Bi-amping (yes I know.. I know.. sorry)

Glowrdr

So I am not interested in doing this AT ALL, this is just more of a learning question for myself. I understand that bi-amping is generally not done correctly, and is only valuable in more extreme circumstances.

The thing that I'm curious about (not that it really matter, but again, just for my own knowledge); how does it actually work? Just for extreme simple terms, lets say a 2-way crossover. (Maybe I need to understand the x-over concept in order to see the big picture)

Is it 100% power out of receiver > into crossover > 50% high, 50% low frequency (or 30/70, 60/40 however the crossover is set?)

Or is it best to consider it power rather than percentage? Like 100 watts > into crossover > 100 watts high, 100 low (so the crossover doesn't change the power distribution)

Not looking to start any discussions of do or don't, just one of those stupid questions that I feel is valid, that popped into my head so I thought I'd ask. Thanks in advance - gotta get my learn on. lol

While I am here asking, is the premise of bi-wiring that speaker wire is better grade than a stamped brass plate? This is what I'm expecting for an answer, but if I'm wrong I'd like to know as well.

Outfitter03

Bi-amping is done with TWO, that is 2 separate amplifiers. One amplifier is used to send the drive signal to the tweeter circuit and one amp is used to send the signal to the Mids and Bass drivers in your Monitor 70 example.

The inputs to the crossovers are two separate circuits which you connect to with the binding posts. In the monitor 70 the tweeter is all that is driven with the top set of binding posts, the 2 Mid drivers and two bass drivers are driven by the bottom set of binding posts.

I don't know the power requirements to drive, but my guess would be >90% to drive the Mid and Bass 6 1/2 inch drivers and <10% to drive the 1" tweeter, depending on music (input signal) of course. Many who practice bi-amping connect an active crossover to the drivers and do not use passive crossover components. This is not at a beginner level IMHO to make this work successfully.

Bi-wiring is either done with specifically manufactured bi-wire cables and some people run two sets of speaker cables. Frequently in either the purchased Bi-wire sets or in the two sets of speaker cables the wire and wire gauge is tweeked to suit the frequency range. The lower set of cables for the Mids and Bass are larger gauge and the tweeter wire gauge is smaller.

A less expensive route is to make or buy jumpers to replace the brass ones from the factory. They should be of the same quality range as your speaker cables. Brass in the signal path is never a good thing and the less there is the better!:biggrin:

Big Dawg

Glowrdr wrote: »

So I am not interested in doing this AT ALL, this is just more of a learning question for myself. I understand that bi-amping is generally not done correctly, and is only valuable in more extreme circumstances.

The thing that I'm curious about (not that it really matter, but again, just for my own knowledge); how does it actually work? Just for extreme simple terms, lets say a 2-way crossover. (Maybe I need to understand the x-over concept in order to see the big picture)

Is it 100% power out of receiver > into crossover > 50% high, 50% low frequency (or 30/70, 60/40 however the crossover is set?)

Or is it best to consider it power rather than percentage? Like 100 watts > into crossover > 100 watts high, 100 low (so the crossover doesn't change the power distribution)

Not looking to start any discussions of do or don't, just one of those stupid questions that I feel is valid, that popped into my head so I thought I'd ask. Thanks in advance - gotta get my learn on. lol

While I am here asking, is the premise of bi-wiring that speaker wire is better grade than a stamped brass plate? This is what I'm expecting for an answer, but if I'm wrong I'd like to know as well.

First of all, you seem to be confused by the terminology. Bi-wiring is different than bi-amping. Note that "bi" means two. So, Bi-amping means using two amps, while bi-wiring means using two wires.

Bi-amping can be done in a couple ways. The first is where you use a different amp for each speaker (vertical bi-amping). The second method is where one amplifier is used to power higher frequency driver(s), and another amp to drive lower frequency driver(s) (horizontal bi-amping).

Bi-wiring means running wires separately to the high and low frequency drivers from the same amp.

Bi-amping can offer many benefits if done correctly with appropriate gear. bi-wiring may or may not offer any benefit (I've never heard a difference).

Use the search function here on CP, and Google it as well - you'll find plenty to read on the subject.

