MODEL 5
The Model 5 amplifier once again reveals the excellent value of an Avantgarde Acoustic hornspeaker. Considering that most other speakers will necessarily require heavy follow-up investments in adequate amplification, the Model 5 amplifier and an Avantgarde Acoustic hornspeaker will make an outstanding combination at the respective budget sum. In addition, Model 5 offers innovative technological features. The consequent elaboration of the principle „less is more“ led to an ultra short signal path and a very small feedback loop with only 2 amplification stages. This preserves the music‘s original dynamics and provides a well balanced, highly resolved and precisely focussed, yet unobtrusive reproduction. There is barely another amplifier on the market featuring less active parts in the signal path and it may be hard to believe, but despite its little nominal power, Model 5 delivers a soundstage of truly unbelievable authority, including even the lowest octaves. Simply a perfectly balanced amplification matching any high quality speaker system. www.avantgarde-acoustic.de
Page
1
MODEL 5 MAXIMUM PERFORMANCE FOR THE MONEY Avantgarde Acoustic, the highly respected manufacturer of exclusive spherical horn systems have ventured into the lion’s den and now offers for the first time a high end integrated amplifier within their product portfolio. A speaker specialist designing and manufacturing their own electronics? A closer look this new project shows a well thoughtout, coherent and most of all customer friendly concept.
good match with a horn. Like a big Diesel truck engine might be ideal to pull a 30-ton load, but in a racing car, it would certainly be the wrong choice.
Horn loudspeakers are not only characterized by their extreme sensitivity and dynamics, but sometimes behave with all the agility of a flowering mimosa. It is true that due to their high impedance, the horn systems from Lautertal in Germany are very simple to drive. They represent an easy load for any amplifier, but their incredible resolution of fine detail quickly reveals the limits of many highly praised amplification. It is like in real life: for a good sound you have to combine what is a good match. An amplifier, which sounds great on a power demanding speaker system, will not necessarily be a
“I have never excepted that horn customers have to spend a lot of money for features, they actually do not need. It was our clear goal to concentrate on the essentials and design a simple but perfect amplifier for high sensitivity speakers. No unnecessary ballast like a big power supply or oversized transformers and numerous transistors. Maximum performance for the money!“ explains Holger Fromme, managing director of Avantgarde Acoustic.
The classical virtues of any amplifier “all things to all men” attach great importance to – output power, load stability, damping factor etc are of no circumstantial significance for a horn speaker system. With a horn, quality is simply more important than quantity.
Based on these considerations Avantgarde Acoustic has invested in a significant research
and development program to realize a unique amplifier concept. The MODEL5 is a special integrated amplifier, which ideally matches their ultra dynamic speaker systems. With surprisingly simple means, the well-known virtues of their horns – dynamics, resolution of fine detail and coherency are emphasized and brought to life. In this respect the horn specialist from Lautertal have made a courageous and most of all consequential step towards further perfecting their sound systems. Courageous because no other electronic manufacturer wanted to think about what’s really needed with the sensitive and revealing Avantgarde Acoustic hornspeakers. Consequential because a new benchmark in performance - and in affordability - is now available. Now the music lover can buy a perfectly balanced amplifier for their horn system - no “TRIAL & ERROR” when searching for the perfect sound combination, but simply “PLUG & PLAY”.
