Matching cabs- yet again.

[M4L666]

I have an Ashdown Little Giant 1000- 2x500w outputs @4 ohms. Is it safe to run one 350w, 4ohm cab at low volumes? What about two of those? What about high volumes? Do I need to buy new cabs?

[BottomEndian]

You'll be fine. Don't push the volume up and everything'll be sweet. They might start farting a bit if you push up, but they're surprisingly abuse proof, those cabs. I should know!

Edited February 18, 2010 by BottomEndian

[M4L666]

They've served me well well, my ears. Dunno about my back, mind

[JTUK]

Be very careful about these mismatched limits..IMV

In an ideal world I'd double the cab rating compared the amp output, but this isn't possible in this case..
Of course, it is possible to run just one side of the amp if you can stay at low volume, but if you are gigging or rehearsing it could get
difficult..
Bass can be brutal on speakers when driven hard
You know the problem and the consequences, it is just a question of how controlled you can keep it all...

[Phil Starr]

So long as you keep the sound clean you will be fine. Your average sound is only a fraction of the peaks. A 10dB headroom means you are running at an average of less than 50W. If you run into 'fart' territory or use a lot of effects though all bets are off

[warwickhunt]

Honestly stop worrying. I've driven the same 350w PA cabs [u]hard[/u] (i.e. a whole 4 piece pub rock band inc drums) with a 1200w power amp (but never with anything going into clipping) for 15 years with not one bit of a problem, I've also used 200w bass cabs with 1000w power amps and conversely a 1600w bass cab with a 150w amp and so long as you listen to what the cab is doing you won't come to any harm. The odd fart/noise from your drivers and they are telling you something is working too hard and you need to adjust something accordingly... just use some common sense.

Oh and in 30+ years of playing all sorts of music through all kinds of bass cabs whilst owning and being in charge of all manner of PA systems I've only ever had one speaker fail... and that was a new driver at 'house' volumes, so it was the driver at fault not the use! Oh Oh I've said it now.

[M4L666]

The problem is finding 500w cabs, I guess. They seem to be working fine, but I'll keep my ears open. Ideally, when buying a new cab, I should go for the same or above wattage of the head, right?

Edited February 19, 2010 by M4L666

[BottomEndian]

[quote name='M4L666' post='750570' date='Feb 19 2010, 09:49 AM']The problem is finding 500w cabs, I guess. They seem to be working fine, but I'll keep my ears open. Ideally, when buying a new cab, I should go for the same or above wattage of the head, right?[/quote]
I think part of the problem you've got here is that you've got 4-ohm cabs. If they were 8-ohm, you'd be much more likely to find a head that was perfectly within acceptable printed parameters with them. IIRC, if the head puts out 500W into 4 ohms, it'll put out about 350W into 8 ohms. The alternative is to find a head that's happy at 2 ohms with an output of 700W or less. Something like the Peavey Max 700.

[chris_b]

I use my 500 watt amp and 300 watt cab together. There's no problem as I only have the amp on 2. For loud gigs I use 700 watts of speakers and the same amp on 5 and for very loud gigs 1400 watts of speakers. I've never had a speaker fail as I don't thrash gear and prefer everything to be working well within its limits.

[BottomEndian]

[quote name='warwickhunt' post='750533' date='Feb 19 2010, 09:10 AM']Honestly stop worrying. I've driven the same 350w PA cabs [u]hard[/u] (i.e. a whole 4 piece pub rock band inc drums) with a 1200w power amp (but never with anything going into clipping) for 15 years with not one bit of a problem, I've also used 200w bass cabs with 1000w power amps and conversely a 1600w bass cab with a 150w amp and so long as you listen to what the cab is doing you won't come to any harm. The odd fart/noise from your drivers and they are telling you something is working too hard and you need to adjust something accordingly... just use some common sense.[/quote]
IIRC, power amps and bass amps tend to be rated quite differently for output. Power amps have very low THD, and they're designed to stay clean all the way up to maximum volume. Bass amps typically have higher THD at the power level they're rated at, and they're often designed to go beyond that level too. So they'll generally sound louder than PA power amps for any given power output rating because the distortion (which you probably won't be able to hear as distortion -- more of a "thickening") fills out the sound. I could be wrong about all this, but it's based on experience.

I used to use a Tapco power amp into one of these cabs that M4L666 has (running at 800W into 4 ohms at full tilt), and it felt [i]nowhere near[/i] as loud as the Peavey Max 700 (running 475W into 4 ohms at full tilt, but in practice nowhere near full tilt). Even my 500W LMII (which is supposedly ultra-clean) absolutely kicks the ass of the 800W Tapco into the Barefaced Vintage.

[ThomBassmonkey]

[quote name='M4L666' post='750570' date='Feb 19 2010, 09:49 AM']The problem is finding 500w cabs, I guess. They seem to be working fine, but I'll keep my ears open. Ideally, when buying a new cab, I should go for the same or above wattage of the head, right?[/quote]

Just get as high wattage as possible, can't go wrong that way.

There's loads of 500w+ cabs about, it just depends on your budget and other preferences.

