DESPERATE for help with audio problem

[Julia]

Hi, Friends. I hope no one will mind my posting about this here. I have gained such good knowledge from this board regarding recording issues (elementary school music teacher who records various all-original...written by me...programs), that I was hoping the experts would not mind my asking this question here, since I'm really desperate.

We are about to do a school-wide program (just 200 kids, but...quite a venture)...

I recently bought a brand new Behringer powered mixer. Long story, not important, it finally arrived (backorderd through the entire summer), and it sounds horrible. Brought it to my local music store owner, and he agrees...sounds awful...he called his Behringer rep and he said he thinks it must be faulty, because he has yet to hear bad things about this new mixer. Okay. We sent it back. No big deal. Inconvenient, but not the end of the world.

Next move? Buy a different mixer. Fine. I buy a Soundtech PMX10. Great. Sounds great in the store when we try it out. Costs $200 more than the Behringer, but we are so sick and tired of audio problems, we bite the bullet (I eat the extra cost) and buy it. Last night I'm in the gym until midnight trying to make it work. What happens? Great little mixer, but there is some sort of limiter or something (that's not the right term, I'm sure) in it (I'm guessing after 6 hours of trying to get it to work), because it just peaks out constantly, (and no, I'm not running really loud stuff through it.) I run a CD player into the "tape in" or into a channel to provide musical accompaniment with my original orchestrations, and I run the soloist's microphones (in this case this year we only have 3 soloists), and that is all. Period.

It just pops pops pops. If I could try to give you an example, I'd say...say you sing a long "ah"...like this:

aaaaaaaaaaaaaaaaaaaaaaahhhhhhhhh

What you hear is this:

ah --- ah --- ah --- (with pops in the middle that sound like something is shorting out or something like that.)

I don't know how to explain these things, but...maybe you get the idea. Anyway, I'm pulling my hair out and need this to be fixed by 11 today.

Can anyone offer any suggestions/guidance/help?

Thanks a million.

Julia

[Garry Sharp]

Julia

It's not necessarily a mixer problem. People here will need to know about the whole set up before they can help, so it would help if you could post:

What sort mic's you are using? (Brand etc. - they may be the problem).
How you are connecting them - which inputs
Where you are setting the gain control (rotary knob near each input)
Where you have each channel fader (slider) and the master fader set
Which outputs are you using and what sort of amplifier / speaker set up is it going into?
Does the CD playback sound OK?
Have you tried plugging headphones in and listening on those?

I'm sure you'll get some help quickly

[Blue Bear Sound]

Yes -- need more details... then we can provide more suggestions....

[Julia]

Thank you.

I'm using all (3) Shure SM-58 mics.

It's a stereo amp, and I go from the main outs (one from A, one from B) to the main speakers (which are Sunn 100 watt speakers, 8ohms.) I go from the monitor outs (in the back) into two unpowered monitors.

The mixer is a SoundTech PMX10, with three power amps.

The CD player is fine, but I did try others to troubleshoot. We've used this same set-up (and same CD player) for three years now.

The only new piece of equipment we've never used is this mixer.

We do have long wires...50 feet, I believe...because I go from the speakers (which are on stage) down to the front of the stage (out a ways) from where I conduct the students. I only use about 25, though, I suppose. The rest remains coiled.

I have a heavy duty extension cord plugged into a grounded outlet. I did try several others to see of that was the problem, too.

I troubleshot everything I could possibly think of until midnight last night. COuldn't fix it. I just read about limiters online, and thought that maybe the limiter in the mixer is the problem, but have no earthly idea how to reset an overly sensitive limiter.

I did try not turning the gains (control levels) up very high, but gosh I need SOME sound. The need for amplification is the whole reason I put up with these technological issues (which cause me great stress, by the way...in case you couldn't tell.)

Thanks for any guidance you might have to offer.

Julia

[Blue Bear Sound]

For one thing.... the CD player shouldn't be connected to TAPE IN.... those are a "Send" for input INTO a tape machine ONLY.

You want to connect the CD player to the TAPE OUT - which is the equivalent of a LINE IN....

That right there could be the cause of all your problems so try that first and see....

[DonF]

Um, Bear, wouldn't something marked "TAPE IN" be an INPUT? (I looked at the block diagram, and indeed it is in this case.)

Julia, you don't by any chance have phantom power turned on, do you? Could cause problems depending on what kind of cables you're using for the microphones.

Also, be sure you don't have the main amp configured in "bridged mono" mode. The PMX10 has a switch for this, I think.

Edit: It's also possible that you've fried your 100W speakers by hooking them up to a 200W (per channel) amplifier.

[chessrock]

Originally posted by Blue Bear Sound
For one thing.... the CD player shouldn't be connected to TAPE IN.... those are a "Send" for input INTO a tape machine ONLY.

You want to connect the CD player to the TAPE OUT - which is the equivalent of a LINE IN....

That right there could be the cause of all your problems so try that first and see....

[Blue Bear Sound]

Originally posted by DonF
Um, Bear, wouldn't something marked "TAPE IN" be an INPUT? (I looked at the block diagram, and indeed it is in this case.)

