Audio Planet (16)
The Next Step Towards Perfect Audio Reproduction
Written by Super User Thursday, 06 January 2022 17:26Music reproduction, whether in the home or in large public venues, is strongly affected by the acoustic character of the physical space (room) in which it takes place. Reflections and standing waves distort the accuracy of the sound at the listening position from that initially produced by the loudspeakers.
Control and minimization of room effects is one of the critical frontiers of music reproduction. Delivering the soundwave faithfully to the listener’s ears in a typical listening environment is the objective of this development.
The ideal loudspeaker would deliver consistent, accurate, high quality sound to any point in the listening space. Newform’s Coaxial Ribbon LineSource delivers consistent, high quality sound to a larger portion of the listening space than has been possible before.
This approach is inherently free from the flaws of conventional dome based point source loudspeakers and incorporates features which allow an ideal (ideal = the best practically achievable, but almost certainly not perfect) installation to be quickly achieved in many different rooms for many different listeners.
The traditional loudspeaker consists of a larger cone diaphragm bass transducer possibly a cone or dome midrange and a cone or dome high frequency tweeter. This configuration has a number of significant acoustic drawbacks in its ability to deliver the soundwave, that the separate drivers initially create faithfully, through the acoustic space to the listener’s ear. The overlapping hemispherical dispersion patterns of these dome/box loudspeakers using single, small round diaphragms of different sizes for different frequencies staggered on a flat baffle assures cancellation patterns in many directions from the baffle. It also assures that large numbers of room resonances are excited and that reflected sound arrives at the listener’s ear from many different sources at different times degrading the integrity of the original wave created at the diaphragms.
A line source loudspeaker is one with multiple identical drivers arranged vertically in a line or one vertical long driver. The resultant long, narrow diaphragm creates a pattern of dispersion radically different from that of a round diaphragm. Instead of being hemispheric, the dispersion pattern of a line source radiator is resembles a column or cylinder being horizontally broad but with limited and well defined height.
A long narrow driver such as a Ribbon or thin electrostatic transducer also produces a pattern of dispersion that effectively extends the “near field” response, ie the response of the loudspeaker before it is affected by interaction with the room, further into the listening area. The distance the near field effect is projected depends on the length of the effective diaphragm and the frequency it is producing.
Line source loudspeakers (classic electrostatic and Ribbon speakers) have much more controlled vertical dispersion and therefore excite fewer detrimental room interactions but as previously implemented have introduced several other deficiencies of their own. These deficiencies stem from the alignment on the same plane of the drivers in 2 or more parallel vertical lines. By placing radiating surfaces beside each other, the waves created will arrive at different horizontal points in the room at slightly different times causing many amplitude and phase anomalies (comb filtering) which degrade the perceived accuracy of the music.
Only in one very narrow area are these anomalies minimized giving rise to the term “head-in-a-vice sweet spot”. Slight movement of the listening head produces distinctly different acoustical performance. This also precludes more than one listener from enjoying ideal response.
The traditional parallel line source configuration gives rise to the same kind of interference in the horizontal plane that is inherent with conventional dome/cone speakers in the vertical plane.
Besides phase differentials, other anomalies include baffle bounce and diffraction. Baffle bounce occurs when a wave from a driver (typically high frequency) radiates to the side of the driver and “bounces” off of the baffle or the diaphragms of other adjacent drivers. Diffraction occurs when the sound wave encounters a radical change in the baffle surface along which it is radiating - either a corner of a loudspeaker enclosure or the edge of a panel speaker.
For conventional or parallel line source loudspeakers, phase coherence due to the physical offset of the drivers cannot be corrected over a large listening area by electrical means. A coaxial line source holds much higher potential for delivering phase and frequency response accuracy in a large area in any listening space.
Final Step
Newform’s Coaxial Ribbon LineSource loudspeakers with a Ribbon (long and narrow film transducer), placed directly in front of the low frequency transducer line array, have the following advantages:
- extremely even horizontal dispersion
- very limited vertical dispersion
- minimized baffle bounce since the high frequency driver is located ahead of the baffle of the midbass drivers and any high frequency sound reaching the midbass baffle will have very low energy
- minimized baffle bounce since the high frequency driver is located ahead of the baffle of the midbass drivers and any high frequency sound reaching the midbass baffle will have very low energy
- diffraction will be minimized by the small size and contoured shape of the high frequency drivers baffle (front plate)
Advantages of the Newform Research monopole Ribbon in this application:
The Perfect Loudspeaker?
