| Columns Retired Columns & Blogs |
| Loudspeakers Amplification Digital Sources | |
Analog Sources Accessories Featured | |
Music Columns Retired Columns | |
Show Reports | |
Features Latest News Community | |
Resources Subscriptions |
© 2024 StereophileAVTech Media Americas Inc., USA
All rights reserved
Since we are dealing with POWER amplifiers, which need to deal with both voltage and current, which is power W, in order to provide max power transfer, impedance matching is necessary. Look under the Reative section of the explanation, not resistive, which doesn't pertain to loudspeakers. An audio amplifier is a power amp, not a voltage amp, not a current amp, not a servo amp, not an op amp. power. And thusly it is like it says like I said before a modulated power supply, impedance matching does matter. WHY does your McIntosh have taps to MATCH different load impedances? hmmmm, if impedance didn't matter, or matching it, does it use taps on tube amps> Please continue...............and can you find a definition of a dictionary in a dictionary? What about a definition of an encylopedia in a dictionary, or an explanation of both in an encyclopedia?
I think the warning is still in place regarding Wikipedia; people posting there might not know any more about the subject than the people turning to Wikipedia for answers. Never the less ...
From your first link;
From your second link;
JV:
If the amplifier cannot drive enough current into a given load then its output impedance has risen.
Or, it is current limited to keep it from going up in smoke.
You really can't be suggesting a $129, 1200 watt 7.1 HT receiver that cannot deliver sufficient current into a real world loudspeaker is unable to drive a low impedance load simply because its output impedance has risen. You don't suppose the more appropriate reason for current limiting such an amplifier would be it just doesn't have a power supply capable of delivering sufficient amperage to low impedance/high phase angle loudspeaker loads?
Telling me its output impedance has risen is giving me a symptom of the problem. I am after the root cause of the problem. Rising output impedance is not the problem. Even if it were, this would only address issues of low impedance (with difficult phase angles) which is still a very small portion of the frequency response of a typical loudspeaker. Remember, the original question is whether the amount of "amps" an amplifier can deliver is a sign of a better amplifier. Just stating a low impedance does not receive as much power as a higher impedance is over simplifying the problem. A low impedance with a benign phase angle is still a relatively simple and easy to drive load for most amplifiers. If I have a four Ohm single driver its impedance is relatively stable and the electrical phase is virtually non-existent. How would that be a problem for a reasonably well designed and adequately built amplifier?
I don't know the answer to this question, but just because a tube amplifier with a transformer coupled output has various taps labeled with different load impedence values, does that mean that the 8 ohm tap has that same output impedence or just that that tap works best connected to an 8 ohm load?
The latter. Though connecting to an alternate tap might produce what is considered "better" sound. It depends on the amplifier, speaker and listener as to which tap sounds best.
If its in current limiting mode its output impedance increases, thats how currrent limits work.
It may have risen for a variety of reasons, lack of PSU capabilty, bipolar gain droop in the output stage, current limiting yack yack yack.... but its output impedance will still have risen.
Its a cause, you should ask why has the output impedance risen?
What? You get to ignore a question just to give a set answer? How do I discuss anything if the only answer possible is "rising impedance"? This seems to be a circular discussion where the only answer is the same to all questions.
"When did you stop betraying the dictator?"
Hi guys
When does this thread come out in paperback? -- I must buy a copy
Buy the encyclopedia version. It has definitions.
Russ is completely correct. Any reduction in output power is due to some kind of output resistance. It can be in the speaker cable, the amplifier output circuit, the output drivers, the power supply filter, the power supply transformer or even the wall outlet.
Try doing some simple ohms law calculation using a simple series circuit consisting of three components.
1) a voltage source
2) an output resistance (our variable)
3) a load resistance
Show me any answer other than maximum power to the load with the output resistance being zero.
What's the definition on an encylopedia?
