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View Full Version : Compliance adhesive - potential aftermarket option for DIY



DMMD
06-10-2005, 11:23 AM
Interesting conversation with an engineer working on Focal/JMlab. Talking about glues... and the use of 3M 1300L and 847L for foam-basket compliance. Although just 2 of the nearly 30 glues that JBL uses/has used....both seem to be in recone kits along with Moyen.

Anyway, he noted that 3M Weatherstripping Adhesive 8001 seems to be a close consumer eq of 1300L. He has used both, with the advantage being that 8001 is avail at several autoparts and marine parts chains.

Foam bonding family is the same, set time is same, base material is slightly diferent (but both rubbers), viscosity is thicker (but easy to smooth).

Anyone here used this as a substitute? Anyone think that it won't work? Just stick with waterbased white/clear goo and the weaker bond?

http://multimedia.mmm.com/mws/mediawebserver.dyn?LLLLLLuS1X&Leo4Lyo4LLLWspw2PB3rt-

GordonW
06-11-2005, 08:12 AM
I've never had a case where the bond from foam/paper with white glue, wasn't STRONGER than the materials themselves. And, if you leave a thin film of the original adhesive on the basket, the white glue will bond to that, stronger than the internal strength of the foam surround itself, too...

So, the weatherstrip adhesive may be stronger than that, but will it really matter? Only if you're going overboard, and cleaning baskets down to bare metal... that's the only case you would need to use something like this.

Regards,
Gordon.

edgewound
06-12-2005, 01:05 AM
"So, the weatherstrip adhesive may be stronger than that, but will it really matter? Only if you're going overboard, and cleaning baskets down to bare metal... that's the only case you would need to use something like this



Dear GordonW....Did I hear(read)you correctly? Cleaning the frame down to bare metal is going overboard?

With all due respect, Sir, I believe the terminology is doing it right. If you leave any old surround or glue material on the frame, you're doing an incomplete job and not doing the professional job your customers deserve. Any excess old gunk left on the frame will certainly alter the resting position of the cone/voice coil and therefore adversley affect the performance of the repaired woofer. I'm sorry....but it's exactly the same as rebuilding the heads on an engine without degreasing the block first and scraping off ALL of the old gasket material. If your going to get paid to do it....do it right....thoroughly.

Thanks for listening...and it's not my purpose here to offend anyone.

Edgewound

4313B
06-12-2005, 06:37 AM
You always clean the frames to bare metal. That's a given.


it's not my purpose here to offend anyone.Understood. That's my job.

Guido
06-12-2005, 08:24 AM
Hope nobody mind me jumping in here.

The JBL-Pro Importer for Germany can't sell me the bostic glue any longer! He told me it was to dangerous to work with and JBL stopped it. Moyen should work as a substitude.
I already had 2 cone kits that came with moyen only but prefered to use my spare bostic glue first.

What do you guys think?

4313B
06-12-2005, 09:22 AM
I like the Moyen better myself. Didn't at first (a change), do now. You should be able to buy the Moyen as a misc part. I think it's something like $7 a tube.

Guido
06-12-2005, 09:38 AM
I like the Moyen better myself. Didn't at first (a change), do now. You should be able to buy the Moyen as a misc part. I think it's something like $7 a tube.

Good to see ya back ;)

4313B
06-12-2005, 09:47 AM
Good to see ya back ;)I'm only here to answer specific questions. I'll endeavor to stay out of the continual stream of inane threads about such things as L100's and their impact on human society, various opinions and all that kind of crap.

norealtalent
06-12-2005, 10:19 AM
I'm only here to answer specific questions. I'll endeavor to stay out of the continual stream of inane threads about such things as L100's and their impact on human society, various opinions and all that kind of crap.

This is what makes the Forums so interesting,we can and do challenge each others opinions but at the end of the day its all just for grins.

Ian[/QUOTE]

http://audioheritage.org/vbulletin/images/smilies/biggrin.gif http://audioheritage.org/vbulletin/images/smilies/biggrin.gif http://audioheritage.org/vbulletin/images/smilies/biggrin.gif http://audioheritage.org/vbulletin/images/smilies/biggrin.gif http://audioheritage.org/vbulletin/images/smilies/biggrin.gif

Speaker disease, we just can't beat it. I was trying to stay out of it before I realized I had it.

4313B
06-12-2005, 10:51 AM
This is what makes the Forums so interesting,we can and do challenge each others opinions but at the end of the day its all just for grins.

IanThat would be an opinion I no longer share. My point is that I am no longer interested in getting sucked in to speculation, conjecture, personal opinions, etc. on the subject of loudspeakers. That should be fine with everyone. Most people can't seem to handle my kind of discourse. If I can answer a specific question then great.

Here the topic is compliance adhesive -


353353-001 ADH,MOYEN,(QT),PACKED IN 41.50 $ USD EA

353196-001 ADHESIVE TUBE, MOYEN 308 7.00 $ USD EA

Ian Mackenzie
06-12-2005, 02:54 PM
My quote above was taken completely out of context. I really hate that.

I used the phase in another thread to dowse inflated opinions that were in my view unsupported by any fact....I hate that...that sort of thing belongs in the general forums. We do have a problem with mis information around here particularly when people start poking around with original designs.

When however technical issues like reconing are a topic of discussion....there usually is only a right and wrong way.

Ian

GordonW
06-12-2005, 08:36 PM
Almost all JBL baskets are painted, or coated with something under the glue. Are you all seriously advocating, taking off the factory PAINT? Because "taking it down to bare metal" would be making the recone MORE UNLIKE the original status, than leaving that paint (and the tiny film of Moyen glue that has penetrated said paint) would be.

And seriously, if anyone thinks that the thickness of a film of glue (after wiping it down with solvent, to rid any of the "chunks" of anything that might remain from an old surround) is going to change the resting position of a surround enough to make even a remotely measuable (much less listenable) difference, I recommend they lock themselves in a room with a Dumax analyzer, an FFT and/or a LEAP/LMS system and test for themselves. I defy anyone to show differences, that even come CLOSE to the magnitude normal driver-to-driver and kit-to-kit manufacturing differences. Just the difference between the molding/stamping of TWO PAPER CONES compared to each other, will make a bigger sonic difference.

It's really a matter of understanding what makes a difference, and what doesn't mean diddly $#!^... to put it bluntly.

And it's funny, that this would even be an issue, when there's actual honest-to-god JBL current EMPLOYEES, that say PUTTING THE SURROUND ON THE FRONT of a 128H cone DOESN'T make a difference in the sound, as evidenced by threads here previously. Why not call out the people that are really burying their heads in the sand, maybe?

Regards,
Gordon.

edgewound
06-13-2005, 12:32 AM
Well that's right, Gordon...and one of my points exactly. The micron, or so, powdercoating is an original application at the factory, and not until the 1980's. Early Jim Lansing, JBL/ Altec were bare metal the the surround landing...I've seen it...be cause I am factory trained and certified to RESTORE JBL products to FACTORY current specs. Let's not forget that this forum is call "Lansing Heritage"...not "Aftermarket...let's try to get close...to Jim Lansing products". I agree with Robh3606 on what the factory does and doesn't sanction as far as repairs to JBL products is concerned. And a foam surround replacement is one of them. Let's face it...it's not cheap to recone these various works of art and science with a Genuine JBL recone/diaphragm kit. But on the other hand...if you are going to do a foam surround replacement...you damn well better do the art work to look as factory original as possible...it's your responsibility as a preserver of this art form. If you dare put a foam surround on the front of a 128H, 128H-1, 122A, 126A, 129H, 125A, 127A, LE111A, LE10A, 2231A, 2235H, 136A, LE15A, 2215A...believe me there's more , 'cause I've done 'em all...cone...you've just RAPED the greatest legacy of American audio innovation...and screwed your customer in the process....Yeah, I know...a number of LE14A's with Lansalloy surrounds was installed on the front of the cone. People that bought JBL Vintage products are not stupid. But alot of aftermarket reconer's think they are....very often, the customer will opt to recone the speaker with a factory kit than do a surround replacement....unless you've done the factory recone before and have the reputation among the community to replace a rotten foam surround cleanly and original looking....it's an economic choice that becomes a win-win for customer and servicer. There are PLENTY of JBL's on eBay that are being passed off as ORIGINAL JBL parts, when they are in fact aftemarket wanna-be's...and good people are being ripped off. Talk about the proverbial Caveat Emptor. If you think for a minute that how you actually restore this stuff doesn't matter....you shouldn't be putting in your two cents here....because it's worth less than that. I found this forum by Google search and was blown away by the passion of the creators of this site, for the preservation and sharing of the historical meaning and significance that James Bullough (Martini) Lansing and his associates contributed to the landscape of American industry, and the scientific artform that set the standard for audio products around the globe. Am I passionate about this? You bet I am. Being JBL Authorized isn't to be taken for granted. I had prove to JBL Professional that I was qualified to represent these great legacy products...I was interviewed by the National Sales Manager at JBL Professional, as to why I thought I was qualified to be in business, and then I was trained and evaluated by the late Terry Duran who was in charge of training recone technician candidates at the factory in Northridge, CA. And believe me...not all candidates were certified. Some were rejected....didn't have the talent or patience to do it right. I'm proud to be a representative of JBL in the field, and I'll call out anyone who diminishes it....our heads are not in the sand! My kudos go out to the likes of Don McRitchie, Mr. Widget, Giskard, BoPutnam, Robh3606, Ian....I'm sure there are more....you guys really "get it"....I'm honored to have found this place.


