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Date: Fri, 25 Jan 2002 12:29:51 -0500
To: rsgb_lf_group@blacksheep.org
From: "Steve Dove" <dsp@hifidelity.com>
Subject: Re: LF: Class D TX chips
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Hi Zim,

To be fair to TI, their intention is that these amplifiers be used in self-powered
speakers, where the speaker wire length is inches (sorry, cems) at worst.
For the last few weeks I've had a couple of these driving a pair of whacking 
great JBLs in my office, and they sound better than they have any right to.
Big welly from something about the same size as an op-amp.  Amazing.
Better yet, they've passed the headache test (long-term listening fatigue)
which many amplifiers haven't.

We're designing them into a product for someone now, which incidentally
  -  and highly relevant to your point  -  like any other commercial product 
is going to have to pass Part 15 and CE emissions testing . . .  
Anyway; I'll drag one outside and plonk it under the antenna and see what
happens.
 
Your local friendly LF pollutant,

        Steve        W3EEE


1/26/2002 8:46:32 AM, "Graeme Zimmer" <gzimmer@optushome.com.au> wrote:

>Hi,
>
>Those of you interested in digital transmitters might take a look at the
>new(ish) TPA3000D1 from TI.
>
>www.ti.com/sc/tpa3000d1
>
>It's a class D audio amp capable of 17 Watts audio. It has a switching speed
>around 200 Khz.
>
>I figure it's a "good news" and "bad news" story.
>
>The good news is that it could possibly be used as a basis for a simple qrp
>VLF TX
>(I figure that the RC osc could be over-driven by an Xtal osc...)
>
>The bad news is that they are seriously proposing that these things be used
>in consumer equipment without any form of output filter....
>
>......................... Zim
>
>
>