andy_s Posted September 17, 2003 Share Posted September 17, 2003 I need to provide a small sound system (200 - 300W ish) that can be mounted on a trolley and pulled along as part of a procession. does anyone have any hints about small gennies or batteries?? any suggestions gratefully received! Link to comment Share on other sites More sharing options...
peter Posted September 17, 2003 Share Posted September 17, 2003 Most "household" gennies should cope with 200/300w. Beware about earthing though - obviously you can't earth a moving PA system. Link to comment Share on other sites More sharing options...
Matt Posted September 17, 2003 Share Posted September 17, 2003 well, you can get the computer backup things, ups (they usually provide some power, though what your using it for, you could be talking like £1k's to buy it, which probably aint within your budget) just have a load of car batteries connected in PARALLEL (emphasis on that, or you will bugger it all up) and get a 12dc to 240v ac inverter, the usually cost between £50-£300, depending on the amount of wattage you need to draw, sound like you will need a 400w inverter, if you do choose this method, ...remember connect 2 or 3 car batteries of the same rating in PARALLEL, eg connect all the positives together, and all the negatives together, then connect the inverter to them. this can provide you with several hours of fun if they are fully charged car batteries, ...and you could always make it a permanent rig, and have the batteries charging over night, if you wanted of course Link to comment Share on other sites More sharing options...
James Posted September 17, 2003 Share Posted September 17, 2003 what does the sound system have to do? Link to comment Share on other sites More sharing options...
themadhippy Posted September 17, 2003 Share Posted September 17, 2003 those computer back up thingys (uniteruptable power supply) might be a bit "noisy" for pa use,they dont genarate a very nice sine wave,same with cheap inverters. Link to comment Share on other sites More sharing options...
richard Posted September 17, 2003 Share Posted September 17, 2003 Studiospares sell a fender 'passport' system for around £400, which has speakers, mixer and amp built in and will run from a 12v supply I think. If you don't want to buy I'm sure that somewehre will hire something similar Link to comment Share on other sites More sharing options...
dominicgross Posted September 18, 2003 Share Posted September 18, 2003 You may want to talk to terry tew (www.terrytew.co.uk) They hire the passport systems.... Link to comment Share on other sites More sharing options...
Brian Posted September 18, 2003 Share Posted September 18, 2003 just have a load of car batteries connected in PARALLEL It's actually not a good idea to connect any batteries in parallel. Unless they are designed for it. Link to comment Share on other sites More sharing options...
andy_s Posted September 18, 2003 Author Share Posted September 18, 2003 Thanks for all the suggestions: plenty to think about. It's for an outdoor (!) parade- type event (hence the lack of a handy 13A plug....) and the idea is to give four vocalists a bit of a lift to get them over a couple of saxes and some drums (no amplification). We thought of giving them megaphones, but they are pretty expensive to buy for a one off event, and make the voices sound funny. We are planning to use good old 58s on short mic cables rather than risk any problems with radio mics - we won't get a chance to practice / troubleshoot in the actual location. The sort of things I would like to know are: what is the answer to the earthing issue raised by Peter: - are there any specialist gennie suppliers who can supply nice smooth electricity or do I go for building site technology and some kind of supply cleaner? I will look into the 12V portable PA - thanks for the tip. The only battery stuff I've so far found only gave about 40W of power, which I thought would be a bit weedy given the ambient...there will be other participants in this parade, all no doubt making plenty of noise in one way or another! Link to comment Share on other sites More sharing options...
Andrew C Posted September 18, 2003 Share Posted September 18, 2003 In the past I've done precisely what you're proposing. Radio mic, pre-amp, switch mode power amp and a pair of Bose 402s. The whole lot ran off a bog-standard Honda generator (no idea of the rating, but it was v. small). Only once had a problem with the radio mic when we failed to run the geni at full speed. Earthing is a good point, I used a 10ma 10ms RCD. Link to comment Share on other sites More sharing options...
Matt Posted September 20, 2003 Share Posted September 20, 2003 earthing has nothing to do with the rcd's does it, I thought they were only for cutting off power in the live and neutral lines if too much current was drawn, and the rating was response time and current. The point of an earth wire is to let the current flow away and trip the rcd if anything happens, you usually find the eath cables connected to pipes etc... around the house and then a earthing stake driven into the ground somewhere, sometimes in a garage, by the front dor under a cover, or in the back garden. please inform me if the above statement is incorrect...? when we used a generator we just used a 1 inch thick solid copper stake driven into the ground, about 2 feet, and a high current wire connected to the earthing point on the genny... not possible for what your doing anyway. edit was spelling mistake... Link to comment Share on other sites More sharing options...
Bryson Posted September 20, 2003 Share Posted September 20, 2003 You're getting you're RCDs mixed up with your MCBs. RCDs trip as a reaction to current in the earth wire (of a certain ammount and duration)MCBs trip as a reaction to the current in the live wire. (Or in both the live an neutral in a double-pole) It's slightly more complex than that, (involves things like thermal sensitivity) so if anyone else wants to clarify/correct, feel free. This might help further. Link to comment Share on other sites More sharing options...
Tomo Posted September 20, 2003 Share Posted September 20, 2003 just have a load of car batteries connected in PARALLEL It's actually not a good idea to connect any batteries in parallel. Unless they are designed for it.And often even then! I was at an event last year where someone was charging a set of nicad batteries in parallel and set fire to them! It's remarkably easy to do if you don't have an automatic charger.Also, Lead-Acid batteries *can* reverse polarity if overdischarged or abused in other ways, which would lead to interesting things obviously...(The really big UPS setups have all kinds of clever isolating and charging circuitry to protect them from this) If at all possible, use a single battery big enough to do the job! However, car-type batteries aren't designed for deep discharge or cyclic use (few lead-acid chemistry are), so won't keep capacity for more than a few charge/discharge cycles.A cyclic use battery is pretty expensive in itself, and they usually need a specialist charger at ~£150 or more. (The branded charger for Hawker Genesis batteries is about £350!) My personal feeling would be to use a small generator - Screwfix do a 650W one for £250, and I expect you can find a local supplier who can get one cheaper or would hire something out.Dunno how good the output from one that size would be though. Sound equipment is a bit more sensitive than domestic lightbulbs! Link to comment Share on other sites More sharing options...
gareth Posted September 20, 2003 Share Posted September 20, 2003 Moderation - 21/9/03, 00:48 - references to drugs deleted. Link to comment Share on other sites More sharing options...
gareth Posted September 20, 2003 Share Posted September 20, 2003 earthing has nothing to do with the rcd's does it, I thought they were only for cutting off power in the live and neutral lines if too much current was drawn, and the rating was response time and current. The point of an earth wire is to let the current flow away and trip the rcd if anything happen{Ding} Contradiction! Earthing has everything to do with RCDs, as Bryson has already said. RCD stands for 'Residual Current Device' - they work by detecting an imbalance between current flow in the live and neutral conductors of a circuit, if there's an imbalance the little device assumes that the missing current is going to earth (quite probably via an electrician whose hair is starting to look like Billy Whizz!). If this current imbalance is greater than the rating of the RCD (usually something around 30mA), then 'pop'! Out comes the trip, within the rated response time. Link to comment Share on other sites More sharing options...
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