High current design?

[nahmed]

What does it mean when an amplifier has a "high current design"?

If it can drive 4 ohm speakers, does this capability let it drive 8 ohm speakers better than an amp that can only drive 8 ohm speakers?

thanks
Nadeem

[RGA]

ignore High current. It's advertising gimmickery - there are some terrific amplifiers which in the strictest sense are not high current amplifiers. Maybe the best sub 2k integrated amplifier the Sugden A21a is not a high current amplifier. The idea behind it is that if an amplifier is rated 100 watts at 8 ohms then it will muster 200 watts at 4ohms and 400 watts at 2 ohms 800 watts at 1 ohm etc(well this never actually happens). Speakers have impedence swings which range anywhere from 2-30ohms depending on speakers. The marketers love this because they can say see our amplifier can handle those momentary spikes (usually in the lower and higher frequencies) where a speaker may DIP to 3ohms. Most all amps are capable of momentary power. The Sugden is a pure class A design and is 25 watts into 8 ohms and LESS into 4ohms. Certain BADLY DESIGNED loudspeakers will not like the A21a - I suppose.

If you're looking at receivers just ignore it completely. Sales staff would love to upsell a reciever because of supposed "high current."

[kexodusc]

Maybe I'm way off, but I seem to remember a time when manufacturers often posted specs including the amount of amperes that the amplifier would deliver (ie: 20, 28, 30, 35 40 amperes). The higher that number the higher the current? Could this be what it means?
Now, at a given voltage and a nominal resistance in a system, wouldn't this have some impact on the signal reaching the speakers?

[Geoffcin]

What does it mean when an amplifier has a "high current design"?

If it can drive 4 ohm speakers, does this capability let it drive 8 ohm speakers better than an amp that can only drive 8 ohm speakers?

thanks
Nadeem

High current amps are designed to deliver the correct current into low impedance loads. Some of the very best ones are not bothered by loads approching 1ohm. These amps are not just for difficult to drive speakers, but can make ANY speaker sound better as no speaker has a uniform impedance. A high current design will deliver the proper current no matter what the load.

[Pat D]

What does it mean when an amplifier has a "high current design"?

If it can drive 4 ohm speakers, does this capability let it drive 8 ohm speakers better than an amp that can only drive 8 ohm speakers?

thanks
Nadeem First of all, lets get the matter of speaker impedances figured out. Speaker impedances almost always vary considerably with frequency. A number reviewers provide an impedance vs. frequency curve for the speakers they review. You can find them in Stereophile, Audio Ideas Guide, and Soundstage. It's easy to find illustrations of this on the Soundstage site, so I will provide a link:

http://www.soundstagemagazine.com/speakermeasurements/

You will find that many speakers with an 8 ohm rating actually get considerably lower than that. There are no standards for the impedance ratings of speakers that I know of. But, as it turns out, most receivers will still drive them at ordinary levels. Of course, if the protection circuitry cuts in or the amp gets too hot, then you have some cause to be concerned.

Those who say that "high current" is an advertising slogan are pretty well right, as there is no standard for what is meant. For most of us, an amplifier that can deliver a lot of power into 4 ohms would have a high enough current capability. However, some speaker have an impedance which gets fairly low in certain frequency ranges, some down close to 1 or 2 ohms. This to me is bad design, but many say some of those speakers sound very good. So, you need an amp with a pretty hefty power supply to drive them to a decent sound level.

Do super capable amps sound better with ordinary speakers? Not really. As long as you stay within the amp's capabilities, you should be fine.

Let us take some of the silliness that has been given here. Suppose you have an amp rated at 100 watts into 8 ohms and 200 watts into 4 ohms. In the US, if that is what is claimed, then the amp MUST meet those specs. Now lets take a 200 watt amp, rated into 8 ohms, which is rated at 300 watts into 4 ohms. Which is the more capable amp driving a 4 ohm load? Yet according to some here, that would not qualify as high current!

[Mr Peabody]

There are more benefits to high current design than just driving low impedances and it's not just marketing. I don't think Krell, Levinson, Bryston, Arcam amongst others who are high current and some of the finest amps made would agree either that "high current" is just marketing. The higher current allows better control of the driver, especially the woofer, and is better suited for handling quick transcients which equates to better dynamics. Sugden is more of a unique product and not the norm. In some receivers maybe there is some hype. I would use Onkyo as a reference, unless they have recently changed, I guarantee they are high current. Other than Sugden, I can't think of a high end amp that wouldn't be a high current design, just referring to solid state. Also, high current amps tend to have larger power supplies in them. All watts are not created equal.

Don't take my word, do some listening. I think you will find a high current amp will deliver a more powerful and dynamic presentation, much more punch in the bass. and will hold it's own against amps rated with twice the watts using the same speakers. A high current amp in comparison to other designs will sound like the loudness control is on. You will also notice that high current amps will maintain their sound quality better at lower volume.

