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Thread: "Coloration" of horns

  1. #31
    RIP 2010 scott fitlin's Avatar
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    40,s vs 41,s

    I never said the 40,s werent good, just that I like the better top end response of the 41 diaphragm. I also have several 40,s with 41 phragms and to me that sounds really good. I have stated this in other posts as well. The 41 phragm in a 40 driver just sounds really good.

    I have heard the 2450J and 2451J and it is smoother than a 2446. But this particular neodymium is not my favorite, The TAD 4002 is. neodymium with Beryllium diaphragm! The beryllium diaphragm inside the TAD driver has no ribs, its a smooth surface dome.

    Crossover has much to do with everything, as Robh already said, and your expert is telling you.

    My guess is that for the definitive answer, why dont you call JBL, explain to them which horn/driver combination your using and ask what they recommend!
    Last edited by scott fitlin; 11-02-2003 at 04:02 PM.

  2. #32
    pangea
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    Re: 40,s vs 41,s

    Originally posted by scott fitlin
    I never said the 40,s werent good, just that I like the better top end response of the 41 diaphragm. I also have several 40,s with 41 phragms and to me that sounds really good. I have stated this in other posts as well. The 41 phragm in a 40 driver just sounds really good.

    I have heard the 2450J and 2451J and it is smoother than a 2446. But this particular neodymium is not my favorite, The TAD 4002 is. neodymium with Beryllium diaphragm! The beryllium diaphragm inside the TAD driver has no ribs, its a smooth surface dome.

    Crossover has much to do with everything, as Robh already said, and your expert is telling you.

    My guess is that for the definitive answer, why dont you call JBL, explain to them which horn/driver combination your using and what they recommend!
    I have tried to contact JBL in Sweden several times, but most of the time they haven't even replied.

    Last week I managed to talk with the head there and briefly he gave me the values on a 12 dB x-over that would lower the hump 10 dB, thus flattening the total response. Unfortunately he did not have the time to discuss the 6 dB alternative, which I would prefer if only it works as intended.

    BR
    Roland

  3. #33
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    Roland, do you mean 700Hz rather than the 7000Hz you typed? I mean, crossing over at 7000??? does the horn play at all?? If it is 700Hz, then why not simply leave it there, it's plenty low already.

    regards

  4. #34
    Administrator Mr. Widget's Avatar
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    Re: Re: Is it possible?

    Originally posted by pangea
    A close friend of mine has a pair of 2440, which he says sound better than the 2441, due to stronger magnet. He uses the 2445 diaphragms without the radial ribs, which he says are a big no no (Something with the ribs). The same ribs that are on the diaphragms in the neodymium 2451 by the way.

    In my personal oppinion, I think his 2440's sound great by the way.

    I don't think I have listened to any Be phragms yet, so I have to go with what others are saying.

    For the time being I have no choice but to use the 2445's until I can find a pair of 2440 in good condition.

    BR
    Roland
    Your friend may prefer the 2440, but it is probably due to the response peak above 8KHz when compared to the 2441s slight dip above that frequency. According to the published specifications, the 2440 does have a higher flux density than the 2441, but they use identical motors. I don't know why the numbers are different, I would guess it is due to different measuring techniques, but I am not sure. In any event what Scott has been saying is true. The aluminum diaphragms do have lower distortion and I and most people I have talked to prefer their sound quality over the titanium diaphragms. You certainly can interchange the 2440, 2441, and 2445 diaphragms in all three motors. I am not sure, but I would guess that the 2441 or 2440 diaphragm in the 2445 driver would probably sound virtually identical to a stock 2441 or 2440 despite it's use of ferrite instead of alnico. If you use the 2445 diaphragm in the 2440/2441 motor you will get an extended HF output and different sound character, one that you may prefer, but for accuracy and lower distortion I would recommend the 2441 diaphragm. On a related note as was pointed out by Bo on another thread changing his older aluminum diaphragms for new ones of the same design made a huge improvement due to the aging of the diaphragm's surrounds. This is also a possible explanation for your friend's preference. He may have compared old 2440 diaphragms to new Ti diaphragms.

    As far as Be is concerned. TAD has always used it as they have always produced a line of cost no object drivers. Yes JM labs is now using it in their extremely expensive speakers and even our own JBL is now using it in their flagship K2-S9800s. It seems that the material is universally accepted as the superior material if cost is no object.

