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Mr_White 29th December 2006 07:18 AM

celestion 66 needs Mid-range
hello hopeing someone can help me , i have 2 celestion 66's very old but i love them , i need a new Mid-range speaker i think its a MD500 not to sure , ill have to take it out to be sure , i had it out just looking for loose wire's but no luck , anyone know where i can find one ? :bawling: its sad to see them like this

tonedef2 20th January 2007 09:29 PM

Impossible to find, i have a set of the 66's and i will never get rid of them........

I have resored my MD500 myself completely disasembling the entire, coating etc.

I got to say WoW........


This was alot of work but well worth it, it is very delicate work and if you make a mistake it's over ;-).

I also found NOS stock diaphrams for my 2000's tweeters....lucky.

This speaker is a very rare and sounds BBC +
Family are professional musicians.........they would agree....

If you need some advise i'll try to help!


tonedef2 10th March 2007 10:07 PM


Did you solve your mid driver issue in your 66's ?

I will take your broken mids off your hands if you still have them?


Grahame 11th March 2007 12:30 AM

Hi All,

This thread / forum is just what I've been looking for.

I grew up in the prescence of a pair of Celestion 66 Studio Monitors, thanks to my father being an audiophile (my mother still has them).

I was lucky enough to aquire a pair second hand in the late eighties for the sum of 100 pounds - I was visiting my father and he had noticed another pair for sale in the local paper. I had to have them - the previous owner had to let them go as his wife had said they were "too big". They have followed me around ever since - even here to the USA - and I haven't felt inclined to change them.

Recently I've noticed a "buzzing" on one of the mid range drivers , on certain tracks / material , at moderate to loud levels. Low levels seem to be ok, thankfully.

After much research I've ended up here. I've had a look for obvious failures, re-seated wires / swapped drivers between speakers etc.

Looks like I have the same MD-500 issue as tonedef2.

Is it an age related issue (the interior of the cabinet shows a build date of 1970! - almost as old as me :) ) ? - I ask as I've just seen some NOS MD-500's on ebay - for more than I paid for the speakers.

Being a cheapskate at heart - what are my options?
Is it likely that the issue will occur on all drivers?

Is it worth replacing the crossover + wiring - or just a mechanical issue with the driver.

Your thoughts are welcome from a fellow brit ex pat 66 lover.


Your thoughts are welcome.

tonedef2 11th March 2007 12:43 AM


Well search my other posts, i no longer have the problem! ;-)

Read those before i say anything else.......
Yes i have owned mine for 23 years too! love these things.
Anyway read my other posts.....yes your buzzing is the classic failure, gets worse as the volume goes up.


Grahame 11th March 2007 01:56 AM

Hi tonedef2,

I've searched all your other posts, and it would appear the solution to my problems is, ulp, to re-build the MD-500's. :(

When investigating the problem, I got as far as removing the faceplate (taking driver out of cabinet, removing collar / speaker guard - essentially unscrewing any visible screws )

A 500Hz reference tone from Alan Parsons "Sound check" would get the buzzing going nicely, in a repeatable manner as you raised the volume. Placing a finger gently at the edge, between the dome and the metal casing would calm the resonance - not a general solution.

I was not inclined to investigate further, as I was not confident that anything else I tried would be reversible!

How complex was the rebuild? What tools did you need? How feasible for a layman?

It looks like you are my only hope!


tonedef2 11th March 2007 03:32 AM


Stop! do not power them with the large plate unscrewed! Coil insulation is a question and can short your amplifier under certain conditions…

Well I’ll type up a guide in the next couple days ( time permitting) and add some pictures I took as well.

From what I learned in this process, on this design, even NOS stock will fail as well due to the type of glue and application.

Note: This process is not for the faint of hart my custom jig was trial and large 7 inch mag/light was a must have....
For one example, material had to be trimmed as over time it had stretched; very scary work as there is a cancellation dome with little margin right behind the second dome stage.
I believe you have the first gen of the 66’s?

If you have a digital camera to take pics of how bad yours are, this will help....

O and yes my mids are very very nice now……..well worth the work!
I must admit I do love the “tuned by ear” sound of these, very happy my family kept them for me………

Until later...I may hire myself out for this but I am short on time these days and well you know…’s a lot of work and time consuming in the sense of waiting for material to form shape, product to cure etc…………………

Anyway I will endeavor to help you.

Grahame 11th March 2007 09:02 AM

Many Thanks in advance.

Yes, I think I have the first gen 66's ( I've seen some 662's on the web with two piece cover). Mine has HF 2000, MD 500 , 12" + passive radiator , all in vertical line, single piece grill / cover for cabinet. Big Thick Cross over circuit board , complete with signed off QA sticker! +

"Celestion | 66"
"Studio Monitor"

Badge at top of cover.

Serial # 116400 on back.

I'll wait and see if its something I feel capable of / comfortable with, when I see your step-by-step.

Judging by what I found when searching on the web, many others may have this issue, as the MD-500s start to reach end of original life. Who could have envisioned that when they were built, 30 - 40 years in the future, they would still be going strong? and still be loved?

Thanks once more, for sharing. At least I know there is hope.

Your help is greatly appreciated.

Graham Maynard 11th March 2007 09:29 AM

Bought mine in 1973; no serial numbers !
Did not like the 'honky' dome sound, much prefer cone.
Took the midrange domes out soon after, and dropped in 6.5" full range.

Tweeters very fine though.
Bass drivers good; nearsest I've come across is Monacor 300 with 18Hz Fs.
Don't like ABR sound, not well enough controlled even when amp has very low output impedance.

Graham Maynard 11th March 2007 09:39 AM

How many Ditton66 threads are there ?

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