It is also interesting that some of the finest sounding speakers in the world are very inefficient. So what does that say about your poorly designed speaker theory? Again, Audio Note is the minority and not the majority. Because they decide to do things differently can't make the other hundereds of engineers wrong.

[RGA]

What about tube amps? Are these high current?

Lately the best sound I've heard is from Tube amps - it's odd because Sugden is often linked to valve ability - and in other reviews strangely as a poor man's Krell - though Krell irritates me and Sugden doens't so that's odd.

I do agree though but Companies like Bryston don't advertise buzz words like High current - bbut Bryston makes awesom amplifiers with incredibly low noise floors and frankly I would not SPEND more on solid state power than a Bryston. Some would probably arguye you could spend less to get the ultimate SS sound - i suppose that's true but Bryston mixes the build sonics and warranty and customer service that IMO if it doesn't do it for you you should dump SS completely and go to some kind of tube amp.

Despite the technical and measurable flaws - they SOUND better when properly implemented - unfortunately one needs the money.

[Mr Peabody]

Maybe they call Sugden the poor man's Krell because you can get a pure Class A amplifier for $2k. I not sure what Krell's class A is running but it has to be several times that. I don't know why you like Bryston but not Krell, they are fairly similar, except krell is better. In my biased opinion.

I wish someone around here carried AN or Sugden. I'd love to hear them. You have to admit though they are both unique in the market. I don't understand why stores wouldn't jump on AN, an efficient speaker that actually sounds good. That would be a first for me.

[Beckman]

I would use Onkyo as a reference, unless they have recently changed, I guarantee they are high current.

Don't take my word, do some listening. I think you will find a high current amp will deliver a more powerful and dynamic presentation, much more punch in the bass. and will hold it's own against amps rated with twice the watts using the same speakers. A high current amp in comparison to other designs will sound like the loudness control is on. You will also notice that high current amps will maintain their sound quality better at lower volume.


What seperates a good amp from a bad amp is its ability to maintain the integrity of the signal with no regard to how much current is being drawn. This is not an easy task. As more current is drawn things heat up, the characteristics of the transistors change, and the power supply portion of the amplifier must regulate the voltage used to bias the transistors. Fluctuations in these bias volatges can increase distortion levels. This is why when you hook up a $130 Pioneer 100x2 reciever to a pair of speakers that can handle 400 Watts and turn the volume up all the way the music sounds terrible.

All this said, I wouldn't judge an amplifier on anything other than the quality of the sound it produces. Ratings don't mean much. Distortion levels are usualy given at 1 watt, power ratings are nonsense, as you have to increase the power 10 fold to double the dB's. Your best bet when purchasing an amp is to listen to as many as possible.

[Beckman]

Do super capable amps sound better with ordinary speakers? Not really. As long as you stay within the amp's capabilities, you should be fine.

Let us take some of the silliness that has been given here. Suppose you have an amp rated at 100 watts into 8 ohms and 200 watts into 4 ohms. In the US, if that is what is claimed, then the amp MUST meet those specs. Now lets take a 200 watt amp, rated into 8 ohms, which is rated at 300 watts into 4 ohms. Which is the more capable amp driving a 4 ohm load? Yet according to some here, that would not qualify as high current!

Some amps don't have hardly any capabilities, try turning a $100 reciever up half way with any speakers.


Let us take some of the silliness that has been given here. Suppose you have an amp rated at 100 watts into 8 ohms and 200 watts into 4 ohms. In the US, if that is what is claimed, then the amp MUST meet those specs. Now lets take a 200 watt amp, rated into 8 ohms, which is rated at 300 watts into 4 ohms. Which is the more capable amp driving a 4 ohm load? Yet according to some here, that would not qualify as high current!

Good point, I have found the high current term to be used in the mass market realm of things. I do think some Onkyo high current designs sound much better than there mass market equivalents (the TX-8511 also costs twice as much as some of the mass market equivalents). But for the most part I would trust the sound of the amp with my speakers over any buzz words (besides Warranty or return policy).

[skeptic]

There are many factors which determine the performance of an audio amplifier and it is not easy to characterize one versus another with a few simple numbers or buzz words. One of the factors which determines how satisfactory an amplifier will perform is the load it is connected to and how hard that load will be driven. While the term "high current" is a qualitative term, it is a fact that some amplifiers are deliberately designed to deliver more current and therefore more power to a load for at least a short period of time than other amplifiers having comparable nominal ratings. Will a 25000 horsepower Pratt and Whitney engine outperform a Volkswagon Beetle engine? Lifting an airplane into the sky yes. Driving to the corner grocery store, no.

Amplifiers designed for high current have at least a few differences from amplifiers which aren't. They have more robust power supplies and they have output devices, usually transistors, which can handle more current. This does not mean that these amplifiers have better regulated power supplies (where the dc output voltage doesn't change with changes to line voltage input) or that these amplifiers have lower distortion, less noise, or wider flatter frequency response. But when pushed to their limits, this type of amplifier won't exceed operation within its linear range as quickly as amplifiers of comparable power ratings which are not designed for high current. Whether or not this is of benefit to a consumer depends as I said on the rest of the equipment and how it is to be used.

