My 1977 LaScalas finally got their original Autoformers T2A, what a surprising reveal!

[KT88]

Who is interested in the core of this post can skip directly to the second paragraph.

I have described in other threads how I have restored my 1977 LaScala to near original condition over the last two years. Every measure was an improvement. I have walked the odyssey of wrong ways and I have learned a lot also thanks to this forum. I was naive and for some reason I wanted "change" with the stupid promise of "even more good sound".  I bought the 1977 in 1999 and I should have left everything as it was. I am completely serious about that. I was stupid and immature...because in my innermost soul I knew they were as damn good as they were left original. Most of all I remember how smooth, musical non aggressive natural and just right the sound was at the beginning.

In 2006 I got the virus of change...but I have to say also triggered by this forum. First I bought air chokes for the bass and the tweeter, but that was no longer such a nice sound. Instead of just re-tooling everything, I ordered ALK Universal Xovers because so many people on the forum raved about them. When I plugged them in I was alienated. I heard the tweeter isolated out and the sound as a whole was no longer organic. This led me to put the boxes away and listened with other boxes first, actually a shame. 
Well, since 2008 I have UJ, so the old LaScala did not have it easy at first to come back again.
Since 2020, I hear the Lascala again and I had the goal to make everything as original as possible. Honestly not primarily just for the sake of reverence, but so that I could have a new starting point as a reference. But what happened: with each step back to the original, the sound got better and better. So I learned very quickly that getting closer to the original was the way to go.
I reported it here, first the polyester caps, then (very important!) the change to the absolute exact capacitance values of the caps, believe me, there is an important difference between wrong 13.6 and 2.2 uF and right 13 and 2 uF.
Then new original diaphragms for the Atlas KV55A, remagnetize the K77 Alnicos, new sealing of the bottom plate. So I had come a good bit far and I was already pretty satisfied. Of all this, perhaps the most important single measure was the change from sonicaps to the polyester types.

 

Then just recently I happened to find some threads here about the Autoformer. After all the other experiences of significant improvements, I had become very curious. Unfortunately, I no longer have all the parts of the original Klipsch AA crossover after all the changes and also apartment moves. But.....I found my original Autoformers, in the last of many boxes in the basement. On the non-original replica type AA Xover are autoformers with the designation 3654/0909 that I have installed since 2010. (this Xover had gotten the polyester caps two years ago). It was also wired like the original T2A, ground to 0, from 13uF cap to 5 and from 4 to the squaker +.

 

Today I installed my old original T2A. First, only one speaker to compare the sound briefly in mono. That was already very insightful. The 3654 makes the squaker louder and somehow more uneven. In the 1000Hz range piano keys are too much forward. The sound is coarser and more "peasant" compared to the T2A. Listening to both speakers mono does not make an exact center, that means for me that the autoformers make a slightly different phase shift. This is not necessarily a quality criterion in itself. But the interaction with the tweeter and the woofer is much more homogeneous with the T2A. I'm not a technician, but it seems that the phase shifting is better matching using the T2A. The speaker now has improved bass energy, not only because the squaker is a tad more quiet. The bass feels more full bodied in the deeper bass region. 

The imaging is much better, I hear much more complex sound structures and more reverb in the recordings. In stereo, the positive impression is even stronger. What a great stage! So many layers of sound placement. Better and more natural impulse of piano notes and e.g. snare drum.  
But it is not the impression of only better individual elements. It is the whole sound experience. For the lack of a better description, the sound lives, breathes and transmits right into the heart. E.g. with old CSN recordings I get goosebumps.
Anyone who has such a replacement Xover Type AA should really swap the Autoformer for the real T2A. I'm not kidding. It is such a dramatic yet subtle difference. Belief me. The old LaScala has been given a new lease on life.

[KT88]

BTW I was very curious and suddenly impatient, that's why I took the autoformer to the replica xover. The next step will be that with some leisure I will clean the original board of the Klipsch AA xover and rebuild it with all the parts in new shine.
Can anyone tell me which wire of the xover is closest to the original wire? Unfortunately the original wiring no longer exists. The same goes for the wiring of the drivers. What can I take there to get very close to the original?

