I know everyone hates this kind of response, but, it depends on the speaker. Most would say that electrostatics and some other planar and ribbon speakers have excellent transient response, but they generally have pretty low sensitivity in the mid to low 80db area. There are also some subwoofers that have efficiency of over 93db that are slow as molasses. Regardless of efficiency levels, the transient response game is usually won by lightweight radiation surfaces with short movement, and high power magnetic driving mechanisms. Sometimes this relates to high sensitivity speakers, but not always.
As usual, an excellent response Twl.
Could you be referring to dynamic range as opposed to transient response? If that's the case, higher sensitivity speakers generally appear to sound more dynamic --or have greater dynamic range/swing than lower senstivity models.
high sensitivity usually = poor bass.
Marakenetz - is your response "high sensitivity usually = poor bass" a horns thing, or are you also referring to cone transducers as well - I am on the horns track, fwiw - and you're definitely correct there (the physics are damning)... but I've never actually scratched my head about any cone transducers claiming anything above 93db. Always given that territory to horns. An honest "I'd like to know more" here.
If anyone knows more, and has a moment, let's hear it!
It is possible to achieve good transient response and have high efficiency in a bass driver. Trying to achieve great extension AND high efficiency is a tough thing to achieve though.
The problem with most high efficiency designs in terms of bass reproduction is that they are of some type of vented design. Vents are always slower than an optimally tuned sealed box with a reasonable Q. Since sealed boxes are typically inefficient, there are few that achieve this. One exception is the Klipsch Heresy, which is sealed, has pretty quick and punchy bass ( good transient response ) and is relatively high efficiency ( 96 dB's ). Only problem is that in stock form, it is rolling off pretty hard by about 50 Hz.
Bass horns tend to add their own colouration unless phenomenally well constructed. I've never seen a mass produced model that worked really well from the factory ( in terms of "hi-fi" ). Sean
Again, we arrive at the inevitable conclusion, every design has its flaws.
For Mwilson, I have been using Lowther fullrange drivers recently and they have 98db/1watt efficiency unloaded, 100db/1watt in a cabinet. In my cabinet, they are good down to the low 40's, and they have a resonant freq of 36, so I am not "on the spike", but rather rolling off a few db above it. This leads to a rather steep low cutoff which you can either live with, or integrate a very good sub. Right now I am living with the 40Hz bottom end, and it is quite enjoyable, although there are some records that display the flaw. But, the natural tonal quality, and speed, detail and phase coherence makes up for the 1 bottom octave of missing bass response. I know some disagree with this thinking, but few audiophile speakers actually produce much below 40Hz without some rolloff. So the sound is not really lacking much compared to most others. I have toyed with the idea of integrating a pair of TL subs of my own design, but haven't done it yet. If you have not listened to some Lowther systems, then you should really try to find some to audition. A quite remarkable full range driver.
As as been alluded to, there is a tradeoff relationship between efficiency and bass extension (box size also factors in). It is possible to build a high efficiency system that truly goes deep, but the required box size is pretty big.
There also seems to be a correlation between efficiency and dynamic contrast.
Lately I've been playing around with vented bass systems in the range of 95-98 dB efficiency. By using an unusually large enclosure and tuning it very low, you can get transient response that rivals a fairly low Qtc sealed system. This approach is used with great success by Classic Audio Reproductions, and my own results haven't been too bad. Sean, you might want to try running a few simulations with, for example, a TAD 15" woofer in an 8 or 9 cubic foot vented box tuned to somewhere in the lower 20's. Compare that curve with a Qtc = .6 sealed box for the same driver, and you'll see the potential of this approach.
One of the reasons you typically see high-efficiency speakers using vented enclosures is that the driver parameters conducive to high efficiency (low Qts, medium to high Fs, and large Vas) really aren't suited for other enclosure types. Very low Qts woofers are suited for horn enclosures, but now we're talking refrigerator-size cabinets.
An example of the opposite extreme is the Carver Sunfire line of subwoofers. Carver has chosen to go with an extremely inefficient design (and equalization) in order to get deep bass in an incredibly small box. That's why the Sunfire has such an enormously powerful amplifier.
