Product News

Pure Reference Extreme

Statement MC Step Up Transformer

Available Options on Coincident Speakers

Technical Notes

Passive vs
Active Preamps

The Coincident Sound

Why Biwire?

Cables: What is Important?

Mirror Imaged Woofers

Amplifier Power: How Much?

Loudspeaker Impedance
and Amplifier Matching

 

Pure Reference Extreme

Editors Choice The Absolute Sound

Super Victory

Editors Choice The Absolute Sound

Partial Eclipse II

Editors Choice The Absolute Sound

 

 

2011 Saw Another Year with Many Prestigious Awards
Garnered by Coincident

Pure Reference Extreme Golden Ear Award The Absolute Sound Editor's Choice The Absolute Sound High End Audio Class A Super Victory Editor's Choice The Absolute Sound Statement Phono Stage Blue Note Award Enjoy The Music Highest Recommedation Award Stereomojo High End Audio Class A (lower) Statement MC Step Up Transformer High End Audio Class A

 

 

Coincident Pure Reference Extreme Loudspeaker
$ 26,800
by TAS Issue 215

View printed review

The Coincident Pure Reference Extreme (CPRE) may be the most accurate and true-to-life loudspeaker on the market today. It's actually the opposite of the MBL. It does not recreate a concert, it does not beautify recordings; and it looks relatively ordinary. Considering all the MBL does right, the Coincident does the same things more realistically and correctly. It is a thinking man's loudspeaker that speaks the truth whether or not you want to hear it. When I say more realistically, I mean that literally. The imaging is the best in the business. It's exactly what the microphone(s) picked up and it replicates what the recording engineer intended you to hear. Let me be clear: The Coincident allows you, for the first time, to experience that actual craft of the engineer. Countless examples of crappy, thin, or compressed recordings are deconstructed by the Coincident and reassembled in a more realistic fashion. It's as if other speakers smear the sound. And it's all presented, phase perfectly, in a broad array across your room-an immersive Holodeck of sound.

The CPRE is a three-way design that functions more like a two-way with a subwoofer. Its super-fast ceramic Accuton mid- and high-frequency drivers cover the ground from 100Hz to 27kHz. The woofers are tonally correct with perfect pitch and definition. If you are accustomed to midbass (chesty) exaggerations, you'll have to rewire your thinking. Once you do, you'll never go back. The crossover is simple and first-order. The sensitivity is 94dB, and the load is tube-amplifier-friendly.

Over the years, TAS Executive Editor Jonathan Valin has “ticked” numerous Magneplaners as the best bang-for-the-buck in high-end loudspeakers (and does again in this GE-Ed.). I'm going to add the Coincident Pure Reference Extreme as one of the very best performance-for-dollar products in the ultra-high-end market today. The CPRE is downright magical with low-output triode amplifiers, but is also surprisingly realistic and vivid with big solid-state amps. Not to mention, it's out of this world with vintage Heathkits and Fishers. The CPRE is on of the most versatile and realistic loudspeakers available today. (Reviewed in Issue 209)

 

 

 

 

 

We are now excited to introduce the MK. II version of the highly acclaimed Dragon amplifiers. The improvements include:

1. Dual power transformers in place of the previously used single unit. The new transformers individually possess the capability of powering the amplifier. In tandem, they are coasting only using less than 25 % of their rated capabilities. The result is a far cooler operating amplifier, thereby improving reliability and long term
stability. Additionally, the Dragon is now virtually noiseless. It is incredibly quiet which is a remarkable feat for an amplifier this powerful operating at such high voltages. Sonically there is an improvement from top to bottom. The bass is tighter, deeper and punchier. The mids and highs are more transparent and the soundstage more expansive. Due to the reduction in noise, overall revelation of low level detail is enhanced.

2. Chassis Rigidity - To accommodate the dual transformers of the MK. II Dragons, the chassis has been enlarged by 20%. The amplifiers are now 2" wider and 2" deeper and 1" higher. They now weigh 85 lbs, which is 20 lbs heavier than the previous model. The chassis is now more rigid which results in the virtual elimination of chassis induced resonances. The MK. II now utilizes 6 ceramic isolating feet to stabilize the unit.

3. The standard supplied 211 tubes will now be the exceptional Shuguang Pevane. They represent a marked sonic improvement over the previously supplied standard Shuguang. The Pevane is also more durable and reliable and runs 15% cooler.

