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Home » Audio » Speaker » Widerange midwoofers, specs, and x-o pts...
| Widerange midwoofers, specs, and x-o pts... [message #60972] |
Mon, 21 September 2009 21:17  |
darkmoebius2
Messages: 37
Registered: August 2009
Location: Los Angeles, CA
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Baron |
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I just wanted to open a general discussion about widerange mid drivers(3" & 4") and the most desired aspects from a specs POV.
In a perfect world, we could easily find and affordable driver capable of 80-6,500Hz FR with a nice, smooth, curve and rolloff at both ends of the spectrum. But, this isn't a perfect world.
Seeing how, in most cases, one has to crossover to both the LF and HF drivers at 1/2 to a full octave before the actual crossover point, one likely has to trade off one end of the FR against the other.
So, let me ask which is a better trait in a world of compromises (assuming one starts an array from the mids out) - extension below 120Hz or smooth highs above 3.5kHz? taking into account that comb filtering effects likely kick in above that point?
Is this a too simplistic view?
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60983 is a reply to message #60972] |
Tue, 22 September 2009 19:37  |
selahaudio
Messages: 56
Registered: September 2009
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Baron |
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| darkmoebius2 wrote on Mon, 21 September 2009 21:17 | I just wanted to open a general discussion about widerange mid drivers(3" & 4") and the most desired aspects from a specs POV.
In a perfect world, we could easily find and affordable driver capable of 80-6,500Hz FR with a nice, smooth, curve and rolloff at both ends of the spectrum. But, this isn't a perfect world.
Seeing how, in most cases, one has to crossover to both the LF and HF drivers at 1/2 to a full octave before the actual crossover point, one likely has to trade off one end of the FR against the other.
So, let me ask which is a better trait in a world of compromises (assuming one starts an array from the mids out) - extension below 120Hz or smooth highs above 3.5kHz? taking into account that comb filtering effects likely kick in above that point?
Is this a too simplistic view?
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Comb filtering doesn't remove everything so you still have to pay attention to the transfer function of your filter. There may be still be peaks and dips along the line depending on where you place your crossover and how steep the slope is.
Depending on the location and bandwidth of your subwoofer you may want to go lower than 120hz. A steeper crossover slope on the sub will also allow you more flexibility. There are more choices at say 80hz for subs but also Dayton RS / Seas 10"-12" that will easily handle a 120hz crossover point. The really long excursion drivers (15mm+ xmax) tend to be more limited because of their inductive voicecoils.
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60986 is a reply to message #60983] |
Tue, 22 September 2009 20:05 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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Rick,
RE: "Comb filtering doesn't remove everything so you still have to pay attention to the transfer function of your filter."
I'm sorry. Where does comb filtering come in here? Maybe I'm the only one who doesn't understand this, but I would like to know what you are talking about here.
I'm not assuming that its inaccurate, just that I don't know where this came into the discussion.
Thanks,
Marlboro
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60989 is a reply to message #60988] |
Wed, 23 September 2009 06:27 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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If we are taling about comb filter distortion, this is what Jim Griffin said on PE back in 2006:
"Comb lining will dull the highs and will be most noticeable in the lack of air (dull highs) especially as you move off axis. Essentially, the high frequencies are rolled off as the ensemble of the tweeter outputs don't add up but start to cancel. Now the ear is less sensitive in the upper octave (10-20 kHz) you may not observe the full impact of this effect. But if you compare to an array that is properly designed, then there is no comparison as the proper array will yield a more airy (and accurate) sound."
Jim Griffin on PE 11-21-06
If you look at a frequency chart, it looks like you put your hand over it and drew around your fingers. However if you use the proper spacing of the speakers and match the correct crossover as described in the white paper, you can avoid the issue. And if you don't move but sit still when you listen, you may not be able to hear it at all even if you have a difficult problem. Pipedreams have comb filter distortion but because people sit still, its not audible.
But I'm not sure where this subject cam up in your original discussion.
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60994 is a reply to message #60993] |
Wed, 23 September 2009 15:56 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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RE: "Domes have more interference because they radiate sound the same at all angles. If you ever listen to an array with domes you'll notice the top octave sounds partially missing and that's the result of comb filtering.The same is true for arrays with small drivers operating full-range."
You have to understand here that the only line array that Rick Craig has PROBABLY listened to that is commercially available is the PipeDreams. This may be the only line array that he has listened to with domes in it.
