Ok, so my "cancelling out" description was wrong. In a proper crossover, the two outputs are exactly out of phase and so the two outputs can be thought of as "canceling out" at that frequency. That's sort of what I was thinking that you were thinking.
Anyway good. The gap will just increase the impedance around the center frequency and so it won't load the amp more at that frequency, it will load it less.
If by proper you mean 2nd order, that's correct, they will be 180º out so you often see the tweeter run reversed polarity to regain that dropout.
Did you say good?
Sounds like he is refering to auto sound. Impedance load of a 4Ω stable power amp / radio does not mean source impedance. That would be much lower. Add in an car woofer/subwoofer and tweeter and wants to make a 2way out of it with a 8Ω crossover. Giagantic hole in the middle sound. Less load on the amp, but vastly reduced acoustic output at this range of frequencies.
Perfection is farthest from this, like a whole different system of physics unknown to mankind.
Perfection is farthest from this, like a whole different system of physics unknown to mankind.
With a statement like that, I will have no hesitation to close this thread as trolling.
Your call.
What?! Why is this trolling?
If you really *must* know I will tell you. I just thought I would spare everyone a treatise on electric guitar distortion.
I'm making a "pignose" amp for electric guitar out of spare parts laying around. These are little 2 watt push pull amps with interstage transformers. When overdriven they can be quite bluesy and sound surprisingly good. In my case I'm making a "Deacy" amp which is basically a transistor radio in a bookself speaker with a 1st order passive crossover. With the right Germanium transistors the distortion from these amps is intense and yet smooth (think Queen lead guitar). But there's no tone control on this thing and one of the problems with distorted guitar is that it sounds obnoxious if all frequencies are present. That's why guitar speaker frequency responses (I bet you didn't even read this far) are very non-flat. But of course I'm using 4 ohm 3 watt speakers salvaged from a set of Logitech powered desktop speakers. These have very uninteresting frequency responses. So I thought I would add a switch to alter the load on the crossover and create a dip in the response. For heavily distorted guitar that really cuts down on the bark. Mid scoop "shape" controls are common on solid state amps. So just like transformer hysteresis smears transients or how the LFOs in a CS-80 synth waver or how the coupling cap charges up in a gain stage to make an envelope filter, perfect is not always good.
miallen, you came into a forum with some of the most intellectual on the subject and are playing games.
With comments like:
This would be like cockily walking up to Einstein and asking him if he knows anything about time dilation.
and more...
this ^ one is a real gem.
When querried as to the point / application you refuse to answer repeatedly and make nonsense comments like:
If you want help ask for it straight up and we will. You are dealing with adults here, most whom have children older than you, heck some might have grandchildren older than you. Respect begets respect so show some.
With comments like:
This would be like cockily walking up to Einstein and asking him if he knows anything about time dilation.
and more...
this ^ one is a real gem.
When querried as to the point / application you refuse to answer repeatedly and make nonsense comments like:
If you want help ask for it straight up and we will. You are dealing with adults here, most whom have children older than you, heck some might have grandchildren older than you. Respect begets respect so show some.
I find it difficult to believe you had the skill to build a small amp from spare parts, yet don't grasp the most basic aspects of crossovers.
Also, your question doesn't match your description. If you have a simply small basic amp built onto a speaker, they why the original question? You were talking about, if I remember correctly, two tweeters and two woofers. How does that come into play.
This is real straight forward, I provided you with a link to an on-line Crossover Calculator, make a crossover that fits your speakers.
I think you are one of those people who has just enough information to be dangerous, though I confess we've all been there at one point or another.
If you want straight forward answers, then ask straight forward question, and provide an explanation of context for the question. Despite 3 pages of discussion, I don't, and I doubt anyone else does, have any idea of what you are talking about.
What is it you are trying to do? (with context)
What is it you need to know?
At it's peak, crossover design if very complex and not for the faint of heart. At its most basic, it is pretty straight forward, you want the reactive component (capacitor or coil) to be the same impedance as the speaker at the crossover. From that basic point, you can refine the design to the limits of your ability.
For example, you can assume generic/nominal 8 ohms (or 4 ohms in your case), and design around that.
Alternately, you can put in a bit of work and determine the actual impedance of the various drivers at the crossover frequency and use that impedance number to determine the components for the crossover.
Those are the two most fundamental steps in crossover design; the bottom two rungs on the ladder. From there, it gets complicated.
1.) Context.
2.) What is it you are trying to achieve?
3.) What is it you want to know?
As to the original question, that has been answered more than once, and very clearly. When you put 4 ohm speakers on an 8 ohm crossover, the crossover points will shift, one upward, one downward, leaving a large GAP in the frequency response.
In my example, you will have frequency response from 20hz to 500hz, then a big empty gap up to 2000hz, where the frequency response will begin again. That is as straight forward an answer as it is possible to give.
THAT is the answer to your original question.
Steve/bluewizard
Also, your question doesn't match your description. If you have a simply small basic amp built onto a speaker, they why the original question? You were talking about, if I remember correctly, two tweeters and two woofers. How does that come into play.
This is real straight forward, I provided you with a link to an on-line Crossover Calculator, make a crossover that fits your speakers.
I think you are one of those people who has just enough information to be dangerous, though I confess we've all been there at one point or another.
If you want straight forward answers, then ask straight forward question, and provide an explanation of context for the question. Despite 3 pages of discussion, I don't, and I doubt anyone else does, have any idea of what you are talking about.
What is it you are trying to do? (with context)
What is it you need to know?
At it's peak, crossover design if very complex and not for the faint of heart. At its most basic, it is pretty straight forward, you want the reactive component (capacitor or coil) to be the same impedance as the speaker at the crossover. From that basic point, you can refine the design to the limits of your ability.
For example, you can assume generic/nominal 8 ohms (or 4 ohms in your case), and design around that.
Alternately, you can put in a bit of work and determine the actual impedance of the various drivers at the crossover frequency and use that impedance number to determine the components for the crossover.
Those are the two most fundamental steps in crossover design; the bottom two rungs on the ladder. From there, it gets complicated.
1.) Context.
2.) What is it you are trying to achieve?
3.) What is it you want to know?
As to the original question, that has been answered more than once, and very clearly. When you put 4 ohm speakers on an 8 ohm crossover, the crossover points will shift, one upward, one downward, leaving a large GAP in the frequency response.
In my example, you will have frequency response from 20hz to 500hz, then a big empty gap up to 2000hz, where the frequency response will begin again. That is as straight forward an answer as it is possible to give.
THAT is the answer to your original question.
Steve/bluewizard
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