Noticed over the last year or so that these have been getting rather "muffled" with age. (a massive dip from 3k) Having done some research i had a look at the HF2000 tweeters, suspecting they might have given up. Turns out that they are fine and still working properly and the crossover capacitors are knackered. I took one apart and replaced the 24uF capacitor with a pair of 47uF in series (just as a trial) giving 23.5uF which seems to have greatly improved things. The original PYE cap measured just over 29uF. So i took the other speaker apart today to find that the crossover is very different.
This one sounds best out of the pair.
This one sounds worse.
I am looking into replacing all of the crossover capacitors now so that they are a matched set. Can i use a single 3uF cap for the paralleled sets of 1.5uF at the top left. Are they both pairs of 1.5uF as the labels have rubbed off the one set?
This one sounds best out of the pair.
This one sounds worse.
I am looking into replacing all of the crossover capacitors now so that they are a matched set. Can i use a single 3uF cap for the paralleled sets of 1.5uF at the top left. Are they both pairs of 1.5uF as the labels have rubbed off the one set?
I can read 1.5 and 1.5 in your picture, at least in the left pair. In that case a 3.0 is the same. Those networks look like the identical layout but just built in different periods of time. Are they a matched pair? Perhaps someone replaced the whole board somewhere along the way.
Anyhow, replacing all the caps with new units of the same nominal values won't hurt anything and may improve the balance between units a little. You can confirm values when you disassemble the bundles in the lower pic.
David
Anyhow, replacing all the caps with new units of the same nominal values won't hurt anything and may improve the balance between units a little. You can confirm values when you disassemble the bundles in the lower pic.
David
Bizarrely they are a matched pair that have been owned since new, never even been modified either.
I've had another look and the other pair of capacitors are a 1.5uF and a 2uF making up 3.5uF. Presumably it would be wiser to stick with this rather than going with a single 3.3uF.
The difference between a 3.5 and 3.3 is NOT going to be audible. A 3.3 cap with a 5% variance rating could vary from 3.454 to 3.135. If you aren't using a cap meter to check actual values then worrying about .2 uF is not worth your time.
After replacing all of the caps you might once again have the sound that you once enjoyed.
But I have a hunch that the main issue with the ditton 25 design is that it doesn't have a proper midrange driver.
The woofer is nice and smooth up to 700 hz but then gets real nasty above that and thus can't really do midrange duty. On the top end you have three tweeters, (2) hf-1300 & (1) hf-2000, that also can't do midrange duty very well. So the big drop you notice at 3k is probably partly related to this.
In the ditton range, by the way, only the 66 has a proper midrange, a dome that handles 550 to 5000 hz (and one that measures just as good as the modern ATC mid dome). The 66 (the 66 & 25 & 44 all share the same woofer) also cuts out the "nasties" from the woofer with a 4th order electrical filter at 550hz.
Good luck with your project!
But I have a hunch that the main issue with the ditton 25 design is that it doesn't have a proper midrange driver.
The woofer is nice and smooth up to 700 hz but then gets real nasty above that and thus can't really do midrange duty. On the top end you have three tweeters, (2) hf-1300 & (1) hf-2000, that also can't do midrange duty very well. So the big drop you notice at 3k is probably partly related to this.
In the ditton range, by the way, only the 66 has a proper midrange, a dome that handles 550 to 5000 hz (and one that measures just as good as the modern ATC mid dome). The 66 (the 66 & 25 & 44 all share the same woofer) also cuts out the "nasties" from the woofer with a 4th order electrical filter at 550hz.
Good luck with your project!
I've ordered a whole new set of solen MKP capacitors so that i can do the lot and have a matched pair again. Looked at getting clarity cap ESA's like i got for my home made KEF chaorales but it was a bit too expensive.
Do you know that NOBODY has bothered to post a schematic of the Celestion Ditton 25 on the entire interweb...leaving people like myself guessing. 😡
What I can tell you is that bass crossovers are very sensitive to changes of capacitor type. Celestion fourth order hardly work at all with polypropylenes, needing one or two ohm resistors to repair the phase and frequency response when non-polars are replaced with them.
