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pre-amp hiss through pa

#21
You are only as good as your knowledge. I've always been amazed how many bass players don't know how their own gear works when I do live sound. On the other hand, there are some guys that can come in with multiple instruments and complex rigs and you can hook 'em into the PA and they are sounding good in moments. They really are pros.

RTM. Always. And reading other stuff that's related always helps. This goes for all the lameass sounmen out there who don't know gain structure and therefore are of no help.

Ths has been a public cervix annoucement.
 
#24
I agree with greenboy that educating yourself on signal flow, gain staging, and signal to noise ratio will benefit you for the rest of your playing life. In the meantime, here are a few quick tips:

  1. Don't use the input pad unless you have to (meaning, unless your instrument's output is so hot that it distorts the preamp).
  2. Don't be too conservative with the input gain control. You want to use as much gain as possible before distortion. Obviously you should leave yourself a little headroom but the idea is to feed the rest of the preamp a loud, clean signal (tech speak: maximizing the signal to noise ratio).
  3. If the DI signal is post-compressor, try disabling the compressor. The very act of compressing a signal will raise the noise floor.
  4. If you aren't running the preamp's master volume control at 50% or higher then you should turn your power amp down and turn your preamp up. I agree that it's more convenient to adjust the volume from the preamp but the power amp needs a loud, clean signal. Again, we're maximizing the signal to noise ratio. Your power amp probably has meters (or at the very least a clipping indicator light) on the front so you can see when you're sending an adequate signal.
 
#25
testing1two said:
I agree with greenboy that educating yourself on signal flow, gain staging, and signal to noise ratio will benefit you for the rest of your playing life. In the meantime, here are a few quick tips:

  1. Don't use the input pad unless you have to (meaning, unless your instrument's output is so hot that it distorts the preamp).
  2. Don't be too conservative with the input gain control. You want to use as much gain as possible before distortion. Obviously you should leave yourself a little headroom but the idea is to feed the rest of the preamp a loud, clean signal (tech speak: maximizing the signal to noise ratio).
  3. If the DI signal is post-compressor, try disabling the compressor. The very act of compressing a signal will raise the noise floor.
  4. If you aren't running the preamp's master volume control at 50% or higher then you should turn your power amp down and turn your preamp up. I agree that it's more convenient to adjust the volume from the preamp but the power amp needs a loud, clean signal. Again, we're maximizing the signal to noise ratio. Your power amp probably has meters (or at the very least a clipping indicator light) on the front so you can see when you're sending an adequate signal.
Click to expand...


So just so i understood that right

[*] kick the -15 button
[*]more gain, less channel volume
[*]run pre instead of post

as for the last part of that w ith the power, the master is usually past 12 oclock and i get a pretty good signal on my poweramp (crown xls drivecore 1500)

one piece of advice i got from a local sound guy who is also a bass player was just set everything where it just about clipped. and just adjust my active controls from there.
 
#26
brenner182 said:
one piece of advice i got from a local sound guy who is also a bass player was just set everything where it just about clipped. and just adjust my active controls from there.
Click to expand...

Kinda sorta. The key is finding and matching the clip thresholds amongst all the parameters and components. It can be difficult in your case as only the preamp gain and power amp have signal & clip indicators; the master preamp volume does not. As suggested, a 50% volume setting should register a strong corresponding signal on your power amp without "red lighting" the affair. The concept is easier to demonstrate within the context of mixer / amp relationship where each step of signal processing can be monitored (pre-fader listeners, bargraphs, clip LED's, etc.) and adjusted accordingly.

Riis
 
#27
brenner182 said:
That was supposed to say power amp. soryy sorry lol. i do not run the pre amp wide open i run the power amp wide open.
Click to expand...
There's your problem.

You've cranked the power amp all the way up, so you have to turn the preamp down to get a reasonable volume, thus bringing your bass signal down towards the noise floor of the preamp. This would be a good way to maximize the hiss from your preamp.

You should have the power amp turned down as far as possible, and the preamp should be turned up as high as possible without clipping. Turning OFF the pad (unless you get clipping at the input), turning up the input gain until it clips a bit, then back off just a little, turn up the master out of the preamp, until it clips, then back it off, then turn the power amp up to the bare minimum to get the volume on stage that you need.

Preamp puts out hiss, no way around it, they all do. The trick is to get the signal much higher than that residual noise.

Randy
 
#28
OK now that i got some free time to write a follow up.

Switched it to pre on the back, took my limiter off and tried everything from there.
We had a new sound guy that night so i dont know how it sounded out front to be honest. only complaint i heard from the sound guy was that i needed to turn down. lol

one thing i did notice was that with the -15 switch off it was alot more... pronounced? and switching basses back and forth between basses required adjusting each time.

And the place we played was big and open, and i can never find a sound i want in that place anyway. what a nightmare
 
#29
oh and i forgot to mention the next night, we playes in some small bar. I did not have my gear with me except a 4 string bass and a d.i box. This was the night i needed my rig but was not able to bring it because i was out of town all day. My guitar player running sound LOVED the fact i only had a di box. Says it sounded great out front. Agfain with that i dont know, because i did not have my wireless pack(which was in my rack case). so i was stuck with a 7 ft cord and a wedge monitor that made me not want to play bass anymore.

I never noticed how much i took my rig for granted till i tried that set up. never again.
 
#30
Stick with it. Now that your sound is more "pronounced" you're hearing things you aren't used to hearing. Some of this is good since you will cut through a mix better. But this is also a time to see if a small amount of EQ will smooth things out and get you to the place where you're confident in your tone.
 
#31
I have the same problem! With my Yamaha PB-1 I get "the hiss" through the FOH when I use the XLR-out and no hiss when I DI the bass from the Yamaha PB-1 line-out. I had thought the PB-1 had developed an issue as it did not do this in the past... till I tried my new SVT-7PRO XLR-out and it has the same problem with the hiss and is OK when DI'd using the line-out. Looks like there is a problem with the console or cabling and not the pre-amps. Not fully investigated yet.... will report back...
 

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