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#18966 - 12/20/02 05:37 PM Re: Digital amps
Matthew Hill Offline
Desperado

Registered: 11/29/01
Posts: 1434
Loc: Mount Laurel, NJ
"Wrong," said Renner.
"The tactful way," Rod said quietly, "the polite way to disagree with
the Senator would be to say, `That turns out not to be the case.'"



------------------
Matthew J. Hill
matt@idsi.net
_________________________
Matthew J. Hill
matt@idsi.net

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#18967 - 12/21/02 02:08 PM Re: Digital amps
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Wow. I go away for a few days and lookit what happens.

Digital amplifiers operate by definition by switching fully on or off quickly enough that the average output over some time constant is roughly equal to the desired output.

The switching 'on duration' and/or frequency can be modulated to accomplish this. The practical effect is a variable duty cycle.

An unavoidable side effect of this switching is switching noise. This will be manifested as a tone or range of tones above the signal frequency. If the load is known and/or guaranteed to be inductive the amplifier can be configured to safely drive the load directly, but if the load has or may have significant resistive or capacitive components, especially near the range of 'carrier' frequency(s) an inductor must be placed in series with the load to filter the switching current.

If the carrier frequency(s) is sufficiently higher than the signal frequency(s) the filter may be designed such that it is well out of the way of the signal, but if they are anywhere near each other this may not be possible. In this case the filter must be carefully matched to the load such that it is effective without distorting the signal. If this is still not possible it may be possible to alter the input prior to amplification in a manner complementary to the filter effect.

If this carefully matched system is exposed to unexpected loads the upper frequency response will tend to droop as load decreases. This effect can be observed in this ICEpower document:

http://www.icepower.bang-olufsen.com/sw1166.asp

The frequency resonse is down 1-2 db for 2.7 ohms. Some loudspeakers have made it to market that dip lower than 1 ohm.

Now it is true that this would be exceptional frequency response performance for a loudspeaker or maybe a few other classes of components, and the linear distortion is minimal when taken in a holistic 'impact on system' view, but as consumers we are accustomed to better from our amps.

Of course the amplifier may drive such a load without obvious distress from a power distribution sort of view, but this isn't power distribution.

The folks at Acoustic Reality and the reviewers at High Fidelity both assert the eAR has this fixed, but haven't backed it up with any published tests or IP that are germane to the issue. The base ICEpower module is better than most, but still exhibits the issue. So maybe it's fixed, but I'm a 'show me' kinda guy.


SLL:

Quote:
I apologize to the forum as a whole.


Not needed. You are also entitled to free expression. Nice of you to say though.

I suspect AzRyan is probably a very nice and personable fellow in real life. Real life interpersonal skills are often not easily mapped to a forum like this and it should be expected. Let it roll off your back, and try to concentrate on any content that may exist. I've learned a few things from him and I'm thankful for it. I'd be thankful for more relaxed presentation, but I'll take what I can get. If we were all the same the world would be a boring place.

EDIT:

The massive improvements in this area as represented by the ICEpower module and others make me think the future is bright for class 'D' audio, but for me it's got to get a bit more mature before I'd jump, that's all.

[This message has been edited by charlie (edited December 21, 2002).]

[This message has been edited by charlie (edited December 21, 2002).]
_________________________
Charlie

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#18968 - 12/21/02 06:16 PM Re: Digital amps
Smart Little Lena Offline
Desperado

Registered: 01/09/02
Posts: 1019
Loc: Dallas
Real life interpersonal skills are often not easily mapped to a forum like this and it should be expected. Let it roll off your back, and try to concentrate on any content that may exist. I've learned a few things from him and I'm thankful for it. I'd be thankful for more relaxed presentation, but I'll take what I can get. If we were all the same the world would be a boring place.

Graciously stated, (and you remind me, -I do not LIKE to be bored ) you are man of great restraint I commend your 'style' Charlie Thank you.

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#18969 - 12/21/02 08:11 PM Re: Digital amps
azryan Offline
Gunslinger

Registered: 09/10/01
Posts: 222
Turner -"Your posts are patronizing and it offends me that you have the gall to make some weak analogy justifying your rudeness with the bombing of innocent civilians."

The only problem here is that I DIDN'T do that. You just put those two points together yourself.

