Quality Power - Page 13 - AVS | Home Theater Discussions And Reviews
Forum Jump: 
 
Thread Tools
Old 02-11-2014, 05:53 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
If I take a big solid-state amp with huge current reserves, then it would have more potential power available compared to a dinky receiver. Whether the reserve is ever used is another story, but it has more potential power available.

So my way of thinking was that at some point, the weaker amp would deliver the same current up until the point of clipping. From that point onwards, things change and the bigger amp picks up steam, as it were.

You are saying it's a function of the load, but if the amp doesn't have the extra current capability then it can't supply it no matter what. So in those extreme conditions, the larger amp can pull ahead and the weaker amp probably will be driven into extreme clipping. Note, I'm talking atypical conditions.

I'm just thinking out aloud here.
Heinrich S is offline  
Sponsored Links
Advertisement
 
Old 02-11-2014, 06:14 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,530
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1205
Quote:
Originally Posted by Heinrich S View Post

If I take a big solid-state amp with huge current reserves, then it would have more potential power available compared to a dinky receiver. Whether the reserve is ever used is another story, but it has more potential power available.

True, except that most amps don't clip because they run out of current, they clip because they run out of voltage.
Quote:
So my way of thinking was that at some point, the weaker amp would deliver the same current up until the point of clipping.

True, the point of clipping of the weaker amplifier.
Quote:
From that point onwards, things change and the bigger amp picks up steam, as it were.

True, as it were.
Quote:
You are saying it's a function of the load,

I'm saying that the relationship between current through the load and voltage across the load are established and controlled by the load.
Quote:
but if the amp doesn't have the extra current capability then it can't supply it no matter what.

If a source of the desired amount of current can't be found, then the voltage across the load and the current through the load is limited by that fact.

If a source of the desired amount of voltage can't be found, then the voltage across the load and the current through the load is limited by that fact.
Quote:
So in those extreme conditions, the larger amp can pull ahead and the weaker amp probably will be driven into extreme clipping. Note, I'm talking atypical conditions.

Under typical conditions, amps typically clip because they run out of their supply of voltage. This apparent obsession with current is audiophile myth.
Quote:
I'm just thinking out aloud here.

I'm trying to keep it real. ;-)
arnyk is offline  
Old 02-11-2014, 09:07 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Arnyk, why is voltage the reason why amps clip? If the load impedance has dips that are problematic and the amp can't supply the necessary current, then what would happen? You are saying the amp wouldn't clip? Only due to insufficient voltage?

I thought current and voltage was the limiting factor.
Heinrich S is offline  
Old 02-11-2014, 09:42 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,530
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1205
Quote:
Originally Posted by Heinrich S View Post

Arnyk, why is voltage the reason why amps clip?

I don't know for sure, but designing amps so that their limit is set by power supply voltages seems to make nice, reliable amplifiers.
Quote:
If the load impedance has dips that are problematic

if...

In reality, not so much.
Quote:
and the amp can't supply the necessary current, then what would happen?

if...

In reality, not so much.

If a too much current gets drawn, the power supply voltage decreases under load and bingo - the power amp is power supply voltage limited.

Quote:
You are saying the amp wouldn't clip?

Not at all, but there is this very common chain of events.
Quote:
Only due to insufficient voltage?

How the power supply voltage becomes insufficient varies, but in the end most amps clip while voltage-limited.
Quote:
I thought current and voltage was the limiting factor.

The excess current demand has consequences, but the usual consequences are that the power supply voltage drops and the amp runs out of voltage.

IME amps clip most cleanly if they clip due to insufficient power supply voltage to meet the demand. Current limiting can have nastier audible consequences than hitting a voltage limit.
arnyk is offline  
Old 02-11-2014, 11:39 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
Originally Posted by arnyk 
Current limiting can have nastier audible consequences than hitting a voltage limit.

