Using an amp more powerful than your cabs!

[jimbobothy]

Hi folks,

I've just got off here a couple of Markbass cabs (TRV 151 P and a TRV 121 H) both 8 ohm cabs rated at 400W. I've also got a Genz Benz Shuttle 6.0 12 T and am currently using the head of that to run them. As it seems that there are still a few Genz Benz bargains about at the moment would it be a no no to get a Shuttle 9.2 or Streamliner 900 and run it through these two cabs? If I used the pair I'd have 800w cab rating but the head would push out around 900w at full tilt (not that I'd be going that loud anyway). Also using a single cab I'd have an extra 100w too much going through the 400w cab.

I've also read you can use any head with any cab, just use your ears, also even a lower powered head can damaged a higher rated cab with the wrong EQing, and that a cab will mechanically fail (at the cone?) before the voice coils will overheat etc What should I listen out for to avoid damage etc etc . The world of amps and cabs have floated on by until recently as I've been too preoccupied with that 'perfect' bass search until recently !!

Any suggestions please?

Edited December 8, 2013 by jimbobothy

[Merton]

http://basschat.co.uk/topic/223670-underpowering-cabs/page__pid__2295318#entry2295318

[Lozz196]

Listen out for the amp struggling - difficult to put it into words but if the previous note doesn`t seem like it can get finished due to the next one starting is about the only way I can describe it. If you play clean, if the cabs get very fuzzy is another way of keeping an ear out.

If it were me I`d stick with the 600 watt version to be safe, I can`t see the need for 900 watts, but with the 900 watt set-up I`d be surprised if your ears could take it running the amp at too much for the cabs. I really think you`d give out before the cabs.

[chrismuzz]

It 'should' be ok if you listen carefully, but I'd never do it.

[xgsjx]

Ignore the watts, use your ears. That goes for any amp into any cab.

[LukeFRC]

and going on another thread - don't lend it to anyone!

[jimbobothy]

[quote name='LukeFRC' timestamp='1386533071' post='2301190']
and going on another thread - don't lend it to anyone!
[/quote]

Lol!

[Muzz]

I run a 900w Streamliner into an 800w-rated cab, never given it a second thought. I listen to what I'm playing, and I'd hear the thing struggling. The only time I'm cautious is when I use the octaver. I guess if you use heavily distorted or driven tones it'd be harder to spot, though.

[JTUK]

Not sure you can count on hearing it struggle... if the numerous threads about people not being about to hear the cab
and off-axis issues.

But then saying a cab can take 300w is just as vague... you wouldn't get so many blown speakers if that was the case. IMO

[gafbass02]

Having owned those cabs and that head I honestly don't think you'll have a problem.
I'm not convinced the genz rating is terribly accurate. I'd say go for it and just be mindful

[gsgbass]

listen to the speakers. If you run an over wattage through A cab, at higher volumes especially, if you hear what sounds like a [b]growling gurgle[/b] sound, you'r pushing it to hard. If at all possible, stay within your wattage perimeters from head to cab.

[discreet]

Maximum wattage ratings are not an accurate indication of amp 'power', anyway.
It's very unlikely you will have a problem.

[Pbassred]

I was expecting a lot more technical opinion to jump on this thread early. You're fine.
The first limit of a cabs capability is its ability to cool itself. Speaker driver ratings are the same ones used for DJ speakers which run heavily compressed full range music all night. That limit assumes that you are delivering is RMS value constantly. If a bass player does that, he's a poor player.
Secondly, as the speaker coil gets warm. its resistance increases. The increases in resistance causes a reduction in current - power.
Thirdly, you run a 800w amplifier full on all night?
Forth (and some technical backuo required) The physical resistance to moving air within the cab must cushion and therefore protect it.
fifth - no one can hear the difference between 800 and 900 watts anyway.
Sixth - your amp's PSU will probably sag before your speaker does.

[Bill Fitzmaurice]

[quote name='jimbobothy' timestamp='1386522066' post='2300992']
Any suggestions please?
[/quote]If it farts out turn down.

[Dave_the_bass]

Rather than 900 watts; why not go to the 12.2?

2 x 600W @ 4ohms power amps (375W @ 8ohms) so within the power rating of your cabs and you can always add another two of them if your guitarist starts getting ideas above his station. Nothing says "turn your f***in amp down" like liquefied internal organs!

[chris_b]

It doesn't matter what the amp is rated at, it could be a million watts, it's the volume you're putting through the cabs that counts. So, just because you want to use a higher rated amp why will that make you play it louder than your current amp?

You don't say anything about running out of power with your current amp, so given that most people who up rate their amp will stay at the same volume, the extra watts will only give you more headroom, which will get you better tone and give the amp an easier work out in the process.

Anyway you were probably running your 600 watt amp at a lot less than half power so your cabs won't be in any danger.

[chris_b]

If you like the tone of the STL 6.0 get the 9.2.

It's more of the same with a much, much better and fuller low end.

The SLR series doesn't sound anything like the amp you have.

[Phil Starr]

OK it has been explained before but here's the technical bit.

Amps are really simple to measure, Their wattage is just a measure of the electricity they can pump out. Connect them up to a resistor, turn them up to the point of distortion and measure the voltage and current. There are variations but the 'RMS' wattage is basically that simple.

