5150 Newb Questions....ohmage....

[C_F_H_13]

For as long as I can remember, I've always ran heads and cabs at 16 ohms (providing it was available). Well yesterday a friend of mine suggested I run my 5150 at 8 ohms, use BOTH outputs and run my Marshall 1960a cabinet at 8 ohms stereo.

Does this make sense? Ohms is one of those thigns I still havn't grasped yet.

 

[Downtime]

I´m using single-output 8 ohms for many years now and things work well

 

[ochants76]

don't use both outputs...it is pointless...and it isn't "stereo" so don't run the marshall cab on the stereo setting.

 

[MetalWorks]

Some companies like Krank do recommend connecting a single cab this way for the most power. Im looking at it like 120 watts into 2 75 watts speakers is going to be more powerfull than 120 watts going into 4 75 watt speakers.

So each output is independantly providing 120 watts to 2 speakers.

As opposed to 1 output putting 120 watts to 4 speakers.

Will you notice any difference?

Maybe, but probably not enough to go through the trouble of it.

I would keep the head on 4 ohms and run it into the cab mono with one speaker cable.

And from what I am aware of, you should never connect an ohm load higher than what your amp is switched to.

Dont set the head to 16ohms and plug in a 4 ohm cab because it can damage the head.

You are better off either matching the cab or leaving the head on 4ohms.

My friend kept his 5150 on 16ohms for a long time and ran a 4 or 8ohm cab on it. It took a long while but eventually his head fried and had to have a whole circuit repaired and power tubes replaced.

 

[ochants76]

Krank does NOT recommend doing that...it does not deliver more power either. I have the exact words of one of kranks techs somewhere...I will post it when I find it again. Their cabs are wired in parallel so you have the option of running a cable from one cab to the next eliminating the need for a really long patch cable..that is the only reason.

It also will not deliver any more power than normal...if the head puts out 100 watts....that is what comes out...no matter how many or how few speakers are used and no matter if one or 2 outputs is used.

 

[Downtime]

if the head puts out 100 watts....that is what comes out...no matter how many or how few speakers are used and no matter if one or 2 outputs is used.

That´s it. And don´t forget that for example 200 watts are NOT the double power of 100, which is often forgotten in a context like this.

 

[ochants76]

That´s it. And don´t forget that for example 200 watts are NOT the double power of 100, which is often forgotten in a context like this.

well technically it IS double the power..but not double the volume

 

[C_F_H_13]

I would keep the head on 4 ohms and run it into the cab mono with one speaker cable.

And from what I am aware of, you should never connect an ohm load higher than what your amp is switched to.

Dont set the head to 16ohms and plug in a 4 ohm cab because it can damage the head.

You are better off either matching the cab or leaving the head on 4ohms.

My friend kept his 5150 on 16ohms for a long time and ran a 4 or 8ohm cab on it. It took a long while but eventually his head fried and had to have a whole circuit repaired and power tubes replaced.

So running the head at 16 ohms into the "mono" 16 ohm input is fine right? or 4 to 4, just not 16 to 4....hahaha confusing.

And the 8 ohm inputs on the cabinet are only in "stereo mode" right...as per this pic...

http://cachepe.zzounds.com/media/qu...s/stereo-d1b09cbfa88886b932120ad6c4f551e4.jpg

 

[ochants76]

yep you are exactly right

 

[Loren Littlejohn]

more cabs have always sounded louder to me, but it could be there is just more speaker pushing air.

It will not be stereo however that my friend is silly.

 

[C_F_H_13]

more cabs have always sounded louder to me, but it could be there is just more speaker pushing air.

It will not be stereo however that my friend is silly.

hahaha yeah. I didn't think it'd be actually "Stereo" I was just going by the labeling on the cabinet.

Alright, sticking with 16 ohms...thanks fellas!

 

[Downtime]

well technically it IS double the power..but not double the volume

Yep, that´s what I meant to say. It way late at night over here and since I´m not -that- english-language-crack...

 

[MetalWorks]

Krank does NOT recommend doing that...it does not deliver more power either. I have the exact words of one of kranks techs somewhere...I will post it when I find it again. Their cabs are wired in parallel so you have the option of running a cable from one cab to the next eliminating the need for a really long patch cable..that is the only reason.

It also will not deliver any more power than normal...if the head puts out 100 watts....that is what comes out...no matter how many or how few speakers are used and no matter if one or 2 outputs is used.

Then I guess we both have received conflicting information.

I said for the most power, not for more power.

A Krank Cab is 16ohms.

2 16ohm parallel speakers are 8ohms. Try hooking up an 8ohm cab next to a 16ohm cab or a 4ohm cab next to an 8ohm cab. The lower number will always be louder.

So in theory, 2 lower ohm loads with their own output would be louder than 1 higher ohm cab.

Its not much, but its noticeable.

In the case of the Marshall it probably doesnt matter because standarly its a 4ohm cab. In the case of a Krank cab its a 16ohm which is why I brought up Krank in the first place.

 

[MetalWorks]

hahaha yeah. I didn't think it'd be actually "Stereo" I was just going by the labeling on the cabinet.