  5. #35
    pangea
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    Originally posted by Guenter
    Roland, do you mean 700Hz rather than the 7000Hz you typed? I mean, crossing over at 7000??? does the horn play at all?? If it is 700Hz, then why not simply leave it there, it's plenty low already.

    regards
    Hi Guenter!

    Which post are you referring to?

    BR
    Roland

  6. #36
    pangea
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    Re: Re: Re: Is it possible?

    Originally posted by Mr. Widget
    Your friend may prefer the 2440, but it is probably due to the response peak above 8KHz when compared to the 2441s slight dip above that frequency. According to the published specifications, the 2440 does have a higher flux density than the 2441, but they use identical motors. I don't know why the numbers are different, I would guess it is due to different measuring techniques, but I am not sure. In any event what Scott has been saying is true. The aluminum diaphragms do have lower distortion and I and most people I have talked to prefer their sound quality over the titanium diaphragms. You certainly can interchange the 2440, 2441, and 2445 diaphragms in all three motors. I am not sure, but I would guess that the 2441 or 2440 diaphragm in the 2445 driver would probably sound virtually identical to a stock 2441 or 2440 despite it's use of ferrite instead of alnico. If you use the 2445 diaphragm in the 2440/2441 motor you will get an extended HF output and different sound character, one that you may prefer, but for accuracy and lower distortion I would recommend the 2441 diaphragm. On a related note as was pointed out by Bo on another thread changing his older aluminum diaphragms for new ones of the same design made a huge improvement due to the aging of the diaphragm's surrounds. This is also a possible explanation for your friend's preference. He may have compared old 2440 diaphragms to new Ti diaphragms.

    As far as Be is concerned. TAD has always used it as they have always produced a line of cost no object drivers. Yes JM labs is now using it in their extremely expensive speakers and even our own JBL is now using it in their flagship K2-S9800s. It seems that the material is universally accepted as the superior material if cost is no object.
    Hmmm...

    You may well be right there.
    Interesting that the 2440 and 2441 are using the same motor and therefore should have the same flux.

    I'll try to get hold of a pair of 2441 diaphragms, I know a person who's got a few from a bankruptcy auction.

    The TAD's are way out of my league.

    BR
    Roland

  7. #37
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    Roland, your very first post in this thread.

    -regards

  8. #38
    PSS AUDIO
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    Re: drivers

    Originally posted by scott fitlin
    The 2441 diaphragm sounds really good in a 2440 driver, I know, because I have done it.
    Hello Scott,

    I was said that the only difference between a 2440 and a 2441 was the diaphragm?

    Is it right?

    How can I recognize a 2440 than a 2441 as their is no more rear plates?

  9. #39
    pangea
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    Originally posted by Guenter
    Roland, your very first post in this thread.

    -regards
    OK, I had a pair of 16Ohm HP 7000Hz x-overs on the shelf, so I simply tried them out for comparison, just to see if there was any coloration left, but there was none, so I figured there maybe was i magical line which one shouldn't cross.
    Little did I know that it's when you go to low for the intended horn and tap in to the unloaded frequencies, when the problem with coloration occurs.

    But thanks to you guys on this great forum, I have learned alot already.

    THANKS!!!

    BR
    Roland

  10. #40
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    [QUOTE]Originally posted by pangea
    [Little did I know that it's when you go to low for the intended horn and tap in to the unloaded frequencies, when the problem with coloration occurs.

    It is not the low, unloaded, frequencies that are the problem. As I understand it form Drew Daniels, see his comments yourself elsewhere on this site, the problem mainly arises because of the possibly mismatched off-axis response near the xover frequency
    of the two drivers. Case in point is the typically 500Hz crossover point used between the 15" base driver and the horn. While the former is starting to beam, the latter is essentially omnidirectional. Makes much sense and, aferall, he should know.

    -regards

  11. #41
    Administrator Mr. Widget's Avatar
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    Re: Re: drivers

    Originally posted by PSS AUDIO
    Hello Scott,

    I was said that the only difference between a 2440 and a 2441 was the diaphragm?

    Is it right?

    How can I recognize a 2440 than a 2441 as their is no more rear plates?
    With the newer 2440/2441 there is no physical difference between them. If you open the back and it has a 2440 diaphragm it is a 2440, conversely if the diaphragm is a 2441... You can tell the diaphragms apart by two things, first the surround is a simple concentric crimp in the 2440 and a series of diamond shaped radial dimples in the 2441. Also the 2441 has a small dot applied to the center of the diaphragm.