www.avantgarde-acoustic.de
Page
2
MODEL 5 “I admit it. We have purposely played the trump card of our high impedance and high sensitivity horns, because in combination with the MODEL5 we managed to achieve a sound quality at a price which is simply unbeatable when compared to normal speakers and amplifiers” states Holger Fromme. In the following pages the special technical features of the Avantgarde Acoustic MODEL5 amplifier are explained. CLASS A MODE The MODEL5 is an integrated transistor push pull amplifier with a power output of 2 x 0.4 watts at 8 ohm in pure CLASS A mode. At 20 ohms 1.1 watts is available in CLASS A before the amplifier converts to CLASS AB mode. Thus Avantgarde Acoustic consequently continuous its high impedance technology with all its advantages first introduced in the TRIOΩ OMEGA model. By increasing the bias current the CLASS A mode eliminates distortions when the signal passes the null point of the signal curve in push-pull amplifiers. The high sensitivity of the Avantgarde Acoustic horn systems ensure even at this low power output, that up to 103 dB with the DUO and up to 110 dB with the TRIOΩ the amp works in this optimal CLASS A mode. Above this power the MODEL5 amplifier operates in CLASS AB mode. The output power now increases to 2 x 27 watts at 8 ohms, and in combination with the UNO, DUO and TRIOΩ this is enough power to really get
“rolling”. If the DUO is connected to the MODEL5 this will translate into an incredible 118 dB sound pressure level. This clearly shows that the combination, even when connected to a small power amplifier is playing in another league. Small power and CLASS A mode spontaneously gives you the subjective impression that this small amplifier should be a perfectly match with dynamic horn speakers. Matthias Ruff, the spiritual father of the MODEL5 amplifier quickly concludes: “Small power output and a high bias voltage are on their own no guaranty for a good sound. These are just simple engineering tools to further optimize the sound.” The resultant sound is the combination of all components, and this always includes the speakers. “How many amplifiers exist, which measure perfectly when connected to a dummy loudspeaker load in the laboratory, but when hooked to a real speaker they simply sound bad.” According to the chief designer of Avantgarde Acoustic, the reason can be found in the forces which flow back from the speakers voice coil into the amplifier. With every movement of the voice coil, magnetic field currents are induced which are fed back to the amplifier. These are called “Electro-MagneticForces” (EMF). Ideally the amplifier should “suppress” these forces and control the speaker in every situation. In common amplifier designs one tries to control these forces with a high www.avantgarde-acoustic.de
Page
3
MODEL 5 damping factor. With high feedback the output impedance is reduced and the damping factor is maximized.
cordingly. Distortions are effectively eliminated and at the same time a high damping factor is achieved.
TYPICAL PUSH-PULL TRANSISTOR AMPLIFIER The control of these ElectroMagnetic-Forces is difficult to achieve. To better comprehend the problems, one needs to understand the operation of a typical transistor PUSH-PULL amplifier. The respective graphic shows the typical layout of a transistor amplifier.
Simply spoken HGHF-amplifiers use the headroom generated by the excessive high open loop gain to later correct the “errors” at the output (i.e. distortions etc.) with the feedback. HGHFamplifiers thus in general have very good technical specifications. “Superb technical measurements in the laboratory are no indication for good sound.” responds Matthias Ruff angrily. “Static dummy loads are not speaker systems and fixed frequencies of an oscillator are not music! People naively believe in the specs of the data sheets and are totally surprised when at home it does not work.”
To achieve outstanding technical specifications, the vast majority of all PUSH-PULL amplifiers are usually designed according to the “High Open Loop Gain” concept. In this concept the open loop gain of the amplifier is set very high and the overall signal gain is later reduced to the desired level by applying very high levels of feedback. The intention of this circuit design is to sub sequentially reduce distortions and increase the damping factor of the amplifier. This “HIGH GAIN High Feedback” concept (HGHF) in principle is very easy to implement and at first sight, very logical. By using several amplification stages the input signal is first amplified to a level higher than in actual fact needed. This excessive signal level is then sub sequentially reduced to the required value by a high feedback loop. Feedback continuously compares the amplified output signal of the amplifier with the input signal, if it detects deviations, the feedback corrects ac-
The HGHF-principle is plausible in theory, but in practical operation generates new distortions. To better understand one has to take a closer look at the circuit design of an amplifier. An amplifier in general has the func-
