Curious Combo Power Question

[la bam]

Evening all,

Just bought my Mark Bass rig (LM3 and Traveller 2x10) after years of wanting Mark bass. (300w@8ohm, 500w at 4ohm).

Ive just upgraded from a Line 6 Lowdown 300Pro (300w)

Now, i know all about sound being measured in spl and not watts etc - but the Mark bass, despite being rated at 300w @ 8ohms isnt just louder than the Line 6 - it is unbelievably louder. Truly unbelievably louder.


Which lead me to thinking, and i cant find the answer - in combos of any make, where its stated say a 300w combo, are we being a bit mislead, and the amp head gives off 300w at 4ohm, but the combo is actually a 8ohm and therefore 150w speaker?

So technically, theyre not lying, but to me a 300w combo should be giving 300w for whatever speaker is attached.

Ive had a look around and non of the models ive looked at actually state the head and speaker impedance.


Just curious, thats all.

[icastle]

I had a Line 6 amp head for a (very) short time and was totally underwhelmed by it.

I think many manufacturers use the 'if you add an 8Ω extension speaker' in small writing somewhere in the instruction manual whilst merrily giving the combo a name like 'ZXP300'...

[chris_b]

Is there a socket for an extension cab? If so your 300 watt amp will only be putting approx 150 watts into the internal speaker.

[Lozz196]

Plus you have to factor in the speaker sensitivity. The difference between, say 99 db sensitivity and 104 db will be significant.

[xgsjx]

Markbass use B&C drivers which have a longer excursion rate than most others. This means the driver has a bit more travel (3mm more) so is able to push more air.
Watts really mean very little compared to all the other stats that goes into showing how loud a combo is.

[charic]

Underwhelmed by the 300pro? Really? I had that amp for a couple of years and actually brought down a small part of a church with it (yes, really)

[StraightSix]

Most amps put out their maximum power into 4ohms.

Look at the speaker in the Behringer and you will probably see it is an 8ohm driver.

[icastle]

[quote name='charic' timestamp='1328178151' post='1522975']
Underwhelmed by the 300pro? Really? I had that amp for a couple of years and actually brought down a small part of a church with it (yes, really)
[/quote]

Nope.
I was underwhelmed by an HD750 head.
I've not tried their combos but that experience sort of soured things between my wallet and Line 6.

Having said that, both of the guitarists in my band use POD XT Lives and they work fine and sound great.

[la bam]

I dont think there is any info when looking at combos.

ie it doesnt say on a 300w combo that the speaker is say 4 or 8ohm and doesnt give info an the amp ratings at 4 and 8 ohm. It just classes them as a 300w combo.


I suppose what im getting at is that the 300w combos or 500w combos etc are not giving out 300w or 500w as part of that combo set up at all. As im beginning to believe that the watt rating is what the head gives off at 4ohm, but if it has a 8ohm speaker added as part of a combo - its misleading to give that power rating its never going to get chance to run at 4ohm.


Just having a midweek whinge!

[xgsjx]

[quote name='la bam' timestamp='1328204534' post='1523699']
I dont think there is any info when looking at combos.

ie it doesnt say on a 300w combo that the speaker is say 4 or 8ohm and doesnt give info an the amp ratings at 4 and 8 ohm. It just classes them as a 300w combo.


I suppose what im getting at is that the 300w combos or 500w combos etc are not giving out 300w or 500w as part of that combo set up at all. As im beginning to believe that the watt rating is what the head gives off at 4ohm, but if it has a 8ohm speaker added as part of a combo - its misleading to give that power rating its never going to get chance to run at 4ohm.


Just having a midweek whinge!
[/quote]
The manufacturer usually gives most of the specs on the website, but rarely the ones that mean anything.
How many watts it is means very little, though if you look in the back of your MB combo (lift the velcro lid up) it should give you some info & further reading in the manual for more.

Most combos that don't have an ext speaker connection are loaded with a 4 ohm driver (though not always).

[paulbass]

I have experienced this problem myself.Having used separate head and cabs for many years i decided to get a trace elliot 1210 combo rated at 500 watts.This gave a great sound BUT you needed to buy another cab to be able to get the full wattage.The combo only gave out half of the wattage on its own.
I was gutted as the idea of buying a combo was that i wouldnt have to carry loads of kit.
After 18 months i decided to go back to separates again.There are some great small,compact bits of kit out there and they do the business.

[xgsjx]

Your TE combo would be just like having the separate head & One 8Ω 2X10 cab. You would still have to add another 8Ω cab to draw the full wattage from the head. If you used a 4Ω 2x10 cab with your head to get the full amount watts out of it, you'd be hard pressed to notice any difference in volume, whereas 2 8Ω 2x10 cabs are gonna move a lot more air.

[chrisdaman]

I think youre right about the misleading power question

Ive been looking at the ashdown abm series combos, theyre advertised as 575w, but the technical info says impedance is 8ohms, so until you buy and extension cab, youre only getting 285w, which isnt bad, but annoying if youre thinking you can rock out with 575w straight away

A ploy to make more money for sure

[xgsjx]

Ignore how many watts it is gonna give you at 8Ω, it doesn't directly equate to how loud a thing is. My MB combo is marketed by shops at being 400w (no idea where they get that figure from, probably as it's 2 200w drivers). The head is 500w @ 4Ω & as it's basically attached to an 8Ω 2x10, is about 300-350w @ 8Ω.
TC electronics make an amp that is marketed at being 450w at 4Ω but actually only puts out 236w at 4Ω. But it's apparently as loud as an amp marketed at 450w.

[la bam]

It is misleading, if a speaker reaches its rated spl at say 300w, its misleading to quote that spl figure when the amp attached to it is only ever going to give it 150w.

(ie 300w at 4ohm and 150w at 8ohm - and theres an 8ohm speaker attached).


Surely if sold as a combo, the ratings should be a lot clearer, and should give the figures for that combination, not theoretical figures if you add cabs/change impedence etc.

ie
if the stats show:

300w
spl 100db at 1m

but really should show

150w
spl 95db at 1m

(not exact figures but you get the idea).


When we all buy separate heads and cabs, we all work out the proper wattage and therefore match for the optimum spl. I dont see why combos are different.

[xgsjx]

They're not. Think of it like a head & a single 8Ω cab. Also watts do not equate to the SPL. It doesn't quite work like that.

Your combo (the newer version of mine) is just the same as buying a LMIII & a 2x10 8Ω cab. It puts out the same SPL, the cab is rated at 400w & the xmax is the same & so on.
If it was a 4Ω cab, you're still gonna have a 400w cab that is still gonna give the same amount of SPL but you wouldn't be able to add another cab to it to increase that SPL.
So when looking at combos, go for the ones that are on an 8Ω load so you can add to it (as opposed to being stuck when you run out of oomph & canny add another cab).