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Thread: New versions of old classics

  1. #16
    Member oks81's Avatar
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    If the Vas on the E145 is correct at 275 litres, that will increase both mms and BL.
    Lets hope it`s only one parametre that is wrong, and the Vas should be 428 litres

    The avatar I do also like, a guy in Norway drawn it for me.
    It`s of my compact living room speakers....

    Name:  JBL OKOB.jpg
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    The bass department is open baffle.
    2x2226 and 2220 at top.

    I do look at interest at the E145 with its low mms, high vas and lower fs than the 2226, maybe E145 would do a bether job than 2226...?
    But it`s not exactly easy to find four E145 in good condition..
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  2. #17
    Senior Member macaroonie's Avatar
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    Its always good to check Hi Fi Shark


    https://www.hifishark.com/search?q=jbl+e145

  3. #18
    Member oks81's Avatar
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    Please don`t tempt me
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  4. #19
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    Quote Originally Posted by hlaari View Post
    interested project you are working on
    can you check how 2254J will work in mid bass horn?

    Ari
    I'd be happy to do that, but the data I have found on that driver does not add up at all. I think there has to be at least two fundamental errors in the data on that driver.

  5. #20
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    Quote Originally Posted by Snickers View Post
    I'd be happy to do that, but the data I have found on that driver does not add up at all. I think there has to be at least two fundamental errors in the data on that driver.
    VAS 2.6 cu.ft = 73.62l
    BL 10.99 (is definitely wrong measurement) should be more around 25?




    Ari

  6. #21
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    Quote Originally Posted by hlaari View Post
    VAS 2.6 cu.ft = 73.62l
    BL 10.99 (is definitely wrong measurement) should be more around 25?




    Ari
    Have you measured it? Or do you have a reliable source? There is always this challenge of knowing which parameters are correct, and which are wrong.

  7. #22
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    Quote Originally Posted by hlaari View Post
    VAS 2.6 cu.ft = 73.62l
    BL 10.99 (is definitely wrong measurement) should be more around 25?
    Ari
    I did a quick run in Fine Motor. I get parameters adding up when I use your cubic feet variant, and assume the force factor is completely off. I ended up with 41,3.

    This is what I got in the same horn as with the E130:
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    The higher mass probably means you could use a bit less compression. However, this is not more than 1:3, so it should not be a problem.

  8. #23
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    Quote Originally Posted by Snickers View Post
    Have you measured it? Or do you have a reliable source? There is always this challenge of knowing which parameters are correct, and which are wrong.

    I found this info for thiele/small parameters for 2254j
    http://petoindominique.fr/php/mysql_...ul.php?hp=5760




    Ari

  9. #24
    Member oks81's Avatar
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    Got almost the same in Vituix.

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  10. #25
    Senior Member RMC's Avatar
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    Hi oks 81,

    RE: post # 16, "I do look at interest at the E145 with its low mms, high vas and lower fs than the 2226, maybe E145 would do a bether job than 2226...?"

    Personnaly, I'd be more interested in E145 lower Qts VS 2226, instead of E145 lower Fs than 2226 for what you seem to be looking for. My understanding, right or wrong, is that you may be looking for a more dynamic driver in E145. Dynamic here not equal to absolute driver output but rather one having better transient response. e.g. there's some of these in older JBL drivers, the 2220 you have could be one of them.

    The 5 hz difference in Fs between E145/2226 isn't a big gain and possibly not really what would put you ahead in your quest. In my view the E145 lower Qts than 2226 might be more rewarding dynamics wise than the Fs aspect.

    As indicated by Bullock, low Qts drivers tend to have better transient response, same for flat enclosure alignments. For the latter, Eargle showing Small's work on this, for sealed and vented, is more than clear. Could be why I really like the sound of my good old 2205H drivers, they're fast/dynamic, even though not up to more recent standards in terms of low-frequency capability and spl output.

    BTW since you appear to have an interest in LF driver BL and other TS, plus me having an interest in LF driver Qts and other TS, well here's the relation between these two as mentioned by Eargle (Loudspeaker Handbook, P. 61):

    " Figure 4-3 shows a family of curves in which the value of Qts is the only variable. This is roughly equivalent to varying the BL product of the driver. Reducing BL (increasing Qts) diminishes the piston band sensitivity of the system, while allowing the response at system resonance to peak progressively higher, relative to the piston band value." Then he mentions that design trade-offs are made on the basis of T/S analysis. So, the above suggests BL and Qts evolve in opposite directions (roughly), plus incidental effect on sensitivity and system response.

