"High Current Speakers" - What Does That Mean?

stretchl

I've seen this phrase a lot lately.

If I'm looking at a spec sheet, how would this be quantified?

Thanks.

zingo

High current speakers are ones that sound their best when driven with a high current amplifier. This can be caused by low sensitivity, low impedance, complex crossovers, rated for high power, or a variety of other characteristics. It is hard to quantify, but power ratings can hint, and your LSi15s are high-current. :cheesygrin: Do you feel your Adcom is keeping up with your LSis?

Does that add more confusion to the topic?

adb3da

I find it harder to figure out which amps are high current. Seems like only Parasound reports amperes in their spec sheet.

mhardy6647

A quick and dirty rule of thumb:
If a (direct or cap-coupled) amplifier can roughly doubles its continuous power rating into an 4 ohm load compared to an 8 ohm load, across the full audio bandwidth (20 to 20 kHz), it's capable of pretty high output current. 100 watts into 8 ohms requires the same voltage as 200 watts into 4 ohms, but twice the current (Ohm's Law).

For exmaple an amp rated for 100 watts per channel continuous ("RMS") into 8 ohms and 190 watts per channel into 4 ohms (at the same distortion spec across the same bandwidth) would be indicative of a "high current" amplifier design.

A transformer or autoformer coupled amplifier (e.g., virtually all tube amplifiers or, e.g., a McIntosh MC-250 or MC-2100) would generally be expected to deliver the same amount of power into any of the amp's output taps (e.g., an MC-2100 is rated for 105 watts per channel into its 2, 4, 8, or 16 ohm taps - or is it 4, 8, 16, or 32 ohm taps?).

heiney9

Specs don't mean much so don't put a lot of thought into it.

Zingo's, explaination seems fine, but I doubt very much that is what's meant. Especially if it has become very widely used as a descriptor in the advertising, promotion line.

If the owners manual is fairly specific it will say in there what the operating parameters are. Anywhere else is just fluff.

H9

nwohlford

adb3da@yahoo.co wrote: »

I find it harder to figure out which amps are high current. Seems like only Parasound reports amperes in their spec sheet.

I would ignore current claims on a spec sheet as there is no standard for the measurement (I believe that HK will state it as well). As noted comparing the 4 ohm and 8 ohm wattage rating according to a specific standard (FTC is the most rigorous) is the best. Actual doubling the current into 4 ohms is rare and often fudged in the specs (either 4 ohms uses a different standard or the 8 ohm rating is underestimated to make it appear to double). A wattage rating increase of 50% or more into 4 ohms usually is classified as high current.

zingo

Manufacturer specs can help, and simply knowing what brands offer high current amps which takes a while. I've found that well-built, high power class D and high current, and a great match for hungry speakers for those on a budget, and a much better alternative to pro amps.

cnh

I agree with zingo as well. And would add almost ALL good quality speakers would benefit from a High Current amp. Even my M-70s rose to another level when powered by something like an Adcom GFA-555 (the difference was NOT subtle). And, of course, if you have lower sensitivity, lower impedance speakers you can't afford NOT to have an HC amp!

Stats are not always truthful. But with respected makers like NAD, Adcom, Hafler, Rotel, B&K, Parasound, etc. You will notice some of what Mark is saying above. Let's take an Adcom GFA-545; 100 watts @ 8 ohms x 2, 200 watts @ 4 x 2.

Basically, if you buy a known and respected amp. You're almost guaranteed it will be a HC amp.

No need to worry! Get your read on. Use the search function here, there is a wealth of info on power amps and speakers!

cnh

gp4jesus

Speakers w/multiple dynamic drivers often need hi-current amps to realize max SQ. Polk's RTi A7s &, in particular, the "'9s" are examples of same; 3 & 5 drivers respectively.

mhardy6647

cnh wrote: »

...
No need to worry! Get your read on. Use the search function here, there is a wealth of info on power amps and speakers!

cnh

... and listen... a lot. Trust your ears.

(Imagine Yoda saying this)

stretchl

Good stuff... good stuff...

Thanks!

I do find a ton of stuff in the archives to read, but most of it is way over my head. Hence the "basic basic" questions.

Regarding the listening, I'm going to have the Yaqin integrated amp that I recently bought in the flea market hooked up here in a few days. That should be an interesting experiment as just about an equal number of people have told me (1) that it will work swimmingly with the LSi-15's and (2) that it will be a disappointment.

tonyb

Are we talkin' speakers or amps ? The guys pretty much covered amps above but speakers, if thats what the OP means, is another ballgame. One of the telling signs that a speaker needs high current to sound their best is the efficiency rateings. Anything below 90 I would say starts to need some current behind them. The lower that number, the more power hungry they will be. Also speakers with multiple bass drivers can soak up the power even if rated at fairly efficient numbers. The current is needed to move all those drivers in and out and even just as important, stop. When the signal hits the speaker, moves the driver, then stops, you may hear bloated notes, too rounded bass notes. Thats the driver not stopping when the signal does basically. Of coarse speaker design, quality of parts also play into this but just a general jist of what current does for drivers. Kinda like a race car off the line with good brakes to stop on a dime.

mhardy6647

The impedance curve of a loudspeaker will determine how much current it is going to require - the frequency corresponding to the speaker's impedance minium, typically a bit above the speaker system's Fs (resonant frequency), will be the point at which it will require the most current. It is essential to remember that a speaker's nominal impedance is just that - a nominal value. Almost all speakers (even today's 'scientifically designed' speakers) show frequency-dependant variation in their impedance curves, representing changes in both capacitative and inductive reactances. Different amplifiers are more or less sensitive to the vagaries of the load's impedance characteristics - This is why there is "synergy" between certain amplifiers and speakers. No black magic (believe it or not).

The only significant exception I know if is that most planar dynamic drivers actually exhibit flat impedance "curves" and behave as fundamentally resistive loads.

In fairness, today's crossovers - electrically inefficient as they are - are usually designed to flatten impedance behavior and minimize frequency-dependent phase shifts (i.e., to optimize the load on the amplifier as much as possible, albeit at the expense of sensitivity). Today's attitude is power is cheap, so who cares how much a speaker needs! :-) (That is not my attitude - but that's another story).

The issue of poor woofer control is predominantly related to the amplifier's so called damping factor (ratio of the load impedance to the amplifier's output impedance; the load impedance is typically specified as the nominal impedance of the loudspeaker in use (e.g., an amplifier with a 0.1 ohm output impedance connected to a nominal 8-ohm loudspeaker load exhibits a nominal damping factor of 80). That said, the control of a woofer's behavior at resonance depends also upon the driver's intrinsic electromechanical properties (which nowadays are summarized in the Thiele-Small parameters) and the design (alignment) and construction quality of the enclosure.

Sensitivity/efficiency is a function of SPL out per voltage in; Ohm's Law will dictate the current requirement.

[Deleted User]

There is iron in your words of wisdom for all Club Polk to read, and so there is iron in your words of life, mhardy.

Face

mhardy6647 wrote: »

The impedance curve of a loudspeaker will determine how much current it is going to require - the frequency corresponding to the speaker's impedance minium, typically a bit above the speaker system's Fs (resonant frequency), will be the point at which it will require the most current. It is essential to remember that a speaker's nominal impedance is just that - a nominal value. Almost all speakers (even today's 'scientifically designed' speakers) show frequency-dependant variation in their impedance curves, representing changes in both capacitative and inductive reactances. Different amplifiers are more or less sensitive to the vagaries of the load's impedance characteristics - This is why there is "synergy" between certain amplifiers and speakers. No black magic (believe it or not).

The only significant exception I know if is that most planar dynamic drivers actually exhibit flat impedance "curves" and behave as fundamentally resistive loads.

In fairness, today's crossovers - electrically inefficient as they are - are usually designed to flatten impedance behavior and minimize frequency-dependent phase shifts (i.e., to optimize the load on the amplifier as much as possible, albeit at the expense of sensitivity). Today's attitude is power is cheap, so who cares how much a speaker needs! :-) (That is not my attitude - but that's another story).

The issue of poor woofer control is predominantly related to the amplifier's so called damping factor (ratio of the load impedance to the amplifier's output impedance; the load impedance is typically specified as the nominal impedance of the loudspeaker in use (e.g., an amplifier with a 0.1 ohm output impedance connected to a nominal 8-ohm loudspeaker load exhibits a nominal damping factor of 80). That said, the control of a woofer's behavior at resonance depends also upon the driver's intrinsic electromechanical properties (which nowadays are summarized in the Thiele-Small parameters) and the design (alignment) and construction quality of the enclosure.

Sensitivity/efficiency is a function of SPL out per voltage in; Ohm's Law will dictate the current requirement.

Excellent post Mark!

stretchl

I was, indeed, asking about speakers.

I'm glad that amps came up, but the fact that they did demonstrates how confusing this all can be to a novice.

newrival

heiney9 wrote: »

Specs don't mean much so don't put a lot of thought into it.

This is as untrue as saying "specs are the only things that matter." Sometimes stats are misleading to those who don't know what to do with them, but saying they don't matter much is even more so.


mhardy, thanks for the great explanation. The way the word "synergy" gets used sometimes makes me cringe.