Speakers are more complex, their failure is caused three ways, By overheating, by over excursion and by wear and tear. The ratings of speakers are based on over-heating only. The measurement technique is simple enough, plug a few samples in turn up the power and see if they burn out, then try higher powers until they do. the last power at which they all survives is the rating.

the trouble is that it tells you little about the real world performance. Your cab will have a different rating in Kyoto in the summer to Reykjavik in the winter for instance. The amount of stuffing in the cab is probably more significant in affecting cooling but the biggest factor is the type of music you play, Gaps between notes reduce heating, lots of sustain and distortion increase it.

Compression is a particular killer. The heating effect is about the average power you are using. If your peaks are 100W and you have 40dB of dynamic range between your quiet and loud bits your average power is only 1W (yes one watt) with a more realistic 20dB range it would be 10W. (this all assumes you don't have any gaps in your playing so in reality the average would be less) Extreme compression can bring the average very close to the peaks, though of course it will sound louder and you would probably turn down. Used normally though it is unlikely that the 10W average power is going to burn out your 100W speaker.

Much more likely is damage through over excursion, here bass is a problem just as much as power. If the coil moves out of the magnet it won't cool efficiently. If it moves too far in some designs it will hammer against the back of the magnet. The more power and the deeper the note the further it moves. The air in the cab asts as a damper on the movement but if you have a ported cab there is another complication, below the port tuning the air doesn't damp the movement and your 400W cab might only be able to handle 40W.

So practically what does all this mean? Firstly that no-one can definitively say whether your cab will be safe, we don't know how you play. Most people don't regularly blow 300W speakers with 300W amps. If you use a lot of bass boost and fx pedals then you probably ought to be more careful than if you go for a clean sound. If you only match the acoustics of the drums then there really shouldn't be a problem with this level of amplification, you almost certainly aren't going to turn these amps anywhere near full up. If you are trying to drown out two Marshall full stacks then beware. for one thing you won't hear a farting cab because of your hearing loss.

Finally don't rely on hearing the speaker distortion, for one it is often already too late by then but mainly because, although that sound is really clear in your bedroom or a rehearsal room, on stage it can be really tricky to realise it is your rig that is making the awful noise.

[jimbobothy]

Hey cheers again guys, lots of stuff to consider. Just to let you all know I don't use any effects or compression but I am after a slightly more warmer sound, hence the streamliner over the shuttle. Oh and I don't need the volume that my 600w amp pushes out normally, however if I've got the option of lots of headroom available with a less strained amp I think I'll go for that at some point, thanks peeps

Edited December 9, 2013 by jimbobothy

[chris_b]

For more warmth in your sound I'd also check out the Markbass LM3 or even an Aguilar TH500.

[Damonjames]

Can't see any real danger or issues, as long as YOU are aware that this approach carries some risk. Having the extra room on the dial may be tempting at times!
Also may be worth reading the thread about the guy who was in a similar situation as you and let another bass player use his rig at a gig..... He now has a blown driver in his cab for the priveledge!

[Conan]

[quote name='Pbassred' timestamp='1386540864' post='2301336']
Speaker driver ratings are the same ones used for DJ speakers which run heavily compressed full range music all night. That limit assumes that you are delivering is RMS value constantly. If a bass player does that, he's a poor player.
[/quote]

A bit unfair perhaps? If the music/band/situation calls for it (and it could happen, I suppose!) then surely that makes you a good player? Doing what is required?

Just a thought!

[gsgbass]

[quote name='chris_b' timestamp='1386611242' post='2302166']
For more warmth in your sound I'd also check out the Markbass LM3 or even an Aguilar TH500.
[/quote]

The Markbass Little Mark lll is a solid kicker.
[IMG]http://i.imgur.com/pWgl17T.jpg[/IMG]

Edited December 15, 2013 by gsgbass

[jimbobothy]

Hey guys, I went for the Genz Benz ShuttleMAX 12.2 in the end. Had to send it back due one of the power socket securing clips breaking when I took the power lead out, they make the fit very tight to avoid it rattling out in use, however this one was a bit too tight lol! Saying that I'm getting a replacement and think I'll be very happy with it. Basically using it due to the 2 channels, I like the FET for fretless stuff and the Tube for a bit of grit on my fretted. I also won't be going over the cab limits and don't think I'll need to push it so hard that there would be a risk of clipping. Another point, if I get 2 more 8 ohm cabs I'll have a big stack, and 1200W to play with ! Cheers for all the advice anyhow

Edited December 18, 2013 by jimbobothy

[Dave_the_bass]

[quote name='jimbobothy' timestamp='1387212214' post='2309444']
Hey guys, I went for the Genz Benz ShuttleMAX 12.2 in the end. Had to send it back due one of the power socket securing clips breaking when I took the power lead out, they make the fit very tight to avoid it rattling out in use, however this one was a bit too tight lol! Saying that I'm getting a replacement and think I'll be very happy with it. Basically using it due to the 2 channels, I like the FET for fretless stuff and the Tube for a bit of grit on my fretless. I also won't be going over the cab limits and don't think I'll need to push it so hard that there would be a risk of clipping. Another point, if I get 2 more 8 ohm cabs I'll have a big stack, and 1200W to play with ! Cheers for all the advice anyhow
[/quote]

Good move. See my earlier post!

My rig's in the gear porn/show us your rig.1x4ohm and 2x8ohm cabs!