[RGA]

Maybe they call Sugden the poor man's Krell because you can get a pure Class A amplifier for $2k. I not sure what Krell's class A is running but it has to be several times that. I don't know why you like Bryston but not Krell, they are fairly similar, except krell is better. In my biased opinion.

I wish someone around here carried AN or Sugden. I'd love to hear them. You have to admit though they are both unique in the market. I don't understand why stores wouldn't jump on AN, an efficient speaker that actually sounds good. That would be a first for me.

Give Audio Note some time - not everyone is allowed to carry Audio Note because it has to be sold on their terms - not very many dealers frankly can afford to carry them much less have a dedicated Audio Note room with all Audio Note gear...most places have mixed and matched set-ups...a MF amp witth a Rotel cd player and a Vanden Hul Cable and some B&W's conencted up with a linn Turntable. With Audio Note it has to be ALL Audio Note. The thinking behind it is - if you hate it at least they know they crashed and burned with THEIR equipment and not let down by someone elses crappy componant. It also means that if you LOVE what you hear you are more likely to buy all Audio Note. Few would but whatthe hell you get to hear all their stuff at once which at least gives them a shot to sell you a cd player with your speaker purchase etc. The other part of that though is that their amplifiers are relatively low powered - pretty powerful for SET but they need a certain type of speaker to play their best - their speakers are supposedly mirrorimaged to their amp - so they really don't want to see their 8 watter connected to a B&W. I don't know why not since the N805 sounded better to me with the Meishu than it ever did with Rotel or High power Classe separates. But generally many speakers need more than 8 watts per channel. IMO bad ones need more than 8 watts but I'm getting biased now.

There are 25 dealers in the US(I think 5 are in California though) - and my dealer may end up actually building the speakers to reduce prices of shipping from Europe - Another dealer is building the DACs. I have a feeling the dealers also have to have technical know-how to perform upgrades etc - and they need deep pockets to carry several mAudio Note models. The fact that the company doesn't waste money on advertising or product literature means that most people who buy it will be people going in and actually listening(shudder the thought) to it rather than being pre-sold by the marketing hype of magazines. So dealers are going to have to believe in it themselves because it is a risk to take up valuable sales space with a relatively ugly no name brand when you could carry Paradigm - which is a houshold name(Of course a place like Soundhounds carries both and B&W so they can stay in business selling that stuff but also carry the lesser known and IMO better sounding gear). So you're going to need a dealer who is passionate a bit about music themselves and are willing to sacrifice some volume sales.

Sugden unfortunately is just too small - and they have, at least for now, pulled out of North America. My dealer never sold much Sugden but after the high praise in Stereophile he has had many inquiries...but he can't get any. Typical - no one wanted it until the reviews. I wish people would actually LISTEN to stuff than buy out of magazines. LOW watt SS is a tough sell - The point of SS is to have high power with sacrificed sound otherwise you would buy low powered superior tube amps(as the marketing goes here). A low watt SS amp may be viewed as a curiosity - won't sell to the people wanting or needing high power SS and won't seel to tube lovers - because they want tubes. Well actually I should not say won't sell it's the longest selling commercial amp - but you are right it is an exception and an oddity. They don't advertise either - such products you seek out by listening.

Bryston to me is too close to Krell to warrant the extra money Krell charges. Even though Krell is class A it really doesn' do it for me - though you know I've only heard Krell once and it was with a relatively unfamiliar speaker to me in Hales - so perhaps I should give them another try. And of course many amplifiers are better suited to the need of the speakers.

[Beckman]

Here is another opinion I suggest reading:

http://forum.ecoustics.com/bbs/messages/1/6893.html

I don't know how reliable the source is, but it makes sense.

[mtrycraft]

Maybe I'm way off, but I seem to remember a time when manufacturers often posted specs including the amount of amperes that the amplifier would deliver (ie: 20, 28, 30, 35 40 amperes). The higher that number the higher the current? Could this be what it means?
Now, at a given voltage and a nominal resistance in a system, wouldn't this have some impact on the signal reaching the speakers?


Yes, NAD I think was/is one who uses these kind of ratings. But, to see if that is in fact is the case, ask yourself if the amp can deliver the power commensurate with their claims following Ohm's Law: Power = current squared times speaker resistance you are driving. Try it:) 20 squared is 400 watts by itself. Using 2 ohm speakers is 800 watts, 4 ohms 1600 watts. Sure those amps can do that, LOL.

