Celestion Ditton 25 and 44 Refurbs [Archive]

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madders

27-03-2016, 20:20

Hi everyone,

I recently acquired a pair of Celestion Ditton 25s and 44s that need some work. I've seen a few threads on here about these speakers so I thought I'd start one, and hopefully get some advice.

They are both in good condition - the 25s are really good, the 44 cabinets have a few scuffs and scratches.

So I've started by cleaning and re-oiling the cabinets. They are currently drying after a couple of coats:

16544

Something looks dodgy with one of the tweeters on the 25s, but I've decided to concentrate on the 44s first.

I'm really impressed with how these sound. Really full. But there are times when something is not quite right, although it's hard to identify what.

So the next thing I want to do is upgrade the wiring and capacitors on the crossovers (they are the older non-PCB type):

16545

The date on some of those capacitors is 1972 - so I think they are due for a change! I've never done any internal work on speakers before. There's so much conflicting information on what replacements to use (I've spent hours reading through threads on here and other forums). So I'm just going to go for exactly like for like replacements:

For the woofers (the black caps on the right), 72 uF Alcaps.

For the mids (the 6 uF at the top and 24 uF at the bottom), I'm not sure if both these existing caps are low leakage. Does anyone know for sure? Neither has LL written on them anywhere. If they are, I'll probably go for Mundorf ECap PLAIN. The exact values aren't available though, so I'm thinking I'll make the 6 uF with 4.7 + 1.5, and the 24 uF with 22 + 2.2. Or I could get exactly a 6uF Alcap Low Loss.

For the tweeter, I might use ClarityCaps. Does anyone know if they are worth the extra cost over cheaper polypropylenes?

I attempted to remove the crossover board, but I found my trusty 25W soldering iron (Antex from Maplin) was not very effective. I'm wondering if I really need to buy a more powerful soldering iron, or persevere with the one I have, but I don't want to damage any of the components I'm not changing by overheating them.

Any tips or advice would be great!

Thanks!

karma67

27-03-2016, 20:29

hi,
have a look here :)
http://theartofsound.net/forum/showthread.php?40237-modifying-and-recapping-ditton-44-s
take pictures as you go so you have a reference point of each step,you might find the old solder melts easier if you put some flux on it and puts some fresh solder on the old,it will all melt much quicker then.
J.

madders

27-03-2016, 20:53

Hi Jamie,

Thanks! I'll try again with some flux. On some of the connections, there is a lot of solder though!

In your pictures, it looks like you didn't use a low leakage Alcap for the 6 uF in the mid range. Is that correct?

Also, what replacement wire did you use? I like the blue sleeves - looks very smart!

Thanks,
Michael

karma67

27-03-2016, 21:07

if i remember correctly the darker blue alcaps are low loss and i used van damme blue for internal wire :)

DarrenHW

28-03-2016, 08:29

Hi Michael,

Your speakers look to be good examples.

I've tried the DIYAudio mods for the 44's using Jantzen CrossCaps and I've recapped them with Alcaps but now use Mundorf E-Caps with a small Ansar Supersound for the mids, Alcaps for bass (although I will try Mundorfs at some point) and Ansar Supersound for the tweeter (I have used Clarity Caps for the tweeter and found Ansars to be a better tonal fit for the speakers).

My advice would be to follow Ken's work (I know it's for 66's but the same applies to 44's), you'll find the answers to all your questions and plenty of advice here:
http://theartofsound.net/forum/showthread.php?31916-Renovation-of-Celestion-66-Studio-Monitors&highlight=ditton
http://www.jkwynn.co.uk/Project_Images/66/66_XOver.pdf

Wakefield Turntables

28-03-2016, 09:52

Michael,

Just listen to what Darren and Jamie have to say they have probably taken the Celestion speakers further than anyone else.

madders

28-03-2016, 11:26

Thanks guys. For the mids, I'm sill not sure about the second 6 uF cap. On the PDF it is just a standard Alcap, should I go for a low loss one?

What thickness of speaker cable do you recommend? I was thinking about 1.5mm between the crossover and the drivers, and 0.75mm on the crossover.

DarrenHW

28-03-2016, 12:21

From memory I don't believe it's LL. Personally I think there's a noticeable improvement using a Mundorf here, you could use a 5.6 or if you want exact values 3.3 + 2.7.

I too used Van Damme Blue 2.5mm to rewire the speakers although this was a bit awkward soldering to the tweeters, if I did them again I would probably use 1.5mm.

karma67

28-03-2016, 16:49

From memory I don't believe it's LL. Personally I think there's a noticeable improvement using a Mundorf here,

yep agree with you there,i followed kens advice in the pdf, he used 24uf Parallel 22uf ECap + 1uf ECap + 1uf
Ansar PP.
sounds better than the like for like replacement.

sumday

29-03-2016, 19:07

Assuming the cabs are in a raw state, I would recommend using LORD SHERATON CARETAKER WOOD BALSOM.
comes in a small glass jar looking like yellow shoe polish.
its a bit of work polishing out but brings out a nice dull sheen...not too glossy.

oh, the pine scent makes your room smell like a Swedish forest glade.....or summat!!!!