Zero resistance is a short, nothing but full current then poof! With zero resistance you can't develop a volaatage across anything..if all you have is current and no voltage, how can you have power Since P=EI...but is there really anything with zero ohms, that would be a super conductor, which ain't in audio yet, only super hearing. And depending on the angle of when the conduction occurs also defines the max current at that time. Ya can't use Ohms law in reative ckts like a loud speaker, what's the freq Kenneth?
I thought that no one would ask.
en from the word enclosed.
cyclo meaning wheeled vehicle (unicycle, bicycle).
pedia meaning two legged. (pedestrian)
An encyclopedia is an enclosed two legged wheeled vehicle.
Your welcome.
I want one!
Look it up. It's in the dictionary and you know how to spell the word.
That's all well and good but it doesn't address the original question or anything other than the momentary low impedance load an amplifier might see at a specific frequency. Being correct is not being relevant to the discussion.
Let's try these again.
A low impedance with a benign phase angle is still a relatively simple and easy to drive load for most amplifiers. If I have a four Ohm single driver its impedance is relatively stable and the electrical phase is virtually non-existent. How would that be a problem for a reasonably well designed and adequately built amplifier?
Tell us how many three Ohm speakers are on the market.
If an amplifier must have a low output impedance of roughly 0.02 Ohms to deliver full power to a load, how does an amplifier with a relatively high output impedance of 1.5 Ohms deliver power to any load?
It's a matter of ratios. The greater the ratio of the load relative to the source, the less effect load variation will have on power transfer to the load. As for the original question, I'm not really sure what it meant. Speaker impedance ratings are meaningless because of their variations vs. frequency.
May be helpful to this discussion
Please see a seminal paper here http://www.counterphase.com/stuff/Thiessen.pdf
THAT'S IT!!!!!!!!! See, amplifiers are basically power supplys, I said before, AND Impedance matching....shall I say......no magic, just basic electronics, electrical concepts. AND, they knew that in 1930!!! JV, see how they mention a matching transformer, like on teh McIntosh to impedance MATCH!!! No magic none of this, whatever you THINK sounds better, it's all electrical design, can be measured, documented, tested. Maybe it's a good thing JGH ain't writing anymore, he may have tried to make it all just imaginary personal preferences, when it's all measureable, and calculable. Ask Thiessen. Impedance matching, what a concept based in electrical parameters, not personal preference, imagination, and descriptive words that have no real clarity. Maybe Julian Hirsch had it right all along Also back to the origianl premise, lotsa watts, which means lotsa current, with the voltage to keep it going, that's called a great POWER SUPPLY, all else is not capable of hi fi.
Seems we're back on the circular driveway again.
That was the original question of the thread, Russ. I don't think there is an ideal amplifier but I believe "reasonably well designed and adequately built amplifier" is explicit enough that we do not have to dance around words for a few more days. The question was about the load not the amplifier.
Given what preceded my reply, your response is jibberish.
Maybe I'm wrong but I believe you have this backwards. If the amplifier had its way, its output impedance wouldn't rise and all amplifiers would be happy little creatures with a simple life. Of course, that won't happen since an amplifier must drive a loudspeaker to do its work. Therefore, if we are discussing a "reasonably well designed and adequately built amplifier", I don't believe the problem is rising output impedance of the source but rather it is falling impedance and reactive nature of the load. One is the problem while the other is the symptom. But merely stating a low impedance load as you have done does not suggest the speaker load makes life difficult for an amplifier.
You are once again giving back a non-response. Try to keep the steering wheel straight so we can get off this driveway.
That begins to answer the original question. All else is wasted verbage.
What do you consider "perfect"? An amplifier with the lowest output impedance in all cases? That would make life simple when choosing an amplifier I suspect though it would certainly lead to a lowest output impedance race amongst designers. No more listening as dup suggests. "Just give me the facts, m'am, lowest output impedance or not. Either it is and I buy or it's not and I walk." Goodbye tube amps, goodbye demo rooms and goodbye Stereophile. Once a year JA just prints a product guide with nothing more than the output impedance of each amplifier.