My research has shown that 1 inch domes are too big and 1/2 inch domes are too small. Only 3/4 inch domes will work due to comb filter distortion issues and crossover issues. And even these have to have their edges truncated so that they are literally silk to silk.
I can assure you, and everyone who has listened to my array can assure you, that there is not a hint of loss of high frequencies using my method. However, no commercial builder could possibly do it due to the labor intensiveness.
Rick has brought this up numerous times about domes, and specifically mine. Here is what Jim Griffin had to say about SPECIFICALLY ABOUT MY LINE ARRAY on April 28, 2007, when Rick Craig commented that my line array with the domes and the 3 inch midranges was very poorly executed:
"Perhaps not as bad as you are thinking. He is using 3" diameter mid-woofs with 4" pipe loading for each one. It would have been better to locate these drivers closer together so that the center to center spacing was smaller (I'm guessing about 5" c-t-c in his design[ACTUALLY 4.75 inches- marlboro]). While with his crossover at 2650 Hz would create some potential combing issues for a low slope crossover, his active crossover likely has a high enough slope to minimize the crossover overlap region between the mid-woofs and tweeters. He does trim the flanges on the dome tweeters so that their c-t-c spacing is reduced. Hence, he pushes the coherent frequency coverage for the tweeters higher than you would have without those trimmed flanges.[START OF COMB FILTER DISTORTION IS 16.5 khz--- quite a bite above my hearing and most people above 25 years old- Marlboro]
"He is a student of my white paper......"
Since I consulted with Jim every step of the way, I want to assure you that you can use domes, but you will be limited to using Dayton Neo20FA's only. Although if you can believe Zaph's reports, the little Dayton neo's charts beat all the ribbons except the B&G.
So I have to conclude that Rick's statement about domes has to be with the ones where the edges are not cut to make the center to center distance about .78. Its too bad that he lives in NC and can't hear a decent line array using domes.
Marlboro.
P.S.: If I was unable to use domes, or Dayton changed the style of their neos, i would most certainly use a ribbon. But it would be the B&G model. Until I see tests somewhere that compare all three testing graphs that John Krutke uses, I will have to use his measurements.
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60996 is a reply to message #60994] |
Wed, 23 September 2009 18:31 |
Marlboro
Messages: 403
Registered: May 2009
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Illuminati (1st Degree) |
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Back to the original question.....
I believe that distortion is the most significant measurement.
FR is so dependent on so many things from the speakers to the room to actual hearing of the individual to almost everything.
But distortion is pretty steady: IT INCREASES AS THE VOLUME INCREASES.
MARLBORO
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| Re: Widerange midwoofers, specs, and x-o pts... [message #60998 is a reply to message #60994] |
Wed, 23 September 2009 19:10 |
darkmoebius2
Messages: 37
Registered: August 2009
Location: Los Angeles, CA
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Baron |
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| Marlboro wrote on Wed, 23 September 2009 15:56 |
You have to understand here that the only line array that Rick Craig has PROBABLY listened to that is commercially available is the PipeDreams. This may be the only line array that he has listened to with domes in it.
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Marlboro, you cannot lambaste Rick for supposedly making an assumption, then turn around and make an assumption yourself about what he has, and has not, heard without seeming slightly hypocritical.| Quote: | My research has shown that 1 inch domes are too big and 1/2 inch domes are too small.
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And what do the majority of line arrays using dome tweeters utilize? So, in general, Rick's statement might be true about a lot of arrays using dome tweeters - maybe even a majority.| Quote: | I can assure you, and everyone who has listened to my array can assure you, that there is not a hint of loss of high frequencies using my method. However, no commercial builder could possibly do it due to the labor intensiveness.
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I have a feeling that you are taking every statement Rick makes too personally, as if it is intentionally directed at you. That does not seem to be the case, to me, and I think others might agree.| Quote: | Rick has brought this up numerous times about domes, and specifically mine.
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But, he did not mention you, or your array, this time. | Quote: | So I have to conclude that Rick's statement about domes has to be with the ones where the edges are not cut to make the center to center distance about .78
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How many other arrays do you know of where someone has done this? This only goes to buttress that, outside of your speakers, any array using domes the rest of us are likely to hear will be using tweeters that are not close enough together and will experience some noticeable loss in HF response.
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