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Ohmage once more... Single cab solutions


uk_lefty
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So here's the quandary. I have an Ashdown Rootmaster 500 head which is pretty hard to beat, currently played through a single 1x15 Rootmaster cab that rates at 500watts at 8 ohms. I have used two cabs with this before but currently only have the one. I'm also considering taking the head unit put of a Trace combo for gigs where I want the sound of a trace amp but without the weight of the full 2x10 combo.

 

Is it worth me getting a 4 ohm cab? Looking at the 4x10 Ashdown lightweight cab at the moment. Will it give me more output than the 1x15 on its own? I played a function with the RM head and 1x15 cab only and I couldn't hear myself on stage though I think that's because I didn't elevate the cab. I know volume isn't the pure aim of the game but I'm looking to get the most out of my amps in the smallest set up I can... Without spending crazy money or going for something like the Elf set up, I find anything smaller than a 2x10 a bit weird tbh (irrational I know).

 

Any advice gratefully received.

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1. (Pedant alert) it’s impedance, not ohmage ;)

2. A 4x10 will be louder than a 1x15 most likely. The impedance doesn’t really make much difference.

Bill Fitzmaurice made a good point in another thread recently about “getting the maximum from an amp” - I’ll see if I can find it.

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23 minutes ago, Merton said:

Here it is:

 

I'm not sure I fully understand it, but I think the point is that if I were to go from my 8ohm cab to an equivalent 4ohm cab there'd be bog all difference? Combined with your point that a 4x10 is likely to be a bit louder... Overall it just seems like I don't need to take the financial hit of selling off the fifteen to buy something else, I won't get my money's worth.

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2 hours ago, uk_lefty said:

 I played a function with the RM head and 1x15 cab only and I couldn't hear myself on stage though I think that's because I didn't elevate the cab.

Elevate the cab, or at the very least tilt it back so you're on the driver axis. Adding a 410 to a 115 seldom works well, as most 115s can't keep up with a 410. 90% of the time you'll get the best results with two identical cabs.

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Just now, Bill Fitzmaurice said:

Elevate the cab, or at the very least tilt it back so you're on the driver axis. Adding a 410 to a 115 seldom works well, as most 115s can't keep up with a 410. 90% of the time you'll get the best results with two identical cabs.

Thanks, I was considering replacing the 8ohm 1x15 with a 4ohm 4x10 but I think I'll try one of those amp stands that puts it on an angle first. And saving myself best part of £350

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A 410 v 115 from the same range should def be louder. Having had the 4ohm 410 and the 8ohm 210 from the RM range the 410 was def louder. I put this down to double the number of speakers as much as the impedance, as there was just a much bigger sound  with it. 

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3 minutes ago, Lozz196 said:

A 410 v 115 from the same range should def be louder. Having had the 4ohm 410 and the 8ohm 210 from the RM range the 410 was def louder. I put this down to double the number of speakers as much as the impedance, as there was just a much bigger sound  with it. 

Yes. More speaker area means more volume. Impedance isn’t really relevant in volume discussions when comparing 8 or 4 ohms :)

(For instance, my glorious One10 pair is loud enough for all but one of my bands. So for that, I’m going to add more speakers, but the impedance will go up because of the way I’ll wire it. It’ll still be more louderererer)

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6 hours ago, uk_lefty said:

I'm not sure I fully understand it, but I think the point is that if I were to go from my 8ohm cab to an equivalent 4ohm cab there'd be bog all difference? Combined with your point that a 4x10 is likely to be a bit louder... Overall it just seems like I don't need to take the financial hit of selling off the fifteen to buy something else, I won't get my money's worth.

A typical 410 will be a lot louder whether it is 4 ohm or 8 ohm.

 

You still won't hear it down on the floor on a small stage.

 

Try elevating the 15 before doing anything.

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14 hours ago, Merton said:

Yes. More speaker area means more volume. Impedance isn’t really relevant in volume discussions when comparing 8 or 4 ohms :)

(For instance, my glorious One10 pair is loud enough for all but one of my bands. So for that, I’m going to add more speakers, but the impedance will go up because of the way I’ll wire it. It’ll still be more louderererer)

This is interesting then. Ashdown do their Rootmaster 4x10 cabs in either 4 ohm or 8 ohm. So, using my RM head that runs at either 4 or 8 ohms assumedly if I buy the 4 ohm version I've got the option to add another cab should I want to. If I add the 8 ohm version I can't, or shouldn't anyway. From what I read here both 4x10s would give me the same output off the same head.... So why do separate versions exist? What is the advantage of the 8 ohm version? I've noticed there are not a lot of 8 ohm cabs on the market from the reasonably priced manufacturers (Ampeg, Ashdown, Markbass...) so I'm just wondering what the point of them is of there's no difference, only a restriction?