I will now step down from my soapbox.

Respectfully,

Edgewound

Ian Mackenzie
06-13-2005, 02:21 AM
I know I said Welcome Edgewound but Jesus.....:rotfl:

No need to step up to the Plate!

And I think Giskard can take his boots off.

Oh Well at least someone was paying attention to the last sentence in post 11.

I have to go to work tomorrow...Edgewound..please carry on.

Muhhahahaahahah.

Ian

Guido
06-13-2005, 03:47 AM
........... Let's face it...it's not cheap to recone these various works of art and science with a Genuine JBL recone/diaphragm kit. But on the other hand...if you are going to do a foam surround replacement...you damn well better do the art work to look as factory original as possible...it's your responsibility as a preserver of this art form. .............
Edgewound

YEP!

But I would like to mention the 5% genuine kits that come with slightly sloping voice coil which makes centering an real art and the cones with spoiled glue on it that work well but look :barf:

Technically ok says the pro-importeur and does not exchange them.

;) OK the other 95% are dead fits!

Alex Lancaster
06-13-2005, 07:47 AM
:) The factory paint is much thicker than a micron, which is a millionth of a meter, (.00003937"), the coating is more like .001"; I took the course at Northridge; when speakers arrived to be serviced, a grunt would clean them with a knife and MEK, pass them to the reconers, where We would clean them more, airblast and clean the gaps, check for shift and magnetism; anyway they were never cleaned to bare metal, there was always a coloring of glue left, maybe .001" thick?; If anybody wants to take the trouble, put one on a lathe and You will see how inexact they are, after all, they are die castings.

So, I think Gordon is right.

DMMD
06-13-2005, 08:17 AM
The MEK removes all the glue. Anyway, this is yet another pointless argument. Do whatever you want. As for reconers, they all think they're good, some of them do great work and others are delusional. What's good enough for some doesn't pass the bar for others.

:applaud: Well put... and I'm glad my original point became a little soapbox. It's good to see NEW people who are passionate about preservation and true craftmanship and are willing to put their foot down. I'm tired of also-rans who masquerade as "professionals" in ANY industry. If you chose to do it that way yourself, for whatever reason, then fine... to each his own. BUT, the equation chages when you are hired as a "professional." Just because there is an easy fix that saves YOU time and money while unlikely to rock the boat of your ignorant (or shy) customers doesn't give you the license to embellish reality.

Yes, I've been dissed by shameful reconers... and chastised here for not calling a spade a spade. It happened once, I learned my lesson. Now I am not lazy about it anymore.

Now.... to qualify the original point of this thread: My search for a suitable OTC adhesive was just that... to find a product that behaved like and had the composition of the gasket/rubber adhesives that have to be special ordered.... whether from JBL directly (or a 3M...or a Moyen dealer). I provided a link to one option that is a useful substitute.

Sure, there are a lot of glues that will "work"... but that's not the POINT! Professional is spelled with a capital 'P' in my book. That goes for DIY too.

So, when your glue supply dries out and doesn't re-activate here's an option worth looking toward.... simple as that.