To the excellent responses above, I would just like to add this readdressing of the thread-head's main question: Yes, it is perfectly possible to achieve good transient response from a speaker design of average sensitivity. But I would also like to point out that the real-world transient response of a given speaker is going to depend a lot on the amplifier driving it, if your definition of "good" transient response means following the impulse accurately without excessive overshoot, undershoot, or overhang - and in the case of a lower-sensitivity speaker, this may require more from an amplifier. Some other things that enable a speaker to accurately track transient impulses include the drivers' ablility to resist compression through efficient heat dissipation, a non-resonant-in-its-operating-range (or well-damped) and rigid-yet-low-mass driver surface, and a wide linear (undistorted) travel range; a rigid and non-resonant mounting and cabinet (if there is a cabinet), as well as rigid coupling of the speaker to a non-resonant floor (or stand and floor); and a high-quality crossover construction that does not introduce its own delays, compressions, or resonances.
Duke, I've heard the CAR's ( or is it KAR's ?? ). I've commented here that i thought they sounded pretty good for a vented system. I do have to say that using very efficient drivers does give you a BIG advantage though when it comes to tuning vents. This has a lot to do with the gains achieved due to a more efficient motor design and the lower excursion rate that results from it.
If one uses a lower to average efficiency driver and uses vents, the driver will go from minimum to maximum excursion capabilities over the operating volume range. This is due to the increased drive levels that one must apply to achieve the amount of pistonic displacement necessary to achieve high volumes with a low efficiency driver. As such, this changes the amount of air and the associated turbulence that occurs in a vent over a pretty wide spl range. As such, most ports / boxes are a compromise that run most efficiently at one specific volume range. Going below or above that results in too little flow velocity or too much through the port. The sonic result of such a design is sluggish bass that lacks damping and / or increased port noise and "one note thud". Being able to find optimum performance on most ported designs typically means that you have a small window of listening levels. Anything below or above that results in slightly different tuning and the decline of performance.
Sealed systems never run into that specific problem as there is always a specific amount of "air spring" or "internal pressure" inside the box. As such, damping remains pretty consistent regardless of volume levels. Sealed boxes do have their problems though in that they do typically require far greater excursion out of the driver, which typically results in greater distortion. Obviously, the driver has to handle a lot of power to make long excursions too, so that is another drawback. Like anything else in audio, we pick our trade-offs and try to minimize the damage done.
Using a high efficiency driver with a port gives you the advantage of having a driver that will not have to "throw" or produce as much excursion to play as loudly. Since the driver will not have to produce as much excursion to perform over the range of average listening levels that most people use, one can more precisely tune the port for maximum flow velocity and damping. This results in a more linear performance over a wider range than what a typical port / low to mid efficiency driver combo would offer. There are times that the high efficiency / port combo may become "destabilized", but a good designer will strive to minimize that effect and / or place that range outside of what most users will run into.
The advantages of working with a low production / high quality manufacturer can come into play IF one really wants to fine tune their system. One can literally design a vented system to perform optimally if most of the variables ( drivers being used, listening room size, spl's required, type of music, etc.. ) are known. By factoring in how much power it will take to pressurize the room to achieve the average listening level and knowing the efficiency of the speakers, one can literally calculate how much air would be moving through a port and size it accordingly. This would maximize port velocity while minimizing such variables as port noise ( chuffing ), lack of damping, etc.. Obviously, this design would be even more specialized than the average "compromise" and may not work the greatest in other rooms or listening situations. Such are the perils of using a port and trying to be as "precise" as possible.
A newer port design on the market ( it's really been out for years but is just making it into commercial products ) is the "Aeroport" or similar products. This design is exactly what its' name indicates i.e. a port that is aerodynamically designed. Rather than using a straight tube, both ends are flared. The bend radius is reduced, which increases flow velocity through the port, minimizes port stalling, DRASTICALLY reduces "chuffing" or "port noise" at high volumes, etc... One can use a slightly smaller diameter port to maintain low spl flow velocity and damping and still not run into port compression ( stalling and chuffing ) until a very high spl was achieved. Since most people are not pushing their systems that hard, it should offer marked advantages and looks like a win / win situation if properly implimented. Sean
Thanks for your enlightening comments! I always enjoy your posts - and learn from them. Your explanation of the problems with low port velocity is new territory for me.
