Tired 2205A ?

[Earl K]

Hi Ken,

Fitting a new cloth m-roll surround is typically a losing proposition.

- As a professional reconer , what leads you to make that statement ?

- Is it the cost of all the additional prep-time needed ( like neatly cutting out the old surround ) to get a nice-fitting, good-looking result ( ie; this approach being labor intensive & therefore reflected in the final price ) versus the known cost & time of a straight recone in a cleaned up basket ?

- I have a few surplus 2225s and am mulling over installing some of Rick Cobbs foamed surrounds to create a lowered Fs , short coil hybrid . Hence my interest in your answer .

I'd rather do these fixes on an injured, working JBL cone assembly than waste my money on an aftermarket cone kit with the wrong electrical and dimensional properties...the voice coil is the heart and soul of JBL drivers, and wrong ones just sound wrong.

- I certainly agree wth that, if one installs aftermarket kits then a person will have no idea if the voice-coil is wound with the proper gauge of wire and whether or not the proper length in the winding has been achieved.

If you've got cracks in the 2205 surround you've got two decent options.
One is to find a recone shop that has the flexible PVA. Electro-Voice uses two different formulations, one for cloth surrounds(semi-flexible), the other for foam surrounds(flexible)...these are known by the brand name "Airflex". This is the method I use to make simple surround patches when one doesn't want to pay for a recone and just needs a "fix" to get up and running.

The other option is to sparingly use black silicone weather strip sealer like that by GE found in hardware stores. Apply it sparingly to the folds in the surround and next to the cone and spread it evenly around the perimeter with your finger, then let it cure for 24 hours.

- I'm glad you articulated these two approaches to "temporary fixing" the old surround. In the distant past , I've successfully used the 2nd as a temporary bandaid on a couple of 2225s . ( Though I didn't want to bring it up without a leadin from someone with more seniority in this area. )

[edgewound]

Hi Ken,


- As a professional reconer , what leads you to make that statement ?

- Is it the cost of all the additional prep-time needed ( like neatly cutting out the old surround ) to get a nice-fitting, good-looking result ( ie; this approach being labor intensive & therefore reflected in the final price ) versus the known cost & time of a straight recone in a cleaned up basket ?

- I have a few surplus 2225s and am mulling over installing some of Rick Cobbs foamed surrounds to create a lowered Fs , short coil hybrid . Hence my interest in your answer .

Hi Earl...very perceptive of you . BTW, I have tremendous respect for your electronics calculations....your attention to detail is most impressive and I might say...rather intimidating .

The preferred method to replace a surround is to completely remove all traces of the old surround, and that's kind of a time consuming task to do it cleanly with the cone assembly still in the frame. The JBL cloth surround drivers are heat pressed on to the cone...some cross-linking can occur in the process and damage to the cone is not always easily avoided upon attempted removal of the original surround. The coating on the JBL surrounds is a never-completely-cured epoxy which is tough to tame.

Your idea of foam surrounds on 2225's should bear some caveats...you might want to electrically limit the excursion so you don't drive the coil out of the gap, or use a PR enclosure....but I'm sure you could make it work...would be very efficient.

[Earl K]

Ken, Thanks for your reply !

[imtkjlu]

Thanx all of you for all responses.
I don't now if my 2205 needs new cones or spiders ( I will take a photo of the spiders).
I think they sounds great!
They have never been abused and have been stored for last 15 years.

The pva just sounded ok to fix a nice black look...

But probably I will not do it because I may destroy them....

Cheers
///Kjelle

[Rudy Kleimann]

Do metal objects fly toward them???
I dont know how much charge they supposed to have.
But the only thing i would do to the actuall driver by the look of the photo is a recharge if a shifter wont stick to it

maybe ill get in all kind of shit for this!

Unlike Ceramic/Ferrite magnets, Alnico magnets have very little "stray" magnetism and do not hardly attract ferrous metal to them even when they are newly charged. So this would hardly indicate a weak magnet.

[boputnam]

...an alnico magnet can lose it's strength...

Don't forget to refer readers to the The Great Alnico / Ferrite Debate thread. It's all there.

[Rudy Kleimann]

Thanx all of you for all responses.
I don't now if my 2205 needs new cones or spiders ( I will take a photo of the spiders)...
///Kjelle

From what I CAN see, those drivers look pretty darn good. A picture of the cone/spider area will help. Those cones, and the yellow markings on the back look original to me. My 2130's are of the same vintage, and have the same yellow pencil markings.

If the spider is flat -not sagging (dished in or out) inward or outward- along the corrugated area from the outer perimeter to where it meets the cone, then they are probably fine. If the cones aren't showing any signs of "wrinkling" or tears (I didn't see any sign of this in the pictures), then the cones are fine.

If the surrounds aren't torn or cut along a great distance, then try the following:

Carefully push the cone into the magnet by applying even pressure all around the dust cap. Pay close attention to any sign of the coil rubbing or scratching inside the magnet. This is not easy to do, as the clearance between the coil and the magnetic gap it runs in is extremely tight. If you are good, you can do this by hand by using all your fingers and thumb evenly around the cap. Or, use a cardboard tube or piece of PVC pipe with a square-cut, smooth edge that contacts the cone right at or slightly larger than the dust cap diameter. Listen carefully, and observe any sensations felt by your fingertips for signs of coil/magnet contact. Another method is to apply a low frequency sine wave to the driver out of the cabinet. Get the cone moving visibly, and listen for any scratching sounds.