tion to amplify the input signal (for example: from a CD-player) through several stages successively up to a level, which is sufficient to drive a speaker system. To achieve a high signal gain in HFHF-amps several sequential amplifier stages are used. Most modern high performance amplifiers use as many as seven cascaded stages. In addition the input signal does not only have to pass through several serial amplifier stages but most of the amplifiers use several power transistors in parallel to achieve a higher power output. In some “monster” amplifier designs up to 20 power transistors are switched in parallel. Serial and parallel signal processing have two major disadvantages. First of all any transistor - even highest-grade versions produce distortions. The more stages are used, the higher the distortions of the circuitry become. And theses “distortions” do not only add to each other, but multiply
NORMAL AMPLIFIER SERIAL AMPLIFICATION STAGES AMP
AMP
AMP
AMP
AMP
AMP
AMP AMP
PARALLEL POWER TRANSISTORS FEEDBACK LOOP
AMP
GAIN
HIGH FEEDBACK
REQUIRED AMPLIFICATION LEVEL
INPUT LEVEL
HIGH OPEN LOOP CONCEPT GRAFIK TRANSISTOR AMPLIFIER
www.avantgarde-acoustic.de
Page
4
MODEL 5 together as well. This is because every stage amplifies the distortions of the previous stage and modulates its own distortions on top of it! The second problem refers to the speed in which the feedback readjusts the problems at the output. The more stages an amplifier has, the slower the “forward” processing of the signal is, and the bigger the lateral off-set between the input and the output of the amplifier becomes. In practice this is called “slow forward amplification”. In the laboratory, distortion occurring during the amplification of the signal can be eliminated with a high feedback, but these corrections only become active due to the slow forward amplification with a subsequent time delay. This is to say that the corrections do happen with inertia and thus probably at a moment in which the original distortion has already disappeared. The attached graphics show these correlations. Graphic 1 shows a typical EMF distortion curve (blue) of an amplifier. If the feedback has no delay (red curve) all distortions are effectively eliminated. The resulting output will be a perfectly linear frequency curve (yellow curve = blue + red curve). Graphic 2 and 3 show the same constellation, but this time with a time delay of the feedback loop. Already with a small delay, the feedback circuitry only manages to reduce the distortions slightly, but at the same time generates a higher frequent distortion pattern
FEEDBACK WITH NO DELAY
NO DELAY
EMF DISTORTIONS
FEEDBACK + DELAY 0
RESULT
GRAPHIC 1
SMALL FEEDBACK DELAY
DELAY
EMF DISTORTIONS
FEEDBACK + DELAY 1
RESULT
GRAPHIC 2
DELAY
HIGH FEEDBACK DELAY
EMF DISTORTIONS
FEEDBACK + DELAY 3
RESULT
GRAPHIC 3
itself (graphic 2, yellow curve). The bigger the delay of the feedback circuitry (graphic 3), the less the original distortions are reduced and the more new distortions are added, which even more important have a lower frequency pattern (yellow curve). Normally high frequency distortions beyond the audible bandwidth are hardly detectable. Contrary to this, high feedback
delay distortions occur in a lower frequency band and cause a “coarse grain” reproduction of the high frequencies (graphic 4, page 6). In the previous graphics the distortions have been monitored exclusively in isolation. But what is the effect of these induced feedback distortions on the music signal? In the following, the distortion pattern from graphic 2
www.avantgarde-acoustic.de
Page
5
MODEL 5
In this case with only small delay distortions, the output signal is more or less identical to the input signal, as the amplitude of the music signal is much higher than the induced distortions. The curve pattern is slightly sharper and only minimal phase shift does occur (yellow curve shifted sideways from blue curve). With the higher feedback delay distortions in graphic 6 the phase is significantly shifted. Some frequencies will be blurred, the high frequency band will be bumpy and the staging of the music reproduction will be drastically reduced. The feedback thus generates an inevitable new distortion, which is again amplified by the forward processing and is again corrected by the feedback etc. etc. The delay between the start and the elimination of the problem permanently generates new distortions. The amplifier gets into a stage of permanent oscillation and has more work fixing itself generated problems than with processing the original signal. Fortunately these self-produced distortions are mostly of linear nature. This is to say that the amplifier circuit corrects the same distortion all over again, regardless of the music signal. The described time delay when
FREQUENCY RESPONSE
NORMAL AMPLIFIER
TIME / FREQUENCY
MODEL 5 FREQUENCY RESPONSE
and 3 are modulated onto a music sine wave. Graphic 5 shows the original music signal (blue curve), the feedback distortions resulting from a small feedback delay (red curve = yellow curve from graphic 2) and the resulting output signal (yellow curve).
