I would normally say use what works for that project. There really aren't too many absolutes that I know of. Each design is different.
But you'd never come to any conclusions at all, if you adopted the different horses for courses approach! 😀
This is actually a beautiful speaker on third order (negative polarity, because 8" bass is badly time aligned at 3.5kHz) filters:
Reflex Sony E44 with a good crossover. Mylar "balanced drive" cone tweeter with good dispersion and Eminence style cloth surround bass with transparent (or non-existent) dustcap. It sounded terrible with a soft dome. It also sounded terrible on a single cap crossover. I think I might up the 1mH bass coil though.
This one was pretty good too, but the Visaton TW70 has some issues at the very top around 15kHz IMO:
They should lose the paper dustcap IMO. A phase plug would be better.
This is the Visaton DT94 mylar tweeter. Very smooth too:
But overall, I like the Monacor HT22/8 best. Incredible for a £6 tweeter. 😀
This is actually a beautiful speaker on third order (negative polarity, because 8" bass is badly time aligned at 3.5kHz) filters:
An externally hosted image should be here but it was not working when we last tested it.
Reflex Sony E44 with a good crossover. Mylar "balanced drive" cone tweeter with good dispersion and Eminence style cloth surround bass with transparent (or non-existent) dustcap. It sounded terrible with a soft dome. It also sounded terrible on a single cap crossover. I think I might up the 1mH bass coil though.
This one was pretty good too, but the Visaton TW70 has some issues at the very top around 15kHz IMO:
An externally hosted image should be here but it was not working when we last tested it.
They should lose the paper dustcap IMO. A phase plug would be better.
This is the Visaton DT94 mylar tweeter. Very smooth too:
An externally hosted image should be here but it was not working when we last tested it.
But overall, I like the Monacor HT22/8 best. Incredible for a £6 tweeter. 😀
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Must be 40mV and 48mV OR 0.04V/0,048V otherwise there is NO bias at all.
Anyway the difference in a number group is just 20%, typical for production
spread and warmup, remember the resistors where said voltage is dropped
have typically 10% tolerance...
I just looked it up in the manual, it was 4mV for the Rotel RA-931 actually. 🙂
Whatever, I got it right in the end, and it sounded a heck of a lot better. But appreciate your paying attention. Always the sign of a creative mind. 😎
But Lojzek, I could not sell or give you a soft dome with a clear conscience. They are HORRIBLE! 😀
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This is ununsually low, part of the answer is it is checked across a single
emitter resistor only, 4mV correspond to about 20 mA in each output transistor.
Well, there is only one option available, horrible tweeters
can't be sold, only given as a gift
. Take care.
Try the cone tweeters, Lojzek!
In an ideal world we'd be dealing with Class A amplifiers. But they do run kinda HOT. Terrible compromises in audio. What can you do? I once built a near pure current transistor amplifier which is called a transconductance amplifier in modern amplifier speak, but it tended to overheat. Not practical at all. Back to the drawing board. I think John Linsley Hood did it best. 🙂
I don't give amplifiers much thought these days. It's not my current business. But the 4mV is across two 0.22R emitter resistors for sure on the RA-931 Class AB schematic. Barely turned on, I suppose.
In an ideal world we'd be dealing with Class A amplifiers. But they do run kinda HOT. Terrible compromises in audio. What can you do? I once built a near pure current transistor amplifier which is called a transconductance amplifier in modern amplifier speak, but it tended to overheat. Not practical at all. Back to the drawing board. I think John Linsley Hood did it best. 🙂
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Saw in the diagram it was 4mV across one resistor.
JLHs original schematic and its modern successors are worth a try.
http://6moons.com/industryfeatures/zen/plh.pdf
https://www.passdiy.com/project/amplifiers/the-plh-amplifier
Flippin heck, as_audio, you are quite right again. 😱
The test point of 4mV is across a single 0.22R resistor on rechecking the schematic. Nevertheless, I couldn't really miss the two prongs on the circuit board on the test point. 🙂
Like I say, amps ain't my business these days. I just trust Rotel to get it right. 😎
The test point of 4mV is across a single 0.22R resistor on rechecking the schematic. Nevertheless, I couldn't really miss the two prongs on the circuit board on the test point. 🙂
Like I say, amps ain't my business these days. I just trust Rotel to get it right. 😎
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I've just given you the justification more clearly than in any other post I've ever seen on the subject. It's all in the phase plot. You do know what a phase plot represents, don't you? 🙂
Perhaps not. You'd rather flame than think it seems.
