Speaker Frequency Info

[[DANGERDAN]]

Hi there, for the past week i have been researching about speaker technology and how it all works and have found out quite a lot so far, what i am hoping for is some help with just a few little things and hope this can turn into quite a deep discussion as it would be fun as well :P.

Ok so i am looking into buying the rf62 II from klipsch as it has the best quality's money can buy for that price, with most of the speakers i have researched they all have a average low frequency of 35-40 hz and most now go right up to 24khz. What i am confused on is why create speakers with such low frequency when the sub woofer's are best to run from 20-80hz or should the cutoff from the sub run to the 35-40 hz that the floor standing speakers can do?.
Another question for the cutoff frequency between the tweeter and woofers i understand there are different opinions about the best cutoff frequency between the two but generally the companies producing them try and get the best balance between both, What are the differences between the two if say you were to run 1khz through both the speakers would they sound different ?

Thanks.

[Nanometer]

Ahh so many questions! I'll try to answer some of them for you though.

first I recommend you read up on crossover frequencies, as I think that would answer many of your questions. Nonetheless, I too find it interesting so I think I'll talk a little bit about it. Many speakers are rated as low at 30 Hz klipsch speakers included. However that does not mean they are capable of actually playing balanced frequencies at a reasonable volume. The whole downward extension of specifically tower speakers were designed to help you pick up a subwoofer that would blend with those tower speakers. For instance-- If you pick some tower speakers that play within 3 db spec down to 40 hz, you would not want a subwoofer that would have a bottom extension down to 40 hz. In fact it wouldn't do a whole lot coming from a music point of view(movies are a different topic). You would want a sub that would well below 40 to fill in the missing gaps that the typical small tower speakers are incapable of playing. Unfortunately your question is not easily answered, and it's better answered by reading articles I think. That's about my best shot at that, but if have anything else... let me know =-p.

You last question is actually easy to answer.

All tangible objects have mass, and all those objects have a natural frequency. Bare with me, this isn't a physics lesson and it will get to the point. Actually I lied it is a physics lesson. Anyways... a system such as a speaker which is comprised specifically of a diaphragm which creates the frequency that you hear has a specific weight and damping coefficient based on the materials the diaphragm is made out of. This diaphragm will vibrate at a natural frequency and so naturally every speaker is different and has a special frequency range it is unusually good at producing.

A large speaker has more mass and that means a lower natural frequency. Similarly a small speaker has less mass and thus a higher frequency at which it resonates. The whole reason that cross over frequencies are used is to blend the speaker array together to get the best sound out of the system over the widest band of frequencies. This is done by having large speakers play low frequencies, medium sized speakers play medium frequencies and small speakers play the high frequencies. Combining this process gives the best frequency response out of a speaker array.

And yes, a small medium sized speaker playing 1000 Hz would sound very different from a large speaker or a small speaker. If that medium speaker happens to resonate at or near 1000 Hz then that speaker will play it with unusually high db levels. A very small speaker would play it poorly due to it's inadequate size and would sound normal, or even quieter than you would expect. A large speaker would play the frequency, but you would likely hear nothing as a large speaker is typically tuned to play in the range of below 400 hz of course dependently. But if we are talking a subwoofer say 12 inches, it would likely sound completely silent. This is due to its inadequacy to play those frequencies due to it's limiting design.

I hope that's followable... there's a lot of talking in there haha

[[DANGERDAN]]

You my friend are a :banana::banana::banana::banana:ing legend hahaha well done i must say and i think i fully understand the technique for the crossover frequency, basically easy way said finding the best crossover frequency between the tweeter and the mid woofer is probably finding the highest frequency the mid woofer can play with the tweeter being able to play that frequency with the best similar sounding output from both as possible at that crossover frequency. Least that's the best i can describe it :).

Might post more on stuff when my brain gets excited :P thanks man.

[Donnie27]

;4628573']You my friend are a :banana::banana::banana::banana:ing legend hahaha well done i must say and i think i fully understand the technique for the crossover frequency, basically easy way said finding the best crossover frequency between the tweeter and the mid woofer is probably finding the highest frequency the mid woofer can play with the tweeter being able to play that frequency with the best similar sounding output from both as possible at that crossover frequency. Least that's the best i can describe it :).

Might post more on stuff when my brain gets excited :P thanks man.

I tried to post info but it didn't post, wasn't saved and lost. Go to Madisound.

http://www.madisound.com/server-maint.php/index.php?cPath=35

http://www.parts-express.com/pro-sound.cfm

Not meant to build your own speakers but for info on Crossovers. 1KHz should sound like 1KHz no matter what Driver is reproducing the sound. One might be louder, but the tone should sound the same.

http://en.wikipedia.org/wiki/Piano_key_frequencies

[STEvil]

Its not a good idea to use the max or minimum frequency a driver "can" produce as your crossover point. This might be fine at 50 watts of input power, but at say 500 that driver might be compressing the output or producing horrible distortion due to inability to move fast enough or support the excursion required.