4. AC ground lift is now included. This switch conveniently eliminates hum created by AC ground loops.

The MK. II Dragon is now the finest sounding, high power amplifier in existence. Its purity is within a hair's breath of the finest SET 300B amplifiers (the Frankensteins) yet its power delivery is awe inspiring. It also runs cooler and is exceptionally quiet.

The purity, transparency and continuousness of a DHT SET but with the power, explosive dynamics, weight and impact of a huge push pull pentode amplifier - sounds mutually exclusive, not any longer. The 211PP Dragon mono amplifiers are such a creation. These amplifiers are absolute state of the art in terms of components selected, circuit design and execution and construction quality. This is unique among high power, push pull DHT triode amplifiers. There has never been a high power, DHT amplifier built to this standard with sonic performance at this level. The Dragons are capable of driving even the most difficult speaker loads.

Features include:

• The finest 6N copper interstage, output and dual power transformers
  
• No coupling caps in the signal path
• Tube compliment- 6EM7 super tube for input- So much current capability it has its own power supply
• 300B Driver Tube for utmost purity ( no pentode tubes used in this DHT design)
• Dual 211 Shuguang Pevane output tubes in a push pull configuration which dramatically lowers distortion and provides huge power reserves. (over 120 watts of peak power- 80 watts continuous- sounds more like 150 watts)
• Teflon caps use in cathode bias circuit
• Power supply caps are all 1500V polypropylenes
• Highest quality discrete resistor potentiometer permit the direct connection of a CD player thereby obviating the need for an expensive line stage
• Binding posts are Coincident 6N copper, .25" solid post
• Auto bias
• All resisters, red metal film, 1% and none less than 2 watts
• All meticulously hard wired
  

 

211pp Dragon MK. II Mono Amp
Output Power: 75w (Triode) / Push-Pull Class A
Output Impedance: 8ohm,16ohm
Frequency Response: 20hz-20khz ±1db
T.H.D.: <1%, 20hz-20khz (Ref. Output)
Input Sensitivity: 1v
Input Impedance: 100kohm (Rca)
S/N: >90db 
Tubes: (6EM7×1, 300B×1, 211×2) / Channel
Power Requirement: Ac 115v Or 230v±5% 50/60hz (Selectable)
Dimension: 270 W x 189 H x 520 D (mm) 
Gross Weight: 41 Kgs
Net Weight: 38.5 Kgs

Price:
$10999 US /pr. includes freight.
$ 9999 US/pr. when purchased with any Coincident speaker.

 

Coincident's Reference System:

Featuring Double Pure Reference Extremes

"This system points out some significant flaws in my own. I would like to adopt it as
My Reference in Absentia. Listening to my familiar music on CDs and your LPs had a profound impact I will be processing the experience for quite some time, I expect.

Quite simply- it was incredible.
Thank you, Israel."

Rick Becker- enjoythemusic.com

 

Statement MC Step Up Transformer

Coincident set out to design and create the finest moving coil step up transformer ever made. This was not meant to be a good value product or simply another alternative to amplifying the low level signal of a moving coil cartridge. It had to be purer, more transparent with lower noise and distortion and provide sufficient gain so that the performance of the best cartridges would be realized. The result is the Statement.

It utilizes the finest 6N copper transformers with steel and iron shielding so that it is impervious to noise, hum and RFI. Bandwith is 10 hz - 25khz with no possibility of signal saturation.The case is fabricated out of the same stainless steel mirror finish of the Statement Phono and Line Stages which adds more shielding and total rigidity. The internal moving coil transformers of the Statement Phono Preamp are identical to the Statement MC Step Up except for the fact that they are set at 20 db of gain and cannot be changed to 26 db.

The Statement offers 20 db or 26 db gain options and four adjustable impedance settings. Any impedance setting can be internally incorporated.

If the goal is to hear the ultimate performance of your chosen moving coil cartridge, the Coincident Statement MC Step Up Transformer must be your choice. In order to maintain its reasonable price given its high cost of manufacture, Coincident is offering the Statement only on a direct to consumer basis. If it were to go through traditional dealer networks, its selling price would be doubled.