TIME / FREQUENCY
GRAPHIC 4
MUSIC SIGNAL WITH SMALL FEEDBACK DELAY
MUSIC SIGNAL
DELAY DISTORTIONS 1
RESULT
GRAPHIC 5
MUSIC SIGNAL WITH HIGH FEEDBACK DELAY
PHASE SHIFT MUSIC SIGNAL
DELAY DISTORTIONS 3
RESULT
GRAPHIC 6
correcting these self produced linear distortions, in practical operation is, subjectively not so critical. Contrary to above, this problem is much more serious with a speaker connected, e.g. a varying complex load. Any speaker system is an unknown, variable disturbance which is continuously inducing interferences into the amplifier. These electro-
magnetic-forces are induced by electrical currents of the speaker drivers and these are fed back to the amplifier as variable error voltages. The feedback detects these error voltages and tries to eliminate them. As these electromagnetic-forces permanently change with frequency and level of the music, the correction occurs with a time delay, so the correction will logically always be too late. For an experienced
www.avantgarde-acoustic.de
Page
6
MODEL 5 listener it is relatively easy to distinguish between the relatively harmless self-generated amplifier distortions and feedback distortions induced by the speaker. Mostly in operation this problem shows up as a “slow”, sometimes “hard” midrange/treble response and a reduced resolution of the system. Furthermore the delay of the feedback will cause a permanent shifting of the phase of the signal, which shows up as harmonic distortions. This results in a “specific” tonality of the amplifier with reduced sound staging and naturalness of the sound. THE PHILOSOPHY Avantgarde Acoustic loudspeakers are known to react very quickly to any variation of the music signal and to transform these into audible sound. “With our speakers we use the horn technology to make the forward acceleration and transient response as fast as possible. What goes in, should come out,” describes Matthias Ruff. Different to most manufacturers who op-
timize the decay time of their speakers (waterfall diagram) the company from Lautertal regard the fast forward signal processing as the main advantage of their speaker designs. “Who cares about the second distortion, if the first distortion has not even been detected. Most speakers are purposely made slow and inert, only to make the waterfall graphs look good in reviews. It is so obvious: the less I let pass through from the front, the better it looks from behind. But this doesn’t mean that you have a good speaker. It is like reducing the maximum speed of car drastically only to improve the breaking distance.” explains the Avantgarde designer furiously. And with multi-stage amplifiers having high forward gain and strong feedback Matthias Ruff is seeing the same problems. “In the HGHF-principle you purposely put up with errors during the forward amplification, because later at the end you can flatten everything with a high
feedback”. In other words these designers do not even try to prevent distortion in the early gain stages, but count on heavy reprocessing of the signal at the end. “If I already falsify the signal at the front end, I can later correct as much as I want, the information simply gets irretrievably lost”. In combination to the concept of their speaker systems Avantgarde Acoustic clearly focuses as well on their amplifier to optimize the forward signal processing. The designers around Matthias Ruff have come up with something completely new and very different. With their DSSF-circuit concept Avantgarde Acoustic has found a clever solution to the above problem. DSSF stands for “DUAL STAGE SINGLE Feedback.” Put simply “Forwards fast + backwards fast and little” the DSSF-circuit concept is clearly described. The MODEL5 is a PUSH-PULL transistor amplifier, which operates with only two amplification
www.avantgarde-acoustic.de
Page
7
