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Type AA crossover rectangular capacitor replacement


Tizman
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Hi All.  I picked up a pair of Klipschorns!  They are bass cabs from the 50s with K-33-E in them, k-400 horns with K-55-V drivers and square magnet K-77 tweeters.  They sound a little off as compared to my La Scalas and sound flat with fuzzy imaging.  I was about to switch out the capacitors, but measured the ones that could be measured in circuit, and they measured reasonably well.  I haven’t seen these caps before in a Klipsch crossover so I was hoping on getting your opinions on switching them and the need for it.  Please have a look at the attached photos.

859536B5-C0F1-4D2D-913A-2663C011D5F5.jpeg

5B60F39E-94B3-4ADF-8C67-A1FE2D9B24B1.jpeg

0C394870-3781-4537-91FC-0260D8A496BC.jpeg

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I would replace all and the round inductor also. Crites or JEM can hook you up. I dont think those tested good at all. Those are from the 70s my 1972 Ks had same ones. I changed mine to the Type A with the 45oo hz mod but you have to use different tweeter if you do that. Other wise just make a type A crossover. The woofer inductor could be changd to a better one also. ERSE - Super Q (erseaudio.com)

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Very Nice!!

 

There are a few ways I go about this.

 

First I would hook up a signal generator to the input of the crossovers and then sweep each output (tweeter, mid, woofer) on an frequency analyzer to see how the filters are functioning. This will give you a great idea of which parts of the crossover are off if the frequency and roll-off are off from spec.

 

You can also disassemble all the parts and test individually, the inductors and transformers are probably fine, they can just be checked with an ohmeter to make sure nothing has failed open. The caps, I sometimes start out by throwing some DC at them and measure leakage current. Then test ESR at all frequencies or at the very least frequencies of interest, if too high they will need to be replaced.

 

The first method is by far the fastest way to see how healthy they are. That way there say the woofer and mid are functioning to spec with correct crossover frequency but the tweeter is off you only have to pull the tweeter caps and test them most likely replacing with fresh ones to bring the tweeter filter back to spec.

 

And of course there is the camp of "replace all the caps they are old" which is true they are old, but I like to spend a little extra time to exactly figure out what is off and try and keep things as original as possible. The Aerovox caps if functioning and healthy will give the appropriate sound the speaker was intended to have. If they are junk replace with  quality polyester film capacitors.

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I would replace those caps. Many good options for those. As far as inductors, they do not go bad, or should I say 99.9% still good, in a crossover network and should preform fine. One can always find better but with minimal advantage. Be sure the screw for the round inductor is brass and not steel. Test to see with magnet. 

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  Short of having test equipment to measure things with, which would be probably 95% of speaker owners, there are some general things you can figure on. I never measure capacitance and ESR on old crossovers anymore and especially on ones that old. The reason for that is that I used to do that until I concluded there were so few worth saving it was not worth it. And if say perhaps 90% of the caps measured bad why try to save one that was OK when the rejection rate indicated they would soon be bad too. Capacitance may be OK but the ESR on those will be right through the roof. I have recapped probably over 200 sets of Klipsch vintage speakers now and all show at least some improvement to dramatic improvement to my ear. I have never measured a whole crossovers output and only measure individual capacitors as they are the only components that drift over time. Jem as mentioned or Crites both have capacitors. I order from Parts Express and find that Audyn's work and are reasonably priced and do the work myself. Yes I am solidly in the replace camp.

 

  Don't throw away those old capacitors. They have some collector value and you can sell them as is on EBay and recoup some recap cost.

 

  Check the coil screw and make sure they did not stick a steel one in there. Brass or Stainless Steel only or you change the coil value from the specified one. Loosen and re-tighten all barrier strip screws and while you are in there anyway check your drives crimp connectors for tight fit. Check screws holding drivers on to be snug.

 

  Something else I have started doing is to use two caps in place of one. For the 13uf for instance perhaps a 5uf and an 8uf or any other combination that adds up to the right value gives me measurably lower ESR than a straight single 13uf cap would and those 13uf caps are not common or cheap when you find them. I do the same thing with the 2uf caps even though they are easy to find for the same reason.

