Class D digital PWM power amplifiers on the playa

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Class D digital PWM power amplifiers on the playa

Postby kstlfido » Mon Jul 30, 2012 11:24 pm

Hi folks-

I help run camp Bioluminati / Pimp Yr Bike. As usual, we provide music for the pimping area. No dance club levels, ~70 to 100 watts per channel amps have suited us fine. We've been using old receivers and what not that eventually die. I'd like to try something more robust. I'd like to try a decent Class D amp. There are a fair number of assembled boards out there (my preference as I would like to keep it under $100). Complete amps plug-n-play too, if not too pricey...

How do they hold up to the heat? Robust? Any problems? Anyone had experience with some of the popular brands- Shure Electronics? 41Hz? L20D? HiFimeDIY?

One day I will build a tube amp to match the speakers. But for now a chip amp will do fine. Pic of the speakers I built for our camp below. This will be their 4th year.

Thanks- Kent

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Re: Class D digital PWM power amplifiers on the playa

Postby MikeGyver » Mon Jul 30, 2012 11:34 pm

Cant help with the Amp, But I Love the speakers, the surveyor stands fit great. I never would have thought of those for outdoor speaker stands.
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Re: Class D digital PWM power amplifiers on the playa

Postby some seeing eye » Tue Jul 31, 2012 5:44 am

The most ideal solution is to enclose the power supplies and amps in an entirely sealed dustproof chassis. That may require beefing up the heat sinks and getting them on the outside of the box if there is a way to keep the MOSFETs inside the box. Ditto the power supply. It would be a good idea to ask someone on a forum how hot the inductor and RC network on the output filter get at full power. If there is heat there, no idea how you would get rid of it in a sealed box. A D is going to produce less heat by principle than an A, B, AB, etc. So that is good.

Same with the power supply, what gets hot when the amp is running at full power?

It would be cool to run some kind of air to air or air to water heat exchanger for fun. Of course dust could corrode. Aluminum NEMA waterproof enclosures would be dustproof. The RF ones are steampunk. Surplus or catalog items. See pic.

Or since they are cheap, you could let them get dusty, try to wash them after, first with a light acid, then water. If there are protection relays, those may not wash.

Generator power is extremely crappy. Running off a battery would be ideal, even if through an inverter. If running off a generator, no idea how hardened the power supplies are against spikes. People run commercial class D's off generators all the time though.

Obviously keep the amp in the shade.

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Re: Class D digital PWM power amplifiers on the playa

Postby kstlfido » Wed Aug 01, 2012 12:52 am

Thanks, some seeing eye, for the tips. The open air solution is super easy- I might end up trying that. I've looked at the pics of the boards- one relocate the MOSFETS under the board and mount them directly to a case. I could add a sink to the case to increase cooling.

I'm going to poke over at diyaudio and see if there are any threads relating to this issue.

Cheers- Kent
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Re: Class D digital PWM power amplifiers on the playa

Postby CrispyDave » Wed Aug 01, 2012 8:27 pm

Try a larger cooler with good insulation properties, fit the amp/s inside a cooler/s and seal them shut run copper wire coils inside the cooler and have it enter at one end and exit at the other, seal these egresss as well. Run chilled water or freon or air through the could, ideally you have a third cooler to run both coils through and just pump air through the coils and have them deliver cold air via the coils in the coolers to the amps....
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Re: Class D digital PWM power amplifiers on the playa

Postby CrispyDave » Wed Aug 01, 2012 8:33 pm

2000 Watt Mono Block Waterproof Marine Mosfet Digital Amplifiers work great.

Load them down into a cooler and go to town....
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Re: Class D digital PWM power amplifiers on the playa

Postby Elorrum » Wed Aug 01, 2012 8:47 pm

I've used smaller t-amps with the tripath chips. I've built them in small cookie tins in an insulated lunch bag, and run them with a 12V SLA, or just 8 AA batteries. Last year I brought a cheap lepai with subwoofer output. CHEAP but good near field, and okay volume for a small group. This year, hopefully I'm bringing a Shure 100Watt board, (which is going to generate some more heat) and some vinyl fence post line arrays. To be honest, I never get to the craftsman part of these projects the first year I attempt them, and just put the gear in the insulated lunch bag... so I'm not an authority on this. I think an aluminum project box would dissipate some of the heat, but a bigger cookie tin and a larger clean insulated grocery bag for this year perhaps.

BTW that's an absolutely beautiful set of speakers and stands and tube amps there. holy moly!
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Re: Class D digital PWM power amplifiers on the playa

Postby nixiebunny » Fri Aug 03, 2012 1:00 pm

I put a Pioneer Class D car stereo amplifier on my bike for this year. I've been using it since last October around town, and it works quite well. The unit I got is a Pioneer GM-D9500F, 150W x 2 into 8 ohms in stereo mode.

You might want to check out the system...
http://www.cathodecorner.com/loudbike/
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