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bi-amping ar 3-a improveds.


fred

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Just for fun!

A couple of months ago i bought a pair of 3a-improveds here in Holland.(180 euro)

Since i have a Nakamichi ES-100 and a Stereo 400 which i don"t use at the moment, i'd like to bi-amp the improveds.

My question is ...how!??

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Just for fun!

A couple of months ago i bought a pair of 3a-improveds here in Holland.(180 euro)

Since i have a Nakamichi ES-100 and a Stereo 400 which i don"t use at the moment, i'd like to bi-amp the improveds.

My question is ...how!??

The 3a Improveds weren't originally designed to be bi-ampable. You need to post this question in the Mods, Tweaks and Upgrades forum.

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Just for fun!

A couple of months ago i bought a pair of 3a-improveds here in Holland.(180 euro)

Since i have a Nakamichi ES-100 and a Stereo 400 which i don"t use at the moment, i'd like to bi-amp the improveds.

My question is ...how!??

Check your messages, Fred as I sent you a memo with my email address.

They don't like talk of bi-amping on this board even though the top of the line AR-9 came from the factory bi-ampable.

Regards,

Jerry

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They don't like talk of bi-amping on this board even though the top of the line AR-9 came from the factory bi-ampable.

What we don't like here is discussions about modifying classic models, except as needed to restore original function when original parts are unavailable. Why don't you try posting something about biamping a model that came from the factory equipped for it instead of marking changes on original designs and see what happens?

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What we don't like here is discussions about modifying classic models, except as needed to restore original function when original parts are unavailable. Why don't you try posting something about biamping a model that came from the factory equipped for it instead of marking changes on original designs and see what happens?

OK, fair question!

It turns out that my original post on this board was about bi-amping an AR-3a without any modifications. That's right no changes, all original parts, yet bi-amped!!

It turns out that the three terminals common on many of the early AR's can be bi-amped without modifying anything and you get the same improvement in control and sound that you'd achieve bi-amping the top of the line AR-9's.

It seems that bi-amping a speaker WITHOUT any modifications is still a modification in the minds of some people, because (and this is precious) it was never intended to be bi-amped. That argument is as silly as saying we can't talk about using AR's in a home theater setup, because AR's were never intended to be used in a home theater.

Is this small minded and petty? Yes, I'd conclude so. Does this philosophy inspire experimentation and continued use of AR's? I'd suggest it does not.

Regards,

Jerry

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It seems that bi-amping a speaker WITHOUT any modifications is still a modification in the minds of some people, because (and this is precious) it was never intended to be bi-amped.

Well, those people are wrong and I will be the first to disagree if I see that view expressed (I may have missed it previously because I didn't have 3's and didn't read all the related posts). AR clearly identifies the purpose of the three terminals and jumper on speakers so equipped to be to disengage the woofer from the other drivers if desired.

As for experimentation with modifying the internals of the speakers, no reason why not, or there wouldn't be a forum for it. It's just not this forum.

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No need to go down this road, again!

Reasonable home theater operation of an AR-3a is within that loudspeaker's design parameters - it would not require any sort of modification, so your comparison fails on its face.

"Bi-amplifying" an AR-3a through its original crossover in the manner that you've described many, many times in the past might fail the "it's a physical modification of the loudspeaker" test, but clearly goes far beyond what any owner would normally try to do to his speaker, and therefore meets the "tweak" criterion.

It's not the same thing as unhooking the straps on an AR-9 crossover, and connecting a pair of amplifiers - a capability that was designed-into the AR-9.

And as has been pointed out by more than one individual on this forum, the nature of your described "bi-amp" set-up has some potentially serious drawbacks, and could be a pitfall for the unsuspecting.

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"Bi-amplifying" an AR-3a through its original crossover in the manner that you've described many, many times in the past might fail the "it's a physical modification of the loudspeaker" test, but clearly goes far beyond what any owner would normally try to do to his speaker, and therefore meets the "tweak" criterion.

OH, really!! And just who decides what is "clearly beyond what any owner would normally try to do to his speaker"? Do we have some standards to measure this against or perhaps you are the arbiter of normalcy?

Next, how are the amp connections to a speaker a "tweak"? What's being "tweaked"?

It's not the same thing as unhooking the straps on an AR-9 crossover, and connecting a pair of amplifiers - a capability that was designed-into the AR-9.