 

  The idea of healthy caps that old is something I have never found data on. There is no information on allowable ESR for instance nor is there any info on allowable tolerance variation before a part should be rejected according to non existent tolerance specs on those old crossovers. For that reason I try to stay very close to the specs as listed on schematics and figure that is the ideal goal the designer had in mind for correct sound. 50 year old caps may give a sound some like but it is for sure not the sound the speaker started out with. I have yet to see anyone take new caps out and stick 50 years old caps back in because they sound better.

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54 minutes ago, Dave A said:

  Short of having test equipment to measure things with, which would be probably 95% of speaker owners, there are some general things you can figure on. I never measure capacitance and ESR on old crossovers anymore and especially on ones that old. The reason for that is that I used to do that until I concluded there were so few worth saving it was not worth it. And if say perhaps 90% of the caps measured bad why try to save one that was OK when the rejection rate indicated they would soon be bad too. Capacitance may be OK but the ESR on those will be right through the roof. I have recapped probably over 200 sets of Klipsch vintage speakers now and all show at least some improvement to dramatic improvement to my ear. I have never measured a whole crossovers output and only measure individual capacitors as they are the only components that drift over time. Jem as mentioned or Crites both have capacitors. I order from Parts Express and find that Audyn's work and are reasonably priced and do the work myself. Yes I am solidly in the replace camp.

 

  Don't throw away those old capacitors. They have some collector value and you can sell them as is on EBay and recoup some recap cost.

 

  Check the coil screw and make sure they did not stick a steel one in there. Brass or Stainless Steel only or you change the coil value from the specified one. Loosen and re-tighten all barrier strip screws and while you are in there anyway check your drives crimp connectors for tight fit. Check screws holding drivers on to be snug.

 

  Something else I have started doing is to use two caps in place of one. For the 13uf for instance perhaps a 5uf and an 8uf or any other combination that adds up to the right value gives me measurably lower ESR than a straight single 13uf cap would and those 13uf caps are not common or cheap when you find them. I do the same thing with the 2uf caps even though they are easy to find for the same reason.

 

  The idea of healthy caps that old is something I have never found data on. There is no information on allowable ESR for instance nor is there any info on allowable tolerance variation before a part should be rejected according to non existent tolerance specs on those old crossovers. For that reason I try to stay very close to the specs as listed on schematics and figure that is the ideal goal the designer had in mind for correct sound. 50 year old caps may give a sound some like but it is for sure not the sound the speaker started out with. I have yet to see anyone take new caps out and stick 50 years old caps back in because they sound better.

 

If you test with one of those hand held ESR cap testers they only test at one frequency and it's almost always at power supply ripple frequencies like 100-120Hz, you will be fooled by the readings thinking they are bad because and ESR of 7 at 120Hz means nothing in this application where you want to pass high frequencies. You want to test ESR for the 13uF at 500Hz and up, the 2uF test at 5kHz and up. You can easily see how ESR effects things with an equivalent model, I have shown on here before. For example even if the ESR is 1 for the 2uF caps it will only have a loss of 1% of signal, usually you are -6db at 5kHz from input of xo to tweeter taps, 1 ohm extra puts the signal from 63% to 62%.

 

I can post all this stuff again. The thing is the 2uF are easy to find but the 13uF isn't. If I have 1 ohm or less ESR at 500Hz and up keep it as it will do it's job just fine. The 2uF caps same. Don't get me wrong not all of these caps will always be good, it depends how they were treated in their lifetime but they are not nearly as in bad shape as people have led on about because they only test with a crummy ESR meter that only tests at one low frequency which will tell you nothing about how it will behave inside the crossover. If this is how you test crossovers then you have no business repairing them. The easiest method like I said is input signal generator and test the outputs of each filter section to their respective drivers, this will easily show if the networks are functioning properly, if they are then you can move on to diagnosing the drivers. Testing the function of these which is 3 sweeps per board, takes all of about 15 minutes for both crossovers. I am sure there is a decent electronic tech in your area that can test them for you for a nominal fee. I have tested a lot of old capacitors including old Klipsch crossovers and just about all of them will have high ESR at 100Hz which is ok but as the frequency sweeps up it drops down much lower and is usually acceptable. If the are all dried up you will not see the ESR drop down, it will be high even while sweeping up in frequency and then you know they are toast.