    Best regards,

    Richard

  11. #26
    Member oks81's Avatar
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    I dont know the answer since it`s OB.
    But could be interesting to test.
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  12. #27
    Member oks81's Avatar
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    Do the K130 have equal hight VC/Gap as the E130?
    And do the K145 have underhung motor as the E145?

    Anybody who knows?
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  13. #28
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    Quote Originally Posted by Mr. Widget View Post
    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.
    I do not have all that in depth knowledge about all of these, but I assume the parameters are not too far from the E-series counterparts.

    The E130 and K130 are absolutely useless for any kind of bass application. It has to be considered a pure midrange. It should also have relatively low inductance and insanely low mass combined with high efficiency. The high efficiency comes from botn a 100% coil/gap-coverate (100% of the coil covers 100% of the gap) that gives a really strong force factor, and off course, the low moving mass.

    The sound of these drivers comes partially from distortion caused by motor induced distortion, but for applications where the excursion is extremely short, it will be heavily influenced by the fact that this driver creates a massive sound pressure with almost no load on the magnetic circuit. It also has a short and lightweight coil, which makes life easier for the cone. Las, but not least, a driver like this can use light suspension.

    It is not hard to make a replacement driver for it, but I am not all too sure people would really want it exactly as the original.

    The K145 is, IMO, more interesting. It can be used as a woofer, but at the same time, it represents something a bit special for midrange. It is popular for midbass horns too. It too does have a rather limited x-max. Making a new version of it could be interesting, but I would probably rather give it a good 8-10mm x-max than the 5mm of the original. This can be done without compromising on other parameters.

    The 2220 is not that different from the K145, but has a slightly stronger motor. I guess a "New version" could cover both of them for most applications. The E145 and the K145 are more different than the K145 and the 2220A, so they are not very far from each other any of these.


    Quote Originally Posted by Mr. Widget View Post
    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.
    I am on this, but at the moment, I am concentrating on cone drivers.

    The things I have been looking at is a large format 3 inch with 2 inch throat (a bit like the Altec 288, but with a beryllium option) and give it more extension in both ends than the typical 4 inch drivers out there.

    I have also been asked for a small driver for super tweeter, like the TAD 703 and others. Maybe as a driver with 0,75 inch throat.

  14. #29
    Administrator Robh3606's Avatar
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    The K145 is, IMO, more interesting. It can be used as a woofer, but at the same time, it represents something a bit special for midrange. It is popular for midbass horns too. It too does have a rather limited x-max. Making a new version of it could be interesting, but I would probably rather give it a good 8-10mm x-max than the 5mm of the original.
    The K145 and E145 are short coil log gap so the coil is 100% in the gap even at extremes. The E has significantly longer xmax about a 3rd more. You are going to end up with a very thick top plate and end up needing subs anyway if you keep everything else the same.

    Rob
    "I could be arguing in my spare time"

  15. #30
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    Quote Originally Posted by Robh3606 View Post
    The K145 and E145 are short coil log gap so the coil is 100% in the gap even at extremes. The E has significantly longer xmax about a 3rd more. You are going to end up with a very thick top plate and end up needing subs anyway if you keep everything else the same.

    Rob
    Yes, they are under hung. I really loved the idea of under hung for some time, but after a while I discovered that the flux is extremely unstable in a long gap. One could make it stable, but for a 20mm tall gap, that requires a lot more magnet than you find in the K or E 145. The problem can be seen two ways. One is that the flux tends to move from the part of the steel with load, to a part of the steel without load. So even if the coil has 100% coverage, the gap has not. Another way to see it, which is kind of different, but at the same time represents the same thing seen from a different perspective, is that having a narrow gap covering the entire coil makes the inductance go fairly high for a coil this size. A lot of steel is available at all times, and it all contributes to slow down current in the coil and convert it to magnetic flux in the steel itself.

    We also have a huge benefit using a king of geometry like this, and that is the fact that the coil is light, and you can lower the total moving mass.

    However, making a motor with a light coil can be done in several different ways. Some good, and some not so good. Among the not so good solutions are the use of an extremely short gap together with a short coil. This only gives a super low excursion, not very linear motor. Another not so good way is to use a pole piece and/or top plate with a split, and have the coil half way into both gaps. The problem here is that when the coil is situated in one gap, all the flux tend to move to the other gap. One way that do work is to make two magnetic circuits, one for each gap, and position the coil as described above. That way a 10mm winding height can result in an x-max of 6-7mm. One can also do a more complex version with two tiny coils, each measuring just 6mm, and both of them being half way into a 3mm gap with a 3mm space between This gives an incredible 10+mm x-max. One could also make an all magnet motor, but that is really far ahead of the vintage JBL drivers.

    I think a double coil version with two separate circuits and the coil half way into both is a perfect solution for this type of driver.

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