[mtrycraft]

Let us take some of the silliness that has been given here. Suppose you have an amp rated at 100 watts into 8 ohms and 200 watts into 4 ohms. In the US, if that is what is claimed, then the amp MUST meet those specs. Now lets take a 200 watt amp, rated into 8 ohms, which is rated at 300 watts into 4 ohms. Which is the more capable amp driving a 4 ohm load? Yet according to some here, that would not qualify as high current!


8.6Amps for that 300 watts or 7 amps for that 200 watts is not a high current amp:) Certainly not what some companies have advertised:)

[mtrycraft]

I wish someone around here carried AN or Sugden. I'd love to hear them. .

Ah, but you should do that under bias controlled conditions. A different story then for sure.

[mtrycraft]

There are more benefits to high current design than just driving low impedances and it's not just marketing.


How do you test this hypothesis? Certainly not being biased.

I don't think Krell, Levinson, Bryston, Arcam amongst others who are high current

Are they really? Tell us about its amps capability, how high is it?


The higher current allows better control of the driver, especially the woofer,

Are you sure? Where fdid you dig up this bs? Damping factor controll driver and that is determined by the ratio of the output impedance and the speaker impedance. Really. Check it out.

Sugden is more of a unique product and not the norm.

Probaly is. Not sold everywhere, is it.

In some receivers maybe there is some hype.

Yep, amp makers don't hype, only receiver makers. Interesting.


I would use Onkyo as a reference, unless they have recently changed, I guarantee they are high current.

And that current rating would be what? at what impedance? Yes, that is impedanc e related.

Other than Sugden,


How high is the current rating in that amp? Continuous rating? Please inform us. I am really interested to find out of this amp you speak so highly of.


All watts are not created equal.

Then sopme are different? How so? Which ones are different? How? What makes them so?

Don't take my word, do some listening. I think you will find a high current amp will deliver a more powerful and dynamic presentation, much more punch in the bass.

More punch in the bass?


and will hold it's own against amps rated with twice the watts using the same speakers.

Or not.


A high current amp in comparison to other designs will sound like the loudness control is on.

Really? That is a new one.

You will also notice that high current amps will maintain their sound quality better at lower volume.

How so? Why? Please elaborate.

It is also interesting that some of the finest sounding speakers in the world are very inefficient.


That is rather subjective and presumtious on your part, unproven in fact, right?


So what does that say about your poorly designed speaker theory?

Nothing. You havent established facts yet, just speculations.


[/QUOTE]

[hertz]

I changed from a 60 watt pioneer amp to a 60 watt high current NAD an year back.My speakers were clipping with the pioneer and it was struggling and I was convinced that I would need an amp with atleast double the power to drive my wharfedales.I home demoed a 100 watt yamaha and a nakamichi 100 watt reciever and both were struggling with the 86 db floorstanders.But my dealer friend convinced me to try out the NADC 320 BEE and C350 (A 60 WATT amp) at home.Man, what a eye opener it was ! I couldn't believe it ! The difference in quality was awesome and this puny little wonder NAD was driving my speakers effortlessly.
So all watts are not created equally.It is the design that matters.HIGH CURRENT is one of the design FACTORS that makes a BIG positive difference.

[mtrycraft]

I changed from a 60 watt pioneer amp to a 60 watt high current NAD an year back.My speakers were clipping with the pioneer and it was struggling and I was convinced that I would need an amp with atleast double the power to drive my wharfedales.I home demoed a 100 watt yamaha and a nakamichi 100 watt reciever and both were struggling with the 86 db floorstanders.But my dealer friend convinced me to try out the NADC 320 BEE and C350 (A 60 WATT amp) at home.Man, what a eye opener it was ! I couldn't believe it ! The difference in quality was awesome and this puny little wonder NAD was driving my speakers effortlessly.
So all watts are not created equally.It is the design that matters.HIGH CURRENT is one of the design FACTORS that makes a BIG positive difference.


Well, it all depends on what high current is and isn't; what impedance loads those two amps are rated to drive. It is simple as that.
86 dB sensitivity is not that low. All it means is that you can drive it to 102 dB spl with 60 watts if the impedance is withing the amps design parameters.

And, don't forget how much bias is part of that evaluation.

[hertz]

I agree.But all the amps I tried including the yammy and nakamichi 100watters and the nad amps were rated to drive 4 ohms and above speakers.So why does the tiny 60 watt Nad drive my 6 ohm 86 db floorstander with more authority?I finally bought the NAD c350 and I am perfectly happy with it.
On another note: My friend who owns an audio analogue puccini which is again a high current 50 watts amp is driving his B&Ws much better than the 95 watt marantz he owned before.It is driving them better and entire sound stage itself is wider with lots more air around the instruments.
I can speak only from my experience...so there...:)

[markw]

The FTC has less stringent rules to use when evaluating and quoting specs on multi-channel receivers. 2 channel units have a much harder test to pass.

So, if a HT multichannel unit is rated at, say, 60 watts and a straight two channel receiver is rated at the same, you'll get more useful power out of the 2 channel unit.

