Ditton 44 cabinet rebuild ideas (plus....?)

[zingyzangyzongy]

Hi folks

Unsure which section this should go in since it may cover more than one area.

Haven't been on for a while due to other obsessions (bicycles n guitars :eyebrows:) taking over from the hifi for a bit. However, I have been thinking about upgrading my Ditton 44s and because I am about to start an evening class in woodwork (always been handy but self-taught), I am thinking of rebuilding my cabinets as my project there a) for the fun of it, and b) to improve the sound.

As I mentioned in my first comments when I joined, my 44s were in a bit of a state - the usual mangled corners and edges and damaged veneer. I sorted them out with 2-part filler and some rosewood varnish and they look so much better, but now I want to take it up a notch. I'm looking at using birch ply and copying the original design - or do you have other suggestions? I have searched around the web but haven't yet found too much on rebuilding cabinets in this way. Perhaps someone can point me somewhere? If nothing else my new cabs would be stronger and more attractive to look at - I may varnish or veneer them.

I would also want to improve anything else - bracing/baffle/front edge/deadening, etc.

I would also consider upgrading some of the electronic components but tbh, although I can handle a soldering iron OK, I glaze over instantly when you experts start talking technically. I'm lost. :scratch: I'm not that enthusiastic about learning electronics but if there were some basic replacements possible (I have read about the Ansar polyprop capacitors and Alcap electrolytics but I don't really know what is going on!), I would undertake them, I hope with advice from you kind people :eyebrows:;)

I am hoping all this would be worthwhile - I'd certainly enjoy the process! Whaddayareckin?:cheers:

[walpurgis]

I'd suggest looking through the construction projects Paul (RFC) has done (see trade section).

[DarrenHW]

I plan on building new cabinets for mine and will use BB Ply, I don't know whether there would be any acoustic benefit over MDF but I hate working with MDF so will gladly pay the premium for BB Ply. I have replaced the 44 mid range driver with Ditton 66 driver, not only this is a massive improvement over the stock 44 mid range but will also make building new cabinets easier as they are sealed units and will not require the internal cylindrical enclosure that the 44 does, this would have to be compensated for with bracing but this would be far easier to execute. Although I would say that as I have a pair of MF500's for sale :eyebrows:.

Recapping and rewiring will be recommended by everyone on here who's recapped their 44's and Ken's approach is pretty much universally accepted as the way to go http://theartofsound.net/forum/showthread.php?31916-Renovation-of-Celestion-66-Studio-Monitors&highlight=ditton.

[walpurgis]

If you now have the 66 mid fitted, you may want to compare the components on the 66 crossover with the 44. If there are differences, I reckon the best move would be to go to 66 spec.

[zingyzangyzongy]

Cheers Geoff. I just had a look and there seem to be 88 pages! Any idea which pages I could look at?

[walpurgis]

Cheers Geoff. I just had a look and there seem to be 88 pages! Any idea which pages I could look at?

Not offhand matey! :) Have a browse, you'll find some good stuff there.

[zingyzangyzongy]

Hi Darren
Thanks for your help. :) What thicknesses would you use for that, and are you doing a straight copy of the 44s? I think ply is way more attractive than mdf anyway - I want to see the wood grain and ply layers.
Tempting though your 66 mids sound, I think I will stick with the stock drivers for now while I read that thread... again ;-)

[zingyzangyzongy]

Not offhand matey! :) Have a browse, you'll find some good stuff there.

OK (rolls up sleeves) Cheers!

[DarrenHW]

If you now have the 66 mid fitted, you may want to compare the components on the 66 crossover with the 44. If there are differences, I reckon the best move would be to go to 66 spec.

Your right, the inductors need to be changed to 0.35mH and 2.2mH, I used these http://loudspeakerfreaks.com/Product.asp?Product_ID=9402, http://loudspeakerfreaks.com/Product.asp?Product_ID=9481 as the closest match to original DCR. I've also replaced the HF2000 with the SEAS 19TFF which requires an alternative inductor, optimised the placement of the inductors and mounted the crossover externally, I started a thread to document this but work has got the better of me over the last 12 months.


Hi Darren
Thanks for your help. :) What thicknesses would you use for that, and are you doing a straight copy of the 44s? I think ply is way more attractive than mdf anyway - I want to see the wood grain and ply layers.
Tempting though your 66 mids sound, I think I will stick with the stock drivers for now while I read that thread... again ;-)

I'd stick with the original thickness 3/4 / 19mm, I've spoken to Ken about this and the only modification he'd make to the original 66 cabs would be to double up for the top and bottom panels i.e. 1.5" / 38mm. I'd also flush mount the baffle as it is with the 66's

[walpurgis]

The Ditton 66/25 ABRs come up for sale on eBay periodically. There's no reason why employing these in a 66 dimensioned cabinet with 44 drivers shouldn't work. You'd then have tall floorstanders with deeper bass and just need small plinths rather than the stands that the 44s require to get them to listening height.