The trick with 12" bass and tweeter is to cross over quite low. This Wharfedale Melton looks a bit daft until you realise that the odd wharfedale tweeter crossed over at 1.2kHz. That gets it working rather well, even if dispersion is a bit limited. Definitely a far-field monitor. I used to have these:
Post that schematic with capacitor values, and I may feel inclined to give something back and make an interesting suggestion for an upgrade. 😎
What I can tell you is that bass crossovers are very sensitive to changes of capacitor type. Celestion fourth order hardly work at all with polypropylenes, needing one or two ohm resistors to repair the phase and frequency response when non-polars are replaced with them.
The trick with 12" bass and tweeter is to cross over quite low. This Wharfedale Melton looks a bit daft until you realise that the odd wharfedale tweeter crossed over at 1.2kHz. That gets it working rather well, even if dispersion is a bit limited. Definitely a far-field monitor. I used to have these:
An externally hosted image should be here but it was not working when we last tested it.
Post that schematic with capacitor values, and I may feel inclined to give something back and make an interesting suggestion for an upgrade. 😎
I cannot give you inductor values as i haven't got an LCR meter, but everything else should be correct. I've put the inductors in their places but left the values as default. (impedance can be ignored too as i couldn't be bothered to alter it)
Nice try, Kei, but that's not making sense. These things are hard to figure out. You must have a single HF1300 on some sort of midrange crossover and two HF2000 tweeters paralleled on a high pass.
The bass and HF2000 crossovers must look a a bit like this:
Have another look. 🙂
The bass and HF2000 crossovers must look a a bit like this:
An externally hosted image should be here but it was not working when we last tested it.
Have another look. 🙂
Spotted some errors, hopefully I've got it right now. (C5 should be 2uF not 3)
Yup, that makes sense. The woofer capacitor has a little coil added (maybe 0.15mH) for a slightly faster rolloff. Very sensitive to shunt capacitor and shunt coil resistance BTW, which tames a 3dB peak at rolloff, so non-polar might work better here.
You then have a bell shaped midpass filter to the two HF1300 drivers, maybe at 2kHz. Then the regular 5kHz crossover to the HF2000 which works as a supertweeter here.
FWIW, the HF1300 drivers are more like compression drivers, and can crossover quite low. Altogether quite a tricky design, because the big loud bass is awkward to match to the tweeters.
Celestion Dittton 25:
An externally hosted image should be here but it was not working when we last tested it.
The idea I had for an upgrade was to fit a dome midrange like this:
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories
Quite a bit of work to do that, but you'd end up with a Ditton 66 in effect. 🙂
Nice as it would be, i cannot see how i'd fit it in due to the shear size of it compared to the HF1300's. You could fit it in place of the HF2000 (with some liberal chopping), but then there wouldn't be anywhere to put that. Doubt the owner of the speakers would let me take them away from standard though as he's owned them from new. (they are my dad's, mine are the goodmans in this thread)
New crossover capacitors arrived today so i've done one speaker and had a listen to compare. First thing i noticed was that the mid range is much fuller on the newly refurbished one. The LF sounds tighter and less rumbly too. HF doesn't sound greatly different, slightly smoother with the solen caps vs my panasonic FM bodge. Problem is one tweeter has its little grille and the other doesn't which probably makes them sound different. (the grille fell off around 10 years ago, I've not yet managed to find it so i can stick it back on)
They are in reasonably tidy condition, although they have been painted.
They are in reasonably tidy condition, although they have been painted.
Kei, thanks for finishing the thread. Enjoyed that one. Very educational, and USEFUL to anyone else keeping these old classic speakers running. Must have cost a few quid in capacitors! 🙂
I measured all the values of the old caps after taking them all out (measured the parallel bunches as one)
This is what they should have been followed by what they were for left then right:
NORM -- L ---- R
2uF -- 2.3uF -- 5.0uF
3uF -- 3.7uF --5.2uF
3.5uF -- 4.8uF -- 8.1uF
24uF -- 27uF -- 29uF
Cost wise, it was cheaper than i expected, just a tad over £30.
This is what they should have been followed by what they were for left then right:
NORM -- L ---- R
2uF -- 2.3uF -- 5.0uF
3uF -- 3.7uF --5.2uF
3.5uF -- 4.8uF -- 8.1uF
24uF -- 27uF -- 29uF
Cost wise, it was cheaper than i expected, just a tad over £30.