To use your logic once again; what do you consider "typical"? A modern day tube amplifier? A classic tube amplifier? A high end tube amplifier? A cheapo from China tube amp? A push-pull tube amp? A SET tube amp?
I think we can both agree a "typical" tube amplifier's output impedance is probably going to be higher than that of a direct coupled solid state amplifier.
A few days back I stated this argument is over simplification of the idea. I've agreed to the idea that a low output impedance will deliver more power to a low load impedance. I've disagreed with the concept of "power". Watts cannot be divorced from voltage and current. Speaking of only "power" or only "watts" is a discussion that belongs on paper in a first year engineering class.
Once again, here are my points.
If the amplifier is not faced with a low impedance load in a highly reactive loudspeaker, which amplifier delivers the most "power" is not the issue.
Not all loudspeakers are low impedance, highly reactive loads.
Whether or not a low output impedance can supply more "power" to a low impedance, highly reactive load is of minimal consequence when even those loudspeakers that are low impedance and highly capacitive loads at some point in their frequency response are only so through a very small portion of their frequency response. As impedance rises and electrical phase comes closer to zero, the amplifier with a higher output impedance is going to be capable of power delivery that is negligibly less than the amplifier with the lower output impedance. We are arguing over something that is only of value to a small portion of what the amplifier sees as a load.
Is "power" then the only qualifier of quality in an amplifier? (dup, please don't go off on 1400 watts and SLAM.) That is close to the original question. If it is, and low output impedance gets us more power, the discussion is over since I cannot agree to those premises and I'm wasting my time here.
Once again to use your logic, you've been given that answer.
I understand that. The question of a high output impedance was rhetorical in nature since we seem fixated on the lowest possible output impedance. Some here seem to see this as an issue of the source while I prefer to look at the discussion as a matter of the load the amplifier works into. Mating the correct load to the appropriate amplifier seems to be the wisest choice IMO. If you prefer the sound of a SET with a high output impedance, finding the appropriate speaker for that amplifier is essential. If you feel only amplifiers with output impedance numbers in the triple naughts will do, then you've closed your ears to a great number of very good sounding systems.
Let me interpret the o.p. as asking whether all high current amplifiers sound "better" than a lower current device. Does the current capability of an amplifier dictate it's sound quality?
That is exactly my point. Discussing whether a lower output impedance makes any amplifier "better" ignores too many issues where low output impedance is not an important consideration. Personally, I would rather have a very good sounding tube amp with 1.5 Ohms nominal output impedance and the appropriate speakers to mate with that amp than a cheap receiver with low output impedance derived by way of high N.F.B. ratios driving a low impedance, highly reactive speaker load.
Who's the webmaster of this board? Can we suspend Jan for spreading sheer boredom across these forums? How about for necrobeastabuse? At least when DUP rants, it's entertaining. Jan is like Chinese water torture. Perhaps we can shrink him, put him in a petri dish and just let him bask in minutiae.
The Maths is actually correct for ANY load impedance (low impedance also occurs at mid-range frequencies as well). If you want to give me some specific numbers I
Well a pretty case and made out of solid alumininum may pass your definition. How about a device that will give a voltage out proportional to the input regardless of load and with a constant time delay. Something like that?
I am having problems understanding where your misunderstanding lies.
The amplifier has to cope with reactive loads,if it cannot the problem is with the amplifier.
See above.
Not the same as the speaker impedance though. Do you know why tube amplifiers sound quite good?
No, it doesn't have to. It need only cope with a highly reactive load if you pick a speaker with a highly reactive impedance and phase angle. Why buy such speakers when you don't have to and there are more than a sufficient number of decent sounding speakers that do not require amplifiers capable of arc welding?
I once again repeat, "Only when amplifiers are asked to perform Herculean tasks does either amperage or output impedance become relevant. Therefore, the real question I find myself asking would be; why are we expecting amplifiers to perform Herculean tasks?"