NIGE.

karma67

29-03-2016, 20:19

Lol love the name! I bet it says "feeds wood" somewhere on the tin.

madders

30-03-2016, 00:25

Thanks for the suggestion, I see Wilkos sell it for £1.75. I've already used some Colron teak oil but I'm not impressed with the results and it cost £10! I might redo them.

I ordered the capacitors this morning. Had to order them from 3 different places, so it's cost £15 delivery in total!

madders

04-04-2016, 21:47

It took a lot longer than I expected, but finally finished!

16604 16605

What is the best glue to use when putting the drivers back? I'm pretty sure they were glued in before.

walpurgis

04-04-2016, 21:54

No No No! Never glue drivers in. Use clamps if you have to.

This sort of thing: http://www.ebay.co.uk/itm/BLACK-HEAVY-DUTY-METAL-SPEAKER-CLAMP-/270960784940?hash=item3f1685762c:m:mhzhUSsR2Lt49lo CMidH3pg

There are various types, including plastic ones if you don't want to mark the drivers.

Remember to use gaskets or foam tape to seal them in.

I think what you thought was glue was likely a sealing compound.

madders

04-04-2016, 22:09

Ah ok thanks! I was thinking about glue to seal them (they already have screws to hold them in place so I don't need clamps I don't think).

I'm glad I asked the question because I almost used some superglue!

So if I just get some foam tape from B&Q that should do the job?

karma67

04-04-2016, 22:12

is there not a rubber gasket?

walpurgis

04-04-2016, 22:30

This is perfect: http://www.ebay.co.uk/itm/5m-x-2mm-x-10mm-Safety-Black-Single-Sided-Adhesive-Foam-Cushion-Tape-Closed-Cell-/351675114941?hash=item51e17865bd:g:Ie8AAOSwwpdW4pV W

You'll have to wait a couple of weeks for it to arrive from Hong Kong, but 2mm thickness is just right. In fact I've just bought a roll.

I sometimes buy black craft foam from hobby or art shops and cut gaskets from that. Trouble is, it normally only comes in A4 size. No good for 12 inch drivers.

Oh and if you have screw fixings for the drive units that'll be fine.

madders

04-04-2016, 22:50

is there not a rubber gasket?

I just looked at the back of one of the woofers and there is a foam gasket - I didn't notice it before - it's pretty squashed. There is a faint ring of something round the hole though, so maybe it was sticky on both sides before.

This is perfect: http://www.ebay.co.uk/itm/5m-x-2mm-x-10mm-Safety-Black-Single-Sided-Adhesive-Foam-Cushion-Tape-Closed-Cell-/351675114941?hash=item51e17865bd:g:Ie8AAOSwwpdW4pV W

You'll have to wait a couple of weeks for it to arrive from Hong Kong, but 2mm thickness is just right. In fact I've just bought a roll.

I sometimes buy black craft foam from hobby or art shops and cut gaskets from that. Trouble is, it normally only comes in A4 size. No good for 12 inch drivers.

Oh and if you have screw fixings for the drive units that'll be fine.

Thanks! 99p is a bargain - I'm going to order some even if I don't need it right now. It must cost more than 99p to post it!

walpurgis

04-04-2016, 23:02

Scrape the old gasket off and carefully remove any sticky residue with a cloth damped with thinners or white spirit. Don't let it get on anything else.

madders

06-04-2016, 18:00

I've been listening to these for the last couple of days. One speaker sounds excellent (the one I did first). I've realised there is a problem with the midrange driver in the other one. There is a fair amount of distortion at times. I've taken it out again to have a look and I guess there must be something wrong with the voice coil. It's rubbing when I push it in or out by hand. I'm not sure whether to attempt repairing it, or just look for a replacement on eBay.

walpurgis

06-04-2016, 18:27

DarrenHW

06-04-2016, 18:28

madders

06-04-2016, 20:13

I take it you are referring to the 5" mid in the 44s.

You could have a look at my recommendation here. It often works'

http://theartofsound.net/forum/showthread.php?44021-Help-Required-Re-centre-a-Kef-B110&p=742222#post742222

Yes the 5" mid - I've attached a couple of pics. I want to try your suggestion with the hair dryer but I can't figure out how to get to the voice coil. I took the three screws out the back, but I can't see how to take it apart without cutting the front.

16620 16621

Also it appears to be rubbing on every side, so maybe it's just totally knackered?

Look no further: http://theartofsound.net/forum/showthread.php?44205-Celestion-Spares-Ditton-66-44-25-HF2000-MF500-D5

PM me if you're interested.