- use of a tall Ribbon driver eliminates the multitude of vertical nodes and cancellations inherent in a line array of small high frequency drivers for example 1" dome tweeters.
- use of the Newform monopole Ribbon is a necessity to avoid excitation and distortion of the high frequency diaphragm by strong low frequency waves created by the midbass drivers directly behind it. A dipole Ribbon (open back) will be “fluttered” by the midbass low frequency output.
- offer greater fidelity in a larger area of listening space than any other loudspeaker configuration
- with the Ribbon in front, this co-axial configuration is highly scalable - the ceiling is the limit with no acoustic downside.
So, having minimized and eliminated some of the major remaining deficiencies of modern loudspeakers, have we achieved perfection? Well, not quite. The experienced loudspeaker enthusiast will point out two issues.
Number one is the placement of the Ribbon ahead of the midbasses which will cause a depth phase alignment shift. This is certainly the case but the audibility of this kind of delay is very hard to ascertain. If a digital crossover is being used, then timing (delay) can be adjusted by approximately 0.5 milliseconds and the drivers are then extremely closely aligned in all three planes which has never been possible before.
The second issue is reflection off the rear of the Ribbon towards the midbass enclosure of frequencies under 1kHz. Even in early prototypes with our standard R-Series Ribbons, (all tests done using 7” ScanSpeak midbasses) we did not hear any degradation we could ascribe to this effect. One would think it would have to exist as the backs of the R-Series are flat and about 3 1/4" wide. Perhaps since the midbass wavelengths are well over a foot, and the back of the Ribbon is within ½” of the cones, the air flows around the Ribbon body very well.
In any case, the coaxial Ribbon configuration was conceived from the start as using a new, narrow, lower acoustic profile Ribbon. Thus, we developed the 2” wide Oval Ribbon to be used in coaxial applications. The neodymium Oval is narrower and bevelled at the rear to maximize flow and radically reduce any trace of reflection.
The Newform Research Coaxial Ribbon Line source technology eliminates several major problems inherent in conventional loudspeakers and is a significant step forward in the reproduction of sound in the home.
Progression
First horizontally aligned LineSource – the usual problems. Very good sound but horizontal comb filtering and high frequency bounce off the midbass baffle were glaring when compared to existing models.
Try the Ribbons in front – Bingo! A new world of room control! Height matters but image is too large for normal seated listening distances. But good for small medium sized public spaces. 8 x 18cm ScanSpeaks dynamics and glorious bottom end – drove with a 600w prototype Spectron digital amp – hurt hearing but uplifted soul.
Line Source Monitor - A smaller soundstage champ in a two foot height. 15” Ribbon with 4 51/4” Peerless subwoofers. Potent package!
Oval formed cabinets and vastly more attractive presenters.
Coaxial Ribbon LineSource Pyramid – a favourite but incredibly difficult for us to build. Also too heavy.
Super Module (Skeleton Speaker) became the best loudspeaker Newform to date. Baffle bounce, floor bounce, diffraction – all minimized.
(bias alert!)
Gets out of the way of the music better than any other design. Better than the venerated R645v3 below – our most popular speaker. Scan Speak Revelator 5” midbasses in the upgrade unit don’t hurt either.
The Last Dance using the Purifi-Audio 4” midbasses has carried the Coaxial Ribbon LineSource configuration to its ultimate expression. Here it is shown beside the classive R645v3. The Last Dance is a narrow speaker but surprisingly tall “in the flesh”.
The Last Dance Compact uses 4 of the Purifi 4” plus a 30” Oval Ribbon. A 45” Ribbon is optional.
Under Construction
Seamless subwoofer integration requires the sub to be placed in the location which minimizes room modes and also produces the fewest cancellations with the main speakers.
As always, get the physical issues optimized and the electronics will have a lot less processing to do.
