What is causing my hiss?

[foose4string]

I know, I know.....I should have gotten something QSC, but this is what I have fellas. Aside from the mixer, this is about as basic(and budget oriented) as it gets, but this is what I have:

 

Yamaha MG206c

2-JRX115 for mains

Crown XLS602

 

This gear was all purchased new a couple years ago and has never been used in a live setting. I been using it my basement at low volumes but would like to use it for a gig tomorrow(generally, we rely on another member's PA), but I am discovering something that is giving me second thought about doing so. I wanted to get a little more familiar with the rig this morning and when I try to really drive the cabs with gain or power I get a very noticeable amount of hiss. I have disconnected the monitors to eliminate that from the equation. Is there simply not enough headroom in the amp, or is it a noisy amp in general? Is the amp not getting enough signal from the mixer? It's not coming from the effects processor either, because it does the same thing if the processor is off or bypassed.

 

Obviously, I am very new to running sound reinforcement. What should I be expecting from this? It seems like the cabs should be putting out so much more than they are before I get into the hiss territory. I currently have a main hooked up to each side of the amp, and experience the same thing when I run the mains on one side of the amp and monitors on the other.

What are the optimum levels. What should everything be dialed to on this type of setup to get maximum signal to noise??? Please help a newb.

 

 

[stunningbabe]

turn down ALL mixer channels' volume to zero. You should not hear anymore hiss. If you do...that means the power amp is the culprit.

 

You should also mute every channel that is not used. Unused channels will hiss too if you didnt mute it.

[Gregidon]

I know, I know.....I should have gotten something QSC, but this is what I have fellas. Aside from the mixer, this is about as basic(and budget oriented) as it gets, but this is what I have: Yamaha MG206c 2-JRX115 for mains Crown XLS602 This gear was all purchased new a couple years ago and has never been used in a live setting. I been using it my basement at low volumes but would like to use it for a gig tomorrow(generally, we rely on another member's PA), but I am discovering something that is giving me second thought about doing so. I wanted to get a little more familiar with the rig this morning and when I try to really drive the cabs with gain or power I get a very noticeable amount of hiss. I have disconnected the monitors to eliminate that from the equation. Is there simply not enough headroom in the amp, or is it a noisy amp in general? Is the amp not getting enough signal from the mixer? It's not coming from the effects processor either, because it does the same thing if the processor is off or bypassed. Obviously, I am very new to running sound reinforcement. What should I be expecting from this? It seems like the cabs should be putting out so much more than they are before I get into the hiss territory. I currently have a main hooked up to each side of the amp, and experience the same thing when I run the mains on one side of the amp and monitors on the other. What are the optimum levels. What should everything be dialed to on this type of setup to get maximum signal to noise??? Please help a newb.

 

Hiss points to gain structure issues. You should not have any problem with the amp (i've used one quite a bit and haven't noticed any hiss issues). You may be driving the channel faders to hard and not running the channel trims high enough (the input amps on a board have the lowest noise, so they are the place to maximize signal to noise ratio on a mixer). Bring those up to where the channel strip is reading 0 at a normal input level. Then bring the channel strip up. About the best signal to noise ratio you can do is drive the board ~0 output and then adjust the amp attenuators to deliver the maximum expected output you'll need. There are trade-offs in doing this (loss of maximum output), but it should cure your noise issues.

[jwlussow]

It's gain structure. Doesn't matter what gear you are using you have a problem with your setup.

[agedhorse]

Where do you have any of the eq set?

 

Hiss is generally part of the amplification process, and nothing you have is going to be excessive in that area. What you have should perform adequately and be reasonably quiet.

 

Do you have excessive hiss with the master level control of your mixer turned down? If not, then you have eliminated two of three possible noise sources.

 

Now, start with your eq flat on your mixer, compression all the way at a minimum or off, take a vocal mic on input #1 and set your master volume on your mixer to 1/2. Then, starting with the input gain or trim control all the way counterclockwise (down) bring the channel fader up to the 0dB (or shaded) area about 3/4 of the way up. You should be able to hear the mic softly when you talk into it. Now slowly bring up the input gain control until you have good volume. How is the hiss level?

 

I suspect that your entire problem has to do with improper gain structure, excessive use of compression and excessive high frequency boost on your eq.

 

Try this and see how it sounds.

[agedhorse]

 

You should also mute every channel that is not used. Unused channels will hiss too if you didnt mute it.

 

 

Muting and turning the channel down at the fader will producte exactly the same noise level on amost all consoles.

[Craig Vecchione]

Obviously you're surprised by this hiss as you didn't get it at practice levels, but many systems will have some hiss. And there's a difference between noticeable and objectionable; If this is a rock band or other loud genre, as long as the hiss isn't noticeable during songs it shouldn't cause much if any distraction between songs. If you're a chamber quartet, that's a whole 'nother can of corn.

 

 

To set up, lower ALL faders and then PFL one channel at a time, and adjust the gain so the meter reads at or slightly above 0dB. Proceed with all inputs in this way.