MODEL 5 stages (see graphic). For each channel you will surprisingly only find two transistors in the signal path. It is impossible to design a PUSH-PULL amplifier any simpler! Short signal paths with fast forward signal processing is guaranteed. One BI-POLAR transistor in CLASS A mode is used for the first stage. Here the input signal is pre-amplified to the optimal operating point of the power transistor. This power output stage is equipped with a modern MOS-FET transistor which amplifies the signal up to 1.1watts at 20 ohm in CLASS A mode and 38 watts at 4 ohm in CLASS AB mode. An additional small regulator transistor – which is not within the signal path! – controls and stabilizes the BIAS settings. It is important to mention that the manufacturer is only using one power transistor per PUSH-PULL loop in the MODEL5. Transistors switched in parallel always have (even when applying the strictest selection criteria) small variations between each other. These add and overlay with the audio signal and inevitably conceal detail of the music signal. All information resolved as a result of the circuitry gets irretrievably lost. Matthias Ruff has found a simple and effective solution to this problem: “What is the best selection? If I simply do not connect any power transistors in parallel“. DUAL STAGE FORWARD AMPLIFICATION The advantages of this DSSFconcept are obvious. The signal only has to pass through two
MODEL 5
SINGLE POWER TRANSISTOR
DUAL AMPLIFICATION STAGES
AMP
AMP
LOCAL LINEARISATION
SINGLE FEEDBACK LOOP VERY SMALL FEEDBACK
GAIN
REQUIRED AMPLIFICATION LEVEL
INPUT LEVEL
DUAL STAGE SINGLE FEEDBACK CONCEPT amplifier stages and thus is extremely fast. “To achieve a fast forward processing of the signal we had to reduce the circuitry to the absolute minimum. There is no other way. Less is here more! With every amplification stage we managed to eliminate, we reduced the distortions of the transistors and increased the linear bandwidth of the circuitry.” explains Matthias Ruff. The MODEL5 achieves bandwidth of more than 220 kHz. This is practically four octaves above the frequency response of a CD. Even the high resolutions of modern recording technologies like SACD and Super AUDIO DVD are handled with ease.
MODEL 5
DUAL AMPLIFICATION STAGES
The MODEL5 is so fast that even highest frequencies above the audio spectrum are amplified linearly. “The faster the forward signal is processed, the higher the frequencies of the feedback distortions occur. With the MODEL5 these problems are practically immeasurable and far beyond the audio range.” describes Matthias Ruff. LOCAL LINEARIZATION Another disadvantage of an OVERALL LOOP FEEDBACK is that it is not the cause of a problem but only the result of a problem when corrected. A distortion generated in the second stage of the amplifier is not being eliminated at the point of origin, but only at the end as the sum of all stages.
MODEL 5
SINGLE POWER TRANSISTOR
AMP
GRAPHIC MODEL5
SINGLE POWER TRANSISTOR
AMP
A P AM
DUAL AMPLIFICAT A ION STA AT T GES TA
A P AM
LOCAL LINEARISAT A ION AT
LOCAL LINEARISATION
SINGLE FEEDBACK LOOP
SINGLE FEEDBACK LOOP
GRAPHIC DUAL STAGE AMPLIFICATION
GRAPHIC LINEARISATION
www.avantgarde-acoustic.de
Page
8
MODEL 5 Not the actual reason but only the symptoms are being fixed. Matthias Ruff gives us a simple example which explains this correlation more easily: “Just imagine you put on some shoes which are too small. After a while you get blisters on your feet. A lotion and band-aid will now alleviate the symptoms but not the cause! If you have a better and faster feedback from your feet, you would have immediately put on some bigger shoes. The problem would have been solved and the blisters would not have developed.” This example makes the biggest disadvantage of a high OVERALL LOOP FEEDBACK in multi stage amplifier designs more obvious: a mistake occurs, after some time it develops into a problem and only than is cured. “The most important thing is to detect the defect immediately at its point of origin. If you than know what’s going wrong, you have to treat the cause precisely and the treatment must solve the problem quickly”. According to Matthias Ruff the key to success is a local linearization concept. For this reason both amplification stages of the MODEL5 are linearized separately. The BI-POLAR driver stage as well as the MOS-FET power transistors have their own linearization circuitry. Each deviation is detected at the point of origin and immediately linearized, independent of the adjacent stage. “We are working with automatically self-smoothing sub-systems