Alright, sticking with 16 ohms...thanks fellas!

It will be quieter and thinner sounding at 16 ohms.

But I guess if you like the sound of it thats another thing. 4ohms is pretty meaty sounding, but I like that.

Running a Marshall 1960a/b 4x12 at 4 ohms mono is standard.

 

[ochants76]

Then I guess we both have received conflicting information.

I said for the most power, not for more power.

A Krank Cab is 16ohms.

2 16ohm parallel speakers are 8ohms. Try hooking up an 8ohm cab next to a 16ohm cab or a 4ohm cab next to an 8ohm cab. The lower number will always be louder.

So in theory, 2 lower ohm loads with their own output would be louder than 1 higher ohm cab.

Its not much, but its noticeable.

In the case of the Marshall it probably doesnt matter because standarly its a 4ohm cab. In the case of a Krank cab its a 16ohm which is why I brought up Krank in the first place.

I own both a krank cab and a marshall 1960 cab. What I was saying is that if you use two cables it makes NO difference. Krank does not condone this either. And technically ohm settings won't make it louder(as far as dbs) but your ears may be tricked into thinking so due to a difference in frequency.

16 ohm = hi-fi / articulate sound
4ohm = punchier, less defined sound
8ohm = middle of the road
(keep in mind that the differences are very very subtle)

Some will say lower is better some will say higher is better. One is not better than the other...if that was the case, all amps and cabs would be the same. If you have the option with your cab/amp combo you should see what you personally like best.

 

[MetalWorks]

I own both a krank cab and a marshall 1960 cab. What I was saying is that if you use two cables it makes NO difference. Krank does not condone this either. And technically ohm settings won't make it louder(as far as dbs) but your ears may be tricked into thinking so due to a difference in frequency.

16 ohm = hi-fi / articulate sound
4ohm = punchier, less defined sound
8ohm = middle of the road
(keep in mind that the differences are very very subtle)

Some will say lower is better some will say higher is better. One is not better than the other...if that was the case, all amps and cabs would be the same. If you have the option with your cab/amp combo you should see what you personally like best.

I personally have to turn my amp up another 25% when connecting an 8ohm cab instead of my 4 ohm. I understand what you are saying by perception, but a 25% loss in volume is more than perception to me.

Try connecting an 8ohm Mesa and a 16ohm Krank together and the Krank is definately quieter. Almost cant tell if its playing when to cabs are next to eachother.

Same with a 4ohm Marshall and a 8ohm Mesa.

Now if you simply flip the ohm switch on the head with the same cab, there is not much difference in volume. But 2 different cabs with the same head is clear.

If you search the net you will find everyone saying the same thing.

Example from someone who asked the same question about ohms and volume on yahoo:

So, in a nutshell, if your amp's output load impedance is rated for 8-ohms, and you put a 16-ohm speaker on it, you will essentially get half the normal volume of the amp, whereas putting a 4-ohm speaker on it, will result in twice the volume.

Its strange that you have a Krank Cab and a Marshall Cab and dont see the difference.

Plug the two in for a minute with the head on 4ohms and the Marshall in the 4ohm jack and connect the Krank cab and tell me its not hard to hear the Krank......

 

[ochants76]

What are you saying? I am not going to plug my head into two different ohm rating cabs at the same time.

I plugged into the marshall and set it at 4 ohms and measured with my decibel meter and then did the same with the krank on 16...the difference between the 2 fluctuates between .4 and .8 dbs. Which is pretty much the same.

Maybe if I cranked the head waaay up it might be different but I have no reason to do so.

Hmm..
If you are in fact correct wouldn't it make more sense to use a higher ohm load cab to get better power tube saturation?

 

[MetalWorks]

Possibly.

I have never tryed them quietly as I have always done the comparison in a band rehearsal/show volume.

Like you said, I would just go with what sounds best.

 

[ochants76]

yes definitely...when I checked them it was at rehearsal volume but then again I don't really play extremely loud.

oh well

 

[ochants76]

Here is the truth in the words of Lord Valve

(jim black) writes:
>
>I just got a 4x12 cab and I'm wondering why its 16ohms. Wouldn't it
>produce better if it was wired at 8ohms instead????Why 16??
>
>THANX
>BLACKIE

Lord Valve Speaketh:
First of all, a 16-ohm cabinet *cannot* be rewired to 8 ohms.
It can be wired for 4 ohms, or 64 ohms (not useful) but not 8.
If by "produce better" you mean it would allow the amp to deliver
more wattage, this is only true of solid-state amps...most of
which ship with 8- or 4-ohm cabinets anyway. For a tube amp,
as long as the output impedance selector is matched to the
impedance of the cabinet, the power will be the same at any
impedance. Running a tube amp at 16 ohms is advantageous on
two counts, however; first, it allows the amp's power to be
developed across the entire output transformer secondary winding
instead of just a portion of it, as would happen with an 8- or 4-
ohm load. Second, the higher impedance minimizes the effect of
speaker-wire resistance, thus improving power transfer.



so...I am sticking with my 16 ohms