I was talking about an issue greater than this fairly pointless thread (of which I think the lives we've taken overseas certainly is), and the way people in general often poorly judge things and perceive right and wrong. Meaning whether a pointless issue like this thread or a very serious issue like bombing innocent people.

I hope that clears it up for you.

If you don't like my comments and really wanted to twist what I meant... you could've claimed I meant that my rudeness is as bad as bombing innocent people. Then you would've really made me look horribly evil.

Pay closer attention to charlie. He's very good at twisting things like this. It may help you in damning me in the future (if you choose to), but I think you've got me wrong.

You also mentioned that charlie said "-the output filter that all class D audio amps must have will typically cause them to have frequency response problems on difficult loads."

He doesn't know what the actual output is of any digital amp. He likes interpret data he reads (read: "guess") about the digital amp modules themselves.
This is far from what the end result can and typically is from actual digital amps on the market (of which he's heard and tested ZERO), but I've been talking about only ONE here anyway..., and most importantly it doesn't work like other class D chips.

The review said "-We have tested the amplifier with a number of loudspeakers, and the amplifier is not particularly influenced by the loudspeaker it is connected to. This is rather diff. from other switch mode class D amplifiers where the amplifiers have always played differently with a number of diff. loudspeakers."

You put those two together Turner, but the review comment is NOT the same as charlie's faulty 'guess' on freq. response problems.

Did you see the term 'freq. response' anywhere in the reviewer's comment? Did you see the freq. response graphs in the review? They're flat.
The reviewers called it the most accurate amp they've ever used. How could they say that about an amp that had poor freq. response??

But you think charlie made his point about class D (-at least somewhat because you understood that he was flat out wrong about the eARTwo amp), but you've been tricked.

So I get mad that he tricked you... and for that you get mad at me. Bad logic IMO, but certainly very common in our country.
He's the guy knocking this amp. I'm the one who told you about it.

And since this is specifically about the eARTwo amp (not any other class D amp). All the more reason to get mad that charlie ignores the review's info since it states that this amp isn't influenced by various loudspeakers.
It doesn't work like any class D amp though it is digital. Charlie says they all work the same.

Charlie talks about speakers that dip down below ONE ohm. That's so overboard it's not even funny!
He's just grasping for ANYTHING to call wrong with this amp, and even when he goes to this crazy extreme (though with a smile -so everyone thinks it's fine) he's still wrong!...

1) no one here (including charlie) has speakers that dip that nearly that low so the need doesn't exist for 99.999% of us for any amp to handle that load.
2) It's a rare solid state that can handle that imp either.
3) the eARTWo can handle it anyway.

Email the amp's designer and ask if the amp can handle your speakers. It'll be 'no problem' every time.

And it has NOTHING to do w/ the money I paid for the amp either Turner. I'm sure you'd like to think I'm here bragging about 'this cool amp I've got', but you're wrong.

I've been trying to explain this technology to Outlaw fans like you and to the Outlaws themselves in hopes they'll attemt an amp like this. I've said this exact remark MANY times in this thread!
My amp probably shouldn't be as costly as it was, but you have to pay for R&D not just the parts w/ small high end companies making state of the art products.

Soundhound -there are speakers that have plasma tweeters. They produce a lot of ozone, but they exist and you can buy them. Probably the best tweeters in the world, but the ozone problem isn't very cool.

You said "-I find it hard to believe that he would waste your's and everybody's time by intentionally lying about amplifiers, or anything for that matter."

So do I, yet I keep showing how he's actually do just that.

Think about his motives... he has NO interest in trying any actual digital amp of any kind in his own system so why does he even care???

You can get this amp w/ a full refund return policy. If he wanted to test it and return it he'd be out a small amount for shipping. He'll NEVER do it. And no one who heard it would want to send it back as it would be audibly better than their previous amp -as long as their speakers and other electronics were of good quality.

I have probably one of the worst systems of any eAR amp owner. Most owners have massivly high end gear from speakers to wall outlets and everything in between.

There are other digital amps like the PS Audio HCA-2 w/ the same refund trial deals.

I have a PS Audio dealer here in town. It's a Stereophile Class A by the way (as is the digital Bel Canto eVo).
The eARTwo has been called better than both of them by several people in not having any trace of digital dryness, and it's tight bass, most realistic high end they've ever heard, etc...
I find the eARTwo worlds better than the digital Tripath based amp I also own.

