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12v bike rig - Advice needed! |
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CFLsound 
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Joined: 25 March 2021 Location: Bristol Status: Offline Points: 16 |
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 Topic: 12v bike rig - Advice needed!Posted: 25 March 2021 at 11:18am |
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hey guys, A group of us have decided to take the plunge on a 12v rig moved around on a trike. We've got a basic idea of what we want but could do with a bit of help on deciding what to go for in regards to the midtops, subs and overall design. Basically if anyone sees anything we mightve missed and could help us a little with ideas that would be wicked. Our budget is £1500 excluding the bike. Currently we have budgeted and weighed in: SUBS 2x Tham 12's (28kg) with B&C 12NLD76's MIDTOPS 2x Turbosound iP82 (18.6kg) AMP Pioneer GM-D9704 (3kg) If the amp is running at 60%, we have calculated that it will draw 6.24 amps. Idea is to run the speakers in parallel with the amp bridged, 1 channel for subs, one for midtops. We will then be powering a variety of stuff of an inverter including: Mixer (2kg) Laptop (1kg) Turntable (15kg) DSP (5kg) Inverter (3kg) Total daw of equipment on the inverter is roughly 11 amps with an 85% efficiency factored in for thngs drawn from the inverter and the laptop powered for 50% of the time. So rough total amperage is 17.24 amps. We've then set a goal of having an 8 hour party, so 17.24 * 8 = 137.92 ah so to only deplete AGM batteries to 50% we would need twice this capacity in our battery bank meaning roughly 280ah of batteries on board (50kg). So total weight is roughly 125.5KG. My friend who is a bike head reckons this is movable on a rickshaw type trike that we're looking for if we get the gearing and heavy duty frame right so we're not too worried about this. Yeha itll be a nightmare up hills but  it.So questions are! The midtops feel like a bit of a cheap option and we dont want to be victim of buy cheap buy twice so we are able to budget in £500 for a pair something else. We dont necessarily have to buy them off the shelf, so any designs which might be nice to build and give us a bit of scope fro some great drivers is also an option but we dont mind either way. We want it to sound great! Subs we have settled on tham 12's for efficiency and simple design. We have heard that MTH's kick a bit harder so this might be good as we arent looking to go super low as we cant carry the weight of bigger subs. Would it maybe worth going for 15" designs? We would also like to design a rig that is 12v portable at first buy also have the scope to potentially double the amount of subs so we can hold bigger parties without the bike and powered off mains. This is a future project so 12v is priority but it would be nice to think about this too. Does anyone have any experience with alternatives to AGM that are cheaper/lighter? Maybe second hand batteries? And finally, anyone see any glaring mistakes in our calculations? Parties will probably be shorter than 8 hours at first so we can monitor the batteries and power draw as we get to know the rig a little better. Sorry for the long post and loads of questions! We've got loads of banging info off here already so cheers for that, would just love a bit of final advice before we pull the trigger and try and get this thing ready for St Pauls  Nice one!
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imageoven
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Joined: 28 March 2007 Location: Scotland Status: Offline Points: 2186 |
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Posted: 25 March 2021 at 1:23pm |
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Presuming you are not going to be playing vynyl on the move, you could save a bit of weight by transporting the turntable seperately. I doubt you want it fixed to your speakers anyway? Personally I wouldnt touch a 2nd hand battery unless it was free.
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Keep pushing on, things are gonna get better.
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studio45
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Joined: 16 October 2007 Location: United Kingdom Status: Online Points: 3864 |
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Posted: 25 March 2021 at 1:42pm |
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Very sensible well thought out plan there, I like it. In general you will find the battery lasts longer than you thought it would powering an amplifier playing music. However that's mostly based on my experience of running everything else from low voltage and not using an inverter - they draw what they draw, continuously, so that will impact battery life.
