Members RoboPimp Posted November 13, 2004 Members Share Posted November 13, 2004 Are these things normally a friggin' hissfest? A snake den hissing away? A leaky tire slowly releasing it's life? I just picked one of these up on advice from several different people, and first impression is: I hate the hiss. It seems to sound ok but dang it's HISSY! Did I mention I noticed a slight hiss from the unit? I doubt it would interfere with live sound but I dunno, I just was happy because so far my minimalistic system was relatively quiet. Is this going to be the case as I add "needed" pieced of rack equipment? Hiss stacked on top of hiss generating amplified hiss? (Yes the hiss is annoying me and I'm being a little whiner) I stayed away from the behringer 2 31 band EQ with freq. locator... Now I'm wondering if I might have been better off ? Link to comment Share on other sites More sharing options...
Members B. Adams Posted November 13, 2004 Members Share Posted November 13, 2004 It shouldn't be hissy. Are all your connections balanced and the gain set correctly? Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 Originally posted by B. Adams It shouldn't be hissy. Are all your connections balanced and the gain set correctly? If I turn all the gains down on everything and have the EQ bypassed and it's still quite hissy? I have a 1' TS 1/4" from the board to the EQ (unbalanced) and a TRS 1/4" (balanced?) to the power amp. Should I try a TRS or XLR and see if that helps? I thought the balanced cables helped with hum (buzz?) not hiss? heheheh can you appreciate my super-technical lingo? thanks for the input Link to comment Share on other sites More sharing options...
Members dboomer Posted November 13, 2004 Members Share Posted November 13, 2004 In other words ... are the gains on your power amps wide open? ... shame, shame! Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 Originally posted by dboomer In other words ... are the gains on your power amps wide open? ... shame, shame! does the attenuator setting on the power amp change when a EQ or something is connected? How do I set the gain on the power amps? I really have no clue, it is a shame! But help me find a clue! Drop one here and there and I'll pick it up! Eventually I'll know what's going on! (yeah right) Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 13, 2004 Members Share Posted November 13, 2004 The noise floor of the 231 is quite low. I'll bet it's better than the Behringer, though both should be acceptable. I just tried a 231 that I have here and it was pretty darned quiet. You say you have the hiss problem with the eq bypassed... this should be a clue thatthere's a gain structure problem somewhere. Set everything up without the eq and see if the noise level is similar. I'll bet it's close. What kind of mixer and power amp are you using? Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 sorry if I'm being a complete idiot with this all, I really guess I have no clue... I'll go try what you all have suggested. thanks a lot for the help so far though Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 I'm using a yamaha MG 16/6 mixer and yamaha P7000S power amp (there's a local yamaha dealer who gives me good deals) I tried the board straight into the power amp and with the power amp attenuator all the way up there's minimal hiss. With the EQ inserted into the set up I have to crank the power amp attenuator to at least -6 db to get the hiss level back close to what it is without the EQ. When I use the board without the EQ I did have the power amps cranked all the way up, but that let me run the board right at 0 which is where I thought it was supposed to be? Or should the board gain be higher? It has like five more bars above 0? Am I screwing things all up or what? how do I know how to set the power amp gain? Link to comment Share on other sites More sharing options...
Members B. Adams Posted November 13, 2004 Members Share Posted November 13, 2004 I'm still curious as to where the gain on the EQ is set. It's probably best right at 0dB, or 12 o'clock. The bypass switch only bypasses the EQ section, the gain control still functions normally. With the gain at 0dB and the EQ flat at 0, it should sound exactly the same as if it weren't there. If you are applying gain with the EQ, noise will be added. Link to comment Share on other sites More sharing options...
Members RickJ Posted November 13, 2004 Members Share Posted November 13, 2004 It could be because you've had crap in your system at that insert point and now can hear what it really sounds like. Take digital photos of the front of your rack -- including EQ faders -- and post it here. I'll wager that the high end is boosted, either at the X/O or EQ. -- RJ Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 that's what's freaking me out. With the EQ in the setup, no matter where I put the gain it hisses. I started with it at 0. When I back it all the way down it still hisses. Its weird. thanks for the help everone. Link to comment Share on other sites More sharing options...
