Sy,
THanks yet again... I've learned a lot from you lately about speaker stuff!
I was hoping that the zobel wouldn't affect the driver response... I take it that, by affecting the crossover response, you mean that it is changing the impedance the crossover is "looking into" (which is the point of the zobel in the first place, correct?).
Steve
THanks yet again... I've learned a lot from you lately about speaker stuff!
I was hoping that the zobel wouldn't affect the driver response... I take it that, by affecting the crossover response, you mean that it is changing the impedance the crossover is "looking into" (which is the point of the zobel in the first place, correct?).
Steve
Yes, exactly. The response of a crossover is highly load-dependent (duh!). Change the load, you change the response.
If you don't have one already, I'd highly recommend one of the numerous speaker/crossover CAD programs. You can model stuff like that lickety-split, and you then have the capability to move beyond using that RC circuit as merely a Zobel. I use CALSOD, but it's got an old, clunky user interface. Others will, I'm sure, have better recommendations.
If you don't have one already, I'd highly recommend one of the numerous speaker/crossover CAD programs. You can model stuff like that lickety-split, and you then have the capability to move beyond using that RC circuit as merely a Zobel. I use CALSOD, but it's got an old, clunky user interface. Others will, I'm sure, have better recommendations.
Yes, the Zobel does have an effect on frequency response of the driver - that's why it is used 
Due to the inductance of a voice coil in larger drivers (i.e. mids and bass), this alters the impedance of the driver. Higher frequencies see a higher impedance than lower frequencies with inductors. "Resistance" (to an electrical engineer) only refers to "true" resistance - which is only half of the picture.
Impedance is broken into two directions - real and imaginary. The real axis is the x-axis and the imaginary is the y-axis. Real impedance represents true resistance - a pure resistor. Imaginary is represented by capacitors (negative imaginary) and inductors (positive imaginary). Generally, negative real resistance isn't referred too... so for simplicity we'll leave it out here.
Now, the high frequencies are "impeded" by inductors, and capacitors are seen as no resistance (or short) by high frequencies. Using design formulas (basic textbook or advanced), one can calculate the values where the impedance of the inductor begins to effect the response of higher frequencies. This is where the Zobel comes in. The capacitor looks like a short circuit in the Zobel network to high frequencies, so they basically see just a resistor (in the Zobel network) as the path to ground. This is normally chosen as the magnitude of the impedance of the woofer (magnitude and angle represent the vector of impedance - real and imaginary axis).
So the high frequencies have the option of taking a high impedance route through the woofer (sometimes up to 30 or 40 ohms of impedance - magnitude) OR they can just go through the low resistance resistor. Because the nature of electrons is to take the simplest path, they go through the Zobel network. This gives the image that the woofer has a flat impedance load for the amplifier.
If the high frequencies went through the woofer (asuming no Zobel), then they would be going through a higher impedance which would cause the magnitude of the signal at high frequencies to be reduced, thus causing lower output of high frequencies through the driver.
The equations for the Zobel are indeed usually oversimplified - experimentation is the best way to go about it, but even using the textbook values will get your crossover a much flatter response. Good luck, and hope this long winded explanation helped -
Due to the inductance of a voice coil in larger drivers (i.e. mids and bass), this alters the impedance of the driver. Higher frequencies see a higher impedance than lower frequencies with inductors. "Resistance" (to an electrical engineer) only refers to "true" resistance - which is only half of the picture.Impedance is broken into two directions - real and imaginary. The real axis is the x-axis and the imaginary is the y-axis. Real impedance represents true resistance - a pure resistor. Imaginary is represented by capacitors (negative imaginary) and inductors (positive imaginary). Generally, negative real resistance isn't referred too... so for simplicity we'll leave it out here.
Now, the high frequencies are "impeded" by inductors, and capacitors are seen as no resistance (or short) by high frequencies. Using design formulas (basic textbook or advanced), one can calculate the values where the impedance of the inductor begins to effect the response of higher frequencies. This is where the Zobel comes in. The capacitor looks like a short circuit in the Zobel network to high frequencies, so they basically see just a resistor (in the Zobel network) as the path to ground. This is normally chosen as the magnitude of the impedance of the woofer (magnitude and angle represent the vector of impedance - real and imaginary axis).
