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why wont my peavy markiii not power 2 4x10 cabs

joel morgan

joel morgan

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Apr 15, 2017
6
0
#1
black magik? sorcery? ill try anything cus im friggin baffeled. im running a Peavy markiii Centurion , 130 watts @4ohms, two speaker outlets in paralell(that is what it says on the back of the amp) if i run it into my avatar 4x10 (4 ohms) and an Ampeg 4x10 (4ohms), in theory, everything should be dandy, aye? well , sadly not so. the heat kill kicks in, the amp is hot enough to light a joint on...when i run either 4x 10 individually it gets HOT, but doesent shut off after an hour set. played the head through my drummers Hartke 4x10(8ohm) no heat....now that you have some facts, would it fix the problem to rewire the cabs to 8ohm, provided the speakers will handle it? is there a simpler fix? could it be the crossover in both cabs? they both have horns... oh yeah , if i split the signal off my pedal board and run two amps it runs cool enough to not trigger the heat kill , but still heats up. can any one help me withthis? i really love my Markiii , in fact , it love to get two more...
 
#4
Unfortunately, everything is not dandy. Your amp is rated for a 4 ohm minimum load. Your 2 x4 ohm cabinets present a 2 ohm load to the amp. You are lucky your amp did not fail.

[edit for typo]
 
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#6
thanks LZ , read my whole post so you can understand my question. because my rudenmentary understanding oh Ohms tells me that my amp shouldnt get hot when im running 1 4ohm cab the head is still running hotter than it should ...but feel free to take every opportunity to be a smarmy know it all...
 
#14
Joel, firstly welcome to TalkBass. You've already started off badly with the smarmy comment. May I humbly suggest that you cut out the attitude and instead listen to the folks that are trying to help you.

An amp of that age could well be blocked by all the crud that is has sucked in over the years. If it's like others of the Mark series you can carefully remove the back and very carefully vacuum out the stuff that's in there. You might need to use a soft paint brush to dislodge the stuff. Once that is done you will find that your amp will run cooler. Follow the advice of @agedhorse - He designs amplifiers for a living and we are lucky to have the benefit of his advice. :)
 
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#16
Your question is -- why won't your amp run 2 4x10 cabs? So, that one has been answered -- because a 2 ohm load will fry your amp (hope you didn't damage it). But, you have a second question-- why is your amp so hot, when running 1 cab? Although it may seem hot (and I don't know what you consider hot), it is probably still within the allowable specs. The reason your friends 8ohm doesn't get as hot is because it is a lesser load.

Edit: didn't see BassmanPaul's advice. Good idea to clean that thing out, first.
 
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#17
joel morgan said:
black magik? sorcery? ill try anything cus im friggin baffeled. im running a Peavy markiii Centurion , 130 watts @4ohms, two speaker outlets in paralell(that is what it says on the back of the amp) if i run it into my avatar 4x10 (4 ohms) and an Ampeg 4x10 (4ohms), in theory, everything should be dandy, aye? well , sadly not so. the heat kill kicks in, the amp is hot enough to light a joint on...when i run either 4x 10 individually it gets HOT, but doesent shut off after an hour set. played the head through my drummers Hartke 4x10(8ohm) no heat....now that you have some facts, would it fix the problem to rewire the cabs to 8ohm, provided the speakers will handle it? is there a simpler fix? could it be the crossover in both cabs? they both have horns... oh yeah , if i split the signal off my pedal board and run two amps it runs cool enough to not trigger the heat kill , but still heats up. can any one help me withthis? i really love my Markiii , in fact , it love to get two more...
Click to expand...

You can safely run ONE (1) of your 4 ohm cabs with it because your amp is rated for a 4 ohm minimum load. Putting two of our 4 ohm cabs on it runs a 2 ohm load which will badly overheat and can melt an amp. You have been super lucky. Don't try it again.

Unfortunately there is no way to rewire a 4 ohm cab to make it an 8 ohm cab. You can rewire it to make it either a 16 ohm cab or a 2 ohm cab, but that's it. If you want to run your two cabs on that amp, you will need to get a serial/parallel connector box and hook them up in serial. First cab goes into the amp. Serial box connects to the output of the first cab and you plug your second cab into the serial connector box. That will give you an 8 ohm load which won't damage your amp.

HOWEVER, that will also cut your watts of output down to 65-watts because you've just doubled the ohms load on it. So that would deliver 32½ watts to each cab. I doubt that would work very well. You might be better off getting another mark III amp and slave it to the first. That way you would send 130 watts to each of your 4 ohm cabs.

Serial connection box will be the cheapest fix, but you may not have enough watts to get very loud if you need loud. The cabs will handle it just fine but 65-watts into each cab isn't a lot of watts if you need to play loud.

If you decide to get a second amp, you can slave it to the first amp by running a Y-cord out of your effects-out (send), running a short cord back into the effects-in (return) of your first amp and run another cord off the Y-cord into the effects-in of the second amp. That bypasses the preamp of the second amp and just uses the power amplification circuit of the second amp. You'll still need to adjust the master volumes separately on them, but any EQ change you make to the first amp will carry through to the second. I used to do this running an Eden Nemesis RS400 as the master and slaving a GK250bk amp to that. Was kind of funny to hear an GK amp sound like an Eden amp.
 
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#18
joel morgan said:
black magik? sorcery? ill try anything cus im friggin baffeled. im running a Peavy markiii Centurion , 130 watts @4ohms, two speaker outlets in paralell(that is what it says on the back of the amp) if i run it into my avatar 4x10 (4 ohms) and an Ampeg 4x10 (4ohms), in theory, everything should be dandy, aye? well , sadly not so. the heat kill kicks in, the amp is hot enough to light a joint on...when i run either 4x 10 individually it gets HOT, but doesent shut off after an hour set. played the head through my drummers Hartke 4x10(8ohm) no heat....now that you have some facts, would it fix the problem to rewire the cabs to 8ohm, provided the speakers will handle it? is there a simpler fix? could it be the crossover in both cabs? they both have horns... oh yeah , if i split the signal off my pedal board and run two amps it runs cool enough to not trigger the heat kill , but still heats up. can any one help me withthis? i really love my Markiii , in fact , it love to get two more...
Click to expand...

Light a joint and wait for it to cool down.

Just kidding! What everyone else said.
 
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#19
One more thing, just because your amp has two speaker jacks and is rated at 4 ohms does not mean that each jack can be connected to a 4 ohm load. That means the total load for both jacks together cannot be lower than 4 ohms. Those two jacks are in parallel with each other, both driven by the same output section. The reason two jacks are provided is to make it easier to connect two 8 ohm cabinets at the same time. Because two 8 ohm loads add up to 4 ohms, that would be just fine. Unfortunately, with 4 ohm cabs, you can only use one at a time.

Raf
 
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