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In Reply to: RE: Hasn't hapened yet posted by PakProtector on August 13, 2011 at 06:33:01
Same answer below - speakers that are easy to drive. If a SET amp is not giving you the bass slam and drive or treble sparkle it is one of two things - A) it's not a good SE amp or B) the speakers are no efficient enough and are causing the amplifier to run into distortion which then becomes a fuzz box of mush.
And no - not all horns are easy to drive. High efficiency is far more important than high sensitivity.
Follow Ups:
----High efficiency is far more important than high sensitivity.
Do please define the difference so that we'll all be talking about the same thing please.
On your A and B possibilities, I've got speakers that play well with SE amps, they've been subjected to enough of them with the amp's owners pronouncing the combination Good I think I can exclude that option.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
High Efficiency is simply a speaker that does not possess low minimum impedance and Audio Note argues that they also should not have high minimum to maximum impedance swings either.
As an example - My speakers are 92.5db sensitive (in corners) 89.5db not in corners) (measured by Hi-Fi Choice) but they never drop below 5ohms nor do they go above 12ohms. My amplifier has a 4 ohm tap making it very easy to drive - easier than a 105db sensitive speaker that drops to 3ohms. The AN J is actually easier to drive than the AN E which drops to 3.6 ohms for a large section of the lower octaves - even though the AN E has a higher sensitivity rating it is harder to drive.
Still the AN J has no problems with bass, bass tightness and control, and the modest 10 watt amp I used (4 undistorted) is never needed past the 11 o'clock position on a full rotation pot. I get deep (sub 30hz) controlled bass at leave the room volume levels.
The Meishu is a 300b and in a much larger room the 8 watt beastie had oustanding grip and the ability to play louder than I am comfortable listening with "I can't believe there is no sub" kinds of bottom end. Granted I don't have a ton of experience with lesser grade amplifiers but to me the synergistic match is important with SE amplifiers. I think the Jinro has more grip than the Meishu but that is a 211 tube thing I believe - as from what I can tell the 300B people seem to find a mellower type - but that's another issue - the Jinro has a ton of command and grip and dynamics and headroom galore. And the AN speakers are not the easiest of speakers - there are even more efficient and more sensitive speakers out there.
"High Efficiency is simply a speaker that does not possess low minimum impedance and Audio Note argues that they also should not have high minimum to maximum impedance swings either."
Do you realize the absurdity of this comment? Just one simple example ought to show you the error of this thought process.
Maggies are probably the most linear load any amplifier will ever see. Are you now proposing that 87dB sensitivity planars are "High Efficiency"?
Granted, no power is lost trying to drive 2 ohm loads, but really?!?!?
I addressed this below - the problem with Magnepan - is that most of the Magnepan owners all yell at me saying you need HUGE SS amplifiers with 150 watts to drive them properly. t I then point out to said Magnepan owners that right on their website they claim to use a 40 watt RECEIVER to drive them just fine. I in fact drove the 1.7 with a Soro - a sub 20 watt SE tube amplifier and got the best results that I have ever gotten from any Magnepan speaker. For $1800 it's quite good - much less impressed by the more expensive models however.
----High Efficiency is simply a speaker that does not possess low minimum impedance
I always thought high efficiency was reserved for things that did a better job of converting input power into output SPL. IIRC there is nothing in the term regarding impedance.
Further, it is quite possible to design and build a speaker that is one Ohm and varies very little around that value while delivering 100dB/1W-1m. Now this would present issues to the usual impedance matching articles with 8 or 16 Ohm matching taps.
Instead of butchering the language, it might serve you better to recognize we don't all like the same things.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Douglas
> > Instead of butchering the language,
If you think about it it isn't butchering.
Speakers convert electrical power into
acoustical power so when the impedance dips
it is drawing more power and so it is
less efficient than another speaker of
the same sensitivity with flat impedance.
DanL
----so when the impedance dips
it is drawing more power and so it is
less efficient than another speaker of
the same sensitivity with flat impedance
This makes a few assumptions...such as IFF this impedance dip happens and no more SPL is produced. In any case, since tube amps typically have higher output Z than SS ones, and SET w/o nfb usually top this list a change in the load does not work well. That is not what I am worrying about...couldn't care less actually; it is a red herring.
