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View Full Version : What is the problem with this 2235h driver [video]?



DingDing
08-18-2014, 10:17 AM
Hi,
I bought this 2235h driver knowing it might need a recone job, and I want to troubleshoot and try to fix it myself in hopes of learning something new. If it all goes belly up, it'll be reconed by a professional.

Made this video in hopes you guys could help me pin down if it has to be reconed or if I might be able to fix it myself. I think it sounds like the voice coil is rubbing, but having no experience with driver repairs I'm not sure. In the video I'm running a couple of sine wave test tones to induce the distorting sound. Please turn the volume up a bit, and the audio doesn't start right away, so be a little patient, please. :)


http://www.youtube.com/watch?v=QgAjVl3761s

What do you guys think? Is the cone misaligned? Do you want me to make videos from other angles? If the cone is misaligned, I thought about getting new foam surround, dustcap and spider and try to realign it using a shim. Do you guys think that would be feasible?

Also, looking at the pictures, do you think this looks like a genuine 2235h cone? It doesn't have any white chalk markings at the rear of the cone.

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grumpy
08-18-2014, 11:17 AM
I can't determine it. Someone else may have a keener eye and more experience.

If the cone is original, it probably has been refoamed (replaced surrounds) not reconed
with a JBL kit. Those mounting gaskets scream aftermarket.

macaroonie
08-18-2014, 11:24 AM
Gaskets are wrong for sure. Check to see if the spider is glued on properly , coil rub is more scratchy sounding. It would be better if you could run that at a lower frequency and not film it from the edge of the frame but straight on to the cone instead.

Try running it at 25 and 30 Hz.

A pic of the back of the cone would be handy.

M

DingDing
08-18-2014, 11:50 AM
grumpy: Thanks, I checked the mounting gaskets against my four other 2235h, and you're right they don't look anything like the originals. The spider looks to be very dirty (fine black dust), and when I placed my finger inside the pole vent in a 90 degree angle there was a lot of dirt buildup around the gap, so it has probably just been refoamed and something has gone wrong when aligning. Hopefully it'll be possible to realign.

Any ideas where I can get what I need to realign the cone? Hope the VC has only been misaligned and not bent into an oval shape. The basket looks to be round by my crude measurements.

DingDing
08-18-2014, 11:50 AM
Gaskets are wrong for sure. Check to see if the spider is glued on properly , coil rub is more scratchy sounding. It would be better if you could run that at a lower frequency and not film it from the edge of the frame but straight on to the cone instead.

Try running it at 25 and 30 Hz.

A pic of the back of the cone would be handy.

M

Hi, thanks. Yes I'll do that right now.

DingDing
08-18-2014, 01:30 PM
This took a little longer because it was hard to get proper lighting now that the Sun has gone down. Youtube also did no service to me by spending a ton of time compressing. I tried different frequencies, and as I was recording at 24 fps different frequencies gave different perceived slow motion effects. The distorting sound is evident throughout the frequencies tested and it seems to be following the frequency played, but doesn't get worse with higher excursion it seems. My unexperienced eyes can't see anything loose. I also did a lot of looking besides making these videos.

I'm turning it around etc late in the video above.


http://www.youtube.com/watch?v=Y7OO0KI20s8


http://www.youtube.com/watch?v=v7mBo9txLoo

I hope these are of any help, and I've got no problem making new videos from other perspectives. The videos will live long after the problem is solved for anyone else who might run across the same issue in the future.

Here are some images. There is no white writing or marks on the rear of the cone itself.

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martin2395
08-18-2014, 01:38 PM
I think it's one of those shitty China recones! I had a pair once, they only had a small production code in white stamped on the cone but otherwise they lacked the JBL service sticker and neither had the "2235H" marking done with chalk/white marker.
Also they even lacked the mass ring and sounded totally rubbish. The foam suspension was waaay too stiff and one of them was making popping noises due to poor soldering of the VC wires.

When I look at the VC wires next to the dustcap, they look like soldered and laquered by hand, with genuine JBL kit that part is already assembled.
I'm almost sure you also have that knockoff recone, take a look at the fakes (especially the VC wires)
https://lh6.googleusercontent.com/-_AoV8OC7QZI/UfUGPZq_uXI/AAAAAAAABLU/Qnh9HyAsFZM/w630-h840-no/IMG_1477.JPG

macaroonie
08-18-2014, 01:53 PM
My feeling is it is not coil rub but as you mentionthere seems to be residue in the coil area , could be disintegrated foam that found its way in through the vent or alternatively wasn't there a foam ' filter' plug in the vent. Just checked with mine , same driver and indeed therewas a foam filter on the face of the pole piece. Mine is now dust also but the drivers are not making any funny noises.
The solurion maybe is to put the driver face down and play it with your tone for a while and see if gravity helps this stuff to dislodge. It will fall into the back of the dust capand thenyou can vacuum it out through the vent.
Have you tried manually moving the cone and trying to hear any sounds of scraping ?.

martin2395
08-18-2014, 01:56 PM
I had that issue with 2214H's, not the easiest task to remove all that goo from the woofer but I was lucky.

