modifying and recapping ditton 44's

[karma67]

Got stuck into these today,ive replaced all internal wiring,new posts and replaced all the caps,all in all its been well worth it.
add this to the Nakamichi ca5 i bought and its 2 steps forward,im just wondering when the 3 steps backwards will happen! :)

cross over before,
http://i1267.photobucket.com/albums/jj548/jamiecreig123/20150802_191547_zps8ijajtqm.jpg

and after,
http://i1267.photobucket.com/albums/jj548/jamiecreig123/20150827_201953_zpsiel3nhel.jpg

[struth]

Nice tidy job Jamie. Sound any different?

[karma67]

thanks grant,yes there is an improvement in the top end.

[Reffc]

Well done Jamie.

[karma67]

thanks paul,it was a good project for me,whats your veiws on the so called "burn in period"?
also a point of interest is that they really used any old combination of caps to get the final value,both cross overs had differences,for example for the mid,one board had a total value of 30mfd made up of one 24mfd cap and one 6mfd cap,the other board had a 24mfd cap and an 8mfd cap. the specs say total of 30mfd so i stuck to that.
i might do the other pair of ditton 44's next,these will be easier as they use the newer circuit board type board.

[Reffc]

thanks paul,it was a good project for me,whats your veiws on the so called "burn in period"?
also a point of interest is that they really used any old combination of caps to get the final value,both cross overs had differences,for example for the mid,one board had a total value of 30mfd made up of one 24mfd cap and one 6mfd cap,the other board had a 24mfd cap and an 8mfd cap. the specs say total of 30mfd so i stuck to that.
i might do the other pair of ditton 44's next,these will be easier as they use the newer circuit board type board.

Hi Jamie

there are various reasons why each side might have been different. Some manufacturers (KEF for example) matched crossovers to drivers to meet a reference response curve. Left and right crossovers may have been slightly different for that reason plus making up larger values from smaller ones is actually a good way of tightening up overall tolerances (eg 30uF at 10% could be 27uF or 33uF whereas you are more likely to get it closer to 30uF using a mix of lower value 10% caps). However, Ditton 44's were not made to individual references AFAIK, so it could simply be that they used whatever they had in the factory to get them close. That was very common for many manufacturers in the 60's, 70's and 80's.

RE settling in (I don't use burn-in terminology as its inaccurate), at the voltages concerned, it usually takes 250V polys for example a few hours to fully stabilise, sometimes more, sometimes less. I've certainly found no measurable difference in any cap for crossovers after say 10 or 12 hours. Resistors resist, that's it! Inductors are just pieces of wire with no dielectric of any consequence to stabilise so are what they are although some cored inductors, depending on rating, will exhibit some degree of hysteresis.

It's not crossover matching that matters really, its the effect of the filter transfer function on the acoustic response. The aim is for equal acoustic response. With modern drivers though which are usually a 1% or less match from the factory, it is true that most modern x-overs are equally matched.

[karma67]

another jiffy bag of caps arrived today so i set about changing the caps on the later dittons 44's with the pcb crossover.
i decided not to change the mid and hf caps as these are not electrolytic's,the other reason is that on the earlier 44 i changed the lot and although i was happy with the sound the bass seemed to be slightly down,i think this was the new polys for the mid and hf,i may be wrong of coarse.

any way the cap change was a doddle unlike the older hard wired board! first impressions are the bass is back in line with the mid and hf,the speakers sound in balance if you know what i mean and very smooth!

http://i1267.photobucket.com/albums/jj548/jamiecreig123/20150912_153742_zpskjx2mart.jpg

i plan to do the internal wiring and posts later.

[karma67]

Been busy again today,ive sold the early pair of 44's ,they sounded lovely with all caps changed and re wire so it was time to do the later pair with the pcb crossover.
whislt i was at it i thought id try them with fresh caps to the hf and mid,the rest had already been done previously.

After reading through the ditton 66 thread i wanted to try kens electrolytic/pp mix for the mids,the stock cap was 24uf,ken recommended a mix of 23uf electrolytic and 1uf pp for a bit of sparkle to the mid,this was done along with fresh ansar super sounds for the hf.

http://i1267.photobucket.com/albums/jj548/jamiecreig123/20151031_094038_zpsbeslthlm.jpg

I also wanted to get rid of the celestion block connector and solder the wires directly to the board.

http://i1267.photobucket.com/albums/jj548/jamiecreig123/20151031_132714_zpsd6qoqmgv.jpg

mounted back in the cabinet with new speaker posts fitted and all wiring replaced. a noticeable improvement and well worth doing!!

http://i1267.photobucket.com/albums/jj548/jamiecreig123/20151031_133923_zpsx4lzv23z.jpg

[walpurgis]

Well as you've got a few quid in your pocket now Jamie. Just grab these:

http://theartofsound.net/forum/showthread.php?41257-FS-Tannoy-Super-Gold-Monitor-SGM-12X

You'll never look back!