How would it be worse than voltage limiting? If an amp clips ... as you say due to insufficient voltage, then the effects would be rather obvious, would they not? How would one know if their amp was clipping due to insufficient current, or insufficient voltage? Or does it not matter?

If the effects of current limiting can have worse side-effects, what kind of side-effects would one experience? I've experienced clipping in my system and it sounds terrible. Perhaps what I experienced was current limiting. Not sure.
Heinrich S is offline  
Old 02-11-2014, 12:11 PM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,530
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1205
Quote:
Originally Posted by Heinrich S View Post

Quote:
Originally Posted by arnyk 
Current limiting can have nastier audible consequences than hitting a voltage limit.

How would it be worse than voltage limiting?

In an electrical circuit you can constrain or limit only one parameter at a time, either current or voltage.

If you constrain the voltage then the voltage is cleanly clipped, but the current can vary as it will.

If you constrain the current then the current is cleanly clipped, but the voltage can vary as it will.

Clean clipping is relatively sonically innocuous especially if mild and/or infrequent.
Quote:
If an amp clips ... as you say due to insufficient voltage, then the effects would be rather obvious, would they not?

Well, they are as obvious as the severity of the clipping is.
Quote:
How would one know if their amp was clipping due to insufficient current, or insufficient voltage?

People use oscilloscopes to observe such things.
Quote:
Or does it not matter?

It matters more the more extensive it is.
Quote:
If the effects of current limiting can have worse side-effects, what kind of side-effects would one experience?

Harsher sounds given the amount of clipping.
Quote:
I've experienced clipping in my system and it sounds terrible.

Probably pretty severe clipping. Please post an oscilliscope trace of the clipped waveform and we can talk.
Quote:
Perhaps what I experienced was current limiting. Not sure.

Hey, from thousands of miles away I'm supposed to give a definitive answer? ;-)
arnyk is offline  
Old 02-11-2014, 12:47 PM
AVS Special Member
 
DonH50's Avatar
 
Join Date: Feb 2010
Location: Monument CO
Posts: 6,492
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 323 Post(s)
Liked: 326
Most amplifiers are designed to be good voltage sources. Current clipping is more rare because amplifiers can usually supply a goodly amount of current for short periods, whilst over driving the voltage rail causes instant clipping. Feedback is usually voltage-based but any sort of clipping can wreak havoc with the feedback circuit and cause unstable operation, from ringing to oscillation to large output glitches. Note speakers can also be over driven. I (and Arny, and many others) have heard when that happens and it is not pretty.

Heinrich S, you'd be way ahead to take a basic electronics course at a local junior college or trade school, or even online. A lot of the concepts you are interested in and yet struggling with are hard to convey via the Internet. In person is much easier, especially with a drawing board or pad at hand. You have the interest, why not take the next step? A basic class won't get into amplifier classes and transistor thermal modulation, but will provide the context for a better understanding of them.

You could also look up some basic concepts on Wikipedia. And, there are a bunch of introductory electronics threads compiled over on the What's Best Forum that might help a little.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
DonH50 is online now  
Old 02-11-2014, 01:10 PM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
Current clipping is more rare because amplifiers can usually supply a goodly amount of current for short periods, whilst over driving the voltage rail causes instant clipping.

I never knew that an amp could clip due to voltage limitations only and also current limitations only. I thought current and voltage were intertwined. I thought the lack of power caused the clipping, and power is voltage x current.
Quote:
You could also look up some basic concepts on Wikipedia. And, there are a bunch of introductory electronics threads compiled over on the What's Best Forum that might help a little.

Probably would be a good idea. smile.gif Thanks.
Heinrich S is offline  
Old 02-11-2014, 01:11 PM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
Originally Posted by arnyk 
Probably pretty severe clipping. Please post an oscilliscope trace of the clipped waveform and we can talk.