So the high frequencies have the option of taking a high impedance route through the woofer (sometimes up to 30 or 40 ohms of impedance - magnitude) OR they can just go through the low resistance resistor. Because the nature of electrons is to take the simplest path, they go through the Zobel network. This gives the image that the woofer has a flat impedance load for the amplifier.
If the high frequencies went through the woofer (asuming no Zobel), then they would be going through a higher impedance which would cause the magnitude of the signal at high frequencies to be reduced, thus causing lower output of high frequencies through the driver.
The equations for the Zobel are indeed usually oversimplified - experimentation is the best way to go about it, but even using the textbook values will get your crossover a much flatter response. Good luck, and hope this long winded explanation helped -
I guess to rephrase my question, and to clarify:
When designing a crossover and using impedance compensation (zobel) to flatten the impedance the crossover is designed for, does it affect the response (with no crossover- only driver with zobel) of that driver. In other words, do you then have to compensate for anything in your crossover (not counting the flattened impedance curve)
From Sy's explanation, the answer to that is no (and I think this is what Tieftoner was getting at in a longer way).
To rephrase one more time- does the zobel change the voltage sensitivity of the driver? Being that it is a parallel circuit, I would say no. Correct?
Thanks for tolerating my thick-headedness.
Steve
When designing a crossover and using impedance compensation (zobel) to flatten the impedance the crossover is designed for, does it affect the response (with no crossover- only driver with zobel) of that driver. In other words, do you then have to compensate for anything in your crossover (not counting the flattened impedance curve)
From Sy's explanation, the answer to that is no (and I think this is what Tieftoner was getting at in a longer way).
To rephrase one more time- does the zobel change the voltage sensitivity of the driver? Being that it is a parallel circuit, I would say no. Correct?
Thanks for tolerating my thick-headedness.
Steve
Sorry - misunderstood you. Now I get it 
No, the Zobel won't alter the actual response of the driver. Because the Zobel is in parallel with the woofer, the woofer and the Zobel network will both have the same potential across them... thus, the output response of the driver itself will not change.
In detail: Because the driver will see the same voltage (whether the Zobel is there or not), it will draw the same amount of current through the voice coil as a function of the unchanged impedance of the voice coil. And because this current doesn't change through the coil, the magnetic field that is incurred to move the cone doesn't change, and thus the acoustic output of the driver doesn't change. Wow - hope you can follow that...
Initially, one might think that there will be additional current (power increase) need from the amplifier, because the impedance of the "woofer load" that the crossover sees has changed. There is a lower impedance witht the Zobel, thus drawing more current from the amplifier. Is this true? No. Just wanted to point it out, I guess. The reason the power requirement from the amp won't change is mostly because the crossover will be presenting a high impedance load to the higher frequencies for the woofer network... so, the amplfier really never sees much of the actual woofer impedance - the amp just sees (for the most part) the impedance of the woofer crossover network. The load for high frequencies is represented as the tweeter. Boy, that was kinda confusing - hope I didn't create extra confusion...
nobody special: Hopefully, you'll take my woofer recommendations into consideration from your other post about the P17's... Good luck with this project - and I look forward to seeing/reading the reasults!
Best wishes,
No, the Zobel won't alter the actual response of the driver. Because the Zobel is in parallel with the woofer, the woofer and the Zobel network will both have the same potential across them... thus, the output response of the driver itself will not change.
In detail: Because the driver will see the same voltage (whether the Zobel is there or not), it will draw the same amount of current through the voice coil as a function of the unchanged impedance of the voice coil. And because this current doesn't change through the coil, the magnetic field that is incurred to move the cone doesn't change, and thus the acoustic output of the driver doesn't change. Wow - hope you can follow that...
Initially, one might think that there will be additional current (power increase) need from the amplifier, because the impedance of the "woofer load" that the crossover sees has changed. There is a lower impedance witht the Zobel, thus drawing more current from the amplifier. Is this true? No. Just wanted to point it out, I guess. The reason the power requirement from the amp won't change is mostly because the crossover will be presenting a high impedance load to the higher frequencies for the woofer network... so, the amplfier really never sees much of the actual woofer impedance - the amp just sees (for the most part) the impedance of the woofer crossover network. The load for high frequencies is represented as the tweeter. Boy, that was kinda confusing - hope I didn't create extra confusion...
nobody special: Hopefully, you'll take my woofer recommendations into consideration from your other post about the P17's... Good luck with this project - and I look forward to seeing/reading the reasults!
