Celestion 66 needs mid-range

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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
 
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 unit....re-glue, coating etc.

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

THE USED REPLACMENTS U MAY FIND WILL BE DEGRADED TOO...


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!

cheers
 
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.

Regards
Grahame

Your thoughts are welcome.
 
Hello,

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.


TonDef2
 
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!

Grahame
 
Hello,

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 error...my 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…..it’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.
 
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.
 
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.
 
To graham

1-Well first I disagree regarding the sound of the 66’s, in fact yours may have had other issues……..there are really 3 versions of the 66/662 line, orig 66 line like you 2 have, then the 66 second gen like I have, then the 662 line which was very different again!
The first gen 66 used a MF500 at reduced watts…
A far as the bass goes you’re the fist person to say the bass is somewhat less……….these 66 have some of the best bass available, that being said I mounted spikes on the bottom and I just cant remember hearing any better bass out side of live…….

To all

2-Note to all: im looking for the second version of 66 crossovers…for experimentation…

To Grahame

3-Do you have a digital camera? Reason why im asking is it’s much easier to show you than to produce a complete step by step…
Do your 66’s have black baffle board or finished wood?
Do your crossovers look black and red? Paper cap types used?
The other guy’s honk is what happens to the earlier version when everything fails together, but I know what he’s saying…


TonDef2
 
Hi tonedef2.

Bass on the 66s I liken to -
never mind the quality feel the (band)width.

Someone else thinks like me with their Celestions -
http://www.diyaudio.com/forums/showthread.php?postid=1113479#post1113479

The bass goes low, and for their time was powerful and great for parties and discos in a large room, but it is not SQ accurate for home hi-fi. There is quite a timing delay at low frequencies and it stands out as error when compared to other properly damped low Fs bass drivers. Once you recognise the bass phase/timing error it becomes annoying because you can't get rid of it; it is caused by the ABRs.
 
Hello,

We need to keep the 66's within context! I'm not comparing these to xx,xxx.xx speakers, and yes I have heard better low register reproduction, as I mentioned as well they do need spikes, and the delay phasing is really quite minimal, again keeping the speaker in context, you would agree one would need to spend a lot to do better than a restored pair of these, they do have a unique sound tuned by ear not computer......anyway for 500.00 try and find a 18-40 frequency unit......these process a real nice tone you will not find on your flat graph! If only we all heard like a flat graph, then making a speaker would be 1, 2, 3 ………

Thanks anyway im just trying to help the other fellow out, not join in a subjective/objective speaker debate.

Remember my name TonDef2 what’s that mean to you? lol
 
Chaps,

Lets keep it on topic!

I like the way mine sound, I'd like to keep it that way.
Other people may be in the same position as me.

Back to the topic at hand

Yes, I do have a digital camera (but I'd like to know what I'm letting my self in for , before I start)


Hopefully these pics will answer your questions on cabinet construction / Crossover layout. The Crossover is mounted on the cabinet wall behind the 12" woofer.

Picture link.
http://pg.photos.yahoo.com/ph/spam4ga/album?.dir=/3e1ascd&.src=ph&.tok=phxVyaGB3aQJUz.T

Its been a, er, "few" years since I knew what L, R, C meant in physics, but I make that 5 inductors and 8 capacitors (L1-5, C1-8)
 
Hmm,

The multi meter only measures resistance in Kilo Ohms!,
Time to treat my self to a cheapo digital multi meter I think.

Any one have any recommendations - given that I think I'll want to measure results in the 4-8 Ohm range?

This looks like it could be fun.
 
What do you do with your kilo Ohms? heh. Electrical engineer?
We are not measuring this under load.........DC resistence/continueity only. How this speaker behaves under variable loading has been worked out by the designer......

Any cheep one will work, or just swing them by a car/stereo store.
See if we have burnt coils first... we don’t want to be restoring paperweights....

This is hard since I cannot inspect these speakers, but do you know how to look test for vulcanization?

ToneDef2

By definition from Ohm's Law, a device has a resistance of one ohm if a voltage of one volt causes a current of one ampere to flow (R = V/I). Alternatively and equivalently, a device that dissipates one watt of power with one ampere of current flowing through it has a resistance of one ohm (R = P / I 2).

Since 1990, the ohm has been maintained internationally using the quantum Hall effect, where a conventional value is used for the 'von-Klitzing constant', fixed by the 18th General Conference on Weights and Measures as R{K-90} = 25812.807 Ù.

The complex quantity impedance is a generalisation of resistance. Its real part is resistance and its imaginary part is reactance. Impedance, resistance and reactance all have units of ohms.

The symbol for the ohm is the Greek capital letter omega (Ù). If the Greek letter cannot be used, the word ohm is used instead. The various guides for the use of the International System of Units do not explicitly forbid the elision of the final "o" of some SI prefixes, although there is nothing in them to suggest that it is allowable, either. As a result, one is just about as likely to see "kilohm", "kiloohm" and even "kilo-ohm", and the same holds true for hecto-, micro-, nano-, pico-, femto-, atto-, zepto-, and yocto-. The only other SI unit to suffer from this kind of orthographic uncertainty is the ampere. In the particular case of the ohm, one even sees the "a" prefixes lose that vowel: hence megohm and gigohm. Higher prefixes are rarely used with ohm. In the other direction, milliohms (or millohms) are seen where the resistance of cables, etc., are measured.

Units of ohms, kilohms (103 Ù) and megohms (106 Ù) are used in electronic design documentation. On schematic diagrams and parts lists kilohms are abbreviated "K" and megohms are abbreviated "M". Thus, 33 kilohms would be rendered as 33K, and 5.1 megohms would be 5.1M. Another commonly used convention is that the multiplier is used to replace the decimal point, so that 5.1 megohms can also be represented as 5M1. This convention is used because a decimal point can be difficult to see in small or cluttered print. Values less than 1K are rendered either (a) without any symbol, or (b) with an "R", following the number; so 680 ohms can be shown as 680 or 680R. Resistors are usually identified by a reference designator, R, and a cardinal number, e.g., R12.
 
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