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Thread: J's & H's and Compression Drivers & More

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    J's & H's and Compression Drivers & More

    A few random questions.

    I am trying to gather drivers together for a speaker project. It will probably use two woofers per side. The one woofer I have is an "H" - 8 ohm - and there is also a "J" version - 16 ohm. I'd rather have all J's but it seems to rather a rare woofer - at least they're rare on Ebay - and I may not be able to find all of one version. But maybe I can find two of each. Anyone mix H and J versions together? One H and one J in each speaker. I don't expect this is a problem, so long as the amplifier is stable in the load, but maybe I'm missing something.

    I'm new to horns. They're a bit of a mystery to me, but I'm picking up bits and pieces. The horn I'll probably use is the JBL 2382A, but what compression driver is best? I know the 2450 and 2446 series will work, and I'll likely find the 2446 cheaper. How about the more common 2445 series? What is better about the 2446 over the 2445? I know there are some older drivers that will fit, according to the spec sheet, but I'm a bit leery about them.

    Several places have mentioned horn equalization. Does anyone use it, how do you do it, and how will I know what the correct equalization is? Is this a subjective thing or is there a standard for each horn?

    Thanks!

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    RIP 2011 Zilch's Avatar
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    What woofers are you talking about?

    Run an 8 and a 16 in parallel, and the 8's gonna get 2/3 of the total power, no?

    That is if they actually ARE 8 vs. 16 ohms.

    Clone a stock design....

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    Quote Originally Posted by Zilch View Post
    What woofers are you talking about?

    Run an 8 and a 16 in parallel, and the 8's gonna get 2/3 of the total power, no?

    That is if they actually ARE 8 vs. 16 ohms.

    Clone a stock design....
    If you put them in series and dropped just the right value resister across the 16 you could give them equal power except that the value would be a moving target plus it's probably too wierd.

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    Quote Originally Posted by BigT View Post
    A few random questions.

    I am trying to gather drivers together for a speaker project. It will probably use two woofers per side. The one woofer I have is an "H" - 8 ohm - and there is also a "J" version - 16 ohm. ...

    I know there are some older drivers that will fit, according to the spec sheet, but I'm a bit leery about them.

    Several places have mentioned horn equalization. Does anyone use it, how do you do it, and how will I know what the correct equalization is? Is this a subjective thing or is there a standard for each horn?

    Thanks!
    Recone one of them. It's just not going to work well for you to mix 8 and 16 ohms, especially trying to get equal output. Although, I suppose you could run them across different frequencies. For example, use a cascade type crossover, ala 4435. Run the 16 ohm across a wide range, tune the cabinet very low so you get an extended bass shelf, then run the 8 ohm driver in parallel with the 16 ohm but with a 12mH coil in series with the 8 ohm driver. This will fill up the low end but may still have a bump there because the 8 ohm driver will be louder. Just something to think about.

    Old compression drivers can be very nice but you need to fill in the top end with a 2405 or something. Also, don't over power the old ones

    EQ'ing horns is all about getting rid of the honk, a broad bandreject. This also helps pad it down to match your woofer but you still will need a little more padding. Then if your using a CD type horn you may need to keep the higher frequencies hotter because your spreading them all around the room. The net effect is that the CD horn won't seem as bright. All of these EQ filters interact with each other especially if done passively, so you need to get an idea of what your response looks like and then decide how best to cut the hot areas down to give you the widest, flatest response. Good luck.

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    I've done this in what we would call a 2-1/2 way I suppose. Used the 8 ohm woofer normally and took the 16 ohm woofer and a big choke in series and made it the helper woofer. The 16 ohm of course had much lower output... but that was just what was desired. Helper woofer only covered the range from Fs - 200 Hz.

    Cyclotronguy

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    Looks like I won't be running unmatched woofers. I don't need any extra complexity right now. It's ok - I've got plenty of time to find what I need.

    The woofer is the 2220H - it seems to be the most efficient woofer I can find. Is the 2220A basically the same thing?

    I will very likely be using an active crossover. Anyone use an active crossover for horn equalization? Which crossover was it? The horn is a 2382A - does this one need much equalization? Don't know which compression driver yet.

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    RIP 2011 Zilch's Avatar
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    Indeed, it appears there are different impedance versions of 2220, from the Transducer Parts List:

    2220A = 8 Ohms
    2220B = 16 Ohms
    2220C = 16 Ohms

    2220H = 8 Ohms
    2220J = 16 Ohms

    A, B, and C are Alnico, I would assume, H and J having ferrite magnets. The difference between B and C may be known to others, or discussed somewhere in the forums.

    Review the datasheet for the 2382A horn. It's constant directivity, and will therefore require compensation. Does the CD EQ built into any available active crossover match what is required? Not in detail, probably, though you may get lucky and come close.

    Regarding the compression driver question, 2446 adds coherent wave phase plug, as I recall. Look this stuff up on the factory datasheets to be sure....

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    Dang. Amateur speakerdave's Avatar
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    Possibly the 2220C was a JBL Pro counterpart for the 130B, a "32 ohm" job that may have been hatched in the same flex-ohm strategy that was the source of many JBL 16 ohm drivers. The 130B crop up only occasionally on ebay and go for high prices. (Or maybe JBL feels no one really needs a 32 ohm driver any more.) I have some 2220B's on hand. The DCR shows they are truly 16 ohm drivers.

    David

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    Quote Originally Posted by BigT View Post
    Looks like I won't be running unmatched woofters. I don't need any extra complexity right now. It's ok - I've got plenty of time to find what I need.

    The woofer is the 2220H - it seems to be the most efficient woofer I can find. Is the 2220A basically the same thing?

    I will very likely be using an active crossover. Anyone use an active crossover for horn equalization? Which crossover was it? The horn is a 2382A - does this one need much equalization? Don't know which compression driver yet.
    I'm sorry, but the 2220 is a poor woofer for normal enclosures. The only place that I have found that they work well in is a horn loaded situation like a klipsch corner horn. The Q is so low that they just don't have any bass in a closed or vented cabinet. You can get a lot out of it for 100Hz up, but nothing to speak of below that.

    Eric

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    Quote Originally Posted by blackwell View Post
    I'm sorry, but the 2220 is a poor woofer for normal enclosures. The only place that I have found that they work well in is a horn loaded situation like a klipsch corner horn. The Q is so low that they just don't have any bass in a closed or vented cabinet. You can get a lot out of it for 100Hz up, but nothing to speak of below that.

    Eric
    Yes, I quite understand that the 2220 is not intended for low bass. Part 2 of my project will be subwoofers. My goal for Part 1 is efficency. I once owned Klipschorns in the mid-70's but sold them when I came under the influence of those "underground" rags. Once in a while I get nostalgic for the easy dynamics and sharpness that was Klipsch, and this is one of those times. This is the first time I've actually invested in drivers to do something about it, though. I no longer want Klipschorns; I have a tough time with that midrange horn going down to 400Hz and the woofer section doesn't go low enough for these modern times, although in their day, when vinyl was king, they went low enough.

  11. #11
    Maron Horonzakz
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    The 2220C,,,130B 32ohm was used in a double scoop horn... I have a pair both have the same serial number. I dont know how mutch they are worth.

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    Quote Originally Posted by Maron Horonzakz View Post
    The 2220C,,,130B 32ohm was used in a double scoop horn... I have a pair both have the same serial number. I dont know how mutch they are worth.
    It would be interesting to have a DCR reading on them.