DMMD
06-13-2005, 08:21 AM
Part I: If your going to get paid to do it....do it right....thoroughly.

Part II:

...I guess I feel that sometimes we just have to stand up for principal when we think...or know... that the pursuit of excellence in ANY field is being pushed aside. Don't get me wrong...I do not know everything, nor do I profess to. But when I'm right...I'll fight

Edgewound

Can I print this out and mail it to the local JBL "reconer?" :applaud:

Sorry doobie... Award-winning "Glue Art" doesn't count when it's on transducer cones.:blink:

I think Sir Edgewound may have earned some new business here in SoCal.

edgewound
06-13-2005, 10:31 AM
Yes you may, DMMD. You're support is appreciated:) .

Have a great day,
Edgewound

edgewound
06-13-2005, 10:45 AM
I know I said Welcome Edgewound but Jesus.....:rotfl:

No need to step up to the Plate!

And I think Giskard can take his boots off.

Oh Well at least someone was paying attention to the last sentence in post 11.

I have to go to work tomorrow...Edgewound..please carry on.

Muhhahahaahahah.

Ian

Thanks for the love Ian...I guess I feel that sometimes we just have to stand up for principal when we think...or know... that the pursuit of excellence in ANY field is being pushed aside. Don't get me wrong...I do not know everything, nor do I profess to. But when I'm right...I'll fight (wow...poetry):biting: . Something has happened along the way the past couple of decades. Finding a quality service tech in ANY industry seems to be a job in and of itself anymore. Had your oil changed at a Jiffy Lube lately? How hard can it be to screw that up? But somehow they manage to....and I change the oil myself now....Geez...I could go on and on....but I won't....you already know this.

G'day mate,

Edgewound

Oldmics
06-13-2005, 11:59 AM
Originally posted by Edgewound


" and then I was trained and evaluated by the late Terry Duran who was in charge of training recone technician candidates at the factory in Northridge, CA."

Now there was a great lady!!!!!

I do miss her.She had all of the answers.

When I took the course, I specifically asked Terry about the adhesive (bostic at the time) and its ability to bond to not perfectly cleaned frames.

Her reply was that the bostic was formulated to overcome any SMALL amounts of debris that were on the frame to be reconed.

Oldmics

GordonW
06-14-2005, 08:55 AM
I'm sorry... don't even get me started with so-called "JBL Authorized" service centers. After having to pick up the pieces of what the local "JBL Authorized" service center sends out (otherwise known as surrounds glued on the wrong sides, kits that were never shimmed/centered properly, sending out the WRONG kit on a recone, to name just a few), I really don't care to hear anyone preach to me about "correct work". I've brought back MORE speakers that were said to be UN-REPAIRABLE, to a condition where they LOOKED, and more importantly, MEASURED like the originals. JBL, Goodmans, Gauss, EV, you name it... my work looks and sounds more like factory parts, than many of the people "authorized" by the factory to do so. I defy ANYONE to find ONE piece I've done, that wasn't the BEST it could have been...

So, pardon me, after dealing with BS from these guys for the last 10 years, if I don't really take "JBL Authorized" as any sort of ringing endorsement. Maybe it was different when Terry Moran was in charge, but it's certainly a "brave new world" out there now, from what I've seen from the CURRENT crop of "JBL Authorized" repair centers...

Regards,
Gordon.

DMMD
06-14-2005, 09:01 AM
So, pardon me, after dealing with BS from these guys for the last 10 years, if I don't really take "JBL Authorized" as any sort of ringing endorsement...

Regards,
Gordon.


JBL should....if they still care. "Authorized" still means something and in most cases it yields accurate results. It's simply unfair to bash them in general.

I still have faith...

Quality of craftmanship and pride are the exact reasons why you can still call JBL and find a part for a 50 year old product. That's the point of their whole MO. It is also a testament to a company that can still get parts to those who can effectively represent their products via an experienced network with a very rich history.

Unfortunately, I don't think this strategy fairly reflects the reality of the black and grey areas in an internet powered, greed-driven marketplace. Likewise, JBL's legacy is tarnished in a marketplace where small business is driven to value speed and cost over quality workmanship and.

It's time for JBL to again find creative solutions that empower/reward those who can do a proper job and disuade those from making a quick buck from JBL's good name.

