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Rdogg View Drop Down
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    Posted: 03 February 2017 at 3:29pm
Hello everyone, I'm looking to buy a generator for my rig but I have absolutely no idea what size and what make to go for.

From what I'm told I need to go for diesel because it's quieter, mor efficient and also they can be filled while running as opposed to petrol which can't. As for power I'm running-
Matrix mf7000
Matrix xt2000
Stanton 1600
Dbmark XCA 2/4
Dj desks of some sort (it'll vary)
Mixer
Laptop
Phones etc

From what I'm told I need to get the same Kva as the amount of W my system will use but according to my amps alone that'd be over 10,000 and a 10kva diesel Honda generator according to their website doesn't exist and I've seen bigger rigs being run of portable generators as opposed to trailer gennys.

If someone could shed some lights and chuck some maths at me and help me understand that'd be much appreciated(: I've done some googling but now I'm more confused
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WILLZTHRILLZ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WILLZTHRILLZ Quote  Post ReplyReply Direct Link To This Post Posted: 03 February 2017 at 4:45pm
Hi Rdogg, to run some serious amounts of audio out, ye will need some serious power in.
If ye add up all, and I mean all yer equipment and then double it then you have some headroom. 
That amount of equipment plus lights etc plus future proofing for more gear, ye would need somewhere around 25 kva diesel gen. Thats what I would say that you need. ye could probably pick up a diesel genny from 2.5 to 4.5 thousand.   Sorry, but you will be better with soundproof cabinet and definitely one fitted with '' Deep Sea Controller'' ( these can be retro fitted to older generators)
I feel sure that one of the more experienced people in this field here will be along soon to further discuss this.
Cheers
Will
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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddymendez Quote  Post ReplyReply Direct Link To This Post Posted: 03 February 2017 at 6:01pm
you probably won't need as much as you think you'll need, your amps figures are likely to be inflated and of course they won't be drawing the full amount for the full time, like say a heater or a light would.

you'll probably be okay with a 6.5kVA diesel (go for one with yanmar, lombardini or lister engine, and meccalte, sincro, markon alternator). but i'd look at switching out that matrix mf because without PFC it will draw big peaks which could limit you somewhat.

by the way you can fill a petrol genny whilst running but i wouldn't recommend it. however petrol are a lot cheaper and you can get higher output for your money. maybe you could switch off momentarily to fill up? (heh ;))
couple it with one of these and you can box off filling it up really quickly:
http://www.ebay.co.uk/itm/Jerry-Can-20-Litre-Fuel-Diesel-Petrol-Oil-Water-Spout-Black-20L-Container-NEW-/190826126359?hash=item2c6e1f9c17:g:ORIAAOSwGOxXAioR

if going petrol look for honda gx390 for 6kva output, or honda gx610 or above for around 10 kva.  loncin engines are also good. again look for meccalte alternator or one of the above i mentioned.
120-140 bpm, pianos and bass.
diesel, the fuel of professionals.
mendez/manchester
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2017 at 4:38pm
The problem with petrol gensets, is the revs will change with load, affecting frequency, as much as voltage. Fine for small, constant loads, nasty for anything above 1KW.

Diesel sets change torque output to drive changeing loads, so steadier revs, and hence frequency. Smallest Diesel commonly available tend to start from 6KVA. Max of 32A, realistically less, say 25A at 220-240V. For your lot, and nothing else (see later) I would reckon 10KVA as a minimum.

Many events, float based type stuff, will insist on diesel, as safer than petrol. Diesel takes some igniting, very deliberate action or great stupidity is normally required, whereas look at a petrol spillage, and it will ignite.....

Get big. They are often quieter, which is always of benefit. Amplifiers, even with PFC, are nasty loads. What you need to do is dump at least 25% of available generator power into a purely resistive constant load, traditional Tungsten Par64 x lots, security lighting, or, at festival level, load banks (think giant hairdryers). This resistive power demand, dilutes the nasties being drawn by the amps and other SMPSU, and brings the power factor back towards 1.

The reason why generators are rated in VA, and not watts, is down to power factor. A power factor of 1 means the Voltage AC waveform, exactly matches the current AC waveform. In which case Watts=VA. However, as PF goes less than 1, current is not in sync with voltage, and Watts available= PFxVA.

