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Class D amp + Active Crossover Advice |
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shakti 
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Joined: 05 April 2014 Status: Offline Points: 3 |
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 Topic: Class D amp + Active Crossover AdvicePosted: 05 April 2014 at 3:23pm |
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Hiya,
I've been researching for a little while about 12v systems but am still a total newbie so go easy on me  I am hoping to build a 12v system with a 12" speaker (400w or 500w), 2x 6" speakers (200w each) for mids and a piezo horn tweeter or array on top. (mainly playing a reggae/dub sound) I've been looking into getting the 3000w The Loudest Class D car amp (http://www.theloudest.co.uk/?sectionid=2&page=view_product&product_id=102). I originally had my eye on the 5 channel 3000w amp from them but it is Class AB and have seen a lot of people saying that this will drain the power much faster than Class D. Into this I would have a 3 way active crossover (something like this? http://www.ebay.co.uk/itm/Lanzar-OPTI-3-Three-Way-Car-Audio-Amplifier-Amp-Active-Splitter-Crossover-/351029145247?pt=UK_In_Car_Technology&hash=item51baf7ae9f) But I am thinking about how much power that is also going to use.... so power saving wise would I be better off having a Class AB amp with multiple channels and no active crossover or a Class D amp with a three way active crossover? Does anyone recommend any other amps/active crossovers than the links I have posted? Do I need a 3000w amp? Have I got it totally wrong? Any advice will be much appreciated!!  Edited by shakti - 05 April 2014 at 3:30pm |
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patryk1305
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Joined: 13 December 2012 Location: United Kingdom Status: Offline Points: 488 |
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Posted: 05 April 2014 at 3:38pm |
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Class D is more efficient than Class AB so you are better off with a class D amp.
Either way you will need an active crossover anyway to adjust the system to your requirement. (You could use passive if you are on a budget) How much power you will need will depend on how loud you need it but also the speakers you use. What speakers do you have in mind? (specific manufacturer and model)
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lutkeveld
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Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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Posted: 05 April 2014 at 3:40pm |
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Class D is about 4 times more efficient than AB with music signal. My advice would be, don't get an amp with more than 50 watts. TK2050, or Tripath TAA4100A or TA2020 based amplifier. Look into building a boominator, lot's of fun and relatively easy to build. Plans are on Diyaudio.com class-d section.
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shakti
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Posted: 05 April 2014 at 3:56pm |
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Speaker wise an Eminence Delta 12" 500w 8ohm and then two Eminence Alpha 6" 100w 4ohm, piezos I am not sure on yet and I am still keeping my eyes very much open for other speakers... though the Eminence ones are my current favourites in regards to quality and budget. Any recommendations much appreciated.
I think I will go with the Class D amp for efficiency purposes. In regards to 50w amp would it be better to get multiple 50w amps to power individual speaker (as just the one is is going to limit noise level capability?) or just stick with going for the bigger wattage amp. Have seen the Boominator, had a look at the plans a while ago and looks like a great little system and will probably give one a go, however it seems it would serve a different purpose than to the one I have in mind (a portable traditional reggae style system, I guess I could modify it to my own wants/needs) Edited by shakti - 05 April 2014 at 4:05pm |
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lutkeveld
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Joined: 23 September 2013 Location: The Netherlands Status: Offline Points: 517 |
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Posted: 05 April 2014 at 4:24pm |
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For outdoor use the Boominator will blow anything of its size away. If you want to try something yourself and go trial and error that's fine ofcourse. If you want performance, I'd recommend the Boominator.
Edited by lutkeveld - 05 April 2014 at 4:24pm |
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studio45
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Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864 |
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Posted: 05 April 2014 at 5:12pm |
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For efficiency, nothing really beats horns.
A couple of years ago I built a lashed-together 12v rig on a sack-barrow out of a 12" tapped horn, a Toa factory announcement ("tannoy") re-entrant horn and a curved bank of 10 Motorola piezos all cable-tied together, driven from a class AB car amp that was about 250w into 8 ohms per channel and had a built-in crossover to split the tapped horn from the mid/high array at 300Hz. I made a passive filter board for the mid-high section, consisting of a broad notch or mid-cut filter for the Toa horn to get its response somewhat flatter from 300 to (maybe) 4k, and some resistors across and in series with the piezos to get them sounding a bit more musical. I also damped the outside and bell of the horn with some bituminous damping sheet and stuffed some fibreglass insulation down the throat. It played extremely loudly and had a most pleasing "soundsystem" quality, and lasted about 4 hours on a 38Ah Yuasa battery.
These days for the bike trailer PA rigs I am using TI PurePath based amps (from Sure Electronics) which can match the output of that car amp, but last 8 hours on the same battery, the same tapped horn bass bin, and I've been able to get some Tannoy V8 coaxial PA tops. They cross over at 100Hz. However, they're very much a PA box, and don't look nearly as good as an array of horns and tweeters, nor will they clatter and bang in a soundsystem-like manner if you want them to. A full-range 12" like the Fane Sovereign 12-300LT would perform a similar function, and look much more the part. So my suggestion would be to build a 1x12" tapped horn for 50-100Hz, then a mid-hi box with 1x12" wizzer-cone mid-hi 100Hz-out, 10xpiezo curved array 6kHz-out. Drive it with 2x Sure "2x300W" TAS5630 board, powered by 1x Sure 500W boost converter at36v (total power draw will probably not exceed 500W as the "300W" board only does 100 a side into 8 at 36v, so between the bass bin, mid and piezos you'll probably be just over 300W, and if you get a 4 ohm bass driver you'll be on about 450W peak). Obviously this leaves you with a spare channel for future experimentation or expansion. Total cost of the three Sure boards inc delivery from China will be about £114, for which you'll be hard pressed to get a decent class D car amp with four outputs. For crossover purposes I use 2-way filter boards (one 24dB/oct highpass and lowpass on each board) from the American company Xkitz, which I populated myself but in retrospect I would have ordered them ready-built as it was quite time-consuming and did not work out any cheaper. They will be much more power-efficient than the Lanzar unit; the thing is full of very bright LED's for a start! I did have to upgrade the Xkitz power regulator to a 1 amp type from 500mA and use a single reg. for two boards to stop an oscillation issue though, which was mildly taxing. You may not encounter the problem, I never did get to the bottom of it. So basically car audio gear is fine for starting out, but when you want to step up a level the products are all out there and really not that expensive...might as well start a couple of rungs up the tech ladder ;)
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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amlu
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Joined: 30 November 2009 Location: london Status: Offline Points: 740 |
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Posted: 06 April 2014 at 2:25am |
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have a look on "active crossover" and "electronic crossover" on ebay, with filter for used gear.
you can find some nice vintage car audio. managed to pick up my 3 way kenwood crossover with variable crossover points, plus a kicker sub crossover, all for cheap. they coming and going keep an eye on it. stay away from car audio ampliffiers, theres plenty of power available in a car, but a limited amount on battery powered sounsystem.... pure class d board do better. hifimediy, sure hifi, 41hz...have a look. when looking for speakers note the efificiency parameter... the more db per watt of power the better for us. much more expensive too... quality costs looks like. |
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bitSmasher
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Joined: 23 June 2012 Location: Melbourne Status: Offline Points: 2295 |
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Posted: 07 April 2014 at 6:04am |
I have a few of these, planning to build Cubo12 with them. Previously made a couple of JBell SS15 that were slightly altered specificially for low powered usage with the 12LFA - they worked great but were a bit too big for portable sound Anyway, worth discussing what you plan for sub - hopefully I can start the Cubo soon (been saying that for months!) and can give some feedback on its performance |
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shakti wrote: