Found the diagram I was looking for...
http://www.audioheritage.org/vbullet...841#post171841
Note Ivica, the LF section for 2235H or 2245H.
Only with the 'Engineering Design Specification' sheet to go on; I would say the Sensitivity of the 2122H to be close to 92dB - I can't find a definite
figure for sensitivity for the 2122H anywhere. Going by the frequency plot - that's close enough for me. [To work off..]
DogBox
Last edited by DogBox; 11-01-2013 at 04:31 PM. Reason: Add link
In the small midrange box of a 4344/45 about 98db . It's really nice midrange driver.I can't find a definite figure for sensitivity for the 2122H anywhere.
http://www.lansingheritage.org/image...345/page04.jpg
Rob
"I could be arguing in my spare time"
Hi DogBox,Originally Posted by DogBox
I notice you put the 2202H into a 50 L. box. From the only formula I had on hand, you need to reduce that volume 'down' to about "half" that so that by using a smaller box, the driver will naturally "cut-off" at about 280Hz, still getting a bit as it tapers off - closed box @ 12dB/octave. So then, all that would be required is to tame the 2202 down to a proper level - without upsetting the apple-cart! And the "top-end" has been done already by
yourself and others in the forum...
Possible?...
DogBox
Yes I have given here a larger box for 2202H, as JBL have done on 4355/50 box, and a kind of passive (60uF, 4.8mH) or active hi-pass would mainly define drivers LF section response. In any case I will not 'overdrive' 2202H with full LF bandwidth , what would happen if no hi-pass network applied.
regards
ivica
I am thinking Hi-Pass is still needed for balance to 2441; however, Lo-Pass on 2202 can be omitted as a "smaller box" [my original calculations suggested 10L !! but the roll-off frequency was good!] will actually do it acoustically. Why put in electronics when there is no way of getting a response out of a speaker because it has no room to move air? maybe only security... See where I am coming from?
It has been noted that the 45L / 4350 & 48L / 4355 sub-chambers are of a size to be a Acoustic Suspension - the box is only a shielding from the Main LF Chamber. In the JBL Professional Enclosure Guide it suggests a 1.5 cu ft / 42.48 L box to be 'vented' with a 4.2 hole in the baffle!
Remember, we are dealing with - in this instance - a woofer that doubles as a good Instrument Speaker.... We have to change the role...
DogBox
In the small midrange box of a 4344/45 about 98db . It's really nice midrange driver.
http://www.lansingheritage.org/image...345/page04.jpg
RobThanks Rob! Didn't know they went into "that much" detail on the other drivers. I saw the Engineering Design Specification sheet p2. Frequency response and made an 'un-educated' guess at "what it might be..
But this figure is, as you say "when it is inside the midrange box"...
Does the sensitivity of a driver "go up" when put into a small sealed box? That could change lots of things in working out a network...? Does it???
Many Thanks!!!
DogBox
I wouldn't spend a lot of money on the supposed sonic differences between the alnico and ferrite 2405's.
"Audio is filled with dangerous amateurs." --- Tim de Paravicini
Hey SpeakerDave, I've just noticed I have become 'Senior' - now that's happened, I won't be able to tell "what" goes on up that high!
Do JBL do hearing aids?
If I couldn't get Alnico, it wasn't meant to be. I have four 2405 - all ferrite. Two came with dia's and two didn't. So I ended up getting a JBL set to go into one of the pairs. Lets me do up a set while listening to the other... Gotta have music to work to!
One thing on the "too hard" list was a set of 2405 perspex lenses! Now, do THEY make a 'sonic difference'... 'cause they sure look cool!!!
DogBox
Hi DogBox,I am thinking Hi-Pass is still needed for balance to 2441; however, Lo-Pass on 2202 can be omitted as a "smaller box" [my original calculations suggested 10L !! but the roll-off frequency was good!] will actually do it acoustically. Why put in electronics when there is no way of getting a response out of a speaker because it has no room to move air? maybe only security... See where I am coming from?
It has been noted that the 45L / 4350 & 48L / 4355 sub-chambers are of a size to be a Acoustic Suspension - the box is only a shielding from the Main LF Chamber. In the JBL Professional Enclosure Guide it suggests a 1.5 cu ft / 42.48 L box to be 'vented' with a 4.2 hole in the baffle!
Remember, we are dealing with - in this instance - a woofer that doubles as a good Instrument Speaker.... We have to change the role...
DogBox
I think that it would be not good to push the driver the signals that it can not to reproduce correctly. Under such circumstances a large amount of distortion can be generated, and the operating point of the VC can be offset-ed....so my suggestion is to use proper Hi-pass (say over 300Hz) either passive or active.
Regards
Ivica
Yes, Mr Widget!
And before this thread gets too 'one-tracked'... (I am as much to blame here)..but besides the commonly seen configurations coming off the "JBL" Drawing Board... Nothing wrong with these neither!
I have only partially explored the site and found 'some' of these and if it is a statement: What the People are after; AND, don't mind sitting "proud" in their living rooms!
Going through peoples 'Personal Systems' was a big eye opener in this regard. But all in the hope of "Having something a 'little different' that sounds really good too!" While configurations are many, some here on the forum "can just look-at-a-bunch-of-drivers" someone has gathered together in the hope of making something of them; and because of direct knowledge: be able to "tell straight away 'if' "it will" or "Wont Work"....
Wouldn't it be good to have those configurations: "down in writing?" so the prospective 'gatherer - builder' has a DEFINITE GUIDELINE, to stay within if
he/she is to have any sort of success...? These people are well-known and highly respected; their word trusted by their knowledge and experience.
I think this knowledge of these configurations would be good to see listed. And it would keep JBL - JBL!!!
DogBox
From my own experience, these midrange drivers don't seem to age gracegully. I've had a few break the voice coil wires where they attach to the terminal. It nearly borke my heart when my great sounding one-off aquaplassed diaphragms broke down. They lasted two or theree years. There is no litz, they just extended the voice coil wire all the way to the terminal, with an S bend that doesn't seem to help. So It is my theory that JBL dropped the series in favor of more reliable and long lasting designs. It was probably the right decision. The newer inverted ti dome drivers with conventional voice coils have not given me any trouble yet.I wonder how that would compare with the 4" dome from the XPL series, the 095Ti or 093Ti... a few folks here have played with them or the Auto Sound variant. The 2441 is aluminum and has a much more massive magnet... but they both use somewhat similar geometry.
I'm not sure why the XPL series was relatively short lived, by all accounts they were very fine speakers... but then the Westrex is a phantom of history too. One would think if either was the holy grail, there would be legions of similar speakers, even if manufacturing costs were prohibitive. No doubt both are great speakers, but why aren't there more like them?
Widget
Thanks again for that. If this 2202H doesn't work out, I may have to go back to my original plan of "original" 4343 with the 2121H.......It's really a nice midrange driver. (2122H)
http://www.lansingheritage.org/image...345/page04.jpg
Rob
I have heard about the 'cone break-up', but "How bad IS IT?" as you just can't swap in a 2122.. the phrase.."Won't work.." comes to mind...!
And when you look at the T/S figures you can see why! So, 'what does "cone break-up" sound like?' Isn't it "only" at high volume SPL's?
I have read it[2121] is the "best" speaker in the 4343, so how 'bad' is it?
On a different note but still with the 4343; apparently a CC Network wouldn't improve the 4343? I haven't "seen one by Giskard" so I am thinking that "all you can do to get the best out of it" is to "bias" the capacitors?
I was thinking of using a 2441 instead of the 2421 but I am not sure if that is proper? Has anyone done something like this ?
I dont want to be morphing anything, but for sound quality I was wondering ?
DogBox
Hi Ivica,
I have had some computer hassles and too many other things going on... I also managed to download a copy of PSPICE to do some modelling of my own and also in the process of getting a microphone to go with the test set-up i've built. Not as Hi-Tech as your programs [wow!] but I hope to manage!
I think you are right in your Hi-Pass theory for the midbass. The other network you posted [trial] looks good. I did think some others may chime in, however, I think we are on our own on this one. I was nearly tempted to get another pair of 2202h from ebay as you can't get recones anymore. So sad, especially for a driver such as this. And no aftermarket that I have seen either...
If I can't use the 2202, I may have to revert back to my original plan/build of the 4343 'stock'! But like I told Rob, the idea of having a 2" compression driver sounds a feasable idea.. I have all the stock parts, but..
Looking forward to getting some time to 'spice' up my life!
DogBox
Hello DogboxThanks again for that. If this 2202H doesn't work out, I may have to go back to my original plan of "original" 4343 with the 2121H...
I have heard about the 'cone break-up', but "How bad IS IT?" as you just can't swap in a 2122.. the phrase.."Won't work.." comes to mind...!
The problem with either the 2121 or 2122 is cone kits or just being lucky enough to find drivers in good condition. Worst case you could re-foam them. As far as the "cone break up" I wouldn't worry all that much about it. They incrementally improved the drivers from the 4341 up through the 4344. How loud are you going to play them, I bet you quit before they do. To swap out those mids you would need to change the crossovers. The best crossover of all was the 4344 and we have a solution that 4313B worked out years ago. My 4344's use his "equivalent" crossover and it's excellent.
Rob
"I could be arguing in my spare time"
Sorry for writing "in the middle of your quote - I haven't quite mastered my "thread techniques!Hello Dogbox
The problem with either the 2121 or 2122 is cone kits....They incrementally improved the drivers from the 4341 up through the 4344. How loud are you going to play them - I bet you quit before they do.[Exactly!] To swap out those mids you would need to change the crossovers.[Do you mean:"All-of-it?" OR, just that leg???] The best crossover of all was the 4344 and we have a solution that 4313B worked out years ago.[If I understand where you are going with this: CC Networks AKA Design Cut ?] My 4344's [I wanted to keep to 4343 "if" I can - even if I would like to have a 2" HF Section! It hides behind the lens,etc....!] use his "equivalent" crossover and it's excellent. [I know & I'm tempted - "IT hides in the box!!!]
Rob
I have "passed-up" some 2122 [even with only about 15 left] for the 2121 recones. Which makes me sort-of committed to 4343. [Still have the 2202H's..] I am not going to worry about cone break-up. But as far as the driver above it..I don't know. I have my mock 2420 to put in..
The crossover has had me going for ages, I simply don't know enough to make design changes myself. Or, to test out any theories I might have.
Which is why I am forced to go with the standard design by using the original drivers. That much I have learned.
It would be nice to experiment though!
Thanks for your help and input!
DogBox
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