Have no idea what you are talking about. I've never used an oscilliscope and wouldn't know how to interpret the results even if I did. Please remember you're talking to a layman here. smile.gif
Heinrich S is offline  
Old 02-11-2014, 02:27 PM
AVS Special Member
 
DonH50's Avatar
 
Join Date: Feb 2010
Location: Monument CO
Posts: 6,492
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 323 Post(s)
Liked: 326
Power is voltage times current, which means either voltage or current (or both) could clip. Without measuring or analyzing it may be hard to tell which. You could design an amp that puts out gobs of current but has very low voltage rails and thus voltage would be clipping all the time. Similarly you could design an amp with very high voltage rails but little current ability and current would clip most of the time. In the real world most audio amps fit the voltage-amp model though current clipping can and does occur, natch. However, IME, voltage clipping is the dominant factor for audio amps.

It's actually oscilloscope and it is used to view time-varying waveforms, sort of a picture of the signal in real time. http://en.wikipedia.org/wiki/Oscilloscope

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
DonH50 is online now  
Old 02-11-2014, 10:10 PM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
Originally Posted by DonH50 
You could design an amp that puts out gobs of current but has very low voltage rails and thus voltage would be clipping all the time. Similarly you could design an amp with very high voltage rails but little current ability and current would clip most of the time

I'm sure I asked the question a few pages back how an amp can have high voltage but low current. You guys said it can't happen. High voltage means high current. You guys said you can't have an amp with low current and high voltage. This is very confusing. frown.gif I even provided examples of big power supplies, and you guys kept saying how the puny receivers could supply the same current and voltage up until clipping.

So which is it? You can have an amp with high voltage and low current (the Yamaha was the example I brought up and it was shot down) or not?
Heinrich S is offline  
Old 02-12-2014, 04:54 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,530
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1205
Quote:
Originally Posted by Heinrich S View Post

Quote:
Originally Posted by DonH50 
You could design an amp that puts out gobs of current but has very low voltage rails and thus voltage would be clipping all the time. Similarly you could design an amp with very high voltage rails but little current ability and current would clip most of the time

I'm sure I asked the question a few pages back how an amp can have high voltage but low current. You guys said it can't happen. High voltage means high current. You guys said you can't have an amp with low current and high voltage. This is very confusing. frown.gif I even provided examples of big power supplies, and you guys kept saying how the puny receivers could supply the same current and voltage up until clipping.

So which is it? You can have an amp with high voltage and low current (the Yamaha was the example I brought up and it was shot down) or not?

A little hygienic thinking is required. The discussion varies depending on whether we are talking about sources (amplifiers) or loads (speakers). Amplifiers are the servants of loudspeakers.

A loudspeaker that takes high voltage and then passes only low current is known as a high impedance speaker.

A loudspeaker that takes low voltage and then passes high current is known as a low impedance speaker.
arnyk is offline  
Old 02-12-2014, 07:24 AM
AVS Special Member
 
DonH50's Avatar
 
Join Date: Feb 2010
Location: Monument CO
Posts: 6,492
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 323 Post(s)
Liked: 326
+1. You are confusing the source (amplifier) and load (speaker). An amp can have high voltage rails, low voltage rails, high current capacity or low, but the speaker (and volume) dictates what it actually needs to deliver at the output.

Your wall outlet can deliver about 1800 W but if you only plug in a 100 W light bulb it will only deliver 100 W. If you plug in a 5000 W bulb it will "clip".

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
DonH50 is online now  
Old 02-12-2014, 08:40 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
A loudspeaker that takes high voltage and then passes only low current is known as a high impedance speaker.

A loudspeaker that takes low voltage and then passes high current is known as a low impedance speaker.

But this is what I'm confused about. How can current be high at a low voltage? You guys knocked it inside my head that high current can only result from high voltage.

So then correct me if I'm wrong, but source load-wise, you can't have a high current from a low voltage. But a speaker could demand a higher current than another speaker with less voltage applied?

See, I understand that. I know some speakers are difficult to drive. But even then, if you have a low voltage applied, you can't have lots of current. The current will be determined by the load impedance and the voltage applied. If you lower the voltage, current has to go down.