    David

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    Quote Originally Posted by BigT View Post
    Yes, I quite understand that the 2220 is not intended for low bass. Part 2 of my project will be subwoofers. My goal for Part 1 is efficency. I once owned Klipschorns in the mid-70's but sold them when I came under the influence of those "underground" rags. Once in a while I get nostalgic for the easy dynamics and sharpness that was Klipsch, and this is one of those times. This is the first time I've actually invested in drivers to do something about it, though. I no longer want Klipschorns; I have a tough time with that midrange horn going down to 400Hz and the woofer section doesn't go low enough for these modern times, although in their day, when vinyl was king, they went low enough.
    This is an interesting project to me. I think those early speakers with the woofer that went up to 1000 or 1200 Hz were not done because Lansing could not think of anything else to do. The Iconic and other speakers with an 800 cycle crossover pre-existed them. The high first crossover is also one factor that makes the 604 sound so good, although 1500 is too high for that cone. I mean there is a real advantage in not having a crossover in the voice fundamental range. To increase the bass two-woofer configurations are a possibility--the double scoop, the JBL C1000, the Altec 820--but I think you get into a problem with two sources that will not couple acoustically through their entire frequency range. I'm not sure at what frequency you get into that problem with two fifteens, but I think it is below 1000 Hz.

    You are probably aware that Drew Daniels used a 2220 from 80 to 300 Hz in the first version of his Ancient Audiophile system, and the 2227 later. I'd like to see a 12 or 14 inch driver that would do well from 50 (or a little higher, but not much) to 1000 or a little higher and be efficient enough to work to a horn, and preferably do this in a sealed enclosure. The JBL 2217 is a tantalizing prospect, but it has suckout in the middle of that range that I think would be difficult to deal with without digital correction. The Altec 414 might work, but I just have not gotten around to trying it. The JBL 1400nd actually does this quite well, and with two of them per side the bass is also very good, but it is hard to get hold of that driver.

    Meanwhile these JBL 130A's and 2220's offer a kind of nostalgic look at the possibilities. Not the most accurate driver, but certainly lively and provides that seamless run through the voice range.

    David

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    Quote Originally Posted by speakerdave View Post
    Meanwhile these JBL 130A's and 2220's offer a kind of nostalgic look at the possibilities. Not the most accurate driver, but certainly lively and provides that seamless run through the voice range.

    David
    Agreed. The vocals (especially male) were much better (more intelligible and natural) using my 130As over the 2205s reconed as 2235s. But..., bass response was lacking.

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    My measured specs on a pair of 2220B's!

    Quote Originally Posted by speakerdave View Post
    Possibly the 2220C was a JBL Pro counterpart for the 130B, a "32 ohm" job that may have been hatched in the same flex-ohm strategy that was the source of many JBL 16 ohm drivers. The 130B crop up only occasionally on ebay and go for high prices. (Or maybe JBL feels no one really needs a 32 ohm driver any more.) I have some 2220B's on hand. The DCR shows they are truly 16 ohm drivers.

    David
    Revc 8 ohms - - - 8.1 ohms
    fs 40.8 hz - - - - 41 hz
    Qes .44 - - - -- - .34
    Qms 2.55 - - - -- 2.37
    Qts .377 - - -- -- .3
    Zmax 54.7 ohms - - -63 ohms
    Le .87 mh- - -- - .94 mh
    Vas 9 cu ft -- - - -8.89 cu ft
    BL 18 - - - - - -- -20.6
    Sens 97.8 db- - - - 98.8 db
    Eff 3.8 %- -- - - - 4.8 %
    RMS 7 ohms - - - -7.7 ohms (mechanical)

    Results taken from WT2 in my living room with less than ideal conditions.

    The cones were not perfect and show signs of light abuse(dented cone indentations like a slipped screwdriver), but no major damage. These units are borrowed and I might keep them for the long haul for my 100 hz straight horn (Dr Bruce Edgar built).

    I'm not sure the impedance of "my" units can be thought of as 16 ohm drivers. The impedance dances closer to 10 ohms for much of the testing I did.

    Just thought I would share my results with you all!

    Regards, Ron
    JBL Pro for home use!

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