I haven't tried an Aeroport type port yet - but based on your recommendation I will soon. I had thought the only real advantage of flared ports was that you could get away with a smaller diameter port. Lately I've been experimenting with slotted ports running the full width and depth of the cabinet, but it's hard to adjust them once they're built.
...indeed thanks to Sean for such literate clarification. In just my listening experience I've only heard a few of medium efficiency i.e. 89...93 dB/W/m speakers that have a good bass.
I still do not understand people having fun from 100dB/W/m with SET amps. Bassically you can only listen to voice in this case.
Marakanetz, I do indeed enjoy your posts and feel you are a very informed and perceptive individual. On the high-efficiency speaker with SET comment you made, though, I believe you are in error. If you sat down in front of my system which consists of a 1 watt triode OTL, and a pair of Lowther 100db/1 watt fullrange, you would wonder how anyone could say that "voice is the only thing you can listen to". Granted, the bass is somewhat limited to around 40 cycles and there is some "vented" sound to the lowest bass. But,it is very, very good from there on up to 22kHz. As I said in my last post, many other high-end speakers also roll off around 40, and have vented bass, so this is not unusual. Many extreme audiophiles consider this type of system to be the most musical and natural of all systems. They are not idiots. There is definitely something to be said for this type of system. I am hoping that you were exaggerating your point somewhat, because wide-frequency extension is not limited with these systems with the exception of the lowest octave. Some lesser-quality transformer-based SET's may roll off the highs due to transformer induced problems, but not on my system. In any case, the addition of a sub would cover all freq's well, and this is quite common with many types of other high-end systems as is well-evidenced by the plethora of subwoofer threads on this forum. I felt the need to take issue with that statement, because I thought that it was too stereotypical, and an overstatement. Our members who do not know about SET/high-efficiency systems deserve a fair assessment for their knowledge base. I take no personal issue with you, but only wish to set the record straight.
Thanks for honoring my posts, TWL as I honor yours the same. I have many reasons to believe you and probably I should give myself another chance to listen SET/Lowther but did you try to A/B your SET amp with more powerfull amplifier despite having Lowthers 100dB/W/m?
The ultimate tube electronics for me were always Manley and I had a chance to listen to Manley SET amps with Coincident Eclipce. I loved the sound but than I swiched for integrated EveAnna's 50W/ch amp and enjoyed much more.
As Sean stated that everything depends on funds invested into the product and almost every design can succeed in the right combination and it's realy fun for us to find our own equilibrium in funds vs. performance.
Marakanetz, perhaps you just prefer the sound of push-pull amps better than SET's. There is nothing inherently wrong with push-pull amps, and they have more power to kick the bass a little harder. My little Berning amp is actually a push-pull, using 6SN7 preamp tubes for outputs, and maybe that is why I don't feel that the bass is lacking like you say the single-endeds are. Whatever the reason, this little MicroZOTL kicks some booty on the bottom end. Really tight too.
Twl, about the 40 Hz rating. I've heard Brentworth single driver with Waytec SET (20 Hz rated) and the bass was disappointing.
Am I missing something because, take B&W Nautilus 804's for example,are rated at about 40 Hz but they seem to have more weight than the 20 Hz rated single driver? Is this a dynamics issue?
Cdc, the physics of speaker and driver design basically dictate that if you're attempting to reproduce (almost) the whole frequency range with just one driven element, you're going to have to give something up. It could be efficiency, dynamic range, extended bandwidth, optimized dispersion, etc., or a combination of some of the above. The payoff is supposed to be in the quality of "seamlessness" or "coherence" that comes from not dividing up the amp signal, not using different driver types or materials, and not intoducing lobing or phase anomolies, as well as possibly making an easier electrical load without a crossover for a low-powered amp to drive. In your above example, I'm assuming that the amps were also different, which would have something to do with what you heard (as would the rooms and setups), but yes, it's quite possible that a conventional multi-way speaker could exhibit superior bass dynamics. (BTW, what are the tolerances and conditions given [-3dB down or -6dB down? Anechoic, nearfield or in-room?] for the bass frequency response ratings you mention? If they're not the same, then you can't compare the ratings directly.)