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I use a B&K 885 set to 1000hz. I bought this one because it was the same one Bob Crites used for cap measurements. Of course he also could measure the output of the whole crossover with other equipment which I do not have. I figure I am not guessing with poor equipment at what is going on. If I want I can also measure inductance accurately and resistance also. While I may not be able to judge  the aggregate of a whole crossover at once I can assess each component and if the values are correct I make the assumption the crossover is correct or at least according to OEM schematic specs correct.

 

 In any case back to the idea of recapping there is no doubt in my mind and practical experience there is a real benefit for the OP to recqp.

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10 hours ago, Tizman said:

Hi All.  I picked up a pair of Klipschorns!  They are bass cabs from the 50s with K-33-E in them, k-400 horns with K-55-V drivers and square magnet K-77 tweeters.  They sound a little off as compared to my La Scalas and sound flat with fuzzy imaging.  I was about to switch out the capacitors, but measured the ones that could be measured in circuit, and they measured reasonably well.  I haven’t seen these caps before in a Klipsch crossover so I was hoping on getting your opinions on switching them and the need for it.  Please have a look at the attached photos.

859536B5-C0F1-4D2D-913A-2663C011D5F5.jpeg

5B60F39E-94B3-4ADF-8C67-A1FE2D9B24B1.jpeg

0C394870-3781-4537-91FC-0260D8A496BC.jpeg

I would not touch  , alter or modify this crossover , one can see the zener diodes ,so ,  this could be a very early version of the AA which was introduced in July  1971 so 50 years old , klipsch is 75 years old ,  buy a used pair of AA ,or build a new set -

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4 hours ago, Tizman said:

Hi All.  I picked up a pair of Klipschorns!  They are bass cabs from the 50s with K-33-E in them, k-400 horns with K-55-V drivers and square magnet K-77 tweeters.  They sound a little off as compared to my La Scalas and sound flat with fuzzy imaging.  I was about to switch out the capacitors, but measured the ones that could be measured in circuit, and they measured reasonably well.  I haven’t seen these caps before in a Klipsch crossover so I was hoping on getting your opinions on switching them and the need for it.  Please have a look at the attached photos.

These are not rare, nor do they have any significant historical value.  I have seen many of these crossovers with the same capacitors.  "Reasonably well" is not what you want.  Technology has advanced just a bit in the last 60 years.

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1 hour ago, jimjimbo said:

These are not rare, nor do they have any significant historical value.  I have seen many of these crossovers with the same capacitors.  "Reasonably well" is not what you want.  Technology has advanced just a bit in the last 60 years.

100% correct. I would say they are getting harder to find though as most of us immediately throw those old caps out and replace with good caps. I have sold some on EBay and have no idea why anyone would want them. I never asked I just felt fortunate someone wanted to buy those dog barkers.

 

  Regarding the idea "one can see the zener diodes ,so ,  this could be a very early version of the AA which was introduced in July  1971 " Every AA crossover had those from beginning to end so this does not indicate "early" AA crossovers. The caps sure do though.

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28 minutes ago, Deang said:

Windings on the autotransformer are probably loose on the core too. I’ve see quite a bit of that on the older ones over the years. I would just replace them. 

do you mean replace the entire crossover or just replace  the Autotransformers

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1 hour ago, Dave A said:

Regarding the idea "one can see the zener diodes ,so ,  this could be a very early version of the AA which was introduced in July  1971 " Every AA crossover had those from beginning to end so this does not indicate "early" AA crossovers.

Dave, isn't it great how posts can be edited/manipulated to fit the level of misinformation that is so prevalent here?  Yea, WOW is right.

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