QuoteYour love of complexity as a virtue is so great you are so obviously blinded to anything that threatens to take that beloved complexity away from you.Like I say, LJ, you don't know me. To someone who does, this is more proof that you don't.
QuoteOf course there is no sound during a short,But you were moaning about tone loss when short circuit protection is activated. Did you not see the problem? Short circuit protection activates... when... there... is... a... short.
Quotebut I seriously don't get how that proves there is no simpler solution. All you proved is you can't see one.The politician is back. If you read what I said, I said that I didn't see a simpler solution. You're the one who's trying to make that be me saying that it proves there is no simpler solution. That came out of your keyboard, not mine. Me not seeing a simpler solution is not proof of anything - other than I'm honest about it when I don't know.
By the way - I do have the professional background, experience and training to make it significant when I say I don't know of a simpler way. I know a lot of ways, just no simpler ones. I've designed a lot of power electronics. What have you designed?
I kinda have this history of saying when I don't know something. I always did want to know not only what I know but what things I didn't know, too. It helps. You ought to try it some time. Practice saying to yourself in the mirror "I don't know [whatever]." It'll make a much bigger person out of you. Did you want me to provide some historical quotes about people who won't admit when they don't know something.
I didn't think you did.
QuoteMaybe one day someone will give you one with permission to use it.Actually I got that permission a long, long time ago. But thanks for thinking of me.
QuoteSorry, but you rattle on about nothing too long to waste space reproducing it for you. But - ok, assume I don't.I already assumed you didn't. In fact your posts showed it pretty plainly. The issue is whether you would admit it.
Quote"Yes", there are some situations where what you are calling "safe-area protection" can prevent an amp from dying.ALL RIGHT!! LET'S HEAR IT FOR THE MAN!! He's growing up!
QuoteBut that does not imply that what you are calling "safe-area protection" is necessary or desirable in all cases.OK. That's fine. My contention was that sooner or later, depending on how you used the amp and how the loading was done, you would run into a situation which would damage the amp, requiring repair or junking the amp. You've fought that contention tooth and nail, only to finally admit that
(a) short circuit limiting does not damage amp tone
(b) there are situations where safe area protection protects an amp.
Only a fool does the same thing in all possible cases. You're trying to press the issue that there must exist at least some cases where safe area protection is not (a) necessary or (b) desireable. Well, duh. At least you've backed off the claim that no protection of any kind is ever necessary or desireable. But we did have to drag you there kicking and screaming.
QuoteWhat you are calling "safe-area protection" isn't because it only monitors one of the variables. Current limiting would be more accurate.Like you finally admitted, you don't understand it. So how is it that you are qualified to act as a critic? If you don't understand it, how do you know what it monitors, what it doesn't, and how accurate it is, both in an absolute sense and a relative sense against other protection forms?
Safe area protection, if well designed, monitors many of the variables that happen to the output devices and start shutting down the output devices when they start getting to dangerous conditions. Well designed safe are protection watches absolute current, current-voltage product, time variance of CV product, and load impedance.
I could give you the lesson about why safe area protection is more accurate than current limiting, but as you said
Quoteyou rattle on about nothing too longso if you ever want to know how it works, ask.
QuoteAnd you can say I was unsuccessful again, but the problem is with the hidden assumptions of your question. Qualify those assumptions and I have no problem with a yes or no answer.No, you did OK. You admitted you didn't understand it. Bravo. You're getting better. Keep practicing.
QuoteRG said: What is your training and experience in analyzing power electronics for reliabilty? Is it just using them until they break or don't break yet?
QuoteLJ said:Yes.OK. So you don't have any training or experience in analyzing power electronics for reliability. Well, no big surprise, but once again, I was just seeing if you were honest enough to admit it.
QuoteReality is fact - theory isn't. If it doesn't break in use, then it is reliable. Bridges built only on theory do fall down, and in doing so, theory changes.And mothers kiss babies and bake their kids apple pies. Who said anything about theory? I've spent more than a few days peering at the burned-out guts of a power supply or amp that let the magic smoke out and designing something that replaced the hulk and didn't die.
People with theory-envy want really badly to tar anyone with formal training with the brush that they have no real world experience. You misjudge it badly if you think that's the case here. I've known engineers who were useless. But I've also known guys with degrees that are the right ones to have on your side in crunch. It's another logical fallacy to assume that theory is always wrong, or that an engineer worth his salt will hold onto a useless theory.
Let me reproduce something that you seem to have missed from my last post:
Actually, my "hearsay" comes from people who practice the art, write textbooks, teach, make a living by getting things to work - over and over and over. I guess that yes, you could call that a better grade of hearsay. Call it informed hearsay. Who you gonna bet on - the guys who do it all the time or the uninformed?
The race is not always to the swift nor the contest to the strong - but that's the way to bet.
QuoteI doubt it, but you may have heard the saying: "when reality conflicts with theory, develop another theory".Yeah, I've heard it. We had a few other sayings back in engineer-land that you probably haven't heard.
"You can't bullshit electrons."
"Put whatever you like in your design drawings, but Mother Nature waits for you at the end of the assembly line."
Your anti-tech bigotry is pretty dated (and herd-following, as I know that's near and dear to your heart) but it's not very accurate. Did you think it's original? Did you think it's clever? If you get right down to it, it's a form of pride in being ignorance; the idea that people who have training and experience in a technical field must be wrong. Save yourself a lot of money - don't get into a lot of wagering on technical issues.