Most gadgets and electronic widgets claim a PF of better than 0.95. However, like many things, many are guessing, or just down right lieing. Equally, amps are horrible loads, themselves driving horrible loads, doing some silly things, so no great surprise that most draw power equally awkwardly.

Read BS7909 for earthing, MCB, RCD, RCBO, cable sizes, etc. Too tired for that again.

Just because you have seen others doing more with less, doesn't make them right, just lucky. Equally, do not believe forums and other sources of BS. What will happen, is you find someone to tell you what you want to hear, which rationalises in your mind that it is OK to do what you want to do. Only verified sources should be trusted.

BS7671 has recently changed its wording from "competent" person, to "skilled". Knowing isn't enough (competent; has a piece of paper...). Skilled implies (and this is open to debate) competent (piece of paper) and experience, and real world knowledge.

Last time I used a genset, it was a 6KVA diesel, and all that was running was a QSC4050 at 4ohm/ch, dj mixer, cd player, and 8 RGBWAUv LED cans. Still wanged up 1KW of tungsten...Quite a nice bit of kit with a seemingly accurate meter for V, PF, Hz and I (verified with my meter...), but still got it out of idle with constant resistive 1KW load, and assumed that would help dilute any PF nasty from sound system, and LED SMPSU.

If your going to invest, do it once and do it properly. Any mistakes with gensets lead to death and damage.
Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
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Rdogg View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rdogg Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2017 at 10:22pm
Okay thank you everyone I'm definitely going for a diesel and unfortunately I'm not going to be swapping the matrix and I'm only going to be adding so yes 10-25Kva will be the one. 2.5-4.5g is fine to be paying I don't mind, and I'd rather buy big and properly first time. I will do some research on makes, does anyone know any which would be suited to electrical equipment that's 10-25kva?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rdogg Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2017 at 12:24am
Also will I be able to run all of that off the mains? The amp states 32a but mains are 13 or 20a so im confused. Can I use an extension cord or two and plug all those amps and shit into the mains in a normal house?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote krazyneil Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2017 at 3:08pm
it will all work fine off domestic sockets
GOD TOLD ME TO DO IT !!!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jasonstry Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2017 at 5:22pm
For about £10 or so you can buy a meter that plugs into a wall socket and that has a socket for you to plug into. You will find them on Amazon and ebay. They aren't exactly precision instruments but they will give you a good idea of the voltage available and how much power you are drawing. Most people are amazed (and, often, a bit disappointed) to learn how little power their gear is using. I have bought several of these as they keep vanishing at gigs.... 
Down with signatures!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2017 at 8:17pm
Originally posted by Rdogg Rdogg wrote:

Okay thank you everyone I'm definitely going for a diesel and unfortunately I'm not going to be swapping the matrix and I'm only going to be adding so yes 10-25Kva will be the one. 2.5-4.5g is fine to be paying I don't mind, and I'd rather buy big and properly first time. I will do some research on makes, does anyone know any which would be suited to electrical equipment that's 10-25kva?

Originally posted by Rdogg Rdogg wrote:

lso will I be able to run all of that off the mains? The amp states 32a but mains are 13 or 20a so im confused. Can I use an extension cord or two and plug all those amps and shit into the mains in a normal house


Are you serious? Your about to invest £4+k in some poor gen set, and you have never heard of a cee form.

Let alone a red one? I am guessing your gonna use 0.75mm^2 to link it all up too?

Tell you what, include me in your will. And get some life insurance. In return, I will design you a way to pull 26A from two 13A sockets to one 32A cee form outlet. Known as a widow  maker....


Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
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shagnasty View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote shagnasty Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2017 at 1:11am
Originally posted by freddymendez freddymendez wrote:

you probably won't need as much as you think you'll need, your amps figures are likely to be inflated and of course they won't be drawing the full amount for the full time, like say a heater or a light would.

you'll probably be okay with a 6.5kVA diesel (go for one with yanmar, lombardini or lister engine, and meccalte, sincro, markon alternator). but i'd look at switching out that matrix mf because without PFC it will draw big peaks which could limit you somewhat.

by the way you can fill a petrol genny whilst running but i wouldn't recommend it. however petrol are a lot cheaper and you can get higher output for your money. maybe you could switch off momentarily to fill up? (heh ;))
couple it with one of these and you can box off filling it up really quickly:

if going petrol look for honda gx390 for 6kva output, or honda gx610 or above for around 10 kva.  loncin engines are also good. again look for meccalte alternator or one of the above i mentioned.