This way of thinking is in line with Jim Theil's belief that "watts is cheap". And his speakers require lots of watts.
Russ, I believe this is my stop and I really don't wish to get on that bus with you.
What I find completely amazing is that John Atkinson has the ability to read this thread and know better than to get involved. Must be difficult to refrain from trying to help out.
Why do you say that? What sort of help do you suppose he might provide? I've agreed that lower output impedance is of value when the amplifier is faced with a difficult load. I don't know why everyone keeps repeating this as if I'm objecting to that fact. I have not agreed that more power is the arbitter of good sound. I have stated an amplifier need not face a difficult load to produce good sound.
Can we all not agree that the more "amps" an amplifier produces is by itself no indicator of a better sounding system? That is the original question of the thread. How we got into this prolonged discussion of output impedance is a bit beyond me.
Jan, you sound a bit agitated. Of course we can agree that the amount of amps produced is not the measure of it's quality. We all know it's watts that determines quality.
Just messing with you.
What is there in life that can be quantified by just one quality? Amplifier watts, Camera mega pixels, TV resolution, vehicle HP, computer CPU speed? So many of todays products are marketed on just one specification without taking into account the integration of the complete system.
I admit to being confounded as to why this has taken nine pages to get to this point.
WATTS is the starting point, if i know i want to have some realistic live sound, I don't even look at or consider a measly 100W or so pc. Watts matter. There is no hi fi without them. A better amplifeir with plenty of output devices, puts out lotsa current into any load, it really is that easy. And it can maintain teh voltage across the speaker in order for it to deliver teh current called for...then those 2 give ya WATTS, it matters. There is no hi fi, without watts, good clean, fast, stable, well heat sinked, so teh amp doesn't crap out. audio amplifier is a power supply, so the one with teh larger AC mains transformer is also the better ampliferi, sometimes simple electrical concepts are teh correct ones. Speed, current, low distortion, stabilty, and super freq response, mine run something like 10-500Khz freq response, it matters, just like super fast slew rates....the sound is not in teh finely crafted front panels with fancy engraved markings, or viewing windows to look at glowing tubes, that's all crap, and is a nice show, but when ya listen to the music, I ain't looking at teh front panels of teh amplifiers.....maybe if ya can't build great amps, just build nice covers for them, someone will buy em. Yeah, a window to view teh tubes, ain't that special, that's as dopey as the tube CD players with teh window to see a tube glowing, what an audiophile won't fall for.
Well why didn't you say that in the first place?
The difference between and median is that median is the halfway point between the minimum and maximum. The mean is the average, which takes into account the duration of levels.
uh-huh, that's what I thought. But that doesn't indicate 70% dropped to 3 Ohms. Or have I misunderstood again? I just don't see 70% of the speakers dropping beneath 3 Ohms in that graph or the text indicating such a situation.
I think that would be the case for any of those whom have gone through years of formal scientific training.
Science is a land of discovery -- there are no authorities in science - some people are open to learning from others and others have this notion they are a full authrority in something that (especially in the case of of Hi-Fi) requires many disciplines to come together to bring what they have learned forward - at the same time learn from the other disciplines in the field.
Some threads turn into "I can pee higher than you" contests and there is no need.
Quote.... "Science warns me to be careful how I adopt a view which jumps with my preconceptions, and to require stronger evidence for such belief than for one to which I was previously hostile. My business is to teach my aspirations to conform themselves to fact, not to try and make facts harmonize with my aspirations." T.H. Huxley
Wasn't the guys Watt and Ampere scientists, who said, this is how it is, after seeing Voltaire.....if these 3 dudes didn't stick to their ideas, we might be discussing the effects of not enough (what) watt?
Arc welding is an exaggeration and a big one.
You make designing an amplifier to cope with a complex load sound as difficult as a moon shot, it isn
You apparently have not been around this hobby for long. Dig up some reviews of the original Apogee Scintilla and read about the amplifiers used with that beast. Or the Infinity's of the same time period. There was a time when audiophiles did some very stupid things. (That should get a response!) And it seems speaker designers never talk to amplifier designers and vice versa.
