ohm question

[Empty Pockets]

I have 3 cabinets that i want to use 1 head to push. Two are rated at 4ohms, the other is 16ohm. What would my total ohm load be? The amp can be set to run at 8, 4 or 2. Thanks guys.

 

[i love everyone]

Re: ohm question

Assuming the cabs are all connected in parallel, it would be 1.777 ohms (1/Rtotal = (1/R1) + (1/R2) + (1/R3)), in which case you'd set the amp to 2 ohms. However the total wattage will not be shared equally; the 16 ohm cab will only receive 1/4 the power that the 4 ohm cabs receive.

 

[Empty Pockets]

Re: ohm question

Beautiful. Thanks a ton.

This is gona be heavy as fuh.

 

[Empty Pockets]

Re: ohm question

Beautiful. Thanks a ton.

This is gona be heavy as fuh.

 

[i love everyone]

Re: ohm question

Awww yeah; what kind of amp are you using? My Peavey Butcher is the only amp I've ever seen with more than 2 speaker out jacks. It has 4 but only goes down to 4 ohms.

 

[everdrone]

Re: ohm question

keep of the good work, glad u r gonna bring the EXTREME DECIBELS like me and my uber mayhem loud full stack rig like uncle jerr metal maniac. my full stack rig:

 

[Empty Pockets]

Re: ohm question

I got this 60's Univox for dirt cheap a few months ago... my avatar pic is the back of it, heh. It is working nicely as a pedal platform while i procrastinate on putting new filter caps in my 68 Bassman...whose cab will just have to run on whatever the two SUNN 4x12s don't suck up for now :smokin:

Charlie likes it.

 

[everdrone]

Re: ohm question

:beerchug:

 

[Empty Pockets]

Re: ohm question

Same question, except now I have two 16ohm 4x12s and a 4ohm 2x15. I tried to do the formula as shown but I am pretty sure my math is wrong.

Will post pix after I hear it.

 

[Empty Pockets]

Re: ohm question

Kept googling after my post... Found this:
http://www.sengpielaudio.com/calculator-paralresist.htm

Kinda slick. It says I have a 2.666 load. Heavy...

 

[CTN]

Re: ohm question

for loads in series, Rtotal = r1 + r2 +..... + rn

for loads in parallel, 1/Rtotal = 1/r1 + 1/r2 + ... + 1/rn

Generally, the parallel formula works out to Rtotal = (r1*r2*r3*....*rn)/(r1 + r2 + ... + rn)

 

[the guy who invented fire]

Re: ohm question

This thread makes me feel very bad for your amps...

Be careful...


Sent from my iPhone using Tapatalk

 

[Empty Pockets]

Re: ohm question

Oh come on... These are all safe loads, right? As long as the resistance of the cabs isn't bigger than the amp can handle, right? Head is 2 ohms so 2.666 should be safe... Yeah?

 

[CTN]

Re: ohm question

Think of the various taps (2ohm, 4ohm, 8, 16) as "minimum impedance". If you're using an 8ohm tap, your speaker load should be 8 ohms or above - so 16ohms is ok, but 4 ohms is not (in practice though, the actual impedance of a speaker or set of speakers can fall a wee bit below the tap ratings or the specified impedance rating printed on the speaker label, but that's just a technicality).

In any case, mismatching upwards like I said, is ok, but you will experience a slight loss of volume/power.
Mismatching downwards will burn up transformers.

Best is to just not mismatch at all.

 

[Empty Pockets]

Re: ohm question

That's what I thought. Thanks dudes. This is of course just a temporary situation... I will soon have more heads to push these cabs with

 

[the guy who invented fire]

Re: ohm question

Oh come on... These are all safe loads, right? As long as the resistance of the cabs isn't bigger than the amp can handle, right? Head is 2 ohms so 2.666 should be safe... Yeah?

Amp set to 2, total load of 2.66...you'll be fine



Sent from my iPhone using Tapatalk

 

[the guy who invented fire]

Re: ohm question

Think of the various taps (2ohm, 4ohm, 8, 16) as "minimum impedance". If you're using an 8ohm tap, your speaker load should be 8 ohms or above - so 16ohms is ok, but 4 ohms is not (in practice though, the actual impedance of a speaker or set of speakers can fall a wee bit below the tap ratings or the specified impedance rating printed on the speaker label, but that's just a technicality).

In any case, mismatching upwards like I said, is ok, but you will experience a slight loss of volume/power.
Mismatching downwards will burn up transformers.

Best is to just not mismatch at all.

"Mismatching down" is not a guarantee that you'll damage the amp.

It all depends on how far down (or up for that matter!), how long, how hard you push it and frankly what the amp is where talking about.


Sent from my iPhone using Tapatalk

 

[Empty Pockets]

Re: ohm question

Think of the various taps (2ohm, 4ohm, 8, 16) as "minimum impedance". If you're using an 8ohm tap, your speaker load should be 8 ohms or above - so 16ohms is ok, but 4 ohms is not (in practice though, the actual impedance of a speaker or set of speakers can fall a wee bit below the tap ratings or the specified impedance rating printed on the speaker label, but that's just a technicality).

In any case, mismatching upwards like I said, is ok, but you will experience a slight loss of volume/power.
Mismatching downwards will burn up transformers.

Best is to just not mismatch at all.

So just a thought experiment here... Say you have a very loud amp with adjustable ohm loads and you want less power for a smaller gig. Could you set the head to 4 or 2 ohms and push a 16ohm cab?

 

[MetalManiac]

Re: ohm question

'resistance' butthole..'resistance'. :13:

 

[MetalManiac]

Re: ohm question

But anyway, I know you are a drone/Stoner dude with multiple cabs and a buttload of cabs that who the hell knows what DC resistance of ...or "oHms" as you put it.
I wouldn't worry about it. What have you got to lose anyhow?
Acxtually thouhg...do not dick around with impedance. No, whatever you were aksing, no.