Bolox!!!

Just BOLOX

NEVER use a shit-box genset with less VA cap than you amps have... END OF!!!

In real terms a 25KVA as suggested, is about where I would go, you list 10.6KW of cheap SMPSU amps that will cause havoc with a most gensets due to something called current distortion, I would go 20KVA plus with decent AVR ( the Deepsea kit looks after the engine and monitors the rig but still needs a decent AVR, in real terms DSC has no effect on power quality)  I would stuff 2x 3KW fan heaters (or 6 Mac500s) on the set to ballast load it (gens do 30> 80% load snatches really well, 0>50% very badly, give the system something to chew on (even really good sets have shite regulaution below 12%) also bear in mind a 20KVa set will have a 0.8 power factor (ish) so only 16KW, add to that teh agressive nature of your load (thinking Matrix def use 6 pulse inversion) you could easy see a 50% KVA > KW derate....

Get a decent machine and not replace it or yours amps every other gig...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote freddymendez Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2017 at 8:09am
I've done it many times before and will do many times again. In fact I've dumped 4 hogs and 2 turbo tms off an old lombardini 5kva and peeled people's faces off. The amount of power used is way less than people might think. 4.8kw odd constant is a lot of power - most people run everything off 13a mains anyway. So go drop ££££ on a massive genny but I'd first try a smaller set it at least measure properly the actual current draw of the rig.
120-140 bpm, pianos and bass.
diesel, the fuel of professionals.
mendez/manchester
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MattStolton Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2017 at 10:08am
Originally posted by freddymendez freddymendez wrote:

I've done it many times before and will do many times again. In fact I've dumped 4 hogs and 2 turbo tms off an old lombardini 5kva and peeled people's faces off. The amount of power used is way less than people might think. 4.8kw odd constant is a lot of power - most people run everything off 13a mains anyway. So go drop ££££ on a massive genny but I'd first try a smaller set it at least measure properly the actual current draw of the rig.

Originally posted by MattStolton MattStolton wrote:

Just because you have seen others doing more with less, doesn't make them right, just lucky. Equally, do not believe forums and other sources of BS. What will happen, is you find someone to tell you what you want to hear, which rationalises in your mind that it is OK to do what you want to do. Only verified sources should be trusted.

It is not about total power used. It is about the quality of the load, and the way it draws.

A Generator is not just a source of watts, it has inertia of spin, in both directions of speed/torque, there is a time delay between demand and fulfillment, and I have always had a nagging fear over Lenz's law consequences for creating spikes, both ways round. Faster the change/demand, bigger potential over shoot instantaneous spike....

Amplifiers, even with the worlds best PFC (Where is Victor when you need someone who will talk at length about the vagaries of an amp PSU!) are incredibly dynamic in needing power. Even the best, can only charge once every 1/50th of a second, yet are banging out near DC to 20K. And then the DJ drops something massive, and then stops it, does a rewind, and then drops again.

Generators like constant, and PA is not constant.

Something big allows you loads of spare, which you then have to use to generate wasted heat, in order to not fubar the gen set. As the gen set goes down, everything else will get burnt.

13A fuses are notorious for being quite "slow blow" in characteristic. Off a 32A B curve breaker/ring main, it is not outside the realms of possibility to trip the MCB before an aged, covered in carbon from repeated heating, 13A fuse. But everything will be starting to get melty. You can't get 4mm, let alone 6mm, in a BS1363 plug top, and a double switched socket outlet is rated to 19.5A, total, for 8 hours.

Whatever.

To use a Shagger's inspired phrase, you stick to doing things like you're in the third world, and I'll do it my way, and not trouble my PLI.


Edited by MattStolton - 06 February 2017 at 10:40am
Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
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