Class-D, New revision, New PCBs

Time to do an updated version of my class-d amplifier. Last revision was more of a prototype, with a mother board where all the switching and output filter was placed, and a daughter board where the modulator was placed. This allowed for playing a lot with the modulator, but now it is time to integrate

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Class-d Amp listening impressions

Have now tuned the stereo version somewhat.

It’s running 300 kHz, and is able to put out some 150 W in 8 ohm, though I have not tried yet to test it to the limit.

It is build into an old Yamaha box, using a 3 x 35V transformer of a decent size and

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Class-d soon in stereo!!

Have had some time to finish a main board more, so soon I’ll have the oppotunity to try the amp out on my stereo set-up.

So soon the truth will come out ….. does this designhave any potential as a full rage amlifier?

I have done some modifications as well. Main point being that I

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UcD Modulator

Got the UcD modulator daughter board assembled. It’s the UcD on the right with the DIP comparator. It works quite well and played the first time, something I have found with UcD all the times I have tried this kind of modulator .. it’s just so easy to get to oscillate.

With the chosen components

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New Modulator PCB

New vs. old PCB

Been too long since I posted anything here. Have been bussy …. but not with DIY Anyway a bit of DIY have been done I made a new and improved PCB for the SODA modulator. Now both the opamp and the compaator is SMD, as I’ve settled for MAX913. Though

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Class-d …. it’s alive

Class-d amp running

The design is a self oscillating amp (SODA … read more here, use Google to reanslate from German), and it simply didn’t want to start oscillating.

Just running the modulator without inclusion of the MosFet output stage, it worked like a charm, but including the output stage just

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Class-d Motherboard and modulators

Class-d Motherboard

As you have probably seen on my web site, I have been working on class-d amplifiers for some time.

I have succesfully made a 400W full bridge for a subwofer, and a small mini amp based on the UcD design presented by Bruno Putzeys.

I have also for some time been working

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Using DirectFET from IRF for DIY amplifiers

The new series of FETs from International Rectifier called DirectFet, are not really DIY friendly

Look at the comparison between a normal TO-220 stle of MosFet, here IRF640 that I have used in my 400W amp. Besides is the tiny IRF6785 DirectFET which should we good for the same kind of amp size!!!


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