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Ed Zeppeli
02-06-2014, 07:50 PM
I finally got a pair after having a few slip through my fingers. :D

These ones seem to be early vintage, however after opening them up not all is as expected.

I was told the drivers had been re-foamed and to me, that would explain the dust cap glue being less than uniform as it may have been removed for shimming.

https://fbcdn-sphotos-g-a.akamaihd.net/hphotos-ak-ash3/t1/1779736_10151846359791076_1784607521_n.jpg

...but after removing the drivers I see this on the backside...They are the same in both speakers.

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-ash3/t1/1779677_10151846359566076_1511965729_n.jpg

:blink: So, I'm wondering if it's possible that they did a whole re-cone and put the mass ring in there but I fear the only to find out would be to cut off the dust cap. Is this my only possibility? The speakers certainly sound good but having never heard 4430s before I have no reference for how the bottom end should sound.

Also, the 2344s are driven by these...

https://scontent-a-sea.xx.fbcdn.net/hphotos-prn2/t1/1497290_10151846359686076_1666593770_n.jpg

and the diaphragms look good but are they aluminum?

https://fbcdn-sphotos-f-a.akamaihd.net/hphotos-ak-prn1/t1/1654432_10151846376656076_1667457270_n.jpg


Notice below the two-piece 2344 and the (OEM?) support for the comp. driver. In another picture I've seen there is driver support internally via a wooden cradle. I wonder if this is also indicative of these being very early versions of the speakers.

Thanks for looking and I'd appreciate any insights.


Regards,

Warren

1audiohack
02-06-2014, 08:43 PM
I'm going to jump out on a limb and hope I don't get shot at.

I built a bunch of 2234's 2235's in 223X and E motor baskets, all at once, with real JBL 2234/5 kits all purchased at the same time from the same lot number and measured for real with Leap LMS with a VI box for constant voltage control like we really use them and found that the change in FS with and without the mass ring was less than 2Hz, and the change in Fs with the E motor was also less than 2Hz increase. The midband sensitivity was affected less than 2dB with the same changes.

Do they change? Yes. Substantially? I would say no. I get that they do things for real reasons but the refoam would likely change things that much or more. Since your baskets at least have the 2344 motors even with out the mass rings you won't be 2Hz or 2dB off. The amp (low impedance) and the port are strong forces, the resonant frequency is a week force and you have adjustability to comp for the increase in midband if the mass rings are not installed.

I have 4430's and 4435's so I am familiar with them and in my opinion, if I were you, I wouldn't waste one more minute fretting over this.

Hope that helps.
Barry.

Ed Zeppeli
02-07-2014, 07:35 PM
Thanks Barry. There is some reassurance to be taken from your experienced claim that there is very little difference between these drivers and I appreciate it.

As you know, much of the joy of this hobby is in the details and tweaking involved so I don't want to be caught wondering if it's that damn mass ring as I'm listening intensely. :)

Anyone care to offer insight on the diaphragms?


Cheers,

Warren

allen mueller
02-08-2014, 02:07 AM
The earlier 4430/4435's had the more desirable 2421 driver on the highs due to the aluminum diaphragm. If you poke around the early jbl literature on them I've seen 2421 driver in the specification as well. The switch to titanium/ferrite on the highs must have been early on since you don't see too many sets around with the 2421's.

Allen

Ed Zeppeli
02-08-2014, 05:06 AM
Yes I'm aware that this is the driver authentic to early 4430s, however I'm not sure if it's the driver or the aluminium diaphragm that made it desirable. :)

I realised that I forgot to add the photo of the 2421 support which I'll upload tonight.
Thanks

Mr. Widget
02-08-2014, 09:44 AM
I'm going to jump out on a limb and hope I don't get shot at.

I built a bunch of 2234's 2235's in 223X and E motor baskets, all at once, with real JBL 2234/5 kits all purchased at the same time from the same lot number and measured for real with Leap LMS with a VI box for constant voltage control like we really use them and found that the change in FS with and without the mass ring was less than 2Hz, and the change in Fs with the E motor was also less than 2Hz increase. The midband sensitivity was affected less than 2dB with the same changes.

Do they change? Yes. Substantially? I would say no. I get that they do things for real reasons but the refoam would likely change things that much or more. Since your baskets at least have the 2344 motors even with out the mass rings you won't be 2Hz or 2dB off. The amp (low impedance) and the port are strong forces, the resonant frequency is a week force and you have adjustability to comp for the increase in midband if the mass rings are not installed.

I have 4430's and 4435's so I am familiar with them and in my opinion, if I were you, I wouldn't waste one more minute fretting over this.

Hope that helps.
Barry.As for the E motor, I'd suggest 2dB is significant... on the mass ring no mass ring question, did you take your measurements after the cones were both well broken in? Not questioning, just asking the question. :)

Beyond the Fs question the mass ring will also affect the frequency response... here again a half dB of change over an octave or more is quite audible.

To satisfy the original poster, I wouldn't cut open the woofer, but I would want to verify the performance by careful measurement... find someone to help if necessary.

About the 2421 diaphragm... can't tell from the photo. The proper aluminum diaphragm should look like bright aluminum foil. The Ti 2425 diaphragm will be a slightly darker gray color.


Widget

grumpy
02-08-2014, 11:02 AM
The diaphragm -with- the driver is what makes it "more desirable" from an authenticity/collector POV.
The diaphragm by itself (I would argue) makes the larger audible difference.
Not clear that the dia in the pic is aluminum ... looks more titanium-ish as the sheen
is very non-directional, almost metallic eggshell looking (look at the bottom of a soda can...
you can see something that looks like a directional "brushed" pattern if you look closely.
Difficult to capture in a photo... a side-by-side will help you learn to identify them.

Re 2234 vs 2235. I also tried and measured them both in 4430s. The measured difference was
primarily one of sensitivity over the main response bandwidth... approaching 2dB. If you biamp,
the difference is moot. If not, adjusting the L-pads a bit can help return the main voicing.
Noticing the difference in low end was very material dependent (most made little difference).

If the cabinets are in great shape, it's probably worth sorting out the correct parts... this stuff
seems to be increasing in value, and originality often wins. I could have left the 2234s in there
and been happy (in mine), but I had the 2235s, so they eventually went back in.

Ed Zeppeli
02-08-2014, 06:35 PM
Thanks for the feedback re: 2234 vs. 2235 gents. I have some food for thought here, especially on what measurements would best indicate if there was indeed a mass ring. Since I'll be using these with my recently built 2242 sub I'm not overly concerned with any lack of bottom end; more interested in a genuine authentic sample of the 4430.



Here is the picture of the comp driver support bracket for the early model. The holes at the end of the bend on the plate attach via bolts to a front-to-back internal support brace.

https://scontent-b-sea.xx.fbcdn.net/hphotos-ash4/t1/995841_10151846376696076_921102099_n.jpg


Cheers,

Warren

1audiohack
02-08-2014, 08:55 PM
As for the E motor, I'd suggest 2dB is significant... on the mass ring no mass ring question, did you take your measurements after the cones were both well broken in? Not questioning, just asking the question. :)

Beyond the Fs question the mass ring will also affect the frequency response... here again a half dB of change over an octave or more is quite audible. Widget

Valid questions indeed but I must confess that I don't think that I (just meaning me) would hear .5 dB. Two dB yes.

I don't typically artificially age my drivers but for this experiment I ran them free air with no dust caps or mass rings at 10Hz for 48 hours, four at a time at about 0.200" cone travel, I don't recall the voltage though. I built eight, four with E motors and four with 2235 motors. I am going to look on the old hard drive to see if I still have all the experimental data.

I believe anyone would have every right to question the validity of this experiment but here's the short story. I built one sealed test box and four identical vented boxes for listening as well as measuring. The vented boxes were 5CFt corner vented which allowed for changing the vent length without removing the drivers or moving the boxes. I tried really hard to make a set up that didn't have to be disturbed to mod the box tuning or to add the mass rings.

In addition to two high quality calibrated measurement mic's and two, two channel FFT meters, I also used our laser position sensor to monitor the cone motion and phase against the electrical signals via a four channel oscilloscope. Looking, like really looking, being able to see the cone excursion and timing as compared to the stimulus signal from the amp, and the electrical signals from the mic in the port and the mic in close proximity to the cone, all at the same time was VERY educational. I spent a couple of weeks after hours measuring and listening to this mess. I used for the top 2344/2426's for listening. As for what is still in MY 4430's? E motors with mass rings. Why? I liked them best.

I don't want to derail this thread but have likely done it already. Sorry.

Oh yeah, 100% with the Dude. :)

Barry.

Ed Zeppeli
03-01-2014, 07:53 AM
So I finally had a chance to get these into position at home and do a little maintenance.

Unfortunately the two mid-control pots are reading dead spots almost through the entire range. I haven't removed them yet as I wanted to listen to these speakers a while before completely dismantling them.

I searched exhaustively through the forums and found a few dead links to parts-express for some 100 watt replacement pots. I'd like to order four new pots for both speakers but am not too eager to take these apart (and leave them apart) until they arrive.

Can anyone give me a heads up on which ones to order, specifically, so that I might be able to replace them all at once when they arrive?

Thanks in advance!

Warren

remusr
03-03-2014, 01:33 AM
Probably dirty - have you tried to rotate them many times back and forth? contact cleaner along shafts? Maybe have to take them out to access. Common problem with L-Pads that do not get moved much at all.

Ed Zeppeli
03-03-2014, 05:40 AM
Yes. I sprayed them as best as I could with CRC and rotated them back and forth. It may be worth checking them out again when I have them out but at that point, why not just upgrade them?

Thanks

christo
03-03-2014, 01:39 PM
So I finally had a chance to get these into position at home and do a little maintenance.

I searched exhaustively through the forums and found a few dead links to parts-express for some 100 watt replacement pots. I'd like to order four new pots for both speakers but am not too eager to take these apart (and leave them apart) until they arrive.

Warren

Not sure if you got a response, I got my pots at Solen http://solen.ca/pub/index.php?s1=1

Chris

Ed Zeppeli
03-03-2014, 01:45 PM
Thanks. Which ones did you order? I understand that the treble pot is a rheostat?

Earl K
03-03-2014, 02:37 PM
Something like the following could work ( if the shaft length matches your needs ) ;

Click the pic ;

https://solen.ca/photos/pics/lp50w.jpg (https://solen.ca/pub/index.php?catalog=description&nodiapo&id=1515&recherche=&numRows=&manufacturiers=&niveau1=1&niveau2=5&niveau3=36&s1=2&s2=5&s3=&s4=)

:)

Ed Zeppeli
03-03-2014, 03:40 PM
Thank you Torontonians!

That's the big question really. What length shaft do I need on the l-pad? The price seems reasonable enough that it's worth a gamble though.


Warren

christo
03-03-2014, 07:15 PM
Thank you Torontonians!

That's the big question really. What length shaft do I need on the l-pad? The price seems reasonable enough that it's worth a gamble though.


Warren

It all depends upon the thickness of the baffle, but in your case as it is a finished cabinet I would take the existing LPAD out and measure the length of the post. I believe the length is the threaded part of the shaft and does not include the end and which the plastic knob inserts on, but I could be wrong.