Yeah, it's funny, because I bypassed the speaker connections to where they connect to the board, but because they were still connected, I merely eliminated the possibility of bad soldering, not a total short, which I hadn't considered as it did seem totally impossible looking from the inside of the box, as both terminals were on an insulated plate. Doh! It does seem a bit weird for Celestion to put their speaker terminals onto an aluminium id plate with only cardboard washers to protect their tiny crappy connectors from meeting the plate.
Design - appearance and budget + Capacitors
Unfortunately after Engineers have designed working Prototypes,
those get taken to Marketing Departments where the Visual Priorities are decided, such as where to put the Company's label , etc ...
AND, the Accounting Department ALWAYS wants least possible money spent,
thus likely why the cardboard washers !
Cardboard is a good insulator, when dry and undamaged,
and it seems no-one gave much thought to the Life Expectancy of this design,
nor referred the finished selling product back to the Engineering Dept !!
Now-a-days, as result of Consumer Safety Legislation,
there are final checks done which would hopefully find the potential problem you have discovered.
It is good that you have posted this, as other Celestion 44 restorers can replace those old washers !
*****************************************************
There are some audio crossover suitable Bi-Polar electrolytics available.
They have larger surge voltage capability than standard bi-polars which are made for solid-state electronics applications primarily now,
thus are better for handling the peaks of loud audio signals.
List the all Capacitance values that are in your cross-overs,
and I'll Post the cheapest suitable replacements.
However, as it seems you don't mind extending to ClarityCap prices for the treble circuit,
such would be audibly beneficial in the midrange circuit also,
but you decide, and state what you prefer to install ... ?
Look carefully, as those Parallel connected black caps may not all be 2uF - some may be 1u5 or other values.
Don't worry if there is no EXACT available cap value for the large Series connected cap in the mids' filter.
Post what is there, and I'll recommend further.
Are you buying via Mail Order - limited to UK only ? - or can to EU ? - or can to USA/Canada ?
or only buying what you can find at a local over-the-counter retailer -{who ?}- ?
Unfortunately after Engineers have designed working Prototypes,
those get taken to Marketing Departments where the Visual Priorities are decided, such as where to put the Company's label , etc ...
AND, the Accounting Department ALWAYS wants least possible money spent,
thus likely why the cardboard washers !
Cardboard is a good insulator, when dry and undamaged,
and it seems no-one gave much thought to the Life Expectancy of this design,
nor referred the finished selling product back to the Engineering Dept !!
Now-a-days, as result of Consumer Safety Legislation,
there are final checks done which would hopefully find the potential problem you have discovered.
It is good that you have posted this, as other Celestion 44 restorers can replace those old washers !
*****************************************************
There are some audio crossover suitable Bi-Polar electrolytics available.
They have larger surge voltage capability than standard bi-polars which are made for solid-state electronics applications primarily now,
thus are better for handling the peaks of loud audio signals.
List the all Capacitance values that are in your cross-overs,
and I'll Post the cheapest suitable replacements.
However, as it seems you don't mind extending to ClarityCap prices for the treble circuit,
such would be audibly beneficial in the midrange circuit also,
but you decide, and state what you prefer to install ... ?
Look carefully, as those Parallel connected black caps may not all be 2uF - some may be 1u5 or other values.
Don't worry if there is no EXACT available cap value for the large Series connected cap in the mids' filter.
Post what is there, and I'll recommend further.
Are you buying via Mail Order - limited to UK only ? - or can to EU ? - or can to USA/Canada ?
or only buying what you can find at a local over-the-counter retailer -{who ?}- ?
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Thanks once again Alan. Well, now Lorian and I each have a pair of Ditton 44s, both with replaced speaker connectors, and now working very well.
Personally speaking, I'd like to replace the caps, because I think that the cost is justified by the potential improvement.
I know that electrolytic caps, and probably other types too, have an insidious degradation, that is hard to notice, but when replaced after 40 years, should take the speakers a leap back up to original spec.