Listed below are some of the high end subwoofers which almost guarantee excellent bottom end performance.
Older design subs take a little more work. Many include lossy passive crossovers which roll off the main speakers but rob a good deal of transparency. Use these with extreme reluctance!
Many receivers have bass management which forces a high 80Hz crossover. You should aim for as low a crossover point as your main speakers can safely handle.
In the end, any of these systems will produce superb results with Newform Ribbon loudspeakers, especially the new LineSource models as crossovers can be very low and in many cases, the main speakers can be run full bandwidth.
Different room correction and integration systems from different subwoofer manufacturers may produce different results depending on room size and the problems the systems are called upon to fix. This has to do with how the systems handle long time delays in larger or open rooms. However, in “good” rooms, it is unlikely that the results will be anything less than excellent with any of the systems listed below.
Velodyne is a famous subwoofer maker for good reason. We have used their subs at a number of shows and now they come with very sophisticated integration and self-equalization systems. Their approach is unlikely to be significantly improved upon in a decent room.
www.velodyne.com/products/product.aspx?ID=35&sid=572l880v
Paradigm is a speaker manufacturer with an excellent name for great subwoofers at great prices. Their Anthem division produces quite sophisticated processors and amplifiers and their expertise has been applied to their subwoofers.
www.paradigm.com/en/paradigm/subwoofers-paradigmperfectbasskit(pbk1)-series-1-5-30.paradigm
Our perennial favourite product for biggest bang for the buck, the Behringer DCX2496 is a sound reinforcement digital crossover with an incredible array of capabilities. If your subwoofer does not have room correction or a sophisticated crossover built in, then the DCX2496 will offer the next best thing. It is an extremely sophisticated crossover with some basic room correction capability via parametric EQ. It has a steep learning curve but being able to modify settings in the most minute detail on the run is a huge plus. Nothing comes close for the money.
www.behringer.com/EN/Products/DCX2496.aspx
Maybe the most elegant solution of all, the Tact gear has digital crossovers built into their digital amplifiers. As well, probably the worlds most sophisticated room correction is built into their preamp processors. They don’t come cheap but by audiophile standards, the price for this capability is very reasonable when you boil it all out.
www.tactlab.com/AutomaticRC/automaticRC.html
A sophisticated digital crossover with room correction system, the DEQX hails from Australia is very well regarded. It does as much as the Behringer in the crossover department and adds full room correction. It is also reputed to sound a bit better than the Behringer due to its higher grade DACs. It is also over 5 times the price.
www.deqx.com
Major mass consumer electronics brands are now offering room correction and more sophisticated bass management in their receivers. In the past, these have been less than ideally implemented but keep an open mind because these companies have plenty of resources and they are now in the realm of digital where everything gets better and cheaper at the same time. Mostly.
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
Many people notice their hearing declining as they grow older.
Hearing loss does come with age but that is no reason to abandon music. Reduced speech intelligibility can be disconcerting but musical appreciation does not suffer with age. In fact, music can add a great deal to the enjoyment of life.
High resolution audio is a weapon against middle age hearing loss just as a good workout is a good defence against heart disease.
The cleaner music is, the less stressful and more satisfying it will be to listen to. Like moving from a crowded, noisy room to a quiet environment, a well setup high end audio system will delivery a relaxed, intelligible, and highly musical experience.
Ways to improve intelligibility include elimination of noise sources and reduction of strong and discordant reflections. Strong slap echo becomes more disconcerting as age increases so take extra care to reduce, damp or break up bare walls or glass surfaces.
LineSources (line arrays) and Ribbons dramatically reduce the ceiling and floor slap echo to which conventional dome tweeter based systems are prone.
Listening fatigue and intelligibility are inversely proportional. In a public forum poor intelligibility results in loss of focus of the audience and a much less effective presentation. In a home environment, lack of clarity results in progressively less time spent enjoying music and movies.
Our hearing changes over the course of our lives and so does our sensitivity to certain types of noise and response anomalies. We can’t fix, but we can re-adjust effectively.
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
Unless backed up by methodical and appropriate measurements, loudspeaker reviews can be very unreliable.
