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Old 2nd November 2011, 04:16 PM   #831
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Join Date: Jun 2007
Hello everyone

I hope its ok to jump into this massively long, but very informative thread. It took me a fortnight to read through it all but I'm so glad I did. I know I'll have to re-read at some stage as I'm just a novice really and a lot of it went over my head, but it has re-kindled my interest in DIY and I'd like to say thanks for that especialy to Mr Alan-1-b, as without his continued contributions and patients I think it may not have lasted as long as it has.

Anyway, here's my reason for posting
Having seen the circuit diagrams of the ditton 33 and the 44 on Page 25, post #246 & #247 of this thread I was surprised to find they were so different. I thought the 33 & 44 had the same tweeter & midrange drivers and thus would have the same filter circuits, except of course for the different bass drivers.
I have some Ditton 33's which had the tweeters replaced with Morel's of type Cat298. I have never felt totaly happy with these even after fitting 1.7 ohms in series and 10 ohms in parallel with the output from the treble crossover to reduce its output a bit.
Having read this thread and being re-motivated I want to change the tweeters for the Seas HO737 and also update/upgrade the Caps on the crossover board. I think my bass output is disproportionately louder than the other drivers so I'm hoping new caps will improve this situation.
Initialy I just want to replace the existing caps with similar but new electrolytics. This (hopefuly with your guidence and advice) is so I can adjust any treble filter components 'cheaply' if necessary to accomadate the HO737. Then at a later date upgrade to polyprops once it is successfully integrated into the system.

As I live in the UK, What would you recomend as a suitable replacement for the original caps? - which are all black with red tips and mounted on a PCB.
When I fit the seas tweeters will I need to alter any values of caps or add any resistance in the filter circuit, or would they be a suitable match by themselves?

Any advice greatfully appreciated.

Regards
Roy
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Old 2nd November 2011, 04:50 PM   #832
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Location: Boise, Idaho
Did all you Celetion fans see that a guy in England sold a pair of NOS in-box, Celestion Ditton 66 on E-Bay for GBP 1,170? (US $1865)? Plus GBP 250.00 shipping, which looks like it was intended to cover freight to USA. Not sure if the buyer was US or other. I've never seen a set go this high!
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Old 2nd November 2011, 10:29 PM   #833
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Quote:
Originally Posted by tojohndillonesq View Post
Did all you Celetion fans see that a guy in England sold a pair of NOS in-box, Celestion Ditton 66 on E-Bay for GBP 1,170? (US $1865)? Plus GBP 250.00 shipping, which looks like it was intended to cover freight to USA. Not sure if the buyer was US or other. I've never seen a set go this high!
What amazed me was that a) these were obviously not NOS at all but simply in good condition for their age, b) that the guy's last sale got negative feedback and c) that these weren't even late model 66s but the very earliest ones with the black fronts.

Mind you, a few days earlier, a pair of blackies that looked as though they'd been excavated from a tip went for £510. It makes you wonder what a good pair would go for.

Anyway, in response to Royville's post, hello and welcome to the enormous thread. I hope you get some good advice - unfortunately it won't come from me because I'm one of those who's usually asking the questions rather than providing the answers!
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Old 2nd November 2011, 10:41 PM   #834
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Default Good follow up! Thanks!

Thanks for the details! I think owners will agree that $1850 is STILL worth it given the sound quality vs other options.
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Old 3rd November 2011, 01:58 PM   #835
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Guess I sold mine for less than what they might have gotten! (500 CA). With refurbished xovers. Check this thread now & again to see what new might occur.
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Old 8th November 2011, 04:22 PM   #836
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Default Components in Ditton 33

Hello everyone.

I apologise that I will again have to be brief, and thus only can deal in part today with 2 issues.
.
Quote:
Originally Posted by goalhanger View Post

I have Ditton 33s which on have just replaced the caps
and "royville" posted:

"Having seen the circuit diagrams of the ditton 33 and the 44 on Page 25, post #246 & #247 of this thread I was surprised to find they were so different. I thought the 33 & 44 had the same tweeter & midrange drivers and thus would have the same filter circuits, except of course for the different bass drivers.
I have some Ditton 33's which had the tweeters replaced with Morel's of type Cat298. I have never felt totaly happy with these even after fitting 1.7 ohms in series and 10 ohms in parallel with the output from the treble crossover to reduce its output a bit."


Hi goalhanger and royville,

I suspect at least one, and perhaps more, of the components' values shown in the hand-drawn schematic for the Ditton 33 shown in #246 on Page 25 is a mistake.
In the midrange bandpass filter, the Series connected inductor which forms half the high-cut filter is highly unlikely to be 2mH.
I think the 2mH is likely to be the other inductor in that section ... in the Parallel arm of the low-cut filter, and the Series inductor is more likely to be 0.6mH as it is in the circuit for the Ditton 44 which may have the same mid-cone driver.
Also, the tweeter filter - I can believe the 12uF and 0.14mH, but 8uF for the input cap seems too large ... but it could be correct, depending on the Impedance of the HD1000 tweeter - which I do not know.
What did you two find actually printed on each of the capacitors in your 33s ?
- and is there anything printed on your inductors ?

One of you does not have working HD1000s but if any reader here does, please measure the DC resistance of as many samples as you can and Post here so that we can assess what needs to be taken into account when modifying the crossover to close to optimum for other tweeters with different Impedances.
That Morel tweeter is not bad, though it has higher Sensitivity than the old HD1000 thus will need an L-pad to match it to the circuit,
and to calculate optimally for that we do need to know the Impedance of the HD1000 if the 0.14mH inductor is to be kept in that section.
1.7 and 10 ohm resistors may not be the optimum for the L-pad for impedance match to the circuit.