GordonW
06-14-2005, 10:22 AM
:) The factory paint is much thicker than a micron, which is a millionth of a meter, (.00003937"), the coating is more like .001"; I took the course at Northridge; when speakers arrived to be serviced, a grunt would clean them with a knife and MEK, pass them to the reconers, where We would clean them more, airblast and clean the gaps, check for shift and magnetism; anyway they were never cleaned to bare metal, there was always a coloring of glue left, maybe .001" thick?; If anybody wants to take the trouble, put one on a lathe and You will see how inexact they are, after all, they are die castings.



This is absolutely the case. I've seen speakers, that had been sent to JBL themselves for reconing (due to shifted magnets, weak alnico, etc), and it was obvious that they had not gone down to "bare metal". themselves. It'd be counterproductive to do so...

Also, about the inexactitude- there is no better example of this, than the way JBL lost their contract with NASA, in the 1970s, to Emilar. As it was explained to me by a former Emilar project engineer of the time, to quote him: "JBL couldn't hold a 1/1000"-magnitude-range tolerance, consistantly. At this time Emilar could easily hold 1/10000 tolerance in machining".

So, if this type of precision really did matter to JBL, then they really should have been doing it THEMSELVES...

Regards,
Gordon.

edgewound
06-14-2005, 12:40 PM
This has started to become a waste of my time....and good information.


Debating with unreasonableness...is unreasonable.

BTW....Emilar is no longer in business...must've run out of NASA contracts.

Have a grand day.

Oldmics
06-14-2005, 01:37 PM
Originally posted by Edgewound

"BTW....Emilar is no longer in business...must've run out of NASA contracts."

Emilar"s principals (2 outta 3 I believe) opened Radian

Oldmics

Lancer
06-14-2005, 01:54 PM
http://recone.com/jbl798b.htm

edgewound
06-14-2005, 02:10 PM
Lancer...

That's a great tribute to Terry...thanks for your post. She trained me in 1988.

Now that's Lansing Heritage.

Thanks again,

Edgewound

Ian Mackenzie
06-14-2005, 03:42 PM
Gee I never would have thought I'd see the day on the Lansing Forums where a member regardless of their status would use the Forums to publicly rubbish JBL authorized Service Centre(s).

Consider this thread closed...The Moderators may edit this thread at some point.

Ian

Mr. Widget
06-14-2005, 04:03 PM
I was asked to clean up this thread as a couple of members started taking pot shots at each other which is not tolerated.

I am not endorsing the posts that I left or disagreeing with the entire content of those I took down, but felt compelled to delete those posts that had content that included what seemed to me to be personal attacks.

It is fine to disagree, but let's keep it to the topic and not the individual.

Widget

John
06-14-2005, 05:11 PM
Well for what its worth I trained myself:p in refoaming JBL,s and I always take it down to the bare metal before the refoam begins. :bouncy: But I am freaky like that.

GordonW
06-15-2005, 10:53 PM
After giving it a lot of thought, I would like to issue a general apology to the "listening audience"... I did indeed allow myself to get overly overheated about percieved slights. And about something, that given EITHER approach to it, would result in VIRTUALLY NO difference in the end, anyhow.

There appear to have been several people involved with this thread that have become disproportionately "polarized" as a result of this discussion. All I ask, is that this behaviour STOP. It's too small a matter for such encampments to take place... there is no need to permanent enmity to come about because of anything of this sort.

But, in any case, I hereby step off my soapbox in this discussion, permanently. I just ask that others do the same...

Regards,
Gordon.

Mr. Widget
06-15-2005, 11:11 PM
Hey Gordon,

I allow myself to get overly heated about this stuff all the time... unfortunately since we communicate with each other through this medium, it is difficult to register the responses to our posts... we don't get the visual cues as we do in person to person conversation or even the audible intonations as we do on the phone... at the risk on continuing off topic I too would like to apologize to all those I may have offended in my thousands of posts... sometimes I am trying to be humorous... sometimes I am just being opinionated, but I never intend to anger anyone.

Widget

BTW: I think we should all go out and rip on Bose for a minute... oops, did I do it again?

edgewound
06-15-2005, 11:28 PM
Well...I guess that qualifies as an apology? So be it....if that's as close as it gets.