Acoustic measurements which reliably represent human perception of loudspeaker performance have yet to be developed. The basics are clearly in place though. Smooth frequency response both on and off axis, low driver distortion, low speaker cabinet colouration are all well established prerequisites for excellent performance.
The variables from there however are many. Clearly some speakers perform better in some rooms than in others and some are designed for specific placements.
Dispersion patterns and driver placements on the baffle have a dramatic effect on measured response at different microphone positions and distances. Reviewers who insist on a standard measuring position or distance that the speaker is not recommended for, can seriously mis-represent a loudspeakers performance.
Distortion is something we have always assumed was a critical indicator of sound fidelity. However, once it drops down to a certain level, it ceases to be a reliable indicator. Note the Panasonic digital amp receivers which Newform has so often endorsed. The distortion on the original XR45 model was 0.9% at its rated output of 100w/ channel. On this basis alone, the receiver would be laughed out of any room populated by audiophiles. However, upon hearing the receivers, many experienced audiophiles dumped their much more expensive, better measuring and well reviewed amplifiers for these cheap little lightweight receivers.
Ditto tube amplifiers which also add, in many cases, alarming departures from flat frequency response. But many rational people still love them!
Everyone hears differently and everyone listens for different things. Be very careful when a reviewer waxes poetic about a loudspeaker (or other audio component) whose measured response looks highly flawed.
Ditto for reviews conducted in poor listening rooms. Rooms that are highly unrepresentative of the average room have to be viewed as Distorting the review. If the reviewer doesn’t describe his room, and you are seriously considering the speakers based on his opinion, by all means email him and ask about his listening conditions.
Loudspeaker reviewing, whether in print or on the web, is a highly variable process so get as much background as possible on the reviews of loudspeakers which really interest you.
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
SPEAKERS OF MERIT
There are over 3000 different hifi stereo and home theater loudspeakers on the audio market at any one time in North America and Europe.
Of those 3000, only a very small proportion hold any interest for audiophiles. Once the models designed to hit a low price point are taken out along with units whose aesthetics were more of a consideration than their acoustic design are eliminated, the list gets a great deal shorter.
Drop the cheapies and the throw-together from available parts and you have maybe a few hundred speakers which are well designed and well executed.
Of those few hundred, only a few score are exceptional. Loudspeaker designs have been improving steadily and there are quite a few excellent implementations of classic designs and a handful of novel designs which actually work well.
However, some speaker designers and more likely their marketing departments keep on dredging up well known failed concepts which should have been left behind decades ago. Anything which produces a specific effect or adds character should simply be left in the archives. Loudspeakers whose cabinets resonate like a violin or other instrument should never see the light of day. Ditto speaker diaphragms with cones of some “natural” material which reproduces certain instruments with sympathetic resonances.
Driver alignments on the baffle which create all kinds of interference and comb filtering and a host of other well known speaker design sins keep on being repeated. But not by the designers responsible for the speakers below. There may be better lineups of speaker designs out there but these are the ones we can vouch for in no particular order.
VANDERSTEEN
Vandersteen has dealt with minimization of baffle bounce, diffraction and phase alignment for many years. Add quality components, very solid cabinets and well honed design and you have loudspeakers which stand up well in any company over the long term.
www.vandersteen.com
WILSON
Wilson has occupied the upper end of the loudspeaker market for many years. Obviously their design philosophy is far removed from Newform’s but we can’t ignore their dedication to quality. Their pricing may be over the top but they aren’t all hat. Quality of components, construction and finish plus installation service justifies their stratospheric cost. Also, we have to applaud David Wilson’s down to earth endorsement of affordable but superb electronics. Unique openness for a high ender.
www.wilsonaudio.com
TOTEM
One of the few remaining pillars (totems?) of the once great Canadian loudspeaker industry, Totem makes very well designed and quality speakers with fine finishes in the mid-priced audiophile area.
www.totemacoustic.com
MAGNEPAN
One of our favourite sounding speaker lines and the longest lasting panel speaker manufacturer, Magneplanars offer the transparency and detail that have made the classic panels favourites of audiophiles for decades. Apogees, Quads and Dayton-Wrights round out the first wave of truly great and groundbreaking planar loudspeakers.