Specifications:

Gain: 20dB or 26 db (internally adjustable)
Input impedance: 3-10, 11-30,31-100,101-300- Can be changed to customer's specific request.
Output impedance: 47k ohm
Frequency response: 20Hz to 20kHz(±0.2dB)
Channel balance: ＜0.1dB
Channel separation: ＞90dB
Shielding: permalloy +silicon steel + soft iron
Dimensions: 203 mm x 260 mm x 390 mm.
Weight: 28 lbs.
Price: $2499 US

 

 

NOW ADDED TO CLASS A MOVING COIL STEP-UP DEVICES

COINCIDENT STATEMENT M/C TRANSFORMER -
by www.high-endaudio.com

The Coincident Statement is now the finest MC step-up I've ever heard, of any type. The discovery of a new reference component is always a cause for a "celebration", though, in this case, it will have to be tempered. This is because the Coincident's degree of superiority over the former reference, the Bent Audio Silver, is quite subtle. In fact, to even initially hear the differences took numerous A/B/A/B comparisons (after basic A/B comparisons failed for me).

Read full review at www.high-endaudio.com

 

 

COINCIDENT PURE REFERENCE "EXTREME"
by www.high-endaudio.com

The "Extreme" is simply the "Original" Pure Reference, with the exact same drivers and crossovers, but in two separate cabinets (a mini-monitor and a subwoofer), instead of one large floorstander. With the monitor sitting directly on top of the subwoofer (at the front), the Extreme is around 12" shorter, though its subwoofer takes up around 50% more floor space, because it is 4" wider. The price for the Extreme is $ 26,000, compared to $ 22,000 for the Original.

Read full review at www.high-endaudio.com

 

 

 

Passive vs Active Preamps

Passive Preamp- In essence is merely a volume control designed to attenuate the signal going from the source (usually a CD player) to the amplifier. Since it is passive, it has no inherent gain because it has no active components (tubes or transistors) in the signal path.

The quality (sonic purity) will be largely dependant on the volume potentiometer used. The finest discrete resistor pots will sound more accurate than a variable one, for example, since the signal travels through only one resistor at any given setting and is therefore not dependant on volume position as is the case with a variable pot. Many believe that transformer volume controls can be superior to even the best discrete resistor pots, since the TVC is inherently passive while the latter still requires the audio signal to traverse a resistor. The TVC is more costly to properly implement since the best transformers are very expensive.

Type, length and quality of the internal wire will also affect the sound as will the connectors being used. The inclusion of a selector switch will compromise the ultimate transparency of the sound to a greater or lesser degree compared to a passive eschewing this switch.

Active Preamp- Not only controls the volume of the source component but since it uses active devices (tubes or transistors) in the signal path it has gain. The active preamp inherently has many components in the signal path compared to a passive. It uses all the components of the passive with the addition of a power supply, capacitors, resistors, gain devices, and means by which all these parts are connected.

Logic would seem to dictate that the active preamp must adulterate the signal to a far greater degree than the passive by virtue of all those additional components.Further, since the active has the additional disadvantage of requiring a power source, tubes or transistors it must not only impose far greater noise, it is also more costly and inconvenient to use. Why would anyone want to use the active in a system? Theoretically, it would seem nonsensical to use anything but a passive preamp.

The Imposition of the Real World –

Passive Preamp - While it is inherently simpler in design with no active components in the signal path, it is highly susceptible to component interaction. The affects of the IC cable (impedance, capacitance and resistance), the source resistance which is the combination of the potentiometer and the actual source and the input impedance of the amplifier are all critically important in potentially altering the audio signal from source to the ultimate sound being heard.

The length of the cables between the source and passive and then to the amplifier must be strictly attended to. Too long a cable and roll offs at both frequency extremes will occur. Impedances between the volume control and the imput impedance of the amplifier must be compatible in order to avoid sonic degradation. Furthermore, since a passive has no gain, the output voltage of the source component must be sufficient and the amplifier and the speakers need to be of high sensitivity or not enough ultimate volume can be achieved.

The purest, simplest but admittedly most inconvenient method of passive attenuation is to have discrete resistor pots installed at the amplifier input. This method avoids the extra cable interaction and achieves the desired amplifier input impedance.

