Ohms... What the hell !!!

[Westie9]

My most sincere aplogies but I still don't have a clue about all this 'ohms' thing. Can someone explain it in a complete moronic way please, so that my tiny little brain can attempt to compute with !!!

My main question is: I run a Genz Benz Streamliner 600 (375 @ 8ohms and 600 @ 4), into 2 EBS Neo 112's (8 ohms each).
Now, don't laugh, if I use 1 output from the Streamliner into 1 cab, and then daisychain this cab into the second cab, does this mean that each cab runs at 4 ohms, thus giving me the best output for the Streamliner? Is it the same when using the 2nd speaker output from the Streamliner, so, 1 to each cab?

Now, if I added a 15" cab (again 8ohm) from 1 channel on the Streamliner, daisychained this into a single 12" cab, allowing me then to use the second 12" cab as a personal monitor for me on stage using the second output from the Streamliner, what would that give me or would the amp just turn into a molten piece of plastic and metal!!!

The main problem I have is that I don't go through the PA and I have difficulty hearing myself on stage so I do need the extra cab as a monitor.

Any ideas for a thicko ???

Edited September 2, 2011 by Westie9

[51m0n]

Typically (as in , the industry standard complied with by all cabs and amps I've ever seen or used) any multiple socket array of outputs/inputs to/from speakers are wired in parallel not series.

This is very important.

So it makes no diff to the circuit wether you use the two outs on the back of the amp, one to each cab, or the two outs on one of the cabs to daisy chain. The resulting circuit you've built is the same, two speakers wired in parallel to the amp.

In order to work out the total impedance in a parallel circuit the formula is as follows:-

1/total = 1/speakerA + 1/speakerB + 1/SpeakerC..... through all the speakers stated impedances.

In the case of 2 8 ohm cabs in parallele weget:-

1/Total = 1/8 + 1/8 = 2/8 = 1/4

so Total= 4 Ohms.

That 4 ohms is the total load across the amp, if it is rated to 4 ohms it is a happy amp at this point.

Things get complex when you have differently rated impedances on the speakers though, since the lower impedance speaker will get more current than the higher impedance speaker.

Simplest rule of thumb is to stick with the same impedance cabs for now!

[derrenleepoole]

In very simple layman's terms, you're halving the value each time. So two 8 ohm cabs together, whether they're run out of each individual output of your amp, or run in a chain will result in a total 4 ohm impedence. Adding another cab would NOT be recommended as this would run you below your minimum safe load

It took me a while to grasp ohmage terms, but once it sinks in it's very easy to understand.

Edited September 2, 2011 by derrenleepoole

[Tait]

[quote name='51m0n' post='1359654' date='Sep 2 2011, 11:20 AM']Typically (as in , the industry standard complied with by all cabs and amps I've ever seen or used) any multiple socket array of outputs/inputs to/from speakers are wired in parallel not series.

This is very important.

So it makes no diff to the circuit wether you use the two outs on the back of the amp, one to each cab, or the two outs on one of the cabs to daisy chain. The resulting circuit you've built is the same, two speakers wired in parallel to the amp.

In order to work out the total impedance in a parallel circuit the formula is as follows:-

1/total = 1/speakerA + 1/speakerB + 1/SpeakerC..... through all the speakers stated impedances.

In the case of 2 8 ohm cabs in parallele weget:-

1/Total = 1/8 + 1/8 = 2/8 = 1/4

so Total= 4 Ohms.

That 4 ohms is the total load across the amp, if it is rated to 4 ohms it is a happy amp at this point.

Things get complex when you have differently rated impedances on the speakers though, since the lower impedance speaker will get more current than the higher impedance speaker.

Simplest rule of thumb is to stick with the same impedance cabs for now![/quote]

What he said!

And FWIW if they [i]were[/i] in series just add them all up. But like 51m0n says, they'll almost definitely be in parallel.

Edited September 2, 2011 by Tait

[chris_b]

For a 4 ohm maximum load which is what 99% of amps do, you can plug in 1 8 ohm cab, 2 8 ohm cabs or 1 4 ohm cab.

Don't plug in 3 or more cabs or mix 8 ohm and 4 ohm cabs.

