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Old 6th September 2007, 03:40 PM   #121
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Hi ReLLaXX, and welcome to our thread !

I think I've understood all your words -"wnglish" for english seems more a finger slip, which I do too often with some other words.

Anything you want to post to tell us about, or photos to look at, will be most welcome.

There will be more information from me about getting the cross-overs working to close to original specification as soon as I have sufficient time available, and there will likely be more from the three 66 owners after they've had time to try the ideas posted to date.
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Old 6th September 2007, 04:35 PM   #122
sba is offline sba
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Hi everyone /
Welcome Rellaxx


Alan--

24uf capacitor:

"check very closely the solder joints to all those 24uF and piggy-backed smaller caps, and compare the solder joints' colour , etc ... to the original solder joints around all the other components to see if its possible some were re-soldered later.".........

"another possible reason for the larger series capacitance to the MD500 in the 50watt version is that perhaps that version of the driver had a different Fs to the later 80watt version, and thus a slightly different Impedance around the 500Hz area, and/or a slightly different Frequency Response at the low end of its useable spectrum."


On all four crossovers, I couldn't discern any color differences in the solder joints. Moreover, the electrical tape that binds the capacitors seems to be original, uniform, and undisturbed. My overall impression is that the crossovers have not been altered or repaired.

Since one woodie crossover (with its 80watt midrange and 28uf cap) has a capacitor that is very close in value to the earlier blackies (with their 50watt midranges and 30uf caps), I wonder if Celestion was simply making adjustments at this crossover location as a response to damaged drivers that might have been showing up in their repair shop--before they ended up at the final 24uf value with the later woodies.

"check both vintages of woofers to see if any evidence on their labels, or stampings on their chassis or back of their cones, or simple visible differences in the front of their cones, of differences between the vintages."

When I purchased the blackies (advertised as being in excellent working condition) both arrived with damaged woofers. I ended up getting replacement woofers on ebay--a single woofer from a ditton 44, and two woofers (from either 44's or 66's) from another purchase. (Alan, you assisted me with this problem last summer).
Also, the dust caps on these replacement woofers are larger than on the originals; thus, they sit further towards the front of the cone, and reduce its apparent depth.
So, anyway, blackie's woofers are all mixed up now.

*************************

replacement caps:

...how you are going to fit the new caps on your old boards, because the Polypropylene caps, and anything else as good, are all larger size dimensions than those old Black electrolytics.

See post #115

***************************

erie & arco treble capacitors:

Eries---these are probably Paper-in-oil, and may still be OK if there is not evidence of substances leaking from within - look around where the leads connect to the body.

Arco---"as they are each 2.2uF, X2 = 4.4uF , instead of Celestion's 4uF, check their solder joints to see if original, or if evidence of later soldering - they could have been installed by a modifier or repairperson."


I didn't notice any leaks....all look original.

***************************

I hope to be getting some test equipment to measure the capacitance value and ESR (at 100 kHz, I think) on all the caps....Iíll let you know.


sba
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Old 8th September 2007, 03:54 PM   #123
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Default old Paper-in-Oil capacitors ; ESR ; Celestion 44 cross-over ?

sba , I'll post some comments inside the Quote Box below, following each --->

Quote:
Originally posted by sba


On all four crossovers, I couldn't discern any color differences in the solder joints. Moreover, the electrical tape that binds the capacitors seems to be original, uniform, and undisturbed. My overall impression is that the crossovers have not been altered or repaired.

Since one woodie crossover (with its 80watt midrange and 28uf cap) has a capacitor that is very close in value to the earlier blackies (with their 50watt midranges and 30uf caps), I wonder if Celestion was simply making adjustments at this crossover location as a response to damaged drivers that might have been showing up in their repair shop--before they ended up at the final 24uf value with the later woodies.

----> this is possible, and its safest if we do the same unless other information becomes available.
__________________________________________________ __

When I purchased the blackies (advertised as being in excellent working condition) both arrived with damaged woofers. I ended up getting replacement woofers on ebay--a single woofer from a ditton 44, and two woofers (from either 44's or 66's) from another purchase. (Alan, you assisted me with this problem last summer).

----> Hah, I now remember, and just did a Seach here and found the Thread ... well, I'm pleased the drivers all worked, and that you are continuing with your 66s - follow-up is often interesting !
__________________________________________________ __

Also, the dust caps on these replacement woofers are larger than on the originals; thus, they sit further towards the front of the cone, and reduce its apparent depth.
So, anyway, blackie's woofers are all mixed up now.

