Peak in power response or dip in directivity, right?
But I guess everyone knows what you mean ...
Listening distance and room acoustic is likely the single biggest reason why anyone may prefer minimizing the distance between drivers or not. In a very nearfield listening situation or one where the early reflections are significantly reduced, closing the CTC distance may be the preferred option. Coaxial speakers do very well in nearfield listening. Making the central lobe wider and flooding the nearfield area will help even more with supression of off axis sound in what is perceived. The fact that the measured DI suffers won't have any negative consequence on what is heard, but if reviewed at ASR your speaker will be labelled with a directivity error. Holes in the power response are hardly audible at all but peaks are, Lipshitz and Vanderkooy found that a long time ago. I wouldn't worry about the power dip in Jim's Textreme but I would do something with the baffle to reduce the tendency of the off axis to rise in the 3 to 4 K region as this can make some music sound unbearable.
The 1.2 wavelength spacing in most practical cone and dome speaker designs creates small holes in the vertical response either side of the 0 degree axis, this is not likely to cause any issue in 2m plus listening situations but it will make the speaker more universal as Jim said. For anyone who doesn't like the looks of a big gap and I am one of them, use a higher crossover frequency if the drivers allow.
As dcibel said it's just important to avoid the old rule of thumb, that putting the drivers as close as possible is always best, because for most designs and most use cases it is not.
augerpro
You have taken a leap off the deep end.
The conversation was about speaker measurements. See Directivity Vertical and Horizontal, even polar plots. There are no room reflections noted.
Speaker measurements are best made in an anechoic space or with methods and software tools to remove the influence of any reflections.
hifijim tells us that his design goal is smooth continuous directivity plots both on and off axis without any discontinuities. Such a speaker will sound its' best in any room.
Room reflections should be chapter 2.
One layer of complexity at a time.
DT
Last edited:
No he has just tried to explain the why. All CTA2034 measurements are intended to be anechoic or quasi anechoic. The "early reflections" curve is created by averaging a specific set of those anechoic measurements together. Just the same as the "listening window" response is created by averaging a different group of the measurements.
The choice of angles and the name "early reflections curve" came from some research by Alan Devantier at Harman. It is meant to be representative of the first reflections in a hypothetically standard room. Of course it won't represent any specific room but is in the ball park for many. It is this curve and the DI where the differences in changing the vertical distance between drivers can be seen in a CTA2034 plot.
A lot of the terms come from Harman as they created the Spinorama for themselves before it was turned into a standard. Anyone who is not familiar with the Harman research and the terms they used could be confused as they are very similar to commonly used expressions.
No reflections were actually used 🙂
I am starting to repeat myself, so see previous posts.
I just don't agree with the idea, since it solely assumes it's important to begin with, without proper foundation.
So therefore we can't make such claims either.
From a practical stand point, it's also not as easy to just tell people to move them apart. Again see previous posts where this has been explained.
Last edited:
The whole point is that in a speaker design you constantly have to make decisions that includes everything at once.
But maybe that's not what you mean?
There is the other variable as well, crossover frequency fluid mentioned, drivers could be rather conventionally positioned, but xo bit higher, this also affects sound and the graphs, also distortion. c-c together with xo frequency allows jugling for best sound, what ever that is for each speaker and drivers.
yeah... I thought @augerpro did an excellent job explaining succinctly how the CTA2034A calculations work. No deep end here.
Yes - I discussed this in post #74, although I might have been too verbose...
https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7701644
As I showed in my table, if a 5 inch (125 mm) driver is crossed to a typical 105 mm flange tweeter at 3.4k, the spacing to achieve 1.2xWL is 0 ... i.e, the drivers are touching.
I have always had difficulty with crossover frequencies this high. No matter what baffle shape I try, I can't get a good DI response. Anytime I use a 5" driver and a 1" tweeter, the best DI response comes from an Fc in the 1.8k - 2.2k range.
Hifijim, it would worth mentioning if it was on flat or tilted/stepped baffle. That makes difference.
Symetric LR2 allowes higher crossovers easily and has good DI end power response.
Symetric LR2 allowes higher crossovers easily and has good DI end power response.
Yes I should elaborate a bit. I said
... And that is with a flat non-tilted baffle. In the case of the 2x8+5+1 tower speaker, I was using DSP, so I could control the delay/timing of the mid and tweeter. An Fc of 2k worked out best in that case to optimize the DI curve. I listened to both LR2, LR4, and quasi-LR3. I thought LR2 and LR4 sounded best... There was a slight difference but I could not decide which one was superior, they were just subtly different. In the end, I was concerned that a 2nd order slope at 2k was not enough protection for the tweeter. Perhaps I was overly cautious.
In the other speaker, I also used a flat baffle, but the crossover between the mid and tweeter was a passive network. Given the natural rolloff of the tweeter, I don't think I could have achieved an acoustic LR2 slope. I tried to simulate it and the network became complicated. A fairly simple network on the mid and tweeter brought about an acoustic LR4. As I am sure you have experienced, driver responses oftentimes "force our hand" when designing passive networks.
j.