Am I wrong?
Heinrich S is offline  
Old 02-12-2014, 08:50 AM
AVS Special Member
 
David James's Avatar
 
Join Date: Dec 2000
Location: Longmont, CO
Posts: 1,947
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Liked: 76
Quote:
Originally Posted by Heinrich S View Post

But this is what I'm confused about. How can current be high at a low voltage? You guys knocked it inside my head that high current can only result from high voltage.
This is an audio / visual forum not an EE forum. The people here have been kind (and incredibly patient) trying to help you understand amp concepts. They are answering the same questions, asked a million different ways, over and over again. You don't understand. Don't take that as criticism, it's the fact that the underlying concepts are complicated and require basic knowledge which you don't have. It's been suggested you take some classes, I urge you to consider that suggestion.
David James is offline  
Old 02-12-2014, 08:52 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
But I understood things just fine earlier on in this discussion. Surely there must be a simple explanation why I am not understanding this.

Instead of telling me to go for lessons, why not explain it? If you don't want to, then why are you posting here?

This is what pisses me off. I make an effort to understand a concept. Based on what people have told me. Now people are telling me the opposite of what they told me and now I must go for lessons. frown.gif It's unbelievable.
Heinrich S is offline  
Old 02-12-2014, 08:55 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Quote:
Originally Posted by David James View Post

This is an audio / visual forum not an EE forum. The people here have been kind (and incredibly patient) trying to help you understand amp concepts. They are answering the same questions, asked a million different ways, over and over again. You don't understand. Don't take that as criticism, it's the fact that the underlying concepts are complicated and require basic knowledge which you don't have. It's been suggested you take some classes, I urge you to consider that suggestion.

I don't need to be patronised. It was said again and again that you CANNOT have a high current with a low voltage. How many examples of amplifiers did I bring up and how many times did people tell me, over and over again?

So instead of patronising me, if you had the technical chops to explain it in a way that can be undertood, then do it. Don't patronise me, tell me to go for lessons, and then keep your mouth shut. Rather don't say anything at all and don't post in this thread.
Heinrich S is offline  
Old 02-12-2014, 09:04 AM
 
SAM64's Avatar
 
Join Date: Apr 2011
Posts: 1,592
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 74
Quote:
Surely there must be a simple explanation why I am not understanding this.

You don't understand Ohms law. Look at the equation:

V = IR, rearrange it, plug numbers into it and play with it. Once you understand this equation and what it means you'll be ahead.
Quote:
High voltage means high current.

In the real world, power supplies have a source impedance, this limits the amount of current they can supply.

Using 0 as a load resistance a power supply would have to supply infinite current, plug those numbers into the power equation, you'd have a supply of infinite power....all the worlds energy problems would be solved. This is not reality.
Quote:
So instead of patronising me, if you had the technical chops to explain it in a way that can be undertood, then do it.

Wow, maybe you need to study simple algebra again.
SAM64 is offline  
Old 02-12-2014, 09:11 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Okay, so basically this entire thread has been a major waste of time for me. So a high current can result from a low voltage. Basically contradicts everything that was said earlier.

Great. Thanks for the amazing advice! rolleyes.gif
Heinrich S is offline  
Old 02-12-2014, 09:16 AM
 
SAM64's Avatar
 
Join Date: Apr 2011
Posts: 1,592
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 74
Quote:
So a high current can result from a low voltage.

Of course, it depends on the load.

Ohms law clearly states this.

Quote:
Basically contradicts everything that was said earlier.

there's no contradiction.
SAM64 is offline  
Old 02-12-2014, 09:22 AM
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 14,530
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 851 Post(s)
Liked: 1205
Quote:
Originally Posted by Heinrich S View Post

Quote:
A loudspeaker that takes high voltage and then passes only low current is known as a high impedance speaker.