To summarize, in order for a passive preamp to work properly the following conditions must be met:

1. Source component must have sufficient ouput voltages;
2. Short, low capacitance cables must be used between the source to the passive and from passive to the amplifier;
3. Output impedance of the passive's volume pot should be low (less than 25k) while the input impedance of the amplifier should be sigificantly higher (100k);
4. Amplifier's input sensitivity should be high (minimum of .75v for full output).
5. Speakers should be high sensitivity (minimum of 90db).

If even one of the above conditions is not adhered to, passives will offer highly compromised sonics. However, when all of the above conditions are met, there are very few active preamps on the market that will yield better sound overall. For an active to provide superior sound, will require an amazing unit designed and executed to the highest level. (translation- it will not be cheap- but do not confuse excessive price with high performance- however high performance will be expensive).

Active Preamps - Due to the use of a myriad of components in the signal path, most active preamps severely color the sound. The signal entering them rarely resembles the sound exiting them. Theoretically, an active preamp should emulate a straight wire with gain. It should be as pure and transparent as the finest passives in an optimized system yet offer the benefits of gain and nonsusceptibility to component or cable interaction. This task would seem impossible to fully achieve and arguably no active preamp currently available has been completely successful in its accomplishment. The realistic goal of an active preamp is to provide sound with all the advantages inherent in the design with drawbacks that are so minor as to wither into insignificance when viewed in its totality. Achieving this objective requires the following:

1. The finest passive and active components available connected with the shortest signal paths possible;
2. A power supply that is impervious to voltage fluctuation or current demands;
3. The finest form of signal attenuation;
4. The purest gain devices;
5. Low output impedance;
6. A highly rigid chassis that is not prone to resonances.

The inherent practical advantages of an active over a passive is that due to output buffering, interaction between the source, connecting cables and amplifier input impedance ceases to be an issue. Further, due to added gain, much greater flexibility in system assembly is possible.

The other huge advantage presented by an active line stage is that it amplifies the source signal to a higher level, unlike a passive design which has no gain, so that the power amplifier is able to more accurately pass this signal to the speakers. This is similar to what occurs when inserting a moving coil transformer or head amp into a low gain phono stage. The low level cartridge signal becomes amplified so that the phono preamp can transmit this incoming signal more accurately to the amplifier. While the system now has an extra component in the signal path which would intuitively create the impression that purity would be compromised, the opposite results- greater fidelity is achieved. Not only is the sound more dynamic, harmonically more complete with superior rendering of the frequency extremes, there is a noticeable enhancement in detail retrieval.

Coincident has up to the advent of our Statement Line Stage recommended the use of the best passives when all the system conditions were optimized. The sonic compromise inherent with all previously auditioned active units in terms of imposed colorations were too obtrusive to ignore, despite their other advantages.

Coincident Statement Line Stage -

All the requirements mentioned above to create the superior active preamp have been met. The end result is an active line stage that is virtually as pure and transparent as not only the best passives but as accurate as going directly from the source component to the amplifier using the finest 1m interconnect. The sonic leap in dynamics, weight, impact and punch as well as full extension at both frequency extremes is dramatic.
The enhancement of musical enjoyment wrought by the insertion of the Coincident Statement Line Stage into an audio system is of enormous proportion. As reviewers and owners of the unit have confirmed, the superiority of the Coincident over passives and existing active preamps is not subtle. A short audition is all that is required to hear this level of advancement.

 

300B Tubes For Frankenstein Amplifiers

The Coincident M300B Frankenstein amplifiers are supplied with Electro Harmonix 300B Gold Grid tubes. At their price, they offer very good sonics from top to bottom and have proven themselves to be quite reliable. There are other 300Bs available and if tube rolling is appealing feel free to try experimenting. Our advice, after years of experience with 300Bs in the Frankensteins is as follows:

The finest 300B available is the Shuguang Treasure Black Bottle. Not only are the sonics the best we have heard, we have not experienced a single failure in the field. We have not heard a superior sounding tube, nor one that is more reliable. Coincident supplies matched and tested pairs.

We are hesitant to recommend any of the mesh plate 300Bs since they tend to be prone to microphonics due to the inherent resonant nature of their internal structure. We also have stopped recommending KR 300Bs, despite their superb sound, due to their poor reliability and the manufacturer's reluctance to honor their warranty.

If anyone has any questions or comments about 300B tubes in the Frankenstein amplifiers, feel free to contact us.

