Type AA crossover rectangular capacitor replacement

[henry4841]

If one thinks the inductors need replacing ,well thinking that way why not replace the speaker voice coils as well because they are inductors. Wire wrapped around a paper core. Really thin wire as well. I am sure the glue holding it to the paper core is not what it was when made.  Wire wrapped in a circle is a definition of an inductor. Just replace everything old. The box is old as well and the glue joints are failing along with the nails holding it together so one needs to build a new cabinet with this kind of thinking.  

[PrestonTom]

1 hour ago, henry4841 said:

Would be close enough in my world. AA's are 1st order crossovers where values are not that critical. I noticed that CBHeart wants your old square caps. ..........

You do realize that AA crossovers are NOT 1st order (the Type A were however). Maybe this was a typo. The tweeter filter is 3rd order. I hope no one gets confused about this. However, I do agree that the filter on the tweeter may not be that critical since there is so little energy (from program material) up that high anyway. 

[Tizman]

44 minutes ago, henry4841 said:

Would be close enough in my world. AA's are 1st order crossovers where values are not that critical. I noticed that CBHeart wants your old square caps. Technicians know film caps in crossover networks, and for that matter old electronic gear, rarely just fail and hold their values pretty good. Not a hard working electronic piece in a crossover network. Unless they are leaking probably still good. That being said they are sure ugly and I would probably replace just because. I restore old equipment and just replace the electrolytics and leave the films alone unless they are known to fail such as really old tube electronics. The theory being destroying the old sound many enjoy. I really do not know any restorer of old equipment either in person or online sources that replace film caps in old equipment. I cannot see why crossover networks would be any different except from those trying to sell such. It is a crap shoot if replacing caps will be an improvement. Many claim too bright after doing so. 

I have limited measuring equipment, so I’m not certain if my “close to spec” measurements are close enough.  I am currently using a DMM, an LC meter, and a cheap LCR-T4 component tester.  My Klipschorns definitely have potential.  Their bass response is much deeper and better sorted than my La Scalas.  That said, they don’t sound right overall.  The speakers don’t image well and sound confused in the treble as compared to my La Scalas.  Something is amiss.  Old film caps that I have measured with my limited equipment have been mostly good.  If the caps are good, what is causing the problem?  The drivers seem to be in good shape, and are wired properly.  The speakers are in the corners, and the corners are two block walls. The room is partially treated with sound absorbing panels and sounds good with the La Scalas.  If not the caps, what?
 

 

[Tizman]

1 hour ago, captainbeefheart said:

 

Take a look at the third picture down of the tweeter frequency response I posted 4 posts ago, you can easily see this bump at 9kHz. I can simulate whatever you want to try so you can see what will happen. I will add an inductor into the simulation where you suggest to see what happens.

That would be great.  Thanks.

[Tizman]

8 minutes ago, PrestonTom said:

You do realize that AA crossovers are NOT 1st order (the Type A were however). Maybe this was a typo. The tweeter filter is 3rd order. I hope no one gets confused about this. However, I do agree that the filter on the tweeter may not be that critical since there is so little energy (from program material) up that high anyway. 

The entire crossover is not first order, but the crossover to the woofer is just a 2.5mH inductor.  Isn’t that by definition first order?

[PrestonTom]

You are not understanding things. 

 

The low pass on the woofer is first order (as you have identified). This was true for both the Type A and the Type AA. The difference was in the high pass on the tweeter. The Type A was 1st order and the Type AA was 3rd order. This was done (along with the front-to-back diodes) in order to protect the tweeter (limit the voltage). 

 

I think we are on the same page, but I did not want others to be confused.

[henry4841]

You are correct Tom but for the 2.5 vs 2.4 inductor it is 1st order. The first crossover A was 1st order both ways. The 3rd order for the tweeter was to protect the delicate tweeter. Still 3rd is nowhere near what they are using now. From what I have read steeper crossovers are what is used in the newer models. 

[PrestonTom]

Henry, we are on the same page (you may have missed my follow up post).

 

The thing that is interesting, given the efficiency of the driver and horn loading, is just how loud that must have been to blow tweeters using a Type A or a Type AA crossover. There must be many deaf users out there ....

 

 

[OO1]

1 minute ago, henry4841 said:

You are correct Tom but for the 2.5 vs 2.4 inductor it is 1st order. The first crossover A was 1st order both ways. The 3rd order for the tweeter was to protect the delicate tweeter. Still 3rd is nowhere near what they are using now.

the K77 was not THAT delicate , it could take quite a bit of punishment ,the failures started when the tweeters  hit 20+ years old ,  then 30 and now over 40 years old -there are tons of k77 left in operation , I have several pairs that have not failed in close to 45 years ,

[Curious_George]

2 hours ago, henry4841 said:

If one thinks the inductors need replacing ,well thinking that way why not replace the speaker voice coils as well because they are inductors. Wire wrapped around a paper core. Really thin wire as well. I am sure the glue holding it to the paper core is not what it was when made.  Wire wrapped in a circle is a definition of an inductor. Just replace everything old. The box is old as well and the glue joints are failing along with the nails holding it together so one needs to build a new cabinet with this kind of thinking.  

I like your sarcasm Henry. I too get irritated hearing asinine responses from “the experts” on here sometimes. But what are we talking about… only a few people here are worthy to build crossovers. No to mention designing them which even fewer people can do. 

[Marvel]

They got blown a lot after high powered SS amps came around.

[captainbeefheart]

13 minutes ago, Marvel said:

They got blown a lot after high powered SS amps came around.

 

Yep, high powered, high distortion at high frequencies when clipping, and unstable oscillations started blowing much more  tweeters vs tube predecessors.

[Tizman]

16 minutes ago, captainbeefheart said:

 

Yep, high powered, high distortion at high frequencies when clipping, and unstable oscillations started blowing much more  tweeters vs tube predecessors.

Well thank goodness it’s all tubes for me.  I suppose the protection diodes can be safely omitted in my case.

[Islander]

My 2 cents worth:  when I got my 1974 La Scalas, they were 32 years old, and had the same style of metal can caps, with the middle ones stacked 3 high.  I listened to them for a few months, then replaced the caps with Bob Crites’s Sonicaps, with no tests done beforehand.  I just figured that at that age they had to be past their best-performing years.

 

I had no regrets!  The speakers sounded much better with the new caps, and the crossovers looked much tidier, with the smaller and fewer caps on the board.  The speakers sounded clearer, and that’s as technical a description as I can give about the improved sound.

 

Since the old caps might be heirlooms to some collector if I ever sell the speakers, I kept them, but I never considered putting them back into the crossovers.

 

[KT88]

7 hours ago, Islander said:

My 2 cents worth:  when I got my 1974 La Scalas, they were 32 years old, and had the same style of metal can caps, with the middle ones stacked 3 high.  I listened to them for a few months, then replaced the caps with Bob Crites’s Sonicaps, with no tests done beforehand.  I just figured that at that age they had to be past their best-performing years.

 

I had no regrets!  The speakers sounded much better with the new caps, and the crossovers looked much tidier, with the smaller and fewer caps on the board.  The speakers sounded clearer, and that’s as technical a description as I can give about the improved sound.

 

Since the old caps might be heirlooms to some collector if I ever sell the speakers, I kept them, but I never considered putting them back into the crossovers.

 

Pat, I wonder how bad your original capacitors may have been when you first heard them. Your new Sonicaps, on the other hand, were functional. When you hear broken Aerovox vs new Sonicaps the Sonicaps sound better. I had Sonicaps in my AA cover and I have to say that unlike Sonicaps, polyester caps fit the horns much better. The polyesters are about the same as the old Aerovox, they were polyester types too.

In other words, and without offending you, maybe you've never heard how really good your Lascalas could sound.

 

The Sonicaps sound metallic, sometimes hurt the ear, disintegrate the interaction of all three drivers and thus destroy the good timing and the impression of a powerful impulse from one cast...e.g. a powerful chord with the left hand on a large Steinway piano always has these wonderful silvery overtones. With the sonicaps they no longer form the unity and attack with the fundamental in the bass. The polyester types, on the other hand, realize that sonic feeling. Give a handful of dollars a try.