You added -"There are obviously reasons for his stance on the issues in this thread, but I doubt that intentionally lying is one of them."

There are obviously reasons..., but the reasons aren't obvious.
What do you think they are? Honestly. I'm not being a smart ass here.

Why do you think he tries soooo hard to say that this amp is no good?
He's never even heard it! He doesn't know what's inside it. He doesn't know certain measurments that he acts so deperate to know (or guesses that they're poor) yet all the measurments posted are exceptional.

I think it's just to 'look right' at ANY cost since I keep showing how he's totally wrong.
He never gives up, and in America not giving up can make you look right to those who don't really know even when you're not right at all.
(as evidenced by our president's high approval rating).

He judges this amp as not being good enough though he has never heard it, and twists the facts since this amp's output is NOT the same as the raw ICEpower module who's data sheets he foolishly continues to make remarks on.
How many times do I have to correct the same points before I get to get mad? Maybe Lena might say 'never'? I don't.

He ignores the professional review's data and comments (and every audiophile who owns the amp) -calling it the best amp they've ever used.

Charlie's bad data tells us it's not more powerful than a 100-125W solid state amp and it has poor freq. response.
Outright lies. You think he doesn't mean to lie, but what do you think he means to do???

He says -"The frequency response is down 1-2 db for 2.7 ohms."
He refers to the ICEpower module which is NOT the same output as the actual eARTwo amp. I've said that over and over yet he keeps twisting this point.

The designer spent over 2 years working on this amp, he didn't just slap a power supply to it and mark up the part costs.

Even the designer says the raw module doesn't sound very good in raw form. There's more to the amp than that.

He managed to make the eAR amps sound incredible though in the opinion of everyone who's bought this amp and posted a review online (and there are quite few). They measure great too. There's no downside to them. It's world class accuracy.

Jeff Rowland is coming out w/ ICEpower based amps too soon. I guess Charlie should explain to this very famous world class amp designer that he's wrong about using this module too.
It'd be funny if I weren't so sick of this damn game.

He says
"The base ICEpower module is better than most, but still exhibits the issue. So maybe it's fixed, but I'm a 'show me' kinda guy."

He contradicts himself here.

He says it still has the 'issue' but then admits that 'maybe it's fixed'!?!?

The professional reviewers who used the actual amp, and tested it with several loudspeakers certainly think there's NO problem, but what do they know right?
They only call it their new reference amp, but charlie knows better. Hard to guess who's right hey?

Or charlie's comment on class D amps -"An unavoidable side effect of this switching is switching noise."

The ICEpower module doesn't use pulse width modulation unlike all other class D designs. This is the main benefit of this module. I've said this already too.

The eARamp itself has a super low noise floor, and the most accurate signal these professional reviewers have ever heard.
I have to place my ear to my Newform ribbon to hear even the faintest trace of noise from this amp (this changes when I turn the 950 on as it has far more noise).

I told him to buy one and test it if he wants to talk about it's performance.
But he won't EVER do that. Guessing and twisted conjecture is good enough for him.

He doesn't want this amp and doesn't care if it's as great as the numerous claims say it is. He said himself he doesn't trust his ears so he doesn't even care if this amp sounds good to him or not!
And for all his comments on poor design he doesn't even have a speaker set up that could let this amp's attributes show through.

In wall speakers (sound bounces off the huge wall baffle and the drywall vibrates)
They're ~16' apart. (much too far apart to have any kind of imaging or soundstage quality in any way. Not even if they were angled in which you can't do 'cuz they're in-walls!)
One right next to a wall. One by an open area (making freq. response diff. between the two as one gets wall echo and the other doesn't).
Dual tweeters (as they play the same high freq. sounds that are smaller wavelenths than the tweeters distance apart the two outputs comb).

An audio tester/reviewer couldn't hardly set speakers up much worse if they tried, and this is his design.
Yet he judges this amp he's never heard nor tested contradicting pretty much every finding of these professional reviewers??

If he doesn't mean to be a troll I have NO idea what he thinks he's trying to do here!

If he wants to wrongly talk details about what this amp can and can't do he's gotta look at his own set up first and it's poor design.

He sums up with-
"The massive improvements in this area as represented by the ICEpower module and others make me think the future is bright for class 'D' audio, but for me it's got to get a bit more mature before I'd jump, that's all."