Let's not get into this again. I thought we went over this before in that other thread. A loudspeaker is a minimum phase device and as such the phase follows what the frequency response does. In other words if the phase tracking is poor, or has kinks in it, you can sort this out via the filter. This doesn't mean a soft dome is broken if another driver happens to track better. You should easily be able to make the soft dome track just as well with some filter jiggery pokery. Maybe this complicates the design for the soft dome, but it doesn't mean it's bad.
You really haven't.
All drivers go through breakup at some point. Soft domes do this in the last couple of octaves, we know this, but it's done in a controlled way and it actually helps to improve the off axis response. This doesn't make it sound like mush.
There is nothing remarkable about it. The only remarkable thing about the XT25 is that, when placed on a large flat baffle and flush mounted, it has a very flat frequency response. This isn't because it's a ring radiator it's because it's a well designed tweeter.
Group delay is an intrinsic part of any filter response, be it how a driver behaves without a crossover, or how just the crossover behaves on its own. If there's a kink in the frequency response there's a kink in the phase and kink in the group delay. Equalise the kink in the FR away and the others go away too.
If you've got a flat axial frequency response from two well integrated drivers then the CSD will be clean. The group delay will show nothing other than what you'd expect for the filter type integrating the drivers and the phase tracking will be excellent if the filters are suitable. If the distortion is also appreciably low then the soft dome tweeter will not have lost any linearity.
By definition linear distortion is very low as the frequency response is flat and if non linear distortion is also very low, then the other evil is low too. Linearity in place? Check.
The D2608 is actually has a 26mm diameter coil.
No, but on the flip side this doesn't mean you should also ignore frequency response linearity. It might be necessary in some instances to go with a more wonky response, but this is usually only necessary if the drivers are poorly matched.
5th element, you are one of the brighter guys at DIY Audio, and you're still missing the best ideas in the current physics.
Lecture 1 | Topics in String Theory - YouTube
Professor Leonard Susskind of Stanford University has previously explained why waves on a sphere, like a soft dome or a dustcap, don't really work. I've lost the exact reference in M-theory, although I went through it before, but that is your problem rather than mine. 😀
This stuff is tremendously hard, but it has relevance to the whole loudspeaker problem at some very fundamental level. Like most competent physicists, he will take on most questions.
Susskind is, IMO, the best physicist of the 21st. century. Better than Einstein. Pure brilliance. Enjoy. 🙂
Lecture 1 | Topics in String Theory - YouTube
Professor Leonard Susskind of Stanford University has previously explained why waves on a sphere, like a soft dome or a dustcap, don't really work. I've lost the exact reference in M-theory, although I went through it before, but that is your problem rather than mine. 😀
This stuff is tremendously hard, but it has relevance to the whole loudspeaker problem at some very fundamental level. Like most competent physicists, he will take on most questions.
An externally hosted image should be here but it was not working when we last tested it.
Susskind is, IMO, the best physicist of the 21st. century. Better than Einstein. Pure brilliance. Enjoy. 🙂
How a dome tweeter breaks up has nothing to do with it imo, all drivers break up in different ways but this is seen in the measurements. Of course you need a comprehensive set of on axis, off axis and distortion measurements to see if anything untoward is going on, but usually there isn't. If the frequency response is flat (or gently falling) and the distortion is low, how is the tweeter mush? It's reproducing the signal input to it accurately.
If there were something to dome tweeters going to 'mush' above a certain frequency, due to their breakup, then using a suitable metal dome should cure all of them. Good metal domes don't break up at all until significantly above the audible spectrum. The only issue is that this creates are a series of products in the non linear distortion products that are so high that we cannot hear them, but they can create some low level IMD products that we can hear, but if the tweeters motor is any good, which lots are, they are below audibility.
