Celestion 66 needs mid-range

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Grrr! I've spent the whole weekend on this - well, seems like it - and I still can't successfully post the images I want to post. I do everthing you're supposed to do with the vB code but the images just come up like this:

An externally hosted image should be here but it was not working when we last tested it.


If anyone can tell me what I'm doing wrong I'd very much like to hear from them.

Meanhwile, here are links to the images showing three pages of data on the Celestion 66s, including the circuit diagrams for the wired crossovers (first page) and PCB crossovers (last page):

http://picasaweb.google.com/RWTomkins/Celestion66Data/photo#5131302659903116402

http://picasaweb.google.com/RWTomkins/Celestion66Data/photo#5131302677082985602

http://picasaweb.google.com/RWTomkins/Celestion66Data/photo#5131302694262854802
 
Hello everybody,

(quote from rwtomkins) >

(I also have a question on the mid-range speakers, which after all is where this thread started. When I got my 66s one of the mid-range units had what looked like a rubber band lying unattached to anything behind the speaker's little metal grill. I was afraid to touch these units so I gave them to Wilmslow Audio to have a look at. They said they'd put the ring back in place but on checking the other unit they'd found it was completely absent - but not to worry about it because it didn't seem to make any difference.)



Hello all, I've been away.....

Alan/sba/graham> I see we have made great progress on the crossover, how about a shopping list of brand & values/types for a direct drop-in cap upgrade> Alan?

I would like to thank you all aswell!

rwtomkins> Was it black or white-ish? wide? Even? Please read my other post regarding our MD500'S…..I believe they have mis-informed you…..see my other posts, not may folks have seen how these where built, it is different!

News: I have worked out a nice fix for the defraction issue, with 2 options for with or without grilles, im making my final version soon and will post pics and how-to's (yes it also adressess the top lip issue!

ToneDef2 / Pete
 
Good stuff rwtomkins!

This confirms that both the small dust cap woofer (T1600) and the large dust cap woofer (T2619) were used in the 66. I wasn't sure, because my single T2619 replacement woofer came from a Ditton 44.

It also confirms that Celestion was playing around with the capacitor values in the midrange....one diagram shows 24uf, and the other seems to show 30uf (24 + 6), if I'm reading the diagram correctly. One of my speakers was also outfitted with 28uf in this same location.

Thanks for the phone number for DK loudspeaker rebuilding...I hope I won't need him!


sba
 
*
It took this poor chap two years of window shopping before he bought his 66’s !!!

******************************

(from the Boston Audio Society Newsletter, August, 1977)

Western Technologies Reference 2S Loudspeaker--

It is always satisfying to see a worthwhile audio product come to the market through the energy of a dedicated music lover. Darrell Spreen is such a man, and his company Western Technologies (9819 McKnight St. N.E., Albuquerque, NM 87112) was formed to offer the Reference 2S speaker system to audiophiles. A systems analyst involved with laser research for the Air Force, he has spent the past fifteen years designing, building and evaluating loudspeakers in his leisure time. During a two-year search for a commercially available speaker for use in his home (he decided on the Celestion Ditton 66), he developed a hierarchy of qualities he felt important for speakers to possess. An outline will complement my review of the Ref 2S, as his design goal was to achieve as many of these qualities as possible in the final product. The level 1 qualities are those which Darrell feels contribute to a speaker's accuracy; they include bandwidth, balance and smoothness. Level 2 qualities, low distortion and definition, result in transparency of sound. Those of level 3 are rare among speakers and contribute to real- ism of sound. They are musicality, depth and three-dimensionality, delicacy and aliveness. In designing the Reference 2S, he addressed level 1 and 2 qualities first. He then sought those of level 3 through a lengthy process of building many prototypes and comparing them both to the Celestion 66's and to a planar-magnetic-design speaker. Throughout all of this, he kept in mind the objective of building a modestly priced system.....
 
tonedef2 said:
rwtomkins> Was it black or white-ish? wide? Even? Please read my other post regarding our MD500'S…..I believe they have mis-informed you…..see my other posts, not may folks have seen how these where built, it is different!

