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Old 8th January 2013, 11:10 PM   #261
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Hi Alan,

I have spent the last few days going through the documentation of this thread to make sure I have the right information. Unfortunately, I can only see the markings of one of the high frequency caps.

Following P3 of the DITTON44T.B.C. there are the following;

C1 72uf50V
C2 72uf50V
C3 2 orange caps of unknown size and a black 6uf50V
C4 6uf50V
C5,C6,C7 are 2 identical caps of 2.2uf250V
C4,C9,C10,C11 are actually 3 identical caps I suspect are 2.2uf250V

On the assumption that they are also 2.2uf, then C5,6,and 7 are 4.4uf where others have a total of 4uf, and 6.6uf where others have 6uf.

Now my dilemma. Do I order direct replacements of what is in my 44? These are different cabinets than I have seen anywhere else, with beautiful bleached rosewood veneer. or do I order what others have been ordering?

If I understood the ESR correctly, I will want to place a 0.5ohm5W in series between the 6.6uF cap and the tweeter, a 1.5ohm5W in series between C3 and L3, and a final 2.7ohm5W in series between C4 and ground. Finally, if I replace the electrolytics in the low frequency stage C1 and C2 (which I intend to do), I should put in a 1ohm5W resister between C2 and ground?

I am assuming that I can control the bass somewhat with this resister. I am finding that I like a good but not too dominant bass. Also, what do I do about the differences? I am thinking my 44s are Mark 2 without the PCB, therefore will have higher power handling. How best to confirm this? It is confusing as my crossover seems to be a hybrid between the Mark 1 and the Mark 2. A kit? If so, a well made kit!

I do like the sound of these speakers, but I found the bass a little on the light side and the mids to highs were harsh as I cranked up the power on my sansui 9090.

I have made up a parts list, but I'll wait to post it until I hear back from you.

Cheers from snowy Canada (we have about 3 feet of snow on the ground, but not after this warm spell that is coming)
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Old 9th January 2013, 05:37 PM   #262
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Default Image referred to in my previous post

I thought it might help to include the document I was referring to above. All three pages can be found somewhere in this thread. I'm coming down with the flu and don't have the energy to search for it.
Attached Images
File Type: jpg Ditton44 p3.jpg (56.1 KB, 156 views)
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Old 10th January 2013, 06:43 PM   #263
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Default Parts list and Reference Schematic

DITTON44T.B.C with ESR Correction 3766.jpgParts List

qty part description p/n price inU$S

8 36uf 250V for C1 and C2 Axon-73691 $6.96
8 3uf 250V for for C4, C6 and C7 Clarity-74389 $10.01
2 4uf 250V for C5 Clarity-74842 $10.43
2 33uf 250V for C3 Clarity-74858 $42.06
2 0R5 5 Watt for R4 Mills-71893 $3.95
2 1R0 5 Watt for R1 Mills-64619 $3.95
2 1R5 5 Watt for R3 Mills-71894 $3.95
2 2R7 5 Watt for R2 Mills-64619 $3.95

Total cost if I order these parts right now is $272.34. That is the same as what I paid for these speakers, and yet I am willing to spend this for another 30 years of great sound. I spend much more than this for computer gear that lasts only a few years. I'm not yet sure how I will deal with the much larger sized caps in C1,C2, and C3, but I think if I reorganize the layout, I should be able to fit them all in.

Last edited by TechnoDweeb; 10th January 2013 at 06:46 PM.
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Old 11th January 2013, 11:11 PM   #264
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OK, I have decided to cut out the old caps to get the size they are. I am getting cabin fever. So, using my new schematic as a reference but using the units in my crossover;

C3 = 12uf + 12 uf + 6 uf = 30 uf
C5 = 2.2uf + 2.2uf = 4.4uf
C6 + C7 = 2.2uf + 2.2uf + 2.2uf = 6.6uf

I'm thinking I should use closest to existing as possible, which means that if I look at

ClarityCap ESA Series Film Capacitor

I should get;

C3 = (12 + 12 + 6) or (15 + 15)
C5 = (2.2 + 2.2)
C6 = 3.3
C7 = 3.3

I'm thinking that since I like the way the highs are right now, I shouldn't mess around with the values in the high frequency stage, and I like the mids as well, so I should leave them alone.

In terms of power handling ability, should I consider higher power values of caps and resisters, or will power handling be limited to the power handling capacity of the drivers? Should I consider ordering a few other values of resisters for experimenting? I'm thinking mainly in terms of the low frequency stage, but I may want to fine tune the mids and high frequency stages.

What do you think?

I will be removing the tweeter and midrange in order to try and identify what variation of the 44 I have, or is it a hybrid. I'll post pictures later.
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Old 12th January 2013, 07:57 PM   #265
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Default a variation of the T.B.C. crossover

Hi TechnoDweeb ,

from your photos it is obvious that you have the earlier 44s with the T.B.C. crossovers ,
BUT , the problem is , as LucasAdamson posted in several places in this thread ,
there were 3 different versions of this model for the input capacitor of the midrange filter ...
so which to use ?
You could go with Celestion's final decision as shown on the T.B.C. schematic , #188 on Page 19 , of 24uF ...
but perhaps by then Celestion had started using the new mid-range cone ...
and if your 44s have the original mid-cone it may be better to stay with what you found in your crossover.

