A4.4

In real world audio applications, available power can be limited by long AC power cable runs (extension cords) and affected by the quality of wiring in the wall itself, or by the distance from the breaker or fuse panel to the wall outlet. Available AC power can also be severely limited if multiple amplifiers (or any devices) are forced to run on the same circuit.

Conventional power supply non-power factor corrected amplifiers have to severely limit their output power relative to the available current at the AC source input. In short, less available AC power at the amplifier's input means less audio power at the output. The peak current demands (powering repetitive kick drum hits, playing back long low synth drones) of an audio amplifier exaggerate the problems of line sag in power distribution. This is why it is common to spec amplifiers considerably larger than the ratings on the speakers would suggest.

The power supply characteristics greatly affect the audible differences between amplifiers. Engineers designing the A4.4 knew the importance of the power supply dynamics. These do not show up on conventional bench tests. The burst power measurements indicate a difference, but that specification doesn't tell the whole story. The audio quality of an amplifier appears as differences in apparent power output with real loads, real music and real AC power.

The design goal with the A4.4 was to preserve the dynamics of our successful conventional supply amplifiers while eliminating the undesirable effects of real world AC distribution problems.

Enter the Switching Power Supply

Switching Power Supplies are an alternative technology with greatly reduced weight and improved performance over iron core transformer conventional power supplies. Since they can compensate for AC input voltage sag, they can put out their maximum rated power even if wall voltages are low or fluctuating. As a side benefit, a switch mode power supply is much smaller and lighter than any conventional iron core transformer power supply.

In order to output their maximum power with reduced input voltages, the switch mode power supply must draw more current out of the wall. Where a conventional power supply amplifier would reduce its output power relative to its input current, a switching power supply can and will draw more current, and maintain the audio output at full power.

Add Power Factor Correction

A Power Factor Corrected amplifier can make the most efficient use of its available wall current or ability to create usable output power for a given input current.

When the input voltage sags (Volts), a switch mode power supply must increase the current draw (Amps) to maintain its output power level (Watts). Good power factor correction allows the amplifier to better continue to operate without tripping the AC source circuit breaker, while making maximum watts from the available input voltage.

In short, this means that if you compare the power factor corrected A4.4 with its switch mode power supply against competitive conventional power supply amplifiers, including our own AP4040, the A4.4 will sound louder and consistently deliver more volume in real world audio operations.

The A4.4 Advantage

Combine a switch mode power supply with good power factor correction, and you can make the most efficient use of its available wall current, or ability to create usable output power for a given input current.

If you have an amplifier rated at 1200 watts per channel at a 4-ohm load with conventional supply and no power factor correction, with 120 volts available at the AC source, you can expect to see that 1200 watts per channel. However if the A.C. input line voltage were to sag to 110 volts, that same amplifier's output would drop to 1050 watts per channel into that same 4-ohm load. At 110 volts at the AC source, the AudioPro A4.4 can and would deliver its full 1200 watts per channel.

This becomes even more dramatic when the input line voltage sags as low as 105 volts, which can easily happen at the end of a long AC cable run, or where there are multiple amplifiers on the same AC circuit. - With only 105 volts available at the input, an amplifier with a conventional power supply and no power factor correction will only deliver 950 watts per channel at a 4ohm load, where the A4.4 with a switch mode power supply and power factor correction can and will deliver a full 1200w per channel.

Please note: The terms 'Switching Power Supply' and 'Power Factor Corrected' are not interchangeable. Competitive power amplifiers that advertise the use of Switch Mode Power Supplies are not necessarily also Power Factor Corrected, and will not necessarily perform as well as the A4.4. Yorkville's A4.4 is somewhat unique as it is in fact a 'switch mode power supply' amplifier that is 'power factor corrected'. This is why the A4.4 out performs most of the competition in this class, and in fact does 'sound louder' when compared to a conventional power amplifier.

A-Series amplifiers are not only suitable for use in both heavy duty touring sound reinforcement systems but also when high headroom and low distortion are needed to fully reproduce the dynamic range and clarity of today's digital recordings. They are built to survive grueling road conditions and will drive reactive phase shifted loads with no difficulty - even though they are fully protected from accidental short circuits. Unlike many of our competitors, Yorkville power amplifiers are designed for rock solid performance right down to and below their lowest impedance ratings. This impedance aware strategy deals with the realities of driving typical reactive speaker loads and the associated problems such as thermal shut-down, inductive 'snap-back', and premature current limiting.

All A-Series amplifiers undergo a thorough computer-monitored, temperature-cycled, burn-in period to test for any deviation from design parameters. The designs, while unique, are conservative with regard to the power handling capabilities of the output devices. The computer optimized heat dissipation system ensures that excessive thermal stress will not occur. Cool, clean air is supplied to the amplifier via fan-assisted front-to-rear venting. A user-serviceable filter is incorporated into the front mounted air intake grill, ensuring long-term reliability. Front panel Power, Protect, Activity and Clip LED's are bright and easy to see and all knobs and handles are recessed for safe, easy transportation. All A-Series power amplifiers also feature full DC, load and thermal protection while a user-defeatable limiter maintains full output without audible clipping.

The back panel features Speakon™ and binding post outputs as well as balanced XLR & ¼" TRS inputs. The peak limiter, subsonic filter, mono/stereo/bridge mode and ground lift switches are also mounted on the back panel.

Features

• The same tried, tested, rugged and reliable power module from the AudioPro AP4040, our best selling power amplifier to date
• Sounds louder than a conventional power amplifier in virtually all real-world applications
• Switching Power Supply - maintains its maximum rated output power even when input line voltages sag as low as 85 volts - long after a conventional amp would shut down
• Power Factor Corrected - maximizes use of the available input current with less likelihood of tripping the wall breaker
• About 18lbs lighter than the AP4040. For a touring rig, four A4.4's in a rack would be around 98lbs, (plus the rack) versus 180lbs for the same number of AP4040's
• Speakon™ and binding post outputs
• Balanced XLR & ¼" TRS inputs
• Long-life, faceplate-mounted, user serviceable, air intake filters
• Sturdy all-steel construction
• Baked-on, black finish
• Reinforced mounting ears
• Rear panel peak limiter
• Rear panel subsonic filter
• Mono/stereo/bridge mode switch
• Ground lift switch
• Covered by Yorkville's two-year unlimited warranty*

* Warranty valid in the United Stated and Canada only

Specifications

Specifications subject to change without notice