I have checked all the FAQ's(OHM question)

[Mooch]

Ok so I have looked at - dont know how many FAQ's on the net about ohms but I think my question may just be too simple or I'm an idiot. Probably just an idiot.

Here is my question. You have an amp say it puts out 300 watts at 8 ohms. It has 2 speaker outs on the back. You have 2 separate 8 ohm cabs.

Here are my two questions. If you hook up one cab to one speaker out and then hook the other cab to the other speaker out is everything still 8 ohms? Also, does the amp simply divide the power in half to each speaker out? Like 150 watts to each?

Seems simple enough right? But, no where can someone find a simple answer for this crap. Its always daisey chaining or different ohm cabs. Never 2 of the same thing with both speaker outs.

I have had mine hooked this "separate" way forever because it seems like the best way in my tiny brain, never had an issue. Just want a clear answer is all.

[jeffkew]

If you have an solid state amp that puts out 300 watts at 8 ohms, it most likely puts out something more like 450 watts at 4 ohms.

Two 8 ohm cabinets plugged into the speaker outs on the back of the amp create a 4 ohm load - that's just the way ohms work!

So if your amp did provide 450 watts at 4 ohms, 225 watts would go to each of the speaker cabinets.

If you plug just one of the cabs in, the load will be 8 ohms, and so that cab will get 300 watts.

BTW, plugging the two cabs into the back of the amp almost always has the same result as daisy chaining from one cab to the next - the two 8 ohm cabs will yield 4 ohms either way.

Also, BTW, this only holds true for solid state amps - not tube amps.

Hope this helps!

[bobcruz]

The amp owner's manual will explain all about this without speculating about wattage or solid state vs. tubes. If the manual is missing or it's an old model, the manufacturer's websites often have them archived.

[Mooch]

Ok so makes a whole new set of questions lol. First, I was just throwing the 300w out as an easy number. I now own a HA3500 and its 350w at 4 ohms and like 225w at 8(I think).

I am getting a SL600 soon(on order) and thats like 350(again I think) at 8ohms. I just upgraded speakers in my 4x10 cab to 150w 8 ohm speakers wired in series/parallel. The old cab was rated at 240w at 8 ohms, speakers said nothing of what they were rated at.

Is the new cab setup with the 4 150w speakers now 500w? That's something I was curious about or is it divided because of wiring to 300w? This gets nuts for my brain to tackle. Math isn't my strong suit. I'm a history guy.

Also, since this makes my cabs from 8ohms to 4ohms hooking them this way is it bad for the cabs?

[BigOldHarry]

It rather depends on the amp - post the make/model of the amp for us. If it is a stereo amp with discreet power sections rated *each* at 8 ohms, then hooking an 8ohm cab to each channel will be running at 8ohms *each*.

Much more likely is that this is an amp with two non discreet outputs, so if you put two 8 ohm cabs on it, it will be operating at a 4 ohm load. Your amp owners manual will have a rating for output at 8/4 and perhaps 2ohms (if it is rated to handle that load).

Now, if you daisy chain speakers, you are halving the rating - and thus doubling the load - - So 8ohm cab daisy-chained to an 8ohm cab = 4 ohm load.

here's a good discussion I found on this subject on the Vox web site - found using the miracle of this thing called "Google":

http://www.voxamps.com/forum/topic.php?id=1675

[coreyfyfe]

Originally Posted by jeffkew

Two 8 ohm cabinets plugged into the speaker outs on the back of the amp create a 4 ohm load - that's just the way ohms work!

Assuming the two outputs are in parallel, which on a modern solid state head they should be. Some old tube amps have the outputs wired in series but they're much less common than parallel outs.

[Mooch]

Well I understand my Hartke head after turning off the idiot switch and looking at the manual. But, the Genz Benz SL600 thats on order the back says doesnt say the speaker outs are a certain ohm rating like the Hartke. They simply say paralleled jacks minimum 4ohms.

Whats this mean? And hey I used google to find this Thanks for the help so far guys, just want to be super sure I have no worries with this new setup and you guys know everything.

Anyone got an answer to the 4 150w 8ohm speakers question? Whats the cabs rating now? dummy me thinks 500watts.

[jeffkew]

Originally Posted by Mooch

Ok so makes a whole new set of questions lol. First, I was just throwing the 300w out as an easy number. I now own a HA3500 and its 350w at 4 ohms and like 225w at 8(I think).

I just looked at an image of the back of an HA3500, and I think I might sort of understand what might be part of you confusion. The two speaker jacks are each labeled "8 ohms" - but the only thing you really need to know with this amp is that you should not plug in speaker(s) lower than 4 ohms total into the amp at one time. Two 8 ohm cabs plugged into the back of this amp will work fine, and each cab will get 175 watts. It doesn't matter, in this case, whether you daisy chain the speakers or plug them both into the back of the amp.

[jeffkew]

Originally Posted by Mooch

Anyone got an answer to the 4 150w 8ohm speakers question? Whats the cabs rating now? dummy me thinks 500watts.

Well, I'm not sure I totally understand how you've got the speakers wired, but, in general with a 410 cab, just multiply the wattage of an individual speaker by 4 and, in your case, you get 600 watts. For example, the SWR Goliath IV 410 cabs have (4) 200 watt speakes for a total of 800 watt power handling.

[jeffkew]

Originally Posted by Mooch

They simply say paralleled jacks minimum 4ohms.

Whats this mean? And hey I used google to find this Thanks for the help so far guys, just want to be super sure I have no worries with this new setup and you guys know everything.

Just make sure that total impedance of all the cabs you use with the Streamliner is not lower than 4 ohms - otherwise you will likely fry your new amp. Because the jacks are in parallel, it doesn't matter if you use both the jacks or daisy chain from one speaker to the next.

[coreyfyfe]

Originally Posted by Mooch

They simply say paralleled jacks minimum 4ohms.

The jacks are in parallel, the minimum impedance is 4 ohms. If you use more than one cab, make sure they will be 4 ohms minimum if connected in parallel (ie one 4 ohm cab, two 8 ohm cabs, four 16 ohm cabs, etc).

Originally Posted by Mooch

Anyone got an answer to the 4 150w 8ohm speakers question? Whats the cabs rating now? dummy me thinks 500watts.

The cab should be 600 watts total and with four 8 ohm speakers wired in series/parallel the total impedance will be 8 ohms.

[Mooch]

Ok guys I have seen the light! Thanks for all your help sorting this out for me. Now i can pass the knowledge on to the countless others who don't get this.(guitards) Here's to a new rig!