    If you have an older driver with the flat back it would have to be a 2440/375 as all of the 2441/376s were done with the chamfered back cap.

  12. #42
    TimG
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    There are advantages and disadvantages to all of the diaphragm materials being discussed. If you already have 2445 drivers your choices for "new" diaphragms are limited to 2441 aluminum, 2445 bare titanium and 2450SL coated titanium. I have heard from 3 sources that JBL has stopped making the 2441 domes, so buy them fast if you want them. I would expect the titanium domes to be available well into the future, unless JBL starts phasing out all of the 4" drivers and uses only 3" and 1.75" drivers in their newer products. Since titanium has much better fatigue resistance than aluminum, they would last longer if used with the same amount of power. This may be something to think about if you buy 2441 domes now and need to replace 1 in the future.

    If you want berrylium diaphrams now, you will have to buy TAD drivers. Cost is the big issue with these drivers. You can get JBL aluminum or ti domes for $150 now but I the TAD replacement domes sell for around $650 each.

    With any of these compression drivers, I would stay away from 6dB per octave crossovers unless you want to spend a lot of money on replacement diaphragms.

    People have previously mentioned the improved transient response of first order networks, but the schematic you posted is not a first order acoustic network, and first order networks need to meet special criteria to have the advantages of first order acoustic networks. The theoretical advantages of first order acoustic networks only apply when the driver in question, in combination with the cabinet and network, produces an acoustic response that matches the first order response curve. Achieving this is a lot more complicated than it sounds, and will definitely not be achieved with a single element (capacitor or inductor) crossover. A single element crossover will create a first order electrical network, but a first order electrical network does not give you a first order acoustical response curve. To build a true first order acoustic crossover normally requrires mutiple components and equilization circuits to approach a first order acoustical response, and it will almost always require more components than say a 4th order LR crossover. When trying to reach a crossover acoustical target one has to consider both the inherent driver response mounted in a specific horn or baffle, as well as the transfer function of the electrical components of the crossover.
    From this site http://www.ijdata.com/ you can download a demo version of the LspCAD crossover design software and experiment with crossover design with some sample drivers. You can experiment with passive and active crossovers and target different acoustic slopes using the optimizer, such as first order, and 4th order LR. Being able to see graphically the changes that different components makes in the crossover makes it easier to see why true 1st order acoustic crossovers are difficult to build.
    There is also a small file that you can download at this site to see if you can hear the difference between a not distorted sqaure wave at 1000Hz and a wave distorted by a 4th order acoustic network.

  13. #43
    RIP 2010 scott fitlin's Avatar
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    Yup!

    But as Tim says, and I said already, I would not use a first order network with compression drivers, and especially crossing over at 500hz!

  14. #44
    pangea
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    Originally posted by TimG
    There are advantages and disadvantages to all of the diaphragm materials being discussed. If you already have 2445 drivers your choices for "new" diaphragms are limited to 2441 aluminum, 2445 bare titanium and 2450SL coated titanium. I have heard from 3 sources that JBL has stopped making the 2441 domes, so buy them fast if you want them. I would expect the titanium domes to be available well into the future, unless JBL starts phasing out all of the 4" drivers and uses only 3" and 1.75" drivers in their newer products. Since titanium has much better fatigue resistance than aluminum, they would last longer if used with the same amount of power. This may be something to think about if you buy 2441 domes now and need to replace 1 in the future.

    If you want berrylium diaphrams now, you will have to buy TAD drivers. Cost is the big issue with these drivers. You can get JBL aluminum or ti domes for $150 now but I the TAD replacement domes sell for around $650 each.

    With any of these compression drivers, I would stay away from 6dB per octave crossovers unless you want to spend a lot of money on replacement diaphragms.