[EdwardHimself]

[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']Any ideas for a thicko ???[/quote]

Yes. You've already got 2 8 ohm speakers on a 4 ohm min load amp. Don't add any more speakers otherwise you'll bugger it up, in Layman's terms.

Edited September 2, 2011 by EdwardHimself

[derrenleepoole]

[quote name='Tait' post='1359673' date='Sep 2 2011, 11:33 AM']What he said!

And FWIW if they [i]were[/i] in series just add them all up. But like 51m0n says, they'll almost definitely be in parallel.



Halving works only if it's entirely 8 ohms or entirely 4 ohms. The OP had a mixture of both, so would do better to follow the formula 1/R=1/r1+1/r2+1/r3... or as 51m0n said,
1/total = 1/speakerA + 1/speakerB + 1/SpeakerC..... through all the speakers stated impedances.[/quote]

Yes, but the guy wanted simple, layman's terms. You're clearly way more capable than me at grasping the full mathematics of what is required, but not everyone needs that. Start simple for now, get more complicated as your experience improves. Laying on a full barrage of mathematics is likely to be more confusing than helpful - even though it is helpful

[EdwardHimself]

[quote name='derrenleepoole' post='1359687' date='Sep 2 2011, 11:40 AM']Yes, but the guy wanted simple, layman's terms. You're clearly way more capable than me at grasping the full mathematics of what is required, but not everyone needs that. Start simple for now, get more complicated as your experience improves. Laying on a full barrage of mathematics is likely to be more confusing than helpful - even though it is helpful [/quote]

To be honest, saying that you're halving the impedance each time which is only true if both speaker impedances match up, imo is more confusing than helpful. You shouldn't give advice about something if you don't know how it works.

Edited September 2, 2011 by EdwardHimself

[derrenleepoole]

[quote name='EdwardHimself' post='1359695' date='Sep 2 2011, 11:44 AM']To be honest, saying that you're halving the impedance each time which is only true if both speaker impedances match up, imo is more confusing than helpful. You shouldn't give advice about something if you don't know how it works.[/quote]

I do know how it works!

My advice was no different to yours. Quote: Yes. You've already got 2 8 ohm speakers on a 4 ohm min load amp. Don't add any more speakers otherwise you'll bugger it up, in Layman's terms!

I give up! Later grumpy people :/

Edited September 2, 2011 by derrenleepoole

[flyfisher]

[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']My most sincere aplogies but I still don't have a clue about all this 'ohms' thing. Can someone explain it in a complete moronic way please, so that my tiny little brain can attempt to compute with !!!

My main question is: I run a Genz Benz Streamliner 600 (375 @ 8ohms and 600 @ 4), into 2 EBS Neo 112's (8 ohms each).
Now, don't laugh, if I use 1 output from the Streamliner into 1 cab, and then daisychain this cab into the second cab, does this mean that each cab runs at 4 ohms, thus giving me the best output for the Streamliner?[/quote]
Yes. (although it doesn't change the ohms of each cab, but two 8 ohm cabs connected in parallel with 'look like' 4 ohms to the amp)


[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']Is it the same when using the 2nd speaker output from the Streamliner, so, 1 to each cab?[/quote]
Yes.


[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']Now, if I added a 15" cab (again 8ohm) from 1 channel on the Streamliner, daisychained this into a single 12" cab, allowing me then to use the second 12" cab as a personal monitor for me on stage using the second output from the Streamliner, what would that give me or would the amp just turn into a molten piece of plastic and metal!!![/quote]
Yes - molten plastic! (probably).

What you would be doing is connecting a 4 ohm load (i.e. the two 8 ohms cabs in parallel) to one amp output and an 8 ohm load (i.e. the stage monitor cab) to the other amp output.

The result is that the amp will 'see' a combined load of 2.7 ohms, which is below the design minimum of 4 ohms. This is a bad thing.



[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']The main problem I have is that I don't go through the PA and I have difficulty hearing myself on stage so I do need the extra cab as a monitor.

Any ideas for a thicko ???[/quote]

If you really have to work with the gear you already have then one possibility would be to wire up the two main cabs in [u]series[/u] instead of parallel (this would need some special cables). This would give a combined load of 16 ohms. Add this (in parallel) to the 8 ohm stage monitor and the amp would 'see' a load of 5.3 ohms, which is perfectly safe. BUT, the power would not be equally distributed between all cabs. 2/3rds of it would go to your stage monitor and only 1/3rd to the two main cabs, split equally between them. So, not a very good solution.

Or, you could just use two cabs, one as a stage monitor.

Or, best of all, stick to your two main cabs and get the sound guy to give you a stage monitor (perhaps your spare cab) driven from the mixing desk.

[EdwardHimself]

[quote]I do know how it works!

My advice was no different to yours. Quote: Yes. You've already got 2 8 ohm speakers on a 4 ohm min load amp. Don't add any more speakers otherwise you'll bugger it up, in Layman's terms!

I give up! Later grumpy people :/[/quote]

The difference is that my advice wasn't misleading. I decided there was no point in quoting the old 1/r[sub]t[/sub]=1/r[sub]1[/sub]+1/r[sub]2[/sub]+... formula because someone else already had and the OP probably didn't need to know that. What I didn't do was make up some rule that only works in a small amount of cases that could lead to confusion in the future. If you do know how it works then you fooled me with what you said into thinking you didn't.

Edited September 2, 2011 by EdwardHimself

[derrenleepoole]

[quote name='EdwardHimself' post='1359709' date='Sep 2 2011, 11:55 AM']The difference is that my advice wasn't misleading. If you do know how it works then you fooled me with what you said into thinking you didn't.[/quote]

If any individual is really struggling to understand how ohm's work for amp loads, then giving them a load of mathematical interpretations of the problem/solution is indeed very helpful. But that approach assumes that they (the OP in this case) understands such terminology, which is a big assumption to make. Given that the OP asked for layman terms, it's unlikely that this approach will be totally helpful, although it could well be. We have to make the assumption though that the simpler approach is probably better.

For the sake of argument... yes, an 8 ohm load into a 4 ohm load is not exactly half. But, for the sake of demonstrating simply that it's a bad idea, and for .7 of an ohm difference, my explanation, while not perfect, is in essence what is going on. Not totally accurate, and not totally incorrect either. The OP should now know that it's a bad idea to mix and match their cabs, even if they don't fully get why. Given enough time, they will. Start simple, get more complicated.

I admit it wasn't totally right... but seriously, is it worth an ear bashing for, when the guy only wanted simple?

Right, can we all just get along please? Peace.

Edited September 2, 2011 by derrenleepoole

[icastle]

If you want a quick answer without the mathematics then use [url="http://ampservice.de/impcalc.php?lang=e"]this[/url].

[derrenleepoole]

[quote name='icastle' post='1359767' date='Sep 2 2011, 12:43 PM']If you want a quick answer without the mathematics then use [url="http://ampservice.de/impcalc.php?lang=e"]this[/url]. [/quote]

Great tool. Saved. Thanks

[Happy Jack]

[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']Now, if I added a ... personal monitor for me on stage ... would the amp just turn into a molten piece of plastic and metal!!![/quote]

No, because you'd use a powered wedge and feed it with the Tuner Out on the Genz Benz.

These things ( [url="http://www.dv247.com/pa-systems-and-live-sound/studiomaster-pax10plus--powered-10-active-wedge-monitor--75424"]http://www.dv247.com/pa-systems-and-live-s...-monitor--75424[/url] ) are excellent.

And nary an Ohm to be seen.

[stingrayPete1977]

[quote name='Happy Jack' post='1359789' date='Sep 2 2011, 01:02 PM']No, because you'd use a powered wedge and feed it with the Tuner Out on the Genz Benz.

These things ( [url="http://www.dv247.com/pa-systems-and-live-sound/studiomaster-pax10plus--powered-10-active-wedge-monitor--75424"]http://www.dv247.com/pa-systems-and-live-s...-monitor--75424[/url] ) are excellent.

And nary an Ohm to be seen. [/quote]
But then where would my tuner go?

[Happy Jack]

Clipped to the headstock of course ...

[icastle]

[quote name='stingrayPete1977' post='1360204' date='Sep 2 2011, 06:08 PM']But then where would my tuner go? [/quote]

After editing out all the suggestions requiring axle grease and\or a degree of double jointedness...

[stingrayPete1977]

[quote name='Happy Jack' post='1360211' date='Sep 2 2011, 06:17 PM']Clipped to the headstock of course ...[/quote]
Never on stage, just dont do it!