And as has been pointed out by more than one individual on this forum, the nature of your described "bi-amp" set-up has some potentially serious drawbacks, and could be a pitfall for the unsuspecting.

OH, really!! And just what are the serious drawbacks??

Clearly, the amps have to be common ground, but the vast, vast majority of amps ... are. There are easy tests to determine whether amps are compatible. I've used 5 different amps from 5 different manufacturers and have had zero problems bi-amping with 3 terminals.

Regards,

Jerry

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Well, those people are wrong and I will be the first to disagree if I see that view expressed (I may have missed it previously because I didn't have 3's and didn't read all the related posts). AR clearly identifies the purpose of the three terminals and jumper on speakers so equipped to be to disengage the woofer from the other drivers if desired.

Exactly, Gene!

The speakers were designed to externally separate the drivers, so why not power the drivers separately. To do this with three terminals requires amps with the common ground design and the vast, vast majority of amps are designed with common grounds.

When we connect audio patch cords between various devices and amps, the shielding on the cables ties all of those grounds together.

Regards,

Jerry

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The fact that the terminals for one side of the woofer and the midrange/tweeter section have a removable link suggests rather strongly that bi-amplification was at least considered in the original design. Same for KLH Model-6 but not for KLH Model-17. (It also considers the possibility that the woofers might one day be operated either alone or with different midrang/tweeters and this can be done, even changing its hf crossover point downward with additional external components without having to open the box.)

At the time these speakers were designed, high quality amplifiers were expensive, external low level active crossover networks not commercialy available, and frequency equalizers beyond the reach of all but millionaire consumers so they were out of the question. All that has changed drastically.

AR3/AR3a, AR2a, AR2ax can all be biamplified by removing the connecting link and powering the woofer with a separate amplifier from the midrange/tweeter section. The most important thing is that the two amplifiers must be able to have their ground wires common and operate safetly in that mode. Do not try to make the hot sides common or you may damage one or both amplifiers. The internal crossover networks will automatically channel the correct frequences to the correct drivers so you do not need or want an active crossover network in the circuit. If you have the speaker enclosures open or are willing to do that, you can change the circuit from a three wire to a four wire circuit like AR9 by removing the common link and bringing the extra wire to a separate terminal. You can also remove the links between the midrange and tweeter sections and create a 6 wire circuit for tri-amplification. Just be sure to seal the opening around the holes for the additional wires so the box remains air tight. Personally, I'd use GE silicone caulking for that.

Unlike bi-wiring there are IMO real advantages to bi-amplification and in this case even more advantages to tri-amplification. However there are pitfalls so you must be aware of them to avoid falling into one. Here's how to go about it.

You will need a separate master preamplifier. This will adjust the output of all of the power amplifiers simultaneously so that the relative loudness of each driver remains the same compared to the others. You can used integrated amplifiers or receivers in place of power amplifiers. They should all be able to handle 4 ohms. Each power amplifier must have its own volume control or at the very least those for the midrange and tweeters so that the relative loudnesses can be adjusted independently. If you tri-amplify, you can bypass the pesky level controls in the crossover networks and if you want absolute perfection, replace them with fixed resistors for their indicated flat settings for your speakers as specified elsewhere on this site in the library.) This will allow the volume contols on the power amplifiers to be used as a substitute for the midrange and tweeter controls. You will need to be aware of whether or not the amplifiers invert phase or not relative to each other. This is easy to determine with a 1 1/2 volt battery at the input and an analog voltmeter or a spare speaker driver large enough so that you can observe its motion connected to the output. With the speaker connected in phase to the output, connect the negative battery terminal to the input ground and touch the input hot lead to the positive terminal of the battery. If the speaker moves forward and then back the system does not invert. If it moves back and then forward it does invert. Keep the volume setting low so that you do not damage the speaker. You can also use a series resistor to limit output to the driver for this test. If one amplifier inverts and the other doesn't and you have to make the correction by reversing the speaker terminals to one of them to preserve proper relative phasing so you will have to go to the four or six wire circuit I described above or you will risk damaging one or both amplifiers.