Monotech - from the UK -- could deliver enough to weld steel - we tested them in 1989 - my god, they were well made. - Great as PA amplifiers with a relaibility NASA could only dream of. We deployed a lot of these into Mediteranean and Saudi climates (Hotels - Night clubs - Rock venues) and non failed.
It's not audiophile if it doesn't have limits, persnickerty faults, incapable of being reliable, drive anything it's hooked to. Be super reliable, and sound great. With SPECS that prove it's superiority. And have most of it's price inside, in components, and LARGE AC main transformer....not in some chassis that costs more than the parts inside. And never let it be able to be used in a commercial enviorment, with super reliablity, that somehow makes it non hi fi super grade audiophile. Again, since an amplifier is a modulated power supply, it has to deliver power, with is current and voltages at any load, that's the sign of a great design. If you "tweak" some gear with a magic connector, and all of a sudden the sound is more spacious, open, detailed, it either had poor connections,corroded bad solder joints, or you had too much vodka. High end sound, isn't mystical, just great electrical design and packaged in a proper case. Why do i want to look inside an etched glass window at some tubes glowing? How is that high end SOUND? That's stuff for Better Homes and Gardens, Or house Beautiful. Back to the SOUND, Back to electrical electronic design. Years ago SoundCraftsmen made amplifeirs that would be tested into direct shorts, several times, to prove it's superior ckts, they would shut down, then resume operation, with no damage. They didn't cost ten$ of thou$and$ of dollars either, they delivered several hundred watts into any load you hooked it to. so much great stuff available, and also so much hyped nonsense, are StereoPhile readers buying art work, or sound? I think it's drifted into buying art, not audio.
Was there not a manufacturer who demonstrated the stoutness of their high end power amplifier by running it into a dead short? I seem to remember the light show from the demonstration being the talk of a C.E.S. Not exactly arc welding but not far from it.
Seems the demonstartion I was referring to has been more recent than Soundcraftsman days.
Where did Soundcraftsman end up after its brief but unpromising engagement in high end audio? Pro sound. And not for its arc welding capabilites. It was never a top notch consumer amplifier, it just held together better than a Phase Linear - which ain't saying much. This is kinda like designing a car that can withstand a 50 M.P.H. crash rather than designing a car that can avoid a 50 m.p.h. collision.
Speaking of such, dup, do you work a second job as a crash test dummy? Sounds like the sort of thing you'd enjoy.
http://cgi.ebay.com/SOUNDCRAFTSMEN-RA-75...1QQcmdZViewItem
Unfortunately, it's not working today. Guess that dead short demonstration finally caught up with them.
Oh what a blast from the past!
Proof that SoundCraftsman did for a short time exist in the HiFi realm.
My old SC pre-receiver, now in need of a CraigsList posting along with some V nice (NOT)
yupper, when those 30 year old amplifers give up, it's a sure sign they musta been no good. Too bad my friend has one and teh pre amp equalizer and tehy both function flawlessly, the one that was the littel cube BEFORE Carver decided to take the idea and market it, it had a triac control, the thing was small, could put out like 200 hundred watts p/c down to.....under 2 ohms, again, well made, delivers the current needed, a stack of em could deliver some power, 200W per channel in a box less than 12 inches by 12 inches, no fancy chassis, it just worked well....not enough power for my needs though, but certainly better than some 35W.
I like the "liquid cooled" stickers on the speakers. It's true, but it would have never occurred to me to market them this way.
Multi way speakers are the way to go. No single driver is capable of doing it all, impossible, unless you are talking bout' a clock radio, or carradio, not realistic reproduction. Active crossovers for residential use is unnecessary. Active crossovers are used in large commercial enviorments, when multiple speakers are placed about a large area, where drastic room response differences are encountered. And the only way to get it together is to tune each cabinet to the room response with electronics. Checkout some large pro installations.
Pages