la scala crossover question

[xaf]

Hi everyone,

 

I'm new here. My name is Xavier, I'm based in The Hague, Holland. I have a background in audio-visual art but I make most of my living as a theatre technician. I've been leeching this forum for a while now, looking for info on La Scala crossovers mainly. Problem is, the more I read, the more confused I get...

 

I have this pair of pretty beaten-up looking La Scalas in storage and I would like to get them in proper working order again. There's a bit of story to them so I'll start with that before I get to my actual question(s). These particular speakers used to belong to a school where a friend of mine works. I assume they used them as a PA system, because they look like they were. The school wanted to get rid of them, I could pick them up for free. This was sometime back in 2001. They looked like junk, dried-out gaffer tape all over, wood chipped off the sides and a terrible matte black paint job. One of the them had an extra driver attached to them, guerrilla DIY style. Each had a different crossover. At the time, I had no idea that these were legendary speakers, neither did anybody at that school obviously... Unfortunately, I never really had time to look in to them properly and when I moved abroad I gave them to another school (where I studied music). Not much later, I heard that this school's technician had had a look at them, decided they were too much hassle to fix up and moved them to some deep and dark corner of the building.

 

Years went by... Moved to yet another country, came back to Holland in 2009. Last year, I accidentally stumbled upon a second hand listing for a pair of speakers that looked strikingly a lot like those black monsters that were given to me 15 years ago. Although I never really missed them much, I did have the occasional moment of regret about getting rid of them without ever having heard them. The seller was asking 2000,- euro. Admittedly, they were in a really nice shape but I still couldn't believe it. So I asked my old school if they still had them and if I could have them back. They were happy to oblige and the Scalas were delivered to the theatre where I work when one of the schools' orchestras came to perform there. The Scalas looked even uglier then I remembered them, luckily my ears don't care much for looks. After a quick inspection of the drivers and some minor soldering to reconnect the original tweeter on the one that had the extra driver attached to it, I hooked them up to an old Pioneer amp I had lying around and it sounded surprisingly good, despite the amp being crappy, the crossovers being of two different types and capacitors undoubtedly in serious need of replacement... Obviously they sounded very different, but with both speakers placed right next to each other the total sound was promising enough in any case. However, this franken-mono setup is not something I plan to stick with ;-)

 

From what I've gathered so far, type AL is one of the original La Scala networks, which has been followed-up by AL-2 and AL-3. Then there's type A and AA, as well as the ALK universal. I'm not going to ask which one of these sounds better, I believe that that is highly subjective. Unfortunately I don't have the resources to try multiple options. Also, these speakers seems to be rather rare on this side of the Atlantic, which is likely to make things even more costly. So my first question is: are there any fellow Europeans on this forum?

 

I would like to start by bringing my Scalas back to their original state. Which means I need to find out which crossover they originally came with. One of the speakers has a type AL  the other one a type E2. The AL seems to be the obvious choice here, but considering the state they were in when given to me I'm not sure of anything anymore... The drivers in are K33, K55 and K77 (and luckily they are identical in both speakers).  The cabinets have handles on the side (I'll post some pictures when I get back to work, they're still at the theatre)

 

Next issue : budget. Even if the AL is original, I can't just start by recapping because I only have one. So far, I have had no luck finding another one (of either type). I could try to clone the AL but I'm afraid I'd have a really hard time finding the exact same inductors. Which leads me to think that maybe my best option is to build 2 entirely new crossovers myself. In which case I might as well pick another type then the AL. Which then again raises the question: so what type to start with? This has been going round and round in my head for a couple of days now, I'm kind of stuck...

 

As for amplifiers: at the moment my choices are limited to a Philips AG-7600 tube amp (stereo, with built-in spring reverb!) or a NAD 3100. I also have a Philips EL-6400, but I'd have to score another one for stereo (Fortunately, those old Philips amps are quite easily found here, Holland being their country of origin). I've considered investing in a SET too, but for now I'd only be able to afford a cheap chinese one, so I feel like I might as well save some more funds first.

 

Any advice would be greatly appreciated!

 

[Honeybadger]

Welcome to the forums.

 

Because of your situation, I think it would be best to replace the crossovers with new units. The AL is probably an original however it is not a favorite, the E2 is from a Heresy.

 

My suggestion is to get a pair of ALK Universal crossovers from ALK or a replacement crossover from Bob Crites.

 

You could certainly build a new set of crossovers. There is a link here on the forums for schematics of Klipsch crossovers.

 

HB

[wvu80]

I too have been watching the crossover (XO) threads to decide what I wanted to do with my Klipshhorn (Khorns) Type AA crossovers.  The Khorns and La Scala share the same XO.

 

In sum, the Type A enjoys a reputation for a pleasant listening experience in the living room.  The AA replaced the A with the same basic sound but included extra protection for the K-77 tweeter.  This is a so-called gentle slope XO.

 

You could also go with a steep slope XO and those are considered to have good balance between the high, mid and low frequency at higher listening levels (sound pressure level, or SPL) 

 

There are other variations and more technical explanations are available by searching these forums.

+++

 

The economical choice is to build your own, and I would recommend the Type AA.  There are plenty of schematics and the parts to build it can easily be found in the Netherlands.  There is a lot of technical support available from forum members.  This would be a solid choice.

