Idiot question re ohms and so on

[uk_lefty]

Sorry to ask... But I want to check. At the moment I use two 8ohm cabs from my Ashdown RM 500 EVO head. These cabs are ashdown RM 1x15s but one is a 250w standard cab and the other is a 500w EVO version. Using them both together provides a serious amount of output that is ample for gigging.
Here comes the silly question: if I only use the Evo cab on its own am I getting the full 500w through it? Do I really need the 250w cab at all?

Second question, I quite fancy the Ashdown RM Evo 4x10 which is 600w in to 4 ohms. Same question, if I use this cab on its own, firstly is that ok ohms wise? And secondly will it be getting the full power from my amp head and no second cab required?

Hope that makes sense and apologies if it's a Noddy question but I've never understood the whole ohms thing. Thanks for any advice

[Merton]

If you use one 1x15 cab it's a single 8 ohm load so the amp will output around 300W. Using both gives you a 4 ohm load and the full power output.

If you get a 4 ohm 4x10 will give you full power into the one cab, but it will be the only cab you can use as adding other cabs will lower the impedance and the RM head won't like that.

Edited September 20, 2017 by Merton

[uk_lefty]

[quote name='Merton' timestamp='1505937638' post='3375399']
If you use one 1x15 cab it's a single 8 ohm load so the amp will output around 300W. Using both gives you a 4 ohm load and the full power output.

If you get a 4 ohm 4x10 will give you full power into the one cab, but it will be the only cab you can use as adding other cabs will lower the impedance and the RM head won't like that.
[/quote]

Superb! Thank you. I'm looking to downsize and I always fancied having tens but the 4 x 10 must be a new-ish product because I would have held out for it. I don't have enough room in the house (I've been told!) for the two fifteens and awesome as they sound together it would be better to just be taking a single cab around.

[skidder652003]

2 x 12 is all the rage around tgese here parts!

[uk_lefty]

[quote name='skidder652003' timestamp='1505938323' post='3375404']
2 x 12 is all the rage around tgese here parts!
[/quote]

If there was an affordable lightweight one of consider it, but I'm quite keen on the 4x10

[casapete]

Go for the 4x10, you'll love it.

[xgsjx]

I'd go for 2 15s over a 4x10. I'd prefer a 2x12 or 2 2x10s. I've got a 4x10.

[Lozz196]

Go for the 410, in fact, buy mine!

It`s up on here at £300 and I`ve upgraded the speaker cones to Eminence Betas (Ashdown themselves did the work) so it`s now rated at 1000 watts. Comes with Roqsolid cover and go-faster castors.

[url="http://basschat.co.uk/topic/311987-ashdown-rm-414t-evo-4ohm-410/"]http://basschat.co.uk/topic/311987-ashdown-rm-414t-evo-4ohm-410/[/url]

[Conan]

[quote name='Merton' timestamp='1505937638' post='3375399']
If you use one 1x15 cab it's a single 8 ohm load so the amp will output around 300W. Using both gives you a 4 ohm load and the full power output.
[/quote]

But the amp will only produce its "full power" (300W @ 8 ohms, or 500W @ 4 ohms) if it is run flat-out with all controls maxed. How many of us ever do this?

[Bill Fitzmaurice]

[quote name='Conan' timestamp='1506005186' post='3375831']
But the amp will only produce its "full power" (300W @ 8 ohms, or 500W @ 4 ohms) if it is run flat-out with all controls maxed. How many of us ever do this?
[/quote]That, plus the cab power rating doesn't necessarily reflect how much power it can actually make use of before the drivers run out of excursion. More often than not that's at less than half the rated power. Also, to sound twice as loud requires ten times the power. The flip side of that is at 1/10 the power it doesn't sound 1/10 as loud, it sounds half as loud. In short, the quest you so often see of "I want to get all of the watts out of my amp" is usually at best misguided, at worst delusional.

[uk_lefty]

[quote name='Bill Fitzmaurice' timestamp='1506006033' post='3375844']
In short, the quest you so often see of "I want to get all of the watts out of my amp" is usually at best misguided, at worst delusional.
[/quote]

Or maybe it's just poorly phrased due to a lack of in depth technical knowledge.

[Merton]

@Conan and Bill - yes I know but I was keeping it simple

[Conan]

[quote name='Merton' timestamp='1506014091' post='3375926']
@Conan and Bill - yes I know but I was keeping it simple
[/quote]

I know you know But the OP might not, so I thought it might be useful info

[Merton]

[quote name='Conan' timestamp='1506083123' post='3376331']


I know you know But the OP might not, so I thought it might be useful info
[/quote]

Ah! I didn't really consider that perhaps I should know that you knew that I know, d'oh!

Edited September 22, 2017 by Merton