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From: Vladimir Vassilevsky on 7 Nov 2008 15:23


mrdarrett(a)gmail.com wrote:

> On Nov 7, 6:34 am, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> wrote:
>
>>mrdarr...(a)gmail.com wrote:
>>
>>>Any competitors to this product:
>>>http://www.irf.com/product-info/datasheets/data/irs2092.pdf
>>
>>There used to be the analog class D ICs from Zetex and few other
>>vendors, however it seems like everybody went digital.
>>
>>
>>>Any comments on the above?
>>
>>0. It works.
>>1. It is specifically made to force you to use DirectFETs.
>>2. It is quite tricky to make it work as good as advertized, however it
>>is possible.
>>
>
> DirectFETs, eh? So no IRF530s, even if paralleled?

Possible. However the THD and the power efficiency will suffer
significantly (compared to the DirectFETs).


> I don't suppose it's possible to use something like this to drive
> external mosfets (instead of speakers directly)...?
> http://www.ti.com/lit/gpn/tpa3123d2

This one is closer to the boom-box class, whereas IRS2092 pretends to be
high fidelity. What are you trying to build?


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
From: mrdarrett on 7 Nov 2008 15:32
On Nov 7, 12:23 pm, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
wrote:
> mrdarr...(a)gmail.com wrote:
> > On Nov 7, 6:34 am, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> > wrote:
>
> >>mrdarr...(a)gmail.com wrote:
>
> >>>Any competitors to this product:
> >>>http://www.irf.com/product-info/datasheets/data/irs2092.pdf
>
> >>There used to be the analog class D ICs from Zetex and few other
> >>vendors, however it seems like everybody went digital.
>
> >>>Any comments on the above?
>
> >>0. It works.
> >>1. It is specifically made to force you to use DirectFETs.
> >>2. It is quite tricky to make it work as good as advertized, however it
> >>is possible.
>
> > DirectFETs, eh? So no IRF530s, even if paralleled?
>
> Possible. However the THD and the power efficiency will suffer
> significantly (compared to the DirectFETs).
>
> > I don't suppose it's possible to use something like this to drive
> > external mosfets (instead of speakers directly)...?
> >http://www.ti.com/lit/gpn/tpa3123d2
>
> This one is closer to the boom-box class, whereas IRS2092 pretends to be
> high fidelity. What are you trying to build?


60Wpc audio amplifier for home party use, maybe adapt it to a homemade
car stereo amplifier once I get a good-enough boost converter built.

Class D would allow me to use a smaller (cheaper) transformer... just
so long as it sounds reasonable: <1% THD+N...

Thanks,

Michael
From: Eeyore on 8 Nov 2008 05:31


mrdarrett(a)gmail.com wrote:

> On Nov 7, 12:23 pm, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> wrote:
> > mrdarr...(a)gmail.com wrote:
> > > On Nov 7, 6:34 am, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> > > wrote:
> >
> > >>mrdarr...(a)gmail.com wrote:
> >
> > >>>Any competitors to this product:
> > >>>http://www.irf.com/product-info/datasheets/data/irs2092.pdf
> >
> > >>There used to be the analog class D ICs from Zetex and few other
> > >>vendors, however it seems like everybody went digital.
> >
> > >>>Any comments on the above?
> >
> > >>0. It works.
> > >>1. It is specifically made to force you to use DirectFETs.
> > >>2. It is quite tricky to make it work as good as advertized, however it
> > >>is possible.
> >
> > > DirectFETs, eh? So no IRF530s, even if paralleled?
> >
> > Possible. However the THD and the power efficiency will suffer
> > significantly (compared to the DirectFETs).
> >
> > > I don't suppose it's possible to use something like this to drive
> > > external mosfets (instead of speakers directly)...?
> > >http://www.ti.com/lit/gpn/tpa3123d2
> >
> > This one is closer to the boom-box class, whereas IRS2092 pretends to be
> > high fidelity. What are you trying to build?
>
> 60Wpc audio amplifier for home party use, maybe adapt it to a homemade
> car stereo amplifier once I get a good-enough boost converter built.
>
> Class D would allow me to use a smaller (cheaper) transformer... just
> so long as it sounds reasonable: <1% THD+N...

THD+N alone tells you quite little about the sound. The harmonic content
distribution is vastly more important.

Typical solid state amps with 1% THD sound disgusting. You only need a tiny
transformer by my standards (I've done up to 2kW for professional SR use),
build a gainclone (google it). You may want a slightly larger transformer (abd
heatsink) for 'party' use since the continuous power demand will be a LOT
greater than normal hi-fi use.

