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Thread: New versions of old classics

  1. #1
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    New versions of old classics

    Hi guys!

    I am new to this forum, so I hope I do things correctly.

    One thing has been on my mind for a while. There are lots of classical and very popular drivers from JBL, Altec Lansing and others. Just to mention a few cone drivers from the top of my head:
    JBL E145
    JBK 2220
    Altec Lansing 515
    TAD 1601b

    ...and there are off course many others.

    But what if one should make new drivers that would work as drop in replacement for any of these. What would be important? What really makes those drivers so popular? I assume the fact that they are obsolete gives them a kind of exclusivity, but things like high VAS, strong motors and low moving mass are things you do not see as often today as back in the days.

    I am currently working on a 15 inch with parameters similar to the TAD 1601b, and some discussions are going on about what is most important. It is currently at 400 liters VAS and has a motor characteristic and moving parts that gives it the same low end response as the 1601 in bass reflex cabinets. However, it also differs in important areas. For example, instead of an alnico motor, it has a compact neodymium motor. It also has way lower Le, longer x-max, and a 100% symetrical differential drive motor. Off course it also has less progressive suspension due to the longer x-max.

    What I want to discuss here is...:
    - Why do we like the old classics?
    - Which ones of the old classics are really interesting today?
    - What would be important parameters to keep if one were to make a new drop in replacement?
    - And which parameters should we allow ourselves to change?

    I just attach an image to make the post look better
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  2. #2
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Snickers View Post
    What I want to discuss here is...:
    - Why do we like the old classics?
    - Which ones of the old classics are really interesting today?
    - What would be important parameters to keep if one were to make a new drop in replacement?
    - And which parameters should we allow ourselves to change?
    There is a review of the current Klipschorn in this month’s Stereophile. The review praises the speaker’s strengths but also acknowledges its shortcomings. My takeaway from the review is the honest assessment that every speaker is an assortment of compromises. The classic speakers that many of us admire are extremely dynamic... a feature rarely shared by most modern hi-fi speakers today. This is true of drivers and complete systems.


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  3. #3
    Senior Member Odd's Avatar
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    Welcome to Lansing Heritage Forums Jørn.

    "Snickers" is a well-known figure on Norwegian forums and has considerable technical expertise.

    He has also held courses on DSP and other HIFI related material. YouTube link

    He has now started an ambitious project to create a new bass driver.
    More info on new bass driver here. (Content in Norwegian)
    43XX (2235-2123-2450-2405-CC 3155)5235-4412-4406-4401-L250-18Ti-L40-S109 Aquarius lV-C38 (030) 305P MkII

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    Administrator Mr. Widget's Avatar
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    Very cool! Thank you Odd, for the introduction.

    Yes, welcome to the Forum, Snickers! Please tell us more.


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    Senior Member macaroonie's Avatar
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    Welcome Snickers from just across the water. M

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    Thanks so much all of you for the warm welcome!

    For those who want to follow the driver I am currently working on, I would like to recommend the DIY Audio-thread, as I guess English comes more naturally for most of you guys than Norwegian does. Here is the link:

    https://www.diyaudio.com/forums/mult...ch-woofer.html

    For those of you familiar with simulations and T/S-parameters, you will probably notice right away that it does not have the exact same parameters as the TAD TL1601b, but the response in the target enclosure (150 liter/24Hz) is as close as you could possibly get it.

    If we look at the old JBL tech-stuff from around 1978 (when the crisis in Kongo started, making cobalt an extremely expensive material). They did some work on how to better take advantage of the properties of ferrite. The drivers originally available with both alnico and ferrite were almost always far better with alnico than with ferrite. However, when they seriously undercut the pole piece (getting it pretty much saturated at the bottom) the performance improved even past the performance of alnico drivers.

    With modern simulation tools, such as FEMM/COMSOL etc, we know today that this is closely connected with the saturation level in the steel parts, and, even if it could mean being shot dead in a dark back yard to even mention it, alnico by itself is not necessarily better than ferrite if the saturation level in the steel parts is the same. We do not see drivers where this is identical between an alnico version and a ferrite version. Drivers available with both ferrite and alnico are pretty much allways far more saturated in the alnico version, so it should also sound better.

    My point is not to discredit alnico in any way, and especially not to discredit any great drivers with alnico. But I would like to point out that, as JBL also found out in the 70's, there are ways to engineer a motor to improve performance significantly, regardless of magnet material. The overall geometry of the motor is really depending on what kind of magnet material you use. In the current driver, I get pretty small steel parts as the N40 magnets gets enough space inside the voice coil, so that I do not have to worry about reaching out to the edge of a 300mm ferrite ring. I do get around 2,2 Tesla in the pole tips. Everything above 1,95T should be regarded saturated for most types of steel, and above 2,1T the B/H-curve is pretty flat.

    So with todays technology, we can achieve the alnico benefits, but with a more effective motor geometry.

