Active Bi-Amping FAQ for anyone wondering what the hell it is I'm doing:
“What is Active Bi-Amping?”
Active bi-amping uses one amplifier for low frequencies and another for mid/high frequencies—per audio channel. This is done via the use of an active crossover unit which is inserted between the preamplifier and power amplifiers.
“What are the advantages of active bi-amping?”
1) It provides much greater driver control than a passive crossover/full-range-loaded amplifier configurations.
2) It provides a better load for your amplifiers to drive, and an effective gain in each amplifier’s effective output. It will provide lower amplifier-originated intermodulation distortion (IMD).
3) It provides much greater protection of your tweeter/midrange drivers under clipping/overload conditions.
4) It provides the ability to use less expensive amplifier designs for each driver.
5) It provides for time alignment of drivers within a single speaker (a “must have” capability)
6) It provides for better crossover performance in both amplitude AND phase in the crossover region for smoother crossover performance, including more stable soundstage imaging vs. frequency.
7) It provides stability of crossover performance relative to passive crossover drift during and immediately after under high-load speaker output conditions, i.e., it maintains electrical output linearity under heavy load conditions.
It requires lower-quality wire/connectors than a similarly configured passive crossover/full-range amplifier configuration.
9) It allows on-the-fly changes in crossover frequency, EQ and channel gain settings to support changes in your setup configuration, i.e., facilitating the fine-tuning use of tools like Room EQ Wizard [REW], replacing individual drivers, speaker position changes, and adding channels for playback (2.0, 5.1, 7.1, etc.).
“What are the disadvantages of bi-amping?”
1) It requires two power amplifier channels per speaker (with associated wires/connectors).
2) It requires an active crossover unit.
“What is an ‘active crossover’?”
1) An active crossover provides separation of frequencies of the incoming pre-amplifier output signals, breaking each upstream channel into two downstream channels (a woofer channel and mid-range/tweeter channel).
2) It provides higher-quality equalization (“EQ”) capability for each channel.
3) Digital crossovers typically provide for delay to allow for time alignment of the drivers within a single speaker. (This is a similar function to an AV Processer that time aligns speaker-to-speaker in a 5.1/7.1 array.)
“Do I need to disconnect my speakers’ passive crossovers from my drivers?"
Yes. At least the woofer (or low frequency driver) must be disconnected from the passive crossover to permit bi-amping. If your speakers are 3-way (i.e., woofer, midrange, tweeter in each cabinet), then you may retain the passive crossover between the midrange and the tweeter if using bi-amping (…but for tri-amping, all drivers must be disconnected from the passive crossover networks)
Can I use ‘passive bi-amping’?”
Passive bi-amping does not bring the benefits of active bi-amping, only the disadvantages of extra cables and connectors. Generally, it may not worth the expense of the extra amplifier, depending on your speaker power requirements. In particular, passive bi-amping does not provide for delay adjustment or filter/EQ parameter flexibility.
What active crossover brands/units should I use?
Many manufacturers make active crossovers, including ElectroVoice, Yamaha, Ashley, Behringer, Rane, Pass Labs, Marchand, Bryston, DEQX, etc. Prices go from around $150(US) to many thousands of dollars. Price is generally commensurate with sonic performance…
Have I seen active crossovers used in configurations other than a active crossover box?
Probably--the "powered subwoofer" channel found on most AV Receivers/Processors is a limited example of a for-purpose active crossover channel (i.e., mono bass channel). Usual features include gain control (at the integrated subwoofer/power amplifer unit), user selectable crossover frequencies, and sometimes Geometric GEQ/PEQ (graphical and parametric equalizer) filters built into the AVR/AVP.
Delay adjustment for each speaker channel is usually included in the AVR processor functionality to correct for speaker distance room placement variances. Additionally, an "Audyssey"-like feature on some AVRs/AVPs features a built-in real-time analyzer (RTA) to help the user set up their speakers in a room environment.
Also:
http://sound.westhost.com/biamp-vs-passive.htm