From what I read, the mids and treble caps (C1, C5 & C6 on this photo) are much more critical for quality polypropylene caps, as they are on the + side of the drivers, filtering out the bass, whereas the others are on the return from the drivers and so can be served with electrolytics without any degradation of sound whatsoever. Is that about right? I interpreted that from this quote I read:
"When it comes to high-pass filters, the best-sounding capacitors are the high-voltage Mylar and polypropylene variety. (They're also the most expensive.) With low-pass filters, however, you can use any type of capacitor – it's the type of inductor that counts."
Personally speaking, I'd like to replace the caps, because I think that the cost is justified by the potential improvement.
I know that electrolytic caps, and probably other types too, have an insidious degradation, that is hard to notice, but when replaced after 40 years, should take the speakers a leap back up to original spec.
From what I read, the mids and treble caps (C1, C5 & C6 on this photo) are much more critical for quality polypropylene caps, as they are on the + side of the drivers, filtering out the bass, whereas the others are on the return from the drivers and so can be served with electrolytics without any degradation of sound whatsoever. Is that about right? I interpreted that from this quote I read:
"When it comes to high-pass filters, the best-sounding capacitors are the high-voltage Mylar and polypropylene variety. (They're also the most expensive.) With low-pass filters, however, you can use any type of capacitor – it's the type of inductor that counts."
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I would NEVER use any other than film caps, anywhere
Though I admit even the cheapest ones are awfully expencive when BIG
And Im not into expencive stuff either, just use what sounds good, and dont let the price influence your judgement in any way
Fore inductors, use only wire wound air core when possible
No need to use very thick wire either, unless you have problems with lack of control
NEVER use standard iron powder core
Find some good toroid core, if you need them big ones
Fore internal wire, just use ordinary cheap close to costing zero single solid core copper
And not too thick ones either
Yeah, many will agree
But a word of caution
The sound may change a lot, and maybe not even to your liking
When changing components, other adjustments may be needed too
Best I can say, dont overdo it
Im sure very many people hear miracle effects from certain components because they change the sound in a way that compensates for a flawed design, mostly crossover related
So, in many cases when a certain component is suggested as being better, it could easily be very different when used in any other design
And the point of all this? the "best" is not always the bette choise
But dont let that scare you
Though I admit even the cheapest ones are awfully expencive when BIG
And Im not into expencive stuff either, just use what sounds good, and dont let the price influence your judgement in any way
Fore inductors, use only wire wound air core when possible
No need to use very thick wire either, unless you have problems with lack of control
NEVER use standard iron powder core
Find some good toroid core, if you need them big ones
Fore internal wire, just use ordinary cheap close to costing zero single solid core copper
And not too thick ones either
Yeah, many will agree
But a word of caution
The sound may change a lot, and maybe not even to your liking
When changing components, other adjustments may be needed too
Best I can say, dont overdo it
Im sure very many people hear miracle effects from certain components because they change the sound in a way that compensates for a flawed design, mostly crossover related
So, in many cases when a certain component is suggested as being better, it could easily be very different when used in any other design
And the point of all this? the "best" is not always the bette choise
But dont let that scare you
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Good to hear it is sorted. nice to know I was on the right track when I said it could be a short, just targeting the wrong spot
If you want some polyprops that should do the job without breaking the bank you could look at jarcars polyproylene caps They also have a range of electros suitable for crossovers for the larger values
They only have polyprops up to 10uf, but that will do you for most of the values you would need. certainly in the mid + tweeter section where it is probably more critical. (A bit under 13 pouds for 2 X 10 and a 4.7 would get you pretty close to your 25uf one (tolerances aside).
The big electros in the low pass I'd personally just leave as electros... will start getting expensive to replace them with film caps! There are caps available in film up to values close to that big but they are VERY expensive
Tony.