----> I presume you mean that those dust caps are different to the type on the woofers in your woodys also ?
or only than the damaged originals from your blackies ?

If they are different to the woodies type also, then we really do not know the optimum cross-over filter for their roll-off, because the different type of dust cap will produce a different frequency response shape at the upper end of the bandwidth.
Thus, I think they will all be the 44s type of woofer, as the 44 had a different midrange driver.
I don't know if the 44 used the same cross-over as the woodie era 66, or if it simply used the same circuit board but with different values of capacitance and inductance where relevant.
I think simply the same citcuit board is more likely the case.

There is some data for the 44 woofer in another Thread in this Forum, but I don't remember if any 44 cross-over data anywhere.
Perhaps tonedef2 knows something more about the 44 and its cross-over ...


Pete, are you reading this, about the 44 crossover, any comments ?

__________________________________________________ __




erie & arco treble capacitors:

[I]Eries---these are probably Paper-in-oil, and may still be OK if there is not evidence of substances leaking from within - look around where the leads connect to the body.


I didn't notice any leaks....

----> Good, you may be able to continue using them.
I have to go now but will continue on this next time, I hope ...
__________________________________________________ __

I hope to be getting some test equipment to measure the capacitance value and ESR (at 100 kHz, I think) on all the caps....Iíll let you know.

----> for measuring capacitance will be useful, but don't spend any money for an ESR measuring device if it measures only at 100 kHz.
100 kHz ESR is useful to know when one is working with Radio Frequencies, and similar, but we are working with Audio Frequencies, and the specific ESR values we need to know are those in the cross-over regions, that is around 500 Hz and around 5 kHz.
ESRs will be quite different at 500 Hz than at 5 kHz, and both will likely be very different to the values around 100 kHz, unless a co-incidence as result of manufacture of one or more of those caps.


sba

Pete,

if you're only glancing at this Post, have a look at the 44 question I wrote inside the Quote Box above.
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Old 11th September 2007, 03:51 PM   #124
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Default the crumbling capacitors, etc ...

Quote:
Originally posted by sba
**************
SOUND CHECK---

I can't do a sound check on blackie's tweeters or crossovers, because I pulled the boards to get the capacitor info, and half of the capacitors crumbled apart. So the blackies are out of commission until I rebuild the boards.

__________________________________________________ __

Also noticed--- While all the other caps seem to be non-polar (bi-polar), the large red-colored CCL 24uf 25v REV cap has colored markings on each end (black on the left, silver on the right, where the positive is connected). The black-colored end is also identified with a ridge.

Sba
What has "crumbled" is at most simply the Insulation, and may be only the coating. You can check this easily with your multimeter in its Resistance function.

Do this test fairly quickly because with the very low resistances you will find, and the likelihood of the capacitors charging up, the battery in your meter will be supplying a lot of current thus may expire sooner than you expect.

Touch one probe to the exposed metal body of one of the Erie caps, and scratch it gently to expose clean metal for good electrical contact, but not so hard as to risk piercing it .
Touch the other probe to one of that caps leads and notice what first happens, and then notice if any other occurrence begins after a few seconds, then remove that probe and touch it to the other end of the cap's lead, and notice again, as before.

Do you get an almost zero resistance at one end, and does it remain at almost zero ?

At the other end, do you get a reading that is not stable, and which very soon starts to cause the digits on the meter to change as if something is electrically charging up ?

Try this with every cap in the treble sections of both Blackie cross-overs.

Next, are the now exposed metal bodies touching each other in each group of caps ?

IF you got a stable near zero resistance reading to one end of each cap, is that near zero resistance to the same end of each cap in each bunch ?
That is, you will see where all the leads from each cap in each bunch join together on the circuit board for each end of each bunch.

Basically, if all caps in each bunch give near zero resistance stabily to the same common point, and none do to the opposite end of the bunch common point, then you can still use those caps because there will be no short circuit.
The outer metal case is thus connected to the lead at the end where you get the near zero resistance reading.

If you got no stable near zero resistance readings for any of the caps, then it indicates the outer cases are simply cases and are not part of the electrical circuit.
In such case you should have seen a stable infinitely large resistance reading, or an Open Circuit reading
{unless your fingers of both hands were touching the metal of the both probes, in which case you would have been measring the high resistance of your body, hand to hand circuit}.