I've still not seen the description from RGA as to the difference between sensitivity and efficiency. When he delivers that( if he ever does) the discussion will continue.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
"One misleading piece of information with which our customers are often provided is sensitivity. This specification is commonly misrepresented as "efficiency" which it most certainly is not. Loudspeakers are terribly inefficient and it is likely that virtually no consumer has ever been given an actual efficiency specification. The most efficient loudspeaker designed to date was the Altec Lansing Voice of the Theater, which had an efficiency rating of approximately 3.6%. No loudspeaker manufacturer would ever publish an efficiency specification because it would discourage and mislead consumers. Be clear on one point: sensitivity and efficiency are not the same thing. Even when using a solid state amplifier, one cannot necessarily equate high sensitivity to high efficiency - the physics are simply more complex than many manufacturers, and sadly reviewers, lead us to believe.Instead of efficiency, loudspeaker manufacturers provide a sensitivity specification. This figure is supposed to indicate how loud a speaker will play when fed one watt of power, or 2.83 volts, listening from one meter away. The problem with this measurement is that the conditions under which it is to be recorded are not well defined and hence the figure does not provide a consistent "apples to apples" point of reference. For one thing, the input sensitivity (gain) of the amplifier used to measure the sensitivity is unknown and unspecified. More importantly, while the specification calls for measurement at one meter away, the conditions of the listening room are not defined. It is not clear whether measurement is to occur in an anechoic chamber, a concert hall, a coat closet, or a gymnasium. Each of these rooms will yield remarkably different sensitivity readings at one meter from the speaker.
The most important lesson to learn from the above discussion is that for the purposes of determining tube-friendliness, sensitivity is essentially meaningless. Many tube gurus insist that one must use speakers with sensitivity ratings of 90 db or higher. This is simply not true. Many speakers with high sensitivity ratings are poor choices for tube amps, just as many speakers with low sensitivity ratings often work quite well. Why is this so?"
I suppose the word efficiency should really be changed to "ease of drive" since according to the above all speakers are not the least bit efficient - however a speaker of 85db sensitivity can be a LOT easier to drive than a speaker rated at 100db sensitivity.
So we need a word that illustrates this "ease of drive" attribute. Simply playing loud with 1 watt doesn't mean it's playing well with 1 watt.
Edits: 08/14/11
"More importantly, while the specification calls for measurement at one meter away, the conditions of the listening room are not defined. It is not clear whether measurement is to occur in an anechoic chamber, a concert hall, a coat closet, or a gymnasium."
Do you know of a speaker that has specs that are taken from other than in an anechoic chamber?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Most speakers are not tested in an Anechoic chamber - since most makers don't have one.
My Audio Note speakers are rated in room corner loaded since they were designed for corners - quasi anechoic measured speakers try to take all room boundaries including corners out of the equation. Therefore the measurements done quasi anechoic will be lower than real world results when positioned according the manufacturer. Corners gain 3db of sensitivity and up to 18db to low frequencies. This is why both Hi Fi Choice magazine and Hi-Fi Critic (Martin Colloms) measured and found the AN E to be 94.5 db sensitive and 17hz -6db (hi-Fi Choice 23hz -3db) while Stereophile which measured center of room (one loudspeaker) got 92.5db and ~28hz.
Apparently, anechoic style measurements also don't really provide accurate information about Electrostatic panels either due to their radiation pattern (ie their sensitivity is rated lower than their real world results at the listening position).
I am not a big fan of most of these specs because it takes people out of the listening. Here is a simple truth to figure out the specs - listening
1) speaker is set-up
2) amp is 8 watts
3) I get very loud very deep bass with any music
THEREFORE = system has high "enough" efficiency/high "enough" sensitivity/ High "enough" ease of drive
1) speaker is set-up
2) amp is 8 watts
3) Sound of bass is mushy, slow, lacks control distorts, treble is rolled off
Therefore = no matter what the specs and measurements the speaker does NOT possess high "enough efficiency/sensitivity/ease of drive"
But you can tell all of this with listening - no one really needs to read the spec sheet to hear if the system (speaker/amp) is having problems - if you need the spec sheet and the measurement to tell you this - then you don't really have very good ears so why bother spending money on high end audio equipment - you may as well go to Wal-Mart and buy the Home Theater in a Box for $129.99.