Likewise, some HT manufacturers can hold themselves to higher then the minimum standards allowed by law. NAD has historically been one to "underrate" their real world power specs as opposed to others.

[Mr Peabody]

What you experienced is typical for those coming to realize there is "high current" amps. 86dB is definitely on the inefficient side. 3dB is exactly double the sound output at the same volume level. Even without a stable impedance the pioner 50 would have some problems.

Some of these guys wouldn't admit there is high current design if there life depended on it. It don't take being biased to know if your amp is clipping or not anymore due to the speaker load. I wonder if mrycraft has ever owned any stereo gear. What Hertz stated was pure fact, he didn't say any of the things I did about better bass and control, though I suspect that was also a result, these things maybe you could shout "biased" because they are more subjective. But one would certainly know if there amp isn't clipping anymore when all other factors remained the same.

[Mash]

Let's consider two (yes, TWO!) equations for Power:

Power = Current^2 * Resistance

Power = Voltage^2 / Resistance

Amps come in two flavors.

A few amps "tend" to be constant (max output) current (i.e. Futterman) and these will deliver MORE power into a higher resistance speaker than they will deliver into a lower resistance speaker, and as well with reduced distortion. A perfect "have your cake and eat it also" deal. (Futterman amps max their output power into a 32 ohm speaker- which is why many Futterman owners rewired 4 ohm Tympani to be 16 ohm Tympani.).

You will find, however, that most amps "tend" to operate as constant (max output) voltage. [The electrical outputs in your house are ALSO constant voltage sources. Hmmm- is there a connection, here?] Constant voltage amps will deliver MORE power into, say, a 4 ohm speaker than they will deliver into an 8 ohm speaker. But how much more is the question..... The Musical Fidelity A2 and A220 amplifiers will deliver EXACTLY twice as much power into a 4 ohm lspeaker as they will into an 8 ohm speaker, so you could say that the MF A2 and MF A220 operate as true constant voltage amps. Any limitations on these amp's output current capability will cause the 4 ohm putput to be less than twice the 8 ohm output. [Note that the electrical outputs in your house do not have a current limitation until the circuit breaker opens.... but the wires will melt before the power grid ever runs out of current.]

So instead of worrying about whether an amp is a "High Current Amp" (which is NOT a defined term), simply evaluate how well the amp behaves as, say, a constant voltage amp. This should tell you everything you need to know about the amp's output current capabilities.....

[mtrycraft]

I agree.But all the amps I tried including the yammy and nakamichi 100watters and the nad amps were rated to drive 4 ohms and above speakers.So why does the tiny 60 watt Nad drive my 6 ohm 86 db floorstander with more authority?I finally bought the NAD c350 and I am perfectly happy with it.
On another note: My friend who owns an audio analogue puccini which is again a high current 50 watts amp is driving his B&Ws much better than the 95 watt marantz he owned before.It is driving them better and entire sound stage itself is wider with lots more air around the instruments.
I can speak only from my experience...so there...:)


Issue of perception comes to mind right out of the gate.

[mtrycraft]

3dB is exactly double the sound output at the same volume level.


What do you mean here? Please explain.

Some of these guys wouldn't admit there is high current design if there life depended on it.

That is just your misbeliefe. But, please tell us what is a high current amp?

It don't take being biased to know if your amp is clipping or not anymore due to the speaker load.

Ah, if it is clipping, it is driven beyond its design specs.
But, it could be a perception issue.

I wonder if mrycraft has ever owned any stereo gear.

Yes, I have two stereo boomboxes. Does that qualify?

What Hertz stated was pure fact,

Well, he didn't.

[Beckman]

3dB is exactly double the sound output at the same volume level.


What do you mean here? Please explain.


He means

10*log(2*Pout) = 10*log(Pout)+10*log(2) = 10*log(Pout) + 3 dB

I think.

[mtrycraft]

He means

10*log(2*Pout) = 10*log(Pout)+10*log(2) = 10*log(Pout) + 3 dB

I think.


At the same volume level?

[hertz]

Issue of perception comes to mind right out of the gate.
mtrycraft,
I have first hand experience with with my amp (nad c 350) and the audio analoque puccini 50 watter which replaced a Marantz pm 7000 which is a 95 watt amp.I am not imagining things here.
I am fortunate to have a dealer friend who stocks high/mid end equipment.I have had the opportunity to try out different permutations/combinations with his resident speakers which are a pair of cadance hybrids.There is a big difference in capability and musicality when you compare serious hi fi brands to the usual japanese recievers / amps.There are exceptions to this rule though but most of them suck big time.I have come to the conclusion that spec sheets are a waste of time.Give the amp some real work to do and you will see the truth.
What you say might be true in a perfect world.But this is not a perfect world.Most run of the mill amps and recievers cut corners all over the place and they can satisfy a casual audio enthusiast, not someone who knows sound.