which autonomously do their work and efficiently reduce distortions.” SINGLE STAGE FEEDBACK Nevertheless Avantgarde Acoustic did not want to completely abandon the effective OVERALL LOOP FEEDBACK. Matthias Ruff has a clear point of view in this matter: “People normally only see black or white. Mostly the feedback applied is completely ‘over the top’ or left out totally as in ZERO FEEDBACK designs. Both solutions have many disadvantages. For me the happy medium is the best solution.” The percentage of distortions generated by the MODEL5 itself are inherently small in comparison to normal amplifiers, as it only has two transistors in the signal path, which are even linearized independently by special circuits. For this reason the OVERALL LOOP FEEDBACK can be applied very carefully. According to the manufacturer only the large distortions of the circuitry are equalized. “I purposely do without strong feedback only to get good specifications. If you take into consideration that normal speakers produce higher distortions (by approximately 10%) than amplifiers, you can see that amplifier distortions are highly overrated.” MODEL 5
SINGLE POWER TRANSISTOR
A P AM
DUAL AMPLIFICAT A ION STA AT T GES TA
A P AM
LOCAL LINEARISAT A ION AT SINGLE FEEDBACK LOOP
GRAPHIC SINGLE STAGE FEEDBACK
The designer emphasizes that he has chosen maximum resolution in practical operations instead of optimizing for negligible technical specifications. The main objective is to make the amplifier as fast as possible so that even the finest details of music are reproduced accurately. But how does the MODEL5 with its relatively low feedback behave on complex loads? “The more amplification stages one is using, the slower the circuit is and the more negative the EMF forces appear due to the time delay occurring when the feedback signal has to pass through all amplification stages. A really fast amplifier does not need a high damping factor to control complex loads.” Fast forward amplification is a mandatory requirement for effective control of the EMF forces according to the Avantgarde concept. By removing everything that is not really essential the MODEL5 operates with only two amplification stages. The OVERALL LOOP FEEDBACK can thus be connected from the DRAIN of the power transistor directly to the EMITTER of the driver transistor. There are two separate feedback loops for the positive and negative PUSH-PULL side. Distortionfree summation of both feedback loops is ensured as the driver stage operates in pure CLASS A mode. Whether the distortions are generated by the amplifier circuit itself or induced into the outputs of the amplifier by the EMF forces, the feedback signal only has to go back through one
www.avantgarde-acoustic.de
Page
9
MODEL 5 single stage. The feedback signal is thus immediately present at the input of the driver transistor and passes ultra fast through only two stages to the output. Fast error detection, feedback generation and error elimination at the amplifier outputs are guaranteed with this Single Stage FEEDBACK circuit. “As I am forward fast, I am automatically backwards fast and have to run the feedback through only one single stage?” raves the
designer. Due to the speed of the SINGLE STAGE FEEDBACK combined with the speed of the DUAL STAGE FORWARD amplification, the EMF induced distortions and phase shifts only occur in a frequency band far beyond the audible spectrum. “We did not need to dampen the EMF forces any more with a brutal damping factor, but made the amplifier practically immune to critical loads. The amplified signal is faster than the induced er-
ror and the MODEL5 is resistant against very complex loads and signals.” LISTENING, LISTENING, LISTENING... During the design phase of the MODEL5 these experiences have been exclusively verified in extensive listening tests. As a monitor speaker Avantgarde Acoustic has used their top of the range model: the TRIOΩ OMEGA.
www.avantgarde-acoustic.de
Page
10
MODEL 5 “A horn is the highest resolving and most precise physical principle of all speakers. It will disclose detail, which remain hidden with normal box speakers. For this reason it was clear that we use our best horn system – the TRIOΩ OMEGA – during the design of our MODEL5 amplifier. With the TRIOΩ you can hear immediately even smallest modifications in the circuit layout.” As the TRIOΩ OMEGA is very easy to drive due to its high impedance, Avantgarde Acoustic developed a special test set-up to evaluate complex loads during operation. During the listening tests, several very low impedance speakers placed in an adjacent building were remotely hooked up in parallel. “With this test set up we could simulate very complex loads under normal listening conditions and evaluate the results while listening. The smallest impact on the audible results when switching complex loads on and off was for me one of the most important criteria’s when designing the MODEL5. Actually it is a very simple amplifier, but which achieves optimal results under listening conditions.”
