but enough to be frustrating. I have decided to do something about it and my options are either a bunch of DIs or a mixer with XLR outs. I was also considering something like the new Traynor K4, which is the single stereo combo amp with a ground lift included. But that is pricey. My basic question is this: If I got a small mixer like the Mackie 1202 with balanced XLR outs, would this alleviate my hum or do I need to get something with a ground lift on it (like most DIs?). I am torn between the mixer and considering some kind of pro DI solution like the Radial JD6. Any comments appreciated. Thanks,Eric Link to comment Share on other sites More sharing options...
Members wheresgrant3 Posted January 25, 2007 Author Members Share Posted January 25, 2007 Eric, I spent the $30 and used it in my setup... and I haven't looked back. I probably don't need the ground lift for every room but if I have it, why chance it. I have a short (1ft) TRS cable that plugs between the mixer and DI (everything is velcroed down)... and I just connect to the to the FOH with a pair of XLR. In fact when I accidently hit the ground lift button (and disengage it) you can usually hear a buzz. Witrh the GL engaged it's so quiet you can hear a pin drop. Usually the greatest offending rooms are resturants, bars with kitchens, and hotel ballrooms. Basically any room that may be running a freezer, microwave or hair dryer on the same circuit will provide misery. Link to comment Share on other sites More sharing options...
Members submodern Posted January 25, 2007 Members Share Posted January 25, 2007 I've got that Ebtech Hum Eliminator and have never had a hum problem. As a bonus, it also works as an unbalanced->balanced converter. The one problem I've had using it is that sound guys hate interfacing to 1/4" jacks. Several times I've had to run the set in mono because they only had one cable or had to jury rig something together to make it work. If I brought my own balanced 1/4"-XLR cables, or even just some sort of adaptor, that wouldn't be a problem. Link to comment Share on other sites More sharing options...
Members eric Posted January 25, 2007 Members Share Posted January 25, 2007 Thanks guys...I would really like it if there was *one* solution rather than coupling 2 together, but Grant seems to have a pretty decent thing going on there. I don't believe the ground lift is a common feature for mixers and there really aren't too many multi-channel DI boxes that sum the channels like a mixer would. There have been a few times when I've played gigs with 3 keyboards and a BIG sound company will actually whip out 6 individual DIs for all my keyboards. Then I'm stuck trying to find enough patch cords to connect everything (need 12 between in and thru jacks). So having a small mixer like Grant's or maybe a Mackie, coupled with a DI (only for desperate ground lift situations) would be the ticket for a multi-keyboard rig. Regards,Eric Link to comment Share on other sites More sharing options...
Members submodern Posted January 25, 2007 Members Share Posted January 25, 2007 For a small mixer you might want to look at the Tapco line that Mackie has recently put out... they are cheap, simple, reliable (in my experience at least) and work great for live stuff. That's actually what I currently use, then through the Ebtech, and then to the house. Definitely it's a good idea to have a DI/Ebtech/whatever in the bag, along with a variety of extra adapters (take your own advice submodern!) and cables just in case... Link to comment Share on other sites More sharing options...
Members Khazul Posted January 25, 2007 Members Share Posted January 25, 2007 I would check that Yammie mixer out - there are real stingey sods when it comes to providing balanced outs. They do at least have the decency to label them as bal or unbal on mixers. For some strange reason they seem to think the only people buying high end mixers need balanced outs... The other thing that comes to mid as a possible cause - how long was the mains to your keys rig vs mains to your main desk? (I assume both from same power point?). A common cause of this kind of agrivation is different point in the chain being at difference ground levels due to having difference lengths of copper to ground. Link to comment Share on other sites More sharing options...
Members BluesKeys Posted January 25, 2007 Members Share Posted January 25, 2007 Eric, I am going to a mixer/ two DI's for the solution. I know Learjeff has a 2 channel DI but I haven't run across a 3 channel DI. I use two boards and a module and like you that equals 6 DI's and all my cords. Link to comment Share on other sites More sharing options...
Members wheresgrant3 Posted January 25, 2007 Author Members Share Posted January 25, 2007 Yeah the Samson DI probably isn't the best choice (I see Berhinger must get them made at the same factory in China... same body type differen't paint job) but it does the trick. Actually this kit I built was pretty useful. The Yammie mixer was $99, the DI was actually $39 and the case was $49 for MF (It's a Core One small case for effects pedals). I'm considering replacing this with a Rolls Line mixer in a rack case (I traded with GigMan ) but I'm on the fence. The thing I like about the Yammie is that I can set my keys levels based on the LED's. For instance if a horn stab needs to be trimmed back... well that's not always the easiest to hear onstage behind the FOH... however if I see the LED light up like the Space Shuttle taking off I know immediate there's a problem. I've gotten very use to this setup when we didn't have a dedicated sound guy. Now that a good protion of the room we play have great sound guys it's problem time I moved to the Rolls, set it, forget it and let them ride the fader. Link to comment Share on other sites More sharing options...
Members a_rose2025 Posted January 25, 2007 Members Share Posted January 25, 2007 Gosh.... the guy up there who thinks he's a dufus has got nothing on me. All I know is how to play my keyboards-- getting other people to hear them when I play out is way over my head. Seriously. I know the XLR outs on my Roland amp have buzz problems so I use the clubs' DIs, but that's about it. Please help me understand balanced vs. unbalanced outs, and impedence. While you're at it, could you suggest a specific combination of items that would let me mix two keyboards (or three with only one running in stereo) and not have a buzz? My only note is that despite my cheapness, I'm reluctant to go with a passive line mixer because the nord electro always comes out quiet as a mouse. Thanks for your advice (and for minimal mockery). Link to comment Share on other sites More sharing options...
Members GigMan Posted January 26, 2007 Members Share Posted January 26, 2007 Thanks guys...I would really like it if there was *one* solution rather than coupling 2 together, but Grant seems to have a pretty decent thing going on there. I don't believe the ground lift is a common feature for mixers and there really aren't too many multi-channel DI boxes that sum the channels like a mixer would. There have been a few times when I've played gigs with 3 keyboards and a BIG sound company will actually whip out 6 individual DIs for all my keyboards. Then I'm stuck trying to find enough patch cords to connect everything (need 12 between in and thru jacks). So having a small mixer like Grant's or maybe a Mackie, coupled with a DI (only for desperate ground lift situations) would be the ticket for a multi-keyboard rig.Regards,Eric Eric -Currently you run your rig into the the two KT80 amps, right - I guess a patch cord from the "Left" output on each keyboard to one KT80 (by your left ear?) and a patch from the Right out on ea. 'board to the other KT80 (by your right)... is that how you run it? And then, what - you send the XLR out from the "Left" amp to the FOH, since most sound companies don't know/care/deal w/stereo signals and run in mono...? So if you add a mixer & DI/ground lift - you'd what, run the L+R inputs to the mixer, then a mono out to the ground lift & from there to FOH? Link to comment Share on other sites More sharing options...
Members ramkeys Posted January 29, 2007 Members Share Posted January 29, 2007 Get Behringer Ultra-di Pro4 Channel Di (or 2 Stereo)Has Ground Loop $80.00 Only Send Xlr To House Use Splitter For Your Mic In Mixer...take Control $65.00 Richard Link to comment Share on other sites More sharing options...
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