[skeptic]

It is not the specifications which are flawed. It is the lack of reading the way in which the measurements are allowed to be made and the ability to interpret their limitations which leads to disappointment and misunderstanding. Audiophiles and other amateurs look for a few simple numbers to describe the relative merits of complex products like audio amplifiers and receivers. In fact, a complete description goes well beyond the pile of charts and graphs tediously amassed by one time audio magazines like Stereo Review, High Fidelity, and Audio. Even they only told you the frequency response at one watt. How much attention do people pay to power bandwidth or distortion for example. A 100 watt per channel amplifier at 1000 hz may only be a 20 watt per channel amplifier at 30 hz especially if it has a power supply with a small transformer and filter caps. The FTC stepped in in the 1970s to put an end to the fake horsepower race some manufacturers were running to make their equipment look good, but mass market producers have figured out ways around that and are now right back in there. How many amplifiers or recievers of 30 years ago couldn't handle a 4 ohm load? Not even one I can think of. If you expect something for nothing, you are asking too much. On the other hand, watch out for the 8 wpc guys who tell you "how sweet it is." IMO, they offer nothing for something.

[Mr Peabody]

OK, now I understand your question. I was trying to say that if you had a speaker at 86dB and another at 89dB playing at the same volume level, the speakers that is 89dB will be twice as loud. So 3dB can make quite a difference.

[markw]

OK, now I understand your question. I was trying to say that if you had a speaker at 86dB and another at 89dB playing at the same volume level, the speakers that is 89dB will be twice as loud. So 3dB can make quite a difference.

A 3 db change in loudness is barely audiable. For an apparant doubling of loudness, you need aproximately 10 times the power.

[Mr Peabody]

It takes 10 times the amplifier power to effect a 3dB gain. That's why a 3dB gain is so significant in speaker efficiency. Which is easier and least expensive to achieve more volume, buy a speaker that is 3dB more efficient or buy an amp 10 times as large? It's a fact 3dB is double the sound, that may not be audible to you, but it's a world of difference to my ears.

[mtrycraft]

It takes 10 times the amplifier power to effect a 3dB gain. That's why a 3dB gain is so significant in speaker efficiency. Which is easier and least expensive to achieve more volume, buy a speaker that is 3dB more efficient or buy an amp 10 times as large? It's a fact 3dB is double the sound, that may not be audible to you, but it's a world of difference to my ears.


Actually, it takes 2X the power for a 3dB spl gain and 10X to gain 10dB spl which is perceived as being 2x as loud.

[mtrycraft]

OK, now I understand your question. I was trying to say that if you had a speaker at 86dB and another at 89dB playing at the same volume level, the speakers that is 89dB will be twice as loud. So 3dB can make quite a difference.


Ok, let's try to clarify this too:)

You have two speakers. One will play 86dB spl with 1 watt input power. Speaker 2 will play 89dB spl with 1 watt input power. Is this what you are saying?

Then, it takes twise as much power, or 2 watts for the lesser speaker to play 89dB spl. that is barely audible in most cases as was stated.

To perceive it to sound twice as loud though, you need 10 dB increase in power, 10x more power. Perception is different from power doubling and spl changes.

[kexodusc]

It takes 10 times the amplifier power to effect a 3dB gain. That's why a 3dB gain is so significant in speaker efficiency. Which is easier and least expensive to achieve more volume, buy a speaker that is 3dB more efficient or buy an amp 10 times as large? It's a fact 3dB is double the sound, that may not be audible to you, but it's a world of difference to my ears.

Wow, if it takes 10 times the power to get a 3dB gain, you've got some dreadfully inefficient components.

With all respect to the good Mr. Peabody (a respected site regular) I think his statements prove Skeptic's point very nicely.
With all the statistical figures, logarithmic functions, and mathematical interdependance of stereo components, it's pretty easy to get lost in the specs really quick. Everyone is capable of making honest interpretive mistakes. And the fact that manufacturer's love to make interpreting their figures a bit harder doesn't help either.

[skeptic]

You rang?

I wasn't too anxious to reply to this area but perhaps a few points just to clarify some of what has already been said would help.. Two things are being discussed which are getting confused. Power and loudness. Power is a scientific term. Loudness which is related to power is a subjective term, which describes how we react to a physical stimulus of sound. When the power of sound or of the output signal of an amplifier increases by 3db, it is twice as powerful. When it decreases by 3 db it is half as powerful. But being twice as powerful doesn't translate into sounding twice as loud. That is because our sense of hearing is logarithmic. If you don't know what that means, just understand that to get something to sound subjectively twice as loud it may have to be four to ten times as powerful. This is why the db scale was invented in the first place. The linear scale is just not suitable for describing the power range of our sense of hearing. From the theshold of human hearing to the threshold of where pain occurs is often said to be 120 db. That's a range of 10 to the twelfth power or 1,000,000,000,000 to 1. A 3 db change is perceptable to most people but not that significant. It was believed for a long time that 1 db was the smallest increment of change most people can hear. That's a change of 20 percent. Some people may under some circumstances be able to hear smaller increments. For many people that is a wish and a delusion. Only careful testing by audiologists can map your particular sensitivity to sound and only you can tell us when a sound is half as loud or twice as loud as another. When you do, we can tell you how many decibels of change it took to make it that way.