 

If you are not comfortable building your own with that there are many who have positive experience with the various models offered by Bob Crites and ALK.  Just choose the price level or listening type you want, discuss it directly with them and you can be assured of getting a proven performer.

+++

 

That was an interesting first post, thanks for sharing.  And welcome to the Klipsch forums.          

[JohnA]

That's a Cool Story! 

 

I would choose a Type AA, if you have K-55-V squawkers (grey).  Your Type E2 can be converted to a Type AA, because the T2A transformer is the same. 

 

If you have black K-55-M squawkers, go with the Type AL-2.  Perhaps you can get a pair, or the T4A transformers, from Bob Crites.  The crossovers are not that hard to build. 

 

Here is how I like to build from scratch.  The braided copper is desoldering braid I use for the ground path.  All other connectors are soldered with silver solder (more temperature resistant) even though they are also screwed together.  That's so repairs/changes will be easier. 

 

[Marvel]

These are the ones I built for my LaScalas with the K55-M mids. The design is courtesy of the previous poster. They work great, BTW. Thanks John

 

Bruce

[BusaDude]

Here's Bob Crites website... Lots of information and you can get new crossovers/parts from him as well...

 

http://www.critesspeakers.com/crossovers.html

[xaf]

Hi everyone,

 

sorry for not following up on a thread I started myself, been rather busy with other matters lately. Thanks for all the reactions. My initial thoughts were going towards converting my AL and E2 into AA's. Or maybe even just A's to start with, mainly because of part count... I was making a list of parts I could reuse, when I realised that my AL is not the same as the schematic I found of it on the schematics page of this forum. I've attached some pictures. Mine does not have the zener diodes. The transformers are labeled 2133 (3 of those) and 3465. There are two 8uF caps, three 2uF caps and the big one reads 30 MFD, not sure if that's supposed to mean "milli" or "micro"... The resistor is 5 ohm, 10 W. The two round coils have no marking. Also, some of the wiring doesn't match the colors on the label...

 

 

So I took this AL and the E2 to a nearby D.I.Y. speaker specialist. He was very friendly, had a look at the schematics, did some measurements but in the end he couldn't really wrap his head around the design... some of the values just didn't make sense to him. He told me to find more info on the drivers and then come back. Here's what I've gathered so far, any additional info on the K55-V and the K77-M would be welcome :

 

K33E

Fs = 34.46 Hz

Qms = 7.39

Vas = 301.7 liters

Cms = 0.268 mm/N

Mms = 79.47 g

Rms = 2.328 kg/s

Xmax = 8.2 mm

Xmech = 12.3 mm

P-Dia = 336.6 mm

Sd = 889.6 sq.cm

P-Vd = 0.729 liters

Qes = 0.41

Re = 3.39 ohms

Le = 0.96 mH

Z = 4 ohms

BL = 11.93 Tm

Pe = 150 watts

Qts = 0.388

no = 2.903 %

1-W SPL = 96.78 dB

2.83-V SPL = 100.5 dB

 

K55-V

"The k-55 is def a 16 ohm driver which should have a DCR of about 10.4 to 11 ohms using a multi meter"

 

K77

"My expensive meter says the K77s I have loose measure 6.5 ohms, 6.4 ohms, and 6.6 ohms. That is appropriate for the 8 ohm nominal impedence of the K77"

 

I'm starting to have serious doubts about a DIY conversion however, it seems like the only parts I'd be able to reuse are the 2.5 mH inductors from the AL. They look a bit rusty but I think they're ok. I have only one T2A, on this side of the atlantic it seems near impossible to find a second one or a replacement. Caps would have to be replaced anyway I suppose. My local speaker guy was really scratching his head about the 13 uF though... The 1N3996 zeners are almost 30 euro's a piece at Mousers, the only shop I found them so far and they don't have them in stock... 

 

I might indeed be better of asking mr. Crites for a shipping quote and start saving up for a pair of brand new crossovers...

 

greetings from Holland,

Xavier

Edited December 16, 2016 by xaf

[ricktate]

I would forget the Zeners and just build type A crossovers. Call Bob Crites....he will help you, Not that hard to build Type As your self.Soon you could make them look pretty.

 3 capacitors, 1 Inductor, 1 transformer,  Per crossover.  So 10 parts total easy to do.

[Schu]

AA's

 

 

Edited December 16, 2016 by Schu

[JohnA]

So you have Grey K-55-V squawkers (midrange)?  If you do, the Type AL is still not right. 

 

If you don't use your La Scalas for pro sound work, you won't need the zener diodes.  They do affect the sound quality of the tweeters. 

 

Were I you, I'd order two T2A replacement transformers (autoformers) from www.critesspeakers.com, buy Solen Fastcaps from France and probably Solen's air-core inductors and build a pair of fresh crossovers that match.  The Type A or AA is easy.  *IF* you will use Tube Amps with your La Scalas, you can build a set of DHA2M2s, similar to Marvel's.  I think the tweeters need more protection that you get from the Type AA and later with amps over 50 watts. 

 

Add some wood work and pain and you'll have good looking, good sounding speakers to adorn your corners! 

[Khorns and Belles]

My AA crossovers for my Khorns before and after my rebuild with Crites parts

[Islander]

Nice crossovers, but you do know that this is a zombie thread, right?  It's had no comments from 2016, so it's not likely that you'll get any answers on it.

 

Even so, welcome to the Forum!  You'll find lots to chat about here, and about many topics.  It's a great place to learn and socialize.