The reason to like the high Z versions of drivers, could it be because they have higher Le, so they are not not producing af much high frequencys. And so they seems more smooth and less screaming!
Those older 32ohm drivers refered to earlyer in this posts, are they limited in frequency responce or are they reaching 15-20KHz like the drivers today? Please comment on what are good older drivers? Electro Voice or...?
Those older 32ohm drivers refered to earlyer in this posts, are they limited in frequency responce or are they reaching 15-20KHz like the drivers today? Please comment on what are good older drivers? Electro Voice or...?
Hi,
Le should be seen in relation to Re, t=L/R.
Therefore, hf response should be about the same regardless Z.
Le should be seen in relation to Re, t=L/R.
Therefore, hf response should be about the same regardless Z.
sumaudioguy: Please take a chill pill. 😀 You seem to think that folks here are disregarding your experience and tests. That is not the case. We are quite interested what you have found.
The problem with a forum like this is that a lot of opinions get presented without anything to back them up. Opinions are fine, as long as they are stated as such. It's difficult in the clutter of 1000s of posts to know what is what and who is who. To know what is opinion and what has real research behind it. That is why presenting good measurements and tests goes such a long way here. Simply saying "I've done the tests" is good, but showing us the data is much, much better. That way we know that it is not just opinion and is based on careful study.
Unfortunately, all you have done is tell us about your lab testing, without actually showing any of it, or telling where and how it was done. So you may understand why some readers here take this as opinion. I hope you understand that when a new member comes in with strong statements right off the bat, the older members are cautious. There is a lot of history behind that.
Around here a thick skin is needed if you wish to make bold statements. You'll have to be prepared to back them up because you will be challenged, no matter what they are. That's true for everyone here.
The problem with a forum like this is that a lot of opinions get presented without anything to back them up. Opinions are fine, as long as they are stated as such. It's difficult in the clutter of 1000s of posts to know what is what and who is who. To know what is opinion and what has real research behind it. That is why presenting good measurements and tests goes such a long way here. Simply saying "I've done the tests" is good, but showing us the data is much, much better. That way we know that it is not just opinion and is based on careful study.
Unfortunately, all you have done is tell us about your lab testing, without actually showing any of it, or telling where and how it was done. So you may understand why some readers here take this as opinion. I hope you understand that when a new member comes in with strong statements right off the bat, the older members are cautious. There is a lot of history behind that.
Around here a thick skin is needed if you wish to make bold statements. You'll have to be prepared to back them up because you will be challenged, no matter what they are. That's true for everyone here.
Fine for me if it is higher Le that sounds better, but we dont know. maybe some one can describe in more details how these older types of compression drivers are build. New is certainly not always better.
- A compressiondriver have a strange meassured impedance, what is the Fs for the driver on suce a curve. In general it has two impedance peaks, i guess it is because it has kind of a chamber behind and infront of the cone. When manufactures show these impedance curvs, how are they meassured, on a horn or...?
- A compressiondriver have a strange meassured impedance, what is the Fs for the driver on suce a curve. In general it has two impedance peaks, i guess it is because it has kind of a chamber behind and infront of the cone. When manufactures show these impedance curvs, how are they meassured, on a horn or...?
Yes, they are usually measure on a horn, or on a tube. (it should be stated)
So you are seeing both the horn and the driver in the impedance plot. In much the same way you will see the woofer and the box in the plot of a bass reflex system.
So you are seeing both the horn and the driver in the impedance plot. In much the same way you will see the woofer and the box in the plot of a bass reflex system.
Never was a less accurate statement made. So you are saying that if it "sounds better" to you, that you can speak for everyone else and say that "it is better"? That's either incredibly arrogant or incredibly nieve.
That is what Im trying to figure out.
How does the response differ between 8 ohm and 16 ohms.
I would order 16 Ohm CDs if this is truely the case.
Hi,
For example, if we connect two tweeters in series the amp does see 2xRe and 2xLe but no different frequency response due to what I wrote earlier.
The same thing should hold true between a single 8Ohm and 16Ohm driver (everything else being equal).