I just checked out the Brentworth line on the web, and it seems interesting. Their specs on the top line model show a response of 15Hz-20kHZ within 3db. I find this a little hard to swallow, but they claim it. Seems they have a proprietary loading technique that supposedly allows this to happen. I've never heard them. If they sounded weak in the bass, that would be understandable, as I strongly suspect their figures. However, their idea could be a jumping off point for others to work with, and produce lower bass out of a single way system. The main question is: how do they sound in the rest of the spectrum? If they are no good there, then the bass is of little use. If they are great, then maybe I need to consider them for my system. About the comparison with the B&W's, the B&W's are a well made speaker that conservatively rates their systems, and may actually produce lower bass than their rating, in your room. In any rate, they are a good speaker, and I don't know if the Brentworths are good or not. It is notable that some single driver speaker mfr. is claiming to be able to get that kind of bass response, though. If you can tell us a little more about your impressions of the Brentworths, that would be very helpful.
Hi twl. I heard the $7,500 Type Three-A:
The owner had the best Waytec SET amps and they are supposedly made especially for the Brentworths. I think they were over $8,000.
The room was very big - 18 feet wide x 28 feet deep (guess) so there was no room boundary reinforcement. Maybe sonic treated as well.
Listening in the nearfield these speakers are very clear. Piano was notably richer, fuller than SS gear. Had the distorted immediacy SET's are known for. I heard SET don't do deep bass and maybe with SS amp there would be more bass.
As my girlfriend said, it was all one level. Meaning there were no real highs and no real lows. Also no big dynamics you get with cone drivers. You probably know all this.
I didn't do the test frequencies but bass seemed to be running out around 70 Hz as a very loose guess. That seems really high but I just wasn't getting the base in organ music or the power in bass guitar.
These speakers had the most incredible soundstage I have ever heard. Neil Young live recordings finally made sense. On every speaker I have ever auditioned since, when I play "Needle and the Damage Done" Neil Young is pushed up above the audience. With the Brentworths, he was 20-30 feet away and the audience was understandably located around him. I didn't appreciate this feature until I could never duplicate it again. I thought Audio Physics could after hearing the Step ($3,500 model) a while back but no, the Virgo III's couldn't begin to compare. Maybe Audio Physic lost this feature because the Step's had to-the-inch listener position sensitivity and the Virgo III's sure didn't.
Hearing Michael Jackson's half speed master LP Thriller again had amazing depth and the footsteps were fast but had the SET pleasant distorted sound. This is how records should sound.
I'm not sure what else to say. They weren't for me because I like punchy, full range, dynamic sound and trying to analyze why he bought them, I guess he wants a stereo he can go home and relax with. Also he said the Audio Physics couldn't do the sounstage like the Brentworths.
Well,CDC, it sounds to me like a classic case of a particular design doing some things very well, and some things not so well. Many of the things you didn't like about the Brentworths are not weaknesses in the other brands of single-driver systems. For example, punchy dyanamics and excellent high-end extension are strong suits of the Lowther single-drivers. They are usually somewhat bass-limited by the back-horn designs, but will generally do about 40Hz. As low-excursion 8" drivers, they are never going to "rock your world" in the bottom end category. But, it is there, and solid, and accurate. Fostex will roll off a little early in the high-end, and so will Diatone.
One of the things that concerns me about their claims of 20Hz bottom end, is that your listening experience does not seem to bear out their claims. So, at best, in my book, these claims are doubly questionable now.
About the proper soundstaging you heard, that is a characteristic of good single-driver systems. The point-source and phase coherence really enhances imaging and soundstaging.
I'm not really sure what you mean by "distorted immediacy" and "pleasant distorted" sound about SET's. I don't seem to get that impression at all. I understand they have some issues at some frequencies, but I can hardly believe that the high end Wyetechs were having transformer-related problems. Perhaps it was the speaker's shortcomings you were hearing. Also, I find the taste for bass "punch" is highly variable, with no 2 people really agreeing with how much there should be, for enjoyable listening.
I'm glad you were able to inform me about your listening experience with the Brentworths, since I had no contact with them, and have benfitted from yours. Thanks.
Twl, on SET sound. I've been told they have high amounts of distortion so maybe what I've been told affects my hearing perceptions. Take "Spanish Harlem". The first time I heard on Triangle Celius and Unison SET Rebecca Pidgeon's voice sounded vaguely like if you talk through fan blades while the fan is running. Sort of funny but nice. After a short time I forgot about the "funny" sound and enjoyed the music.