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3 minutes ago, uk_lefty said:

This is interesting then. Ashdown do their Rootmaster 4x10 cabs in either 4 ohm or 8 ohm. So, using my RM head that runs at either 4 or 8 ohms assumedly if I buy the 4 ohm version I've got the option to add another cab should I want to. If I add the 8 ohm version I can't, or shouldn't anyway. From what I read here both 4x10s would give me the same output off the same head.... So why do separate versions exist? What is the advantage of the 8 ohm version? I've noticed there are not a lot of 8 ohm cabs on the market from the reasonably priced manufacturers (Ampeg, Ashdown, Markbass...) so I'm just wondering what the point of them is of there's no difference, only a restriction?

Wrong way round. Your RM head can do 4 ohms minimum load, which means you could run two 8 ohm cabs or one 4 ohm.

They do this again because of this common myth that “getting full power from my head” means more volume. Which goes back to Bill’s post I shared earlier :)

Two 8 ohm 4x10s will be louder than one 4 ohm because you’re moving double the amount of air, not because you’re running the amp at its nominal minimum impedance.

Edited by Merton
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31 minutes ago, uk_lefty said:

This is interesting then. Ashdown do their Rootmaster 4x10 cabs in either 4 ohm or 8 ohm. So, using my RM head that runs at either 4 or 8 ohms assumedly if I buy the 4 ohm version I've got the option to add another cab should I want to. If I add the 8 ohm version I can't, or shouldn't anyway. From what I read here both 4x10s would give me the same output off the same head.... So why do separate versions exist? What is the advantage of the 8 ohm version? I've noticed there are not a lot of 8 ohm cabs on the market from the reasonably priced manufacturers (Ampeg, Ashdown, Markbass...) so I'm just wondering what the point of them is of there's no difference, only a restriction?

The 4 ohm one can be useful for some users of 50, 100, 200w solid state amps to save hauling another cab. Not what I would ever do though, lousy FOH dispersion from 410 cabs!!

Edited by Downunderwonder
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1 hour ago, uk_lefty said:

This is interesting then. Ashdown do their Rootmaster 4x10 cabs in either 4 ohm or 8 ohm. So, using my RM head that runs at either 4 or 8 ohms assumedly if I buy the 4 ohm version I've got the option to add another cab should I want to. If I add the 8 ohm version I can't, or shouldn't anyway. From what I read here both 4x10s would give me the same output off the same head.... So why do separate versions exist? What is the advantage of the 8 ohm version? I've noticed there are not a lot of 8 ohm cabs on the market from the reasonably priced manufacturers (Ampeg, Ashdown, Markbass...) so I'm just wondering what the point of them is of there's no difference, only a restriction?

The reason they sell 4 and 8 ohm versions of the cabs is that there is a demand from musicians for more watts. Part of that is from people who like to be able to talk about how big their stack is, part is that there is a smidgin of science about it and part is because of people being utterly confused by the advertising departments into desiring lots of watts.

 

The thing is that what you really want is sound levels, for want of a better unit lets say decibels. More watts through the same speaker will give you more decibels so long as you stay within the speakers operating limits. 100 wats through your Ashdown is going to give you louder bass than 50W. Just not as much as common sense might suggest. In fact with the same speaker operating within it's limits you'll get an extra 3db. Confusingly if you were operating at 1W you'd only need another 1W to get 3db extra volume. You've doubled the power and that gives you 3db. 

 

So now we go to your amp, theoretically it should give double the power into 4 ohms. and at low levels it will. Running at 1W you'll get the extra 3db into 4 ohms but at 300W into your poor amp will run out of puff (read current) and you will get 500W into 4ohms according to Ashdown. That's a lot of extra watts but not quite double the power so around an extra 2W. Confusingly though to make the speaker 4ohms you have to change the coil and that throws other things out. theory is simple the real world a bit messier. 

 

So how much louder is 3db. Well, it might be twice the power but it is nowhere near twice the volume. 1db is the smallest change you can hear, one click on the stereo, a just noticeable change, but if you left the room and you came back and someone had turned the telly down 1db you wouldn't notice. 3db is just about what you would notice. If your mix is right and you turn up 3db the bass would dominate, it wouldn't be silly but it would definitely be noticeable. Equally if the bass was just not quite there 3db would fix it, probably. These aren't iron rules, the sound engineer will be able to hear 1db changes and a ham fisted guitarist quite capable of adding an extra 6db wiping the balance out for everyone else.

 

You haven't said if you like your tone? If so then there is a very simple fix, buy a second 8ohm 15. Doubling the cone area will give you 3db extra and the extra 200W going to 4 ohms will give you another couple of db. 5db will make a difference even the guitarist will hear! 

 

 

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