Members dboomer Posted November 13, 2004 Members Share Posted November 13, 2004 So if you unplug everything from the EQ forward does it still hiss? And you turn the gain down on the amp? still? Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 13, 2004 Members Share Posted November 13, 2004 There may be 6 dB of additional gain and noise due to the unbalanced input connection and the balanced output connection. Depends on the type of servo circuit they may be using to normalize the gain with the ring shorted to sleeve atthe input. Try all XLR balanced connections to see what's up. I would recommend XLR to eliminate the possibility of what may be happening at the 1/4" input jacks. Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 13, 2004 Author Members Share Posted November 13, 2004 sorry, I'm starting to think it's "gain structure" thing. I think I just need to attenuate the power amps more with the EQ plugged into the system. How exactly do I determine the gain structure or whatever? Where should I be putting the power amp gain control? sorry if I'm wasting everyone's time with my stupidness! Link to comment Share on other sites More sharing options...
Members dboomer Posted November 13, 2004 Members Share Posted November 13, 2004 This will get you close (but it is an over simplification)... Plug a CD or a tone generator into a channel of your mixer and set the eq flat or bypass for the channel. Pan to center. You need a steady tone that won't change throughout this whole procedure. Play a 400hz sine wave (or 700 or 1K, but lower is better). Hit the solo for the channel. Adjust the trim til you get somewhere around 0dB on the meter. Then take the solo off and turn the subs and main levels till you get just below the clipping light. Now leave everything alone on the mixer. Move to the next piece in line ... probably the EQ. Set it flat. Adjust it ins and outs till it flashes the clipping light and then back it down just a hair. Next the limiter if you've got one (at 1:1 or bypass) ... then the x-over ... then the power amp. If you are using Crown's with ODEP or Peavey amps with DDT ... these are NOT clip lights but the beginning of limiting. Go accordingly. Bring the levels up till the clip light comes on and then back it down just a little til it goes out. Don't change anything in the front stages as you move back through the chain. Now , if all your gear's clip lights were calibrated correctly by the manufacturers you are pretty close to optimal gain structure. Some manufacturers have the clip lights come on before actual clipping. Check the owner's manuals or call them. You'll have to make adjustments for specific cases. If the system is way too loud, back the power amp down to the level you need. Don't go changing anything else. As you are mixing ... don't run the mixer into clipping, but get and stay close to it (more or less). Some things that will make this different ... Some mixers will crap out if you feed the mix busses too many hot channels so you might wanna do this whole thing at a few dB down from max/clip in the first step. Also ... this might be too much power for your speakers and you might lunch 'em. That is a different subject. The method above is about gain structure only. Of course it's much better to do all of this with an 'scope hooked up to the output but if you don't have one this will get you close. The general idea is each piece of gear should clip at the same time. It's a waste if you clip one piece in the chain and every other piece still has headroom left. That's just a waste of headroom. Remember, headroom not used is headroom wasted, which is not such a bad thing ... it's just a very expensive thing. The best thing is to have a system that is many times larger than you need so you never run it anywhere near the red line. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 13, 2004 Members Share Posted November 13, 2004 Get away from the unbalanced connections. Connecting balanced gear in unbalanced configurations will almost always degrade the noise figure. It's not a problem with the eq but in how it's connected. Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 14, 2004 Author Members Share Posted November 14, 2004 Originally posted by agedhorse Get away from the unbalanced connections. Connecting balanced gear in unbalanced configurations will almost always degrade the noise figure. It's not a problem with the eq but in how it's connected. grrrrr! I've tried everything suggested here and to my untrained ear this EQ is STILL hissing like crazy. It hisses when bypassed, it hisses when the gain is turned all the way down, it hisses even more if you move sliders up. If I take the 12 Khz slider and bump it up just a little WIIISSHHHHHHHHHHHHHHHHHHHHHHHHHHHH hissssss! something must be defective right? I take the EQ out of the signal chain- which ONLY consists of the yamaha board, EQ, then power amp and its completely quiet. My wife heard it before I even mentioned it. Then I said "do you hear hissing" she replied "How could I not!?!" The built-in EQ on the board doesn't add any hiss, when you move sliders up it doesn't add huge white noise. What is going on? Maybe the gain of my mixer is too hot for the EQ? I dunno, but even though I'm loving having a 31 band EQ for my monitors I don't think I like this hiss! I will probably return it if I can't figure it out. My friend has some old but servicable ashley EQs, they're supposed to be pretty good right? any other suggestions would be greatly appreciated, and thanks to all the help I got so far. This place is certainly a wealth of good info and good people. Link to comment Share on other sites More sharing options...