Great thanks! I spent ages looking on eBay earlier! The ones you have for sale look exactly like what I have. If I can't fix it with the hair dryer, I'll PM you. Thanks!

karma67

06-04-2016, 20:22

has this driver always done this or has it happened after you did the recap?

walpurgis

06-04-2016, 20:34

Yes the 5" mid - I've attached a couple of pics. I want to try your suggestion with the hair dryer but I can't figure out how to get to the voice coil. I took the three screws out the back, but I can't see how to take it apart without cutting the front.

My god. What have you done? Put the screws back and do them up tight and just pray the magnet has not decentralised.

You don't need access to the coil. You just put an elastic band around the coil former which is the tube attached to the back of the cone. Access is through the chassis openings behind the cone.

The rear spider is the corrugated bit behind the cone.

madders

06-04-2016, 22:23

My god. What have you done? Put the screws back and do them up tight and just pray the magnet has not decentralised.

You don't need access to the coil. You just put an elastic band around the coil former which is the tube attached to the back of the cone. Access is through the chassis openings behind the cone.

The rear spider is the corrugated bit behind the cone.

Wow it worked! Despite removing the screws (luckily they went back in ok). And I completely misunderstood your instructions. First I pulled it up and heated it, and it wouldn't go back down. Then when I finally realised what you meant with the elastic band, I was pulling it way too tight. Eventually I realised it only needed pulling very slightly. It's still rubbing a little bit, but there is a huge improvement, and no distortion anymore. I'll have another go tomorrow and see if I can get it perfect. I'm amazed I haven't broken it completely!

madders

06-04-2016, 22:26

has this driver always done this or has it happened after you did the recap?

I think it must have been the same before the recap. Something didn't sound right, and this must have been the problem. It's very noticeable on piano music, which I didn't listen to before. But I put some on after the recap because I thought it would be good to test the crossover.

walpurgis

06-04-2016, 22:34

That's a relief. Find exactly where the coil is rubbing by pressing gently on the coil former all round and moving the cone backwards and forwards a bit until you get the worst contact noise. The elastic band needs to pull exactly in the opposite direction that you are pressing, but not too strongly. Don't overdo the heat either. Just take everything steadily and do it again if not happy. This dodge will normally work, unless the coil is damaged. Either by overheating from too much power causing the coil coating lacquer to bubble and expand or ovality due to ageing or poor manufacture (and yes, I've seen both).

DarrenHW

07-04-2016, 07:33

madders

07-04-2016, 20:51

Sounds like your getting there Michael :). Are you aware that periodically rotating the bass driver is recommended to compensate for the surrounds sagging under weight possibly causing rubbing of the voice coil?

Hi Darren - yes I've read that a few times, but I didn't look which way round they were before I took them out! I have put them back with the wires at the top, I think it's most likely they were at the bottom before.

walpurgis

07-04-2016, 21:09

I wouldn't worry too much. Suspension sag seems to affect larger drivers most. Usually low resonance types with soft, pliant surrounds.

madders

07-04-2016, 21:34

Thanks Geoff. And thanks again for the advice. I had another go with the hair dryer earlier. Made it worse again at first, but with a bit of patience I've got it just about perfect.

The speakers are sounding really good now. I'm probably just imagining it (because I've read so much about needing to burn in capacitors), but I think there is an improvement now, compared to straight after I did them. Or maybe it's just that one of the speakers isn't distorted anymore!

I'm going to take a look at the 25s at the weekend.

walpurgis

07-04-2016, 21:50

Yes. I've made it worse occasionally. It's a method of curing binding coils I've used quite a few times. Many years ago I bought a batch of old Decca bass drivers. Half of them had rubbing cones and I fixed them with a hairdryer. It's a method I devised myself at that time (seemed pretty obvious to me).

andyrlb

06-05-2016, 06:09

Hi Madders,
Hope you don't mind me asking how you got on doing the refurbishment on your 44's ? I am in need of little advice about mine , basically I have no feed to the tweeters .
Regards
Andy

madders

06-05-2016, 14:10

Hi Andy,

I've been listening to my 25s the last few weeks, trying to decide if it's worth recapping them or not.

I finished the 44s and they sound very good.

I'm not sure how much I can help you - I don't really know that much. If you've got the same problem with both tweeters, it seems more likely the issue is with your amp. The wiring inside the speakers is really simple, so it's easy to check the connections between the terminals and the tweeter. You can also test the resistance across the tweeter with a multimeter to see if it's faulty - I think it should be 8ohms.

Virtual-Symmetry

06-05-2016, 22:56

DarrenHW

07-05-2016, 06:09

And at are my favourite cap without a doubt

I now know why and you've never been shy about recommending them for Celestions http://theartofsound.net/forum/showthread.php?11212-Celestion-Ditton-44&p=214304#post214304. A pity I took the long way round, ~£60 per re-cap, 2-4 hours to do the work and 100+ hours of burn in equals a lot of wasted time! Andr'e may appear to be a noob but there aren't many members here with his knowledge of vintage HiFi, listen to the Reformed One :youtheman::youtheman::youtheman: