Bi Amp or Quad Amp????

[Sunnybaker]

i have it in my head that i want to use 4 mono blocks in a 2speaker set up ....

is there such an devise that could separate specific frequencies (post pre amp / pre mono block) ????
in other words: CD player plugs into Pre amp. 1 interconnect (per side) coming out of my pre amp which would plug into said devise. this devise (crossover?) would separate the frequencies into two groups to match precisely with the crossover specs of the speaker. so now i have 2 interconnects (per side) coming out of the devise and connecting to the 2 mono blocks. and now each mono block is sending the exact frequencies specified by the crossover. each mono block has its own binding posts.


i fear i am exposing my real idiotness here...

 

[frommerstop]

Yes, what you’re describing is a two way active crossover. They are not uncommon, they range in price from $100 or less, all the way to tens of thousands. A bit of internet searching (or a search on this site) should yield a ton about them & how to wire up a system.

 

[twiiii]

What you really want is a mini processor.. 2 in 4 out. or 1in 4 out. You use your computer and suppled software to program the unit. But you have to own the correct speakers that are set up for true bi-amping, allowing bypassing the internal passive crossover to get the biggest advantages.

 

[donprice]

^^^^^ what they said ^^^^^

Here's a pretty short explanation of the miniDSP 2x4
https://www.minidsp.com/applications/digital-crossovers/stereo-2-way-xover

Lots of fun and easy to unplug if you decide you hate it for some reason.

 

[gadget73]

That would be bi-amp since it has 2 amplifiers per channel. Would still be bi-amped even if it was 2 stereo amps vs 4 mono amps. And yes, active crossover to split the highs from the lows is the way to do it. There are ways of getting it done using a bunch of passive parts but its honestly more likely to mangle the signal, and it won't be easily adjustable. Being able to simply tweak a control to shift crossover points or output levels is mighty convenient.

 

[Sunnybaker]

Thanks for the thoughts. i would rather not have a computer in the mix if possible. what is the basic difference between an active and passive x-over?

 

[Sunnybaker]

is this even a worthwhile endeavor? - does the sound suffer because the x-over has to separate a larger spectrum of frequencies.... is this just moving the X-over to a different placement in the chain? i guess im thinking the amps will provide a truer sound because of the limited frequencies they are having ... amplify ....

would i bypass the inherent x-over in the speakers if i were to do a 4 amp system?

 

[fill35u]

is this even a worthwhile endeavor?

Depends who you ask. You have the ability to gain a dB or two of headroom (or maximum volume), but it's a complicated and expensive way to do that. In the meantime, you'll get education and experience. Some extoll the virtues of better sound, but you're really getting into diminishing returns with the approach.
Systems with subwoofers are generally biamped, but splitting the frequency ranges at that point makes sense for multiple reasons.

- does the sound suffer because the x-over has to separate a larger spectrum of frequencies..

It's not the range of frequencies, it's what happens through the crossover point and for an octave or two on either side of it that matters. The most popular professional approach is to use fairly steep slopes, 24dB/octave, to minimize the range of frequencies affected by the crossover point, and to better utilize drivers closer to their frequency limits.

is this just moving the X-over to a different placement in the chain?

Yes. The benefits are that because the voltages and currents are so small compared to at the amplifier outputs, the crossovers can be much smaller, accurate, lower distortion, and cheaper. A huge benefit is that a line level crossover is very fast and easy to adjust, tweaking speaker level crossovers requires at least having many different components on hand to try.

i guess im thinking the amps will provide a truer sound because of the limited frequencies they are having ... amplify ...

Theoretically, yes, but the improvements should be so miniscule as to be far from audible. There are some benefits or drawbacks to using different types of amplifiers for different frequency ranges, but that's getting a bit technical.

would i bypass the inherent x-over in the speakers if i were to do a 4 amp system?

That's certainly the best way, and most likely to give you any actual sonic benefit.

Don't forget that the speaker drivers themselves have their own *acoustic* rolloffs that may contribute to the original crossover design.

 

[Sunnybaker]

thanks fill

 

[Sunnybaker]

whats the point of having two sets of terminals on the back of speakers if your just running the same signal to each set?

 

[fill35u]

whats the point of having two sets of terminals on the back of speakers if your just running the same signal to each set?

Your speakers' user manual should explain. The manufacturer is providing you with the option to both:

1. "Bi-wire", which is running two pairs of wires between one speaker and one amplifier channel. This has as much benefit as you might expect, but speaker cable companies like you to buy twice as much wire.

2. "Bi-amp", which is what you have been talking about doing, one speaker utilizing two amplifier channels. If you do it with only the speaker crossover in place, it's "passive" bi-amping, and of dubious value. If you use an active crossover further upstream in the chain, you're "active" bi-amping. If you want to purely active bi-amp, you'll need to bypass the crossover inside the speaker.

When I built my front speakers, I used *four* terminals per driver section, so I could easily active tri-amp them and bypass the internal passive crossover just by making different connections: