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had a big problem with new rig at rehearsal last weekend. (pics)

B

biff malibu

Apr 5, 2006
494
3
Dallas, Texas
www.myspace.com
#1
here is my rack.

biff malibu said:
bassrack-1.jpg
Click to expand...


sounded GREAT for about 15 minutes. with the volume knob at 10 o'clock, the mackie went into protect mode for about 20 seconds and came back again...and did this over and over. :mad:

the top of the mackie was hot to the touch, the internal fan was running smoothly, so today i removed the blank slot under the furman and moved the tuner and RBI both up one slot off the top of the mackie and i now have a 4 inch metal desktop fan about 1/2 inch from the mackie's intake fan in the back of the rack.

like so:

movedrack.jpg


rackfan.jpg


should this solve the problem?
 
#7
biff malibu said:
i thought about that, but the mackie's overload light never came on, so i kind of ruled that out. :hmm:
Click to expand...

I'm going to go with Junior here. I've measured the output of my RBI at full gain and it exceeded 17 volts. Isn't the input sensitivity of the Mackie around .775 volts? I usually run the output of the RBI around 10 to 11 o'clock with a 500 watt amp, and it's plenty loud.
 
#15
The RBI doesn't have an overload light. This is not a temperature issue, you are just overloading the input on your power amp. Turn the pre-amp down and your power amp up, 10 o'clock is part of your problem. Set the power amp to near wide open, more like 3 o'clock, then use the RBI to set your actual volume/spl. That will go a long way towards getting what you need out of that rig. If you want that full-blown distortion sound all the time, don't expect to get that out of an RBI. If you just want it to simulate a couple tubes gettin' nice and hot, then it is still the pre for you.

The techie geeks can better explain why, but your power amp will actually be working less hard running it this way.
 
#17
Having the blend knob to 100% wet does mean a significant mid scoop, which in turn means that you have to crank the output gain a lot higher to get the same perceived volume, which in turn contributes to overloading the input of the power amp.

One other way to get more distortion out of the RBI is to slam its input with a boost or overdrive pedal. That kind/amount of boost will not harm the RBI or cause it to shut down (we're talking maybe 1 volt signal level when boosted, compared to the 17 volts of the maxed RBI output).
 
#18
bigfatbass said:
The RBI doesn't have an overload light. This is not a temperature issue, you are just overloading the input on your power amp.
Click to expand...
Overloading the input will cause distortion, but it won't make the chassis hot or cause the protect mode to kick in. That's the result of either insufficient air flow or too much current draw. If airflow is ruled out then you have to look at the load impedance, bad speaker cabling or improper bridging.
biff malibu said:
maybe i'll take a look at that then. do you guys think it would have anything to do with some voltage/etc/whatever from it being run through a furman power thing?
Click to expand...
It could. Power amps don't need 'conditioning' or voltage regulation, and devices incapable of delivering adequate current to the amp can cause them to overheat.
 

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