class d amplifiers

sedate wrote: heamph wrote: Class D is ANY group of amplifier (including Tri-Path, Class "T", and ICEPower) that uses a full rail-voltage swing, between off and on, in a high frequency PWM method (some amplifiers, up to 350,000 pulses per second ) to drive the speaker cone. While the Tri-Path and the ICEPower use PWM, they adjust the output frequency dynamically, based on the analog frequency. This is claimed to allow for a more effective damping ratio. The reason for the efficiency ratings that you see, is because the output devices are ALWAYS either fully ON, or fully OFF, therefore there is VERY minimal voltage drop (or zero, when in the "off" state) across the device, thus, very minimal heat. Alpine, Eclipse, JL, and I think even Zapco ALL offer full-range Class D amplifiers. Spectron, a home amplifier manufacturer builds full-range Class D, (and were the first to do so, IIRC) and their amplifiers are regarded as some of the best sounding amplifiers in the world today! Are you trying to beat me over the head with syllabes?  Okay look heamph - this is a fantastic explanation - admittedly much more complete than mine my sort of nibbling Best Buy-clerk-style explanation, I think we both know that the basic idea behind a class D amplifier was, and is still marketed as, a low(er)-cost, higher-efficiency amplifier for driving subwoofers.  This is changing I suppose - I don't particularly follow Alpine or Eclipse - I think both make *ugly* gear - but JL does NOT offer any full range class D amplifiers - not thier original amplifiers, not the E, A, TMA, or G series - only the upcoming HD series, due around June I believe.  http://mobile.jlaudio.com/jlaudio_pages.php?page_id=239 Anyway, I was speaking in broad generalities, responding to a generalized question about the overall state of car audio class D amplifiers.  I think if we take a look at our OP: s_goodie wrote: beacuse im really into car stereos and alot of people ask me things on what to look at fora good class d amp and i really am not sure Is he looking for a broad explanation about what a class d amplifier is as a mainstay of car audio?  Or a polysyllabic white paper about specialized, spendy gear which has just been released in the past few months and does NOT represent a particularly large swath of car audio installations?  Or maybe information about home gear that runs on a 120v circuit? Could you dumb it down for us slower people and explain why class D amplifers were one relegated to subwoofer use and have very recently been expanded?  What changed?

So if JL doesn't make it, it doesn't exist or isn't important? Not hardly. The only reason you were corrected is because the information you provided was false. You said, " ...because of the way class d amps are designed, they cannot reproduce frequencies much higher than the standard octaves for a subwoofer system - this is why you don't see a "class d 4-channel" . These are both false statements, as they can reproduce the entire frequency spectrum, and there are indeed 4 channel full range class d amps...

Is he looking for a broad explanation about what a class d amplifier is as a mainstay of car audio?  - Yes, but I would also assume he is looking for an accurate explaination of what a class d amplifier is, not simply a select few amplifiers that are made by manufacturers who may be lagging in coming up with or applying new technolgies(since you said JL doesn't have any of this "new fangled" full range class d stuff in their lineup, we can use their amps as an example)...

Or a polysyllabic white paper about specialized, spendy gear which has just been released in the past few months - Again, false - the Eclispe ICEPower full range class d amps have been out for years, as have the Apline's IIRC. It's not new technology, and it's actually not so "spendy" either.

Could you dumb it down for us slower people and explain why class D amplifers were one relegated to subwoofer use and have very recently been expanded?  What changed? - Well, you can certainly be caught up to the present since you have obviously been left behind in the past few years with respect to amplifier technology.  Read here to update yourself one some full range class d info. I realize the new line of Eclipse amps are extremly ugly, I have the previous generation and they look much better IMHO. But the technology involved hasn't changed that I know of, and there are a few other manufacturers out there that currently employ it in their amps.

You'll have to forgive me for butchering your post and if I come off as rude or condescending in my reply I apologize, but don't be so quick to jump on someone for making a correction that was clearly justified.

-Matt

greenbronco wrote: So if JL doesn't make it, it doesn't exist or isn't important? Not hardly.

The statement was that JL offers full range class D amplifiers.  They don't.  They certainly are *marketing* full range class-D amplifiers, but they are not *offering* them.

Which I feel we are still somewhat lacking - again, I admit that I provided a

but it seemed most appropriate given the general thrust of the OP.  Anyway, I wasn't replying to you, but since you are so smart bronco, and obviously have copious, untapped writting skills, why don't you pick up the gauntlet and

I do it all the time. 

