High Power design

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dunderchief

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Joined 2003
#1
I've been putting together my install for about 6 months now and the last thing I've come down to is amps. I'm wondering if there is a know design that could deliver perhaps between 400 and 500 watts per channel with a power supply built for mobile use. Would anybody be interested in designing one. I would also be interested in a design in the 1kW+ range. Of course I'm not looking for Class A or probably anything close, but I would like something that could compete with the likes of Brax and Sinfoni. Any help would be greatly appreciated.
 
#2
You can have a tube buffered gainclone that delivers 50W per mosfet. If you put 3 mosfets per channel, that is 150W per channel. For 500W, you need 10 mosfets. But you don't need that much power anyway, unless you plan on wearing earplugs while listening. Instead of raw power, use horn and other efficient speakers. Active all speakers, you can have more power than you need. And yes: both tube (maybe 6GM8) and the mosfets used in gainclone can run on 12V, with no step-up. I would not be surpriced that it will be better than a C7T. And the schematic is within the gainclone folder.
 
#4
I don't have the information in front of me here. But they should be available with a google search. If you look at the spec sheet of LM3875 from National, it should say that it can operates with +12V. Now, you may wish to use a voltage inverter and creates a -12V too.

Same with the 6GM8. I am very sure that there are commercial products that runs this tube with only 12V.

In short, a tubed gainclone can be run using car battery with limited work on the power supply.
 
#5
With +-12V voltage rails you probably can expect something like 9W/8Ohms, 18W/4Ohms and 36W into 2Ohms.
And please note these are overoptimistic values.
See here here for results with the LM3875 for example.
They are nuch less than the figures I´ve given.
You definitely need more voltage swing to achieve those power levels and so build a SMPS which will probably be the hardest part of the amp to build.

You´ll find one design here.

A nice and compact power amp to go with it could be this one. (ZapPulse)

Cheers
Jens

Jens - thinks the car audio people should buy speakers with higher efficiency....
 
#8
For the subwoofer, I will do the PWM thing (ZapPulse). For the 2 tweeters and 2 woofers (assuming we have 5 speakers in the system), I will use something similiar to what Joe has done.
Click to expand...
Could be anice solution but you´d still need the SMPS to get higher rail voltage at least for the ZapPulse.
Regarding the tube buffer you´d need even more voltage.:bigeyes:

Cheers
Jens
 
#9
Joe's schematic is not going to work as it. I will probably use 6GM8 instead of 6992 and give both the 6GM8 and LM3886 +/- 12V. Some of the resistor value within the schematic will need to be changed as well. I will not use ZapPulse, but build a PWM amplifier utilizing TI chip set.

All I am saying is that a tube bufferd gainclone should be explored as car amplifier. However, some work remains.
 
#11
A little excessive to put tubes in a car, perhaps yes, a waste, perhaps not. Why not make my car a nice place to listen to music too. I like both the GC and the tube buffered idea, but my worry still lies in the SMPS. Does anybody have any experience building one, especially one with large capabilities (i.e. 1kW). I realize that the ideal solution would be to use more efficient drivers, but unfortunately I'm sponsered so I must use the drivers given to me. They do stand generally around 93 db/w/m but in competition more power means more points usually, so I'm generally forced to go the high power route.
 
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