(you know we'll convert you one day :D )

[karma67]

lol you never know! although any spare cash is going in the holiday fund at the moment :)

[walpurgis]

lol you never know! although any spare cash is going in the holiday fund at the moment :)

Holidays before Hi-Fi? Your priorities are just so wrong! :lol:

[struth]

What's a holiday??;)

[karma67]

hmmm http://wonderful-places.net/wp-content/uploads/2014/09/White-beach-Boracay-Visayas.jpg
its a tough decision!

[walpurgis]

Hmm. If it's got flies, open drains, beggars and blokes with high pitched voices who wave their hands about, I ain't going there.



(It'll remind me too much of here :eek:)

[DarrenHW]

Nice one J, what do you think of the difference in the Mid compared to the Alcaps?

Been busy myself:

http://i1324.photobucket.com/albums/u606/drtwas/IMG_5728_zps9fbugpue.jpg (http://s1324.photobucket.com/user/drtwas/media/IMG_5728_zps9fbugpue.jpg.html)

significant improvement to be had by externalising IMHO.

[karma67]

we should rename this thread DITTON PORN! lol or at least ditton 44 modifications,so people have an easy reference,unless its only us that does this? lol.
Those inductors look very nice,where did you get the done?
Re the mid caps its had to say as getting rid of the standard bell wire has really made the bass come alive so i guess its had the same effect else where,i would defo try it through and see what you think,it will be a lot easier now your x-overs are on the outside to experiment.
Im liking the sound very much now,so much in fact its stopped me trawling ebay for speakers :)

[DarrenHW]

we should rename this thread DITTON PRON! lol or at least ditton 44 modifications,so people have an easy reference,unless its only us that does this? lol.

I don't know whether there is still a following for modding 44's, but I think your chosen title is appropriate:). As was pointed out to me at the weekend I can't really call my speakers 44's anymore as only the bass driver and crossover section is original, Triggers Broom MKII!


Those inductors look very nice,where did you get the done?

The inductors are Jantzen from Europe Audio, I've had to change them as the MD500 and SEAS 19TFF1 require different values to the stock 44 inductors.



Re the mid caps its had to say as getting rid of the standard bell wire has really made the bass come alive so i guess its had the same effect else where,i would defo try it through and see what you think,it will be a lot easier now your x-overs are on the outside to experiment.

Yes, rewiring is a huge improvement, I understand how it's then difficult to assess what has made what change to SQ.


Im liking the sound very much now,so much in fact its stopped me trawling ebay for speakers :)

I'd suggest you keep an eye open for a pair of Beovox 5700, I still need to rework mine so that they have a fair innings against the 44's but in stock form they're pretty good sounding speakers and if you did prefer the 44's you can take the MD500's out, stick them in your 44's and bring them up to 66 level. I think all of the complaints I had about the 44's have been down to the D5, the MD500, is more detailed, natural, smoother and images so much better. I never did get the image I wanted from the 44's, with the MD500 installed, imagining is a different, far more cohesive matter.

I'm glad you've had positive results using Ken's x-over, I'm going to give the speakers a week or so to bed in and then try the Mundorfs, if I still prefer the Poly's after that I'll fully populating the Mid with Ansars, which as you point out is a 5 minute job now, wish I'd done this months ago :doh:.

[karma67]

I'm glad you've had positive results using Ken's x-over, I'm going to give the speakers a week or so to bed in and then try the Mundorfs, if I still prefer the Poly's after that I'll fully populating the Mid with Ansars, which as you point out is a 5 minute job now, wish I'd done this months ago :doh:.

cool,well a few days in and im still very pleased with the results,im tempted to try mundorfs in place of the alcaps else where,although the size may be an issue using the stock pcb board.
could you post some pictures of your external crossover showing the layout please,as you've had success i think this is the next step forward for me,also i was looking at the jantzen inductors and they do a few different ones with the same value using different gauge wire,is it just a case of measuring the ditton gauge and buying the same?

my last upgrade in the new year is to make new cabinets with exotic veneer,keeping them simple and just copying the original cabinets.when i get round too it if you are interested i could make you a pair too as it would be not too much more work to make another pair. i'll keep you posted on that as and when. :)

[DarrenHW]

cool,well a few days in and im still very pleased with the results,im tempted to try mundorfs in place of the alcaps else where,although the size may be an issue using the stock pcb board.