"But you can tell all of this with listening - no one really needs to read the spec sheet to hear if the system (speaker/amp) is having problems - if you need the spec sheet and the measurement to tell you this - then you don't really have very good ears so why bother spending money on high end audio equipment - you may as well go to Wal-Mart and buy the Home Theater in a Box for $129.99. "
I agree with all of that.
JBL has an anechoic chamber pictured above.
I would be surprised if most of the driver manufactures don't.
MacIntosh has one.
http://www.roger-russell.com/cham2pg.htm
Energy has one.
http://www.energy-speakers.com/na-en/products/rc-50-specifications/
Axiom Speakers use the one at the National Research Council in Canada.
http://www.axiomaudio.com/NRC.html
Microsoft has one.
http://gizmodo.com/5372268/microsofts-anechoic-chamber-the-place-where-sound-goes-to-die
Meyer Sound has one.
http://www.meyersound.com/products/technology/chamber.htm
Stetron International has one.
http://www.stetron.com/resources/archives/stetronenhancesspeakerdesign0/
OK, sorry. I'm done.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Yes some of the bigger makers have them - unfortunately it doesn't really translate into the best sounding loudspeakers in real rooms.
This is why magazines tend to review speakers in a free standing position to try and emulate the anechoic condition for measuring sensitivity. Doesn't help any speaker not designed for a free standing position or one that doesn't take into account room boundaries (such as my speakers). Granted corner loaded speakers are in the minority and so are panels - but an accommodation should be made in such cases - and they generally are not.
"Granted corner loaded speakers are in the minority and so are panels - but an accommodation should be made in such cases - and they generally are not."
I agree again.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
hey-Hey!!!,
the marketing surrounding efficiency/sensitivity is misleading, and deliberately so. However, the xxx dB/1W-1m is another measurement of efficiency( what ever the number happens to be ). Note that is says 1W, not some other number dependant on a voltage applied to an unpublished impedance. At 100% efficiency, in defined space, at specified power SPL is the dependant variable.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Electrical load vs. Frequency and Phase Angle vs. Frequency can't be quantified into a single measures over the entire frequency range. Most LS3/5As (certainly the 15 ohm versions) work "reasonably well" with as little as 3W and very well with 8W, even though they are 82 or so dB sensitive. Of course, they have limitations that even 100W of any kind of amp can't overcome. So do Audio Note Ks, although they do not present quite so benign a load as an LS3/5A. Js, and E and HE E's, of course, do a better job due to their higher sensitivity. But if you are living in Japan and your living room is 3Mx3M (if you are that lucky), the smaller the box, the better!
Wait and see.
"What did the Romans ever do for us?"
This is why I don't pay too close attention to watt ratings or sensitivity ratings. It doesn't really matter - what matters is speaker A connected to amp B and does the combination produce the levels and bass and grip required.
The AN J is 93db sensitivity - the amp is 4.2 watts undistorted in a 13 X 16ish room is deafeningly loud with sub 30hz bass - I also had the AN K in this room and it played louder than I would ever need.
The AN E/Spe HE at CES with the Jinro had some of the best bass at the highest levels of any room at the show easily and convincingly bettering rooms with 1000 watt amplifiers. I guess people play at extreme levels when the make their judgements on this - if so they'll be deaf very soon and so the point is moot.
But we live in the real world and not in a theoretical one - we might be able to build 1ohm speakers with 100db sensitivity - The real world we get stuck with dumb designs like the Apogee Scintilla which goes down to 1ohm with horrible sensitivity and when you can get an amp to drive it - the sound is phenomenally overrated (read lousy and a good reason they went belly up because most people when hearing them chortled to themselves when dealers told them the price of the things).