[elliswasp]

As far as running lower wattage cabs on high power amps there is no problem it is better to do things that way than have cabs that want more power than your amp can give asuming you dont just turn everything up to eleven and play lol. If your cab requires more power you may well find yourself running the amp at a level that it is not happy with and subequently kill the thing well before its time. If you have an amp that is rated higher than your cabs you will have head room the amp wont struggle and it will be much happier running a smaller cab using less power. You will obviously have to listen out for signs of stress on your speakers as they will tell you when something isnt right but other than that there should be no problems.

if your amp is rated at 1000w at 4ohms then you cant put two 4ohm cabs threw it if you do you will run the very serious risk of blowing your amp up. your choices are simple either change your cabs/speakers for two 8ohms cabs rated at anything up to 500w per cab personally i would have them at about 350-400 for the sake of head room or run the single cab and keep the volume down far enough that the cab isnt complaining about it.

By the way if you are happy to try this i wuld have a look at the 4x10 cab you have and see if you could re wire it to run at 8ohms this is easy to find out if you pull one of the drivers out of the cab and check its ohm rating on the back you will be able to determine if you can re wire it or not if the drivers you have in the cab are all 16ohms then you can do it if they are not then you would need to change the units and it would prbably start to get expensive. If you can re wire then then you only need to find an 8ohm 15" driver for the other cab that would be a nice cheap way of running your two exsisting cabs with very little outlay.

Markus

[BottomEndian]

[quote name='elliswasp' post='753650' date='Feb 22 2010, 12:03 PM']By the way if you are happy to try this i wuld have a look at the 4x10 cab you have and see if you could re wire it to run at 8ohms this is easy to find out if you pull one of the drivers out of the cab and check its ohm rating on the back you will be able to determine if you can re wire it or not if the drivers you have in the cab are all 16ohms then you can do it[/quote]
Sorry, my brain may not be functioning properly today, and I'm mentally inserting my own punctuation in that, so I may have the wrong end of your stick, but... How can you wire up four 16-ohm speakers to give 8 ohms total? AFAIK, you can wire them in parallel (4 ohms), series (64 ohms) or series-parallel (16 ohms). Is there another configuration I don't know of?

[elliswasp]

No your right worry had a bid of a momney there im not sure what i was thinking if your running a four ohm cab with four speakers there is no way of re wireing it up to make it an eight ohm cab sorry about that once again.

Markus

[pete.young]

[quote name='elliswasp' post='753650' date='Feb 22 2010, 12:03 PM']if your amp is rated at 1000w at 4ohms then you cant put two 4ohm cabs threw it if you do you will run the very serious risk of blowing your amp up. your choices are simple either change your cabs/speakers for two 8ohms cabs rated at anything up to 500w per cab personally i would have them at about 350-400 for the sake of head room or run the single cab and keep the volume down far enough that the cab isnt complaining about it.[/quote]

I don't think this is quite right. According to the manual, the LGs are 2 x 500 Watt into 4 Ohms, not 1000W into a single 4 Ohm load. What the OP probably needs is either a pair of 500W-ish 4 Ohm cabs, or two 350W-ish 8 ohm cabs. I suspect you wouldn't really notice the difference in overall volume between running each side at 4 or 8 ohm.

When I had a technical question about a piece of Ashdown gear, I emailed the support line and got an answer back the same day. I suggest that rather than guess, or spend a load of money on something you don't need, it might be worth doing the same.

[elliswasp]

[quote name='pete.young' post='754399' date='Feb 22 2010, 09:23 PM']I don't think this is quite right. According to the manual, the LGs are 2 x 500 Watt into 4 Ohms, not 1000W into a single 4 Ohm load. What the OP probably needs is either a pair of 500W-ish 4 Ohm cabs, or two 350W-ish 8 ohm cabs. I suspect you wouldn't really notice the difference in overall volume between running each side at 4 or 8 ohm.

When I had a technical question about a piece of Ashdown gear, I emailed the support line and got an answer back the same day. I suggest that rather than guess, or spend a load of money on something you don't need, it might be worth doing the same.[/quote]

If the amp was a two chanel amp then you would be right but i think you will find it is a mono amp and there for it is a 1000w amp it has two outputs so that you can run two cabs off of it from seperate outputs so that any one lead is not under to much load my ashdown amp has two outputs on it and they can run at four or eight ohms but i cant run two 4 ohm cabs on it if you run two four ohm cabs then the amp will run at two ohms and unless it is designed to the amp will not be happy and it will probably result in the amp failing.

if it turns out that the amp is a stereo amp which i doubt but its possible then running the two cabs will be fine but i would check that first.

Markus

[BottomEndian]

[quote name='elliswasp' post='757639' date='Feb 25 2010, 09:58 PM']If the amp was a two chanel amp then you would be right but i think you will find it is a mono amp and there for it is a 1000w amp[/quote]
Nope, it's a mono amp with two separate power amps, each running at 500W into 4 ohms, just like Pete said -- effectively two 500W bass heads in one box, both sharing a preamp and EQ stage.

[elliswasp]

[quote name='BottomEndian' post='757702' date='Feb 25 2010, 11:07 PM']Nope, it's a mono amp with two separate power amps, each running at 500W into 4 ohms, just like Pete said -- effectively two 500W bass heads in one box, both sharing a preamp and EQ stage.[/quote]

ok i didnt realise that if that is the case and it has two amps that share eq settings then there is no problem with running the two 4 ohm cabs on it then and as they are 350 each that will give you plenty of head room.

Markus