    There are, however, some of the old drivers that uses some interesting and rather odd solutions. Some of the vintage compression drivers do use silver shorting rings, which is quite interesting from a high frequency standpoint. Then you have one driver in the E-series, I do not remember which one, that uses an equal hung motor geometry. That is pretty much useless for a woofer, but as a mid bass horn driver that has probably less than 1mm excursion at max, it could be interesting. I do not suggest making an equal hung motor, but I think making a really short x-max driver (that has an extremely light coil and cone, and insane motor force) could be an interesting thing. The E145 is also popular. But as JBL stated back in the days, they are not for music reproduction, they are for music production. And then, if I got my facts right, they went on to use it in the Everest... Probably due to its lively midrange.


    So I'll try to rephrase a bit. Which drivers would you like to see new versions of?

    That could potentially form a base for which drivers to discuss. Then we could look more into what makes those drivers special. We could also discuss what should be changed or added. A good friend of mine just replaced his 2226 (i think) with 2220. He is a bit worried about loosing the shorting rings, but really liked the sound of the 2220s. This is just an example of what I mean with "things that should be changed or added". I've got to invite him to this thread. I think he has read all documents in the world that says JBL, Altec Lansing or GPA somewhere on it.

    At the moment we are, in a way, discussing all drivers at once. That was probably not the best idea.

  7. #7
    Member oks81's Avatar
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    Hello!

    I have tried to read some JBL yes..but som of the guys in this forum probably do know more than me.
    First the equal hight voicecoil/gap 15" driver you mention is the E130.
    This is an instrument driver, but can`t see anything wrong with using it for horn and midrange in hifi setup.
    As it is equal hight it is very efficient for it`s application, but off course very short stroke.
    The specs says Xmax 2,5mm, the VC is then out of the gap so I don`t know how the linearity of this driver is at 2,5mm.

    In my setup I hva tested the 2226, 2227 and 2220.
    Tried to compare the 2227 and the 2220 in the range of 150-600hz.
    The 2220 is maybe the one I prefer. It is a little more efficient, underhang motor, curvelinear cone and quite high Vas.
    My 2220 is the H model with ferrite motor. Could be interesting if this driver had some of the features from the 2227 motor, as copper shorting rings.
    The 2227 sounds good at the same application, and that tells me that the SVG motor has something to it.
    Both the 2227 and 2220 is quite a bit bether than 2226 in the midrange.


    Your driver Snickers, is more in the range of Altec/GPA 515, JBL E145, TAD 1601.
    Both 515 and E145 has underhang motor.
    The TAD probably overhang since higher Xmax.
    All three quite high Vas and not so high mms.
    Classic drivers used to play all the way from bass and up to a horn in typical two way setup.

    The GPA 515 quite expensive these days, E145 is not made anymore, TAD 1601 quite expensive, is it only NOS that is sold at proaudiodesign?
    Think your driver should be welcome in the application for bassreflex to play all the way up to 6-800hz.
    Remember the history!

  8. #8
    Member oks81's Avatar
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    In the specs of the E145 it has Vas of 275 litres.
    This I have read that is wrong, and should be 428 litres.
    Had to test this in VituixCad and seems like 428 litres is correct.

    Name:  JBL E145 simulation.jpg
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    Mms is quite low on this driver with 55 grams.
    Never heard it but can imagine it sounds nice
    Remember the history!

  9. #9
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Snickers View Post
    So I'll try to rephrase a bit. Which drivers would you like to see new versions of?
    Now that you put it that way...

    My favorite classic woofers have been the light coned vintage JBLs. 2220A, K130, K145. The fact that all three are alnico may or may not have been all that important. None are great at deep bass, but they have a “liveliness” that I find very desirable. The first two have curvilinear cones and the K145 is a straight sided cone and all three have very different motor structures.

    I haven't really studied the differences, but look forward to your thoughts and discoveries.

    Now, that’s woofers... what about HF drivers? My favorites there are all 4” diaphragmed compression drivers with either 2” or 1.5” exits. The models I have owned and liked in no particular order, JBL 2440, 2441, 476Be, and from TAD the TD-4001 and TD-4003.


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  10. #10
    Member oks81's Avatar
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    Offcourse!
    The K-series is the alnico and the E-series is ferrite.
    Never stop learning!
    Remember the history!

  11. #11
    Senior Member RMC's Avatar
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    Hi OKS 81,

    RE post # 7: "First the equal hight voicecoil/gap 15" driver you mention is the E130.
    This is an instrument driver, but can`t see anything wrong with using it for horn and midrange in hifi setup.
    As it is equal hight it is very efficient for it`s application, but off course very short stroke.
    The specs says Xmax 2,5mm, the VC is then out of the gap so I don`t know how the linearity of this driver is at 2,5mm."