A loudspeaker that takes low voltage and then passes high current is known as a low impedance speaker.

But this is what I'm confused about. How can current be high at a low voltage?

Asked and answered - the speaker would have to have a very low impedance.
Quote:
You guys knocked it inside my head that high current can only result from high voltage.

I suspect that you did that to yourself, Heinrich! ;-)
Quote:
So then correct me if I'm wrong, but source load-wise, you can't have a high current from a low voltage.

You can, if the impedance is low enough.
Quote:
But a speaker could demand a higher current than another speaker with less voltage applied?

yes, a speaker with a very low impedance.

Quote:
See, I understand that. I know some speakers are difficult to drive. But even then, if you have a low voltage applied, you can't have lots of current. The current will be determined by the load impedance and the voltage applied. If you lower the voltage, current has to go down.

no, you're right (finally!).\


But Heinrich, please let me be the 47th (more or less) guy to accuse you of trying to learn everything an EE knows by asking one question at a time on AVS...

You have already been referred to some good free online EE courses. Hint! Hint! Nudge! Nudge!
arnyk is offline  
Old 02-12-2014, 09:30 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Okay, so amps can't supply lots of voltage with a low current or lots of current at a low voltage. Hence the monster amp examples I brought up earlier ... the big supplies can't deliver high current at a low voltage, which is what you guys beat me over the head with.

But the speaker can demand more current if the impedance is low enough .. and another speaker may require more voltage, but may not demand as much current from the amplifier due to the load impedance. This is what you were discussing about the load impedance requiring less voltage for a given current or more current for a voltage.

If I understand that correctly, and this this thread is about amplifiers and power, then what exactly did I misunderstand???
Heinrich S is offline  
Old 02-12-2014, 10:11 AM
AVS Addicted Member
 
Ratman's Avatar
 
Join Date: May 2002
Location: Collingswood, N.J.
Posts: 14,805
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 288 Post(s)
Liked: 334
Maybe it's not what you misunderstand, it's more that you are looking to learn "stuff" one post at a time. Every question that's answered, generates two more. Nothing wrong with that... but, it's really become annoying. Especially when one or two others add their comments/opinions which distracts from the dialog due to a difference of opinion.

Seriously... take some "formal" classes as opposed to abusing the generosity of a few participants. They may have paid for their education and/or had field experience for many years.
Perhaps you can arrange a tutorial agreement with a willing individual to provide private/personal education offline.
Ratman is online now  
Old 02-12-2014, 10:11 AM
AVS Addicted Member
 
amirm's Avatar
 
Join Date: Jan 2002
Location: Washington State
Posts: 18,504
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1081 Post(s)
Liked: 571
Quote:
Originally Posted by Heinrich S View Post

But this is what I'm confused about. How can current be high at a low voltage? You guys knocked it inside my head that high current can only result from high voltage.

So then correct me if I'm wrong, but source load-wise, you can't have a high current from a low voltage. But a speaker could demand a higher current than another speaker with less voltage applied?
I think part of the problem is that the folks that are answering you, also have a point of view here and are careful to keep you from going there smile.gif. Since I post with reckless abandon biggrin.gif, let me explain this a different way.

A speaker has both inductive and capacitive elements in it. As soon as you have these, the current and voltage waveforms no longer match. This is a hard concept to understand but it is how the system works. What this means is that you can throw out any explanation of this question that uses resistive loads such as "8 ohms" and such. No speaker acts like that. This is why we use the term "impedance" as opposed to resistance with the former having inductive/capacitive characteristics.

In such loads, the peak current and voltage requirements occur at different points in time. Here is an extreme example where they are 90 degrees "out of phase" which is a fancy way of saying there is a time delay between current and voltage:

polarity_phase_07.gif

Look at the "360" degree mark. At that point if we assume the red is the current, it is at maximum. Now let's assume the blue is the voltage. Note that it is at zero. Yes, zero! Dead short. At this frequency and in this situation, the speaker presents a dead short but yet, demands lots of current.

