BASS

Subwoofer SUB225 CTRL PRO

We are pleased to announce that an entirely new subwoofer, SUB225 CTRL PRO, has been developed and is now standard for models DUO and TRIO (optional for UNO). This new and exciting development consists of an actively "real-time" controlled subwoofer equipped with two powerful 10 inch drivers.

With this new SUB225 CTRL PRO, it was our goal to design a subwoofer that reached the absolute limits of today's technology. This unique combination -- compact rigid enclosure, newly available driver systems, active frequency crossover, custom power amplifier, and active real-time control circuitry has resulted in a new generation of subwoofers.

Having met virtually all of our design goals, the all new SUB225 CTRL PRO marks yet another landmark achievement for Avantgarde's Spherical Horn-speaker Systems.

New Avantgarde 10T300 Bass Driver

Two powerful 10T300 drivers drive the subwoofer module SUB225 CTRL PRO. Developed exclusively for Avantgarde, these 10 inches drivers are not simple "off-the-shelf" mass produced woofers.

In fact, as you'll hear, these drivers are finally worthy of comparison to our renowned spherical horn speakers.

The unique design parameters of the 10T300 speak for themselves. The material of the cone consists of a specially developed paper with a structured back-side. This gives the cone its incredible stiffness and acoustical neutrality, thus eliminating harmonic distortions and interference in the upper frequency range. Just gently rub with your finger from the outside to the center of the cone... you'll immediately feel and hear its quality.

In spite of the extreme rigidity and stability of the cone and its material structure, utilizing this design allowed us to further minimize the moving mass. The result -- a musically significant step forward in hearing the subtleties of pitch and dynamics, with a new level of definition that allows the listener to hear (and feel) deeper into the performance.

The enormous 3 inch voice coil is absolutely oversized for a typical 10 inch driver. When you consider the massive 7.6 inch high-energy magnet, with over 15 lbs. of clean magnet power, the message is clear "Here I am the BOSS!"

The incredible BL-force factor of the 10T300 with more than 19 Newton per ampere is absolutely unique for a long excursion driver of this kind. This powerful motor structure forces the cone to instantly follow the input signal, doing it with power and authority. The results are impressive -- fast and dynamic like our horn speakers, with low frequency extension and precision par excellence.

The membrane of the 10T300 has an optimized suspension which allows for an extremely long excursion (0.71 inch) of the 3 inch voice coil in the symmetrical magnetic field. Even at large excursions, the driver will always be fully within the gap of the high-energy magnet and the pole structure. The advantage of this design is its exceptional lack of dynamic compression even at deep frequencies and at very high levels.

The 10 inch driver is rated at 250 Watts (RMS) and 500 Watts (peak). This power rating is combined with a very high sensitivity of 95.0 dB. Both 8-ohm drivers are run in parallel. Therefore, the two 10T300s yield an impressive efficiency of over 100 dB per enclosure, matching well with our spherical horns for dynamics and clarity.

All relevant technical specs, even driver impedances, are held to the tightest tolerance limits. This is a "mission-critical" standard when employing custom-tuned active amplification (see "The Real-Time Feedback" below).

Bass Enclosure

The enclosure of the SUB225 CTRL PRO has exactly the same dimensions as our standard SUB217 series. Thus the new subwoofer generation -- with its size of 11.8 inch x 21.7 inch x 21.7inch, WxHxD -- is fully compatible with our systems DUO and TRIO. Existing systems can easily be updated. Optionally, UNO may also be fitted with SUB 225 CTRL PRO.

The enclosure is constructed in axial symmetry. Designed with a centrally located reinforcing stabilizer, the box construction is very rigid, avoiding resonances. The enclosure is solidly built with 1.2 inch MDF. The total weight of the SUB225 CTRL PRO is 100 lbs.

Finished in elegant anthracite, the subwoofer surface is coated in high quality NEXTEL.

Active Control Power Amplifier PA101

The active module PA101 is integrated on the rear panel of the subwoofer enclosure. The PA101 consists of an active frequency crossover, a powerful 200-Watt amplifier, and a velocity control system to continuously monitor and control driver movement.

Active Frequency Crossover

The active module PA101 is driven via high power input terminals for direct connection to integrated amps, power amplifiers or receivers. The signal take-off is not only at high impedance, but is also balanced and transformer-coupled. This floats the subwoofer ground, avoiding hum loops and eases connection to balanced and bridged amplifier designs.

An additional musical benefit arises from an enhanced continuity of sound between the subwoofer and mid-range horn, because the tonal and dynamic characteristics of the amplifier or receiver are kept intact. When the listener ceases to be aware of the disparate character of sounds, the suspension of disbelief is facilitated. And musical enjoyment begins.

Additionally, due to the benign (high impedance) load characteristics of the active module (with its powered subwoofers), music lovers can enjoy using small high quality amplifiers, because -- perhaps for the first time -- such amplifiers are enabled to deliver extraordinary bass extension, definition and dynamics.

The active crossover allows the adjustment of a number of parameters thus ensuring a very easy and fast installation of the system even in acoustically critical situations. The subwoofer level and the crossover frequency can be adjusted by the means of a potentiometer. A polarity invert switch copes with circumstances where a local standing wave exists at the crossover frequency.

200 Watt Power Amplifier

The power amp of the PA101 module has a substantial 270VA toroidal transformer. The 40,000 uF of the power capacitors provide the necessary high-energy reserves for critical passages. The amp is optimized for bass reproduction and has a high damping factor for precise control of the drivers.

To avoid noise when switching the amp on, the PA101 is equipped with a Soft-Start automatic. This circuit gently powers the amp into operation, thereby avoiding the use of conventional relays with their noise and reliability issues.

Velocity Controlled Driver Feedback

The SUB225 CTRL PRO is an actively controlled subwoofer. In contrast to conventional amplifiers -- which only compare the output signal with the input signal -- our active module PA101 actually compares the speed of the driver membrane with the input signal.

Thus, the feedback loop not only eliminates deviations of the amp itself, but also the deviations of the drivers. As soon as the circuitry detects a deviation, it immediately adjusts the power accordingly (e.g. the power is increased or decreased). As result the SUB225 CTRL PRO achieves an astonishingly flat frequency response of 18-250 Hz with only 0.8 dB deviation!

"Real-Time" Feedback

The unique feature of the SUB225 CTRL PRO is the speed at which this active control system works in real life, with real music. It's so fast that it works silently in the background without the listener ever noticing its presence. This was achieved with a unique combination of innovations:

1. The state-of-the-art 10T300 Drivers. Two 10 inch drivers with oversized 3 inch voice coils and 30 lbs. of pure magnet power push the extremely stiff membranes forward with an incredible force of 38 Newton per ampere. Every input signal causes an explosion-like thrust of the membranes, like a piston of an engine. The driver reacts extremely fast and with sovereign authority. With a combined driver efficiency of over 100 dB per enclosure, you get power and delicacy in one package! Subtle changes in the signal are precisely converted into pure clean sound. The active control is thus only used to linearize the frequency response of the small enclosure and not to compensate for deficiencies of the drivers. The entire power is fully and instantaneously available for dynamic headroom and is not wasted to fix problems in other areas. The result is unparalleled effortlessness, with the kind of bass usually heard only at live events.
2. The "lean design" of the circuit contributes to the speed of the active feedback system. The SUB225 CTRL PRO utilizes a sophisticated control circuit that completely eliminates the need of control sensors, electronic analyzers and computer chips. Simply by subtraction of the output values of voltage and current, compensated with the precisely known speaker parameters, our extremely fast analog circuits measure the exact speed of the membrane. The total absence of delays caused by sensors, cable lengths and analyzers allows us to operate the PA101 feedback in Real-Time-Mode. Working incredibly fast, the active control does its job effortlessly, blending the quick responding SUB225 CTRL PRO almost seamlessly with the horns. The listener ceases to be aware of bass as a separate "sound" coming from a speaker, and soon the music is affecting his emotions...
3. Theory is one thing, reality another! Ideally in overall feedback systems, the movement of the membrane will exactly follow the input signal. But this is only the case when the feedback circuitry can precisely compensate for the actual behavior of the driver. However, even small deviations in the production series of the drivers would automatically cause faulty adjustments of the feedback system. For this reason we measure the impedance curve of every 10T300 driver in our lab. Then the 10T300 drivers are selected in pairs within 0.1-Ohm tolerance! All relevant data of both units are precisely known and kept in our driver database by batch and serial number.
4. Finally, as the last step, we exactly compensate for the impedance and inductivity of the voice coil through an adjustment of the reference components in the feedback loop of the circuitry. Thus the amplifier is exactly matched and tuned to the drivers built into the cabinet of each SUB225 CTRL PRO!

It's not enough to achieve occasional greatness -- it must be consistently repeatable for each Avantgarde speaker system we ship. Plus, in the unlikely event you should need to replace a driver or amplifier, you can be sure of continuing quality control and performance, at the level you expect and deserve.

The "Real World"

Amplifier designers normally always have problems matching their amp designs to a certain species of speakers. But they never really know what kind of speaker the user will finally connect to their amp design. Thus every amplifier is more or less some sort of compromise and it can never be optimized to its limits.

There are no such compromises with the active module PA101! Not only the type of speaker, but also the exact values of each built-in driver are precisely known. Thus each PA101 can be precisely tuned and matched to its load in "real life." The power amp always knows what it is driving and how it has to do its job. With the SUB225 CTRL PRO, nothing is left to chance. The result is a new reference in bass quality and -- most importantly -- bass musicality.