1961 Subwoofer 1S

Highlights

• High resolution 1.8” LCD display
• Smart amplifier technology
• Full 550W RMS down to 10Hz
• Extensive multi sensors to protect and preserve signal quality
• Safety controls

Intelligent Technology

´Intelligent´ is rarely used in the audio industry, especially for speakers and subwoofers. The new Avalanche 550 IQ subwoofer amplifier from Arendal Sound is one exception, measured in performance and technology. State of the art amplifier designed and developed from scratch to give performance and features you could not get before.

The Avalanche 550 IQ boast killer performance and has features under the hood yet unseen in the industry. Multiple sensors in the digital and analog domain, from inputs to outputs to preserve dynamics and clean bass. It has a powerful microcontroller (MCU) which is the brain that controls and reads all data that passes the signal flow. To make sure the signal is as untouched as virtually possible, from its original source to the output from the subwoofer.

Research and development over two years, fully customized by Arendal Sound. The Avalanche 550 IQ is a smart and intelligent beast of an amplifier.

Avalanche 550 IQ Features

Highlights

• Hi resolution 1,8” LCD colour display
• Dual Source assignable RCA inputs
• Selectable 12V trigger and auto-on functions for each input
• RCA passthrough outputs
• User adjustable on-time and auto-on wake-up settings
• Variable phase & signal invert
• EQ modes & 3 band Parametric EQ
• Low pass filter & slopes
• Subsonic filter & slopes

Subwoofer amplifiers will never be the same again with the new Avalanche IQ technology.

High resolution display user interface

With few features added to a subwoofer amplifier, it needs few buttons and switches. However, with the Avalanche 550 IQ amplifier, it offers features outside the scale in this price range where physical buttons would not fit the amplifier plate even if we wanted to. The 1.8” High Resolution colour display will give you a clear overview of all settings for your subwoofer. With the multi control knob and buttons with great tactile feedbacks, you will make any setup and adjustment a breeze.

Avalanche 550 IQ offers a ton of features that are unheard of in this price range.

RCA I/O

Avalanche 550 IQ has some aces on its hands. First, it has RCA in- and outputs, but that’s just where it starts.

3-12V trigger

If you have hidden your subwoofer behind a sofa or inside a baffle wall and still want to dictate it being on or off (not using the auto on function) we have a 3-12V trigger connection with 3.5mm jack. The Avalanche 550 IQ listen to your source control and powers up when your system does, then powers down when you turn your system off.

Auto on/off

Auto on is a feature that wakes up the subwoofer when you start playing material from the connected source. Most subwoofers on the market have different wake up sensitivity which can bring problems for some systems since you cannot change the sensitivity on its inputs.

We did not give you just one option with Avalanche 550 IQ. With the new auto on function you have multi-level to choose from so you can get your subwoofer to wake up at the right time you play sound. Choose between low, medium and high wake up sensitivity and you are set for a seamless use of your subwoofer.

Times where you need to crank up the master volume to get the subwoofer turning on is gone with the new auto on feature.

On time

To save energy, it’s important that your equipment shuts down when it’s not in use. Avalanche 550 IQ lets you decide when it should sleep after use by 5-60 minutes with 5-minute increments.

Dual Source Input

Are you combining stereo and multi-channel equipment in one system and you want to use one subwoofer system for both? Yes, we got you covered! This is a unique feature only provided from Arendal Sound through the intelligent amplifier, Avalanche 550 IQ. With your new subwoofer you can control which input you want to be used from your stereo and AVR so it locks to that single input only. You can lock the signal to input 1 or 2, or you can also select 1 and 2 at the same time. This means you can control the inputs based on what you are playing, and Avalanche 550 IQ manage signal flow in both your systems.

Old school fiddling with adapters and connecting back and forth with multiple subwoofer adjustment going from stereo to AV, and the other way, is gone. Thanks to Avalanche 550 IQ.

Variable phase & Signal invert

Avalanche 550 IQ is equipped with both adjustable phase and signal invert. Signal invert inverts the signal, which means the same as 180 degrees phase, however this is “true” 180 degrees at all frequencies. Where variable phase will slightly move depending on frequency, as on all variable phase shifts. These two settings are very handy to get the perfect alignment in a stereo system where there is no processor that can time delay the signal.

