Help please from experts. Slightly mismatched cabs.

[karlfer]

Cab one, 400 watts, 8 ohms
Cab two, 350 watts, 8 ohms
Both from same manufacture. Both same speaker config, just the updated model is rated at 350 watts rather than 400.

Now I'm sure I read somewhere that in this circumstance, one of the cabs will get more juice from the amp, in this case a 500 watt Markbass.

Can somebody explain it to me please. Bare in mind I make an average 4 year look like Mensa fodder.

Cheers,
Karl.

[GregBass]

It's all in the impedance. If the cabs have the same impedance, they will dissipate the same power from the amp. That does not necessarily mean they will sound as loud - that depends on a host of other factors - but the power taken from the amp will be the same.

[Roland Rock]

I'd have thought that they would each receive the same amount of juice from the amp, but (going on those ratings) one cab can handle it better than the other.
However, bare in mind the golden BC rule, "Thou shalt take cab watt ratings with a pinch of salt"

Edited May 12, 2015 by Roland Rock

[Truckstop]

Both cabs will get 250w. There will be no issues or problems at all. Even if you run the amp at full chat, neither of them will receive enough watts to cause any damage and they'll both get the same amount.

However!

I'd assume that different drivers are being used in each cab to cause the disrepency in power handling? Hopefully they won't sound too different.

Edited May 12, 2015 by Truckstop

[karlfer]

Jeez, what kept you all, only 4 replies in the 1st 6 minutes

Thanks guys, told you I was a bit 40 watt

[Roland Rock]

[quote name='karlfer' timestamp='1431428793' post='2771158']

Thanks guys, told you I was a bit 40 watt
[/quote]

Yeah, but they are top quality valve watts ;-)

[karlfer]

[quote name='Roland Rock' timestamp='1431428905' post='2771161']
Yeah, but they are top quality valve watts ;-)
[/quote]

Thank you Mr. Rock, very kind.

Many years ago I was in the office of the company I worked for at the time. It was in Godalming.

I said something and one of the girls said "you're a bit 40 watt".
After asking, she explained it meant dim.
Never bought her an ice cream again

[Japhet]

My understanding is that the Watts quoted is only in relation to the speakers ability to dissipate heat which won't make any difference to how loud they are or well matched for that matter, unless you're pushing them both to the limit.

[Bill Fitzmaurice]

[quote]Both cabs will get 250w.[/quote]That's probably not the case. Power distribution is a far more complicated issue than simple division. For that matter power delivery into a single cab isn't a constant. It varies with impedance, and impedance isn't a set value, it's different at every frequency. A typical 8 ohm rated speaker will have an actual impedance that may range as low as 5 ohms and as high as 50 ohms.[quote]Even if you run the amp at full chat, neither of them will receive enough watts to cause any damage .[/quote]Also not the case. Most speakers cannot take anywhere near their thermal rating before mechanical damage is a possibility. Most amps can put out at least four times their rated power for short duration peaks, and most will put out twice their rated power long term with high THD, as their power ratings are measured at low THD.
The key to preventing damage is simple enough,though. If the speakers distort, turn it down.

[karlfer]

Thanks guys.
The reality is the particular 500 watt Markbass head, at gigging volumes, will probably have gain at around 3 o'clock, touch of compression, bass, mid, treb around noon and colour also around 3 o'clock.

HOWEVER, Master Volume is unlikely to go past 9 o'clock as I do not like bleeding ears Gain up high because it's sounds wonderful there.

My concern was that with two cabs, both 8 ohm, one 350 watts, the other 400 watts, that I was potentially going to cause damage to the speakers in one box.

Many thanks Bill Fitzmaurice, I know you have amazing knowledge of this stuff for obvious reasons

Edited May 12, 2015 by karlfer

[Truckstop]

[quote name='Bill Fitzmaurice' timestamp='1431432866' post='2771242']
That's probably not the case. Power distribution is a far more complicated issue than simple division. For that matter power delivery into a single cab isn't a constant. It varies with impedance, and impedance isn't a set value, it's different at every frequency. A typical 8 ohm rated speaker will have an actual impedance that may range as low as 5 ohms and as high as 50 ohms.Also not the case. Most speakers cannot take anywhere near their thermal rating before mechanical damage is a possibility. Most amps can put out at least four times their rated power for short duration peaks, and most will put out twice their rated power long term with high THD, as their power ratings are measured at low THD.
The key to preventing damage is simple enough,though. If the speakers distort, turn it down.
[/quote]

Happy to be corrected

[JTUK]

[quote name='karlfer' timestamp='1431428197' post='2771140']
Cab one, 400 watts, 8 ohms
Cab two, 350 watts, 8 ohms
Both from same manufacture. Both same speaker config, just the updated model is rated at 350 watts rather than 400.

Now I'm sure I read somewhere that in this circumstance, one of the cabs will get more juice from the amp, in this case a 500 watt Markbass.

Can somebody explain it to me please. Bare in mind I make an average 4 year look like Mensa fodder.

Cheers,
Karl.
[/quote]

Wouldn't worry about it... you have enough in hand over the amp output to load balance ok
and you'll never get to run the amp really really hard, I doubt...when the amp will strain before the cabs ..??.
I'd just make sure I could hear any stress on the cabs when getting used to the set-up of amps/cabs

[karlfer]

Thanks everyone.
It's not going to happen due to a lack of interest in my MB cabs on here, and the Facebook dreamers driving me nuts

Never mind, seemed like a good idea at the time