One problem will be if you get a stable near resistance reading between the metal body and both ends of any capacitor.

The only other circumstance that would prevent you being able to use those caps with insulation missing is if one is connected in the reverse direction to the others in its bunch AND has its exposed metal case touching one of the other caps exposed metal case.
Then you would have a Short Circuit, and should not use, unless you disconnect and reverse the direction of the particular capacitor.
__________________________________________________ __

That CCL 24uF 25 volt REV electrolytic capacitor :-

I think REV indicates REVERSABLE , and if so the cap is basically Bipolar and can be used in an AC circuit {such as the one it is currently in} with no regard to which direction it is connected in.

If it does have + and - markings on its case, then such would likely indicate the preferred direction for it to be connected if it is used in a cuircuit where there is both AC and DC voltages present simultaneously {or each at some time during the operating cycle of the circuit}.
Such is possible for some types of electrolytic capacitor internal construction.

A Polarized cap would not work there in a loudspeaker cross-over, BUT in this case the is a small bipolar cap connected in parrallel with it, thus that bipolar would obscure the partial malfunction of any Polar electro in parrallel with it.
Celestion would not have put a Polarized cap in there, thus it is either a Reversable electro, or a polar cap that some-one else has installed after it left Celestion premises.

I think you would have noticed a very different midrange sound from one Blackie to the other if that is a polarized cap !
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Old 12th September 2007, 03:43 AM   #125
sba is offline sba
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Alan,

Better yet.....I'll get some capacitance values from those old crumbling Erie Research Technologies caps (in a week or two, when I get access to a meter). You're right, my horror at seeing all that cracked and crumbling insulation and in thinking that everything must be replaced, might turn out to be otherwise. It would be a pleasant surprise if all, or at least some of those Eries, can be re-used, since oil-impregnated metallized film caps are expensive to replace.

I've been reading more about caps, checking prices, and mulling over what sort of budget I have for all this.....four Ditton 66 crossovers plus....well, I just took a look inside my Dahlquist DQM-9's and noticed that thereís a total of eight, large-value, 25 year old electrolytic caps.

Until I measure all the caps, the following discussion is sort of premature, but my rough plan is to work on the blackie crossovers first. I'm assuming that all the large-value electrolytics will need to be replaced with metallized polypropylene (MKP). Iím pretty sure that I can make the adjustments needed to fit their larger size.

On another website, which has a group of people restoring AR speaker crossovers, the conclusion was that one of the most important things is to stick as close as possible to the original capacitance values (in doing so, minor variations in ESR become less important). So, in choosing cap replacements, I thought I should look for a 5% or better cap tolerance (but I really don't know....maybe 10% would be okay too). And since I'll also be measuring the new replacement caps to make sure I know what's going into the crossovers, I want to buy from someone who will easily accept returns if necessary. It looks like Parts Express and Parts Connexion have somewhat adequate return policies.

So, then....5% or better metallized polypropylene caps at PartsExpress or similar store: there's Axon, Jantzen (made in Poland), Solen (made in France), Bennic xpp, Dayton 1% (Bennic and Dayton made in China by same manf.) , and Audyn MKP. They all seem to be in the same price range. Clarity Cap (made in England) is more expensive.

For the two 72uf (and maybe the 24uf ) locations, I'm leaning towards Solen (using one 68uf and one 4uf). But Iím open to any suggestions.

The treble and midrange cap choices seem somewhat more complicated. I've read that dual-layer polypropylene film and foil cap construction produces the least inherent noise (noise is more evident in the standard single-layer metallized polypropylene caps, which invariably have noise-producing pinhole tears created in the film manufacturing process and/or in the cap winding process). Thus, in this regard, the film and foil caps are said to be well-suited for the treble and midrange circuits. So, if I had my druthers, I would use such film & foil caps (e.g., Audyn MKP plus 2%, Audiocap theta, Hovland Musicap), but their price is around seven to eight times greater than standard metallized polypropylene....Not really in my budget.

My hope, at the moment, is that the Erie caps from the two blackie crossover boards will turn out to be acceptable, and that I'll be able to spread them equally to the 6uf/4uf/4uf locations on all four of the crossover boards--making up the uf difference by bundling them to new metallized polypropylene, inexpensive film & foil, or inexpensive oil & paper.