[henry4841]

11 hours ago, RandyH said:

the K77 was not THAT delicate , it could take quite a bit of punishment ,the failures started when the tweeters  hit 20+ years old ,  then 30 and now over 40 years old -there are tons of k77 left in operation , I have several pairs that have not failed in close to 45 years ,

When I say delicate we are talking only 5 watts before failure. My kids blew my tweeters on two occasions when they were but a few years old. I do not think age has anything to do with it. That being said the ones I now have in my speakers are over 20 years old without giving a problem with just me listening with them. KIDS 

[henry4841]

9 hours ago, Marvel said:

They got blown a lot after high powered SS amps came around.

The reason so many have been replaced. Granted with reasonable listening levels they will work just fine. 

[henry4841]

9 hours ago, Tizman said:

Well thank goodness it’s all tubes for me.  I suppose the protection diodes can be safely omitted in my case.

My 86 AL crossovers came from the factory without the diodes. Go figure, from all accounts they should have had them. I am using AA crossovers now with no diodes with no problems with the K77 tweeter. 

[henry4841]

49 minutes ago, KT88 said:

Pat, I wonder how bad your original capacitors may have been when you first heard them. Your new Sonicaps, on the other hand, were functional. When you hear broken Aerovox vs new Sonicaps the Sonicaps sound better. I had Sonicaps in my AA cover and I have to say that unlike Sonicaps, polyester caps fit the horns much better. The polyesters are about the same as the old Aerovox, they were polyester types too.

In other words, and without offending you, maybe you've never heard how really good your Lascalas could sound.

 

The Sonicaps sound metallic, sometimes hurt the ear, disintegrate the interaction of all three drivers and thus destroy the good timing and the impression of a powerful impulse from one cast...e.g. a powerful chord with the left hand on a large Steinway piano always has these wonderful silvery overtones. With the sonicaps they no longer form the unity and attack with the fundamental in the bass. The polyester types, on the other hand, realize that sonic feeling. Give a handful of dollars a try.

Years ago I experimented with many different capacitors in my crossovers. Just playing around. Different brands do sound different to my ears. We all do not hear the same and we do not have the same listening room. Many buy Crites crossovers and like the sonicaps. Possible have over damped rooms where they may shine. Much the same with different coupling caps in tube amplifiers. Brands do sound different. Probably has to do with the manufacturing process and quality control since they have much the same spec's on paper. At low to mid volumes one will not hear much if any difference between brand of caps. It is when you crank them up you start to hear differences. 

 

The most important thing is IF YOU LIKE THE SOUND YOU NOW HAVE LEAVE THEM ALONE. Why try and fix what is not broken. 

[KT88]

On 11/27/2021 at 12:17 AM, Tizman said:

I have limited measuring equipment, so I’m not certain if my “close to spec” measurements are close enough.  I am currently using a DMM, an LC meter, and a cheap LCR-T4 component tester.  My Klipschorns definitely have potential.  Their bass response is much deeper and better sorted than my La Scalas.  That said, they don’t sound right overall.  The speakers don’t image well and sound confused in the treble as compared to my La Scalas.  Something is amiss.  Old film caps that I have measured with my limited equipment have been mostly good.  If the caps are good, what is causing the problem?  The drivers seem to be in good shape, and are wired properly.  The speakers are in the corners, and the corners are two block walls. The room is partially treated with sound absorbing panels and sounds good with the La Scalas.  If not the caps, what?
 

 

Perhaps the lascala is simply better than the klipschorn when it comes to connecting the mids to the bass.

I suggest the following test: Build all the parts from one of the Lascalas, squaker, xover and tweeter into one of your Khorns.

Then you can compare...

1) Khorn original against Khorn with Lascala parts. If you hear differences, there is potential here.

2) Khorn (with Lascala parts in midrange, treble and xover) against the second Lascala that you have not dismantled.

If you still hear a difference here basically in the same way you have not liked and mentioned as such before then it is 100% due to the fact that they are different bass horns. There are no other influences.

If you still don't like what the Klipschhorn reproduces in it‘s midrange and treble compared to the Lascala, then it's probably the worse connection in the 400 Hz region of the Khorn from bass to midrange (which also affects the perception of treble).

 

BTW are both, the Lascala and Khorn the first of their kind which you experience?