 

Next, set the main level. Raise the master fader a bit, and raise the channel faders to set their relative mix levels. Adjust the main fader(s) so that again, the peaks will just go past the 0dB point.

 

Now set the amp's attenuators so that you can get maximum performance volume without any clipping on the amp's indicators. This amp has no limiting, which is a serious shortcoming, so err on the side of caution here.

 

You'll be playing a balancing act of making sure the channels don't clip, the master section doesn't clip, and the amp doesn't clip. If you need more output, raise one area if possible. Sometimes you have to drop one area to avoid clipping but can make up the gain elsewhere. The more you run this rig the more you'll get to recognize where these places are, if any. Keep in mind, the more inputs you have, and the louder you set them in the mix, the more likely you'll clip the main/master section. So adding a couple of instruments to an existing mix might require you to lower the channel faders on the entire mix, if only slightly.

[Coaster]

if this is going to be in a bar i wouldn't worry about any level of hiss; it won't be heard. air handling, bar machines, neon signs, hundreds of people talking loud, forget it.

[foose4string]

We are a rock band Craigv...a DMB tribute to be exact, but we are keeping thing relatively low key tomorrow. Drummer will have small trap kit with brushes, kick mic'ed. Mainly acoustic guitar, Very minimal distorted guitar, bass, sax, and my violin. I have excellent pitch but my hearing sux and a little white noise doesn't really bother me, but I might get a comment or two from the other guys.

 

Unused channels are muted. Faders down, except channel in use. Compression is off for the mic channel (although I tested a channel with my bass guitar using a little bit of compression). EQ is flat. I have boosted the gain slightly for the mic channel but nothing more than than 2 clicks or so. PFL shows a good signal and seems pretty happy dancing around in the green- but nowhere close to 0dB on the signal meter(maybe half or 2/3 below). Main fader sounds fine at or just above 0dB mark, but it's when I push the main fader higher that I get the hiss. Nothing I do seems to be anywhere near clipping, but admittedly, I have yet to drive anything anywhere close to bar/club levels.

 

Sorry, if I'm missing something here...there is alot to consider here and I'm slowing getting my head around all of this...

[Gregidon]

 

We are a rock band Craigv...a DMB tribute to be exact, but we are keeping thing relatively low key tomorrow. Drummer will have small trap kit with brushes, kick mic'ed. Mainly acoustic guitar, Very minimal distorted guitar, bass, sax, and my violin. I have excellent pitch but my hearing sux and a little white noise doesn't really bother me, but I might get a comment or two from the other guys. Unused channels are muted. Faders down, except channel in use. Compression is off for the mic channel (although I tested a channel with my bass guitar using a little bit of compression). EQ is flat. I have boosted the gain slightly for the mic channel but nothing more than than 2 clicks or so. PFL shows a good signal and seems pretty happy dancing around in the green- but nowhere close to 0dB on the signal meter(maybe half or 2/3 below). Main fader sounds fine at or just above 0dB mark, but it's when I push the main fader higher that I get the hiss. Nothing I do seems to be anywhere near clipping, but admittedly, I have yet to drive anything anywhere close to bar/club levels. Sorry, if I'm missing something here...there is alot to consider here and I'm slowing getting my head around all of this...

 

 

Crank up those channel gains. You are giving away SNR by keeping the input trims down.

[dboomer]

 

Main fader sounds fine at or just above 0dB mark, but it's when I push the main fader higher that I get the hiss..

 

 

Where are the meters when the fader is at "0". Again, my new crusade is the the markings don't really mean much. Unity is not the holy grail! What matters is the actual level.

 

So if your meters are hanging around -10 when the fader is at zero then you probably don't have your trims up enough.

 

I'll bet however that you mostly need to turn down your power amp by 10 dB or a bit more and turn up your mixer.

[Craig Vecchione]

I have boosted the gain slightly for the mic channel but nothing more than than 2 clicks or so. PFL shows a good signal and seems pretty happy dancing around in the green- but nowhere close to 0dB on the signal meter(maybe half or 2/3 below).

 

Nowhere near 0dB when PFL'd? Then it needs to come up. Note that you will then lower the channel fader to achieve the same signal level out to the main bus, but the resulting signal will have more gain above the noise floor....(the hiss assuming some hiss is generated in the channels).

 

I'll reiterate that some hiss is inevitable in some systems. Some are dead quiet, some are noisy. It's rarely a problem or even noticeable in the average venue space.....and at the end of the night, most people will have enough hearing fatigue that the hiss disapears along with the rest of their HF hearing....

 

Keep your levels reasonable. It's easy to get carried away when you get started in live performance. If your band is not the primary focus of the venue, be aware that people might need a space to talk comfortably, so keep volume in check if this is the case.