That's a VERY well written line.
It makes him sound like he actually understands what he's talking about. Sadly (and now angrily)... he doesn't.

ICEpower's modulation is unlike all other digital amp chips.
The eAR amps are totally unlike the raw output of the ICEpower modules.
Professional reviewers are calling it the best amp ever made.

Even if it's not the best (which could be forever debatable), the technology of this amp is so far from 'it needs to mature' it's insane for someone to say such a thing, and I feel it must be for no reason other that to damage my posts or to make himself 'look right' truth be damned.

The 'bit more mature' part is NOT this technology. It's in him understanding these critical points I've just made and him stopping with the twisted bits of info and wild imagination that just don't add up to the actual real world findings.


Oh and Lena you said
"-It's NO excuse. But I'll say it anyway and espcialy to Azryan. As I tiptoe back into the forum this morning thinking, "did I say that?". I was back in the courts from 9 to 3 pm the day before that post for the second time in 7 days. Having to be sworn in and testifing again about 'men behaving badly' in the neverending divorce."

'The neverending divorce'? Uh..... I have NO idea what you're talking about??
If it helps you I get along great with my wife if maybe that's what you were getting at?? She was floored by this amp on the first day we got it also.

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#18970 - 12/21/02 08:38 PM Re: Digital amps
soundhound Offline
Desperado

Registered: 04/10/02
Posts: 1857
Loc: Gusev Crater, Mars
azryan:

Quote: You added -"There are obviously reasons for his stance on the issues in this thread, but I doubt that intentionally lying is one of them."

There are obviously reasons..., but the reasons aren't obvious.
What do you think they are? Honestly. I'm not being a smart ass here.


I meant that I get the sense that he isn't intentionally lying, beyond that, I don't know what he is or isn't thinking.

I wasn't aware that someone was actually manufacturing ionic tweeters. That's wild! I know that one of the main dis-incentives to owning them was the ozone, and the high voltage power supply involved.

Do you have web links to any 'white papers" about your amp? I'd be curious to read about the technology involved.

[This message has been edited by soundhound (edited December 21, 2002).]

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#18971 - 12/21/02 11:18 PM Re: Digital amps
Smart Little Lena Offline
Desperado

Registered: 01/09/02
Posts: 1019
Loc: Dallas
If it helps you I get along great with my wife if maybe that's what you were getting at??

BIG APOLOGY, NO...I hope everyone here gets along with his wife. I was goofy in a past post on this forum and was referring back to that (without detail). I have been in court 3 times in the last 1 ˝ wks. Its 2 + years and still not settled and with children involved heavy on my mind. I'm the only personal (non-professional) witness, called, as I was both parties friend since onset of the marriage and am fairly well known around here for being equitable. I have to testify to some terrible choices the husband made throughout the years. It’s been stressful and very surreal most times (it really is like Hollywood) with 'his' lawyer yelling at both him (her own client) and me on the stand last trial date. After we both declared we do consider ourselves to be friends.

My running around here with my hair on fire, was a grief/rage reaction to having to spend too much time contemplating recently the unanswerable issue of why people treat each other so badly even people they love, often ending by destroying themselves utterly in the process.

Back to the lighter topic of perfect amps. AZ, I’m fascinated with D class, (why I always try to skim these threads) if you followed some of my earliest posts I came into Outlaw early on asking about opinions here and fully intending to buy a Bel Canto. I reigned myself in at the time, and decided to watch the technology gain a little more leg first. Your model looks like one I'd like to personaly demo and I've seen some great reviews. (I really intend to wait till this trickles into multi-chanel versions) But when you become so passionate about the specs and bench tests, it has the opposite effect (on me at the moment) of what you desire. You battle to convince us that that the technology has crossed the hump and (even hit) the summit. I can’t ‘hear’ you for the other stuff flying around. Try just remembering that when you’re speaking about the big reviewers who start calling a piece ‘reference’ that there's always another professional who prefers another choice/technology. Charlie has every right and is no different than a professional reviewer in having his own opinion including the right to base his thoughts on the technology (as he sees it on paper} till he hears one.

I seem to remember your standing on the opposite side of a ‘have not tried it yourself’ argument in this forum when many were resistant to your hard stance taken against others opinions of the benefits of an SPL meter. Yet you earnestly desired to have your own opinion on that topic, per theory and paper and were not very pleased to be told you should ‘try it yourself’. Perhaps Charlie has those rights also?