Best wishes,
Thanks... I do get it now.
I usually have to talk through these things, and then it becomes clear. As soon as I typed about the zobel being in parallel with the woofer, it all made sense (parallel circuit= voltages the same on both branches= same current through driver with same voltage= same response).
Interesting about the amplifier not needing to put out much more power. I hadn't thought about it, but it makes sense.
Steve
I usually have to talk through these things, and then it becomes clear. As soon as I typed about the zobel being in parallel with the woofer, it all made sense (parallel circuit= voltages the same on both branches= same current through driver with same voltage= same response).
Interesting about the amplifier not needing to put out much more power. I hadn't thought about it, but it makes sense.
Steve
Tieftoener,
I appreciate the advice on the P17's, but I think I will stick with them for now. I will build something better in the future. No offense, and I appreciate your experience, but I might as well tweak the design I have for now. There's always another project, right? (I only have 3 more going right now, haha).
Steve
I appreciate the advice on the P17's, but I think I will stick with them for now. I will build something better in the future. No offense, and I appreciate your experience, but I might as well tweak the design I have for now. There's always another project, right? (I only have 3 more going right now, haha).
Steve
Good woofer/mid bass drivers
It is always a good idea to listen carefully to the woofer/midbass like the P17 installed in a cabinet with nothing else connected but the amp. It will sound dull compared to a regular wideband speaker. But listen to it for several hours , you will get used to it AND you will begin to see how it really sounds. Now change to some other driver and you will see the difference immediately. What you probably need to look at is how smooth the mids sound. Any raspiness or noisy vocal will tell you that the drive unit is not good enough. The HF extension is no indication of its performance in the mid band. The P17WH sounds very respectable compared to many other drivers in a test like this.
The P13WH is known very well for its flat midband response. In a test like this it has even less hf extension than the P17 ! So don't take that as any indication of the sound. Always listen to a driver without a crossover to see what you've got. Unfortunately tweeters will need some sort of LF cut off to protect it from dangerous lf excursion.
In my experience a harsh sounding speaker always leaves telltale marks even with a crossover installed. So be careful.
It is always a good idea to listen carefully to the woofer/midbass like the P17 installed in a cabinet with nothing else connected but the amp. It will sound dull compared to a regular wideband speaker. But listen to it for several hours , you will get used to it AND you will begin to see how it really sounds. Now change to some other driver and you will see the difference immediately. What you probably need to look at is how smooth the mids sound. Any raspiness or noisy vocal will tell you that the drive unit is not good enough. The HF extension is no indication of its performance in the mid band. The P17WH sounds very respectable compared to many other drivers in a test like this.
The P13WH is known very well for its flat midband response. In a test like this it has even less hf extension than the P17 ! So don't take that as any indication of the sound. Always listen to a driver without a crossover to see what you've got. Unfortunately tweeters will need some sort of LF cut off to protect it from dangerous lf excursion.
In my experience a harsh sounding speaker always leaves telltale marks even with a crossover installed. So be careful.
Fantastic:
No offense, but you obviously haven't experimented much with drivers. The P13WH WAS a great driver like 10 years ago. Cone technologies have changed... some things have gotten worse as a result of experimentation, and some things have gotten a lot better. Try comparing your P13 to the PL14... have you? I doubt it. Even Linkwitz himself states that the PL14 has LOWER distortion in ALL his tests. And he is (was?) one of the huge promoters for the P13. Personally, I never felt it stood up to the clout that others have given it over the past few years... in a lot of ways, I actually think that the P17 sounds a bit better in the mids - and in other ways, not so much.