Glad you're pleased with the Mundorfs, I also considered using them in the LF but quite awkward with the values available, where did you get yours, HiFi Collective?


could you post some pictures of your external crossover showing the layout please,as you've had success i think this is the next step forward for me,

Clicking on the photo I posted above should take you to my Photobucket account, go left or right and you should see more photo's, let me know if not. I based the inductor layout on this (http://www.troelsgravesen.dk/coils.htm), the LF is still original and could do with some further work.


also i was looking at the jantzen inductors and they do a few different ones with the same value using different gauge wire,is it just a case of measuring the ditton gauge and buying the same?

You need to match the resistance to the Celestion originals, I've got 2 pairs of inductors here so if you are seriously looking to replace them I can measure these, which combined with your results should give a pretty good average to get you in the ball park. However with the exception of L2 your inductors are air core so I don't know whether they'd be any benefit in replacing these, you need to speak to someone more knowledgeable than me!



my last upgrade in the new year is to make new cabinets with exotic veneer,keeping them simple and just copying the original cabinets.when i get round too it if you are interested i could make you a pair too as it would be not too much more work to make another pair. i'll keep you posted on that as and when. :)

Thank you Jamie, that is a very kind offer :) However, I think 66 clones is where I'm going and I don't need much of an excuse to get my routers out!

[karma67]

yes i got them from HiFi Collective,
maybe i'll leave the inductors alone then,thats another thing they must have tweeked from blackies to woddies along with the woofer dust caps.

[DarrenHW]

I still think re-spacing the inductors would be worthwhile even if not replacing. How were you thinking of making 72uF from the values HiFi Collective have available?

[karma67]

to be honest i hadnt gone that far yet,so dont know if i can get the 72 value using mundorf.

[karma67]

seems using them the closest you can get to 72uf is 71.9 made from a 68uf and a 3.9 i doubt the difference would be audible .

[DarrenHW]

seems using them the closest you can get to 72uf is 71.9 made from a 68uf and a 3.9 i doubt the difference would be audible .

That's all I could come up with too, I might give them a try?

[Firebottle]

The 0.1 difference in value is moot as the tolerance of the larger cap (3%) will give a difference in value of up to 2uF.

:)

[DarrenHW]

The 0.1 difference in value is moot as the tolerance of the larger cap (3%) will give a difference in value of up to 2uF.

:)

Agreed, however by the same rational a modern single low tolerance 68uF capacitor could be closer to the specified value than the original 72uF Elcap used by Celestion. We have no idea how thorough the manufacturing process was, but judging by the variety of capacitors found in different generation Celestions I'd speculate it wasn't that rigorous and the components were far from hand picked for each pair of speakers. I'm not saying this just to be a dick, but because I'm trying to make improvements to the original construction and (to my ears anyway) have achieved this by improving component quality (e.g. internal wiring) and by following rules Celestion did not adhere to (e.g. inductor placement).

My concern is not about achieving an absolute 72.00uF but how to do it if not using a single value capacitor. The rules suggest if an absolute value cannot be used the next best option is to use equal values in parallel and I don't know what the rule is if this too is not achievable. Looking at Ken's arrangement for the Mid it would seem he is not concerned about these rules and with all the experimentation he has done with the 66 x-over maybe I'm worrying about nothing, but I do like rules!

Using a 68uF with a smaller value capacitor has it's appeal. As you said, the 68uF will undoubtedly not be 68uF so with a handful of low value and low cost capacitors 72(.something)uF could be achieved. I still like rules, with limited (and I'm flattering myself here) technical knowledge, it takes the guess work out :).

[Light Dependant Resistor]

Hi
Here is a design tip for, that you are unlikely ever to find elsewhere
think of what a capacitor is - momentarily storing charge and releasing it.

Inside a speaker crossover the capacitor is either coupling or rolling off frequency
without seeing the schematic 72uf is more than likely rolling off frequency for the
bass driver, or more precisely for the benefit of frequency shelving of other drivers.

Now instead of trying to make a 72uf cap from other values, use 2x 150uf caps in series
thereby obtaining 75uf or thereabouts given capacitor tolerances usually is 10%
here is the interesting part, the midway junction of capacitor terminals + - + - make
this a inductor of suitable power handling, and I would suggest a very small toroid
winding about 20 turns.

Let me know how it goes.

Cheers / Chris

[DarrenHW]

Inside a speaker crossover the capacitor is either coupling or rolling off frequency
without seeing the schematic 72uf is more than likely rolling off frequency for the
bass driver, or more precisely for the benefit of frequency shelving of other drivers.