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Old 12th September 2007, 10:08 PM   #126
sba is offline sba
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The meter arrived early.
Here are the capacitor readings from my four Celestion 66 crossovers:

* Crossovers are listed from oldest to newest (1-4) [1973-1977]
* ESR in ohms @ 100 kHz
* Out-of-circuit measurements made with a Peak Atlas esr60

************************************************** ***

72 uf elcap 50v--

(a) location
blackie 1.......ESR= 0.12 / uf= 82.98
blackie 2.......ESR= 0.12 / uf= 77.72 --(two 30s & one 12 bundled)
woodie 3......ESR= 0.18 / uf= 85.96
woodie 4......ESR= 0.13 / uf= 86.05

(b) location
blackie 1.......ESR= 0.12 / uf= 69.27
blackie 2.......ESR= 0.14 / uf= 64.19 --(two 30s & one 12 bundled)
woodie 3......ESR= 0.20 / uf= 84.49
woodie 4......ESR= 0.12 / uf= 77.98

************************************************** **

4 uf elcap 50v--

blackie 1.......ESR= 0.98 / uf= 3.72
blackie 2.......ESR= 1.22 / uf= 3.60
woodie 3......ESR= 2.80 / uf= 4.00
woodie 4......ESR= 0.89 / uf= 3.88

************************************************** **

24 uf ccL 25v--

blackie 1.......ESR= 0.08 / uf= 25.94
blackie 2.......ESR= 0.10 / uf= 17.20
woodie 3......ESR= 0.10 / uf= 22.97
woodie 4......ESR= 0.09 / uf= 26.06 --(elcap 50v)

+ piggyback 6 uf elcap 50v on
blackie 1.......ESR= 0.65 / uf= 6.02
blackie 2.......ESR= 0.66 / uf= 5.91

+ piggyback 4 uf elcap 50v on
woodie 3.......ESR= 1.46 / uf= 3.99

= Summary at this location:
30uf blackie 1.......uf= 31.96
30uf blackie 2.......uf= 23.11
28uf woodie 3......uf= 26.96
24uf woodie 4......uf= 26.06

************************************************** **

6 uf bundled treble cap location--

blackie 1.......ESR= 0.11 / uf= 3.95 --(three 2.0 Erie 150v)
...................ESR= 0.07 / uf= 2.94
...................ESR= 0.08 / uf= 2.21
blackie 2.......ESR= 0.08 / uf= 2.40 --(four 1.5 Erie 150v)
...................ESR= 0.09 / uf= 3.94
...................ESR= 0.09 / uf= 3.01
...................ESR= 0.10 / uf= 4.07
woodie 3......ESR= 0.06 / uf= 5.96 --(four 1.5 M312 erie 250v)
woodie 4......ESR= 0.06 / uf= 6.22 --(four 1.5 M312 erie 250v)

= Summary at this 6uf location:
blackie 1.......uf= 9.10
blackie 2.......uf= 13.42
woodie 3......uf= 5.96
woodie 4......uf= 6.22


************************************************** **

4 uf bundled treble cap location--

blackie 1.......ESR= 0.08 / uf= 4.54 --(two 2.0 Erie 150v)
...................ESR= 0.10 / uf= 4.26
blackie 2.......ESR= 0.12 / uf= 2.20 --( two 2.2 Arco 100v)
...................ESR= 0.21 / uf= 2.14
woodie 3......ESR= 0.06 / uf= 3.81 -(two 1.5 / one 1.0 M312 erie 250v)
woodie 4......ESR= 0.05 / uf= 4.09 -(two 1.5 / one 1.0 M312 erie 250v)

= Summary at this 4 uf location:
blackie 1.......uf= 8.80
blackie 2.......uf= 4.34
woodie 3......uf= 3.81
woodie 4......uf= 4.09


************************************************** **
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Old 13th September 2007, 03:53 PM   #127
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Default old Capacitors and types of Leakage

Its good your Meter arrived, and some interesting results, but some of those should be interpreted with caution.

First, as you wrote :-

"Out of circuit measurements"

Do I understand correctly, did you disconnect every capacitor , and the in-bunch measured M312 Eries, from the circuit completely at at least one end ?

Any component connected in parallel with a capacitor will affect the meter reading, even the hand to hand finger flesh of your body.
I have heard of some types of Meters which can perform measurements with the circuit remaining connected, but I do not know of such for capacitance meters, nor can I think how such could be possible.

The 72 uF elcaps :- I am not surprized, even the largest measurement is only just under + 20%, and + or - 20 % is common for elcaps, and some have wider Tolerances.

BUT, before we consider most of the caps :-

Leakage affects measurements !

Leakage :- in the past few posts where I have suggested inspecting the cap bodies for signs of leakage, I was refering to physical leaks of substances,
{and it seems there are none from your caps, sba
other readers, check your caps visibly in the manner I explained in a previous Post}.

Now we have to take into account Electrical Leakage ,
that is leakage of Charge.
Basically if an electrically leaky cap is charged up to any Voltage and then disconnected from the circuit {quickly so that the circuit does not discharge it} it will discharge through itself.

All capacitors have some electrical leakage, but for some types it is miniscule, and thus not problem, and for other types, with small leakage, it is a problem in some types of circuits and not in other types of circuits.

Paper-in Oil caps do have noticeable electrical leakage.
Well manufactured ones do not have too much, but the leakage does increase if the cap becomes hot, and such does occur when it is pasing a lot of AC signal at frequencies where it has significant Impedance.

Leakage usually increases as caps age for types that have liquids or semi-liquids such as pastes inside.
This does not normally occur with caps that have only solids inside, unless they are damaged in some way whilst in or not in use.
Thus I doubt any of the plastic film type caps in these cross-overs will be leaking charge, but such can if a manufacturing fault or later damage {I have some such}.

The Electros and the presumed Paper-in-Oils will all leak most on first charge period after disuse, such as when you have measured them, particually those you have not been using such as the Blackies !
The degree of leakage I do not know.

My experience has been that an elecrtically leaking capacitor measures larger than it is when not leaking, and the degree larger seems to be related to the degree of leakage - larger produces larger.

More on this next time, plus some suggestions !
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Old 13th September 2007, 11:51 PM   #128
sba is offline sba
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Do I understand correctly, did you disconnect every capacitor , and the in-bunch measured M312 Eries, from the circuit completely at at least one end ?

I borrowed the meter from a friend of a friend. I was told that it's primarily an in-circuit ESR meter, but will also test for capacitance values (also in-circuit, according to the accompanying manual). ( I think the meter discharges the caps first.) But, after testing two caps in-circuit, I noticed that while the ESR part was working okay , the cap value readings were running amok into the hundreds of ufs.

So...I snipped a cap, pulled it out, attached the alligator clips (isolated, out-of-circuit, no hands touching), and pressed the test button. The results were good. It became a cap "demolition" project, where each cap was snipped and measured. After I had finished, I calibrated the meter and measured all the caps again. The results were almost identical.

I measured all the bundled caps together and then individually. The sum of the individuals equaled the bundled total; however, I thought it unnecessary to list individually those few bundled 72uf electros and Erie m312 polyesters.

On the other hand, the bundled Erie A304 and A316 were listed individually because, if they are in fact oil-impregnated metallized film caps (and somewhat stable), I would like to re-use them---one at each 4uf and 6uf treble location on all four crossovers (piggybacking something else to the Eries where necessary).

By any chance, do you know what that "A" stands for on the Erie caps? With the Erie M312's, I'm pretty sure that the "M" stands for Polyester.

*****************

I just made an impulse purchase of Solen caps!! I was going over my calculations again and realized that I had only budgeted for four 72ufs, instead of the required eight. After more price checking, I found Solen caps on sale for half the normal price at the Solen Canada web site. The catch is...it's existing stock of non environmentally friendly caps (non RoHs) which, I guess, will not be sold in the EU and elsewhere soon.

http://www.solen.ca/

click ďOn SaleĒ

When the new caps arrive, I'll borrow the meter again. For the 72uf locations, I ordered 68ufs, which I'll measure--and add ufs to, as necessary. The 24uf location can also be tweaked.

I feel better now that these large uf value caps are out of the way...they're a big expense in this restoration. For the smaller 4uf/4uf/6uf locations, I ordered a variety of uf values that can be combined, with or without the Eries, for various +/- 4 and 6 uf values. Thus, we should be able to tweak the uf values at the midrange and treble locations to exactly how we want them, while considering the DCR of the drivers.........look at poor blackie 2, with its high 5.0 DCR tweeter and ultrahigh 13.42 uf cap in the 6uf treble location.


Sba
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Old 14th September 2007, 04:38 AM   #129
ReLLaXX is offline ReLLaXX  Romania
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Hello again!

Very busy period, still I am reading everything and hope to be able to post some more soon. I made some photos, maybe this weekend I will be able to upload them. So far all the caps on my crossovers look very good, but then again, you never know. I am really missing the gear I need to do all the measurements you guys do, so for the moment I will try to read and extract the useful info.

And one more thing, I am now shure I need two midranges. Mine sound very good, nothing bad comes out, even at higher input (50-60W). But they look like the glue is al over the place and I am shure that this is not the way they suposed to be. Once you will see the pics everything will make sense.

So if anybody sees two very good midrange speakers, including on Ebay, please give me a sign here. I am cheking this thread daily so I can't miss it.

One question for you 66 users. What amps do you use? What sources and how whould you describe the result? I have a Pioneer Spec 4 on it's way (tomorow should be home) and I can't wait to see how will they match togheter.

More to be said, soon.

Cheers!

PS: Hope my English is better this time. It's a long time since I have stoped learning it.
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Old 14th September 2007, 03:47 PM   #130
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Default Too soon with Solen caps !

Hi sba,

well you've jumped the gun and ordered caps before I got to that, but since I'm going to Post my recommendations later for the other guys you will find out eventually, this I may as well say now :-

68uF + 4uF is not the best audible way to achieve 72uF.

I don't know how much it will matter for those 72uF caps in parallel with the woofers, but with two widely spaced cap values a double resonance is set up. This is not as smearing of details and dynamics as the Dielectric Absorption of electrolytic caps cause, but better can be achieved by parallelling equal or near-to values.
For 72uF I would parallel 39uF + 33uF.

For Series connected caps, such as the 24uF to the MD500, and the 4uF and 6uF to the HF2000, it is audibly more critical to pair carefully if one has to use parallels, because the differences in the Pulse Rise Times between the caps cause signal to in effect pass through one cap of the pair faster than through the other, and this audibly changes the timbre {tone character of an instrument or voice}.
Larger value caps have slower pulse rise times than smaller value caps, as do caps of different Dielectrics, and even if use the same type of dielectric but different internal construction, or even different Voltage rating {in some cases} pulse rise times can be different.

Yes, I remember that Post where you wrote some of what you had read about combining various types and values of caps, and I only commented on that briefly then.
Basically that can work in Power Supplies when one needs to filter out wide-band noise, but to apply optimally one has to measure the results to ensure there has not been created one or more Resonant modes which couple into the circuit.
It is not a simple subject and I didn't want to type hundreds of words to explain it all, nor will I now, but ... for people who like to experiment, anything can and will be tried, and some experimenters chance upon sounds they like, and other experimenters don't, but simply keep on buying components to try every idea some-one has posted about a path to Audio Nirvana, but without understanding what they are doing.

I'm sorry that I don't have sufficient time available to address quickly or always comprehensively every point someone raises in this Thread, but as it seemed that every-one was not in a hurry I would have got to cap selection after getting through the relevant interim matters.

I don't know what you've ordered for 24uF, but I hope it is simply a 24uF single cap, or two 12uF caps.
Similarly, for the 4uF I would use a single 4uF or a single 3.9uF {which is only -2% difference}.
Some Brands have a single 6uF cap, or a near to such as 6.2uF, or a close values way of pairing.
I will be listing some of these when I list the reasonable value lower priced brands.

Also, for audilble consistency, presuming one has available a well made cap, one should use the same Brand and type and model {including voltage if possible} in all positions in at least each Filter arm of the cross-over, and maybe in the entire cross-over.
Thus I would never advise paralleling different brands or dielectric types, but any-one is free to try that and listen - who knows, one may chance on something one likes for the music types one listens to mostly.

Similarly the physical sizes, 100 Volt size is adequate if well made, and one does not need the larger 250 volt nor 400 volt sizes in cross-overs for domestic use loudspeakers that will not accept such large voltages, such as these old Celestions.
High voltage caps are only of audible benefit when there are large voltage stresses.
More important is how well the cap is manufactured, and you have already read something about this - I will explain more when time is available when I am recommending the alternate brands.
Some caps are manufactured to be Signal caps in amplifiers where there is small signal AC and large DC voltages present simultaneously, and this does not occur in loudspeaker cross-overs.

Well, if you have ordered I suppose you can't cancel now.
What are the cap values in your Dahlquist DQM-9 ?
You may be able to use some of the Solens more effectively there.
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