Hi there,
Apologies for resurrecting this thread from June, but where did you source the capacitors from? I'm looking to do the crossovers in my 25s soon, but have only been able to find values close (but not the same as) the ones you used.
Apologies for resurrecting this thread from June, but where did you source the capacitors from? I'm looking to do the crossovers in my 25s soon, but have only been able to find values close (but not the same as) the ones you used.
I got those solen mkp capacitors from falcon acoustics. Ironically I found the missing tweeter grille yesterday and shall be reattaching it in the new year. Anyone want to recommend a suitable adhesive?
Sorry to revive an old thread, but I wanted to chime in.
I have restored a set of Celestion Ditton 25s I received about a month ago. Upon first receiving them, I was not at all impressed with the sound. However the pair I have are the first production run, and the dates on the cabinets put them at about 38 years old, so I decided to hold off on my conclusions of their sound until I had replaced their capacitors.
Good thing I did. The sound totally revitalized and now sounds MUCH better. I am listening to them right now as I type this, I have some Steely Dan going and they sound great. I own other nice speakers such as Kef 107s, IMF RSPM Mk IVs, Kef 104/2s, and while these 25s are not quite as nice, they are not really that far off and hold their own in many ways. Great detail, lovely transparency, imaging is quite nice too and the bass is full sounding and rather impressive.
I was surprised because the lack of midrange unit would cause you to think the midrange would lack. But I think for where they lack a little in the mid, they make up for it in the treble. Overall, a very nice speaker to listen to. My plan is to eventually gut these and use the parts for a pair of Celestion Ditton 66s, but these sound so nice now with the new caps that I won't be disappointed if that doesn't happen.
By the way, I bought Alcaps from Falcon Acoustics | The Leading DIY Speaker Parts and Kit Supplier since 1972. I used (per speaker):
1x 1.5uF 50v Low Loss + 2.2uF 100v Mylar Film cap
1x 3.3uF 50v Low Loss
2x 12uF 100v
I used low loss because Celestion uses them in their other models, so I felt it appropriate to "upgrade" the caps a little bit. Alcaps are the modern equivalent to Elcaps which they also used in many of their models, so they are a suitable replacement. Some people fear that using different capacitors can change the voicing, and while I disagree to some extent, the Alcaps are inexpensive and are a good replacement for speakers like Celestions if you are concerned about that.
I have restored a set of Celestion Ditton 25s I received about a month ago. Upon first receiving them, I was not at all impressed with the sound. However the pair I have are the first production run, and the dates on the cabinets put them at about 38 years old, so I decided to hold off on my conclusions of their sound until I had replaced their capacitors.
Good thing I did. The sound totally revitalized and now sounds MUCH better. I am listening to them right now as I type this, I have some Steely Dan going and they sound great. I own other nice speakers such as Kef 107s, IMF RSPM Mk IVs, Kef 104/2s, and while these 25s are not quite as nice, they are not really that far off and hold their own in many ways. Great detail, lovely transparency, imaging is quite nice too and the bass is full sounding and rather impressive.
I was surprised because the lack of midrange unit would cause you to think the midrange would lack. But I think for where they lack a little in the mid, they make up for it in the treble. Overall, a very nice speaker to listen to. My plan is to eventually gut these and use the parts for a pair of Celestion Ditton 66s, but these sound so nice now with the new caps that I won't be disappointed if that doesn't happen.
By the way, I bought Alcaps from Falcon Acoustics | The Leading DIY Speaker Parts and Kit Supplier since 1972. I used (per speaker):
1x 1.5uF 50v Low Loss + 2.2uF 100v Mylar Film cap
1x 3.3uF 50v Low Loss
2x 12uF 100v
I used low loss because Celestion uses them in their other models, so I felt it appropriate to "upgrade" the caps a little bit. Alcaps are the modern equivalent to Elcaps which they also used in many of their models, so they are a suitable replacement. Some people fear that using different capacitors can change the voicing, and while I disagree to some extent, the Alcaps are inexpensive and are a good replacement for speakers like Celestions if you are concerned about that.
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