If you want some polyprops that should do the job without breaking the bank you could look at jarcars polyproylene caps They also have a range of electros suitable for crossovers for the larger values
They only have polyprops up to 10uf, but that will do you for most of the values you would need. certainly in the mid + tweeter section where it is probably more critical. (A bit under 13 pouds for 2 X 10 and a 4.7 would get you pretty close to your 25uf one (tolerances aside).
The big electros in the low pass I'd personally just leave as electros... will start getting expensive to replace them with film caps! There are caps available in film up to values close to that big but they are VERY expensive
Tony.
Why? The prices are just crazy...it might cost me hundreds to re-cap my speakers like that. I'm going with polypropylene unless someone can give me a really sensible reason not to.
I'm keeping the factory installed inductors as they are. There's no way I can realistically become more knowledgeable about these things than the UK's top speaker company of the 1970's crossover designer.
Now that's advice that makes a lot of sense. I will make sure it's OFC though, as it is only slightly more expensive and makes sense (to me).
Yeah, many will agree
But a word of caution
The sound may change a lot, and maybe not even to your liking
When changing components, other adjustments may be needed too
Best I can say, dont overdo it
Im sure very many people hear miracle effects from certain components because they change the sound in a way that compensates for a flawed design, mostly crossover related
So, in many cases when a certain component is suggested as being better, it could easily be very different when used in any other design
And the point of all this? the "best" is not always the bette choise
But dont let that scare you
That's useful information to hear. I hadn't considered that. I did think that there would be an ideal solution and only benefits, and as you say, maybe that's naive. Having said that, they are 40 years old....probably not at their best, like me.
These film caps are ok, and affordable
http://frequence-shop.dk/produkter/39-pca-caps/
I know, not all what I wrote was aimed directly at you, but just a very short summary of what I would consider sensible fore a highend design
Anyway, IF you wanted to use the much better aircore inductors, a "meter" fore measureing caps and inductors is still affordable, maybe around 100GBP
A thing I couldnt do without and use a lot
OFC copper? nah, just strip ordinary wire fore house wireing. Maybe just look in a container, and its free
Just remember, just a single wire fore each driver terminal lug. DONT be tempted to twist multiple wires, and avoid very thick ones
http://frequence-shop.dk/produkter/39-pca-caps/
I know, not all what I wrote was aimed directly at you, but just a very short summary of what I would consider sensible fore a highend design
Anyway, IF you wanted to use the much better aircore inductors, a "meter" fore measureing caps and inductors is still affordable, maybe around 100GBP
A thing I couldnt do without and use a lot
OFC copper? nah, just strip ordinary wire fore house wireing. Maybe just look in a container, and its free
Just remember, just a single wire fore each driver terminal lug. DONT be tempted to twist multiple wires, and avoid very thick ones
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Thanks Tinitus, that's very helpful. I will do the house-wiring copper single strand. Just one question - 1.5mm sq (light circuit), 2.5mm sq (sockets) or 6mm sq (oven) cable?
Those Danish caps are quite cheap. I am still concerened that it is not necessary to use anything fancy for the stage after the driver, as with the bass speaker. 2x 72uf caps per speaker is still a lot of money.
I might consider air core inductors in the future, but for now, I just want to return the speakers close to their original sound.
Also, I have a question: Can these bass return caps really be 72uf? They are so small, physically! Is that a realistic value? I thought it might be more like 7.2 or even .72 considering the physical size.
Assuming that they are indeed nonpolar electrolytics then for 72uF 50V it is more than reasonable that they are that small IMO
That is the main (only?) advantage of Electrolytics over film caps, they pack a lot more capacitance into a given unit of size! Check out this datasheet for the specs on some random non-polar electros I found through RS-Components. the 100uf 50V has dimensions of 10mm X 16mm (they didn't have a 72uF)..
Tony.
Assuming that they are indeed nonpolar electrolytics then for 72uF 50V it is more than reasonable that they are that small IMO
Check out this datasheet for the specs on some random non-polar electros I found through RS-Components. the 100uf 50V has dimensions of 10mm X 16mm (they didn't have a 72uF)..
Tony.