15W/4434G => mentions alu ring in magnet
15M/4624G => Was tested by another user here on forum and users was not too impressed. Bump at impedance looks like it would benefit from edge coating.
15W/4424G00 => mentions NO alu ring in magnet in specs. Think that one looks most promising of the lot. In EU about half price of SB15.
Admit SB15 Alu with Purify series passive notch looks very nice. Another user also documented nice improvement from adding strong NEO magnet.
Another maybe candidate for good midrange is: Tymphany FSL-0512R01-08:
Some believe same midrange as the one used in Kii Audio Three.
https://www.soundimports.eu/en/peer...nJM1cGUPL3xy5juA6ieYztmZxJjTxmVRoCC9oQAvD_BwE
I have 3 on the shelf. I will try mount one and do a full spin. Then I will try dampening with glue/felt dots. I think it is perfect candidate for nice shallow LR12 filters.
The issue with most Scan Speaker woofers is the surround.
They seem to be very focused to get everything done with one woofer.
Even for some smaller 5 inch woofers.
It beats me why they don't use edge coating on their entire range.
But the answer could be so simple as that most people and companies just don't really care.
SB Acoustics NBAC, CAC and NRX2 is miles better than many Scan Speaker mids btw.
Based on measurement data.
They seem to be very focused to get everything done with one woofer.
Even for some smaller 5 inch woofers.
It beats me why they don't use edge coating on their entire range.
But the answer could be so simple as that most people and companies just don't really care.
SB Acoustics NBAC, CAC and NRX2 is miles better than many Scan Speaker mids btw.
Based on measurement data.
b_force: "based on measurement data" - I can agree with that.
I have worked and made the projects with many Scan Speak, Satori, SB etc drivers. All of them have models that suffer from cone edge resonance a lot (SB17 with NBAC and CAC as exceptions, Satori MW Papyrus cones) - they all have clear FR wiggle + associated distortion peaks, then models with milder symptoms of the resonance - mild FR irregullarities though distortion is ok, and models with excellent behavior in 1000-2000Hz area.
I know SB17CAC, NBAC and MFC very well and I heard not only my project but also others and also commercial, and yet those midwoofers are perfect on the paper, they lack a lot in sound quality (midwoofer in 2way). So I really hope SB15xxx is totally different animal (well, I actually doubt).
ScanSpeak and other brands know what they do really well. Not all drivers they do are perfect on the paper, but they actually sound good. Discovery 15W has also almost no signs of cone edge resonances, 18W Discovery as well. The way the driver sound is the sum of many things and drivers properties, Alu cone and perfect distortion (I mean standard H2-H3-H4-H5) are just a parts of much complex equation.
One example for all, U18RNX, generally not perfect in any aspect, but it offers good balance of all aspects, and having the comparison with SB17 and many other drivers, I would pick U18 over SB17 anytime.
So, I do not mean to argue about measured performance. I just want to offer another point of view and experiences, and to suggest that too much focus on measured performance might be misleading.
I have worked and made the projects with many Scan Speak, Satori, SB etc drivers. All of them have models that suffer from cone edge resonance a lot (SB17 with NBAC and CAC as exceptions, Satori MW Papyrus cones) - they all have clear FR wiggle + associated distortion peaks, then models with milder symptoms of the resonance - mild FR irregullarities though distortion is ok, and models with excellent behavior in 1000-2000Hz area.
I know SB17CAC, NBAC and MFC very well and I heard not only my project but also others and also commercial, and yet those midwoofers are perfect on the paper, they lack a lot in sound quality (midwoofer in 2way). So I really hope SB15xxx is totally different animal (well, I actually doubt).
ScanSpeak and other brands know what they do really well. Not all drivers they do are perfect on the paper, but they actually sound good. Discovery 15W has also almost no signs of cone edge resonances, 18W Discovery as well. The way the driver sound is the sum of many things and drivers properties, Alu cone and perfect distortion (I mean standard H2-H3-H4-H5) are just a parts of much complex equation.
One example for all, U18RNX, generally not perfect in any aspect, but it offers good balance of all aspects, and having the comparison with SB17 and many other drivers, I would pick U18 over SB17 anytime.
So, I do not mean to argue about measured performance. I just want to offer another point of view and experiences, and to suggest that too much focus on measured performance might be misleading.
Last edited:
I have rarely seen a driver that measures well and sounds horrible.
Otherwise you simple haven't done enough or not the right kind of measurements.
But it makes very little sense in general.
Meh, don't really agree with this.
They used to have a good formula 20-30 years ago and now just stick to it.
But I don't find their prices that competitive anymore, also from a professional point of view.
This is even more true for Seas.
They aren't bad at all, but their price/performance ratio isn't good anymore these days.
I much rather advice SB Acoustics, Wavecor, or Purifi and Kartesian on the other side.
For DIY'ers, Dayton is quite interesting as well especially in North America.
Not horrible, just not acceptable for me. Based on experiences with the sound of other drivers.
Buchardt S400, not my project, SB17NBAC, one of the examples of typical SB17 sound. I know some owners, and they admitted my assessment of SB17 sound was correct.
Wavecor, Kartesian, Purifi, yes. SB and Satori yes, just not everything.
