Alesis ProLinear 820 DSP Active Studio Monitor
The Alesis ProLinear 820 DSP continues the new standard in near-field monitors that was set by the ProLinear 720 DSP. With the same custom DSP technology, the folks at Alesis have designed a speaker with same sound quality and accuracy but with extended bass and greater output. This allows the speaker to be used as a mid-field monitor as well as near-field. As with the 720 DSP, the internal processing allows user flexibility to configure the speaker for almost any application via the front panel control or the included graphical PC application software. Price per speaker.
It Begins with the Drivers
Any great speaker design starts with the best drivers and the Alesis’ custom drivers are exceptional. The woofer has a cast frame with an 8” Kevlar-Carbon cone and oversized magnet assembly. The Kevlar-Carbon cone has outstanding stiffness to weight ratio to minimize distortion, extend bass response and provide excellent transient response. The magnet assembly provides high linearity and good efficiency. In the 820 DSP cabinet, the woofer is flat down to 39hz (-3db, anechoically) with harmonic distortion typically below .4% above 50hz.
The tweeter is a 28mm silk dome that has a very flat frequency response with a low resonance to reduce harshness. The tweeter is ferro-fluid cooled to provide good power handling and well-behaved response. Distortion is typically below 0.3% over its operating range. The tweeters computer designed waveguide was optimized for nearfield placement but provides excellent imaging in most other placements.
Both drivers are shielded and allow the user to place the speakers within a few inches of a CRT
Since the 820 DSP cabinet is larger than the 720 DSP, heavy bracing was included to minimize any cabinet resonances. In addition, a coating of bitumen was applied to the inner walls to further deaden the cabinet. Venting was optimized to eliminate most of the vent noise or “chuffing” that can occur at low bass frequencies.
Why Use DSP?
1. The Crossover
With Alesis’ custom DSP processing, the crossover for the drivers achieves a linearity that is usually unachievable in analog monitors. This allows a smooth transition of the sound between the tweeter and woofer as well as providing proper time domain coherency. In other words, the speaker is as accurate as the drivers. The DSP also allows us to smooth out the frequency response far more effectively than with analog monitors. The response is typically better than +/- 1dB between 100hz and 20Khz.
2. Speaker Emulation and Modeling using the Programmable EQ
There are 4 programmable, user controlled, fully parametric equalizer bands to adjust the speaker to a desired response. The speaker has 16 stored programs (8 PRESETS and 8 pre-defined USER variable settings). Any of these settings can be varied, but only the USER settings can be overwritten.
3. Level Adjustment
One cool feature of the Prolinear DSP is the level adjustment, which allows the user to calibrate the input level to match other speakers. Simply invoke it by pushing a couple of the front panel buttons and the liquid crystal display (LCD) will display the input level into the speaker. To calibrate the speaker, input a constant test signal (e.g. pink noise, white noise) and adjust the rear panel pot to the desired level.
The internal processing of the ProLinear DSP provides external RS-232 serial ports that allow the user to connect the speaker to a PC or other speaker in a daisy chain (with the included serial cables). The functions that can be controlled through the serial port include setting of the 4 parametric bands, level control and selection of the 16 stored programs. Via a single PC, any number of speakers may be controlled. Each speaker has a channel ID number (from 1 to 16). Any speaker with the same ID will be controlled at the same time. This means that you can have 16 speakers addressed individually, or an unlimited