    The following, discussing The Magnetic Motor Structure, should clarify the above matter. But I'm not sure someone would really want this in a Hi-Fi type setup:

    "The form shown in figure 2-3b [RMC: voice coil and top plate of equal length] concentrates all of the flux in the coil at its rest position. It is evident that even moderate excursions of the voice coil will result in some loss of total flux engaging the voice coil, thus producing distortion. This design is common in very-high-efficiency drivers used for musical instrument amplification, where some degree of distortion may indeed be sonically beneficial." [John Eargle (JBL), Loudspeaker Handbook, P. 23-24]

    Best Regards,

    Richard

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    Member oks81's Avatar
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    Thanks for reply Richard!
    Yes I agree that this driver should be used with care in hifi.
    Remember the history!

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    Quote Originally Posted by RMC View Post
    Hi OKS 81,

    RE post # 7: "First the equal hight voicecoil/gap 15" driver you mention is the E130.
    This is an instrument driver, but can`t see anything wrong with using it for horn and midrange in hifi setup.
    As it is equal hight it is very efficient for it`s application, but off course very short stroke.
    The specs says Xmax 2,5mm, the VC is then out of the gap so I don`t know how the linearity of this driver is at 2,5mm."

    The following, discussing The Magnetic Motor Structure, should clarify the above matter. But I'm not sure someone would really want this in a Hi-Fi type setup:

    "The form shown in figure 2-3b [RMC: voice coil and top plate of equal length] concentrates all of the flux in the coil at its rest position. It is evident that even moderate excursions of the voice coil will result in some loss of total flux engaging the voice coil, thus producing distortion. This design is common in very-high-efficiency drivers used for musical instrument amplification, where some degree of distortion may indeed be sonically beneficial." [John Eargle (JBL), Loudspeaker Handbook, P. 23-24]

    Best Regards,

    Richard
    I did an experiment on this. An E130 in a long midbass horn with 1/4,5 loading. Half space, 2,83V, voltage source is shown here:

    Name:  Skjermbilde 2019-09-01 01.30.28.png
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    Name:  Skjermbilde 2019-09-01 01.29.40.png
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    In real world, you would get even more SPL as half space is wider than what you would get out of this horn.

    In this application, the driver will rarely pass 0,1mm excursion. At 0,8mm we are past 125dB for each channel, that's way past 130dB total. The relative distortion would be low even though the BL(x) curve looks quite bad.

    As a low end driver, it is pretty much useless.

  14. #14
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    Quote Originally Posted by Snickers View Post
    I did an experiment on this. An E130 in a long midbass horn with 1/4,5 loading. Half space, 2,83V, voltage source is shown here:

    Name:  Skjermbilde 2019-09-01 01.30.28.png
Views: 365
Size:  11.9 KB

    Name:  Skjermbilde 2019-09-01 01.29.40.png
Views: 363
Size:  12.9 KB

    In real world, you would get even more SPL as half space is wider than what you would get out of this horn.

    In this application, the driver will rarely pass 0,1mm excursion. At 0,8mm we are past 125dB for each channel, that's way past 130dB total. The relative distortion would be low even though the BL(x) curve looks quite bad.

    As a low end driver, it is pretty much useless.

    interested project you are working on
    can you check how 2254J will work in mid bass horn?




    Ari

  15. #15
    Senior Member RMC's Avatar
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    To oks 81:

    Thanks for the E-145 Vas number confirmation "Had to test this in VituixCad and seems like 428 litres is correct." Another source adds even more weight to the correction. I already had a note in my Winspeakerz software about this since 427 litres was previously mentioned but I never knew where the source of the problem came from (the two numbers don't even look the same so not a typo?) and 275 litres didn't seem like a patently unreasonable number to me in view of other similar size drivers' data.

    The new number represents a good increase and that also means an increase in appropriate box size for the E-145 driver... Possibly one reason, along with Qts, why JBL never specified the E-145 in their rear-loaded folded horns 4520/4530 for example.

    Btw I like your Avatar picture, looks partly serious and partly cartoon (with wires at the back), very nice.

    To Snickers:

    I like your simulations they appear convincing.

    However, "An E130 in a long midbass horn..." for a Hi-Fi setup? To me a Hi-Fi setup means a normal size room in a standard home, not a millionaire's mansion or palace size audio room.

    And in relation to this Horn expert Bruce Edgar mentions the following about room size and horns (exponential it seems):

    "The problem with horns is that you still need a large room for them to work properly. Some customers have asked about putting horns in a very small room, like 10 x15 feet or even smaller, and I have to tell them I can't recommend horns for a room that small. You need a larger room, and the bigger the room the better because horns just sound better in the far field, unlike direct radiator speakers." (Positive Feedback, Issue 4, Dec./Jan. 2003)

    RE: "As a low end driver, it is pretty much useless."

    I don't disagree with you for high-output low bass, but I do note member MoD here (thread MoD is playing with the Lansing heritage :-) did make one or two bass horns with the E-130 or similar if my memory is correct and he seemed satisfied with his results. Naturally, this always depends on each person's expectations and what satisfies them, some need to rattle the whole neighborhood to feel good, while others are gratified with less than that...

    Best regards,

    Richard

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