You do not share any details nor sound descriptions of your projects, yet you are quite dismissive to my opinions, and judging from other thread, not just mine. Do you have any experience with SB17? I admit SB15 might be different.
Buchardt S400, not my project, SB17NBAC, one of the examples of typical SB17 sound. I know some owners, and they admitted my assessment of SB17 sound was correct.
Wavecor, Kartesian, Purifi, yes. SB and Satori yes, just not everything.
You do not share any details nor sound descriptions of your projects, yet you are quite dismissive to my opinions, and judging from other thread, not just mine. Do you have any experience with SB17? I admit SB15 might be different.
Because as soon as there is little distortion left, there is no other sound.
The implementation, system design and crossovers could be totally wrong or less optimal.
I agree that the Buchardt S400 is a less optimal design, it's also not my thing.
But don't blame the drivers for that.
I think Erin did a review on that one as well?
I have used the SB17 and SB15 (variants) a whole lot, even in double blind tests with other woofers.
They have by far one of the best price/performance ratios.
As soon the overal system is similar or the same, I can't hear any difference anymore.
Or if there are noticeable differences, they can be clearly pointed out from the measurements why.
For this reason I don't think sound descriptions are useful at all.
So much depends on context.
I am literally never interested in them.
Mostly because many people also put judgements, descriptions and blames on the wrong things.
Comparing apples with potatoes, yet blaming the driver for it.
If a driver shows good objective data, we can make a good performing loudspeakers with it
That's all I care about.
I don't know what you mean with dismissive, I give my opinions so do other people?
The fact that people read all kinds of things into that is not my problem to be perfectly honest.
We all have our way of communicating, the vast majority is misreading, miscommunication, difference in culture and upbringing.
Something many people don't seem to realize.
Even more so how much harder that is on just written text on forums.
I can guarantee that there are plenty of people who find other things extremely dismissive.
They just don't feel the need to mix that into a conversation about loudspeakers or other tech stuff.
Just stick to the subject and respect people for who they are, there is absolutely no reason to get personal with these kinds of subjects.
Maybe just simply ask what someone means by something instead of judging?
Thanks for more elaborate response, I appreciate it. This is the kind of the response I understand and respect.
We do not have to agree on everything, it is fully ok.
My experiences come from passive systems, so I am more interested what driver can do in passive loudspeaker. In passives it is nearly impossible to massage two drivers to have the same response for the fair comparison, so if I spend a year making multiple itterations and trying basically everything, and I still hear I do not like the sound of the driver, I try another one, and it is ok, then I am not interested in the first driver anymore. If I hear another designs and commercial products with that driver and I recognize the same issue then I am not interested in that driver even more.
Anyway, this is off topic, not the direction I meant.
We do not have to agree on everything, it is fully ok.
My experiences come from passive systems, so I am more interested what driver can do in passive loudspeaker. In passives it is nearly impossible to massage two drivers to have the same response for the fair comparison, so if I spend a year making multiple itterations and trying basically everything, and I still hear I do not like the sound of the driver, I try another one, and it is ok, then I am not interested in the first driver anymore. If I hear another designs and commercial products with that driver and I recognize the same issue then I am not interested in that driver even more.
Anyway, this is off topic, not the direction I meant.
I seriously consider the subjective assessments that people make of speakers. We don't always know why something sounds the way it does, or what physical mechanism is responsible, but that does not mean the perception is not a real perception.
Of course we must always be aware that biases can skew our perceptions. I have found that skewed perceptions due to bias or preconceived expectations tend to disappear over the long term, as the truth of the situation pushes out the falseness of the bias.
I believe that 95% of speaker sound quality is frequency response and sound radiation pattern. Getting that part right is the first and most important job in speaker design. Any speaker which gets this part right is going to sound very good, even if it has other defects. Once this part has been handled well, other things start to become important. There are a lot of interconnected factors which must be balanced and optimized to get that last 5%, and it is a difficult task because whatever we do, we must not affect the frequency response and sound radiation pattern that we worked so hard to optimize in the first place.
@PKAudio - I appreciate your honest assessment of SB drivers. I am well aware of your general lack of enthusiasm for SB woofers and midbass drivers. Whatever quality you are hearing with these drivers, I am not perceiving it. But I do not doubt that you are hearing something real.
Of course we must always be aware that biases can skew our perceptions. I have found that skewed perceptions due to bias or preconceived expectations tend to disappear over the long term, as the truth of the situation pushes out the falseness of the bias.
I believe that 95% of speaker sound quality is frequency response and sound radiation pattern. Getting that part right is the first and most important job in speaker design. Any speaker which gets this part right is going to sound very good, even if it has other defects. Once this part has been handled well, other things start to become important. There are a lot of interconnected factors which must be balanced and optimized to get that last 5%, and it is a difficult task because whatever we do, we must not affect the frequency response and sound radiation pattern that we worked so hard to optimize in the first place.
@PKAudio - I appreciate your honest assessment of SB drivers. I am well aware of your general lack of enthusiasm for SB woofers and midbass drivers. Whatever quality you are hearing with these drivers, I am not perceiving it. But I do not doubt that you are hearing something real.