Zilch moved over to the QSC waveguides because others whinged so relentlessly about the lack of mouth roundover in the originals. Despite the QSC's larger dimensions, the two have basically the same control pattern, and the results should be comparable in many other respects.
'Cause nobody else ever suggested that they matter, and that it's all Zilch can do to get the on-axis response correct and the forward vertical lobe properly aimed simultaneously....
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Sorry, trying to be polite. It would have been easier on your part to just say which.🙄
Hard for me to say. Could it be that the mic is causing a reflection or?
MTF😕 I'll have never heard of that in loudspeakers. Interesting and very advanced stuff. I know some photography students who were talking about this, but I tuned them out as it was over my head.
Are you referring to the way cumulative spectral decay resonances seems to move in frequency further in time in many instances and how this relates to a WG/diffraction?
If you have any MTF demos, it would be cool to see.
Soongsc, I'm curious, would you care to share what you think are the most important things for one to measure in loudspeaker design? What must be right in your mind to make a loudspeaker worth owning/listening to? Just like a top 3 or 4 and then, briefly, why? No need to go into too much detail unless you'd like to. I'd be interested as it seems you have a lot of experience. Any further light you'd like to shed would likewise be appreciated.
Dan
A higher directivity waveguide speaker with toe-in will create a strong contralateral reflection.
Can you give us any listening impressions assuming you've heard them both over enough time and with the same driver? My intuition would tell me that the QSC would sound better, but perhaps it doesn't and my intuition isn't based on any facts I know of. I hate getting too subjective b/c it can be misleading (I just listened to the recording I mentioned as sounding harsh earlier in this thread, and wouldn't you know, it didn't sound harsh at all 😎), but would you say they sound the same or different....?
Thanks,
Dan
Markus, people who refer to themselves by their first name scare me. Dan has many irrational fears.😱
Indeed, Markus, but tell us something Zilch hasn't already. 😉
"Same driver" is the rub; I haven't worked up a crossover for the bolt-on Selenium D220Ti on QSC in eWave Deluxe yet. I'd also have to use the same woofers in such a comparison. Several Celestion drivers come in both thread-on and bolt-on variants to try as well, e.g. CDX1-1730/31. Some would argue that the deep overhang in the PE KDTrapezoid cabs will alter the outcome, masking the difference(s). I'm just not there yet, is what, for anything objectively definitive.
Personally, I think the QSC/DE250/3012LF/KDT is the best-sounding EconoWave I've built, but in a recent DIY meet where I demoed both them (Deluxe) and Standard, it was without sub(s), and Standard's extended bass skewed listening impressions. Olive's finding is correct -- extended bass is the single most significant variable in listener preferences, particularly under these "initial impression" conditions, other factors being similar.... 🙂
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Just goes to show that nobody ever reads your posts. Thats OK they don't read Earl's either. Seems like they just want to state what he believes. Stange approach that.
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Yep and that's why I go to the Biergarten now 🙂 I have the feeling there's some kind of deeper truth in taj's sig.
I believe you are referring to me and Doug in this post. I apologize for using your name at all especially if a misrepresented anything you believe--it was never my intention and FWIW I didn't bring you up and certainly didn't want to have a conversation about you. I'd appreciate if you'd point out anything I said which misrepresents you. It would clear it up for me as well as others READING YOUR POSTS. I read your posts (and Markus's🙂) CAREFULLY, but I'm sure I haven't read them all.
A couple posts from you regarding WGs and what constitutes a good WG is what I based my purchase on. Here's the reason for my last WG purchase to date:
When you said this I had already purchased one for testing based on other posts you made. These things have a smooth change in slope as best I can tell from entry to exit with the exception being both the throat(throat/CD don't match shape, area, or slope I bet) and the mouth(rather sharp discontinuation, but the best I could find at the time). I figured I could modify those parts of them. Too bad I did not realize how tough that would be to get right, but I still plan on doing it at a later date. Other cheap PE WGs are farther from your ideals than these from what you've stated. Maybe my assumption was wrong about what you meant, but these ones are the only ones that can be modified to meet your stated criteria.
Again I apologize. Nothing more I can do.
Dan
Last time I quoted Earl, it was eight or ten citations relating to the necessity of damping floor and ceiling reflections.
[I was dubbed a nut case.... 😀 ]
[I was dubbed a nut case.... 😀 ]
Those links are certainly a good read for anyone who doesn't know that info, but sort of out of context here. Doug didn't say the cone of it was heavy, just that the woofer was. His response was to refute to my comment that the Summa uses a heavier cone woofer (163g), so maybe a heavier cone woofer have better off axis performance.
This link makes a better case for geometrical stiffness: http://www.loudsoft.com/\loudsoft\my files\ALMA Paper 2003.pdf
Now where does one find the Geometrical Stiffness indicated in the parameters? Heavier may indicate stronger and/or perhaps better damped. I do not know to what degree unfortunately there's an influence. One thing is known, the B&C 15TBX100 can be integrated well with a 15" large 90 degree WG. Doesn't help DIY much at this point. There's got to be way to know the depth of a cone, stiffness of the cone and dust cap material, and how the surround will handle the break up as best I can tell if there is to be any guess not based on actual measurements.😕
Dan
Perfectly in context as I was adding the info that he didn't have to hand.
Well the mass of the entire driver incl basket and magnet etc is fairly irrelevant. In this context I took it as discussing the moving mass of the system.