The MODEL5 is not only an ideal amplifier when connected to high impedance horns, but even excels with critical speaker systems. Although it’s damping factor is allegedly not very high, the DSSF concept ensures optimum control and surprisingly neutrality even at extremely low impedances. POWER SUPPLY WITH 7 VOLTAGES The power supply of the MODEL5 utilized a specially manufactured toroidal transformer with a total of 7 secondary windings! This expensive power supply configuration is a surprise if you consider that normal amplifiers can operate with only one voltage. But Matthias Ruff has his own philosophy in this respect: “In the MODEL5 we work with a minimized circuit design but ensure the extensive power supply is absolutely stable in all operational modes.” The special transformer provides (with its shielded secondary windings) a total of 7 different voltages for the independent electrical supply of the different circuit modules, power transistors, displays, relays etc.
Interferences are minimized, as the supply of power to the different components is completely independent from each other. The toroidal transformer has a static and magnetic shielding to avoid electromagnetic radiation into the other components. The power supply of the various circuit modules is buffered by capacitors. For the power transistors 40,000µF of capacitance ensure ample reserves for the relatively small output of this amplifier. MECHANICAL DESIGN The aluminium body has a thickness of 2 mm. The front panel is made of rigid 8 mm milled aluminium. A clever mechanical concept with two nested half shells reduce the surface areas and allow for a resonant-free construction of the body. Additionally, 10 mm aluminium bars in the inside further strengthen the mechanical construction. These as well serve for the mounting of the power transistors and ensure efficient cooling in CLASS-A mode. Punched cooling slots on the upper side of the body ensure a proper cooling air flow of the convection heat. The surface
www.avantgarde-acoustic.de
Page
11
MODEL 5 of the body is powder coated in elegant grey tones. This gives the unit a neutral and robust appearance, purposely simple, timeless and persistent. The oval front display is a reminiscence on the “good old times”. The display quickly reveals the operating mode of the unit at first glance. Channel and volume settings are indicated by stainless steel pointers. All essential functions (volume and channel selection) can be easily accessed with only two big knobs. OTHER FEATURES The MODEL5 integrated amplifier has five RCA INPUTS. As an option INPUT 5 can be reconfigured internally with a jumper into AV-mode. In AV-mode the volume control of the MODEL5 is bridged for the INPUT 5. If you want to integrate your high-end stereo within your home theatre system, you simply have to switch the input selector to INPUT 5. The volume of the left and right front channels is then centrally controlled by the AV processor. The MODEL5 has one RCA RECORD-OUT, one PRE-OUT with XLR connectors for use with active speakers (ex. SOLO) and a SPEAKER-OUT fitted with WBT connectors is used for the connection to the main passive speaker systems. The main power switch is located at the
backside of the unit. Here the MODEL5 can be turned completely off and detached from the mains. In the STANDBY-position of the input selector, a red LED in the display indicates that the amplifier is ready for operation. The display is fully illuminated in white as soon as an INPUT (1 to 5) is selected. If the MUTEbutton of the remote control is pressed one half of the illumination of the VOLUME display is switched off. The brightness of the various displays can be adjusted by the means of three dimmers controls on the downside of the unit. These are accessible from the outside. A specially assigned dimmer to control the brightness of the AV-channel can be set separately. Thus it is possible to automatically dim or switch off the illumination of the MODEL5 in home theatre systems with projection as soon as the AVchannel is selected. A high precision stepper motor controls the volume in small incremental steps. This elaborate solution allows for fine adjustments even at low volume settings. The potentiometer on the audio circuit board in the rear part of the unit is connected to the motor and volume knob through a
long shaft. This way no electrical influence of the motor on the audio section can occur. The remote control, which is included with the MODEL5, is reduced to the necessary functions and allows the setting of the VOLUME and MUTE function. Two infrared diodes will ensure proper operation even at longer distances. The remote control is powered by two 1.5 Volt AAA batteries.
