I went out to local pawn shops with my bandmates to get a good amp I could use, and being electronics illiterate, my friend advised me to go with a PA instead. I bought a 300watt, 6 channel Peavey PA. It's old, 1980. I bought a set of fender PA speakers, 100w each for the PA.
Now, the problem is that when I try to play, the speakers cut in and out very often, like every couple seconds at least. It is kind of like rapid farting, if that makes any sense.
The speakers work through another PA, and I'm pretty sure the PA works too. Anyone have any help?
My first guess is that there is too much low-freq stuff from the bigger PA amp. Adjust the EQ to reduce the amount of signal below 100Hz and see if that helps.
-Laz
There could be a few different reasons for this. Without hearing it and testing this would just be somethings to consider and a WAG.
1. could be from the mismatched power rating between the power and speakers. Theres a big difference between rated, continuous and peak. if you over powering them they may have a breaker on them to keep from burning them out.
2. What Ohms does the power amp put out. example: 4ohms at 300 watts, 8 Ohms at 200 watts, etc. It needs to match your speaker rating also. If your Ohms don't match you'll have problems, anything from over heating the power amp to over heating the speaker coils.
3. It also possible that the amp has a power supply problem and can't keep up with the continuous or peak demand when its called upon. capacitors may be bad and can't hold and even current flow.
4. Bad cables into the mixer amp to even the speaker cables themselves.
5. There maybe a control on the mix/ amp that has a bad spot or burnt spot, maybe just has a lot of dirt and dust in them.
6. Someone not knowing what their doing could have changed a resistor, diode, potentiometer, or some other part that is not within spec's.
7. Speakers or the crossover in the speakers maybe bad or blown.
8. You could aslo be running beyond the peak limits of the amp which would create it to clip and cutout.
This are just a few things to consider on your Quest to trouble shoot the problem. Hope it gives you somethings to think about. Without testing it or hearing what it doing this is the best I can offer.
Joe
This is why I'm shaky on buying used electronics. Rather have new electronics and if need be, used instruments. If if there is a problem with something new, it should be under warranty. good luck.
It is a small world for metal fanatics. I welcome you fellow musicians, especially the metalheads!
I checked the Ohms, and they don't match up. The speakers are running at 8 Ohms, and the PA is 300w at 2, and 210w at 4. Also the PA that is currently powering the speakers is 8 Ohms.
Just how important is it for Ohms to match up? Is it possible for the system to work regardless?
Your friend should have checked this.... :-[
What you could do to check if it is an impedance matching problem is to connect the speakers to one channel output in parallel - effectively making them one 4 ohm 200 watt speaker. This would probably be a better match, see if it improves any.
Boomshanka is right. Run both speakers off one side of the amp. You will then have a 4 Ohm load, each speaker will get 105 Watts each. You could then run a pair of 8 Ohm Monitors off the other side (If it's 2 channel).
A very helpful site I go on is Scott's PA Tutorial. There are a lot of nice people on there who are very knowledgeable and will be happy to answer any questions you have. Just search for it on Google or Yahoo.
I have a bad feeling the real problem is that head. It's very old and probably has problems.
Correction- I meant to say if your PA head has 2 built in amplifiers, not channels. Sorry
This will sound weird, but one of the peavey sp2s I bought had a sound similar to what you are describing and it turned out that the bit of grey colored foam they put inside it (behind the dust cover near the vent holes at the back) had melted and jammed up where the cone goes around the coil (I think I've described this right?) I ended up 'surgically' removing the dust cover and using a syringe to drip wd40 (water dispersant) on the affected area to disolve the melted gunk, then carefully wiped it out...it sounds ok now.