I recommend you do not use 33uF , because the version with caps summing closest to that may not be yours.
The larger the cap there , the more lower midrange there will be ,
and if 33uF is too large for your mid-cones there will be some lower mids bloating - a resonant excess.
I recommend you stay with what you found - caps that sum to 30uF.

From:
Madisound Speaker Components: distributor of loudspeaker drivers and parts for speaker builders.
you can buy Mail-order Claritycap PX series , including 30uF for US$20.15 , and 6uF for US$6.20 .
This is significantly lower price than the ESA series , as also is the PX 3.9uF to use instead of 4uF to the tweeter.
PX series are good quality Audio caps - I have some.
They cause much better sound than the caps used in all modern low price , and in most modern mid-price and some high price loudspeakers.

Given how old those Celestion drivers are I do not know if you will hear any improvement with the more expensive ESA series ,
and using PX in the exact values means you do not have to Parallel connect caps ,
{which unless done very carefully can result in slightly less good sound than a single capacitor}.

If you do want to spend the ESA prices , then go to:
Sonic Craft High-End DIY Audio Parts
and to their Sonicap pages , and to their Gen1 series in 200 volt.
There is 3.9uF and 4uF ; 6uF and 6.2uF ; choose whichever has the Length and Diameter that fits more neatly on your board ,
because the small difference in capacitance is negligble in this application.
There is also exact 30uF ... and Soniccraft's prices for the Mills MRA-5 resistors is US$1 less than Parts Connexion's price.

The electrolytic caps you found in the tweeter filter in your 44s are not what Celestion ever used.
These were installed by some-one else who used nearest capacitances ,
but as those are all 10% larger , I recommend you buy 3.9uF or 4uF , and 6uF or 6.2uF , as above.

The resistors:
Lucas did a lot of experimenting , and when he used 0.5 ohm to the tweeter he also had 2.0 ohms in Series with the midrange.
The Celestion HF2000 tweeter has less output than the mid-cone , thus does not need resistive attenuation.

I recommend you start with:
no resistor in the tweeter filter ,
1.8 ohms in Series with 30uF C3, and 2.7 ohms in Series with 6uF C4 in the midrange filter ,
1.0 ohms in Series with C1 , and 1.5 ohms in Series with C2 in the woofer filter.

If midrange is then too low , then swap the 1.5 ohm and 1.8 ohm resistors to 1.5 in the mids and 1.8 in the bass at C2.
This will cause slightly greater difference in the midrange than it will in the bass.

To get the Treble right , apply Felt treatment around the tweeter before you insert any resistor.
{ I have posted more about the Felt application in the Celestion 66 midrange thread , and will be posting a bit more when I have time available }.

The Power handling you asked about will be limited by the drivers , and not by any of the resistors and caps I have recommended here.

Part , or perhaps all , the sound problems you listed when driving the 44s hard with the Sansui 9090 receiver may be owing to the deterioration of caps in the receiver ,
or , as result of its Bias current having drifted too far from the optimum amount.

Do you have a Schematic for the Sansui ?
If yes , then post it here if you can.
If you cannot post it , then look inside at all its electrolytic caps.
There will be one or two large caps in the first stage of its power supply ,
and probably also two large caps at its output - one for each channel.
These output caps will not be less than 2200uF , and more likely will be 4700uF or more.
If still the original caps there , they will need to be replaced , but do not rush into buying , but post here first ,
because to get the best from a capacitor coupled output amplifier you will have to choose the type of electrolytic very carefully.

MacIntosh did not use output capacitors , but instead used output transformers -{ in all their Solid State amps , if I have been correctly informed }-
and very good transformers , because MacIntosh knew about output transformers from their earlier Tube amps -{ for which they designed their own specialist transformers }.
This is why vintage MacIntosh solid state amps are regarded so highly above the capacitor coupled output amplifiers of that era.
{ Most modern solid state amps do not need output capacitors or output transformers }.

Yes , do post photos of the backs of the midrange drivers from your 44s ,
as that will help us identify and decide which caps to use with which versions of that driver.

I have more to say about improving the sound of the bass of the 44 , but that does not involve caps or resistors ,
so I will post that at another time , as I have to go now.
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Old 13th January 2013, 06:47 PM   #266
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Default Pictures of the Midrange and Tweeter drivers

Thanks Alan,

Your advice makes sense. I am poised to order the parts Wednesday evening at the earliest.

Here are some pictures I took last night. I apologize for the poor pictures. I really shouldn't have been doing this in the evening as the flu has still got it's grip on me.