I am not going to argue the cone mass vs off axis performance, because I have no info one way or the other on the subject. I included the links because it is often stated, I believe incorrectly, that the moving mass of a driver determines it's HF response.
I'll read it when I have time later.
I don't know really. Finite element analysis or the like may produce the desired info w/o measurements, but that is beyond my ability or interest.
I really don't have any preference.
Ever since the beginning of the net, there was a group of people that believed better and meaningfull discussions can be accomplished without revealing a real name because people may feel lose of face when they are well known, and their opinions are proven wrong.
How major a roll would you think this is causing? I would think the mouth termination is effecting the response in far field.
MLSSA had some of this capability in the leter versions. Newell and Hollands book on Loudspeakers touches on this subject. This is used more in optics and displays. The concept should be expanded for audio evaluation as with wavelett transforms.
How fast the initial part of the decay is, is my reference performance determining how well a speaker will reveal details. The delayed release of energy is like noise to ongoing music. It's mixed into the playback like noise. The reason we do not perceive it as noise is that it's still related with the music in someway. However, the quicker you can get rid of it, the more of the true recording you can hear.
Since MLSSA has had some of this capability, I was hoping someone else would contribute information. The last time I tried to get a used copy from the US, the original owner would not budge on the transaction fees even though I waivered the requirement for original disks and manual.If you have any MTF demos, it would be cool to see.
Speaker design and speaker final evaluation are two different things that need to be considered individually. The only reason I ventured into speaker design after retirement is that I could not find a pair of speakers that would perform to my satifaction in terms of size, fidelity, price. The initiative came when I started out in DIY back in the 80's, wrote Ted Jordan a letter asking for some specific measurements, and got the response somewhat like "We do not do these measurements, I suggest you purchase some and do your own". I still have that letter as a contant reminder, if it's something you want, you just have to go and get it yourself.
For speaker design, there is really no ground rule for me. If I find something that I am not satisfied with in listening, I just try to guess what the problem might be, do some measurements, tweak or make some test articles, and redo the measurement and listening until I find a consistent relationship.
For speaker evaluation, I would recommend the following:
1. CSD for the two time frames that I have shown. If it can be done in a large anechoic chamber, that would be the best. (note that most people that don't find CSD useful don't even show what they have measured) This should tell you what kind of sound coloration you can expect.
2. Modulation Transfer Function. I probably will find someone locally to work with in this regard. If it can be done in a large anechoic chamber, that would be the best. This will tell what kind of level of detail the speaker is capable of.
3. Wavelett transformation function (multi resolution) difference between input and output of DUT. This will tell you how the speaker alters the sound when using real recording.
4. Impedance curve. This will show how the load will interact with the amplifier, thus effect system performance.
All of the above should be conducted at at least two levels. The lowest recommended listening SPL, and the highest recommended listening SPL.
The only pair of speakers that I actually bought and still have were about USD$25 back in the 70's. They were small, good for the price, sturdy (cast aluminum enclosure). Another pair that I bought were Bose 301 back in the 80's. Only used them while I was in the US. Gave them away later.
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I never understood this concept. Confident people should not fear being wrong. Its part of the process. No one is right all the time and I would lay money on the fact that if someone fear being wrong they have limit success in life.
Anyways, some great points Songsc!!
As I posted its not the cone, other parts makes it the heaviest of all the pro drivers. I have them all so I can put one in each hand, the old fashion method 😉
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The difference between you and me is that I have 4 different tweeters (2 ribbon, 2 dome), 8 difference CDs, 7 different waveguides, 5 difference woofers, 8 different mid range drivers at this time my garage. I have measured and I have listened. You can say that isnt data too you but then again you are not exactly a DIY speaker building expert so you do not know much at this time. You do not even spend money on DIY audio to really figure things. You still think I use measurements alone. I experiment more because I have fun doing it.
I never said cost is a deciding factor on speaker building but NOT all cheap drivers sound good. Many are not nearly as close as the higher cost designs. You have never heard the TD12Ms they are better then the $100 woofers, You have never heard expensive TAD drivers or even drivers that are 3 times the price tag of what you think is a good driver (Many think its D/T!!)
There is no doubt about it to anyone that has them all. How much better is up to you. (That is the subjective side of audio.
When the experts start deeming 90deg meaurements worthy of the same focus as < 45deg measurements then we can worry about it then. For you to think you are going to change speaker design is funny when you do not even spend the $$$ to have a better rounded knowledge of all the different drivers.
Zilch posted the correct opinion. Its hard enough to get things right with many of the issues we have then jumping off a cliff with thoughts like yours.
I thought you said CSDs are meaningless? Seems like you are sort of a hypocrit to speak out of one side of your mouth to me telling me CSDs isnt data at all (insulting me as you do it with other digs) but then you are all nice to Song when he posts CSDs.
Which one is it? You either accept CSDs as part of the overall measurements data or you do not.
This whole debate about CSDs not being meaningful is stupid really because the CSD is just another way of looking at the impulse anyways. Change in the CSD means there was changes in the Impulse....Um..that means changes in what you hear.
If you want to exclude CSDs then you have to exclude the impulse which we all know is foolish.
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As an addendum to my earlier post above, I refer you'all to Joe D'Appolito's two articles: "Testing Loudspeakers: Which Measurements Matter, Part 1&2". AudioXpress Sept, and October 2008. I think he covers the OP's question quite thoroughly and in my mind, makes the 46 + pgs of discussion here somewhat moot. Those two articles were contained in a CD that came with his book on testing loudspeakers.
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