My only suggestion would be to have a really good think about whether to use lithium batteries instead. Given that they're generally a bit happier with being run to nearly flat, you could use a 140AH battery and it would probably be less than 20kg. The cheapest way is if you buy prismatic LiFePO4 cells from Aliexpress and make up the battery pack with a BMS board yourself - a 4-series pack has a voltage window that works nicely with car audio gear and "12v" inverters. I know from experience that a 75kg trailer is pretty hard going and *barely* possible uphill in granny ring/Megarange sprocket. So 125kg seems like it will be right on the edge of usability. Disc brakes will be a *must*.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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CFLsound
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Joined: 25 March 2021 Location: Bristol Status: Offline Points: 16 |
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Posted: 25 March 2021 at 4:52pm |
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Cheers for the reply, yeah hadnt thought about LiIon, I have experience runnign stuff of car/lesiure batteries so it seemed like the easier option, can you link me to some of the LiIons you mentioned? Saw there was a post about them on another thread so will have a look at that too. Did you use mixers which are able to run straight off a 12v battery? I guess you could put a voltage regulator in between a car battery and mixer then modify the power supply from a 12v mixer too? I was a bit worried about voltage variance messing with equipment when depleting a battery so went for the inverter instead. And yeah cycling will be a slog! Were gunna think about converting to push bike to electric once we have a rig up and running to save our legs a bit. And like imageoven mentioned will probably transport turntable seperately so thats 15kg saved too I guess. Anyone got any tips on £500 of midtops?
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slaz
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Posted: 25 March 2021 at 6:48pm |
OK you're thinking along the right lines in many ways but ... Studio is really talking about LiFePo4 .... which is a derivative/evolution from Li-ON. 4S LiFePo4 is a better voltage than 3S Li-on or Li-Po. Very nice, and could save you a good deal of weight, but can also put a sizeable hole in your budget. 100Ah LiFePo4 is ... ~ not much change from £500. Another couple of comments :- The 12NDL76 is not really a "sub" driver - but may very well do a good job to 60Hz or so. The inverter is not really a good idea - will cost plenty of precious Ah from your battery. Laptop - if it uses 19V (like most) - you can get a car laptop charger (with cigar-lighter plug) that'll give you 19V at up to 4A or so. Definitely more power-efficient. Best to use a laptop with small-ish screen and SSD drive. Mixer ? Do you really need one ? Surely DJ-ing s/w on the laptop can do cross-fading and F/X etc. If its mic action you want - look at a Berry USB302 - works v. nicely and runs all day from a USB power bank, and has a good mic input (but only one). Turntable ? Really ? For a bike system ? Well if you must - a RIAA input is one reason for having a mixer I guess .... but look out for small mixers which can run directly from 12V DC or so - they do exist. Surely a turntable will mean you'll also need a fold-up picnic table or some such - and a way of levelling it - more stuff to carry. Oh yeah, you can get battery-powered RIAA pre-amps ... not top quality - you probably wouldn't want it with an expensive hi-fi, and needs a PP3 battery and needs to be opened up to change the battery. Got one here that I never use. DSP - well maybe you already have a DSP (I assue you mean something like a DCX2496 ? ). Look at the Thomann mini-DSP - runs on low-voltage DC like 12V - but needs your laptop to configure it.
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REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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imageoven
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Posted: 25 March 2021 at 7:50pm |
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There are 12v native (or dual supply) turntables available. I use a Vestax handytrax on one of my portable setups, which is a bit cheap and cheerfull, but is nice and light and outputs line level too. Theres also things like the technics SL-7... lost my pair of friscodisco's in a fire sadly... |
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Keep pushing on, things are gonna get better.