So you link to a commerical?  This is useful information:

http://www.ee.ucr.edu/~rlake/EE135/Class_D_amp_notes_AL.pdf

This link you provide is not.  It's a commerical - it is designed - sort of the way heamph's post came off - to throw as many large words and acronyms together to sound authoritative and not really explain anything.  When I read twenty proprietary acronyms in a web page that stopped by the marketing department before being posted - I have a hard time distilling an explanation. 

heamph - this part makes sense:

Okay - so what I'd like to learn is why did this start out as a low-frequency only technology and remain so for so long?  I've read lots a stuff about why this is great technology but totally untenable for higher frequencies - admittedly some time ago.  So, I ask again, what has changed?  Are the JL's, Eclipse's, and Alpine's all using basically the same solution to this apparently solved problem? 

sedate wrote: greenbronco wrote: So if JL doesn't make it, it doesn't exist or isn't important? Not hardly. The statement was that JL offers full range class D amplifiers.  They don't.  They certainly are *marketing* full range class-D amplifiers, but they are not *offering* them.

Exactly what I said; JL doesn't sell a full range class d amplifier that I know of, but again I don't folow JL products because better can be had for the money IMHO, but that's beside the point. My point was simply that; to me, it seemed as though your train of thought was that just because JL Audio does not make a full range class d amp, that they didn't exist or are not "mainstream", and this is simply not true.

What does it matter who you were replying to? The information you posted in your reply was WRONG and you were called on it. Now it seems you're all pussy hurt for some reason, and will have to get over it. I claim to hold no more knowledge than I actually have, and I will flat out tell you that I can not provide an explaination as to how or why class d amps do what they do. But, I do know enough to recognize incorrect(or incomplete as it were) information when I see it; especially when I use the technology in question in my own vehicle. An explaination has already been provided, if you require a a more "dumbed down" version as you called it, then go search for it - I never said I could give you one...

The link I provided is all I have have access to at the moment, being that I am at work and can only view certain websites due to a lame ass internet filter. I'm sure that someone with more knowledge on the subject can fill us all in a little more on how the technology in question actually works; hopefully in a sense we can understand.

EDIT: Here is an article written on PWM power supplies and class d amps, and there is some full range info in there as well. Notice the artice was written in June of 2005, and DOES touch on the advancements in (then) current class d amplifier design and how it IS possible to create a full range class d amp. And it is in terms even you and I can understand.

Most of your questions will be answered in the 2nd article I provided. As far as the brands using similar technology, I believe the ICE power technology was designed by a company called Bang-Olufsen, but there's no mention of the technology on their website.

-Matt

Also, just for anyone wondering about the usability/efficiency of ICEPower(actually the Eclipse XA line specifically) class d amps, you can read the thread here where a few guys had used them, some ran tweeters off of them, and a few others actually compared them to higher-end amplifiers such as those from Zapco and Arc Audio...

-Matt

Because you admit the explanation is over your head.

Heh you posted something helpful!  And look - free of useless, proprietary acronyms like "ICE" that came from a marketing department!  Thanks bronco, I'll enjoy looking that over.

Dude.  I'm really, really sorry. 

Class D amplifiers were *originally* (have to be careful for rousing the peanut gallery) designed (as implemented in the car audio world, I know nothing of where they really came from) as a solution for high wattage amplifiers in a 12v, low voltage environment.  They are substantially more efficient - less voltage in, less heat, etc. - than other amplifiers that push your cabin speakers.  This allows weaker electrical sources - like the alternator in a car - to power high wattage subwoofers.  This is really the distinction I look for when I see "class D"

I have now learned, this has been expanded very recently - it appears by Fujitsu with thier Eclipse subsidiary first - then by Alpine and now JL.  This technology seems to hold much promise.

If I were looking at a traditional class D amplifier, look at efficiency ratings - something on the order of 80% or so I believe is a tidy number for a quality class D amplifier.  However, in terms of your OP, you generally want to select an amplifier from a quality manufacturer - Alpine, Eclipse, JL, any of the brands we've been arguing over are good places to start.

A (traditional) class-D amplifier is an amplifier that is more efficient than a traditional, full-range amplifier (class a or class a/b) and thus good for high wattage applications where input power is limited - but is restricted in that it cannot play speakers other than subwoofers.  There are a few exceptions to this definition, but I wouldn't consider them important enough to discuss - as we clearly lost you in our petty one-ups-manship.  Again, I'm sorry.

Are there specific amplifiers you are thinking of?  Could you link to them?

I'm sorry we argued all over your honest question.

Wow.

All this over a Pyramid!  Ha!

Okay - this is an extrodinary cheap amplifier and I wouldn't allow it near my car.  Honest.

It doesn't put out 4000 watts unless it is buried in dry ice and getting 20 volts. 

It isn't a class D either - is MOSFET its own classification?  I think MOSFET means the amplifier coil is integrated onto the mainboard or something... I dunno - its not class d anyway - its a full-range amp.

I mean - if you are only considering because you can get it "for really cheap" my reply would be only if "cheap" is >$40. 

I wouldn't expect much of anything out of it.

Wish I could tell ya somethin ya wanted to hear.