A flat impedance of 4 ohms would be better than one that dips and dives but is rated at 8 ohms nominal. Magnepan is fairly stable at 4ohms and so there is no good reason a SET can't run them - indeed, the Audio Note Soro at ~15 watts drove them better than 150Watt plus Bryston - the bass was deeper and weightier on the Soro too so there!
"What Tubes Want
Tubes like a resistive load - it's really that simple. A resistive load translates to a flat impedance, and an inductive rather than a capacitive phase angle. A less technical way of looking at an ideal speaker from a tube's point of view is as follows: tubes like consistency. They prefer a speaker that doesn't swing from 8 ohms to 2 ohms and back again. If the impedance is going to dip it should do so gradually, or in small dips. Tubes like a steady load - capacitance is the opposite. When a speaker behaves in a capacitant manner, it presents an uneven load to the amp, asking for current in sudden spurts. Tubes don't like to pump out current at the drop of a hat. They prefer a consistent and predictable load.
Naturally it is sometimes difficult for speaker manufacturers to keep all the aforementioned variables in their ideal ranges. If phase angles must be capacitive, impedance should be high. The lower the impedance, the flatter it must be, and the less capacitive the phase angles must be. All three variables (slope of impedance, value of impedance, value of phase angle) together determine how good a match a speaker will be for a tube amp.
For this reason, the argument that only speakers with an impedance of 8 ohms or higher will work on tubes is incorrect. There are many tube friendly speakers whose nominal impedance is 4 ohms. If the speaker's impedance is relatively flat and consistently hovers around 4 ohms, and if the phase angles are only slightly capacative, or better yet inductive, there is no reason why a 4 ohm speaker cannot perform well on a tube amplifier. Some of our favorite tube friendly speakers are 4 ohms! It is also important to recognize that one need not use the 4 ohm taps on a tube amp with 4 ohm speakers. Many 4 ohm speakers sound their best when hooked up to 8 ohm, or even 16 ohm taps. If the speaker presents a resistive load (i.e. the impedance is flat - even though it is low) the 8 or 16 ohm taps will work fine, and always sound better than the 4 ohm taps. If the speaker requires more current because the impedance is low and and not terribly flat, the 4 ohm taps will likely offer better bass control at the expense of definition in the highs and mids." http://www.dhtrob.com/overige/tubefriendly_lsp.shtml
A solid state voltage source amp into a low speaker impedance like 2 ohms plays louder than 4 ohms or 8 ohms. This we know. It doesn't make the lower impedance loads more efficient in actuality, as any tube amp would require a need to change impedance taps for each condition. The SS amp if very strong in current can keep on delivering more power out into lower speaker impedances, but the watts are also increasing, not making this actually more efficient. But some manufacturers will show a dubious figure like 91dB/2.82V/1m, where the voltage of 2.82V will deliver one watt into only 8 ohms. But the intended amp with it works in lesser impedance, and thus this figure is misleading. Then at 4 ohms the power is actually doubled by the voltage source SS amp to 2 watts.
True speaker efficiency is measured in percentage. It's the amount of acoustic power developed for power inputted. A driver could be 2% or 20% efficient. An open framed driver is much less efficient than the same in a loaded compression chamber. There's physics there I don't care to get into.
Then after the efficiency is increased, the sensitivity can be increased which might be 110dB/1W at 1m away. This will be done by the method of impedance matching to the air, and waveguiding the output of the driver to concentrating the energy with directionality to a narrower beam.
Impedance contouring and control is another effort to ease the load for the amp, and by electrical theory all amps like an easier load to drive to make voltage out remain what it should be.
There is a fallacious theory about SET amps that high output impedance makes them unable to follow even minor impedance changes with frequency. Actually, the voltage sourced amp is harder to make a flatter acoustic response to small variations. SET amps are partially voltage sourced and partially power sourced outputs into speakers.
With a 'flat' response speaker, a SET amp will *RAISE* power output when a small impedance rise occurs: small higher impedance usually correlates with small lower output from the speaker with the crossover. Only the open zero NFB amp can help. On extreme impedance change, it's not as good.
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