If there were something to dome tweeters going to 'mush' above a certain frequency, due to their breakup, then using a suitable metal dome should cure all of them. Good metal domes don't break up at all until significantly above the audible spectrum. The only issue is that this creates are a series of products in the non linear distortion products that are so high that we cannot hear them, but they can create some low level IMD products that we can hear, but if the tweeters motor is any good, which lots are, they are below audibility.
Waves on a sphere don't work...huh? Is our planet not a sphere on which waves of all sorts are working all the time? Or are you just being smarter than everybody, again? We actually need news we can use around here
System7...thanks for hijacking this post. I actually REALLY appreciated your input, until it became a lecture about how "Clausen discovered how bad domes sound...etc etc..., and the science has proven, blah blah" and you didn't actually bother to read what I posted or comment on what I stated I hear. I.E. "the LCR has made a night and day difference." But no, I don't actually hear that...even though I DO!
One thing I know for a FACT...science is NEVER PROVEN! There always theories! Theories which are eventually proven wrong.
I don't care what your graphs "show". They should be used as a guide and tweaked by ear, as the post Pascal posted about this tweeter, and I couldn't agree with more.
One thing I have learned in life...people learn a subject, and then think they know the subject, and then they "know everything" which as I like to put it..."He couldn't possibly learn anything because he already knows everything!"
System7...you have formed an opinion you believe is based on "science" however, it is an opinion based on your emotional response which you have tied to your intellectual understanding of the "science" when in reality it's just your ego talking!
These Nomex164's sound great now! So don't use my name bashing domes.
Thank you!
One thing I know for a FACT...science is NEVER PROVEN! There always theories! Theories which are eventually proven wrong.
I don't care what your graphs "show". They should be used as a guide and tweaked by ear, as the post Pascal posted about this tweeter, and I couldn't agree with more.
One thing I have learned in life...people learn a subject, and then think they know the subject, and then they "know everything" which as I like to put it..."He couldn't possibly learn anything because he already knows everything!"
System7...you have formed an opinion you believe is based on "science" however, it is an opinion based on your emotional response which you have tied to your intellectual understanding of the "science" when in reality it's just your ego talking!
These Nomex164's sound great now! So don't use my name bashing domes.
Thank you!
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Clausen, I have very little emotional attachment to any particular driver. We are always really just looking for improvement. 🙂
I get a lot of fun out of loudspeakering. It is really a testing ground for different geometries which our sound waves inhabit. The same maths is used in String theory, and the surprising result of the maths is the geometry of the torus is better behaved than the sphere at high frequency:
Lecture 9 | String Theory and M-Theory - YouTube
I don't know what is controversial about the suggestion that a spherical piece of soft dome fabric flapping around uncontrollably at high frequency might not be the best way to do things. But, hey, you've got something working even if you have to notch it above 10kHz.
When Robin Marshall was talking about cone tweeters, the toroidal Vifa XT25 ring radiator wasn't even around, AFAIK. Science indeed is never proved for all time, but the maths is. The only question is whether the particular maths describes the real world.
I leave you with two images which strongly suggest that a torus is a better and more useful geometry than a sphere. There may be other solutions too which you can explore. Good luck. 😎
I get a lot of fun out of loudspeakering. It is really a testing ground for different geometries which our sound waves inhabit. The same maths is used in String theory, and the surprising result of the maths is the geometry of the torus is better behaved than the sphere at high frequency:
Lecture 9 | String Theory and M-Theory - YouTube
I don't know what is controversial about the suggestion that a spherical piece of soft dome fabric flapping around uncontrollably at high frequency might not be the best way to do things. But, hey, you've got something working even if you have to notch it above 10kHz.
When Robin Marshall was talking about cone tweeters, the toroidal Vifa XT25 ring radiator wasn't even around, AFAIK. Science indeed is never proved for all time, but the maths is. The only question is whether the particular maths describes the real world.
