2235 Break in Time

[Anton]

In my previous message I said the sound I get from
my system 2235,2123, 2420, sounds great .
For the heck of it I ran a audio generator test
and was a little dissapointed that the 2235 was
not responding in the lower 50 to 30 hz range
as I figured .
The 2235 had been refoamed by a reputable person
could it be it is too stiff and needs time to
break in . the 2123 were brand new units .do they
also need time for breaking in

Thankyou

[jblwolf]

I have refoamed many JBL speakers and yes there is a break in time,it also makes a differents what the surround is made of/condition of the spider,I have seen many different types of surrounds some very thin(looser),some much thicker,the thicker(stiffer)the surrond the longer the break in time,20-25 years ago it was tuff to find replacement surrounds so you had to use what you could find,now there all types of choices and at a cost of less than $5.00ea I can afford to buy different styles/thickness to see what fits/works best,I had a pair of LE15 that really started to sound good after about 100 hours of use,right after the refoam they had good bass,but now they really kick out the bass -Wolf

[Anton]

It seems that the surround and the spyder seem to be
kinda stiff and I had a hunch they might need some time to break in
Long ago I remember reading where someone was building a small sytem and he
sat the 6" speaker on a bench and ran 60 hrz thru it
for over night .
Thanks for the Info

[Rolf]

Hi.

I really dont't understand why you refoam. Why not re-cone? This is the only thing JBL recommend. You don't really know the condition deeper inside your speaker???

And yes...they need a 100-200 hours to play good.

Rolf

[jblwolf]

ROLF,to answer your question,1-is cost 2-keeping the original as original as can be kept original, 3-in my opinion the vintage parts are better than the replacement.that is if you can find the right replacement at all,I'm a big fan of the le15a and I have seen and heard what JBl and others calls their replacement kits for this model, (in my opinion) it does not meet the old standard,as for JBL recommends they love selling cone kits and no one can do it better than they can ,I have went as far as ordering new spiders,so I could use the original coil/cone-call me crazy or a original parts freak,but to me vintage is vintage and you cant replace that quality-I wonder how much it would cost to build a LE15 today at 1960/70's standards?or for that matter a Mcintosh or a Fairchild 100 watt tubeamp?I would even bet that alot of the home driver kits are no longer available,they may have what they call a equivalent(pro model kit)but is it the same as the original?-Wolf

[Earl K]

Hi Wolf

Originally posted by jblwolf
1-is cost 2-keeping the original as original as can be kept original, 3-in my opinion the vintage parts are better than the replacement.:-Wolf

I must follow your #1 guideline since parts cost in Canada track our exchange rate. That doesn't make for a pretty "cost of repair "picture. I also follow your points #2 & #3 to various degrees . I agree, that if a cone & coil are in decent shape, why trash it ? This old le stuff deserves better than that if it can be saved . I refurbish the old Lansoly surrounds on le10s & le14s but haven't yet gotten into having spiders changed. I'd like to pursue that at some time soon . I have a few questions about swapping out spiders .

I don't want to become a reconer, but I will dabble in "triage", getting the patient prepped for my local reconer to center-up & glue .


Is this spider changing something you've personally done , or was it done by someone else ?

How does one get an old spider off of the voice coil without leaving the old spiders' glue line ? ( this question also applies to dustcaps )

Are there specific solvents that will do this for the old & new style JBL glues .

Are these solvents harmful to other parts of the assembly ? ie papercone , coil former , surround , etc.

If you were planning for future - refits , is there an alternative type of glue to use that's easier to remove ?


Thanks for any answers to the above <> Earl K

[4313B]

Long ago I remember reading where someone was building a small sytem and he sat the 6" speaker on a bench and ran 60 hrz thru it for over night .

Never set a JBL transducer with a vented pole piece flat on a bench for break in.

I usually break in a transducer such as the 2235H for 4 hours at 20 Hz. This is sufficient to drop the Fs 6 to 12 Hz and all is well once that occurs.

[4313B]

For the heck of it I ran a audio generator test and was a little dissapointed that the 2235 was not responding in the lower 50 to 30 hz range as I figured .

Well, after breaking it in see how it sounds. It could be the compliance of the new surround doesn't meet spec and you are SOL. Fairly large shifts in compliance can be acceptable but too much can be quite undesireable.