Members dboomer Posted November 14, 2004 Members Share Posted November 14, 2004 Hey Robo There are two possibilities here ... broken gear or bad hookup ... OK, three if you count alien possession. It's hard to diagnoise a problem over the internet and you have not answered a couple of direct questions completely... the devil iS in the details. 1. Are you using ALL xlr balanced cables (no adaptors). You MUST try that. 2. If you unplug everything from the input of the EQ and forward. Does it still hiss with all the sliders in their zero position and the input and output controls at zero (or 12 o'clock) The fact that sliding the 12K slider up and the hiss rising with it suggests that the his is ahead of the actual filters so it's either in the input/preamp circuits of the EQ or it's coming into the EQ from in front of it. If the EQ itself is bad then you should be able to prove that by pulgging it into another system (your home stereo, a keyboard amp, etc) and it will hiss like crazy there too. Link to comment Share on other sites More sharing options...
Members Unalaska Posted November 15, 2004 Members Share Posted November 15, 2004 It's a cable thing, try all xlr (TRS if you must) and the problem should go away. I own 5 behr dual 31's and none make any noise at all, the system is dead quiet with 3.5kW behind it. p Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 15, 2004 Author Members Share Posted November 15, 2004 I have tried with all XLR cables. Would they be better than TRS 1/4"? I thought the TRS 1/4" are sheilded as well? I will try to unplug the mixer before the EQ, and I will try the EQ by itself into another amp. any other suggestions? Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 15, 2004 Author Members Share Posted November 15, 2004 Well, with nothing plugged into the EQ it still hisses. Using XLR, TRS or unbalanced cables ALL hiss the same! It hisses into another amp and speaker system. It hisses whether bypassed, turned all the way up or down. It hisses just as much or possibly MORE when freq. sliders are moved down, and LOTS more as the sliders are pushed up. Am I wrong in thinking that it should not add as mich noise as I am describing? It probably wouldn't be noticed on a live stage but I just don't like it. Although it IS functioning, I feel this EQ is either defective or just unacceptably noisy. Back to the store it goes... thanks for all the help anyway, I honestly do appreciate it. Link to comment Share on other sites More sharing options...
Members B. Adams Posted November 15, 2004 Members Share Posted November 15, 2004 Yep, it sounds like whatever the cause, you're EQ is bad. I don't think it's the design, you probably just got a bad one. Hopefully it doesn't turn you off to DBX, but in any case, I would urge you to stay away from Behringer. Any cheap Peavey, DOD or other "budget" EQ will be better than a Behringer, IMO. And that's having actually used them. Link to comment Share on other sites More sharing options...
Members agedhorse Posted November 16, 2004 Members Share Posted November 16, 2004 That's why you get a warranty when you buy a piece of gear... sometimes things happen. Now you will find out how good your dealer really is. Link to comment Share on other sites More sharing options...
Members dboomer Posted November 16, 2004 Members Share Posted November 16, 2004 So the guy walks up to the counter and says "hey can you fix my mic, it doesn't work any more". I say how do you know the mic is bad and he says "cuz when I talk into it it doesn't make any sound anymore". The truth is it could be the mic ... but it could be any piece of gear in the chain or any connecting cable. Now you know why I kept pushing you to make that test. It pretty well proves that the problem is within the DBX EQ unit. General troubleshooting is really pretty easy. You start from the back end (speakers) and go forward one cable or piece of gear after you PROVE the one behind it is working correctly. Link to comment Share on other sites More sharing options...
Members RoboPimp Posted November 16, 2004 Author Members Share Posted November 16, 2004 Originally posted by agedhorse That's why you get a warranty when you buy a piece of gear... sometimes things happen. Now you will find out how good your dealer really is. definitely!! That's one of the main reasons I bought new stuff and bought locally. I'm covered in these situations. If I had bought this EQ used I would have just had to deal with it. Same with my power amp that just went down. Because I bought it local, I got another amp to use for free and my repair was done a lot faster than if I had shipped it off. The guys at the store where I bought the EQ are also very cool and taking care of me just fine. And yup Dboomer, I see exactly why you recommended those checks, as soon as I plugged that EQ into one of my other amps and that same hiss came pouring out the speaker I knew it was the EQ. Pretty straightforward like you said. Thanks again everyone, you're all most excellent! Link to comment Share on other sites More sharing options...
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