As long as this forum is named "Lansing Heritage"....and it is...I won't step down from my soapbox to preserve and/or restore the the very details of the Lansing Heritage. As I interpret it...when it comes to restoration, preservation or improvement as laid out by the factory's supported product...the devil is in the details...like it or not. If it's your purpose to rewrite, revise, or re-engineer history...and defame it...be prepared to accept Newton's Third Law.

In respect of Lansing Heritage,
I remain,

Edgewound;)

Mr. Widget
06-16-2005, 12:11 AM
Nothing like drawing an imaginary line in the sand to make friends... :(

Widget

Ian Mackenzie
06-16-2005, 12:50 AM
Yes,

But everthing here is more often than not war of words than anything else.

If you feel strongly about a post and wish to elaborate is a manner not befitting the public forums try sending a pm, state your case or arguement but be polite and respectful. Life's too short for sour grapes over a forum post and complaining about your sin to a moderator will not win any brownie points.

Remember you have probably never met the member your responding to or any inckling of his personaility but as they say preception is reality so choose your words carefully.

In fact I called The Widget myself this morning and it was joy to chat for a few minutes. I have also met a number of members both in the USA and locally and therefore have a good understanding of them.

Perhaps some of our member who are located in regional centres could get together occassionally.

Ian:)

Mr. Widget
06-16-2005, 12:56 AM
Remember you have probably never met the member your responding to ....

Good thing to, because I can get really rude to those I know.:p

Time for Widget to sleep... Zilch is going to start hammering on me for his plots.:duck::offtopic:

Widget

Ian Mackenzie
06-16-2005, 04:49 AM
And there are some who you'd rather only meet in your worst nightmare!:eek: :rotfl:


My story......Muhahhah

Now speaking of glues and bare metals I recall if you will forgive me getting hold of a 2245 refoam kit ages ago only because I already spotted a 2121 refoam kit for my brother when 2121's recones were out of stock perm. It was from Orange County CA and I figured for the cost the air freight why not. They sat idle for 12 months and then it happened one of my 2245 surrounds started to fall apart.

So eventually I attempted the refoam and followed Bo's nice instructions....the kit actually had very good instructions and it was clear from them that the gasket and all remaining glue be completely removed.

I admit it was a real effort and I used a solvent to completely remove the residual glue down to the metal. Otherwise the remaining glue would have caused an uneven surface for the new suround. I was glad I did it and recall telling Bo about how it went..not bad for a 1st timer.

It all went well enough but I only treated the refaom as a stop gap until I was ready to refoam both drivers together so I could be sure their performance and life span would be near identical.

My view from my experience is as woofer drivers age the spider and other apsects of the cone also age and fatigue particularly with high power usage so a true recone is very worthwhile.....a refoam is only after the job perhaps...I am no expert but I have owned a number of 2235H's and the recones always seemed to perform better after a driver was blown out by a 700B after a party and a misshap.

Perhaps Edgewound can advise us on wear and tear..excuse the pun?

Alas I never got arround to the reconing and bought a nos 2245 mint for the cost of a recone recently..so will have a backup if the unthinkable happens again (yes I intend to still get both other 2245s reconed by an auth service centre..probably Jands in Sydney..they are the Aust agents)

No doubt others have similar stories.

Aside from the new soa JBL 1500 FE/AL I consider the 2245H the grand daddy of all woofers in imho. They have excellent linearity and produce subjectively effortless bass with superb musicality.....why would you ever consider anything other than a genuine JBL recone.

Ian

Ps Does anyone recognise what the formulae is in my signature. The first correct winner gets and autographed picture from Otis!

boputnam
06-16-2005, 08:37 AM
As long as this forum is named "Lansing Heritage"....and it is...I won't step down from my soapbox to preserve and/or restore the the very details of the Lansing Heritage. As I interpret it...when it comes to restoration, preservation or improvement as laid out by the factory's supported product... Bingo. This tags a very important aspect we try and put proper attention to here - identifying and highlighting that specified by JBL factory spec and procedure, and that of personal experience / practice. It is crucial that JBL factory procedures be known by all us. If someone is advocating their personal practice or interpretation of JBL factory procedure, it should be so attributed. We need to sustain the original engineering and not relegate ourselves to a DIY forum.