[luxmanlover]

How much power do you apply to the transducers while they are in break in?
Kelly

[4313B]

10 volts at 20 Hz for the 2235H.

[jblwolf]

Earl,yes,I have did the spider replacement myself and many other repairs,I would recommend taking it in,my background goes back more than 25 yrs, when I had the opportunity to work at a local JBL dealer as a tech(he even paid to send all techs for training@JBL and tickets to the US fest too boot in the early 80's)and learn most of the repair techniques that a local dealer would be set up to do,I'm way passed that point now,I even ordered throats for 375 drivers,thinking I could repair them but enough is enough but I still may try it,the damaged 075's I rebuilt work just fine but it really should stop somewhere.but getting back to having the know how,parts will be hard to come across,years ago JBL would sell spiders to their dealers for that repair(JBL may say they dont but they did),but now?same goes with surrounds,I had to shop at least 4 different places to get the right size surround for the 136's and the le15's,and when it comes to the le14 thats another story.just as never cutting off the dust cap then you replace the surrounds-to this day I never needed to take the dust cap off for replacing just the surround.then there the glue,I only use 2 types- both came from JBl in tube/bottle form, I had a good suppy,Im down to my last 10 or so that I had for years,ones blk - the other brown,I use lacquer thinner-Qtips for all the clean up of old or new glue-learning on vintage equipment I feel should at some point be left to the pros ----Wolf

[4313B]

Hi guys,

MEK (Methyl Ethyl Ketone) is the "official" solvent used to remove the brown JBL glue (Bostic). You can pick it up at any good hardware store. Don't get it on the foam surrounds, they will expand and sometimes won't go back to normal after drying, especially if you touch them or fuss with them while wet.

http://www.nsc.org/library/chemical/Methyl_E.htm

[Rolf]

Hi. Cost I can to a certain point understand. Keeping it as original as possible? Well ok, guess it it like having a veteran car. BUT to say that the cone of a 2235H is not as good as the original 2231A cone, well, I not sure about this. Maybe Giskard knows.

Anyway, with repect, it seem to me that it is not the sound quality that matters, but to keep the speakers in the most original condition.

I use my 4333A's for music, and want them to sound best possible. That is why I change and modify them.

Rolf

[Earl K]

Hi All

Thanks for the answers guys.

Does MEK dissolve the "Black" JBL glue ?

regards <> Earl K

[4313B]

"BUT to say that the cone of a 2235H is not as good as the original 2231A cone, well, I not sure about this."

The 2235 cone is superior to the 2231 cone. It offers increased linearity and control. It's one of those evolutionary improvements in LF transducer technology John Eargle refers to.

Arguably the best cones were those made by Hawley before it's demise. Hawley has since resurfaced but I don't know if they have a relationship with JBL anymore.

If one prefers the sound of the original LE15 cone assembly to the current LE15 cone assembly who can argue?

"Does MEK dissolve the "Black" JBL glue ?"

Yes, I've been told the black glue is dyed Bostic. We carefully paint the brown Bostic black to match the dyed factory Bostic after finishing a recone. The recone kits only come with tubes of brown Bostic.

"as for JBL recommends they love selling cone kits and no one can do it better than they can"

I'm pretty sure JBL would just as soon ashcan all the old cone kits. They're a pain in the ass. To sell spiders and foam surrounds would further compound an already precarious issue. Frankly, I'm awaiting the day JBL simply marks all these kits NLA. This is just my perception and I could have it all wrong but more than a few have already been so marked. A full recone is expedient and cost effective from a labor standpoint. Plus it is an integrated fully functional unit. Few people can handle refoams let alone spider replacements. Look at all the crap on eBay with their amateur refoam jobs. I understand the premise and support it in theory but the current level of expertise generally isn't there and JBL doesn't appear to be all that fired up to rectify the situation. Basically, the deal is, if some fifteen year old kid wants to buy a refoam off ebay and "do" his "old" LE10's in his dad's hand-me-down L96's nothing is going to stop him. Unfortunately the rest of us have to suffer viewing the crap when it surfaces on ebay. Then a full recone is the only option because the refoam job was such a hack.