www.magnepan.com
ANTHONY GALLO
Innovation and a deep understanding of acoustics meets clever industrial design.
www.roundsound.com
MBL
Basic physics re-defined in a design one would think would be impossible to make work. But it does work and very well. Industrial art and function nouveau.
http://www.mbl-germany.de/Reference_html/101_e.html
PIPE DREAMS
A large line array design among the first to clearly demonstrated the advantages of the line source in home music systems.
www.nearfieldacoustics.com
DR. BRUCE EDGAR’S EDGARHORNS
Although horns really should be relegated to the pages of history, Dr. Edgar’s horns manage to offer the advantages of horns - dynamics, efficiency and impact - while minimizing virtually all of the horns’ inherent flaws. Horn loudspeakers a Newform Research owner could live with. There can’t be any higher praise.
www.edgarhorn.com
PARADIGM
Mass market without the hype - sound engineering and attention to detail shine through in a lineup which spans a wide price range. Their staying power is a tribute to their quality and sound for the $. Paradigm also deserves a gold star for their valiant attempts to maintain as much production as possible in North America.
www.paradigm.com
Although Newform feels its dynamic, wide dispersion Ribbons and Coaxial LineSource speaker arrays betters the competition in many areas, the above companies are solid audiophile citizens and deserve full credit for the excellent products they produce.
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
AESTHETICS
Newform Research loudspeakers are extremely high performance audio designs. But often life interferes with the pursuit of pure high fidelity.
The dreaded WAF or SAF (spousal approval factor) can quash a music only decision and turn it into a lifestyle decision.
Where a dedicated room is involved, the audiophile may have complete acoustic freedom. When musical performance is not the only factor in the purchasing decision, then both the looks of the loudspeaker and it’s placement in the room have to work with other considerations.
Our loudspeakers look technically unique because they are very technically focussed. The cabinetry can be very handsome but for us, form follows function. Although Newform loudspeakers have a unique look, they can be integrated into room decor as well as any tall loudspeaker and considerably better than many of the $50,000+ behemoths which are widely available.
We do custom speakers and grills so there are a few aesthetic options that are open to you when you come to the conclusion that Newform Research loudspeakers can deliver the audio performance you have been waiting for.
Loudspeaker repair is generally quite simple if you have the right replacement woofer, midrange or tweeter and a soldering iron on hand but first we should say a few words about why speakers fail.
Whether it is hifi stereo, home theater, sound reinforcement, automotive or PA loudspeakers, the most common cause of failure is too much of the wrong kind of power. Not too much available power.
When overdriven, an amplifier “clips” the top off the sine waves it is trying to produce because it reaches its maximum voltage ceiling. This clipping effect produces a large amount of high frequency energy which goes straight to the tweeter. Tweeter burnout is the number one type of loudspeaker failure.
A 200w per channel amp is less likely to fry tweeters than a 50w amp because it has so much more headroom and can produce a cleaner wave at higher power.
Low power amplifiers can burn out any tweeter and low power amplifiers are more likely to be overdriven. If you hear the sound becoming hard or distorted, that is the sound of clipping. Back off!!
The next is woofer burnout or overdriving which causes scaping or rattling. Crossover components rarely fail except in extreme cases. If you can see the woofer cones moving, they are being driven fairly hard. Use common sense.
Once you have diagnosed the problem, you can call the dealer or service centre and decide if the speaker is worth repairing.
If you can’t get any support or if you would like to tackle the repair yourself, here are some steps to consider.
1. Pull out the defective driver.
2. Do the battery test on it. A volt meter impedance tests works as well. Don’t be alarmed if your 8 Ohm speaker tests as low as 4.5 Ohms, that is a dc reading and the 8 Ohms is only nominal.
3. If it is “dead”, time to track down a replacement.
4. If it is live, then the issue is inside the enclosure (very rare) and you’ll have to pull the crossover.
A FEW TRICKS
How do you know your speaker has failed? Could it be a connection? Apply the voltage of a small 9 volt or smaller battery across the binding posts (with the amplifier speaker cables disconnected) and see if you get a lick or pop. If you do, the speaker is working to some degree. Check your wiring to the amp.