Hi Chris,

I think your assumption is correct, C8 & C6 being the capacitors in question:

15644



Now instead of trying to make a 72uf cap from other values, use 2x 150uf caps in series
thereby obtaining 75uf or thereabouts given capacitor tolerances usually is 10%


Unfortunately the Mundorf E Cap Plain only seem to go up to 100uF.



here is the interesting part, the midway junction of capacitor terminals + - + - make
this a inductor of suitable power handling, and I would suggest a very small toroid
winding about 20 turns.

What's the advantage to this?

[Light Dependant Resistor]

Hi Chris,

What's the advantage to this?

So C1xC2 / C1+C2 using 150uf caps is 75uf

Really needs a scope to see change of one circuit
with an inductor and one without.

In a DC circuit one would be right in saying there is not much a inductor is doing
tucked between two capacitors, as the inductor opposes current changing
and there is in theory no current, as the capacitor blocks DC

Then again when first starting a capacitor very momentarily appears as a short

Also very few DC power supply circuits are DC as there is always some 50-60hz
AC residue from rectifiers, hence a series cap and inductor midway combination has much promise

But a capacitor in a speaker is handling a music AC signal , so frequency is involved
Inductors offer low impedance with low frequency and high impedance with high frequency
the opposite of capacitors - so combining the properties of each has merit. The inductor
coming to the rescue of the capacitor, and the capacitor assisting the inductor to a degree.

If I can find some time I will breadboard each and run through a scope with say 100hz
and see what occurs with waveforms.

Cheers / Chris

[karma67]

So C1xC2 / C1+C2 using 150uf caps is 75uf

Really needs a scope to see change of one circuit
with an inductor and one without.

In a DC circuit one would be right in saying there is not much a inductor is doing
tucked between two capacitors, as the inductor opposes current changing
and there is in theory no current, as the capacitor blocks DC

Then again when first starting a capacitor very momentarily appears as a short

Also very few DC power supply circuits are DC as there is always some 50-60hz
AC residue from rectifiers, hence a series cap and inductor midway combination has much promise

But a capacitor in a speaker is handling a music AC signal , so frequency is involved
Inductors offer low impedance with low frequency and high impedance with high frequency
the opposite of capacitors - so combining the properties of each has merit. The inductor
coming to the rescue of the capacitor, and the capacitor assisting the inductor to a degree.

If I can find some time I will breadboard each and run through a scope with say 100hz
and see what occurs with waveforms.

Cheers / Chris

well that went right over my head ! in laymans terms please for me :)

[Light Dependant Resistor]

Hi Jamie123
A loudspeaker, aside from the speaker drivers uses a crossover network
the crossover network creates 2 areas for 2 way speakers like woofer and tweeter
and 3 areas for a speaker having a woofer midrange and tweeter.

These are what is termed passive components, they when placed with the correct
values achieve ability to roll frequencies off, or block low frequencies
Typical values in a speaker are 70uf for woofers and 6uf for tweeters
The capacitor momentarily stores and releases a charge. A inductor
opposes change in current - to visualise what it does you have to think of
the speaker moving it creates via this movement what is called a back EMF
which is Electromagnetic Force. The inductor is designed to contain this EMF
generated signal, and if the inductor was not there the effect of the woofer
in particular would quickly interfere with the other speakers. A resistor
changes voltage to current and values in speakers are typically 10 ohms or less
as you do not want too much resistance as it is not energy being used to
directly reproduce sound.

Getting loudspeakers to work with passive components in cabinets can be a hit and miss affair
thankfully it is a science with much history http://www.classicspeakerpages.net/library/acoustic_research/

A good loudspeaker starts its life being designed for a enclosure size, as the enclosure and
how air interfaces with that enclosure dictates low frequency response.

Loudspeakers are very much guided by the properties of three main components
( although there are many more ) those being Capacitors Inductors and Resistors
each of these has certain virtues where loudspeakers are involved.

There are also active loudspeakers here frequency division normally done by passive
components is instead done precisely with active filters and amplifiers designed
not only for the speaker but also designed with exact frequency- usually with great result.

My suggestions invite a best of both approach, as inductors and Capacitors are opposite
in their behaviour but happen to work very well together. Compare this to a glass of cold milk
Milk being the Capacitor and the Fridge being the Inductor, the attribute of becoming cold
caused by placing the milk in the fridge - er... if the power is on.

Cheers / Chris

[karma67]

great explanation mate,thank you.

[andyrlb]

Hi Jamie , I am about to replace the tweeter caps on my 44's but I'm not sure what to go for , any advice please

[karma67]

do you mean as i brand or value/size