Glowrdr

Sorry for the confusion - I actually do know the difference in each, just happened to ask both questions in the same thread.

As for the bi-wiring, the main question was just "Is running speaker wire from the upper set of binding posts to the lowers any better than the stock brass plate" (I just worded it as more of a thought rather than a direct question)

For bi-amping - I know it is done with 2 amps as well. But if I take (2) 100 watt amps, and wire them to the same speaker, I know this does not equal twice the power (unless bridging). From what I believe, it just isolates noise from the high's/lows if using an active crossover. For a passive crossover, this does nothing correct?

I guess I did not/was not aware that the crossover had 2 input points (being top and bottom posts) but that makes obvious sense now that I put 2+2 together of why there are different posts to begin with.

So as originally stated - I do understand the generalities of audio, I was just trying to learn a little more about the nitty gritty of HOW it actually works.

Just for an example as used above (maybe I over simplified it to a non-functioning scenerio before). Take the above guestimate of 10/90 upper/lower. Hook 1 100 watt amp up like normal, with the jump plate in place. Does that mean the crossover diverts 10% of the power to the highs, and 90% of the power to the lows? Or does it just filter out the sound so only the top 10% of the frequency plays from the tweets?

Add bi-amping to the mix. Same scenerio, same equipment. What does this do for the speaker? Anything? I feel that I should know there wouldn't be any additional volume, just a seperation of frequencies? Hopefully someone can see where it is that I'm getting confused. I guess I'm not seeing the "ah-ha" moment in the chain where I understand what is happening at the crossover level (or possibly just after?)

Big Dawg

Let me see if this helps. Without crossovers, all speaker drivers are fundamentally full-range speakers, although they have been engineered to optimally reproduce a specific segment of the sound spectrum (i.e, tweeters are designed to reproduce high-frequency sounds). The primary function of the crossover is to send only the desired frequencies to the appropriate drivers. Crossovers are also designed to send the right balance of power to each driver so that the volume of sound from the lowest frequencies to the highest is constant (a flat response curve). There is no magic ratio - each speaker design requires a unique combination to account for the specific drivers and cabinet.

Glowrdr

Ok - so that helps. Crossovers both dictate frequency (which I knew), and they ALSO distribute power? That's what I wasn't completely clear on. I know there wasn't an across-the-board answer as there never is for much. I just wanted to put it into something "physical" so a response could be generated.

Still a little confused as to what benefit bi-amping really has outside of a bridged scenerio. I could always Wiki it, but I'd get a piece written by stephen hawking that some 12 year old chinese kid would have to interpret for me. I was hoping there was a way to "dumb it down" for me, with the understanding that I grasp the concept, just not the details.

Maybe I'm to the point that I know what can be known, and anything more would ask that I know about the field itself? I can go on all day about the differences between a router and a switch. I just haven't fully engulfed the fundamentals behind a crossover for some damn reason. lol

Outfitter03

The passive crossovers filters the frequencies sent to the various drivers. The filtering is done using an interaction of resistors, capacitors and inductors. Inductors are also called coils or chokes. They are in the simplest form coils of wire.

There are several schematics in the vintage speaker section that you can look at to get a basic idea of what Polk crossovers look like.

The crossover points (frequency) is not a hard line but a curve with a roll off or reduction at a certain rate. The idea is to make a smooth transition from one type of driver such as the Mids to the Tweeter with enough crossover that their is a smooth or linear transition as the frequency increases without peaks or dips in certain frequency ranges.

Your next set of questions are very difficult to answer without you spending some time learning basic circuit theory. The amplifier provides an AC signal which is an AC potential measured with units called volts. The power consumption of the speaker drivers is a physical characteristic of driver itself given the level of AC signal and the crossover components designed by the manufacturer. For power to be consumed, current must flow through the driver. This is measured in amps. For a given voltage level which is determined by the signal (music) and level (volume knob) on the preamp the drivers will pull as much current as they need to operated to their full potential. This is why you will read that having too little power is much worse than too much. At normal listening levels the speakers will stay within their ratings and perform well.

To overpower the speakers you need to have the volume very high and with most quality speakers you are now at a decibel level that is damaging to your hearing.