From memory it looked like a rubber band, the old-fashioned, thin, light brown ones but I suspect the cross section was circular. It was encased in fluff and stuck behind the metal grill so I didn't really get a very good look. But the bloke at DK Loudspeakers also said not to worry, he said it just went between the grill and the body of the unit and didn't do anything useful. However I certainly will read your other posts.


sba said:
This confirms that both the small dust cap woofer (T1600) and the large dust cap woofer (T2619) were used in the 66. I wasn't sure, because my single T2619 replacement woofer came from a Ditton 44.

It also confirms that Celestion was playing around with the capacitor values in the midrange....one diagram shows 24uf, and the other seems to show 30uf (24 + 6), if I'm reading the diagram correctly. One of my speakers was also outfitted with 28uf in this same location.

Yes indeed, on both counts. I have the same diagrams for the Ditton 44 and they confirm that the same woofers and tweeters were used, with the same part numbers, in the 44s and the 66s. And yes, they do seem to have added 6uf to the PCB crossover.

To compare the circuit diagrams, it's probably easiest to right click on the images in Picasa, copy them, paste them somewhere else and print them out. Btw, I did work out how to insert images in a post eventually, but I thought it might eat up less bandwidth if I just left the links as they were.


sba said:
It took this poor chap two years of window shopping before he bought his 66’s !!!

******************************

(from the Boston Audio Society Newsletter, August, 1977)

Western Technologies Reference 2S Loudspeaker

Yes - and then he proceeds to use the 66 as his reference for developing the perfect speaker! :)
 
rwtomkins said:

To compare the circuit diagrams, it's probably easiest to right click on the images in Picasa, copy them, paste them somewhere else and print them out. Btw, I did work out how to insert images in a post eventually, but I thought it might eat up less bandwidth if I just left the links as they were.

Better yet use the "Download Photo" link in the panel on the right and you'll get the 1129x1600 original. Thanks!

Given we the circuit topology, and the component values, I'll see if I can stick them in some speaker/crossover software and see If I can get some "theoretical" plots. And we should be able to see what the difference the designers were aiming for.
 
Ditton 66

Thanks everyone

- especially to Tonedef2. Most impressed with skill in rebuilding the MD500 and HF2000!

I need to repair/replace one HF2000 in my Ditton 66 Mk I so would you tell me source for diaphragms. I guess need to replace both, so they match. Please tell me the nominal impedance too. (One option would be to buy the Coles 4001, certainly would cheaper than some recent auction prices. They look slightly different.)

Any idea what difference to HF2001 that were used in Ditton 662 (maybe just different efficiency/impedance).


I would welcome your help if you can provide details of crossovers for Mk II and 662. (I can provide a diagram for the original Mk I crossover if that would be of interest. The Mk II benefitted from a Linkwitz-Riley crossover which had steeper 24 dB per octave filters ) I wish to renovate my crossover with new capacitors, so thought it would be better if I adopted a later version of the crossover.

thanks for help
 
Linkwitz-Riley

Hi again

Thanks for datasheets. Mine are blackies and I guess woodies are Mk II.

Maybe the 662 uses Linkwitz-Riley, or maybe my source got it wrong entirely.

Q3:
When you insert new metalized poly caps, was the balance OK without inserting padding resistors to allow for difference between new style caps and the old electrolytics?

Q4:
listprice for Sonicaps $500. Any cheaper source at this quality?

PS:
I hear that paralleling caps with Vishay small value caps (are cheap) improves the sound; worth a try.
 
Hello all. First post.

I just bought a pair of 66 mark 1s from Fleabay. They haven't arrived yet so I don't know what state they are in.