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infrasound
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Joined: 13 May 2011 Location: Brizzle Status: Offline Points: 2276 |
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Posted: 25 March 2021 at 7:57pm |
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Take a read of https://forum.speakerplans.com/lockdown-audio-a-12v-3way-small-rig-build_topic105202_page1.html
.. A large proportion of which is me banging on about horn extensions, which I'll still recommend! Lots more of the low stuff
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studio45
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Posted: 26 March 2021 at 4:30pm |
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Yes defo go for lithium iron phosphate cells not lithium ion, you can't make a "12v" nominal battery from Li-Ion - you either get 11.1v with 3 cells or 14.4v with 4 cells. The one is too low, you won;t be able to fully discharge it before you hit the low voltage cutoff point on the amp. The other is too high, when fully charged the amp won't start up (or could blow a fuse) Whereas four LiFePO4 cells in series gives you 12.8v nominal, that will run the amp just fine.
It took a bit of looking but this is the kind of product I mean from Aliexpress: There are a lot of other more expensive listings for 8 or more cells, you only need four, unless of course you want to have a spare battery. You will also need a LiFePO4 BMS board to protect these cells, they are available on eBay - a 50 or 75 amp model would do you fine although 100 amp models might be easier to find. These cells are rated (apparently, take such things written on ALiexpress with a pinch of salt) for 3C discharge so that would put the absolute limit at 270 amps. You will also want a fuse right on the pack in the positive line for safety - the rating should be the same as your BMS.
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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CFLsound
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Posted: 26 March 2021 at 7:39pm |
Nice one! Didnt see this post but this is all super valuable, love the rig, gunna have a big read through soon, sound like our goals are pretty similar to what yours were. I may send some questions your way soon
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CFLsound
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Posted: 26 March 2021 at 7:46pm |
Cool thanks for that, so many different options on aliexpress but that clarifies things. I'm gunna have a read up about Li Ion and will go from there, will probabaly have some questions about them but thanks for the tips, big weight saver!
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Jack1991
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Posted: 27 March 2021 at 10:21pm |
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This is sounding like a decent plan! Some of what i am about to write has already been said, but just adding to it too. I used my 12v system in a portable version on a cart with just one tham12 and i also used 1x turbosound ip82 for the mid tops when in the 'portable mode'. I rekon 1x turbosound ip82 could easily keep up with 2x tham12s, although i havent tried it myself so could be wrong but i dont think youd need 2x turbosounds, so could save a bit of weight here. Also i weighed each tham12 (with the driver fitted) and it came back at 22kg, per tham12. Im using Thomman 12-280-W drivers. They are cheap and seem decent & although i have nothing to compare them to im impressed. Also their rms power rating are more than i need to put through them. Just a suggestion but instead of a mixer and a turntable, you could use a dj controller. I have a Pioneer ddj 400 which just runs off the usb from the laptop, it also has a mic input too on it. Also pretty cheap 2nd hand, and small and portable. For the latop charger i have recently found out majority if not all are 19v dc. So looking into making a charger cable up with a 12v dc to 19v dc step up converter in to run straight from the 12v battery. DSP (ive just bought one myself but not arrived yet) read loads of good reviews from people, the Thomann 4x4 mini dsp. Runs straight from 12v dc too. Battery wise im using a 110ah agm Leoch leisure battery. Its 24kg and when using my full system at the time of 2x tham 12s and custom mids & tops. I played it at max volume for around 6/7 hours and the battery dropped about 20/25%. So lasted alot longer than i expected. Hope this helps 🙂👍🏼
Edited by Jack1991 - 28 March 2021 at 8:23am |
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CFLsound
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Posted: 28 March 2021 at 11:10pm |
Jack1991 your rig is pretty much exactly what we had in mind, looks great. I think we're going to go with a dj controller and a turntable just because it's nice to have the option. Also me and some friends record a lot to cassettes so that will probably crop up somewhere along the line too. those tham drivers were our second choice, seems to be they're a pretty popular option so maybe we'll reconsider and save the cash. I mentioned in your thread that if you wanted a place to test the rig out for the day in Bristol I could sort something out. Would be cool to hear what it can do.
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CFLsound wrote: