LaScala Questions about Crossovers and Drivers

[Deang]

12 minutes ago, Trinity3 said:

Are the Al-3's and AK-3's the same, if I found AK-3's for sale?  Or can the AK-3 be converted easily to an AL-3?  

Basically. The problem here is that the AK series of networks physically separates the high pass and low pass sections. Everything related to the bass is in the bass bin. 

[OO1]

during the early  80's  ,for   warranty replacements   klipsch  sent out whatever they had on hand  at the Hope plant  based on Atlas shipments to Klipsch ,  it was not uncommon for a client  with defective dual phase plug K-55V drivers  to get back regular K-55V's  or vice versa 

[geoff.]

[geoff.]

Maybe I’m missing something?

 

 

 

[Bacek]

16 hours ago, Trinity3 said:

Are the Al-3's and AK-3's the same, if I found AK-3's for sale?  Or can the AK-3 be converted easily to an AL-3?  

 

From what I see here only difference are woofer capacitors but that is easy to correct so yes. Probably they will not be even included when you buy AK-3. Possibly 4mH inductor could be missing too but you will be able to substitute it somehow.

 

 

[mboxler]

9 hours ago, geoff. said:

Maybe I’m missing something?

 

 

 

 

That is really weird!  They do look like solder lugs, but it appears someone tried to remove the solder "globs" for some reason.  The + terminal has the normal red spot on the case, but the usual red mark on the solder "glob" is gone along with most of the glob 😕

[Deang]

Here it is with the AK network. I know from John Allen that it was the driver used to develop the AK network in anticipation of the EV replacement (K-55-M). I confirmed this with Jim Hunter.

 

EDIT:

 

@geoff. Any explanation without confirmation is just conjecture, and since you are not the original owner of those LSI's, we can't really say for sure what networks those speakers shipped with. What are the serial numbers of your speakers?

 

Another explanation is simply what Randy said.

 

I don’t make the recipes. I’m just the cook. ¯\_(ツ)_/¯ 

 

 

 

[Schu]

[hanksjim1]

43 minutes ago, Schu said:

 

@Schu Which one do you prefer?

[mboxler]

I thought it would be interesting to compare tweeter filters using a K77M.  I've never measured a Type A before, so I compared the Type A (RED) with the Type AA (GREEN), and the Type AL/AK (BLUE).  The A and AA cross around 4.5khz, while the AL/AK is around 6khz.  The Type AL/AK filter does seem more suited to the extended response of the dual phase plug squawkers.

 

[Deang]

You could measure a K-55-M with an AA to get a complete picture. Would be nice to settle this one.

 

Seems maybe you can do two port phase plug with the AA, but should not do AK/AL series networks with the single port phase plug driver. 

[henry4841]

Guys I think we are splitting frog hairs discussing this. IMHO all 3 cases will sound fantastic in the real world with nothing nasty coming from the speaker. On paper, sure one may look better than the others but let's not say the speaker system will sound awful with any of the mentioned crossovers. 

 

Oh you cannot do that, it will sound awful! I do not think any of us would say that with a straight face. Just being practical using common sense. 

[mboxler]

1 hour ago, Deang said:

You could measure a K-55-M with an AA to get a complete picture. Would be nice to settle this one.

 

Seems maybe you can do two port phase plug with the AA, but should not do AK/AL series networks with the single port phase plug driver. 

 

Same as above with K55M

 

[Deang]

Yeah, don’t run the Type AA with the two port phase plug drivers. 
 

Thank you Mike!

[geoff.]

@Deang, a little late to the party, work is really starting to get in the way of this forum, but I snapped a picture of the terminal cup/plate. Ya, who knows what someone else did to those La Scalas before I got them? They had an $8 Rat Shack piezo tweeter in one tophat and one K-43 ohmed out at 20 ohms. 

 

For eight years now I have been trying to figure out what is wrong with my perception because a pair of pristine AA crossovers, even after recapping with pseudo-authorized (mylar) capacitors,  has never sounded like “all that and a bag of chips” in any of the FIVE pairs of La Scalas I’ve owned over the years. Each pair had K-55-Ms…

 

I never found the midrange to be too loud, I always found the treble not as bright as I would have liked, but that is not uncommon for me. Before recapping I had to put my ear up to the K-77s to ensure they were working.

 

Now though, even with colorful puppets to explain what I was hearing, thanks @mboxler, I’m left with questions.

 

Hypothetically, not suggesting anyone modify any Klipsch product, how would a person correct for the overlap using an AA crossover with a dual phase plug driver?

 

I seem to remember a suggestion to add a .35 mH coil to the positive squawker output, a la A/4500.

 

Would another possibility be to add the same elliptical filter used in the AL series of crossovers and change the .245 mH to .125 mH? 

I really want to hear what the fuss is all about with the AA crossover. For starters, I imagine the un-smudged crossover would result in better imaging. 
 

So is what I’ve been hearing more like an “A” with better tweeter protection?

 

Another question now springs to mind… how did the widely accepted crossover points become 400 and 6000 Hz if the graph clearly shows 4500? 
 

…my whole life has been a lie, lol

 

 

 

 

 

 

 

 

 

 

[JohnA]

On 10/24/2023 at 3:03 PM, henry4841 said:

Guys I think we are splitting frog hairs discussing this. IMHO all 3 cases will sound fantastic in the real world with nothing nasty coming from the speaker. On paper, sure one may look better than the others but let's not say the speaker system will sound awful with any of the mentioned crossovers. 

 

Oh you cannot do that, it will sound awful! I do not think any of us would say that with a straight face. Just being practical using common sense. 

 

 

I had a pair of La Scalas with -M/AL networks for rear channels.  My brother has them, now.  My fronts came to me mismatched, 1981 -V/AA and 1982 -M/AL.  As luck would have it the first squawker I found was a -V and the odd one was reconfigured to 1981 spec. 

 

The -M/AL pair had a howling resonance in the lower registers of a French horn and I HATED them.  My brother or I converted them the -V/AA, neither of us can remember which.  I think the contouring in the Type AL was to blame and the AK/AB/AL was pretty quickly replaced with -2 versions.  That pair were 1985-ish vintage and had the later round magnet woofers.  The T-S are different from the square magnet woofer, I recommend AL-3s with those because the howl was near the crossover to the K-400 and the AL-3 has similarities, but is simpler than an AL.