I got them to replace some ESL63s I have recently sold. Why sell ESLs? I had endless trouble with them as my house is very old and a bit damp for them. I got fed up replacing the mylar diaphragms. I remember hearing Dittons many years ago and being impressed.

It'll be interesting to see how they compare to ESL63s with some open dipole subs I cooked up.

I have a selection of amps to use with them but plan to use them with a 211 valve amp I built a few years ago based on Audio Note circuitry - except I just plugged it in and it fried the mains transformer. Bummer. That'll keep me busy rewinding that. It provides awesome bass when it works so I'm looking forward to trying it with the 66s.


Anyone use valves to drive 66s?
 
Ditton 66 crossover

Hi Phil, I'm a newby too.

The Celestion is known for a full bass, so placement near wall or corner may "boom". High efficiency and an easy load to drive. I recall it having an open and clean character, however that was 34 years ago with fresh capacitors!

Comparing the crossover diagrams for the (earlier) tagged crossover board and pcb crossover, it appears that initially 30 mF series capacitance was in the first leg of the mid-section, later reduced to 24 mF. Effect: rolls in the mid unit slightly higher in frequency, removes it further away from its fundamental resonant frequency so allowing it to handle higher input levels generally. A minor alteration.

I conclude that these crossovers are already Linkwitz-Riley crossovers. The bass section appears to be classic "Linkwitz-Riley". Yet as the mid unit has a natural acoustic roll in and roll off so single 12 dB/octave sections were used for the mid. The tweeter has a natural roll in so only a 1.5 section has been used of 18 db/octave for the tweeter (note the unit is connected with inverted phase). [cf. 4th order 24 db/octave Linkwitz-Riley crossover requires units to be wired in phase. ]

Still, am interested in any changes made for the 662 model - although am unsure whether those dynamic drive units were the same as to efficiency & impedance. Physically they appear the same. (Crossover values are unaffected by the new ABR and change in cabinet volume - if any.) I saw a photo of a 662 crossover with about similar number of components and the same number of air-core inductors (5), suggesting that the design was hardly different if at all. Maybe 662 was just a re-styling of the 66?
 
24mF or 28 mF or 30 mF

On reflection, Celestion may have been custom tuning the speaker to change the level of energy balance between mid and bass, allowing for component value fluctation.

So when replacing capacitors, it may be worth doing likewise to tweek the crossover until the sound is most similar between the pair, and preferred overall balance.

Just a thought.
 
Solen capacitors

Found an HF2000 from a Ditton 44.

Played the 66 Mk1 in unaltered state today - for the first time. Like the sound (no nasties at all) yet feel upper frequencies are a bit cloaked so ordered the replacement capacitors.

Thanks for mentioning the Solen sale. Most reasonable - complete cost ~ £65 including VAT and air freight. Bought extra 1.8mF 2.4mF to tweak if needed.

Will replace the skinny internal wiring.

Delayed sound radiates from the cabinet itself which makes the sound less precise, although contributing some of its "warmth". So also considering lining the cabinet with one or more layers of Dynamat Xtreme (or Dynamat Extreme) to reduce panel vibration - starting with opposite the bass unit, but also the sidewalls.

How are your other 66s sounding?
 
Re: Solen capacitors

harnfield said:
How are your other 66s sounding?

I actually seem to be getting less bass out of my mine (very late model woodies, with PCB crossovers) than from the Ditton 44s they replaced. The 44s were on spiked feet (concrete floor) and I'm wondering if this explains the difference. Anyway, I'm trying to find the time to experiment with different configurations - I still have the 44s as a reference.

I do love the 66s though. If you get in the right place and listen to the right record, you still get more than a hint of what they are capable of basswise. And truth be told, I probably like more bass than most people would want. Probably the bass I was getting out of my 44s would be regarded by most people as undesirable booming!
 
bass response

I like bass too and prefer the top end to be reserved. This may be called the "American sound". Whereas a gutless bass and prominent top end might be called the "European sound" eg. Philips products (according to the preferences of those markets).