I hope this helps clarify this apparant misunderstanding.

[mtrycraft]

Wow, if it takes 10 times the power to get a 3dB gain, you've got some dreadfully inefficient components.

.


Sorry, that will not happen. :) It wil still take 2X power to get a 3 dB spl change in those insensitive speakers too:)

[topspeed]

OK, I've been avoiding this thread but now my curiosity is peaked:

Why aren't there measurement standards in place, especially in the US?

There's a completely inane thread on another board regarding taking a 3805 and biamping your mains with the inboard amps in a 5.1 set-up. Forget for a moment that this is an inaudible waste of time, the point is that there are all kinds of screwy calculations going on stating what the receiver is actually delivering with all 7 channels driven. Denon quotes what, 135wpc? Sound and Vision bench tested it and pulled around 70wpc X 7 at clipping @ 1khz (if I remember right. There's 250+ posts in that argument and I'm not looking for it). Considering there is only one power supply, this isn't surprising. What I want to know is why there aren't solid, measurable standards in place? Autos have SAE or DIN ratings, why not electronics?

[skeptic]

Measurements of electronic equipment in this class evolved probably in the 30s and 40s when amplifier performance was so poor that they could tell you usable differences between amplifiers. BTW, even by those limited standards, most of what you read in advertising and magizine tests are very incomplete. Today, most amplifiers are designed to measure textbook perfect by these historical measurements. However, even so, many manufacturers have found ways to manipulate the measurements to their own advantage either by omission or by adding information that may not be particularly useful to most users.

High current capability is one of them. What does it mean. A "high current" 100 wpc amplifier may have enormous filter capacitors in its power supply which can dump 50 amps into a load for a very short period of time. Into an 8 ohm load, that would be 20,000 watts. How long would this be for? 10 microseconds? 2 milliseconds? After a few dozen or hundred milliseconds or so, it would go back to being a 100 watt amplifier. Is this useful? Can some sharp transient attack played back at some monstorous sound level, over some very inefficient speakers with a difficult load show this capability to advantage over its non high current competitors? This arcane performance aspect could be argued at AES seminars by the likes of John Curl and his counterparts who work for his competitors but in the walking around world of you and me, its only real value is probably for advertising something that the other guy doesn't have. And why is that of any value? Because in an industry of mostly me too designs, there is often little else to distinguisl one product of a type from another.

[Mr Peabody]

I agree that amp gain has been confused with SPL. You stated a 3dB amp gain is barely audible, so I think we are on the same page here. Because as we both stated it would take about 10dB of amp gain to make a difference, or as I stated, I have been taught 10dB of amp gain will equate to 3dB of SPL gain. With 3dB of SPL being exactly double. Do you know the relation between amp gain & SPL speaker level? Do you agree that an 89dB speaker will play twice as loud as one 86dB at the same amp power?

Above is what I have been taught. Here are a couple of examples that tends to make me believe what I have learned. I was thinking of buying a Mac receiver from an electronics tech who owns his service shop. When he played it for me, I told him the balance was off. He couldn't really tell it, so he put it on his test equipment and came back to tell me one channel was 2dB down and the problem was in the volume pot which was expensive to replace. The channel embalance was apparent to me.

My son had a pair of Infinity Studio Monitors that were rated in the high 90's SPL or efficiency and I owned a pair of Kappa 7's which were rated at 89dB. One day we were fooling around and I hooked his on one channel and left mine on the other. Granted there is more than a 3dB difference here but I couldn't even hear my speaker when they were both playing, not even the extended low end from my speaker, nothing. I had to unhook his to be sure mine was working.

Also, I put my line of thinking to work in my car audio system with success. I had installed some Infinity Kappa components which were 89dB or less. When I let my daughter take over driving this car she eventually blow a couple of my drivers trying to share with the rest of the world what she was listening to. I told her she had to replace them. She wanted louder, but couldn't aford a larger amp, so I told her when she replaces the speakers to buy more efficient/higher SPL rated speakers. So she bought some Boston Acoustic that were somewhere in the low 90's and with the same amp they will make your ears bleed (figuratively only).

[mtrycraft]

I agree that amp gain has been confused with SPL. You stated a 3dB amp gain is barely audible, so I think we are on the same page here. Because as we both stated it would take about 10dB of amp gain to make a difference, or as I stated, I have been taught 10dB of amp gain will equate to 3dB of SPL gain. With 3dB of SPL being exactly double. Do you know the relation between amp gain & SPL speaker level? Do you agree that an 89dB speaker will play twice as loud as one 86dB at the same amp power?