Thanks Tony. I need to buy some components now, and some are near impossible to find in exact values. I wonder how important it is to find exact values - all help greatly appreciated with this...
Each speaker requires, in priority:
Tweeter:
4uf 150v
6uf 150v
Midrange:
33uf 50v/25v
6uf 50v return
Bass:
72uf 50v return
72uf 50v return
For the 4x 72uF bass returns I'm going to buy axial bipolar electrolytics, probably Nichicon. I can only find 47uF or 100uF. Is it likely the original 72uF was chosen for it's proximity to the desired value, or would that be quite an exact figure? What I mean is, how would a 100uF work? Could I lose some bass? Should I build up in smaller values to reach almost the exact value? The cost is negligible.
For the mids and tweeter caps, I'm going to buy the cheapest audio grade polypropylene caps I can find, as I believe all of them will be much higher spec. than the original electros. I need 4uF x2, 6uF x4 & 33uFx2
I can get 2x 4uF caps from Fleabay for £11
I can get 4x 6uF caps by mixing values for £35 (mixing 2 values adds up the cost!)
I can get 2x 33uF caps by mixing values for £30 (mixing 2 values - various sources)
That's £80 to replace caps- eek!
Hi, about your concern of the size of the PCA caps I linked to, they are very big with very thick leads, its just the same picture they show fore all sizes
Dont be too concerned about excact value, at least not if theres a close standard value
Better and cheaper to use the closest standard value, instead of using multiple smaller ones
Im not suggesting to do major changes to your xo
I have no idea how it sounds or the genral design, and wouldnt like to gamble with your money
But I doubt the use of two big 72uf caps is right
One should be smaller
But I suggest you try first with just ONE 75uf, between the inductors
If that doesnt work perfectly, I would try and ad another smaller one AFTER the last inductor
Well, if it works it could actually save you some money
Dont be too concerned about excact value, at least not if theres a close standard value
Better and cheaper to use the closest standard value, instead of using multiple smaller ones
Im not suggesting to do major changes to your xo
I have no idea how it sounds or the genral design, and wouldnt like to gamble with your money
But I doubt the use of two big 72uf caps is right
One should be smaller
But I suggest you try first with just ONE 75uf, between the inductors
If that doesnt work perfectly, I would try and ad another smaller one AFTER the last inductor
Well, if it works it could actually save you some money
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Hi Tinitus,
The speakers are definitely designed with one 72uf to earth after the first inductor, and another 72uf after the second inductor, directly before the woofer.
What reason do you offer to change the design. They must have made them that way for a reason, right? I mean, these speakers are very well thought of, and do sound quite excellent, even before the cap changes I'm planning. I am going to put in bipolar electros in for these caps, and the cost is really negligible, so unless you're telling me it's going to improve the sound, I'll keep them both as is I think.
I will g with the Danish caps you recommended, as they are the cheapest I've seen, and they have a 33uf cap, which is a perfect replacement for the midrange.
I can suggest all sorts of things, but give promisses I cannot
Someone may correct me on this one, but I think that the voltage specs on bipolars are DC, and voltage on film caps are AC, hence the much higher voltage rating on film caps
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That is going to depend
as allways!! standard tolerances on caps are usually +-20% which is quite a lot, but maybe the original designers matched to much closer tolerances (not likely if mass produced, but if individually built then it is possible). Any differences in the values will tend to change the crossover frequencies. You can parralel multiple caps to add them together to get a particular value. but again each will have a tolerance of perhaps +-20% so what you end up with still may not match exactly... whatever you do, you will likely end up with it sounding different to what it does now. Whether it is how it was as new is something that would be very difficult to determine I would think
I guess the point of the above is not to sweat over it too much... you may find that it needs tweaking for your personal taste, or maybe it won't
In the end, if you are in the ball park for the original design, short of spending hours experimenting and tweaking I think you should end up with something that sounds fine
Since you have two sets of crossovers, you can mod one and if you don't like the results just go back to the original!
Tony.
