Page 6 of 8

Posted: Mon Feb 26, 2007 7:29 pm
by eezip
It's hard to tell from those pics. The large DIP IC looks like a HIP4080 because of the high pin count and it looks like an Intersil logo on top. Although it allows you to design a highly integrated full bridge amp, it has an internal charge pump which operates at 10kHz and it takes heroic measures to produce good audio performance using this IC. The 4080 was designed for motor control where an integrated charge pump is a huge advantage doesn't bother the circuit operation.

It's really too hard to tell much other than the output filter appears to use stacked cores [not a good idea IMO] and quality film filter caps [good]. There's a fair amount of secondary capacitance by the amplifier output stage but the gate driver isn't terribly close to the amp output devices. Other than that, it would be almost purely speculation. Sorry, there's only so much to gather from a tiny picture.

Posted: Mon Feb 26, 2007 8:03 pm
by John
The site is nice for a quick reference and browse, but it to me seems somewhat pointless that it does have a ton of really high definition and close up pictures of the amps featured.

Posted: Mon Feb 26, 2007 11:50 pm
by eezip
John wrote:that it does have a ton of...pictures


You mean doesn't have a ton of pics? Yeah, that's a bummer

Posted: Tue Feb 27, 2007 12:00 pm
by bassman07
if it has like 4 guage wire on the inside its carrying some current lol! i always liked looking at the inside of us amps guts!

Posted: Tue Feb 27, 2007 12:12 pm
by John
bassman07 wrote:if it has like 4 guage wire on the inside its carrying some current lol! i always liked looking at the inside of us amps guts!


Yeah, or it could just be 'over wired'...

Posted: Tue Feb 27, 2007 1:00 pm
by Kippo
eezip,
if i take a close pics of the amp, will it help in your analysis?
i'm outstation at the moment so it may take sometime for me to post the pix.

Posted: Tue Feb 27, 2007 11:31 pm
by eezip
Kippo,

I could probably tell you more with a series of close-ups, but without having the unit on a bench you won't know how it performs. And that's what it's all about, right? Crappy components sewn together well can work well, and expensive parts can perform poorly under the guidance of a poor designer or other constraints. If you want to take more pics I'll look and them and let you know what I think, but what you probably should focus on is how the amp performs. Without a unit in my paws I can't help you with that.

Posted: Wed Feb 28, 2007 6:51 am
by Member02
I once owned two revolutions... and I can add that two of them at .25ohms... on four SeXXXs had a ball! they got hot alright, but never shutdown... even at 11volts, lol...

and it measured like .75ohms due to the box... which I was impressed with... ended up with a 147.9db on the termlab that day...

the revolution was a good amp, but really, only did what it was rated a, which is good, but I needed more, so I sold them, one is somewhere in this country, the other has been in my friends station wagon powering my old sexxx for three years now, it's doing fine.

Posted: Sat Jul 28, 2007 9:35 pm
by Sawzall

Posted: Tue Jul 31, 2007 10:28 pm
by eezip
Sawzall,

Good post and thanks for keeping this thread alive :)

You are absolutely right about the loss of information when sampling. But in regards to class D, and you pointed this out in your first paragraph by stating they are analog, they do not sample. The pulse width can assume any infinitesimally small value between [ideally] 0 and 100% modulation [usually it gets a little hairy around the extremes] - there are no 'steps' in a class D amplifier. The system is analog! There are digital modulators which do have steps in them and therefore suffer from the symptoms you describe. However, progress is being made and the HRPWM in TI's newest DSPs allow 150ps steps which can theoretically produce excellent measured audio performance. As with all amps [ok, ok the very first class D amps were somewhat limited by the semiconductor technology and didn't sound good nor have low noise floors], the sound can be tuned and it's strictly dependent on the topology.

If I may ask, what class D amps have you heard? I think UcD amps are anything but poor sounding and ICEpower amps also have nothing to be ashamed of. Both of those are full range. Also, QSC recently released the PL380, a 4kW x2 stereo amplifier that is class D. Although based on a traditional topology [compared with the other 2 I just mentioned], it has excellent distortion numbers and sounds very good. Class D is just such a versatile and expanding field it's hard to make generalizations because the multitude of topologies can perform significantly differently.

In the end what I am saying is that digital encoding suffers [actually, I don't think suffers is the right word but...] from encoding, most class D amplifiers are analog through and through and thus there is no sampling involved.