www.avantgarde-acoustic.de
Page
12
MODEL 5 INPUT 5 x Audio, (asymmetrical) Input impedance
5 x RCA stereo pair 10k Ohm
optional (internal jumper) 4 x Audio, (asymmetrical) + 1 x Audio AV-direct, (asymmetrical) Input impedance
4 x RCA stereo pair 1 x RCA stereo pair 10k Ohm
bridged volume control
OUTPUT 1 x Audio Record-Out, (asymmetrical) 1 x Audio Line-Out, (asymmetrical) Output impedance
1 x RCA stereo pair 1 x 3-pol XLR stereo pair 200 Ohm
1 x Speaker output Output impedance SPECIFICATIONS Power output in CLASS A
1 x WBT stereo pair 0,4 Ohm
at 20 Ohm at 8 Ohm
2 x 1.1 watts 2 x 0.4 watts
Power output in CLASS AB
at 4 Ohm at 8 Ohm
2 x 38 watts 2 x 27 watts
Frequency response
-3 dB, 3 watts at 8 Ohm -3 dB, 10 watts at 8 Ohm
Damping factor (at 8 Ohm, dynamic measurement)
20 Hz 200 Hz 2,000 Hz 20,000 Hz
10 – 220,000 Hz 10 – 35,000 Hz 44 21 19 5
Signal/noise ratio
86 dB
Distortions (0.5 watts, 8 Ohm)
100 Hz 1,000 Hz 10,000 Hz
0.03 % 0.03 % 0.07 %
Distortions (38 watts, 4 Ohm)
100 Hz 1,000 Hz 10,000 Hz
0.25 % 0.30 % 2.00 %
* all technical specifications are subject to change without notice
www.avantgarde-acoustic.de
Page
13
MODEL 5 P O W E R S U P P LY Max power consumption Precision power supply
130 Watts toroidal transformer primary secondary secondary secondary
with 7 secondary windings 2 x 115 Volt (50/60 Hz) 4 x 20 Volt (1.2 ampere) 2 x 15 Volt (0.5 ampere) 1 x 12 Volt (1.5 ampere
Static shielding Magnetic shielding Safety standards Mains power connection Fuses (internal)
yes yes UL/CSA + ENEC EN61558 IEC 60320-C14
ON/OFF module circuit board fuse mains fuse
4 x 2.5 ampere (slow) 1 x 2.5 Ampere (slow) 2 x AA mit 1.5 Volt
Battery remote control FEATURES Rigid chassis
heat sink front plate rear plate chassis cover
10 mm / 0.393 in 10 mm / 0.393 in 3 mm / 0.118 in 2 mm / 0.078 in
Analog display Illumination STANDBY Mode Illumination ON Mode (channel 1 – 4) Illumination ON Mode (AV channel) Illumination MUTE Mode
volume + input
dimmer included separate dimmer included 1 side of display turned off
Remote control DIMENSIONS / WEIGHT Dimensions
red LED white LED white LED white LED volume + mute
height width depth
Weight
* all technical specifications are subject to change without notice
72 mm / 2.8 in 340 mm / 13.4 in 379 mm / 14.9 in 7.5 kg / 16.5 lbs
www.avantgarde-acoustic.de
Page
14
SOLO
UNO
DUO
TRIO
Avantgarde Acoustic GmbH Nibelungenstr. 349 D–64686 Lautertal Germany Tel: +49 (0) 6254/306-100 Fax: +49 (0) 6254/306-109 email:
[email protected] www.avantgarde-acoustic.de
Page
15