High quality high powered solid state amplifiers can usually handle very difficult electrical loads without any problem and if this is what you have, you may not notice any improvement in sound. In your own setup, there is no way to know until you try it. One advantage especially in triamplifying is that you can adjust the loudness of the drivers individually in a way that will allow you to have the same relative loudness of the drivers to each other for the left and right channels. This is done by operating one amplifier pair at a time and listening to a monophonic signal. This is much harder to do with the controls on the back with only a single stereo amplifier. You can also adjust the relative volumes of the drivers from a distance and listen to the effect of changing them much more easily than by adjusting them with the pots on the back of the speakers. BTW, you may want to consider fusing the individual drivers while you are at it. Some amplifiers like AR have fuse holders built in. You can also add an equalizer for even greater control flexibility to the system. Be patient. It is my experience that it takes considerable time to optimize these complex arrangement so don't expect immediate gratification. Mark gain settings you like so that you can go back to them easily.

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You will need to be aware of whether or not the amplifiers invert phase or not relative to each other. This is easy to determine with a 1 1/2 volt battery at the input and an analog voltmeter or a spare speaker driver large enough so that you can observe its motion connected to the output.

Good post, Soundminded!

Lots of good stuff here. Just want to mention two things. First, there is a third way to test relative phase of the amps and that is with a dual trace scope.

Secondly, in my previous configuration I used an amp that had a "tone flat" switch. Purpose of this switch was to by-pass the tone controls. It did that, but in the process it reversed phase. So, I had a way to reverse phase on the mids/tweeters relative to the woofers via a simple "flick of the switch".

I flicked that switch hundreds of times and the results were most confusing. First off, you must listen very carefully, because the differences are very minor and in many cases non-existent. That is, in many cases I could hear no difference.

The differences I did hear tended to be in stereo separation and the high frequencies. That is, in one position high frequencies were a little clearer and stereo separation tended to be greater. So far ... so good!

Now for the bad news ... the results were NOT consistent for a switch setting. The results were always consistent for a particular track, but when I switch CD's or tracks the results were all over the place. Here is what I’ve subsequently learned after listening to all kinds of music:

1. sometimes there is NO difference in resulting sound regardless of the phase

2. sometimes stereo separation and high frequencies are BETTER when the signals are OUT of phase

3. sometimes stereo separation and high frequencies are BETTER when the signals are IN phase

How can this be???

I mean, it doesn’t make any sense.

Companies have spent significant sums designing speaker systems to keep everything in phase, yet sometime it sounds better when … the signals are out of phase??!!

Is it possible the sound engineers when “enhancing” the audio signals to make the cd masters, screw up the phase relationship between the bass and the high frequencies?

If this happens, then when I say it sounds better “out of phase” what’s really going on is that I have put the phase back in line.

This is NOT neat … it’s NOT tidy and it makes no sense.

Regards,

Jerry

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Onplane,

I've had similar experiences and to be honest, do not know the right answer. That being said, I'll propose a hypothesis.

If the recording is mono or nearly mono, perhaps phase will have little or no effect.

If the recording is in stereo but was recorded with minimal channel separation, being out of phase might separate the channels for a larger sound stage.

If the recording has a respectable soundstage, ATA recorded properly, throwing the channels out of phase will destroy the soundstage resulting in a left and right without a middle.

It's 6:35 AM and i just arrived in the office a few minutes ago. Don't check my spelling to closely.

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Guest rbrumett
Onplane,

I've had similar experiences and to be honest, do not know the right answer. That being said, I'll propose a hypothesis.

If the recording is mono or nearly mono, perhaps phase will have little or no effect.

If the recording is in stereo but was recorded with minimal channel separation, being out of phase might separate the channels for a larger sound stage.

If the recording has a respectable soundstage, ATA recorded properly, throwing the channels out of phase will destroy the soundstage resulting in a left and right without a middle.

It's 6:35 AM and i just arrived in the office a few minutes ago. Don't check my spelling to closely.

Also sometimes either by misstake or on purpose the mics(one or more) have been miiswired(out of phase). That could be one of the reasons the sound changes.

Thanks,

Rick Brumett

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"So, I had a way to reverse phase on the mids/tweeters relative to the woofers via a simple "flick of the switch"."