The dispersion characteristics, total lack of detail and punch (not bass punch, but its dynamic capabilities) are just plain lacking compared to many other midrange drivers. How about the Morel MDM-55... now there's a beautiful midragne. Granted its a dome, but I'm just trying to relay that the midrange performance of the P13 is not what its cracked up to be. The Peerless 7" CSX, Vifa M18, Focal 4211, Scan Speak 8545 are all lightyears ahead of the P17 and P13. Depends on your budget, but the P13 is out in my book. The P17 has so much midrange distortion is crazy. Its a great driver for the price and very versatile for beginners, but there are just so many that outdo it nowadays.
Nobody special:
Don't sweat it man - tweak away!! Why rework one project when you could just have 5 different ones? Seriously, glad to see your acceptance. Good luck, and please keep us posted...
No offense, but you obviously haven't experimented much with drivers. The P13WH WAS a great driver like 10 years ago. Cone technologies have changed... some things have gotten worse as a result of experimentation, and some things have gotten a lot better. Try comparing your P13 to the PL14... have you? I doubt it. Even Linkwitz himself states that the PL14 has LOWER distortion in ALL his tests. And he is (was?) one of the huge promoters for the P13. Personally, I never felt it stood up to the clout that others have given it over the past few years... in a lot of ways, I actually think that the P17 sounds a bit better in the mids - and in other ways, not so much.
The dispersion characteristics, total lack of detail and punch (not bass punch, but its dynamic capabilities) are just plain lacking compared to many other midrange drivers. How about the Morel MDM-55... now there's a beautiful midragne. Granted its a dome, but I'm just trying to relay that the midrange performance of the P13 is not what its cracked up to be. The Peerless 7" CSX, Vifa M18, Focal 4211, Scan Speak 8545 are all lightyears ahead of the P17 and P13. Depends on your budget, but the P13 is out in my book. The P17 has so much midrange distortion is crazy. Its a great driver for the price and very versatile for beginners, but there are just so many that outdo it nowadays.
Nobody special:
Don't sweat it man - tweak away!!
Why rework one project when you could just have 5 different ones? Seriously, glad to see your acceptance. Good luck, and please keep us posted...
from what i remember the P13s have a high loss surround while some (if not all) of the drivers it is being compared to have low loss surrounds. does this have to do with the difference in the sound of the P13 v/s the M13, 8545, PL14, M18, CSX, etc...
again i can be totally wrong but i think the P13 was from an era when a flat frequency response was the touted as a USP. Today other factors are being introduced (Acceleration factor (Bl/Mms) , Cms, etc..) and being sold as USPs.
Also I feel with some of the more exotic cone materials (carbon, kevlar, metals (Mg, Al, etc), glass etc..) driver manufacturers are using low loss surrounds to damp the drivers. I remember one manfacturer who actaully hinted at this (verbally in person off teh record) about 10 years ago. I am not saying that this (a low loss surround) is bad but just that it is the development of drivers today. The SS revelator series, CSX series, SEAS Excel series etc represents close to teh sate of the art in drivers today and all these drivers are quite good (given their design parameters).
For example Ted Jordan's wonderful 50mm driver of the 70s had some ringing problems. I would love to be correctd on this but I am inclined to believe that the 21st century versions (or even the 90s versions) used low loss surrounds to reduce the problems of ringing.
Am I barking up the wrong tree? Any driver manufacturers who can shed some light on this out there?
again i can be totally wrong but i think the P13 was from an era when a flat frequency response was the touted as a USP. Today other factors are being introduced (Acceleration factor (Bl/Mms) , Cms, etc..) and being sold as USPs.
Also I feel with some of the more exotic cone materials (carbon, kevlar, metals (Mg, Al, etc), glass etc..) driver manufacturers are using low loss surrounds to damp the drivers. I remember one manfacturer who actaully hinted at this (verbally in person off teh record) about 10 years ago. I am not saying that this (a low loss surround) is bad but just that it is the development of drivers today. The SS revelator series, CSX series, SEAS Excel series etc represents close to teh sate of the art in drivers today and all these drivers are quite good (given their design parameters).
For example Ted Jordan's wonderful 50mm driver of the 70s had some ringing problems. I would love to be correctd on this but I am inclined to believe that the 21st century versions (or even the 90s versions) used low loss surrounds to reduce the problems of ringing.
Am I barking up the wrong tree? Any driver manufacturers who can shed some light on this out there?
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