Transients in the music will create spikes of power that an amp with a smaller power supply is unable to respond to and thus you will not hear the impact or dynamics that would be available with a more powerful amp. If the amp is being asked to provide more current than it is capable of sustaining it will start clipping off the peaks or transients in the audio signal and the most susceptible component is the tweeter.

Vertical bi-amping as described above by Big Dawg would give the increase in current delivery. An example using Parasound Amps would be to use two HCA-750 amps each providing 75 watts of high current power, with one amp powering each Monitor 70. This instead of say selling those amps and buying one HCA-1500 providing 205 watts of power and running both speakers off of one amp. The wiring of bi-amping is a bigger hassle, but if you already own two identical amps, you would see increased performance.

Glowrdr

Ok - I think that made the most sense. In the most basic definition, you're just adding amperage correct? Which in turn gives you more reserves, since it is a pull type scenerio, rather than a push.

I did take an electronics class ions ago, so I do understand the whole "it's not the voltage that'll kill ya, it's the amperage"

Same theory in speakers I assume. Or one could even go to the straw theory. The straw (watts) never changes, it's the size of the glass (amps) once you start drinking. (I realize this design has many flaws, but it's enough to get me to understand the deeper aspect of it, if in fact I am on the right track)

Outfitter03

You got it. This applies to all of the electronic audio components. This is why people sometime judge the units by weight because this is a good indication of the size of the power supply transformer. Another thing that better units have is right sized power supply smoothing capacitors. You will see this listed as having a capacitance of 40,000uf in the power supply. These capacitors act as a battery or surge bank to provide power for those current transients.

Michael8it

I am looking at doing the same thing on a pair of RTA12's - I am debating BI-amp vs rebuilding the crossovers. Any opinion on which is better? I read some fairly compelling arguments for why you would want to Bi-amp, but...... I still am not sure I see the value.

Glowrdr

Bi-amping is really only beneficial if you are using two seperate amps (or more inportantly 2 seperate power supplies). Using the same AVR, and using 2 channels per speaker instead of 1 only consumes more resources from the power supply since it is shared.

I've never worked on crossovers, but I've heard plenty of discussions about rebuilding/recapping crossovers. Should be able to find some useful information in the DIY section I'd believe.

**Sorry - just read your post again along with your sig, and I may not have been telling you anything new. But I still think your best option would be a x-over rebuild. I doubt you're having any issues with contaminated feeds into your speakers that you'd need to seperate frequencies outside of the cabinet itself.

Gatecrasher

Glowrdr wrote: »

So I am not interested in doing this AT ALL, this is just more of a learning question for myself.

Not looking to start any discussions of do or don't, just one of those stupid questions that I feel is valid, that popped into my head so I thought I'd ask. Thanks in advance - gotta get my learn on. lol

Why not try it? What's to lose?

Let your ears be the judge. If your AVR has bi-amp capability, it is a quick and easy thing to try. You don't need to have mega-buck speaker wires to try it. Whether or not you want to call passive bi-amping from an AVR "bi-amping" depends on your definition and how argumentative you want to be.

There's no denying passive bi-amping as per the Pioneer instructions for my 10 channel ICEpower AVR made an improvement in my system. A very noticeable improvement.

The connecting "bars" are off my Polks for good.

Here's what "Home Theater" magazine says about the Pioneer SC ICEpower receivers:

"The SC receivers....... use the latest in highly efficient, Class D switching amplifiers, in this case from ICEpower. Pioneer calls its implementation of this technology Direct Energy High Fidelity Class D.

You can use the amplifier channels in several ways, including biamping which is designed to biamp ..........separate full-range channels."

Michael8it

It would be quite that simple for me..... But Possibly still could be done. I would need an active crossover. I found one at Marchand that may fit inside my Carver CT-7. I am waiting on measurements from them to see if this would fit. My cost: $80.00. Then I would have two outputs on my Preamp: one for Mid-bass, one for the tweeter.

Here is where I need help: Do I run the same power to both?

TNRabbit

There's TONS of misinformation flying around here. "

This is a good, accurate read on biamping:
http://sound.westhost.com/bi-amp.htm
http://sound.westhost.com/bi-amp2.htm