Check for short-circuits of the voice coil by connecting an ohmmeter to the speaker terminals and an unpainted portion of the speaker magnet or frame. Check the DCR of the coil to the range of DCR for the same driver in the JBL specs. Most driver DCR ranges are available elsewhere here or on the jblpro website. You'll have to do some digging.

If all this checks out, and you know a good speaker repairman, you could simply R&R the Dust Caps if needed and repair or replace the surrounds the way Edgewound and Earl K suggested and you should be good to G-O.

I've done quite a few recones, and a few "unusual" patch jobs, but I won't claim to be the ultimate authority. Any input or corrections from the Pros here?

[boputnam]

Carefully push the cone into the magnet by applying even pressure all around the dust cap. Pay close attention to any sign of the coil rubbing or scratching inside the magnet. This is not easy to do...

That is unreliable.

If you seriously want to do this, lay the frame on it's motor and slowly run a frequency sweep, using a 2 to 3 volt drive. Better yet, get the transducer to a pro you can trust.

[Rudy Kleimann]

That is unreliable.

If you seriously want to do this, lay the frame on it's motor and slowly run a frequency sweep, using a 2 to 3 volt drive. Better yet, get the transducer to a pro you can trust.

You got your eye on me, don't you, Bo?

I also suggested the test tone method in the next sentence. He may not have the means or ability to do this. Gotta play the cards you're dealt...

While the manual method may not be totally reliable, it's better than not not checking it at all. Wasted time, effort, and $$$ attempting a repair, only to find the coil fails from a rub that went undetected.

[moldyoldy]

Just a side note for any that try the "manual" method. The driver in question MUST be disconnected from amps, networks, etc., or you'll likely condemn a few good speakers this way. When the coil is moved manually, it acts like a microphone and produces a signal. If the coil "sees" any load connected, you'll feel/hear what you'll swear is a coil rub. The effect may not be noticeable on cheap, inefficient speakers, but it sure is on the close-tolerance, efficient drivers we mess with. Next time you've got a loose 15" on the bench, throw a jumper across the terminals and try it. I've even checked for open coils in the field when I was without a meter or battery this way.

Typical disclaimer, don't try this at home, etc., etc. It DOES require a practiced touch.

[boputnam]

You got your eye on me, don't you, Bo?

Not at all.

We just strive to encourage best practices here, rather than "quick and dirty"...

Manual movement of the cone yields non-reproducible and meaningless results. These could mislead that there is no problem, or that there is a problem. Better to not recommend something that doesn't work reliably.

As well, pushing on a cone only tests IN motion - I thought you were all about OUT cone movement...!!

.

[Rudy Kleimann]

Not at all.

We just strive to encourage best practices here, rather than "quick and dirty"...

Manual movement of the cone yields non-reproducible and meaningless results. These could mislead that there is no problem, or that there is a problem. Better to not recommend something that doesn't work reliably.

As well, pushing on a cone only tests IN motion - I thought you were all about OUT cone movement...!!

.

Good phase pun there!

[Rudy Kleimann]

If you ship a driver with a high-compliance suspension, it couldn't hurt to connect a shorting lead between the speaker terminals. Lord knows what those packages are subjected to bouncing down the road, going through conveyors and chutes in Dist. centers, etc.

We used to have sensitive analog instruments that required a shunt wire across the leads to damp the meter's needle movement during storage and transit. Makes a major difference in the effect of vibration on moving the needle; same goes for subwoofer cones.

Just a side note for any that try the "manual" method. The driver in question MUST be disconnected from amps, networks, etc., or you'll likely condemn a few good speakers this way. When the coil is moved manually, it acts like a microphone and produces a signal. If the coil "sees" any load connected, you'll feel/hear what you'll swear is a coil rub. The effect may not be noticeable on cheap, inefficient speakers, but it sure is on the close-tolerance, efficient drivers we mess with. Next time you've got a loose 15" on the bench, throw a jumper across the terminals and try it. I've even checked for open coils in the field when I was without a meter or battery this way.

Typical disclaimer, don't try this at home, etc., etc. It DOES require a practiced touch.

[loach71]

PVA is PolyVinyl Acetate. It comes in different formulations and differing flexibilties. The most common type of PVA would seem to be white glue such as Elmer's Glue.

Morbo's suggestion is simply to dilute the white glue till it's watery and paint it onto the cone to hopefully bolster a tired, fatigued cone. The added mass will be negligible. Fitting a new cloth m-roll surround is typically a losing proposition.

Look...were talking about a speaker that can still be used since the voice coil still works. Band-aid fixes are not illegall and we're usually talking about non-critical playback listening....to make the speaker at least function untill you can afford the right recone to renew the speaker.

If you've got cracks in the 2205 surround you've got two decent options.
One is to find a recone shop that has the flexible PVA. Electro-Voice uses two different formulations, one for cloth surrounds(semi-flexible), the other for foam surrounds(flexible)...these are known by the brand name "Airflex". This is the method I use to make simple surround patches when one doesn't want to pay for a recone and just needs a "fix" to get up and running.

The other option is to sparingly use black silicone weather strip sealer like that by GE found in hardware stores. Apply it sparingly to the folds in the surround and next to the cone and spread it evenly around the perimeter with your finger, then let it cure for 24 hours.

I'd rather do these fixes on an injured, working JBL cone assembly than waste my money on an aftermarket cone kit with the wrong electrical and dimensional properties...the voice coil is the heart and soul of JBL drivers, and wrong ones just sound wrong.

I hope these Band-aid solutions are helpful to you.

http://www.airproducts.com/Products/...rflex810-b.htm

Is this the AirFlex as per above?