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Dumb Question? Im confused!!

E

eupharies

Jul 3, 2007
555
2
Leeds UK
Disclosures
Bassist - Chasing Dragons
#1
Ok so im swapping my combo for a head / cab.

My combo is the ashdown abm EVO III 2x10...

Ok so the head is rated at 575watts... duno if that is for 4 or 8 ohms...

So i had a look at the cab i believe is in the combo which i will assume is the ABM 210T

Which is an 8 ohm cab 300watts continuous / 600watts programme..

So im confused.... im not quite sure what im confused about, its just i was thinking of getting the ABM 210T cab for the head i buy but... im confused!

well firstly what is the 600watts programme? what does this mean

and

Well if the cab is 300watts continuous and the amp head is 575watts... does this mean my Head ( within the combo) is limited to 300 watts.. as it would blow the cab otherwise...

Im very confused :( and dont get this technical stuff :(
 
#2
Don't be confused:)

For solid state amps like your Ashdown, the only spec that is even moderately important is the 8ohm and 4ohm output RMS wattage.

For your head, I believe the 4ohm output is 575 watts if I remember correctly. That means that the head will put out its full, safe power into one 4ohm cab or two 8ohm cabs (which combined have a nominal impedance of 4ohms). The 8ohm wattage is typically about 65% of 4ohm volume, so lets say about 350 watts.

The 'program' rating, peak rating, etc. should be ignorend... mostly marketing stuff.

When matching to a cab, the cabs 'power rating' is relatively unimportant, and can pretty much be ignored. You can't have 'too little power' going into any cab, and the power rating of a cab is really just a loose guide to the level of input power that MIGHT do a voice coil harm if that power was applied on a more 'programmed' basis (like a very compressed CD cranked through a system, where there are no 'recovery times' between the peaks).

So, the key is to not go below the minimum nomimal impedance of a head (with most heads, that is 4ohms). If you are buying a relatively large cab, and know you will only use one cab, a 4ohm version (if available) usually makes sense, since you will get a bit more power. Of course, if your head already puts out big power at 8ohms, you might not notice much of a difference. On the other hand, if you know you might want a second cab, or are using a small 8ohm cab, there would be no advantage to getting a 4ohm cab to start with.

If your head as a higher power output rating than the 'power safety spec' or your cab, you just need to use common sense. If you hear farting or 'power compression' (which sounds like a compressor turned up too much... your low end will disappear as you really dig in when playing loudly), then turn down a bit. If this happens all the time, then it is time for either a second cab or a larger single cab.

K
 
#4
^^^^ all that.

but let your ears decide. also search around some of the older (and newer- there's a new one weekly) threads that discuss different driver sizes and the pairing or not pairing of said different sized drivers. this can give you a better overall grasp of whether or not you go for a single or multiple cabs. but like anyone can tell you, only your likes and dislikes can truly help you decide what you want from your gear.
 
#5
eupharies said:
thanks for your reply!!

Ok i see sooooooooo

in effect, my combo is limited to the 8 Ohms / 300 watts it can handle... so in effect im wasting 275 watts?? im probably talking rubbish haha
Click to expand...

Think about it this way. Your amp is 'limited' to the lower 8ohm output with the single, internal combo cab. This is actually a good thing, since a small cab can't really use much more power than that (at least a standard production small cab with typical high sensitivity midrange drivers). So, the great thing about the way that most combo's are designed (including yours) is that the 8ohm output of the head is nicely matched to a single small cab like a 112 or 210, but then you have the option of adding a second 8ohm extension cab, which will both result in more power (going from 8ohms to 4ohms) and more cone area, resulting in, on average a 5db increase in volume (roughly 2db for the 40% or so increase in power, and 3db for doubling the cone area assuming adding an second identical cab). That is huge, and the low end will open up also, due to the coupling of the two cabs.

So, this is one of the advantages of a modular rig (whether it be two cabs and and a head, or a combo and extension cab). You can use the combo alone or a single cab for small gigs, and then add the second for larger gigs, and the solid state head will 'automatically' adjust its power output up and down depending on the impedance (i.e., number of cabs.
 
#6
on a second note, OP, does the amp in the combo have a connector for an external cab? if so, then you aren't exactly "wasting" that power, its just that the combo as is plays thru an 8 ohm load, and matches the included drivers' ratings. you then get to use up to the amp's max when you add a second 8 ohm cab. you aren't really "wasting" power using the combo as it sits.
 
#7
right right, i think i kinda get it so, 2 8 ohm cabs = the 40hm power on the am head..

So im correct in saying at the moment with my combo i can only get like 350watts, thats cool.

Well im swapping out my ABM evo III for a GK 700RB II, and was thinking of getting the ashdown cab...
 
#8
eupharies said:
right right, i think i kinda get it so, 2 8 ohm cabs = the 40hm power on the am head..

So im correct in saying at the moment with my combo i can only get like 350watts, thats cool.

Well im swapping out my ABM evo III for a GK 700RB II, and was thinking of getting the ashdown cab...
Click to expand...

+1 Two 8ohm cabs connected in parallel (i.e., either running out of two power outputs on a solid state head, or daisy chained together from one cab to the next) will result in a total nominal impedance of 4ohms, which will result in most solid state amps putting out their full, rated power.

The GK heads are very nice. I saw your other thread. They will be brighter and more aggressive in the upper mids (more grind) than the smoother, fatter tone of the Ashdown head you have now, which should work well.

The 700 is great. Don't eliminate the GK MB500... very small, very powerful, and that 'bright, grindy aggressive thing you describe that you want.

Both heads would be great pushing either a 4ohm 410 or two 8ohm 112's or 210's IMO.
 
#9
check out the threads and posts about mixing driver sizes in your rig. it answered a question about a rig i used to play that i didn't know how to ask. sure could have used TB in the 80's.
 
#10
Awesome, thanks for explaining, im easily confused with this stuff haha!

Yeh i must admit i am torn between the Gk mb500 / mb fusion and the 700RB II...

Id of course love the lightes one.. but most reviews say the mb500 is lacking vs the 700rb II... so i guess its a toss up between the mb fusion and the 700 rb II
 
#12
eupharies said:
Awesome, thanks for explaining, im easily confused with this stuff haha!

Yeh i must admit i am torn between the Gk mb500 / mb fusion and the 700RB II...

Id of course love the lightes one.. but most reviews say the mb500 is lacking vs the 700rb II... so i guess its a toss up between the mb fusion and the 700 rb II
Click to expand...

The fusion500 and MB500 put out about the same volume from my limited trial with them. Pretty impressive, and at most, just a smidge behind the 700.

One thing to consider is that the Fusion, while you can push the tube preamp to overdrive, does not have that classic GK grind that is inherent in the 700 and MB500. If I was rockin', I'd probably go with the MB500 (or the mighty MB800 if you really were pushing some big cabs at high volumes, or where using a singl 8ohm large cab like a 410, where you could use high 8ohm wattage). The fusion is a bit clearer and smoother in voicing to my ear.

I actually prefer the fusion, but I like it very clean and more even than the aggressive, grindy 'in your face' tone of the MB500 or 800.
 
#13
Brilliant thanks for the info..

I play in a hard rock band needing to cut through to guitars, i like a crisp / punchy aggressive sound hence why i think imf svouring the 700 RB II.

Which would you recommend between the 700 and the mb 500? :)
 
#14
I will say that the 700RB cuts through the mix like a knife, ridiculously loud too. From what I understand the MB's preamp is pretty much the same, maybe a little smoother. Can't go wrong either way, GK is known for it's signature sound and reliability
 

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