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Another dumb OHM question

Posted: Sun Apr 10, 2011 7:02 pm
by doomedfuzz
I have an Orange Rockerverb 100 head. 2x8ohm outs and one 16ohm out. I usually run a single Orange PPC412 that is 16ohm and have no issues doing so. Now my question: With this amp head, can I run two 8ohm cabs? Reason being, I want to run a full stack and I have an 8ohm Sunn cab and I have the opportunity to pick up another 8ohm cab cheap. Thoughts?

Re: Another dumb OHM question

Posted: Sun Apr 10, 2011 7:31 pm
by MEC
I haven't checked the schematic but if you have two 8ohm speaker outs you should be able to run two 8ohm cabs at the same time.

Re: Another dumb OHM question

Posted: Sun Apr 10, 2011 8:00 pm
by the Life Aquatic
no, u would need to run 2x16 ohm cabs putting both in the 8 ohm jacks. 2x16 ohm cabs will be 8 ohms. also it should tell u in the manual, i have a TT and i remember seeing something in the manual about how to hook up cabs to it

Re: Another dumb OHM question

Posted: Sun Apr 10, 2011 8:05 pm
by doomedfuzz
I didn't get a manual with mine, but I downloaded the PDF and it says NO do not do what I was wanting to. Oh well!!

Re: Another dumb OHM question

Posted: Sun Apr 10, 2011 11:55 pm
by MEC
I just checked the manual out and you guys are correct. :picard:

The only way to use two 412 cabs with 8ohm speakers is to rewire them in series making them 32ohms and then daisy chain them for one 16ohm load.

Re: Another dumb OHM question

Posted: Mon Apr 11, 2011 7:38 am
by Toonster
well he can use can use each 8 ohm cab on an separate output right?

Re: Another dumb OHM question

Posted: Mon Apr 11, 2011 10:23 am
by siamesegun
Toonster wrote:well he can use can use each 8 ohm cab on an separate output right?


No, those outputs are wired in a way that the cabs connected to them cannot have a net impedance lower than the rated value. Therefore, two 16 ohm cabs would halve the impedance to 8 ohms which is allowable. Attaching an 8 ohm cab to each output would lower the impedance to 4 ohms, which is lower than the output tranny is designed for and would prove damaging to the head.

Also important to note that a 16 ohm cab and an 8 ohm cab together would combine to an impedance of 5.333 ohms, which is still too low for the head.

Edit:

Check out this site for a bit more explanation and a calculator: http://www.bcae1.com/spkrmlti.htm
Also this: http://www.marktaw.com/recording/Electronics/OhmsAmpsandSpeakers.html