You are right about Lowther being more dynamic. Brenworth's, being planars, vs. Lowthers would probably be like Martin Logan vs B&W in the dynamics department.
I heard some single driver Lowther at HE2002 and they seemed more dynamic and extending than the Brenworths. But I heard some peakiness or unpleasant edginess especially on the piano pieces played and that turned me off. Brentworth's don't do this. Sorry, I find fault in everything. But it beats the "weaknesses: none" response that pops up a lot.
CDC, the new Lowthers do not have the midrange peak anymore. They have been updated and the mids are now smooth. If you heard noise like a "fan blade" out of a SET amp, there was definitely something wrong with it. They do not normally have anything like that in their sound. Perhaps it was going unstable and oscillating for some reason, but believe me, wierd sounds are not normal for SET's. As far as distortion numbers go, they do not relate to the sound of an amp, as the measurements are not taken with music input, only steady-state tones which cannot reflect the amp's behaviour in real world conditions. This is why cheap recievers often have better "specs" than $30k amps. Whoever told you about the "high amounts of distortion in SET amps" has quite a bit to learn about audio. Those types of remarks are the sign of a rank amateur who has not yet learned much about any kind of audio designs. Avoid any more of his counsel, as he obviously is in no position to counsel anyone, since he is in dire need of counsel himself. I advise you to continue listening to various kinds of gear, as you have been doing, since it seems you have a good ear. You will be better served this way, instead of being influenced by prejudicial comments of unknowledgeable individuals. Don't worry about finding fault with everything, because everything has its faults. No design is perfect. If you know the faults, it can help you to decide which type of gear you will prefer. But use your own ears to hear the faults, and don't rely on others opinions.
CDC, according to the Brentworth website, their models use a 6.5" cone single-driver and a combination of aperiodic and transmission-line loading, called BSL. They are not planar types.
How do you make an aperiodic transmission line ? I would assume that the TL was terminated in some type of resistive ( probably stuffed ) vent.
Kind of reminds me of the Shahinian Obelisk. This is a TL that terminates into a passive radiator. Both would be somewhat out of the ordinary approaches. Then again, TL's are not very mainstream to begin with. Sean
Sean, they don't give the details on the website, other than it is a line with "valves" to control air flow. That sounds like what you are talking about with the stuffing. I've never experimented with something like that before. It seems like an interesting concept, but I don't know how well it would work.
"valves" to control air flow? Sounds like the the old Proacs(?) with straws stuffed in the ports (semi ports or multi ports or semi passive radiators?).
Learn something new everyday. And I thought that the covering on Brentworth's opening was the driver. I have only heard 2 SET as dealers don't carry this stuff. Sam Tellig talked with Mike Sanders re Quicksilver Mini Monos / March 2001. Page 36 I quote:
"The distortion is so high with Single-ended that when you put negative feedback around it, you get distortion of distortion. . . The distortion is multiplied so the amplifier sounds worse"
"The annoying thing is the higher distortion, because you don't get the distortion cancellation that you do with push pull. . . So you can't get rid of the distortion of single-ended with feedback: after a while, that distortion just eats away at you".
This is about all I know about SET.
I've only been in this hobby 1 year. Sometimes I think I should've gotten another boom box :)
Went to 2 live shows last month and the musicians and singer were playing through mics / amplifiers / speakers and even though their systems really did have a lot of distortion compared to audiophile stuff somehow it was better. Seemed like that "immediacy" thing people talk about with SET. So I'm interested in SET stuff.
Aperiodic designs seek to combine the damping of sealed speakers with the efficiency and extension of ported speakers. You pick up bass extension and efficiency due to making use of the backwave from the driver ( like a vent ) but the impedance remains low ( typically even lower ) at resonance like a sealed design. The high impedance peak of a vented design is part of what contributes to the "bloated" or "uncontrolled" low end response that lacks definition.