[foose4string]

You all were correct. I was being a little too conservative with the gain trims on each mixer channel. I turned them up a click or two and that seemed to helped a little. I hate feedback and was trying to avoid it by being stingy with the gains. Now the PFL is getting closer to 0dB with the occasional yellow. I think I found the sweet spot now and know what to look for on each channel. Thanks for all the help.

[Craig Vecchione]

Excellent!

[Gregidon]

 

You all were correct. I was being a little too conservative with the gain trims on each mixer channel. I turned them up a click or two and that seemed to helped a little. I hate feedback and was trying to avoid it by being stingy with the gains. Now the PFL is getting closer to 0dB with the occasional yellow. I think I found the sweet spot now and know what to look for on each channel. Thanks for all the help.

 

 

Glad you found your problem! Just to be clear, gain is gain is gain no matter where you introduce it in the system. You are no more likely to feedback by turning up the channel gain than by pushing up the channel slider or the master slider for that matter. Don't be pulled in by the old wive's tale that channel trim is in any way different or special vs. the channel gain. The only special thing about it is that it is a much quieter place to introduce gain than the rest of the mixer. Hope this helps, good luck and have fun!!

[Audiopyle Sound]

If you are not using them, turn your aux returns all the way off.

[agedhorse]

See, another cheap and effective solution!

[Craig Vecchione]

See, another cheap and effective solution!

 

Wait, is that good or bad?

 

[agedhorse]

Wait, is that good or bad?

 

For people that call us gear snobs and that all we do is recommend the expensive stuff I think that's pretty good.

[foose4string]

Wait, is that good or bad?

 

I see nothing wrong with cheap and effective. Expensive and kick-ass is always fun and generally much easier on the ears. However, in this case, it was just a matter of ignorance on my part.

 

Yesterday afternoon I checked out the room we are playing tonight. They have a large in house PA set up. The club is on the water with boat docks, so naturally, they are busier during the summer months. In order to cut cost during the winter they try and book things that are more acoustic oriented and do not pay to have the sound man available. They prefer bands bring a small PA and not use the house PA(apparently, they don't want risk frying the house PA and too much tweaking going on) Understandable, and not a big deal, we do it all the time with the other gear. However, I got permission from the owner to run a submix from my Yamaha board and run a line out to a single channel on their house board, using their full range speaker stacks and mightier amps. We'll provide our own monitors and power for them. At least I won't have to tote the JRX's and we'll probably have some better sounding speaks.

[jwlussow]

Get there early. You have created a more complicated setup so you may need extra time to tweak things. You make it sound a little easier then it might actually be.

[foose4string]

 

Get there early. You have created a more complicated setup so you may need extra time to tweak things. You make it sound a little easier then it might actually be.

 

 

The guy who normally runs sound there is supposed to call me and give the do's and don'ts. If I don't hear from him I will take my own cabs. It's really not that big a deal but I was looking forward to having those subs. It does sound easy enough, but I guess you are referring to getting things EQ'd. I'd have to do a little tweaking on my board regardless. If I set the input channel on their mixer flat(and the room is already EQ'd post mix) I don't see how that changes the difficulty. Care to elaborate?

[Craig Vecchione]

 

I see nothing wrong with cheap and effective. Expensive and kick-ass is always fun and generally much easier on the ears. However, in this case, it was just a matter of ignorance on my part.

 

 

FWIW, my comment was a joke. We get some folks here from time to time who get pissed if we suggest a low or no cost solution that might require some skill, learning, or lord forbid....talent, in favor of some hi-tech big-dollar magic box. An example is the bad singer who thinks a $700 pitch-corrector would be a better solution than a few voice lessons.

[Craig Vecchione]

 

The guy who normally runs sound there is supposed to call me and give the do's and don'ts. If I don't hear from him I will take my own cabs. It's really not that big a deal but I was looking forward to having those subs. It does sound easy enough, but I guess you are referring to getting things EQ'd. I'd have to do a little tweaking on my board regardless. If I set the input channel on their mixer flat(and the room is already EQ'd post mix) I don't see how that changes the difficulty. Care to elaborate?

 

 

Be sure you've got connectivity.....it sucks to show up and not be able to plug in because you have 1/4" everywhere and the rig uses XLR. Or your cables are 2 feet too short to reach somewhere important.

[jwlussow]

 

The guy who normally runs sound there is supposed to call me and give the do's and don'ts. It does sound easy enough, but I guess you are referring to getting things EQ'd. I'd have to do a little tweaking on my board regardless. If I set the input channel on their mixer flat(and the room is already EQ'd post mix) I don't see how that changes the difficulty. Care to elaborate?

 

 

I personally would use their EQ and set yours flat. Remember that they will most likely have outboard EQ, compression, limiting, gates, FX, crossover, etc... There could be a bunch of outboard gear that can destroy the system if improperly used. There are just a bunch of potential problems that can occur especially if you consider the experience level of the operators. There are people that can go in there and make everything work fine while others can make it sound really bad and potentially damage equipment that they are not familiar with. It might be worth $50 to have the guy come out to check your setup. Where are you located? Maybe someone here can help.