For example, if we connect two tweeters in series the amp does see 2xRe and 2xLe but no different frequency response due to what I wrote earlier.
The same thing should hold true between a single 8Ohm and 16Ohm driver (everything else being equal).
Well the only difference is the dB level for 1 Watt of power, correct?
Could it just be another audiophile type mistake in thinking dB difference equates to "sounds better".
As I said before, I didn't measure or detect any differences between 8 ohm and 16 ohm drivers from B&C.
Fact or Friction
First off it is my private lab and I want to keep it that way and are you panamaniac calling me a liar? What is your cred in study of drivers and the details of there working in the lab and in practice?
Second-
_____ Φ²S²
Ra = ---------- * (.0005610)
______Re m²
note: the underlines are place holders because of the auto format on this forum so please ignore them.
Asymptotic efficiency is equal the Bl squared times S squared over Re times m squared times that constant where Φ = Bl , S = area , Re =dc resistance , and m = moving mass.
Now look at this formula and you will see winding a voice coil the same length and number of layers decreases m and increases Φ and Re. So there are 3 factors which increase efficiency and 1 which decrease efficiency. So what happens with a higher Z voice coil? At this point it should be fairly obvious, comparing a 16 and 8 ohm otherwise identical driver, efficiency would increase unless the manufacturer adds mass or changes the voice coil spec. Tesla early realized small wire and higher drive voltage works far better than big wire and higher driver current. Usually, by those who believe the specs should match, what is done is to either make the voice coil longer or add mass until the 16 ohm matches the 8 ohm version . This is usually not done on horn drivers but is done with woofers and midrange. So the driver in higher Z is more efficient.
Third-
____2 pi Fs m
Q= ----------------
This shows us with the same thoughts that Q will be lower with a higher Z coil.
With these things in mind keeping everything else the same such as the magnet and diaphragm the 16 ohm voice coil will always be better than the 8 ohm voice coil because it will have lower Q and higher efficiency. Both a plus. Further if the magnet top plate and pole piece structure are optimized for the higher Z coil a big win occurs because the gap can be thinner increasing flux density and really improving the driver. These old 32 ohm drivers I mentioned were optimized for the very thin voice coil so the absolutely blew away the 8 ohm version in loudness, distortion, and linearity in all domains.
For some of these other post the inductance of the voice coil is not even in the response formula so that is not an issue.
Looking at compression drivers and their frequency response is similar to determining how fast a car will go by the speed rating of the installed tires. The BIGGEST question for any transducer is what is the time, frequency, and energy envelope where these parameters stay within one slope? To that end I have yet to see a compression driver of any magnitude, usable to 110dBa, that will keep it together for more than a decade. Yes many will produce noise up to 20kHz and higher but the useful end is seldom above 15kHz or below 1500Hz for anything available today as a horn intended to be used for the highs. It is certainly possible to make a horn go higher but then the bottom end of the response also goes higher and the decade limit still applies. Raliegh discuss this very situation in some of his original work which has been used to define horns since that long time ago, about 100 years. Has anyone here read that landmark work?
As for panamaniac, personally I see you as the great questioner and protector who knows little, does not carefully read post, and throws out doubt on everything presented by anyone. As many say many have a lot to offer however this protectorate behavior is shown in a lot of the post you have made on these forums. I would suggest you read the post much more carefully and take the time to follow provided links to review information presented so your statements and questions are meaningful instead of just obstructions to progress and learning.
Know what is really difficult? To write a formula on this forum with the auto formatting!
First off it is my private lab and I want to keep it that way and are you panamaniac calling me a liar? What is your cred in study of drivers and the details of there working in the lab and in practice?
Second-
_____ Φ²S²
Ra = ---------- * (.0005610)
______Re m²
note: the underlines are place holders because of the auto format on this forum so please ignore them.
Asymptotic efficiency is equal the Bl squared times S squared over Re times m squared times that constant where Φ = Bl , S = area , Re =dc resistance , and m = moving mass.
