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Old 11th October 2009, 02:06 PM   #31
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Quote:
Originally Posted by wintermute View Post
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.
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!
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Old 11th October 2009, 05:38 PM   #32
tinitus is offline tinitus  Europe
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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

Last edited by tinitus; 11th October 2009 at 05:45 PM.
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Old 11th October 2009, 07:59 PM   #33
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Quote:
Originally Posted by tinitus View Post
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

I'm not suggesting to do major changes to your xo
I have no idea how it sounds or the general design, and wouldn't 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 doesn't 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
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.
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Old 11th October 2009, 08:51 PM   #34
tinitus is offline tinitus  Europe
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Originally Posted by LucasAdamson View Post
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.

ehh, sure, but how old are these speakers

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 did say previously that you need to be very careful when making changes as it may upset the balance, even when using excact same values

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.

Bipolars are not cheap either as especially bipolars need to be good quality
There are two kinds, "roughed" film and "smooth" film
the roughed ones have higher values at same size, the smooth ones about half and may not be available in big sizes
Some say that smooth film can be equal to film caps in quality, but expencive probably costing the same as cheap film caps, or more

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

Last edited by tinitus; 11th October 2009 at 08:55 PM.
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Old 12th October 2009, 01:50 AM   #35
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Quote:
Originally Posted by LucasAdamson View Post
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...
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.
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Old 12th October 2009, 02:50 AM   #36
tinitus is offline tinitus  Europe
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Originally Posted by wintermute View Post
standard tolerances on caps are usually +-20% which is quite a lot

Any differences in the values will tend to change the crossover frequencies.

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

Last edited by tinitus; 12th October 2009 at 02:56 AM.
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Old 12th October 2009, 02:51 PM   #37
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Default PCA Cap - dielectric ? + Fleabay's cap ?

Quote:
Originally Posted by tinitus View Post
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

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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Last edited by alan-1-b; 12th October 2009 at 02:56 PM.
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Old 12th October 2009, 03:54 PM   #38
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by alan-1-b View Post
Hi tinitus !

I certainly agree with you about the audible effects of small parallel caps !!

The PCA Cap you posted the Link to -
do you know what Dielectric is used in them ?


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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Old 14th October 2009, 09:40 AM   #39
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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.....
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Old 14th October 2009, 11:56 AM   #40
speedie is offline speedie  Australia
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Default caps what caps

I thought that you had this thing nailed
please just enjoy the music
cheers speedie
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