Graham

From: mrdarrett on 8 Nov 2008 12:22
On Nov 8, 2:31 am, Eeyore <rabbitsfriendsandrelati...(a)hotmail.com>
wrote:
> mrdarr...(a)gmail.com wrote:
> > On Nov 7, 12:23 pm, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> > wrote:
> > > mrdarr...(a)gmail.com wrote:
> > > > On Nov 7, 6:34 am, Vladimir Vassilevsky <antispam_bo...(a)hotmail.com>
> > > > wrote:
>
> > > >>mrdarr...(a)gmail.com wrote:
>
> > > >>>Any competitors to this product:
> > > >>>http://www.irf.com/product-info/datasheets/data/irs2092.pdf
>
> > > >>There used to be the analog class D ICs from Zetex and few other
> > > >>vendors, however it seems like everybody went digital.
>
> > > >>>Any comments on the above?
>
> > > >>0. It works.
> > > >>1. It is specifically made to force you to use DirectFETs.
> > > >>2. It is quite tricky to make it work as good as advertized, however it
> > > >>is possible.
>
> > > > DirectFETs, eh? So no IRF530s, even if paralleled?
>
> > > Possible. However the THD and the power efficiency will suffer
> > > significantly (compared to the DirectFETs).
>
> > > > I don't suppose it's possible to use something like this to drive
> > > > external mosfets (instead of speakers directly)...?
> > > >http://www.ti.com/lit/gpn/tpa3123d2
>
> > > This one is closer to the boom-box class, whereas IRS2092 pretends to be
> > > high fidelity. What are you trying to build?
>
> > 60Wpc audio amplifier for home party use, maybe adapt it to a homemade
> > car stereo amplifier once I get a good-enough boost converter built.
>
> > Class D would allow me to use a smaller (cheaper) transformer... just
> > so long as it sounds reasonable: <1% THD+N...
>
> THD+N alone tells you quite little about the sound. The harmonic content
> distribution is vastly more important.
>
> Typical solid state amps with 1% THD sound disgusting. You only need a tiny
> transformer by my standards (I've done up to 2kW for professional SR use),
> build a gainclone (google it).


What's the fun in that?

Besides, from experience (party at my in-laws' house) chipamps burn
out easily from too much partying, and they're expensive to replace.
Brother-in-law's JVC unit had an STK 412-090 "chip amp" - both
channels on one chip, IIRC. That one blew out one night. Heat
transfer isn't all that great either. With individual transistors you
have a better chance at cooling... plus if they blow out, they're
cheap to replace.

I was going to build this (second schematic):
http://sound.westhost.com/project03.htm

Cheapish output transistors (cheaper than the 3A project transistors),
and reasonable THD.

Then I thought, why not go Class D... smaller transformer...


> You may want a slightly larger transformer (abd
> heatsink) for 'party' use since the continuous power demand will be a LOT
> greater than normal hi-fi use.


Yep, just so long as the transformer can handle full continuous power
+ heat generation for all channels...

> Graham

Michael
From: Eeyore on 8 Nov 2008 12:39


mrdarrett(a)gmail.com wrote:

> Eeyore wrote:
> >
> > THD+N alone tells you quite little about the sound. The harmonic content
> > distribution is vastly more important.
> >
> > Typical solid state amps with 1% THD sound disgusting. You only need a tiny
> > transformer by my standards (I've done up to 2kW for professional SR use),
> > build a gainclone (google it).
>
> What's the fun in that?
>
> Besides, from experience (party at my in-laws' house) chipamps burn
> out easily from too much partying, and they're expensive to replace.
> Brother-in-law's JVC unit had an STK 412-090 "chip amp" - both
> channels on one chip, IIRC. That one blew out one night. Heat
> transfer isn't all that great either.

Why do you think I said it needed a good heatsink ?

I 'torture' my designs into 4 and 2 ohms loads with ultra-compressed low dynamic
range 'DJ@ music. Why ? Because we know people do that. Ditto for speakers.

You're talking to an expert in the field of audio amplication and reproduction. DO
NOT try and make out you're cleverer.

If you want to make a piece of junk, fine but don't bother listening to me will
you.

You need to learn about output stage efficiency, Rthetaj-c, Rthetaj-a and
Rthetac-a. Motorola used to have some ANCIENT app notes on it. It's kinda assumed
these days that DESIGNERS (and this is a design group) might understand these
thing.

You also need to know about Iav vs Irms in the power supply, ripple current, ripple
voltage etc etc.

It's not FUN (esp getting it wrong) it's WORK ! And I see no sign of you having any
aptitiude for learning.

Graham

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