woofer problem

[sba]

Hello,

This is my first post, and I'd like to ask about a woofer problem.

I just picked up a pair of Celestion Ditton 66's (12" 3-way) and, after plugging them in, noticed that the sound from the woofers is totally distorted. The cones and surrounds appear okay though.

Upon lightly touching and moving the cones, I noticed that the movement is very stiff (almost seized), and that the movement generates noise and friction towards the back of the woofer.

Any idea on what's wrong, and, if so, is this repairable?

Many thanks,
Scott

[Cal Weldon]

Scott,

If there is noise (scratching, rubbing) when you push on the dustcap, you likely have a problem with the voice coil of the woofer. The usual way to deal with this is a recone. This gives you a new voice coil attached to the cone. If you have not done this, then it's best left to an expert. They will also be able to tell you if the motor structure is in good enough condition to do this.

Or maybe you can find some used replacement woofers.

[sba]

Thanks for your reply Cal.

I just found a replacement woofer on ebay (and picked it up locally). Wow, do these Celestions sound nice! Now I need to find one more replacement woofer.......I just don't have the expertise to recone a speaker.

Thanks again

[alan-1-b]

Email to Celestion and ask for their opinion on what is the most suitable alternate woofer made by who-ever today . Celestion will have had many queries about such , as the Ditton 66 was a popular speaker and many were sold , thus more than a few will have been overdriven and had woofer voicecoils failing !
Celestion's email address will be somewhere on their web-site , which I have forgotten the address for , so I'm sorry , but you will have to Search to find that - and which is how I originally did .
A 12" SEAS paper cone driver will probably work OK , and more-so if you chance upon one which has specs close to those of the Celestion original .

[sba]

Thanks Alan,

I sent an email to Celestion more than a week ago, and have not heard back from them (info@celestion.com).

I just found the second needed woofer on ebay. Actually, I had to purchase a pair of woofers.........from a guy who has very, very bad feedback on ebay......some of the bad feedback was about his describing things as being in almost mint condition, and when the buyers opened their packages, the items would be falling apart in their hands. There was so much bad feedback that it was almost comical......

Mine were described as being in perfect working order.......when they arrive, I hope at least one of them works well..... Wish me luck !

[alan-1-b]

I wish you luck ! - the chances that one has to take to get old parts !!
I have forgotten what those Celestion cones , and more relevantly the surrounds were made of - whether they decay with age and exposure to direct sunlight , as some types do , but as you have samples , I have no doubt you will have assessed such .
Before you install them , try very gently with your fingers spread wide , pressing down on the cone in the direction it is intended to move in , and listen carefully to hear if any even faint sound of something rubbing or scraping . Such could be an expanded voice coil from heat having distorted the former it is wound on , or part coagulating the insulation , or , if may simply be dust has got in . If soft dust , no harm , but rough grit in there will scrape insulation off the voice-coil wires . No , I don't know how to clean such out , but as you are in the USA , there may be a specialist who can - I'll try to find a web-site address I have forgotten , where you can enquire and I'll post it in this thread in a couple of days time I hope .
Test not only for electrical continuity , but also for possible short-circuit before you connect to your amp. Likely you already know this , but I always warn buyers of old speakers .
If both work , bit one is significantly quieter than the other , then the quietest of the 3 then you will have , may have a "dropped voice-coil" - basically a voice-coil can sag on its suspension and be partially outside the efficient area of the magnet's field . I have only owned one such , but after using it awhile , it developed a partial short , went lowish impedance and caused burn-out of the transformer in my tube amp , thus why I warn you about such , but if you do get one such , I advise you to research the subject , as it may still be useable .

[alan-1-b]

sba , try The Classic Speaker Pages at :- www.classicspeakerpages.net .

Some computers seem not set up to access this site , but I have accessed it via other computers with no trouble .

Basically , it is an enthusiasts site about the classic USA Companies :- Acoustic Research {prior to their current ownership} ; Allison ; KLH ; etc ... , however , in one of the discussion forums in the A.R. {Acoustic Research} section I found several references to a particular technician who is apparently able to repair or restore {when-ever possible} aspects of voice-coils' problems without damaging the original cone {any further than already happened} . Yes , Celestion is British , however their older models' cones ; surrounds ; voice coils , etc ... are similar to those used then in some of the USA manufactured , thus he may be able to repair what-ever may be necessary .

Be wary of accepting new Foam Rubber surrounds for the cones if offered , as these decay with age and exposure to direct sunlight , etc ... faster than solid Rubber surrounds , which I think is what Celestion used for the woofer in the Ditton 66 , or perhaps it is an impregnated textile suround - I have not seen for a long time and have forgotten - what does the surround look like ?

Some of the vintage enthusiasts want foam surrounds in the repair because they hope to get the same suspension Compliance as the original and thus the same in-cabinet bass Resonant Frequency , but this will not be applicable to your case .

I have forgotten all the Links from that web-site - there could be several repairers to enquire of .

I'm disapointed that Celestion didn't reply - I had thought they would want to maintain the reputation of their famous Company .

[sba]

Alan,

Yes.....the Celestion Ditton surrounds are rubber......and, agreeably, I don't think that many foam surrounds would be intact after 33 years.

Also, thanks for reminding me to carefully check the voice coils.....It's easy to imagine a speaker being damaged by an amp, and to forget that a damaged speaker can really put a heavy strain on an amp.

I tried to go to the classicspeakerpages.net web page, but had no luck. I'll keep trying.....maybe they ran out of bandwith with their web-host. I'll also try again on a different computer.

[alan-1-b]

I got to the site just now OK . Try typing in the address , rather than relying on the Link in my post to connect . Typing it in works on some computers , but not all - unfortunately !

Let us know the condition your ebay pair of woofers are in when you get them ,
here's hoping , Alan .