 

 

VIDEOHIFI interviews Coincident Speaker's Israel Blume

Coincident Speaker Technology is proud to still state that unlike the majority of current speaker companies (i.e. Revel, Aerial, Von Schweikert, Red Rose etc.) all its speaker models are designed and completely manufactured in Canada.

All the crossovers are meticulously hand soldered in Canada, matched to within 1% tolerances using the finest Canadian and American components. Coincident does not use poor quality Asian sourced crossovers that are pre built and cost a couple of dollars. The price of one capacitor used in a Coincident speaker crossover exceeds the cost of these entire crossovers that are finding there way into very expensive competing speakers.

All internal wiring is manufactured in Canada using American 6N copper. Only the finest Canadian dielectrics like polypropylene and air Teflon are used. Our wire sounds the best and is very expensive to manufacture and labor intensive to terminate. Other high end speaker companies use off shore cable that is sonically inferior and costs pennies.

All Coincident speaker enclosures are meticulously CNC and hand crafted at our facilities in Canada. Only the highest quality Canadian made hardwood MDF using furniture grade cherry wood veneer which is pressure applied on both sides of the board is utilized. Having our enclosures made in China, as most other speaker manufacturers, would save 80%-90% of the cost. However, we would not even think of doing this since the quality of workmanship simply does not compare. Inspect a Coincident enclosure with those made in China and the difference is painfully obvious. Coincident will never sacrifice quality for profits.

All the drivers of Coincident speakers are sourced from only state of the art manufacturers such as Scanspeak, Vifa and SEAS. Coincident does not use any Chinese manufactured drive units that are knock offs of the above noted brands. Many high end speaker companies no longer use the expensive, best sounding drive units made by these European companies, instead opting to use inferior sounding and incredibly cheap (costing as little as a couple of dollars) Chinese units that are almost visually identical. The consumer is fooled into believing he is buying an expensive speaker using Scanspeak drivers when in reality the drivers are very cheap poor quality units that only physically resemble those drivers.

Coincident Speaker Technology is committed to providing the high end audiophile the finest value loudspeakers in the world. Coincident, therefore, will NEVER sacrifice quality. No detail is considered too trivial if it enhances the sonics or build quality of our speakers. Coincident will never offer an inferior product in pursuit of greater profits. Therefore, none of our speakers will be made in China nor will any of our models use inferior components because they are inexpensive to purchase and will increase our profit margins at the expense of quality. Coincident speakers exist for only one purpose: to provide the discerning music lover with the finest sounding, best built loudspeakers available anywhere near their selling price.

 

Why Biwire?

Biwiring is when a loudspeaker has separate connections to the bass and the treble/midrange. The idea is to use individual speaker cables to each section. Besides being profitable to cable manufacturers, since the user is required to purchase double the amount of speaker wire, are there any sonic benefits to this arrangement?

The answer is yes and no. Yes it is a benefit for loudspeakers that are not properly designed. In speakers where the crossover sections are interdependant and not adequately isolated from one another, biwiring will likely offer a sonic benefit. However, in speakers, (like all Coincident models), that have all the crossover sections, (high pass, low pass etc), completely separated and isolated from one another and are run to the binding posts, (as opposed to being interconnected between sections and wiring all the hots and grounds to the speaker's binding posts), biwiring affords NO sonic advantage and may actually involve a sonic degradation depending upon the speaker cable used.

Coincident recommends biwiring only in those cases where a consumer has the intention of biamping his speakers. A biwiring option will be necessary if one is biamping a system, meaning separate amplifiers will be powering different drivers. Otherwise, biwiring is not only totally unnecessary and a waste of money, but a pain in the derriere.

Mirror Imaged Side Firing Woofers - Advantages

Unlike the majority of other speaker companies that place their woofers on the front of their speakers, Coincident mounts their woofers on the side of the enclosures in a mirror imaged configuration.This is done because there are 3 distinct advantages with NO downside.
TOP

1. Elimination of Diffraction Effects -

Since the largest drivers,(the woofers), are mounted on the side of the enclosure, the front baffle can be made as narrow as the smaller midrange drivers, thereby eliminating diffraction effects, (which are responsible for impairing image width and creating high frequency smearing).