[Bloodaxe]

[quote name='Westie9' post='1359639' date='Sep 2 2011, 11:13 AM']My most sincere aplogies but I still don't have a clue about all this 'ohms' thing. Can someone explain it in a complete moronic way please, so that my tiny little brain can attempt to compute with !!![/quote]
It goes like this...
[list]
[*]All electronics work because they're filled with Magic Smoke,
[*]The smoke is pushed around the system by means of Physics (or "Witchcraft" if you prefer something more understandable) via a system of Special Pipes usually called "Wires" or "Cables".
[*]The Ohms act like a sort of kitchen tap, or a hosepipe nozzle - If you get the Ohms right, a nicely balanced amount of Magic Smoke travels around the pipes.
[*]If you have too many Ohms they restrict the flow of Smoke & everything gets a bit weedy and useless (think of standing on the hosepipe).
[*]If, however, you don't have [i]enough[/i] Ohms [b]too much[/b] Magic Smoke comes down the pipe, causing it to burst & it all leaks out.
[/list]This last point leads to a situation that electronic engineers commonly refer to as "ItzFuktMate", so it is best avoided as they will demand a large sacrifice of Money to put a patch on the burst pipe & refill the system with Magic Smoke.

[size=1](You can stop thinking about standing on the hosepipe now, but only if you want to.)[/size]

[icastle]

[quote name='Bloodaxe' post='1360640' date='Sep 3 2011, 02:31 AM']It goes like this...
[list]
[*]All electronics work because they're filled with Magic Smoke,
[*]The smoke is pushed around the system by means of Physics (or "Witchcraft" if you prefer something more understandable) via a system of Special Pipes usually called "Wires" or "Cables".
[*]The Ohms act like a sort of kitchen tap, or a hosepipe nozzle - If you get the Ohms right, a nicely balanced amount of Magic Smoke travels around the pipes.
[*]If you have too many Ohms they restrict the flow of Smoke & everything gets a bit weedy and useless (think of standing on the hosepipe).
[*]If, however, you don't have [i]enough[/i] Ohms [b]too much[/b] Magic Smoke comes down the pipe, causing it to burst & it all leaks out.
[/list]This last point leads to a situation that electronic engineers commonly refer to as "ItzFuktMate", so it is best avoided as they will demand a large sacrifice of Money to put a patch on the burst pipe & refill the system with Magic Smoke.

[size=1](You can stop thinking about standing on the hosepipe now, but only if you want to.)[/size][/quote]

Oh very well done - I absolutely love it!

[Jack]

Whilst we're being educational, the word is 'impedance', not 'ohmage' or anything else of the like. You don't say 'kilometreage', you say 'distance'. One is the measurement and one is the unit.


(I guess for some reason we do say 'footage' when measuring distance or area but I digress.)

[Mr. Foxen]

[quote name='Jack' post='1361329' date='Sep 3 2011, 09:17 PM']Whilst we're being educational, the word is 'impedance', not 'ohmage' or anything else of the like. You don't say 'kilometreage', you say 'distance'. One is the measurement and one is the unit.


(I guess for some reason we do say 'footage' when measuring distance or area but I digress.)[/quote]

Mileage. The impedance thing is more importantto differentiate it from resistance. And cabs is nominal impedance anyway, so isn't really impedance, 'ohmage' is probably better thought of as a term meaning 'nominal impedance as applied to speakers'.

[Jack]

Well, I'd argue that mileage is specifically the distance a car has been, you don;t really say the mileage between two points is such and such. Hmmmmm, maybe I guess. Anyways, now we're splitting hairs and I started it, so I'm sorry.


I know it's a nominal impedance across the range of frequencies, but we still talk about a 4 ohm cab as having an impedance of 4 ohms. The impedance of the load when two cabs connected is therefore 2 ohms. I suppose to me or you they could be interchangeable but there seem to be (and I don't mean to offend) a few people in here with less of a technical understanding, and I'd hate for them to pick up bad habits or not understand what a word means. There's nothing to connect the word impedance to anything in this discussion if you saw it written on the internet.

Personally I've always used magic smoke too.

[Westie9]

Many thanks fellow Basschatters for the help. Really appreciated...