Well -- i've seen many Tape SENDS/RTNs labelled inversely... where the TAPE IN is "to tape inputs on tape machine..." (ie, a SEND) -- while the TAPE OUT is "from tape outputs..." (ie, a RETURN)

But yes -- whatever the block diagram says for that particular unit is probably correct....

OTOH - I once accidently miswired a tape deck on my home stereo and gotten similar symptoms to what she described - which is what made me consider the possiblity in her case...

[TexRoadkill]

Disregard Bear. He has apparently taken a trip to bizarro world

A limiter is most likely not the problem but if you can find out how to turn it off then that would let you know if it is the problem. Check the manual and turn it off.

Plug in a pair of headphones to see if the problem is there also. If so then you can eliminate the power amp and speakers as part of the problem.

If the problem happens with the CD player and mics then it's not a cable issue.

If none of the above worked I would guess you have another faulty mixer. That is the problem with cheap gear since you are usually the first person to ever turn it on. I would recomend getting a Mackie, Soundcraft or Yamaha if you can afford one. In my experience they are much more reliable.

One I thing I noticed is that you hooked up the monitor outs to unpowered monitors. Are you hearing anything through them? Usually the monitor outs on a powered mixer are not actually powered and require another power amp or powered monitors. Maybe yours does have power there but that is unusual. This probably isn't related to the #1 problem but it may become problem #2.

[mixsit]

I would try it with just one piece at a time -one speaker, to each output, and try it with each speaker and each speaker cable if need be. Any one of them shorting out could be dragging the system down.
Or maybe you could get the dealer to help with checking the mixer out. It is possible you still got a bad one.

[Blue Bear Sound]

Originally posted by TexRoadkill
Disregard Bear. He has apparently taken a trip to bizarro world

Could be...! But it would be hilarious if she switched them and it solved the problem, eh?!?!

[PapillonIrl]

Originally posted by Julia


It's a stereo amp, and I go from the main outs (one from A, one from B) to the main speakers (which are Sunn 100 watt speakers, 8ohms.) I go from the monitor outs (in the back) into two unpowered monitors.

Those Sunn speakers are not powered, are they ? If so that could be the problem. The desk has a built in amp, so you don't need another. Just a thought.

Nathan

[TexRoadkill]

Originally posted by mixsit
I would try it with just one piece at a time -one speaker, to each output, and try it with each speaker and each speaker cable if need be. Any one of them shorting out could be dragging the system down.
Or maybe you could get the dealer to help with checking the mixer out. It is possible you still got a bad one.

I would do that if the problem doesn't exist when listening through headphones.

Bear- But that wouldn't explain why it does it with mics also (which she didn't actually specify but it sounds like that is also the problem).

Troubleshooting these types of things is much more fun with a few thousand people out in the auditorium and a client looking over your shoulder.

[Blue Bear Sound]

Originally posted by TexRoadkill
Bear- But that wouldn't explain why it does it with mics also (which she didn't actually specify but it sounds like that is also the problem).

True - unless it's wired strangely across the main outs... (I haven't seen a block diagram for this mixer, so I have no idea!)

[mixsit]

Originally posted by DonF
Um, Bear, wouldn't something marked "TAPE IN" be an INPUT?

(I looked at the block diagram, and indeed it is in this case.)...

And that's the only way to tell for sure on some audio gear. It's been done. 'Yea, 'Tape Out' is where you put the 'outs' from your tape.' 'Tape Ins' connect to 'Tape Ins' on the other end. Made perfect sense in someone's world. Asinine.

[Julia]

Thank you all for taking the time to try and guide me through a troubleshooting process.

I took the mixer back to the store, it cracked for exactly 2 minutes, and then it stopped, and it hasn't happened since. Used the mixer for our entire rehearsal this afternoon without problems. Sigh. Who knows what occurred last night.

I will respond to a couple of issues raised...

Yes it does have a power amp specifically for the monitors. I did go into the stereo channel instead of the "tape in" this afternoon. I suppose that could have made a difference, but once again it would not explain why this occurred with mics last night as well.

It seems like a nice mixer, by the way. Oh, I know Mackie is a better choice, but hey...we're talking about a small Catholic elementary school where 20-year veteran teachers still make $20,000. Talk about a lack of budget. I had to beg, borrow, and steal (almost, but not quite) this mixer.

Our school is near a hospital....actually there is also a second hospital about two miles on the other side of the school as well...and so we were wondering if last night there were conflicting issues of some sort. I just don't know. It worked today...but of course I won't sleep until the project concludes on December 7th, fearing all the while that we'll lose our sound in mid-show. If that happens, there will be a whooooooooole lot of precious little sad faces of children who have worked really hard to produce a really awesome production.

And from them...and me...I thank you all for extending yourselves to try to assist me with our audio issues today.

Wishing you all a great weekend,

Julia

[Jeroleen]

The intermittent sound seems like a cable problem. Did you change the mic cable to see if it was shorting out. ALso, is there a detachable power cable that might be loose. I hope you get your equipment working but, either way, I learned something here. If you want responses on this site, use a female name and the word desperate. Everyone will notice (just kidding).