2. Flexibility of Speaker Placement -

Because the side firing woofers are mirror imaged, there are two positions to avoid room standing waves - woofers aiming to the inside or to the outside. In a room devoid of standing waves, (a very rare phenomenon), there would be absolutely no sonic difference whether the woofers were firing inside or outside, (so long as there is sufficient distance to the side wall in the case of outside firing). This is so because the crossover frequency to the woofers is so low, (typically 125 hz), where the wavelengths are very long, (in the range of 9 ft). This means that the woofers can be placed a distance as much as 9 ft away from the midrange units and still achieve seamless driver integration.

The Stereophile Show 2001 provides a dramatic real world illustration of the benefits of mirror imaged side firing woofers. The demonstration rooms were plagued with a standing wave centered at 100 hz ( elevated in amplitude by 12db!). This was the case when the Total Eclipse woofers were firing to the outside and as other exhibitors experienced, when the woofers were front facing . However, when the woofers aimed to fire to the inside, the room standing wave was avoided and flat frequency response to below 30 hz was achieved.

3. Simulation of Steep Crossover Slope-

Since high frequencies are directional, (low frequencies are not), aiming the woofers to the side of the listening position causes out of band high frequency information to be attenuated, thereby simulating an acoustical high pass filter. Therefore, the electrical first order crossover (chosen for reasons of purity and phase coherency- attenuates out of band frequencies at a rate of 6db per octave), of Coincident speakers act more like an acoustical third order slope (with its advantages of steeper attenuation- 18db per octave- of unwanted out of band high frequencies), but with no sonic penalty since no additional electrical components are added to the signal path.

Amplifier Power - How Much Is Enough?

This is a question that is asked almost more frequently than any other.As with most issues in audio,the answer is complex and depends upon the following:

1. Speakers being used- Sensitivity and the impedance curve being critical.

2. Personal preferences of the listener- Type of music listened to and at what output levels.

3. Size of room - To fill a larger room will take proportionally greater amplifier power.

Speakers-
Acoustical output is dependant upon the power of the amplifier used and the efficiency with which the speaker being driven can transform the electrical signal into sound.The term "sensitivity" is a speaker measurement that reveals how much sound (in decibels) is produced at a specified distance, (usually 1 meter), from the speaker when it is fed a specified input signal, (usually 2.83 volts which is equivalent to 1 watt into 8 ohms). Therefore, a more sensitive speaker that has a flat, benign impedance curve (of 8 ohms or more), will produce greater acoustical output with the same specified amplifier power than a less sensitive speaker or an equally sensitive speaker that has a reactive, low impedance modulus. For example, a speaker that is 3 db more sensitive than another will require only half the amplifier power to generate the same sound output.

If a speaker has a sensitivity rating of 85 db @1 watt - 1 meter, to achieve an output of 88 db would require double the amplifier power or 2 watts.91 db output would take 4 watts. For 100 db output of sound, would require 32 watts of power. And if this speaker was rated at 4 ohms, a 64 watt amplifier would be needed to produce 100 db.

By contrast, a 94 db sensitive speaker would require only 4 watts to achieve a 100 db output level. Since most listening in the home environment is undertaken at 85 db or less, it can be clearly seen that only a fraction of a single watt of amplifier power is all that is required for the vast majority of listening. A 100 db output, which is loud, still needs only 4 watts of power to attain. However, it must be emphasized that while listening at an average level of 100 db, during musical passages that are very dynamic with lots of low bass content, many hundreds of watts may be necessary, (albeit for only the duration of a millesecond), to avoid amplifier clipping.

The above example clearly demonstrates how significant the sensitivity and impedance curve of the loudspeaker is upon determining how much amplifier power is necessary.

Personal Preferences of the Listener-

As the above example illustrated, higher listening levels requires greater amplifier power. Therefore, the output levels the listener chooses to listen at, will be critical in determining the amount of power that will be satisfying. The listener who is content at levels of 80 db will need a fraction of a watt while someone who likes to listen at 105 db will be using almost 260 times more power!

Of equal importance is the type of music enjoyed. Full orchestral music, for example, is very demanding on amplifier power in order to reproduce the exceptionally high levels of dynamics coupled with very low bass content (which uses enormous amounts of power). Conversely, chamber music, light folk etc. is usually listened to at lower SPLs and its musical content requires far less amplifier power to accurately reproduce.