The 66 is called Studio Monitor because (when new - with fresh capacitors) tonal balance was naturally distributed by reference to subjects like classical orchestras, was capable of the full dynamic range without blowing the units, was durable to be carted around a bit, easy impedance to drive, and had tolerably low levels of distortion (probably with that ranking).

I used excellent preamp & CD player and a Musical Fidelity amplifier which can drive ANY load and so deliver the full bass signal. Music listened to: second track of Sarah McLachlan's "Surfacing"; Bach organ music; "29 Palms" from Robert Plant's "Fate of Nations"; piano recordings; Joni Mitchell. The low end was natural and present although possibly a tad less full than from my Apogee Acoustics "Scintillas".

I doubt that the 44 would reproduce the shuffling audience noises and organ pipe breath, or the subbass from Sarah McLachlan's track, as much or as effortlessly as the 66.

An infinite baffle design, the response from the 44 must drop sharply below 40 Hz whereas the 66 is a form of bass reflex with the ABR tuned to extend the response lower while alleviating the woofer cone movement, hence handling of greater volume at lower levels of distortion. Probably the 44 has a resonant hump around 80Hz which feels energetic and punchy, and were it to have a hump around 300Hz then it will sound good with rock music I believe. This may be verifiable from inspection of the frequency plots, were they available.

Perhaps the 44 is more efficient and produces a louder sound than the 66 for the same input. I see that the bass section of the crossover is identical in both, however the 44 has solid core inductors and the 66 has air core. Solid core have lower impedance I believe although they introduce some distortion. On the other hand the larger cabinet assists efficiency of the 66.
 
Finally back, for a while ...

Hello all, and welcome to the recent new contributors to our discussion :-
rwthomkins ; harnfield ; PhilPrice ,
and thankyou for your comments and contributions,
especially to rwthomkins for the data sheets for the two versions of the 66s !
- information on these confirms several things that others have time-consumingly found in their 66s, and clarifies some variations between Mk I and Mk II versions.

I have been away and mostly working in a rural area where I do not have computer access, thus why no comments from me for a while.

I apologise that I have not yet answered still a few questions from earlier, and now I have read the interim posts I see several new points to comment on, though I won't have time to get through all those today, but hope to before too long.
 
replacement Capacitors - brands

tonedef2 said:

Hello all, I've been away.....

Alan/sba/graham> I see we have made great progress on the crossover, how about a shopping list of brand & values/types for a direct drop-in cap upgrade> Alan?


ToneDef2 / Pete

Sorry it has taken me so long to get to this Pete, and to others who may be interested in what is worth spending money on.

The basic reasonable quality metalized polypropylene cap is made by Bennic.
These are used by several manufacturers, including B&W in apparently all except their very most expensive models {where-in they apparently use the expensive Mundorf caps - at least to their tweeters, and probably to their midranges in those 3-way models}.

The Dayton branded caps are apparently made by Bennic.
Bennic will manufacture for any large quantity customer.

Solen are quite good quality, and sound a little different to Bennic - some DIYers prefer Solen and some prefer Bennic.
These sonic differences are likely decided with preference given to the users' preferred drivers specific sonic characteristics.

Axon or Aeon {Latin letters versus Greek letters used to spell the same word} may be made by Solen, though I have not confirmed this.
Their sonic preferences seem to be similar to those I described above.
One user stated they sound a little different to Solens.

Next level up in sound quality is ClarityCap PX series, and at only a little higher price than the others above.

I am not familiar with Sonicap, but they seem to have fans amongst various users in various places one can find via web-searches.

Similar price range to Sonicap is Kimber.

I would not go above this price range in restoring the Celestion 66 until I had heard the benefits of what I had achieved with whichever of the above caps, and thus assesed their potential further., as next price level is quite expensive !

About specific cap values/sizes next time - got to go now .
 
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