I had recently had the feeling that things such as system impedance, damping factor, and current get wholly overlooked or misunderstood here. It is good to see that some still take a little science with their religion, so to speak.

Stretch, check out this page of measurements done on the lsi17 and you might start to see some of the vague, nebulous descriptors that get used around here develop some shape. There is a general fear of measurements here by some, but they are helpful within the aggregate of understanding.

ravaneli

Kenneth Swauger wrote: »

There is iron in your words of wisdom for all Club Polk to read, and so there is iron in your words of life, mhardy.

I was ready to type the same when I saw Ken has beat me to it.

Thumbs up to mr. mhardy. Good reason and facts, not often found here.

tonyb

[QUOTE=ravaneli;1826790 Good reason and facts, not often found here.[/QUOTE]

Baloney.....while Mhardy response is on the money, I'm afraid to the novice it means little. We audio nerds tend to get deep, but that can fly over the heads of some who just need a basic grasp of how things work. We can do either here, but as the saying goes,know your audience.

Excellant post btw Mhardy.

ravaneli

I just prefer an objective description of the process that takes place instead of subjective opinion on the results.

cnh

There is nothing in mhardy's wonderful post that contradicts the majority discourse that one finds on this site. I don't understand why some members are taking this opportunity to get in "digs" that are not warranted nor supported by Mark's post? What's wrong boys, moon in the wrong phase for you? Or Male Menopause! lol

cnh

tonyb

ravaneli wrote: »

I just prefer an objective description of the process that takes place instead of subjective opinion on the results.

Isn't it results that matter anyway ? Regardless how you got there or the process involved ? Isn't results by nature subjective ?

tonyb

cnh wrote: »

There is nothing in mhardy's wonderful post that contradicts the majority discourse that one finds on this site. I don't understand why some members are taking this opportunity to get in "digs" that are not warranted nor supported by Mark's post? What's wrong boys, moon in the wrong phase for you? Or Male Menopause! lol

cnh

Who's diggin' ? Everyone applauds the mans post.

gp4jesus

I like mhardy's post.

tonyb wrote: »

One of the telling signs that a speaker needs high current to sound their best is the efficiency rateings. Anything below 90 I would say starts to need some current behind them. The lower that number, the more power hungry they will be.

mhardy6647 wrote: »

Today's attitude is power is cheap, so who cares how much a speaker needs! :-) (That is not my attitude* - but that's another story).

I concur* w/you both wholeheartedly! Everything equal, a speaker w/a nominal sensitivity rating of 87dB will need twice the power to match the output of one w/a 90dB.

mhardy6647 wrote: »

The issue of poor woofer control is predominantly related to the amplifier's so called damping factor.

Sorry Tonyb. I felt the need to edit & expand on certain details of your post. So please read carefully between the []. I hope this make sense to anyone trying to comprehend it.

tonyb wrote: »

... The current is needed to move all those drivers in and out[.] And even just as important [to] stop b]their motion or track the input signal accurately[/b. When the signal hits the speaker [and] moves the driverb]s out (or in)[/b, then (in theory) stops b]them. Then moves the driver(s) to and, eventually, past their resting point moving them in, and then (in theory)[/b stops b]them again, only to then move them to and, eventually, past their resting point again and... well you get the idea.[/b You may hear bloated notes, too rounded bass notes. Thats the driver not stopping when the signal does basically

Amps w/authentic higher damping factors (DF) and "higher current," essentially the the higher the better, do a better job controlling driver motion and/or getting them to follow the input signal, than those w/lower DFs.

Also, at the risk of stirring up trouble, heavy gauge speaker wire, the heavier the better, aids in maintaining an amp's damping/control. In a perfect world w/a perfectly resistive 8 ohm load and, IF your chosen wire had zero resistance, your amp's DF would remain intact. But we know the world isn't perfect, purely resistive speaker loads don't exist, and no speaker wire has zero resistance at room temp.

Finally when/while the signal is "moving the drivers to their resting point" regardless of in or out, the drivers are actually generating voltage* and sending it* to each other and that lower impedance part of the "circuit," your amplifier (BTW engineers refer to this as back EMF). This is what/why the higher quality amps "handle" better than the lesser ones.

So imagine a 7.1 or 9.? AVR having to handle 7 or 9 channels of back EMF versus one or more separate amps. Hence that being THE (my) argument for and use of, complexity aside, as many separate amps w/their PSs for HT as you can make work or your spouse will tolerate.

Like most anything else you can and will reach the point of diminishing returns w/DF, heavy gauge wire, & "high current."

Sincerely Tony