Furthermore, some listeners prefer a punchier, gutsier sound presentation than others whose priorities lie more in the area of detail retrieval, imaging etc. For some, visceral impact is mandatory or at least may represent much more of a priority than it is to others. These personal predilections must be factored into the equation of how much power is sufficient.

Room Size -

All things being equal, the larger the room, the more amplifier power required to fill it. The sensitivity rating of a speaker is the measurement of acoustical output at a distance of 1 meter. The further away the listener is from the speaker, the lower the sensitivity. Therefore, a speaker producing 94 db from 1 watt of amplifier power at a distance of 1 meter will produce less sound pressure when the listener is 2 meters away. For a speaker to energize a room of 1000 cubic feet, for example will require significantly less amplifier power than to do the same in a 2000 cubic foot space. As a real world example, at the recent 2001 CES, Coincident demonstrated in a hotel suite of 1872 cubic feet using a 24 watt amplifier. To achieve similiar sound pressure levels and bass impact in another space of 7200 cubic feet, required 3x the amplifier power.With the same 24 watt amplifier in the much larger room, the sound was not as weighty, impactful or as dynamic as it was in the aforementioned smaller environment.

Conclusion-

With easy to drive speakers, like Coincident, many are afforded the opportunity of using low powered amplifiers like SETs with completely satisfying results. For those in a compact room, who listen at moderate levels to jazz , light rock, folk etc, then the inherent superiority of the best SETs will be appreciated. That is not to suggest that SETs are for everyone.They are decidely not. If your musical tastes are focused on big orchestral music, heavy rock, etc., and you listen at high spls in a large listening space, then small tube amplifiers may not be your sonic cup of tea. It would be recommended that a more robust amplifier be used.

Loudspeaker Impedance And Amplifier Matching
06/29/01

Solid State Amplifiers:
With transistor amplifiers ,the amp's output impedance is never matched to the load it drives.The lower the load impedance ,the closer it comes to a true impedance match , because the output impedance of a solid state amp is very low - typically a fraction of an ohm.This helps explain why (all things being equal- and the amplifier has sufficient current capability)4 ohm speakers produce greater acoustical output than 8 ohm speakers.The lower impedance speaker offers less resistance to current from the amp.The transistor amp sees less resistance into 4 ohms , therefore its output stage delivers more current.

Tube Amplifiers:
A tube amplifier's output stage(s) are totally different. A true match between the load impedance and the plate impedance ( or plate - plate impedance of a push - pull tube output stage) is never absolutely possible.The tube's plate impedance is typically exceptionally high
( thousands of ohms.) Therefore ,even a tube output transformer ( which becomes necessary to lower the plate impedance so that a typical speaker can be driven) with a primary impedance of 3K - 8K ohms will not closely approach this match. Therefore, it can be seen that the operation of tube versus solid state outputs is reversed. In the case of transistors, impedances cannot be matched due to the ultra low output impedance of the amp ,while with tubes, the match cannot be achieved because of the very high output impedances.

The output transformer in a tube amp lowers its impedance to a level where speakers can be made to operate and extract power from the driving amplifier. The output transformer is designed with a given ratio between the number of turns of wire in the primary and a nominal secondary impedance. For example, if we connect an 8 ohm loudspeaker to an amplifier with a primary impedance of say, 5,000 ohms and a transformer tap of 8 ohms, the primary impedance remains at 5,000 ohms and the amplifier delivers a given amount of electrical power. But ,if a 4 ohm speaker is connected to this amplifier, the output volume will diminish because the 4 ohm load causes a reduction of the primary winding impedance. This reduction means the amp's output transformer presents a poorer match to the plates of the tube output stage than it previously did.

On the other hand, if a 14 ohm loudspeaker is connected to the same 8 ohm tap, the primary winding's impedance is increased. The transformer represents only a ratio of turns and its impedance is determined by the load connected to it. Because the transformer's impedance has increased, it comes closer to matching that of the plate circuit. The result is greater output volume from the speaker.

In conclusion, a tube amplifier will produce more output ( greater voltage delivery) into higher impedance loads. Therefore , a 14 ohm speaker will be much more efficiently driven by a tube amplifier than will a 8 or 4 ohm speaker. This becomes of critical importance when using OTL or single ended triode tube amplifiers when available output power is low and amplifier output impedance is very high.

Available Options for Coincident Speakers