I leave you with two images which strongly suggest that a torus is a better and more useful geometry than a sphere. There may be other solutions too which you can explore. Good luck. 😎
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System7...I do appreciate your suggestions and help, I'm not opposed to trying the XT if I can't get these to sound right, but they seem MUCH better now. I have the XT in my center channel. I just get a little frustrated with the notion it's not possible to make these sound good when so many people like them, and I LOVED the SS D2905/9000 that was in my ACI's.
I am considering building a 3 way, and based on what your saying I might use the SS R3004 and with help here design my own XO...but that's another story and thread.
I have an extra XT....maybe I'll pick up another one and give it a try.
I am considering building a 3 way, and based on what your saying I might use the SS R3004 and with help here design my own XO...but that's another story and thread.
I have an extra XT....maybe I'll pick up another one and give it a try.
I tried the LCR circuits, and returned to the original xover, the results were really good, I was very pleased...but...it was a little TOO mellow. The LCR with values of .1 mh 1 uf and 18 r was the best, but still a little too mellow. (I also tried the .1mh, 1.5 uf and 6.5 ohms...also too mellow.)
So I tried the above, and that seems to be the ticket! Just the right amount of clarity without the harshness, and I got to listen loud today!!!! (I even listened to a Live Bluray of Cage the Elephant...very loud recording, and that guy has a high pitch voice, very ear piercing...a good test IMO of harshness. I'm very impressed.)
After a few weeks of listening I'll post back...unless I'm wrong about my initial impression!
So System7...I owe you an apology! I just wanted to make these work!!! Later I can build something better! 😉 And thank you for your HELP!!!
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Update:
Well, one day several weeks ago, I decided to do a side by side test with my old ACI's. As I said the Nomex 164 had some noticeable advantages I noticed right away after building them, but the tweeter was not one of them, which became more and more apparent.
After doing the side by side test, it was hands down the tweeter IMO. So I decided to try something of the wall. I pulled the SS D2905/9000 out of the ACI's and replaced the HDS tweeters. Then after listening added a Zobel to them.
Well I'll I can say is WOW! I know I said wow before, but since doing this, I haven't tried anything else. I'm happy now. They sound so much more musical and pleasing.
From the specs I have found I think these 9000 are 4 omh, so I'm thinking I'll try the 9500's when I have a little more room in my budget since those are 6 ohm. But other then that I don't think I'll be doing anything else until I'm ready to build new speakers!
Thanks for all the help. Some time in the near future those HDS will be for sale. Right now I put them in the ACI's since I use those in the bedroom. If anyone wants them let me know!
Well, one day several weeks ago, I decided to do a side by side test with my old ACI's. As I said the Nomex 164 had some noticeable advantages I noticed right away after building them, but the tweeter was not one of them, which became more and more apparent.
After doing the side by side test, it was hands down the tweeter IMO. So I decided to try something of the wall. I pulled the SS D2905/9000 out of the ACI's and replaced the HDS tweeters. Then after listening added a Zobel to them.
Well I'll I can say is WOW! I know I said wow before, but since doing this, I haven't tried anything else. I'm happy now. They sound so much more musical and pleasing.
From the specs I have found I think these 9000 are 4 omh, so I'm thinking I'll try the 9500's when I have a little more room in my budget since those are 6 ohm. But other then that I don't think I'll be doing anything else until I'm ready to build new speakers!
Thanks for all the help. Some time in the near future those HDS will be for sale. Right now I put them in the ACI's since I use those in the bedroom. If anyone wants them let me know!
That's in the true spirit of DIY! 😀
The replacement old classic scanspeak D2905/9000 tweeter is a bit less bright and a bit more rolled off than the D2608/9130 by the look of it.
My personal theory is that soft domes sound OK most of the time, because your brain fills in the missing detail. But when you are tired, you hear them for what they are, which is fatiguing, overly bright and lacking real detail.
It would be interesting to try a SB Acoustics ring radiator IMO.
SB Acoustics :: SB29RDC-C000-4
You'd need some attenuation.