My Sansui 9090 was recapped and calibrated shortly before I traded for it. One of the reasons I went for it, because I didn't want to face another project. Of course, that doesn't mean it was done properly, or with the best components. I'll see if I can find some schematics. For now though, I think I should leave the receiver alone. I'll look at that after I have recapped the 44s and the Kef Concerto's. I see myself slowly moving towards separates.
Attached Images
File Type: jpg Ditton 44 FC6 3767.jpg (526.0 KB, 117 views)
File Type: jpg Ditton 44 FC6 3768.jpg (341.8 KB, 112 views)
File Type: jpg Ditton 44 HF2000 3771.jpg (521.0 KB, 107 views)
File Type: jpg Ditton 44 HF2000 3772.jpg (248.3 KB, 100 views)
File Type: jpg Ditton 44 HF2000 3773.jpg (263.0 KB, 23 views)
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Old 13th January 2013, 11:00 PM   #267
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replace the caps!

"no" cap is good after XX years!

as another poster said, you can use polar caps - for a test

if you are OCD, then use polar back to back
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Old 14th January 2013, 01:19 AM   #268
benb is offline benb  United States
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If you are TRULY OCD, you can "DC bias" the caps as described in this thread, but it takes twice the caps each at twice the value, though you can use any type of capacitor: Using Batteries to Bias crossovers into Class A, how does it work?
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Old 14th January 2013, 11:11 PM   #269
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I agree KMossman. I am replacing the caps. The challenge is to do it at a reasonable price and good results. As for my Sansui 9090, it was recapped just before Christmas with adjustments made. It was done by a local electrical engineering student who is a perfectionist. I do believe he used quality components, but will need to open it up to confirm.

benb, an interesting read. I'm not sure if I want to do that right now. I was quite impressed with the results from other posters of this thread. And I really like the ditton 44s. For some reason, I like them better than the 66s I had. I actually ABed the two sets of speakers and the 44s sounded better to my ears. It may have something to do with the neutrality of the 66s over the 44s.

I am on a quest for the best sound and eye candy I can get without breaking the bank. I think my ear is also getting educated as I go, and the bar is going higher. Maybe what I should start doing is getting the vendor to bring his equipment to my place for the audition. So much depends on the room... I really love the way vintage audio amps and receivers look.
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Old 15th January 2013, 07:42 PM   #270
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Default follow-up to post #263 , and some in later posts ...

DC biasing of back-to-back series connected polar electrolytics can produce good results ,
though can be done more easily in amplifers , etc ... , where there is a voltage source to obtain the bias voltage from.
With a battery for the voltage in a passive crossover I would only use such if I mounted the crossover outside the spkr cabinet ,
so that I could regularly check the battery still had voltage ,
and only if very large capacitance was needed , such as for a woofer crossed at a very low frequency ,
because otherwise I would use polypropylene caps for capacitances they are available in , so as to have low Dielectric Absorption ...
however I would use a DC biased polar pair of electros as lower cost for an experimental design circuit when deciding what capacitance was needed.

*

Technodweeb ,
in your schematic in #263 above , move R3 to the other side of the junction of C3 and L3 ,
so that it is located in direct Series with C3 before L2 in the circuit.
R3 needs to be as if an internal part of C3.
It can be connected to either side of C3 , whichever is easier to install ,
but there must be no other components connected to the junction point of C3 and R3.

For all the resistors , leave about half inch of lead straight out from each end of their body ,
then bend the leads in such way as to support the body so that the body is in air above the board , and not touching any components.
These Mills resistors are light weight and their leads are strong enough to support them.
No warm or hot spots can develop on them when they are not touching anything ,
and they will then warm evenly over all their body when you drive to high levels.

-

As you have Kef Concerto , if you find later that the Lower midrange sounds in excess with the 30uF in the Celestion 44 ,
you can use the 30uF for the Kefs , and install 24 or 25uF in the 44s.

After you have the caps and resistors installed , listen for a while with all the critical evaluation recordings you have ,
and decide about the midrange and bass performance.
Next improvement can be done to the bass , and that will be more expensive than capacitors because that requires two new inductors for each crossover.
Lower price if you can wind them yourself , but otherwise do not buy any until we discuss here ,
because with some of the brands' types you will only get different sound , as distinct from better sound.
They will be large , as will need to be made of thick wire.
Ideally , later make a new board to install new inductors and the woofer filter caps on ,
and retain the old board only for the mids and tweeter filters.
Each board can be connected separately to the cable terminals ,
or install a second pair of terminals so you can Bi-wire back to the amplifier.

Do you still have the MacIntosh amplifier ?

-

The magnet on back of your mid-cone driver looks large enough to be the large type that LucasAdamson posted about ,
though I cannot be sure until I see the other type ...
{ where is Lucas A when we need him ? }.

Stick that lifted edge of HF2000 carefully with something that will stay adhered to metal ,
but scrape clean the metal first so no surface oxide tarnish.
If you cannot obtain a metal adhesive that sets hard , then use a Roofing Silicone of the type that sticks to metal guttering , etc ...
{ not a Bathroom Tiles silicone , as that may only hold long term to ceramic }.
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Last edited by alan-1-b; 15th January 2013 at 07:48 PM. Reason: to add a sentance
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