Though if it turns out to be a bogus recone I wouldn't even bother, just rip it apart and put a nice fresh JBL 2235H cone in it.

macaroonie
08-18-2014, 02:18 PM
Note to self : Get the hoover out and get that c**p out of my woofers.

DingDing
08-18-2014, 02:40 PM
Thanks to all of you for the advice and insights.

If it turns out to be a knockoff I still want to try to fix it for the learning process, but even if it's fixed the cone will be ripped and replaced with a genuine one. Will look for small markings on the rear, but haven't seen any. I thought it was weird that the spider was so dirty, it looks like it has been a long time since the cone went in, but the surround seems so fresh. Also, all my other 2235h cones have white markings on the rear.

What I'm going to do is to first check the foam surround like SEAWOLF97 says. If that doesn't work I'll lay it upside down playing a low frequency to see if I can get any dirt out of the gap that way like macaroonie suggested. If nothing works, I guess I can gently cut it out and further try to verify if it's a genuine cone or not?

I'll measure the VC impedance now. I guess it should be 8 Ohm, right?

DingDing
08-18-2014, 02:44 PM
Note to self : Get the hoover out and get that c**p out of my woofers.

Yup, I laid it on the spinning IKEA pizza table, put my finger inside with a 90 degree angle, then rolled it around to get the dirt into the dust cap, then I vacuumed it out very gently. The noise was there before this though. I bought it knowing about the noise and got it fairly cheap. Like 80 bucks (which is cheap for a 2235h here in NO).

grumpy
08-18-2014, 02:44 PM
6 ohms.

http://www.jblpro.com/pages/components/2235h.htm

DingDing
08-18-2014, 03:03 PM
6 ohms.

http://www.jblpro.com/pages/components/2235h.htm

Thank you. Got 7.5 Ohms, but when I measured the leads by placing the probes of my cheap multimeter together they have 1.5 Ohms so subtracting I land at 6 Ohms.

martin2395
08-18-2014, 03:09 PM
FYI my geniune 2235H's measure around 6.4Ohms.

macaroonie
08-18-2014, 03:12 PM
Yup, I laid it on the spinning IKEA pizza table, put my finger inside with a 90 degree angle, then rolled it around to get the dirt into the dust cap, then I vacuumed it out very gently. The noise was there before this though. I bought it knowing about the noise and got it fairly cheap. Like 80 bucks (which is cheap for a 2235h here in NO).

Good , but remember that you are only getting the stuff that is on the face of the pole piece.
If you think about it if a driver is installed in a speaker typically it stays in the vertical position for years. Imagine that this foam crud starts to fall to bits , it will drop down to the lowest place it can , ie. the part of the VC that is lowest , and of course it will work its way into the gap at that point.

I have encountered this before with a non molested driver. The junk is on the inside of the VC and can only go one of two ways , forwards or backwards. If it goes backwards it will fall into the cavity at the back and do little harm.
Anyway here is my ad hoc method that has worked for me on a few occasions.
With the speaker on its back hold the cone with each thumb and index finger ( at 180 deg on the cone ) and move the cone in and out. Work your way around 45 deg at a time till you get your noise. Then you deliberately offset / tilt the cone to make the noise worse and work the cone back and forth for 6-10 times then relax the cone and move up and down without any deliberate tilt. If it gets better bit not completely gone then do it again. till it's OK.
You can be quite rough with these cones , think about what they do when they are working for a living.

DingDing
08-18-2014, 05:57 PM
macaroonie

I did as you say, and there is something that seems to be a metallic rubbing sound, so I guess the cone is misaligned. Tried to adjust it with your method, but to no avail.

I guess the next step is to get new surrounds and try to align it, then measure the frequency response and compare it to one of my other drivers to determine if this is a genuine cone or not.

Found this video, must be my lucky day. :D


http://www.youtube.com/watch?v=2WH6njycM2k

Any advice on supplier for dustcap, shim(?), glue, surround and mounting gaskets?

