Musician Gear & Tech Discussion

Just thought I would share something that happened to me recently.

On the last few gigs, our bands subs were doing some funny things, in fact I thought the amp was going out, so the other night I pulled the pa out and decided to see what was up.

I found that if I pushed lightly on the gain on the sub amp it would work, when I would let go it would go in and out, so I just took some contact cleaner and really cleaned it out and then blew it out with some compressed air, and now its working great.

Just a complete brain fart for me, its done it the last few gigs, and what always happens is after a gig I just load the pa in the trailer and dont even think about it til the next time we set up.

Next time you get some buzzing or a short sound in your equipment, maybe try some contact cleaner on the pots before you send it to the shop.

Just made me feel real stupid that it wasnt the first thing I did, cause I was getting ready to pull the amp and take it to the shop and probably pay $100 just for a tech to clean the gain pots.

What cleaner did you use? I have some industrial contact cleaner in my shop but this crap will eat stainless I think.

Using power conditioners on everything, nothing except the conditioners ever get switched off. The sequential mode is used to "load " the various amps, mixers and other devices.
I'm thinking this should help prevent some filth issues as the majority of my contacts remain closed and all the amps are set to max, with volume control via the mixer.

George I just used some electrical contact cleaner, not sure the brand and then blew them out real good with compressed air, I turned the pot back and forth as I sprayed it, these are some QSC 1450 amps, I tandem two and use them for the subs, The pots are cheap plastic, Ive never really had problems with the metal type, I used peavey amps for years and they are indistructable to me, in fact, our bassist plays in another band and they didnt have subs, so I had an old CS 800 amp and some old FH1 enclosures, that they are using.

Speaking of diming your power amps, Im using a DBX Rack as a crossover and eq, and when I RTA a room it says to put the amps around 50 to 60% of the volume and not dime them. I always in the past just turned them all the way up, of course if thats working for you, fine, but Ive found by not opening up the main amps that we seem to have more headroom and it just sounds cleaner.

Im running a Yamaha 7000 series amp on the tops which are Yamaha 2x15s, for subs I run two QSC 1450s into two 1x18 bottoms. Im using an older QSC 1300 amp for our monitors. We have tow monitor mixes thru the amp, which drives a pair of peavey 1x15 monitors per side. But the mains we normally run the volumes at around 50%, of course we are way over powered for the venues we normally play, so that may be some of it.

Haley if you see this, you might comment on what volume level you run your power amps, Im just curious what others do on here.

Thanks John.

This begs more research and comment from the folks in the field.
If memory serves, I believe it was Carvin's Tech whom told me to dime the amps and make all volume adjustments from the board.
The 3-way towers I'm using combined with the 2-way center fill mains seem to be doing an admirable job if comment from our fan / audience base is the judge.
I have concluded that we will eventually need some subs especially outdoors.

You'll get a cleaner sound (if that's what you want) my pushing the mixer faders up and power amps down below 75% - it's all about signal-to-noise ratios. Lower input to amps means less signal more noise.

You'll get a cleaner sound (if that's what you want) my pushing the mixer faders up and power amps down below 75% - it's all about signal-to-noise ratios. Lower input to amps means less signal more noise.

U are right as usual, and I would like to add; It also depends on the system and how much gain you have prior to the amplifier. The level controls can be thought of as input attenuators. They do not limit the power available from the amplifier. With the level controls turned down the amplifier can still reach full rated output power, it just takes more drive level from your mixer to achieve it. Generally, you should set the mixer's individual channel sliders and master gain to 0 dB, then adjust the amplifier level controls to the desired sound level.

Good information.

I generally start with the individual channel faders @ 0

I'll play with this some. Though to be honest most everyone has said our sound was "awesome" so I must be doing something right.

George if it aint broke dont try to fix it.

Over the years I always just dimed power amps, but Im learning different. I think part of the problem was for years we tryed to play as loud as our equipment would allow us too, instead of being sesible about it, we always pushed things right to the brink of feedback and then cut it back slightly.

This DBX Drive Rack unit we are using has really taught me a lot, its one of the best devices Ive ever bought for a pa system.

I think trying to hit 0db attenuation, or unity thru out your signal chain is the key to good clean sound, as someone said if you overdrive the signal prior to the power amp section you will introduce noise or even distortion.

George if it aint broke dont try to fix it.

Over the years I always just dimed power amps, but Im learning different. I think part of the problem was for years we tryed to play as loud as our equipment would allow us too, instead of being sesible about it, we always pushed things right to the brink of feedback and then cut it back slightly.

This DBX Drive Rack unit we are using has really taught me a lot, its one of the best devices Ive ever bought for a pa system.

I think trying to hit 0db attenuation, or unity thru out your signal chain is the key to good clean sound, as someone said if you overdrive the signal prior to the power amp section you will introduce noise or even distortion.

Yep, a long time ago I was taught to seek unity gain from mic input through mixer, effects, and power amp for the cleanest signal. With my current setup that means the input gain setting for powered speakers is approx. 75%. When we used to use subs, the Crown sub amp was dimed, tops were 75%, and everything was fine tuned through an EV speaker controller/xover.

George I just used some electrical contact cleaner, not sure the brand and then blew them out real good with compressed air, I turned the pot back and forth as I sprayed it, these are some QSC 1450 amps, I tandem two and use them for the subs, The pots are cheap plastic, Ive never really had problems with the metal type, I used peavey amps for years and they are indistructable to me, in fact, our bassist plays in another band and they didnt have subs, so I had an old CS 800 amp and some old FH1 enclosures, that they are using.

Speaking of diming your power amps, Im using a DBX Rack as a crossover and eq, and when I RTA a room it says to put the amps around 50 to 60% of the volume and not dime them. I always in the past just turned them all the way up, of course if thats working for you, fine, but Ive found by not opening up the main amps that we seem to have more headroom and it just sounds cleaner.

Im running a Yamaha 7000 series amp on the tops which are Yamaha 2x15s, for subs I run two QSC 1450s into two 1x18 bottoms. Im using an older QSC 1300 amp for our monitors. We have tow monitor mixes thru the amp, which drives a pair of peavey 1x15 monitors per side. But the mains we normally run the volumes at around 50%, of course we are way over powered for the venues we normally play, so that may be some of it.

Haley if you see this, you might comment on what volume level you run your power amps, Im just curious what others do on here.

Just saw it John. I don't run my power amps full out because if I did it could blow my drivers! I back it off just a bit. I had the same problem with one of my QSC's a couple of years ago. My friend Barry went into the amp (down to the heatsinks) and changed those volumn knobs out. It freaked me out I would have never done that! This was just after I disbanded Cruise Control. I have not used my p.a. since then it has just set in the trailer in my garage. On June 9th we had a gig where Barry couldn't be there so I Brought my p.a. out and it worked better than ever. You guy's will here me talk about Barry a lot. He is a great friend and musical soul mate. We will ALWAYS be included in one anothers projects! We have been using his p.a. Allen and Heath Mixrack controlled via wireless laptop and run through $20,000.00 worth of state of the art line array gear! We basically put on the same quality show you will see at a major concert at a club level scale!

John when you set up your driverack did you go through the manual setting up all parameters. When we did mine we used the JBL settings suggested in the manual. We went through the wizard set up. I have RTA'd so many rooms since I first got this thing in 2005 I don't need to spectrum analize rooms anymore. I just find one that is close to the rooms I have stored about 40 or so and I almost always find one that is close. Those club owners hate it when I run the auto eq LOL!