If it's your purpose to rewrite, revise, or re-engineer history...and defame it...be prepared to accept Newton's Third Law. Bingo II. That is what we are trying to prevent, and to upgrade the quality of all our work as DIY'ers.

boputnam
06-16-2005, 08:47 AM
I did indeed allow myself to get overly overheated about percieved slights. You're not alone in that, Gordon.

Syntax and intended meaning are too often vague and left to the reader. Remember the old adage of "write the letter and leave it overnight before sending it"...? Well, that was very useful because very often we will not (and cannot) interpret our writing the way a reader might - and at heated times, the probability we will is much lower.

When posting, everyone needs to take a minute and consider their syntax and context, and at the end realize that their ego and reputation does not ride on being right / correct - it resides in maintaining a quality exchange of best-practices in a genteel manner. By that we will grow not just in numbers.

Oldmics
06-16-2005, 09:42 AM
"Ps Does anyone recognise what the formulae is in my signature. The first correct winner gets and autographed picture from Otis!"


Ian

Come on now,give us some clues.

As I see it you need to have the power functions defined. 10^-12
is 10 raised to the negetive power etc?I assume f3 is a function,but of what?

Oldmics

boputnam
06-16-2005, 09:46 AM
As I see it you need to have the power functions defined. 10^-12 is 10 raised to the negetive power etc? Yup, that was my read, too. And, f3^3...? Stopped me dead... :baby:

Earl K
06-16-2005, 10:08 AM
Hmmmm,

- Energy, along with extremely low numbers ( or losses ) , F3 is cubed, ????

- How about resistive energy losses from ports ? :blink: or a port velocity measurement ? ( that's the best I can conjure up right now )

- Okay, I'm clueless.... When do we find out ?

edgewound
06-16-2005, 10:12 AM
Nice insight bo...well spoken...er....written:applaud: .


Ian...thanks for your confidence in me:)



My view from my experience is as woofer drivers age the spider and other apsects of the cone also age and fatigue particularly with high power usage so a true recone is very worthwhile.....a refoam is only after the job perhaps...I am no expert but I have owned a number of 2235H's and the recones always seemed to perform better after a driver was blown out by a 700B after a party and a misshap.

Perhaps Edgewound can advise us on wear and tear..excuse the pun?




You party animal...

Well, your right in that you can't beat a recone with factory parts. Why? Because the factory recone kit is pre-assembled at the factory to OEM tolerances. When the recone is done right and with care...voila..you have an equivalent to a brand new speaker at less than half the cost...and as is the case with a number of JBL drivers, you might get the benefit of updated, improved specs....ok, then...

Wear...Yep...they wear out over time, especially with hard use. The mechanical parameters of a dynamic moving coil loudspeaker are always changing. That's why Pro Sound touring companies are constantly reconing the drivers before they blow...it's like a racing team rebuilding the engine between races. The suspensions fatigue...stretch out of shape. The spider will no longer hold the voice coil in its intended resting position and go non-linear, or worse yet allow the voice coil to slam against the back plate, or be driven completely out of the gap, causing sudden death....bummer, dude. And then the Compliance(surround, annulus) also fatigues,and in the case of foam...well, you know...it rots. BTW, so does Butyl...it just cracks. Nothing lasts forever without maintenance,especially with continual use.

Re-suspend....Yes it's possible to repair the speaker with a new surround and spider, as long as the voice coil and cone are still in good shape. It'll probably cost about half of what a good OEM recone will cost if you pay a good tech to do it right....and it should look and sound close to new. If you're the adventurous type and want to attempt the repair on a 2245 it'll probably cost $20-$30 bucks for parts and incidentals...but if you screw it up...might as well have it reconed.

I hope that's what your looking for, Ian. I love this stuff, but,Carpel Tunnel is setting in.