QuoteI will never be INVOLUNTARILY forced to short the output of my amp. That is just one of your hidden assumptions.OK, lessee here. You're never going to plug the wrong cord in. You're never going to get a whisker of wire or metalized foil in the wrong place in less-than-ideal conditions and time pressure. You will never, ever, no-how, no-where, no-time ever make a mistake.
If that's your contention, you are either not human or a liar. And yes, I guess it is fair to say that humans will make mistakes to be one of my assumptions. So tell me, and again, try to answer yes or no - are you trying to tell me that you will never make a mistake?
QuoteThe rule about plugging in the speaker before turning the amp on pertains equally to solid state - you won't short the output by plugging in the cable. Deny that one.Why should I? If you are silly enough to use plugs that will short the output and also silly enough to demand that there be no protection of any kind in your amp, OF COURSE you have to make up rules to try to never make a mistake.
...uh-oh... there's that mistake word again.
What I can tell you is that none of my amps, with the exception of my old Thomas Vox amps, care a whit whether you plug the speakers in first or not. You can plug the speakers in and short the output with a crowbar with the amps being driven to full power and there may be a momentary hiccup, but there's no smoke, no flames, hardly even a burp. More importantly, you can plug any speaker load you happen to find into them, and no combination of loads or lack thereof will have me muttering as I solder in new output devices. Or replace tubes. My tube amps are stable under no-load. I ...um... have that protection resistor in there that I told you about.
The TV amps are special. I keep them in a kind of sheltered workshop for sentimental reasons.
QuoteAnd common sense tells me not to use a long speaker cable, so it's physically impossible for it to be run over.Kewl.
This "common sense" you speak of - is that what you'd call "unstated assumptions" if I used it? Yeah, I thought so.
But back on topic, you're going to use nice, tidy, short speaker cables that will just ...barely... reach from amp to speaker, no trailing wire to roll over or step over here, uh-uh! That's great, until someone trips and knocks the amp off where it's sitting, or knocks the speakers over and breaks the plug in the jack, ...involuntarily... shorting your speakers.
QuoteI don't have a clue what tangent this is.Yeah, not having a clue does seem to be a problem. Let me help.
You said:
QuoteMaybe a corporate engineer would lose his job by designing an SS amp for tone instead of short circuit protection "just in case".The operant words being "for tone instead of short circuit protection". By that juxtaposition, you were trying to draw the picture that designing for tone was leaving short circuit protection out, and vice versa. You were attempting to present them as antagonists. So I said:
QuoteThere is no designing FOR tone and NOT FOR protection (again noting that "short circuit" has nothing to do with it, see above again). The two are not antagonistic concepts.Caught up yet, are we?
It may be possible that you see them as antagonistic because to you "tone" only happens on the edge of circuit failure. If that's the unstated condition in your mind, you need to do some more thinking.
QuoteNo, tone doesn't happen only on the edge of failure.OK, that's a step forward. I hear you saying "I can get tone without running my amp on the edge of failure." We'll come back to that.
QuoteBut with your mandatory protections, tone doesn't happen.First of all, I never said they were mandatory. Smart to have, useful. Something I'd put in, yes. But mandatory? Gracious me, I'd never tell you what you could and could not have in an amp. I might snicker at the choices, but I'd try to do it in private to be polite.
QuoteAgain, since you keep avoiding the question, why don't you recommend these things for tube amps? Wouldn't having them produce a nice glichy sound be equally "great amplifier design?"Avoiding the question? Not at all. I don't recommend them for tube amps because tube amps are not prone to the same kind of failures as SS amps. They are prone to a different class of failures, and didn't I already explain that one a few posts back?
But what you're trying to get me to admit is that I lump making glitches with protection circuits, and further that I think all amps should have glitches. Right? It won't work, because (a) I never said that, and if you misread it what way, go read again; (b) I have the opinion that well-designed protection circuits do not necessarily produce glitches in situations that are otherwise not damaging to the amp.
We have from you the following collection of statements:
QuoteHmm... yeah, maybe I'm lumping too much under the general term "protection circuit". It's the short circuit protection I primarily don't find very toneful.
QuoteOf course there is no sound during a short,
Quote... But - ok, assume I don't(know how safe area protection circuits work).
Quote"Yes", there are some situations where what you are calling "safe-area protection" can prevent an amp from dying.
Let me synopsize some things you've written:
You've used SS amps for a long time.
You are OK with the failure rate you get with them.
You have heard some SS amps with protection circuits in them that you don't like the sound of.
You generalize from that last statement that all protection circuits are bad and should be avoided.
You do not understand short circuit protection circuits or safe area protection circuits.
You admit there are situations where short circuit protection and safe area protection can save your amp from being damaged.
I think the rest of this is not liking being called on it. You'd sure like to paint me as a guy who has no real practical knowledge, is a follow-the-leader automaton, and is technically trained and therefore must be wrong. As you yourself said, reality is fact - theory isn't. The reality is that your theories don't match amplifiers or me.
When you can design a heatsink so the power devices don't burn up, when you can design a multi-slope safe area protection circuit so a set of speakers won't activate it, when you can design and build a transformer driven totem pole output stage will be stable over initial component variance, thermal drift and aging, when you can count off some of the problems with believing a circuit simulator is telling the truth, when... oh, never mind. When you get to any of these and want to know more, drop me an email. I'd be glad to help you with some of the fine points.