This presents a problem beyond what the power supply can generate. The output transistors do not like to be shorted out like this. Most amplifiers have a protection circuit that attempts to protect the output transistors by limiting the amplifier output. The amount of current provided may be very little in this case. Some will also shut down completely. A much beefier amplifier not only has better power supply but also many output transistors in parallel. Well designed ones can sit there with such a "dead short" and put out 10 amp or more all the day long. They may not even have to have any protection circuit as the output stage can withstand all the current the power supply provides without being damaged.

If the smaller amp does not go into protection, it will modulate its output on every transient in this frequency. Such "pumping" of the output is not the classical voltage clipping by a dynamic situation where nonlinearities are generated.

So we have two extremes of this situation:

1. Resistive load. No speaker is purely resistive yet almost all the amplifier power testing is done with "dummy loads" which are resistive. This means that the amplifier tests by magazines and such in this regard is the easiest test case, not typical or worst!

2. The 90 degree out of phase example. This is again is an extreme situation and one that is not likely to occur in speakers.

The speaker you own lands somewhere in between these two extremes. Where? You don't know unless you have its measurements. WIthout measurements you are in the dark and can never perform this analysis. What to do? Simple: buy the most powerful amplifier you can buy. The more powerful the amplifier, the less it is impacted by the "difficult loads." Companies building active speakers know the load perfectly and therefore tailor the amplification to that. For the rest of the systems with passive speakers, it is a guessing game.

Since amplifiers do not become obsolete like the rest of the system components, it pays to buy high quality and buy it once. My workhorse amp is a proceed 5 channel amplifier. I have had it more than a decade with never a need to get something better. It has 5 separate amplifiers in the box and weighs something like 120 pounds! I never have to worry about it being the cause of distortion. Of course as powerful as it is, it is not a fit for driving subwoofers and such.
Quote:
See, I understand that. I know some speakers are difficult to drive. But even then, if you have a low voltage applied, you can't have lots of current. The current will be determined by the load impedance and the voltage applied. If you lower the voltage, current has to go down.

Am I wrong?
The "difficult to drive" speaker is one that has its current and voltage out of phase the most when its impedance is also the lowest. That is the worst of both worlds. These speakers demand the highest power and most robust amplification you can throw at them. But again, without measurement you don't know if yours is such and hence my advice is to buy the beefiest amp you can and be done with it.

Edit: fixed a typo and formatting.

Amir
Retired Technology Insider
Founder, Madrona Digital
"Insist on Quality Engineering"
amirm is offline  
Old 02-12-2014, 10:21 AM
AVS Addicted Member
 
amirm's Avatar
 
Join Date: Jan 2002
Location: Washington State
Posts: 18,504
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 1081 Post(s)
Liked: 571
Quote:
Originally Posted by Ratman View Post

Maybe it's not what you misunderstand, it's more that you are looking to learn "stuff" one post at a time. Every question that's answered, generates two more. Nothing wrong with that... but, it's really become annoying. Especially when one or two others add their comments/opinions which distracts from the dialog due to a difference of opinion.
People who are annoyed don't need to read or answer his posts. The fact that they continue to do so means they see some interest in going on.
Quote:
Seriously... take some "formal" classes as opposed to abusing the generosity of a few participants. They may have paid for their education and/or had field experience for many years.
Perhaps you can arrange a tutorial agreement with a willing individual to provide private/personal education offline.
Let's not go there please. If we are claiming to be able to explain things and then fail, then the problem is here. I have read the all the answers but they do provide a confusing picture to anyone reading it. And miss some important details like what I just explained.

Amir
Retired Technology Insider
Founder, Madrona Digital
"Insist on Quality Engineering"
amirm is offline  
Old 02-12-2014, 10:38 AM
AVS Special Member
 
JHAz's Avatar
 
Join Date: Mar 2009
Posts: 4,099
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 143 Post(s)
Liked: 173
Quote:
Originally Posted by Heinrich S View Post

Okay, so basically this entire thread has been a major waste of time for me. So a high current can result from a low voltage. Basically contradicts everything that was said earlier.