All the caps I have used and measured have all been very close to specced value
I cant bare to listen to other than standard values
Messing with small paralel caps always seem to have artefacts that sounds worse than any positive effect, if any
Only place I would use multiple caps are when the value is bigger than available
With inductors its quite different
They can be pretty far off
And especially with inductors I have good result with careful adjusting to excact equal value in both channels
There can also be benefits from matching resistors
Some will rightfully say that driver specs are so far off that it wont matter
I would also expect so
Well, I coat my drivers carefully to sound the same, which could be one reason why it works fore me
I do know the theory that left and right channel needs to be individually adjusted, if demands are exstreme
From my experience this theory doesnt hold water
But again, it could be because I coat my drivers
I wouldnt loose my sleep over that
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PCA Cap - dielectric ? + Fleabay's cap ?
Hi tinitus !
I certainly agree with you about the audible effects of small parallel caps !!
{I have explained this phenomenon in the Celestion 66 midrange Thread started by Mr_White
- and its to much to write it all again here now.}
The PCA Cap you posted the Link to -
do you know what Dielectric is used in them ?
There should be a Code printed on the body of the caps.
If you have any, please can you Post everything that is printed on the body of one of them,
preferably from the largest one you have ... ?
**********************************************
Hello again Lucas,
"Fleabay" ... ?
Can you Post a Link, or some descriptive information so that I can find that 33uF cap you referred to ... ?
What is your preferred Budget for the Total of cost of all the necessary caps ... ?
Don't rush into buying anything, because you may unbalance the design
and get a sound that is not as coherent as can be got, even at low price.
I recommend you do NOT mix cap values, unless you want to experiment and hear the various sound effects that this can cause.
Read what I posted about this subject in the Celestion 66 midrange Thread.
Did you see a Seller of ClarityCaps with prices you liked ?
Where ?
Hi tinitus !
I certainly agree with you about the audible effects of small parallel caps !!
{I have explained this phenomenon in the Celestion 66 midrange Thread started by Mr_White
- and its to much to write it all again here now.}
The PCA Cap you posted the Link to -
do you know what Dielectric is used in them ?
There should be a Code printed on the body of the caps.
If you have any, please can you Post everything that is printed on the body of one of them,
preferably from the largest one you have ... ?
**********************************************
Hello again Lucas,
"Fleabay" ... ?
Can you Post a Link, or some descriptive information so that I can find that 33uF cap you referred to ... ?
What is your preferred Budget for the Total of cost of all the necessary caps ... ?
Don't rush into buying anything, because you may unbalance the design
and get a sound that is not as coherent as can be got, even at low price.
I recommend you do NOT mix cap values, unless you want to experiment and hear the various sound effects that this can cause.
Read what I posted about this subject in the Celestion 66 midrange Thread.
Did you see a Seller of ClarityCaps with prices you liked ?
Where ?
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Caps only have the sellers company name written
Relabelled, noone knows where they come from
Well, the only cap I have used is 100uf, on mids highpass
Dialectric is possible the cheapest
Ofcourse there are better caps
But I guess they are ok, and cheap
How good they are, I dont know
These NOS pios I got fore free
Unfortunately all 8uf
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Hi all, if you look on flea Bay you will see Wilmslow Audio has a on line store selling Caps......some vare the correct values....some will have to be coupled.....like the 72uf's but the lower caps are coreect for tweeter values.....
Example....1.5uf 50V x 4=6uf 200v.....1x6uf 400v= correct uF...but not sure about extra 200V on caps....L.L (Low Leakage)........mite put my 66's in the wheely bin.....
Hi all, if you look on flea Bay you will see Wilmslow Audio has a on line store selling Caps......some vare the correct values....some will have to be coupled.....like the 72uf's but the lower caps are coreect for tweeter values.....
Example....1.5uf 50V x 4=6uf 200v.....1x6uf 400v= correct uF...but not sure about extra 200V on caps....L.L (Low Leakage)........mite put my 66's in the wheely bin.....
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