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Old 9th November 2007, 04:40 PM   #161
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Thank you, Grahame, I will try these approaches over the weekend.
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Old 11th November 2007, 09:24 AM   #162
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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:

Click the image to open in full size.

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/RWTomkin...02659903116402

http://picasaweb.google.com/RWTomkin...02677082985602

http://picasaweb.google.com/RWTomkin...02694262854802
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Old 11th November 2007, 07:42 PM   #163
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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
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Old 11th November 2007, 11:17 PM   #164
sba is offline sba
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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
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Old 11th November 2007, 11:36 PM   #165
sba is offline sba
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*
It took this poor chap two years of window shopping before he bought his 66s !!!

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

(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.....
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Old 12th November 2007, 07:43 PM   #166
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Quote:
Originally posted by tonedef2
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.


Quote:
Originally posted by sba
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.


Quote:
Originally posted by sba
It took this poor chap two years of window shopping before he bought his 66s !!!

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

(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!
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Old 12th November 2007, 08:16 PM   #167
Grahame is offline Grahame  United States
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Quote:
Originally posted by rwtomkins

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.
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Old 13th November 2007, 08:34 AM   #168
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Quote:
Originally posted by Grahame


Better yet use the "Download Photo" link in the panel on the right and you'll get the 1129x1600 original.
Doh!
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Old 24th December 2007, 12:31 PM   #169
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Default 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
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Old 24th December 2007, 02:39 PM   #170
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Default 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.
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