Great. Thanks for the amazing advice! rolleyes.gif

let me suggest that you go here http://www.ohmslawcalculator.com/ohms_law_calculator.php and play with numbers. Enter any two of power, current, resistance, voltage and it will tell you what the other numbers must be according to ohm's law. So you could, for example, start with 10 volts and see how the current changes when you go from say 1,000,000 ohms (a not uncommon input impedance for an amp) to 8 ohms to 4 ohms etc.

You could also ask yourself, "I wonder what the volts and amps (voltage and current) look like at 100 watts into an 8 ohm load versus a 4 ohm load versus whatever other load attracts your interest. Plug in 100 watts power, plug in the appropriate resistance, and voila, you get volts and amps. The answers have to be true because they are calculated based on a law of our physical universe.

It's really hard to think about this stuff entirely in the abstract. Look at how some numbers work in the calculator and it may start to make sense. I'd do it for you but at least for ome things don't stick in my head nearly as well unless I do the work myself.

addendum:

Just to put things together for you. Power is bu definition volts times amps. You have to know voltage and amps (current) to caclulate power. 1 volt at 10 amps is 10 watts. 100 volts at one tenth of an amp is 10 watts. four volts at 2.5 amps is 10 watts.

Voltage and amps (identified as "I" in classic electronics equations) are proportional, depending on the resistance (in ohms). Amps equals volts divided by resistance. Every millisecond of every day in every electrical circuit in our universe, volts are equal to amps divided by ohms. So if you know amps and ohms you can calculate amps (one amp through one ohm requires one volt. two amps through one ohm requires two volts, etc). The rest is really basic algebra. AC circuits complicate things because the resistance component may vary with frequency, but for purposes of understanding at least basically how it works, this is all you need.
JHAz is offline  
Old 02-12-2014, 10:59 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
I messed around with the calculator. I took 40 volts x 50 amps and I get 200 watts into an 8 ohm load. 400 watts into a 4 ohm load.

I just want to make 100% sure that I know that amps, and I'm sure you helped me understand this before, can't deliver high current at a low voltage. If the voltage is low, then current can't be high - the amp can't put out lots of amperage. My understanding is that in order for current supply to be high, the voltage and resistance would need to change, hence the load impedance and voltage determine the current drawn. Increase the voltage, you increase the amount of current drawn.

Therefore, huge amps can't push lots of current at low volumes. A Krell monster amp can't deliver more current than an cheap Dixon if the voltage applied does not exceed it's output capabilities.
Heinrich S is offline  
Old 02-12-2014, 11:13 AM
AVS Special Member
 
A9X-308's Avatar
 
Join Date: Mar 2008
Location: Australia; now run by adults.
Posts: 5,543
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 214 Post(s)
Liked: 132
Quote:
Originally Posted by Heinrich S View Post

I messed around with the calculator. I took 40 volts x 50 amps and I get 200 watts into an 8 ohm load
No. 40x50 = 2000. 40V into 8R is 200W, but it won't be 50A, rather 5A.
A9X-308 is offline  
Old 02-12-2014, 11:20 AM
 
Heinrich S's Avatar
 
Join Date: Aug 2007
Posts: 974
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 30
Sorry, I meant to say 5 amps, not 50 amps.
Heinrich S is offline  
Old 02-12-2014, 12:16 PM
Super Moderator
 
markrubin's Avatar
 
Join Date: May 2001
Location: Jersey Shore
Posts: 23,281
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 181 Post(s)
Liked: 588
lots of reports received: please be kind smile.gif

please take the high road in every post
if you see a problematic post, please do not quote it or respond to it: report it to the mods to handle
markrubin is offline  
 
Thread Tools


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off