EQ Modes & Parametric Equalizer

We offer two EQ modes to choose from, where you get a flat frequency response in half space down to under 20Hz in EQ1 mode, and EQ2 mode will start tapering off at a steady pace around 40Hz. The latter will typically work very well for smaller rooms or in music playback where slightly less deep bass is preferred.

Avalanche 550 IQ also has a built in 3-band PEQ that can be tailored to suit your room. It is extremely accurate to enable a perfect integration in your room. Where the frequency is set at 1Hz-increments and the Q is adjustable all the way from 0.3 up to 10, so you can target sharp irregularities in your room response.

Levels & Input gain

The Avalanche 550 IQ amplifier is equipped with an adjustable input gain to match your source output level, as well as an adjustable master level for perfect integration in your setup. You also have the option of setting the level to reference position, which is recommended for most users with an AVR. For ease of use we have also incorporated a feature that allows you to select reference level for multiple subwoofers used together in the same setup.

Low Pass Filter and Slope

Low Pass Filter (LPF) is selective on or off and can be adjusted to 30-160Hz with 1Hz increments. Also, for the feinschmecker, the LPF slope can be adjusted with 6/12/18/24dB filter curves to tune the subwoofer perfectly for your system. You are of course able to adjust phase by 10-degree increments and full signal invert (on/off).

Subsonic Filter and Slope

Subsonic filter is user selectable and adjustable from 12 to 31 Hz, or you can completely turn it off. The slope is also adjustable from 6 to 12 dB pr. octave. This feature can come in handy to get the deep bass level properly adjusted for your room or preferences. The amplifier has a built-in subsonic filter that is enabled at 10 Hz, to protect the amplifiers power supply.

Avalanche 550 IQ Technology

Power amplifier

Each bridged power amplifier module has a 32-bit microcontroller (MCU) for control and monitoring purposes. This MCU communicates with the MCU in the Digital Front End PCB.

The power amplifier module MCU utilizes 5 channels of A/D (analog to digital) conversion to monitor the following parameters in real time at a rate of 1000 samples/second:

• The output voltage of amplifier A and B (the two halves of the bridged amplifier)
• The power supply rails (positive and negative voltages)
• The module temperature sensor

By monitoring these parameters and the over-current detector, fault conditions can be instantly recognized and will result in the amplifiers being shut down immediately.

Safety and reliability

Certain strategies are employed to increase the margin of safety and reliability: For example, the power supply rail voltages are measured before the power amplifiers are enabled. If either rail voltage is outside of the normal limits, the amplifiers will not be enabled, and the power supply will be shut down. Since this is a bridged amplifier, the output voltages of both amplifiers should always be equal and opposite (A+B=0).

If there is a fault condition in either amplifier, the MCU can recognize it within 1 millisecond (1/1000 of a second, ms) and shut down the amplifiers. A typical single-ended power amplifier with an analog offset detection circuit must have a long time constant (> 100ms) to distinguish between DC and a low frequency signal.

Startup logics

All of the parameter margins (limits) are part of the Digital Front End firmware. They are downloaded to the amplifier module(s) at power on. In the case of any fault condition, the power amplifier MCU will inform the Digital Front End MCU and include the specific fault information.

The strategy for each type of fault is decided by the Digital Front End MCU firmware. For example, an amplifier restart may be tried in case of an over-current condition with a limit of X number of restarts.

Troubleshooting

To make troubleshooting easier, the Digital Front End MCU will display the error information on the LCD display in case of a fault condition.

The power amplifier MCU also keeps statistical information that could be used in a variety of ways: Number of clipping events, maximum and minimum values for all monitored parameters (such as max/min rail voltages). This will be crucial for the Arendal Sound engineers to understand if there are any problems or strange behaviour of the amplifier.

Self-testing

The Digital Front End can run a complete self-test of the entire system. This includes generating a test tone and measuring the amplifier output voltages and all other parameters. Any failure will be displayed on the LCD screen.

ROHS, FCC and CE certified.

It was only natural to make the 1961 series with a smaller driver than that of its bigger brother the 1723 series with their 13.8” drivers, considering their price difference. We still wanted to have a slight edge over conventional 12” drivers in terms of surface area so we designed and created a custom 12.2” driver which requires less excursion and power to achieve the same SPL levels as a standard 12”. Every part of this driver has been thoroughly engineered, Klippel and FEA analysed and customized to deliver high output, low distortion, accurate bass. Designed to get the typical explosive, hard hitting dynamics, precision control and bass definition required to resolve the finest details of music that Arendal Sound is known for from the 1723 Series.