No, it will not sound 2x as loud. That needs a 10dB spl change which needs a 10 dB of power change. Your example needs 2x the power but audibly is barely audible to most people.

Above is what I have been taught.

There are a number of acoustic books out there. You may want to invest a little in one.

He couldn't really tell it, so he put it on his test equipment and came back to tell me one channel was 2dB down and the problem was in the volume pot which was expensive to replace. The channel embalance was apparent to me.

That may be. All depends on what was playing. Low frequency and you would not be able to tell, nor with high frequency. And, it was affecting the whole audio spectrum not just a small snippit, so you detected it. He didn't.

[skeptic]

Several different ideas and terms still seem to be getting badly mixed up here so I will make a further attempt to untangle them.

"Do you know the relation between amp gain & SPL speaker level? Do you agree that an 89dB speaker will play twice as loud as one 86dB at the same amp power?"

This is really mixed up. If you are referring to one loudspeaker having a sensitivity of 86 db and another one having a sensitivity of 89 db, here is what it means. With each speaker having an input of one watt (this has nothing to do with its impedence but with the electrical power it is drawing from an amplifier at a given moment) then one meter away (about 3 feet) in an echoless environment, the more sensitive speaker will emit twice as much acoustical power as the less sensitive one (at least along its axis.) This does not translate into the subjective sense that it is twice as loud. The perception is more likely to be that it is marginally louder due as I said in my previous posting to the logarithmic nature of the sensitivity of human hearing. Within their linear range which means within their ability to increase their acoustical output proportionally with an increase in electrical input, the relationship will continue to hold so that for the same wattage applied to the more sensitive speaker, it will provide twice the acoustical output as the less sensitive one and will be perceived as marginally louder. BTW, SPL stands for the sound pressure level expressed usually in decibels (db). This is the physical intensity of sound at some given spot. Sensitivity of a loudspeaker is just another way at looking at its efficiency of converting electrical power into sound. Be aware that more sensitive doesn't translate into better sound. There is no correlation between sensitivity and sound quality as examples of both efficient and inefficient speakers run the gamut from awful to excellent.

As power levels increase, each speaker will reach a point where further increases in power will no longer produce further proportional increases in sound level. At this point the speaker will begin to distort badly and if sustained or further increased, the speaker will be damaged. How loud either speaker can ultimately play doesn't depend on senistivity but on other factors related to its construction. Either speaker might ultimately play louder and by a considerable margin given enough power.

"I told him the balance was off. He couldn't really tell it, so he put it on his test equipment and came back to tell me one channel was 2dB down and the problem was in the volume pot which was expensive to replace. The channel embalance was apparent to me."

While the absolute difference in loudness of 3 db may be marginal to our hearing, a difference of 2db between two sound sources emitting the same sound at the same time from different directions may be very noticable. Our hearing meaning both our ears and how our brains interprets what reaches them has evolved to allow us detect the direction of the source of sound quite efficiently. This is undoubtedly an important resource for survival for many animals including man to both avoid preditors and locate prey. We use at least two mechanisms to judge the location of sound, one being which ear detects sound first and another which hears it the loudest. There may be other mechanisms we use as well. In a real musical performance, each instrument has a unique location and the sound from that instrument arrives first and loudest from that location. But in the stereophonic system of sound recording, we use only two channels and two loudspeaker systems to simulate up to 100 musicians and 300 voices all coming from different locations. A musician directly in front of us would have his sound arrive at both of our ears at the same time and at the same loudness. In stereophonic sound reproduction, a recording of that musician should be played equally loudly from both speakers to hopefully fool our hearing into judging that it came from a point between the two speakers and not from either one of them (you can see that after 60 years of this you'd think they could come up with something much better.) If the two electrical channels are not perfectly balanced because one channel of the volume control potentiometer is out of balance with the other or because one speaker is more efficient than the other, the entire effect will be altered but can be compensated for by using the "balance control."

In planning a sound system, many experts advise that the speakers should be selected first. This decision has the greatest effect on the quality of the sound you will hear. Once you have selected loudspeakers, select an amplifier that has sufficient power to allow them to play loud enough to satisfy your needs. This will depend on the size and acoustics of your room and your personal preference. It is also limited by the maximum power your speakers can handle. The requirement can vary all over the place. For example, a highly efficient loudspeaker like Klipschorn in a live room of reasonable proportions may only need a 10 watts per channel amplifier to produce very loud music. At the opposite extreme, inefficient speakers that have a sensitivity of 86 db or less may require 100 to 200 watts per channel or more to achieve the same SPL in a large acoustically dead room. This is not to say either one is better than the other.

I hope this clears up some of your misunderstanding.

One last word of advice. Tell you daughter to turn the car stereo down and keep her mind on her driving. I don't want her crashing into me, I don't appreciate her noise when I am stopped in traffic at a light, and I heard the thumping in my house with all of the windows closed the other night when she drove down my street.