UPGRADE: Celestion Ditton 66

   The 66s were on my wish list for a while. Pair I bought belonged to a HiFi shop and were used for many years as their reference speakers. Because of this, speakers had tatty enclosures and handle marks on the sides (more of their story can be found in vintage section of this website). Despite this bad visual condition, they were fully functional, and this is where my journey started.

What To Upgrade
   First and most important step for me would be re-capping. The crossovers are hardwired and made from components that were available in the 70s, which means - electrolytic capacitors (with an exception of the tweeter section). What makes it even worse, is the fact that these caps are way out of specs - some even 20% out! Good news is that you don't have to use over-the-top high end capacitors for this upgrade to give you good results. Good quality film caps that are within the specs will do the job. Changing internal wiring and upgrading speaker terminals is a nice thing to do too, but it is hard to say if it provides any improvements. It will definitely not make the things worse.

   Due to original caps being way out of spec, I have decided to replace them first. I have ready many positive feedback from people replacing original capacitors with Solen film capacitors and decided to use these too. Perhaps not the top of the range capacitors but way better than electrolytic ones, and within 5% tolerance too. All caps were placed on the felt pads to damp vibrations. QED Silver Anniversary cables were used to do connections on the crossovers and to replace old speaker wires. Gold plated speaker terminals were used to replace standard terminals. All joints were made with WBT Silver Solder.
   Initially I have only done the upgrade to one crossover, to check if I was able to hear the difference. I've plugged both speakers in the mono mode (so each was playing same signal) and switched between them. The upgrade made a lot more difference than expected. In short, speaker with upgraded crossover sounded a lot cleaner, more detailed and more engaging. I was very surprised as I did not expect the improvements to be so significant. I even swapped the crossovers between the speakers to ensure that the difference is a result of the crossover upgrade. Again, same effect - much improved sound. At this stage I rushed to the garage to upgrade the second crossover.  

   Having upgraded both crossovers and all wiring meant that I was able to look at the enclosures. Heavily batted chipboard did not look too promising, but, I was not in position to build new enclosures at the time, so I have decided to refurbish/upgrade the ones I had. The veneer was badly damaged in many places and some of the corners were chipped. Mixture of sanding powder and cellulose gel was used to fill in the gaps and rebuilt corners. Old varnish was sanded off. Due to imperfections in veneer, two coats of wood dye were used, topped with multiple layers of dyed varnish. The original foam strips on the front panel were replaced with 1mm felt strips, which will not deteriorate over time. Four spikes were installed at the bottom of each speaker to provide better isolation. All metal fixtures used on the outside to hold speaker drivers in place, were cleaned and painted black. The original grills were not even considered as there are made of metal and not the best quality in general. I will probably build some MDF grilles in the future.  

   Due to necessity of using multiple layers of dyed varnish, my colour choice backfired a little. Let just say that only people with acquired taste will be able to appreciate colour of these speakers ;). Despite this, they look much neater than batted enclosures and, although wood patterns are no longer visible, there is nice wood texture coming through the varnish. I will eventually build some new enclosures, from thick MDF with a lot of internal bracings, but at the moment, due to limited time, these refurbished enclosures will have to do the job.

List of Components & Prices
   Table below shows list of the parts together with prices, necessary to do the upgrade described above.

Project Summary:
Total Time: 26h
Total Cost: 185.72


Capacitors: Original Value Replacement Value Quantity Price Per Unit Total Price

Solen 400V

72uF 70uF
4 15.89
4uF 4uF 2 2.34 4.68
30uF   8.40 16.80
4uF 2 2.34 4.68
6uF 2 2.78 5.56




Miscellaneous: Item Specific Unit Quantity Price Per Unit Total Price
QED Silver Anniversary Silver Plated OFC 1m 3 7.00 21.00
Speaker Binding Posts Gold Plated Piece 4 2.50 10.00
Speaker Spikes M8 Pack 1 8.45 8.45
Anti Squeak Tape 4000x25x1mm 1m 4 1.75 7.00
Cellulose Wood Filler 175ml Can 1 5.95 5.95
Liberon Dye (Teak) 500ml Can 1 8.47 8.47
Liberon Varnish (Matt) 500ml Can 1 14.19 14.19
Spray Paint (Black) 500ml Can 1 7.98 7.98




Copyright 2014 by Brast.