Till we meet again,

Edgewound

Ian Mackenzie
06-16-2005, 11:29 AM
[QUOTE=edgewound]
Wear...Yep...they wear out over time, especially with hard use. The mechanical parameters of a dynamic moving coil loudspeaker are always changing.That's why Pro Sound touring companies are constantly reconing the drivers before they blow...it's The suspensions fatigue...stretch out of shape. The spider will no longer hold the voice coil in its intended resting position and go non-linear, or worse yet allow the voice coil to slam against the back plate, or be driven completely out of the gap, causing sudden death....bummer, dude. And then the Compliance(surround, annulus) also fatigues,and in the case of foam...well, you know...it rots. BTW, so does Butyl...it just cracks. Nothing lasts forever without maintenance,especially with continual use.
/QUOTE]

Hmm, I think my backside needs a recone..any takers...:rotfl: :rotfl: :rotfl:

Ian

JuniorJBL
06-16-2005, 11:41 AM
Hmm, I think my backside needs a recone..any takers...:rotfl: :rotfl: :rotfl:

Ian


Um...... er.....:blink:

Ian Mackenzie
06-16-2005, 11:43 AM
E = 16 x 10(-12) f3(3) Vb k

What its saying E = conversion effciency = 16 times 10 to the power of minus 12 times F3 (-3 db point) cubed times Vb (box volume) times K is a system dependant factor usually 1-2 for sealed systems and usually 3-4 for vented systems.

But the question is what is this a mathematical expression of and what is it telling us?

A clue is what happens when we compare small versus bigger systems at low frequencies? Think of a practical example, a LE8T versus an LE15A, plug in the numbers and......what do you see?


I going back under the doona...:snore:

Ian

Zilch
06-16-2005, 01:58 PM
16 X 10^-12 merely moves the decimal 12 places thataway ----->

i.e., .016 nano-widgets, 16 pico-widgets times.

[Be not intimidated. They are vewy, vewy small....] :p

Mr. Widget
06-16-2005, 02:00 PM
Who's talking about small widgets? :applaud:

Widget

DavidF
06-16-2005, 02:30 PM
Yes,

...I have also met a number of members both in the USA and locally and therefore have a good understanding of them...

Ian:)

Uh oh. Does that mean you are not coming back?

DavidF

Zilch
06-16-2005, 03:20 PM
I have also met a number of members both in the USA and locally and therefore have a good understanding of them.

Ian:) As a student of this phenomenon, perhaps YOU can tell us what it's all about, then?

Ian Mackenzie
06-16-2005, 03:24 PM
David,

This threads only for members who've got a brain.

Otis just gave you the thumbs down so piss off and on't come back.

Ian

edgewound
06-16-2005, 03:52 PM
E = 16 x 10(-12) f3(3) Vb k

What its saying E = conversion effciency = 16 times 10 to the power of minus 12 times F3 (-3 db point) cubed times Vb (box volume) times K is a system dependant factor usually 1-2 for sealed systems and usually 3-4 for vented systems.

But the question is what is this a mathematical expression of and what is it telling us?

A clue is what happens when we compare small versus bigger systems at low frequencies? Think of a practical example, a LE8T versus an LE15A, plug in the numbers and......what do you see?


I going back under the doona...:snore:

Ian

I'll take a stab at it....

Would it be a ratio...of the differences associated with the bass response efficiencies of a sealed vs. vented enclosure at the -3 dB downpoint of the systems tuning frequency?...and the associated rolloff of the bass frequencies below the Hemholtz frequency of the tuned port due to phase cancellation? Maybe your countrymen Thiele and Small had something to do with this?

Fingers are crossed:blink:

Edgewound

DavidF
06-16-2005, 04:31 PM
David,

This threads only for members who've got a brain.

Otis just gave you the thumbs down so piss off and on't come back.

Ian

Is this a derivation of Hoffman's Iron Law and the inter-relationship among box volume, cutoff frequency, and efficiency?

Can I come back now, even if I am a little correct?

Ian Mackenzie
06-16-2005, 05:35 PM
Your warm, Otis is purring loudly.


Who wrote the formulae....R.......................Sm..........

Ian

Robh3606
06-16-2005, 06:15 PM
Richard Small??

Rob:)

Ian Mackenzie
06-16-2005, 07:00 PM
Correct,

So we have a tie , Both Robert and David are the winners.

Please pm me your details and I will organise your Otis photo autograph!

The actually forumulae was used in an article "The Sage of Bass" or something like that in Audio Magazine years ago.

regards

Ian

Ian Mackenzie
06-17-2005, 03:29 AM
Thankyou everyone who was involved.:)

I will post snippet of the article for your appreciation in the morning.

If you would like a copy of the article I am happy to email..send me a pm.

Ian