I sincerely hope your VERY happy with your wife, and if not (please don’t tell me right now anyway)


[This message has been edited by Smart Little Lena (edited December 21, 2002).]

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#18972 - 12/21/02 11:26 PM Re: Digital amps
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Like I said:

Quote:
switching 'on duration' and/or frequency can be modulated .... practical effect is a variable duty cycle.


There is no other way to do a digital amp. This is practically the definition of a digital amp. And PWM has had company for years - PFM. Now we can create a variety of hybreds, but the essence of the thing remains unchanged.

Creating waveforms with switching devices has been around longer than almost anyone here I'd bet.
_________________________
Charlie

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#18973 - 12/21/02 11:32 PM Re: Digital amps
azryan Offline
Gunslinger

Registered: 09/10/01
Posts: 222
Soundhound (or anyone else who cares) -here's a speaker w/ a plasma tweeter-

http://www.acapella.de/english/violon.htm

The only white papers to read are on the ICEpower module in the amp. The eARTwo uses the analog modulated version.
http://www.medicom.bang-olufsen.com/sw1273.asp

The rest of the details of the amp are Peter's (the designer's) secret. The 'rest of the details' make the output of this amp very diff. from the raw module.

The most information from him is on the Harmonic Discord forum. Peter's spoken probably all the details he's ever going to on that forum. He posted some graphs there too.
He said he's spent something like over a hundred grand and two years developing the amp so I think it's understandable he doesn't want anyone to exactly understand how he got it to do what it does so they can just copy the design.

I think I probably won't post here much (or any) more. Doesn't seem worth it to try to tell people here things, esp. w/ charlie here. I'm sick of him so I guess he wins.

I think that means the people here who would like to hear about more cool stuff from me lose, but oh well.
I've yet to see Outlaw actually make anything anyone's asked for anyway so I get nothing out of trying so hard here.

Off into the sunset...

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#18974 - 12/22/02 12:04 AM Re: Digital amps
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
In wall speakers (sound bounces off the huge wall baffle and the drywall vibrates)
They're ~16' apart. (much too far apart to have any kind of imaging or soundstage quality in any way. Not even if they were angled in which you can't do 'cuz they're in-walls!)
One right next to a wall. One by an open area (making freq. response diff. between the two as one gets wall echo and the other doesn't).
Dual tweeters (as they play the same high freq. sounds that are smaller wavelenths than the tweeters distance apart the two outputs comb).


Actually this turns out to be not so.

I've been measuring this with a variety of signals and instruments (for verification) and in fact the response of all the speakers from anywhere on the sofa is identical within +1 -2 db. They are also flat to less than +-3 db with the exception of a minor peak around 6Khz that I'll be tweaking with a filter. This result is actually a lot better than I expected although it's of course far from perfect.

They of course have some early reflection issues on the wall I'm going to try to tame w/ foam but there's no way to really get it all. A few other things will never be right too, but overall it's going to be fine for HT and it was all I could do within the constraints I had. I have to live in here too.

As for 'toe in', any speaker with a wide enough directivity pattern won't really need it. It mostly provides visual improvement, although directing the radiation from a near wall can't hurt either. I'd think the Newforms would have a uniform enough radiation pattern to negate the 'toe in' requirement, but I'm not sure of course. As long as polar response is uniform you're golden.
_________________________
Charlie

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#18975 - 12/24/02 02:51 PM Re: Digital amps
charlie Offline
Desperado

Registered: 01/14/02
Posts: 1176
Quote:
The rest of the details of the amp are Peter's (the designer's) secret. The 'rest of the details' make the output of this amp very diff. from the raw module


Wht secret? There are two possiblities likely here. Either something is original and therefore potentially IP (typically can be protected by a patent) or a 'trade secret' which can be kept for competitive advantage but is not patented for whatever reason.

I doubt you signed a contract with a reverse engineering clause when you got your eAR, so any trade secrets are there for the plucking and not terribly secret.

So why not gain competitive advantage by being public and specific with this 'new' invention? Why not create IP for the company and inventors by protecting the 'invention'?

If it smells like marketing and looks like marketing it might be marketing.
_________________________
Charlie

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