    People have previously mentioned the improved transient response of first order networks, but the schematic you posted is not a first order acoustic network, and first order networks need to meet special criteria to have the advantages of first order acoustic networks. The theoretical advantages of first order acoustic networks only apply when the driver in question, in combination with the cabinet and network, produces an acoustic response that matches the first order response curve. Achieving this is a lot more complicated than it sounds, and will definitely not be achieved with a single element (capacitor or inductor) crossover. A single element crossover will create a first order electrical network, but a first order electrical network does not give you a first order acoustical response curve. To build a true first order acoustic crossover normally requrires mutiple components and equilization circuits to approach a first order acoustical response, and it will almost always require more components than say a 4th order LR crossover. When trying to reach a crossover acoustical target one has to consider both the inherent driver response mounted in a specific horn or baffle, as well as the transfer function of the electrical components of the crossover.
    From this site http://www.ijdata.com/ you can download a demo version of the LspCAD crossover design software and experiment with crossover design with some sample drivers. You can experiment with passive and active crossovers and target different acoustic slopes using the optimizer, such as first order, and 4th order LR. Being able to see graphically the changes that different components makes in the crossover makes it easier to see why true 1st order acoustic crossovers are difficult to build.
    There is also a small file that you can download at this site to see if you can hear the difference between a not distorted sqaure wave at 1000Hz and a wave distorted by a 4th order acoustic network.
    What about Diaphragms made by for instance Radian, which supposedly are made at the same factory? Wouldn't that work for the time being, or is the quality inferior on those phragms?

    Where would you set the crossover point IF you would have to go for the 6 dB slope for any reason?


    I think I've managed to go around some of the problems you mentioned though, by putting the driver in a loose top cabinet, which is adjustable in all directions, except up and down.

    I tried the demo version of the (Swedish) LspCAD but unfortunately it was restricted to 4th order calculations only.

    Also I listened to the sound file through my computer, but wasn't able to hear any differences apart from a faint "clicking" sound in the middle. But then again, maybe I wasn't supposed to even?

    BR
    Roland

  15. #45
    TimG
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    I have no personal experience with the Radian replacement diaphragms, but other people have had good experiences with them.

    Are you asking about a 6dB electrical or acoustic crossover? I would not recommend a 6dB acoustic crossover on a 2" throat compression driver. Compression drivers just don't have the excursion to handle 6dB acoustic slopes. A 6dB electrical network is not going to give you a 6dB acoustic slope, so without modelling software you can't know exactly what you are going to end up with.

    I would contact Ingemar about that issue. I have the full version of the program and it was a bargain if you are going to be doing any serious speaker building. LspCAD basic includes the modelling software and a basic MLS measurement system. All you need is a sound card like the Soundblaster Live and a Panasonic microphone capsule and you can get actual measurements of the drivers you are using. Even without calibration files the Panasonic capsules are accurate, only rolling off in the top octave. The program includes instructions on making a simple system with some resistors to obtain impedance readings on your driver, which is critical for developing accurate crossovers.

    If this seems like too much work or expense, here is my suggestion for the safest solution for the drivers you are working with. Just buy the JBL 3107 crossover from the tent sale. I'm sure someone here would help you with shipping the crossover to Sweden for you. This is the crossover for the upper 3 drivers from the 4350 and the 2311 horn used in this model is very similar to the horn you are using. You could probably even add a 2308 lens to your horns and get even closer response. The 3107 will give you adequate protection so you don't blow your compression driver and you could add a 2202H and a 2405 and be set for the top 3 drivers of a 4 way system.

    The point of the sound file is to see whether you can hear the impulse distortion caused by a 4th order crossover (the sound after the click) versus the lack of impulse distortion from a transient perfect crossover (the sound before the click). If the difference isn't offensive to your ears, that implies that you won't find a 2nd, 3rd, or 4th order acoustic crossover offensive.

    Here is an excellent page link that shows the impluse response of some different crossover slopes and the necessary conditions for a 6dB acoustic crossover to have perfect impulse response. If there is too much traffic at the site you may not be able to link to it so try again in an hour. http://www.geocities.com/kreskovs/TimeAligned1.html
    http://www.geocities.com/kreskovs/Phase-B.html
    Main site http://www.geocities.com/kreskovs/John1.html

    There are many disadvantage to 1st order acoustic crossovers that sometimes don't get mentioned. I will admit my bias that I don't believe they are the ultimate crossover. One reason is that the severly reduced protection of the drivers from overexcursion will increase distortion dramatically, and greatly increase the risk of damaging your expensive compression drivers. Isn't low distortion and wide dynamic range one of the reason you went with compression drivers in the first place?

    If anyone can take measurements of amplitude and impedance on your driver on your horn I can help you design a crossover. I have both LspCAD and Soundeasy modelling software.

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