Similar is the case if modifying to accomodate the SEAS tweeter there.

Is that midrange cone the same diameter as the one in the Ditton 44 ?
I have only a very small photo of a 33 here - the cone looks same diameter as in the 44, but it could be 1" less.
There was apparently 2 different versions of the mid-cone used in the 44 - one for each of the 2 vintages of models.
More on this later, but for now please Post whatever you can about the above.
.
*** *** *** *** ***
.
And to the gentlemen enthusiasts who posted above on this page !
:
The Ditton 66 is a very good loudspeaker, but ebay selling prices have reached the ridiculous because those old drivers, particually the mid-domes, are unlikely to be in good enough condition in most cases to be worth that.
For less than that recent sale's amount of money a similar sized loudspeaker could be designed and built with modern drivers to give similar sound to a 66, and better than the apparently not-as-good 662 {and 442, etc ...}.
I think there is a bit of a Fashion-Craze for 66s currently, and I hope what I have been contributing in this thread about re-conditioning them has not been part of what has caused people to bid so high.
I do understand the wanting of a speaker with that type of sound, and obviously few if any current manufacturers have models to satisfy those enthusiasts, but one should be reasonable and consider the service-life of what one is paying for.
.
*** *** *** ***
.
I'll get back here when I can, and hopefully continue with other things in this thread then.
__________________
Alan

Last edited by alan-1-b; 8th November 2011 at 04:38 PM. Reason: to add two paragraphs, and correct some spelling !
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Old 10th November 2011, 01:42 PM   #837
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Default xover appears correct

Hi Alan,

I’ve thoroughly checked the 33 crossover circuit against my crossover units and it looks totally correct to me. I can’t confirm the value of the 2mH inductor but it is physically the largest one on the crossover and it is drawn in the correct position on the circuit of ‘#246 on Page 25’. Is there a way to measure these unknown inductors? (I only have a scope, Fluke 87 and PC at my disposel).
Also the 8uF cap in the treble circuit is correct. What I would add however is the fact that both the 8uF and the 12uF caps in the treble circuit are marked ‘LL’ which I assume means Low Loss. All component ID’s on the drawing appear correct also.

I now think the midrange cone is different from the one in the 44. The 33 mid looks very similar to the ‘Kef B110’ Mid/Bass unit. From edge to edge it measures just over 5 inches (13cm) and has a ‘pressed’ metal frame whilst the 44 mid appears to have a cast metal frame. I will try to post a photo in a day or two if this will help (working 12 hr nights at present). In the 33 drawing the capacitor which is across the midrange unit has a value of 16uF (could be miss read as 18uF on the drawing).

Hope this is useful

Regards
Roy
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Old 12th November 2011, 02:05 PM   #838
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Location: Midlands
Default For Ditton 33 go to

Hi Royville,

and to any other Ditton 33 owners who have found this,

for continuing discussion about the Celestion Ditton 33 go to:

Crossover nightmare!!!!!!!

which, if the above does not work as a Link, is a Thread titled:

Crossover nightmare!!!!!!!

started by:

lorienblack
,
and there we are currently up to Page 20, #198 for new posts.
*
I prefer to discuss the Ditton 33 there, and not here,
because it is not much like the Ditton 66, thus out-of-place in this thread,
and as we will be discussing its crossover which is currently part unknown to us it is more relevant to some discussion in the other thread,
and I hope there some Ditton 44 owners may be able to provide information about the 33 also.
*
Royville,

I will Copy your above reply in part and Paste it in the Crossover nightmare!!!!!!! thread,
and reply there, so go there now.
__________________
Alan
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Old 7th January 2012, 10:07 PM   #839
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Hello I own a pair of Ditton 66 serial 1 for nearly one year. It's great, unfortunatly I heard through MD500s rarely a strange sound specially piano playing.

I found a workshop in France close to Paris that fits the problem ! now it runs very well it was expensive to my wallet but coil varnish and glue are a recent type, and he applied a black liquid to the horn
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Old 21st February 2012, 02:35 AM   #840
reggie is offline reggie  Australia
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Default Morel EM 1308 v MD500

Hello to you all. I wonder if anyone on this thread ever got round to fitting alternate mid-range drivers to their 66's. I know I saw it mentioned in a thread somewhere but cannot find it again. I'm actually thinking of the Morel EM 1308 dome(s) for my early model (1975 - black fronted) Celestions in lieu of the MF500's. There is no reason to change other than (a) the MF500's are now 37 years old and nothing lasts forever (b) I will be building new Xovers and (c) I think I want the change. It's either that or I have a go at building Troels diy TQWT speakers. I've actually swapped around several dome tweeters (no-name German dome, Seas dome and Hiqaphon and really, to my partially deaf 63 year old ears the sound did not change at all. So, while I'm not expecting to hear much of a change with the Morel I am hoping for a bit more clarity with voices in the mid-range. Also, by the by, when I purchased my Celestions they asked me whether I wanted to buy the optional steel stands (shaped like the outline of a kitchen chair) which raised the Celestions up about 8 inches and tilted them back maybe 5 degrees or so from the vertical. I couldn't afford it then. I have actually seen a picture of the 66's on these stands in an Ebay advertisement some time ago. Food for thought. Anyway, hoping to hear from someone who has done/listened to some experimentations with mid-range drivers.

Reggie
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