While it sounds like a phenomenal trade-off ( best of both worlds type of situation ), aperiodics ( also called "vario-vents" by Dynaudio and some DIYer's ) don't sound like either design. How such a design would work in combination with a TL is anybody's guess. Obviously, one would have to listed and see if it was their cup of tea. Sean
I am assuming that was Sam Tellig that you quoted. First, he is making a totally "out-of-hand" statement, based on the measurements of a single ended tube amp design. This is obvious, as he refers to "adding negative feedback" as some kind of fix for distortion. It was known more than 25 years ago that negative feedback is NOT a fix for distortion in a real world environment, but only on the steady-tone measurement bench. No really good single ended tube designs that I am aware of, use any negative feedback in the circuit. Their "measured" distortion shows up as higher than SS on the bench, but not in the listening room. It is really sad that a person that writes for an audiophile publication is so ignorant and misinformed. Perhaps now you see why some of us have such little respect for the reviewers in the audio rags. Not all single ended tube designs are great, or even good. But the good ones are capable of doing the job as well or better than any amp out there. No audiophile in his right mind would spend $10k on a single ended tube amp that had so much distortion, that he couldn't listen to it, and no company would expect to sell such an amp. In fact, there are a good number of "hardcore" audiophiles that wouldn't use anything but a single ended tube amp, because they feel that only SET is capable of meeting their stringent sonic requirements. To sum up, a SET does not have higher "real world" distortion, and may actually have less than other amps, measurements notwithstanding.
Sam Tellig is far from the first or only reviewer to comment on tube distortion. There is a school of thought which contends that the reason why tube designs, and SET designs, in particular, have a sound that many find so appealing is because they introduce euphonious distortion. Now, hardly anyone wants to be told (1) that his amp has distortion and (2) that his ears prefer distorted to non-distorted sound. Thus, it isn't too surprising that the euphonious distortion argument is very often met with derision, if not anger.
In an ideal world, we would spend a lot more time saying what we like and why we like it rather than making broad and unsubstantiated (and largely unsubstantiatable) claims. For example, Twl and I disagree about the importance of low end extension, but I admire him for the fact that he doesn't propound pseudoscience in support of his position. He mostly says what the sound is like and why he prefers it. That's a good way to approach these discussions and one that I appreciate.
Those were Mike Sander's (Quicksilver Audio Mini Monos)) quotes, not Sam Telligs'. Mike also said:
"The push-pull had more top end extension, more bass extension, and sounded more solid and controlled. But the single ended had a fastness and a clarity, a purity, and a level of detail that teh push-pull configuration didn't have".
Maybe this is why the SET driven Brentworths had less bass. The guy who owned them did agree that they sounded "different" from other speakers and you had to get adjusted to the sound.
Well, I can agree with the last statement to some degree with some amps, but the earlier statements about the unlistenable distortion is just plain wrong. My statements that were inaccurately aimed at Sam Tellig can now be applied to Mike. Apologies to Sam. And just for the record, I do not have a SET amp. I have a push-pull triode OTL. So I am not on some kind of personal SET crusade or anything. But I have heard some SET amps that are fantastic and could never be characterized as "unlistenable" for anyone.
Twl, have you ever looked at the distortion levels of many "nice" sounding tube amps as power increases ? The distortion curves vs power output are not very linear to say the least. A good example of this can be found in a earlier review of a BAT product in Stereophile. If you remember, there was a HUGE uproar about the test results with this unit when the review first came out.
To top it off, I just saw an "updated re-design" of the Marantz 8B in Audio Xpress. While the factory Marantz was rated at 30-35 wpc, this "new and improved" design that uses a notably bigger power supply, wider bandwidth transformers and automatic biasing should do more power with better frequency response and lower distortion. If you look at the test results, this amp is COMPLETELY "done" at anything above 10 wpc if your criteria is low distortion reproduction.
I would like to see something like an Atma-sphere, Tenor or one of Roger Modjeski's designs on the bench to see how they measure up. My guess is that they would probably be somewhat similar ( albeit better ) to the above mentioned products. I think that much of the "richness" and "harmonic structure" that we hear with tubes are artificial byproducts of the distortion that they generate. I think that most humans like that "feature" of tubes and think it sounds good. However, i don't think that such designs are "accurate".
Please keep in mind that i have 7 different pieces of tube gear that i currently own, so i'm not coming from an SS vs Tube point of view. I think that SS and tube do sound somewhat different in many aspects and one should buy what they like and will enjoy listening to. Sean
Once again, Sean is right on!
I'll try to remember that next time I cue-up a specifications sheet on my turntable. :^)
Twl: Please forgive me for doing my impersonation of Sgt Joe Friday i.e. "Just the facts" : ) Sean