The explanation of why you sometimes heard a difference is quite simple and straightforward. You altered the system frequency response in the crossover region. You created different patterns of constructive and destructive interference at every point in space. If two drivers operating at the same frequency were in the same physical space and the time delay between the application of the electrical signal and the mechanical response were the same, they would arrive at the same point in space at the same time and their amplitudes would add constructively. This would add 3db to their output. Well that's almost true, at least it would be on axis. But as the drivers are located in a different point in space their acoustical fields will reinforce and cancel each other out because their acoustical waves from the same electrical excitation arrive at slightly different times. The greater the spacing relative to the wavelength, the greater this effect. If the two drivers are at the same loudness, the reinforcement can be no more than 3db but the cancellation can be infinite, that is they can cancel each other out completely. Imagine two rocks thrown in a still pond. If they land together at the same place at the same time, you will see one smooth ripple going outward. But if they land in two different places at the same time, you will see a complex pattern of interference where the ripples intersect. And in real speaker systems, the time delay between input and output of each driver is different so imagine one rock hits the water before the other. Bad as that is, what you are doing by reversing phase is to make one driver push while the other one is pulling when they are out of phase. What makes it even more complicated is that the degree to which this is true is also dependent on the exact frequency, that is phase angle difference between the two drivers is frequency dependent in the crossover region. Speaker designers experimented with these phenomena both electrically with various filter configurations and mechanically with various geometric driver positioning and each variant was heralded as a breakthrough in time alignment. Linkwitz Riley for example did not eliminate this problem but designed a filter arrangement which localized the place in space where cancellations were worst at a spot a listener was not likely to be. Ultimately, unless you get to the equivalent of a pulsating sphere, the problem has no solution, you cannot eliminate this effect completely.

Anyway, the effect you hear is due strictly to the resulting changes in frequency response this effect creates.

There has been much discussion about "absolute phase" among audiophiles as well. This relates not to driver to driver phase relationships but to the overall phase of the system from input to output which can be reversed 180 degrees. This is a controversial discussion that should have its own topic if there is any interest. Personally, I've given it some thought and as a result don't concern myself with it because whatever differences might be audible are IMO not significant. Others disagree strongly.

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"So, I had a way to reverse phase on the mids/tweeters relative to the woofers via a simple "flick of the switch"."

The explanation of why you sometimes heard a difference is quite simple and straightforward. You altered the system frequency response in the crossover region. You created different patterns of constructive and destructive interference at every point in space. If two drivers operating at the same frequency were in the same physical space and the time delay between the application of the electrical signal and the mechanical response were the same, they would arrive at the same point in space at the same time and their amplitudes would add constructively. This would add 3db to their output. Well that's almost true, at least it would be on axis. But as the drivers are located in a different point in space their acoustical fields will reinforce and cancel each other out because their acoustical waves from the same electrical excitation arrive at slightly different times. The greater the spacing relative to the wavelength, the greater this effect. If the two drivers are at the same loudness, the reinforcement can be no more than 3db but the cancellation can be infinite, that is they can cancel each other out completely. Imagine two rocks thrown in a still pond. If they land together at the same place at the same time, you will see one smooth ripple going outward. But if they land in two different places at the same time, you will see a complex pattern of interference where the ripples intersect. And in real speaker systems, the time delay between input and output of each driver is different so imagine one rock hits the water before the other. Bad as that is, what you are doing by reversing phase is to make one driver push while the other one is pulling when they are out of phase. What makes it even more complicated is that the degree to which this is true is also dependent on the exact frequency, that is phase angle difference between the two drivers is frequency dependent in the crossover region. Speaker designers experimented with these phenomena both electrically with various filter configurations and mechanically with various geometric driver positioning and each variant was heralded as a breakthrough in time alignment. Linkwitz Riley for example did not eliminate this problem but designed a filter arrangement which localized the place in space where cancellations were worst at a spot a listener was not likely to be. Ultimately, unless you get to the equivalent of a pulsating sphere, the problem has no solution, you cannot eliminate this effect completely.

Anyway, the effect you hear is due strictly to the resulting changes in frequency response this effect creates.

There has been much discussion about "absolute phase" among audiophiles as well. This relates not to driver to driver phase relationships but to the overall phase of the system from input to output which can be reversed 180 degrees. This is a controversial discussion that should have its own topic if there is any interest. Personally, I've given it some thought and as a result don't concern myself with it because whatever differences might be audible are IMO not significant. Others disagree strongly.

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