Odd
08-19-2014, 12:27 AM
Surround kit. Contact Rick C. [email protected]
He is looneytune2001 (http://www.ebay.com/usr/looneytune2001?_trksid=p2047675.l2559) on eBay

DingDing
08-19-2014, 09:48 AM
Thank you Odd. Will contact him for supplies. Hopefully it's not a cheap knockoff cone. Even though Martin is pretty sure it is, I'm still hoping that the extremely dirty spider indicates an original cone that has been refoamed poorly.

Made this video just now. This has got to be the VC rubbing, right?


http://www.youtube.com/watch?v=v1HlAXLIhqA

Since pushing it into place is a no go, I guess I can remove the dustcap and surrounds just to do further inspections if this is a genuine cone or not? Anything in particular I should be looking for? Can upload videos and pictures for future reference of course.

grumpy
08-19-2014, 10:03 AM
check the pictures in this thread:

http://www.audioheritage.org/vbulletin/showthread.php?31325-2225-2235h-conversion-question

SEAWOLF97
08-19-2014, 10:21 AM
This has got to be the VC rubbing, right?

IMHO , I think that the surround is not centered. Cut it out, so that it's NOT misaligning the top of the cone and retry to see if any more rubbing. At this point, nothing to lose by doing so.

If no more rub, then easy , install another surround, carefully.

If it still rubs, then new cone time.

DingDing
08-19-2014, 11:13 AM
check the pictures in this thread:

http://www.audioheritage.org/vbulletin/showthread.php?31325-2225-2235h-conversion-question

Thank you.


IMHO , I think that the surround is not centered. Cut it out, so that it's NOT misaligning the top of the cone and retry to see if any more rubbing. At this point, nothing to lose by doing so.

If no more rub, then easy , install another surround, carefully.

If it still rubs, then new cone time.

Thank you, and I think you're right, because I removed the dustcap to see if there was a mass ring underneath (if not, it would surely not be a genuine cone). Luckily there was one there, but it's black and not silver/metal colored like I see in google images.

When I look closely at the VC, it looks to be misaligned. We see some markings on the inside in this video, and I'm nut sure if they are scratches or just goo from the foam infront of the pole vent, but it absolutely rubs at one point.


http://www.youtube.com/watch?v=f1hY9loO1Bw

Sorry about the intense breathing, I get that way when I'm focused and have a cold, lol. :D The sounds around 15 seconds is just the table, and not the driver.

I'm going to use a shim to set the surround anyways, and also going to clean out any dirt I'm able to get rid of, hence why I removed the dustcap.

DingDing
08-19-2014, 11:35 AM
The mass ring of the 2235h driver in the earlier posted video tutorial of the chap who does the refoaming is also dark grey or black, so I guess it indicates that the current cone is genuine. :bouncy:

Time to see if it's possible to cut off the surround and have it centered without any rubbing, then buy supplies and test my surgical skills.

DingDing
08-19-2014, 02:31 PM
The surround has been removed. Is it safe to play a test tone at 10 or 25-30 Hz to see if it self centers through the spider?

If it isn't the spider will be removed to check if the VC is dented into an elliptical shape, in which case I will recone it.

macaroonie
08-19-2014, 03:26 PM
Yeah just run it like that gently , cone facing up. Perhaps use a few tabs of electrical tape to stop the cone from tipping , ersatz surround.

DingDing
08-19-2014, 05:01 PM
Thanks again, I could not have done this without your help.

When the surround was removed I noticed the old surround was not completely removed from the frame, but I cleaned it up real nicely now. I also removed the inner glue where the foam piece preventing dust into the pole vent was.

As can be seen in this video the cone seems to be misaligned around the leads of the VC. (PS: The cone is not wobbling, it's an artifact of progressive video recording at 24fps, when the cone stops it's playing @ 24 Hz, hence the cam only see the same position 24 times a second).

NOTE: The volume in this vid is a little loud.


http://www.youtube.com/watch?v=9mjqndgCTEc

The loud metallic noise @ 1:15 is not the driver, but the heatsink on my amp, lol.

It's not easy to see that the VC is not centered properly in the video because of the shadows, but it's visible with the naked eye. I guess the spider will not self center the cone which is weird as the spider looks very old. Also, I don't believe the VC is dented, as it would rub in two places, not one if it were elliptical. Do you guys agree?

So here are some (crazy) ideas:
(1) The noise is not as evident when I play low frequencies, at 125 Hz like in the beginning of this video it's clear as daylight. If the cone was misaligned due to the refoam job that has been done and the spider has been there all along but been bent out of center due to the foam, then I could let it sit for 1-24 hours and play a tone in hopes the spider would realign the VC back into place.

(2) Gently use a heat gun on the spider and try to re-liquify the glue in hopes of realigning the VC back into center position.

(3) Tare away the spider, rip out the cone, measure the diameter of the VC to make sure it's not dented. Cross fingers it's genuine and reassemble. :D

macaroonie
08-20-2014, 01:03 AM
Spiders can sag , think of a driver sitting in the same position for 30 years , gravity has an effect.

DingDing
08-20-2014, 06:34 AM
Spiders can sag , think of a driver sitting in the same position for 30 years , gravity has an effect.

Ok, then I guess it's recone time unless some of the ideas work out. I think I want to try to do the recone myself, not to save money, but to gain some experience.

Not sure how to ask this properly, but are the original 2235h recone kits partly assembled like this?

http://i.imgur.com/WG9QvSh.png

If this is correct, it looks like I only have to clean out the old frame, solder the leads, glue the spider and surround, then gaskets and dust cap, right? With a kit like this where the spider is pre installed it doesn't look that hard to get the VC set at the proper depth into the gap.

Also, do original recone kits come with all the glue needed to do the job? I know a place where I can get genuine recone kits.

DingDing
08-20-2014, 07:42 PM
Ladies and gentlemen, the cone is out and there is no turning back.


http://www.youtube.com/watch?v=mjXLtiFxxic

Do you guys think this is the genuine article?

When measuring the voice coil, should I measure the windings only?

According to spec, VC winding depth is 191 mm (3/4 in), so I guess that is the windings only?

Sorry about the silly questions.

ivica
08-21-2014, 12:32 AM
Ladies and gentlemen, the cone is out and there is no turning back.


Do you guys think this is the genuine article?

When measuring the voice coil, should I measure the windings only?

According to spec, VC winding depth is 191 mm (3/4 in), so I guess that is the windings only?

Sorry about the silly questions.
HI DingDing,

1.
It seems to me that the coil and the sider are original,
2.
unfortunately You have cut the spider so, I think that it would be very difficult, (may be impossible) to remove it and put the new one without the VC destruction. As I remembered ther was a kind of suggestion to carefully remove the spider (without its destruction).
3.
You have to check is the VC almost perfect circular in order to be placed in the gap.

regards
ivica

DingDing
08-21-2014, 01:10 AM
HI DingDing,

1.
It seems to me that the coil and the sider are original,
2.
unfortunately You have cut the spider so, I think that it would be very difficult, (may be impossible) to remove it and put the new one without the VC destruction. As I remembered ther was a kind of suggestion to carefully remove the spider (without its destruction).
3.
You have to check is the VC almost perfect circular in order to be placed in the gap.

regards
ivica

Hi again, ivica and thank you for responding.

1. Yes, I measured the VC and it looks to be genuine

2. Haha, yes, unfortunately it was impossible to center the cone with this spider as it seemed to have sagged after 31 years, I'm going to start turning my 2235h 180 degrees around every 4 months or so from now on. In an attempt at removing the spider, I will try to use a heated surgical scalpel and gently, gently, gently try to cut away the spider to have it replaced.

When, not if, everything goes pear shaped I have also secured a brand new genuine recone kit I'm going to attempt at installing, should be interesting :D

3. Yes, I've done that and the VC seems perfectly circular, so it was probably a sagged spider as there were no large pieces of dirt in the gap.

martin2395
08-21-2014, 12:17 PM
I can't believe that's it's original unless it was butchered by someone, those VC leads just scream aftermarket.

DingDing
08-21-2014, 12:32 PM
I can't believe that's it's original unless it was butchered by someone, those VC leads just scream aftermarket.

Yeah, weird. Maybe someone had a bad day at the factory back in 1st of February 1983? :D

The basket had absolutely no marks which indicates that the driver has been reconed. If a driver is reconed, there will most likely be marks after the old glue from the spider is removed from the frame and there was no marks anywhere but on the top frame below the foam, so I'm pretty sure that the cone and VC is the original from back when the frame was made.

Maybe the tensil leads broke at one point and someone redid them? I've got no idea, but this has been a very interesting and fun experience.

I've cleaned out the frame and are going to attempt at saving the VC tonight.

Eaulive
08-26-2014, 12:00 PM
Unless I am mistaken, the 2235 does not have an aluminum former, more like an almost transparent reddish plastic/bakelite... much like the 2225


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And they don't have that black glue aroud the VC either, and the VC does not protrude so much from the cone, it's glued from underneath with a harder, breakier glue that is light in colour.


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