Now look at this formula and you will see winding a voice coil the same length and number of layers decreases m and increases Φ and Re. So there are 3 factors which increase efficiency and 1 which decrease efficiency. So what happens with a higher Z voice coil? At this point it should be fairly obvious, comparing a 16 and 8 ohm otherwise identical driver, efficiency would increase unless the manufacturer adds mass or changes the voice coil spec. Tesla early realized small wire and higher drive voltage works far better than big wire and higher driver current. Usually, by those who believe the specs should match, what is done is to either make the voice coil longer or add mass until the 16 ohm matches the 8 ohm version . This is usually not done on horn drivers but is done with woofers and midrange. So the driver in higher Z is more efficient.
Third-
____2 pi Fs m
Q= ----------------
____Rm + Φ²/Re
This shows us with the same thoughts that Q will be lower with a higher Z coil.
With these things in mind keeping everything else the same such as the magnet and diaphragm the 16 ohm voice coil will always be better than the 8 ohm voice coil because it will have lower Q and higher efficiency. Both a plus. Further if the magnet top plate and pole piece structure are optimized for the higher Z coil a big win occurs because the gap can be thinner increasing flux density and really improving the driver. These old 32 ohm drivers I mentioned were optimized for the very thin voice coil so the absolutely blew away the 8 ohm version in loudness, distortion, and linearity in all domains.
For some of these other post the inductance of the voice coil is not even in the response formula so that is not an issue.
Looking at compression drivers and their frequency response is similar to determining how fast a car will go by the speed rating of the installed tires. The BIGGEST question for any transducer is what is the time, frequency, and energy envelope where these parameters stay within one slope? To that end I have yet to see a compression driver of any magnitude, usable to 110dBa, that will keep it together for more than a decade. Yes many will produce noise up to 20kHz and higher but the useful end is seldom above 15kHz or below 1500Hz for anything available today as a horn intended to be used for the highs. It is certainly possible to make a horn go higher but then the bottom end of the response also goes higher and the decade limit still applies. Raliegh discuss this very situation in some of his original work which has been used to define horns since that long time ago, about 100 years. Has anyone here read that landmark work?
As for panamaniac, personally I see you as the great questioner and protector who knows little, does not carefully read post, and throws out doubt on everything presented by anyone. As many say many have a lot to offer however this protectorate behavior is shown in a lot of the post you have made on these forums. I would suggest you read the post much more carefully and take the time to follow provided links to review information presented so your statements and questions are meaningful instead of just obstructions to progress and learning.
Know what is really difficult? To write a formula on this forum with the auto formatting!
It can be shown that the efficiency of a motor depends only on the BL and the amount of copper in the gap. How this copper is arranged does not matter. It does matter a little if all the copper is not all in the gap, but this is second order effect, especially for compression drivers.
Remember here that we are talking about efficiency - which is a power transfer. It is different if you are talking about voltage sensitivity.
And no I am not going to prove that, look it up.
Remember here that we are talking about efficiency - which is a power transfer. It is different if you are talking about voltage sensitivity.
And no I am not going to prove that, look it up.
Obviously moderators need to have thick skin too 🙄
I have 4 cheap Foster supertweeters
They sound awful
Beats me why, but they do sound quite sweet coupled in series pairs
Its not subtle or hard to hear the difference
Could be due to better powerhandling at lower frequency
Tho, couple in paralel they still sound awful
Only the series connecting have the positive effect
But doubtfully a general rule
That formula is for efficiency of a transducer and not simply the motor. It is not voltage sensitivity. It is watt. So you do not need to look up any formula as this is correct. These are all the factors which affect efficiency of a transducer.
So I can wind with a 10ga wire in a big gap and wind with a 30 ga wire in a small gap and if the flux is the same the motor will produce the same force for a given current but the heavy wire one will weigh 1000 times more and produce the same force. Making the motor 1000 times heavier does not effect its efficiency? I think you need to re-examine that thought as clearly something is left out.
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That is all nice but they say a picture is worth a 1000 words 😀
How about some plots showing the differences?
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