If there is no sound or distorted sound, press gently in on the cone of the woofer with your fingers spread across the diaphragm. If it doesn’t move, it is fried with the voice coil melted and jammed in the magnetic gap. If it does move but scraping and scratching is audible, it may not be as bad but it probably indicates the driver still must be replaced.
If the scraping goes away when you push on only one side of the cone, a mickey mouse fix is possible if you can’t get a replacement woofer. If this is a nothing to lose situation, take a piece of masking tape and stretch it over the baffle and over the side of the cone so the tape slightly presses on the rubber or foam surround. This can equate to your finger pressure. If this works, you can try something more permanent with duct tape.
Note this is a last resort and the frequency response of the speaker will be affected. Also, taking off the tape may well rip the woofer surround.
If it is difficult to pry the woofer or tweeter out of the baffle without damaging it, here is an option.
Find a screw slightly larger than the screw hole on the frame of the driver. Turn the screw into this so it becomes jammed. No need to really force it in, just make it snug.
Take a small wood block, place it on the baffle beside the screw and use a hammer to pull up the on the head of the screw. The driver should come up with it.
Repairing Newform Research speakers is a little different. If a Ribbon fails, call us first. Absolutely do not take off the faceplate as this will result in further damage. Our Ribbons are extremely robust so failure is very unlikely. Our Ribbons require no maintenance. If you detect a problem of some kind, if the Ribbons are making sound, they are almost certainly working to spec. Look elsewhere for the problem and talk to us!
Where can you get replacement speakers? The number one source in the USA is Madisound (www.madisound.com ) who is also a large supplier of loudspeaker kits for DIY projects.
In Canada, Solen Electronics is the source (www.solen.ca).
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
The custom home theater installer has to blend the conflicting issues of video and audio excellence with complex electronics into a simple to operate, aesthetically pleasing package.
Newform Research Ribbon systems can make the installers acoustic job a great deal easier providing the home theater room design allows for speaker placement clear of the front wall. Let’s be frank. Putting Newform Ribbon speakers inwall will work well enough but it is a huge waste of their potential. Rears and sides can be installed inwall as those channels are far less critical and sound field ambience may even benefit from the delays and reflections inherent in inwall placement.
Given their high impedance, dynamics, broad horizontal dispersion and modularity, Newform Ribbon systems are configurable to virtually any application. Control of vertical dispersion is also a very useful characteristic of these Ribbons. Needless to say, their sound quality is also superb.
Custom designs with a variety of high end midbass drivers in custom finished enclosures can be a great help in meeting high customer expectations for world class systems at realistic prices. The Coaxial Ribbon LineSource designs will allow you to offer your customer an unsurpassed acoustic experience.
If you have a home theater or high end audio project which calls for ultra system musical performance, contact us to discuss it.
Loudspeakers Unsurpassed in Soundstage, Transparency, Detail and Dynamics in High End Stereo and Home Theater Systems
The audio setup for a home theater system is very much the same as the ideal audiophile setup for stereo. The trick is to not allow the video screen to interfere with the acoustic performance not to allow the addition of rear speakers or subwoofers to detract from the key goal, overwhelmingly delivered by the front speakers, - the ability to play music.
There is another complicating factor in home theater design. That is aesthetics. Very often high end home theaters are pictured with inwall speakers - virtually invisible.
From a high fidelity audio point of view, this a huge compromise. In order to set up a natural soundstage, loudspeakers - any loudspeakers, not just Newform Ribbons - have to have space around them. Place the speakers as far out from the wall as possible without blocking off part of the screen from any seating position.
Inwall speakers simply generate more baffle bounce and front wall reflection. Although they may be able to blast large amounts of sound at you and the center channel speaker might be able to help anchor the audio images, the overall effect is more like an acoustic assault from several points rather than a naturally rendered 3 dimensional soundfield.
There is no reason a home theater room cannot do as good a job with music as a dedicated high fidelity room. As long as the screens are flat and the loudspeakers are well placed, acoustically speaking, home theater rooms and high end audio rooms can be identical.
If the front speakers aren’t set up to reproduce music well, then they will do a poor job on home theater as well.
With just the same toolbag of tricks you developed in your pursuit if high end audio, you can make create your own audiophile home theater.