[DarrenHW]

That was my original plan, I'm now thinking of incorporating stereo subs instead. It is still an option but the inductors in the LF would also need to be changed.

[walpurgis]

the inductors in the LF would also need to be changed.

Not to work with the ABRs they won't. ABR's are not influenced by crossover values.

[DarrenHW]

Maybe it's the cabinet volume then? I don't know, but the 44's use 2.0mH & 3.3mH, the 66 2.2mH & 3.5mH :scratch:.

[walpurgis]

Through the lower bass the crossover has no influence and the ABRs are strictly acoustically coupled to the bass drivers in any case, so 44 drivers in a 66 cabinet with 66/25 ABRs will work just fine. The 44 bass driver being the same unit as the 66/25 speakers. Subs would just be more clutter in the room and not needed. I dislike subs anyway, I've never heard them sound quite right to me.

[walpurgis]

the 44's use 2.0mH & 3.3mH, the 66 2.2mH & 3.5mH :scratch:.

The difference in values here is so small as to be insignificant. The latitude in component tolerances will be at larger percentages than that variance in any case.

[DarrenHW]

Through the lower bass the crossover has no influence and the ABRs are strictly acoustically coupled to the bass drivers in any case, so 44 drivers in a 66 cabinet with 66/25 ABRs will work just fine. The 44 bass driver being the same unit as the 66/25 speakers. Subs would just be more clutter in the room and not needed. I dislike subs anyway, I've never heard them sound quite right to me.

Horses for courses, I prefer the DL-103 to the DL-103R :D. I've heard 66's in my room and prefer 44's + a sub. For me sub(s) are needed the 66's don't get all the way down there, which as a owner of big old Tannoys I'm sure you can understand :).


The difference in values here is so small as to be insignificant. The latitude in component tolerances will be at larger percentages than that variance in any case.

I did wonder this myself, so there we go know need to change the inductors.

[walpurgis]

Unless the inductor values are known or marked on them, they'd need to be measured. I suspect they may be similar between models though, with the cap values being that similar.

Did you know that ABRs can have their bass response extended. Adding mass to the back of the diaphragm is the usual way to do this and many ABRs are equipped with mass weights as standard to tune them to particular frequencies. Experimentation is easy, just carefully BluTak big washers to the back of the diaphragm until the required results are achieved, then bond them on.

[DarrenHW]

Unless the inductor values are known or marked on them, they'd need to be measured. I suspect they may be similar between models though, with the cap values being that similar.

Celestion did release the specs and we have copies in "The Knowledge" http://theartofsound.net/forum/showthread.php?9536-Scans-A-E:

http://www.jkwynn.co.uk/Project_Images/66/66_15.pdf

http://theartofsound.net/forum/attachment.php?attachmentid=13298&d=1412318861

Ken has taken measurements from his pair of 66's:

http://theartofsound.net/forum/showthread.php?31916-Renovation-of-Celestion-66-Studio-Monitors&p=544761#post544761


Did you know that ABRs can have their bass response extended. Adding mass to the back of the diaphragm is the usual way to do this and many ABRs are equipped with mass weights as standard to tune them to particular frequencies. Experimentation is easy, just carefully BluTak big washers to the back of the diaphragm until the required results are achieved, then bond them on.

I did but rightly or wrongly I feel bass isn't as fast (i.e. start, stop) with an ABR, this is what I heard or a least though I did with 66's that made me want to investigate subs and keep the T1600 in a true sealed cabinet.

[walpurgis]

A bigger box would extend the bottom end without using an ABR. There is a limit though, if overdone the bass ends up underdamped.

[zingyzangyzongy]

Thanks for all that, chaps.

Just to steer things gently back to my original query, after reading this and other (!) audio forums around this subject, my plan has become this:

retain original enclosure volume but use double thickness of 18mm birch ply all round (stained then varnished)
flush baffle - black or possible dark veneer (also dbl 18mm)
radiused edges all round
3mm bitumen sheet for damping
extra bracing (inc. internal corners)
replace original stuffing?
replace capacitors and resistors for like values (early x-over - need advice on that if incorrect!)


Now I have written it down, it all seems very simple but it has taken me a while to sift through many threads and opinions out there. Does this all seem like I'm heading in the right direction for improvement on my old Dittons?

Advice and comments gratefully received.

Thanks.