Modelling

While many brands may advertise FEA design and modelling, usually this only refers to the basic magnetic circuit. Arendal Sound has taken the science of transducer modelling to another level. The motor topology is firstly designed to meet flux density and excursion requirements. Then the materials and geometry are fine tuned to minimize flux modulation and stabilize the inductance vs both position and current. Lastly, the voice coil stroke or BL(x) shape is optimized for zero-point centring and symmetry which are the final points for maximizing motor control over excursion and minimizing distortions.

We use non-linear FEA modelling to analyse the compliance of both the spider and surround to achieve excursion requirements and optimize Cms(x) to compliment the motor. This translates to increased excursion and lower Distortions which equals maximum sound quality.

Lastly, we utilize Klippel Laser based diagnostics. It’s a tool often misunderstood, but when used properly in conjunction with component design, a woofers design can be dialled in. Klippel testing basically serves to confirm the initial FEA modelling and accuracy of part tooling and offers the diagnostic abilities to allow our engineers to refine the initial designs until final goals for excursion, linearity, stability and distortion are met.

Materials selection and design

Low carbon steel specifically chosen for its ability to carry more flux is used in the magnetic circuit. The T-pole piece is CNC milled to final dimensions to ensure tight tolerance, proper fit and prevent flux robbing losses often found in typical motor assemblies.

Aluminum 6063 shorting rings are strategically placed in the motor circuit to prevent flux modulation, increase stability, lower inductance and improve heat sinking from the voice coil. These are of course CNC machined to tight tolerances.

Ultra-High temp Aluminium voice coil wire is chosen for its weight to conduction properties and lower sensitivity to temperature change, compared to copper. This results in higher efficiency and lower thermal compression. This combined with the highest thermal rated insulation and adhesive layers available, goes to ensuring high durability under demanding conditions.

The choice of spider material is a key component to sound quality, which is often overlooked. We use a blended Nomex and Poly-cotton multi-layer spider. This combination of materials allows for excellent excursion control, low mass and high durability.

We chose to use Isoprene Rubber (IR) Surround on our drivers, which has the advantage of low mass density. This allows for higher excursion designs without sacrificing woofer efficiency.

Our cone consists of long fibre pulp that has very good stiffness to weight ratio, plus it delivers a properly self-damped driver. The result is a cone that achieves optimal pistonic motion at all frequencies it is asked to produce and beyond.

The entire moving assembly is designed to have the lowest possible weight while still achieving the desired frequency roll off. A lower total moving mass combined with low inductance typically lends itself to having better transient response, dynamics, “slam” and “impact”. Furthermore, we have designed the surround to have a non-linear compliance in order to reproduce as tight as possible bass without affecting the distortion at the lowest frequencies.

Air flow venting

Air flow venting underneath the dust cap (vents in cone body) and spider (vents in frame) are added for two very important reasons. Air heated by the voice coil is forced away with each stroke of the cone diaphragm. This continuous exchange of air mitigates thermal compression and increases the woofer’s overall power handling capability. Second, the airflow relieves asymmetric compliance (suspension stiffness) and noise (distortion) due to non-linear compression and rarefaction of air typically trapped under the dust cap and spider. Typical, vented pole designs will be limited in effectiveness due to the lack of airflow volume – At the highest power and excursions, where free, smooth airflow is needed most, the pole vent alone is not sufficient.

For our 1961 series speakers and subwoofers we did not cheap out on looks. We felt using typical pin inserts in the cabinet and grills, as most manufacturers will in the price range, just did not feel right. We custom designed and tooled our own grills in ABS plastic material including neodymium magnets in both the cabinets and grills, with a protective rubber surface to avoid scratches.

The grills are perforated and free flowing, wrapped with a thin fabric cloth, ensuring they do not affect sound quality. And get that right Arendal Sound look to them.

There is something enjoyable about the nice “thud” when you let the grills seat, be it on one of the speakers or a subwoofer. You can rest assured that the sub-surface neodymium magnet will hold the grills tight in place to avoid any rattling sound during playback.