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tfboy 7th February 2008 02:17 PM

Which 12V DC SMPS for amps?
Hi there. Long time reader, first time poster, so please be gentle with me!

I'm working on a new build for my car. I currently have a few car audio amps driving the equipment, however, I think I need a change!

The reason I'm changing all this is because I'm planning on driving my speakers actively, ditching the crossovers they came with; I'll be using something like a Pioneer DEX-P9 and DEQ-P9 to do all the filtering and crossovers. I just don't have enough space in the car boot to put normal car audio amps and so I'm looking at going down the Class D route to save space yet get decent quality power.

My current thought it to have the following:
  • 2x Hypex UcD180 for each main woofer driver
  • 2x Hypex UcD180 for each tweeter
  • 1x Hypex UcD400 to drive a subwoofer.
I sent an email off to Hypex asking about PSU possibilities because obviously being used in a vehicle, I only have a 12 - 14.4V DC supply and no 230V AC.

They recommended I have a look at coldamp's CPS80 and I think I would possibly need two of those units to comfortably drive the above UcD amps. Although getting two ends up being rather pricey :(

Can you advise what you think on the above? Are there 12VDC - +-40V DC ready-built kits other than the CPS80 available? Ideally, if there was something with more power, then I could have just one. Or is one CPS80 enough for the above? I'm an electronics engineer and pretty handy with soldering and all that, but my electronic design skills are abandoning me so I can't see myself building something from scratch and making up my own windings for transformers, etc.

Recommendations gratefully received :)

P.S I posted this in the Class D section and not the car audio as I thought it pertained more to class D and powering it than car audio specifically. Please move if you think it would be better in the other section :)

wapajk 7th February 2008 06:35 PM

you could try Rod Eliot design, he alo provide great deal of info. It is DIY.

With little modifications(using larger core,adding more mosfets in parallel, and increasing turn ratio) it can deliver much more power, and higher voltages.

Just a thought!!

tfboy 8th February 2008 01:03 AM

Hi Wapajk.

Thanks for the link. I did come across it doing some reading, but it sounds a bit too involved for me right now, plus I'd have to work out things and that could be dangerous :p

y8s 8th February 2008 02:26 AM

I just read the ESP page today. it doesn't look too complex, just the transformer may be a challenge. might not be a bad project if you have a current limited way to test it first.

MikeHunt79 8th February 2008 03:03 AM

take a look at the thread in this section called "Big-t" :)

luka 8th February 2008 08:19 AM


Winding toroids is not that hard, you only have to spread all and each winding around core, not just say one primary on 1/2 of core and other on other 1/2, both must be on all... same for all others

+ if you would go under Car Audio -> Favorite Threads and Posts in "Car Audio", where this thread should be, you would find one allready made design. I made few of them last one yesterday and I got 280w like nobody's business... now I will add snubbers just to get rid of that small 2.8Mhz ringing that is present

tfboy 8th February 2008 02:11 PM

Thanks for the encouragement, chaps :)

The only major issue I see is that I'd be looking for around 800W to 1kW available to the amps, and I admit that's quite a lot to have for a home-built design. Of course, I could build multiple power supplies to spread the load, but then I'm probably going to have the space limitations hit me once more.

Unless there's an easy design that can provide similar power to the CPS80 from coldamp, I might as well go with Coldamp's design. Sure, it's expensive, but it's a tried and tested solution :)

kck87 10th February 2008 11:16 AM

original schema

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TheMG 10th February 2008 04:00 PM


Originally posted by tfboy
The only major issue I see is that I'd be looking for around 800W to 1kW available to the amps, and I admit that's quite a lot to have for a home-built design.
Even though all those UCDs are totaling a max output power of 760W RMS, which after the 90% efficiency is factored in is ~844W power drawn, you will most likely never actually be pumping out that much power. Unless you're planning on going crazy with pumping pure sines through your speakers at full volume, you're not going to need that much power.

Plus, you'd have to be running the modules at their full +/- 65V for the UCD400 and +/- 45V for the UCD180, which are the voltages Hypex used to obtain their output power ratings. Which brings me to another point, you'll want to have two power supplies if you wish to get the most out of the modules, for the reason stated above (diff voltages).

jackinnj 10th February 2008 06:06 PM

Why not just get the appropriate chip from Texas Instruments? they have the H-Bridge "in situ" so you don't have to waste time building a switch mode power supply.

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