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“What is Active Bi-Amping/Tri-Amping?”

 

Active bi-amping uses one amplifier for low frequencies and another for mid-to-high frequencies—per audio channel. Tri-amping adds one more amplifier for a 3-way system tweeter. 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/tri-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.
  8. 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 active bi-amping/tri-amping?”

  1. It requires two/three 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 (bi-amping) or three (tri-amping) 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 Processor 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 is not worth the expense of the extra amplifier. 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, dBX, Yamaha, Ashley, Behringer, Rane, Xilica, Lake, Marchand, Bryston, DEQX, etc. Prices go from $230(US) to many thousands of dollars. There are also lower-cost alternatives, such as miniDSP.  Price is generally commensurate with sonic performance.

 

Have I seen active crossovers used in configurations other than an 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 amplifier unit), user selectable crossover frequencies, and sometimes 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.

 

(16 Nov. 2010 edit)

Can I use a 2-in, 4-out processor (like the EV Dx38) to Tri-amp my three-way speakers?

 

Yes: if you disconnect two of the three speaker drivers from their passive crossovers, then connect the tweeter and (usually) midrange driver to the 2-in, 4-out processor, leaving the last (usually woofer) channel connected to one amplifier, and the other two outputs from the active crossover connect to the inputs of two other amplifier channels, then you can tri-amp your speakers. Note that this will take three amplifier channels per speaker. If you are like many here, finding extra amplifiers to drive your speakers in tri-amp mode is usually not a big issue.

 

Note that you will not have the flexibility to change the crossover frequency of the woofer to the midrange, nor be able to EQ the woofer channel with the active crossover, but you will still be able to use the active crossover to EQ the most important portions of the spectrum and digitally delay the other two drivers in order to time-align your speakers.

 

Some Klipsch models (e.g., Heresy, Cornwall) have a long midrange horn and a direct radiator woofer. This means the the driver with longest delay -- the midrange driver -- will stay connected to the original passive crossovers, and the other two driver channels (tweeter and woofer) can be digitally delayed by the active crossover to time-align to the midrange.

 

EDIT: 14 Nov 2016--

New users of active crossovers looking for more detail on how to install them into the setups can refer to this thread on using Xilica active crossovers:

 

_______________________________________________________________________

 

EDIT: 14 Nov 2016--

Users of active crossovers seeking to set their parametric equalization filters (PEQs) easily and rapidly will be interested in using Room EQ Wizard (REW) to generate and optimize those semi-automatically.  A link to a tutorial thread on that subject can be found here:

 

Chris

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Great Post! I remember reading through a lot of different threads to understand the basics and then trying to google additional information, but now it's right here for everyone.

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Nice writeup...you may want to mention the need for amplifiers with no DC bias or turn on/off transients, or the need for a series blocking cap on the MF/HF units. Another advantage is the power load gets spread out so smaller amplifiers can achieve the same SPL as a single bigger amplifier (which usually means better resolution of low level detail, often perceived as cleanness or openness of sound).

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Anyone here using a bi-amp setup with just two amps and running the highs and mids together?

Jay

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Anyone here using a bi-amp setup with just two amps and running the highs and mids together?

Jay

Well if you count the highs and mids from one driver/horn.......then yes.

DrWho your customized EV DX 38 is working perfect, thank you. One day I will get a real preamp instead of the pre outs from a Ht receiver, that should be another improvement.

Very nice description there Mr cask.

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I'm convinced

WOW

Mine looks like basic 101 compared to that !

I use 2 Crown D 75's at somewhere around a whopping 70 wpc TOGETHER. [:o]

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Anyone here using a bi-amp setup with just two amps and running the highs and mids together?

Jay

I do and I'm pleased with the result....
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WOW

Mine looks like basic 101 compared to that !

I use 2 Crown D 75's at somewhere around a whopping 70 wpc TOGETHER. Surprise

I have plenty of headroom. I tried the D75's, but did not like the turnon and turnoff pops. So I sold them and went to Hafler for my HF drivers.

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WOW

Mine looks like basic 101 compared to that !

I use 2 Crown D 75's at somewhere around a whopping 70 wpc TOGETHER. Surprise

I have plenty of headroom. I tried the D75's, but did not like the turnon and turnoff pops. So I sold them and went to Hafler for my HF drivers.

Yes they do pop a little when you turn them off only in the bass bins, so I don't. They stay on, they get used everyday anyway and use less than 15 w at idle. I would try something different one day but probably get a pre-amp first.

I have each amp connected to each channel, would it be better to use one amp for the 402's and one for the bass bins ? I thought the bass bins would use more power so I split it like this, sounds great to me.

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Hey Boxx,

Can you describe your setup a little?

Jay

I have my main R & L front speakers bi-amped with a pair of McIntosh MC602 amplifiers. My speakers are capable of being tri-amped, however I don't think I have anything to gain by taking that step.

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I have my main R & L front speakers bi-amped with a pair of McIntosh MC602 amplifiers. My speakers are capable of being tri-amped, however I don't think I have anything to gain by taking that step.

He's being modest, that's bi-amped Palladiums !

I heard those without being bi-amped, first class, really nice and very pretty. [Y]

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Boxx,

What about the mids and the highs how are they connected? Are you using a passive xover with them still connected?

Jay

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Jay,

The mids and highs are connected to the speaker, directly from the amp. via two way straps at the terminal panel. No passive xover is being used. The driver engineering, on these speakers, makes it possible for supurb results, without the need for corrections in the xover network.

Boxx

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What active crossover brands/units should I use?

I haven't tried mine in this apllication (I use it for sub ED and high-pass filter), but I guess the miniDSP could be added to the list. It would the cheapest active crossover of the list. It could even be used the EQ the bass for the room using its PEQ filters. It integrates with REW.

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