Implications of running below powered mixer ohm rating.....and why has it worked?

[duderanch]

Hey guys - so I know most powered mixers are rated at 4 ohm min....but just recently started taking a look at this. What has intrigued me is we have been running a peavey mixer (don't have model right now) with both monintors and mains for years, running the monitor output below the 4 ohms...with no real noticable problems. Granted, it was totally by mistake and out of ignorance, but in doing the research now, I'm curious why we never blew it up? Obviously, glad, but just curious....and wondering if we can/should keep doing it or if it's just dumb and we were/are lucky. We typically run at least 2 8 ohm wedges and 2 16 ohm hot spots....but sometimes 3 wedges and one of the hot spots. What say the experts? Dumb, stop doing ASAP, just lucky, keep up, etc. Thanks!

 

PS - one thing I am wondering is the main side has recently gone caput! It fades in and out at random so we taking it to repair shop. We never put less than 4 ohms in the main, but i wonder if it could somehow be related? Note - This set up has been used in club type settings for ~ 7 years, so it's not as if we've been doing a short time.

[dboomer]

I can speak to Peavey products as I was product manager for a number of those products. They "will" work fine when loaded at 2 ohms ... But ... They are not rated at 2 ohms because they will not pass the UL requirements when done that way.

 

So what happens when you do it? Well you significantly shorten the lifespan of the unit in the same way as you would just about any other item (like a car) if you ran it at the redline for its entire life. You'll get more "Watts" but it will be at the cost of some sonic degradation because the current limiters will be kicking is sooner.

 

Running a pair of 8ohm wedges and a pair of 16ohm hot spots probably looks like a 3ohm load to the amp, so you'll probably get away with that for a long time, especially if you aren't running it hard and into limiting much.

 

Me, I wouldn't want to run that way as standard practice.

[duderanch]

Great input! (no pun!) Yes, after finally finding all of this out, I am going to recommend we run an external amp for the monitors.

 

Do you think that the other side of the amp going - main amp....can be related in any way? Although intuitively it may not make sense...at least to a novice.....I'm wondering if there is some explanation. Also, any clue what the "going in and out" issue is - what is normally the cause and is it fixable within reason or new amp time? What we may just do in the meantime is use the mixer part of it and external amp as we don't have a compact passive mixer. Thanks!

[wesg]

"going and out" - unless the monitor amp is doing this also, it's probably not related.

 

How old is this amp? If it's 10 or 15 years old, chances are it can be fixed relatively easily if you have a good repair tech on call.

 

Wes

[Dogoth]

As dboomer stated, Peavey amps are built beyond spec so as to make for a reliable product (imagine that . That said, he is also correct in that you are probably putting undue stress on that amp channel. It's all about current. If you aren't driving it anywhere near it's rated output you aren't drawing more than the max rated current from the output stage (I.E. you could run a 2 ohm rated 1000 watt amplifier at 1 ohm if you never ask it to deliver more than 300 to 500 watts - I NEVER would do this nor do I recommend it). Music being highly dynamic, It only takes one good spike (some low feedback for a second or so) to excede this limit and kill the outputs of your amp.

 

Basically, you've been lucky and your idea of running a separate amp for monitors is a good one. Do so soon.

 

I would doubt the main channel fading in & out is related unless you have used this channel for you're monitors sometime in the past (some powered mixers allow this through patching).

 

Get an additional amp, fix the mixer and all should be good with the world.

[duderanch]

Thanks for the input! Well, the update is we have the amp now to see if it can be repaired. You can't find anyone to repair these anymore!!! I think we are on our 3-4th place before we found somebody who has a guy that works on them. I will say we really don't push the system hard at all which is probably why we've been lucky with it. What's odd is the non monitor side going. We've lost two powered mixers in about a 3 month period. Thanks again!

[abzurd]

When I read the title I said to myself "Because it's a Peavey I bet", then I opened the thread to confirm. This is how "old school" Peavey did it. They knew a large percentage of buyers had no clue and were just going to plug things in and let er' rip then toss it in the trunk (no case) after the show. With that target audience the stuff had to save people from themselves and be built like a tank, inside and out.

 

I'm not sure the same could be said today because Peavey has to compete with disposable "B"rands and the easy access to everything versus having to buy to whatever the local mom & pop was selling..... which was almost always Peavey.

[duderanch]

ahhhhhh.......that's very insightful and helpful and makes perfect sense! It's exactly what we were doing! I learned about Ohm's after the fact and started to realize we were doing it wrong.....but certainly before then, your description is totally what we and I'm sure most other bando's were doing! Great insight! I still haven't been able to figure out what is causing the "in and out" of other side....and we are trying to get it repaired.....but very difficult to find repairman "nowadays". As you say, they are treated like throwaways!

 

What is interesting....and I'm sure very much related to your comment.....is that we have an older PV amp....the one refenced in this thread....and yes, it is built like a tank and has worked flawlessly....despite us overdriving it......for 10+years....until this recent issue. BUT....we had another PV amp that we picked up and started using because it was much lighter......that thing lasted about 3 years and so far we've been told it's not repairable. Aligns totally with your comments.