[Nanometer]

That's a good point you made.

Crossover points should actually be overlapped to reduce speaker fade (dips in the frequency output) and possible distortion. The most basic is first order which gradually steps down the frequency output based on the electronic components given(a resistor, capacitor and coil). The idea is to get a good overlap without giving too much output and not too little.

[[DANGERDAN]]

ah thats why they have it so the speakers overlap eachother by about 500mhz eg mid woofer 50hz to 2khz ,tweeter 1.5khz to 24khz

[Nanometer]

The overlap depends on the order of crossover as well. It's not as if there is an immediate cut off point, but like we said it's gradual. The higher order crossover can increase efficiency and make the frequency step off slope steeper. But like you said that's why the drivers have a maximum efficiency range. The output of the speaker array would be horrible if you ran the crossover backwards, and likely destroy the tweeter by force feeding it power it wasn't meant to handle.

[[DANGERDAN]]

Ok cool so basically there is no crossover that can be stated as the best as it depends on the speakers overall frequency to determine where the crossover should be and how they overlap, for eg when looking at the Klipsch each upper model i looked at had lower and lower crossover frequency making me think that lower crossover = better quality but in fact the minimum frequency was just improving over the models going from 55hz down to about 35hz, which required the crossover to be lowered to get the right balance again.

[Nanometer]

The reason they also lower the bass to mid crossover is to also split the power load evenly, which happens to also correlate with sound balance. Klipsch top of the line towers provide a lot of power. Most of the power is delivered at below 400 hz for typical movie or music use. Though it isn't always true, it varies depending what you are listening to. But like I said the lower cut off enables the speaker array to handle more power by taking some of the power away from the bass range speaker.

[[DANGERDAN]]

Ah i get you with the power usage, so in saying that a 2 way system (tweeter,mid woofer) would typically be better setup technology wise to use than a 3 way (Low woofer,Mid woofer,Tweeter) due to having one less crossover to play with ??

[EniGmA1987]

3-way system is better "technology". It allows the frequencies to be reproduced more efficiently and sound better overall because you have each of the speakers being more dedicated to their best frequencies.

[STEvil]

You have to be careful about the "3+ way" systems. Some manufacturers just use that to define how many drivers are in the tower and not their actual cross-over points.

[Nanometer]

To be honest a 100 way setup would be the best, but only on paper. Getting such precise components would be costly, and it just makes more sense to have tower speakers in a 2 or 3 way setup. And lets face it, there are not 100 different speaker sizes to choose from, at least not drastically different in size. The technology is no different by changing how many crossovers there are, it just changes the amount of required speakers to complete the array.

In general, my personal opinion when it comes to home theater speakers is that a 3 way setup is the best. Two way is good, and a single speaker offers the poorest performance by offering a mediocre frequency response at high output.

[STEvil]

why 100?

[Nanometer]

just some arbitrary number I pulled out of the air. Just trying to say that the most efficient system would be a system that has the most resonant frequencies in it. Though I've never personally seen that tested, I could be wrong.

[[DANGERDAN]]

very true on paper it would be the best but without the material well you get the idea :P, what about the amps that drive the speakers, if you were to drive say two identical speakers with amps that push the same power but come from two different companies, what kind of effect do different brands give off and why. (Im guessing its because of the stability of the power it pushes).

Also couldn't the amp be classed as just the power supply as it doesn't really amplify the signal it just provides the power that is required by the speakers ? just a theory.

[EniGmA1987]

Technically "power is power" and it would sound the same. However two amps with the same power ratings are NOT identical which is why you do hear a difference. One amp might be Class A, another might be Class AB, one might be Class H, and so on. That can easily change how the amp sounds. Also the capacitors can have an effect on sound. The transformer used can effect sound, although pretty much everything uses a toroidal transformer now so that isnt really an issue. If the amp is solid state or a tube amp, producing the same wattage, it would sound different. Using different circuit design would effect sound. The amp's damping factor can effect sound because if one amp has a low damping factor it cant control the speaker as well as the amp that has a good damping factor. Also one company might rate their power output differently than another company.

But if the amp was the same class, had the same transformer, was rated the same, and actually provided the same output power to the speaker, I really dont think you would hear any difference. Even with a few changes to things in the amp like different circuit design but the same class of amp, you would be very hard pressed to get it to sound different to a person.

[[DANGERDAN]]

thanks mate that was perfect :)

[STEvil]

Also dampening factor of the amplifier can be removed by adding a circuit resembling a crossover to the system. This relies heavily on the natural dampening factor that is present in the driver so if your spiders are not up to the task you could be tearing your sub (its only recommended to be used with subs) apart easily. It does help create more output at frequencies below the cutoff tuning point of the system though.