[henry4841]

Transformers are nothing more than wire usually wrapped around an iron core. There must be a different turn ratio on the replacement than the T2. Since you are playing some why not try some different settings on the replacement just for fun. I would be curious on the results. I am using the 3654, I believe that is the number, on my AA's that I built and am curious on your findings. I built around 30 different kinds of xovers for my speakers years ago and found some I liked better than the AA's but consider the AA's plenty good enough. It is what I am using now. None sound bad but I do not have a trained ear and do not know how a good Grand piano should sound like.

 

Any good solid copper wire 18 gauge or better would be ideal in my world. 

 

Good post.  

[OO1]

what's wrong with the old wire for the crossovers or the drivers  ,a spool of  12  gauge copper  wire should do  for the crossovers , speaker wire was zip cord .

 

 if the   jacket of the old wire is not cracked , you can re-use it ,  ( old solder , be careful , it's most likely leaded solder ) 

[winglet]

While t2a and the 3654 are providing the same attenuation in your networks, I’m going to guess the inductance is very different between the two.
 

There is a good thread on the other forum with some measurements of the t2a vs the 3636.  The 3636 has nearly twice the inductance for a given attenuation vs the t2a.  This differing inductance effects the slope of the networks.  

[mboxler]

Tap 4 on a T2A is -3.35db vs -3db on the others.

[scalawag]

2 hours ago, KT88 said:

BTW I was very curious and suddenly impatient, that's why I took the autoformer to the replica xover. The next step will be that with some leisure I will clean the original board of the Klipsch AA xover and rebuild it with all the parts in new shine.
Can anyone tell me which wire of the xover is closest to the original wire? Unfortunately the original wiring no longer exists. The same goes for the wiring of the drivers. What can I take there to get very close to the original?

Here are my original '76 'Scala X-overs cleaned up and mounted on new boards.  Except for the solid wire leads of the air-core inductor, the X-overs appear to use ordinary 18ga stranded wire between the components.  Speaking of the inductor, doublecheck the hold-down screw - it should be non-magnetic (brass) and not regular metal crews as my originals were.  Good luck on your "restoration."

 

[KT88]

53 minutes ago, OO1 said:

what's wrong with the old wire for the crossovers or the drivers  ,a spool of  12  gauge copper  wire should do  for the crossovers , speaker wire was zip cord 

 

, if the   jacket of the old wire is not cracked , you can re-use it ,  un-solder the wires , remove  the old solder (  be careful , it's most likely leaded solder ) ,  tin the ends and re-solder with leaded solder  if you can still find it  .

Thanks, everything is correct with the original wires. Unfortunately, I no longer have mine since 16 years, hence my question.

[KT88]

22 minutes ago, scalawag said:

Here are my original '76 'Scala X-overs cleaned up and mounted on new boards.  Except for the solid wire leads of the air-core inductor, the X-overs appear to use ordinary 18ga stranded wire between the components.  Speaking of the inductor, doublecheck the hold-down screw - it should be non-magnetic (brass) and not regular metal crews as my originals were.  Good luck on your "restoration."

 

Thanks for the info. Now that I see your photo I remember the red dotted white cables. The question remains whether it is pure copper stranded wire, which I also assume? 

Yes, the story with the magnetic mounting screw of the air choke was known to me and I have replaced it with another screw made of non-magnetic material.
Now it is so that I no longer have the original air choke for the tweeter and also not the 2.5 mH bass coil. Are the components of the replacement crossover (BC) in any other respect than induction value different from the originals?
 

[OO1]

54 minutes ago, KT88 said:

 , hence my question.

Heinz ,  PM @Trey Cannon    

[babadono]

Well in your picture of the 2 autoformers the 3654 certainly looks like the iron core is larger.

[Deang]

Contrary to what we’ve been told over the years by various individuals, the T2A has working inductance in parallel with the K-55. It creates a 12dB/octave slope. The same applies to the other Klipsch spec autoformers, though in some cases an inductor is put in parallel with the autoformer to maintain the 12dB/octave slope below the cutoff frequency. 
 

The 3619 and all its variants (3636, 3654, 3619-ET, and 3675) have twice the inductance. They also use a different steel for the laminations. They curve different. Based on what I’ve seen, it doesn’t seem likely it wouldn’t be audible. Anyway, good units for other applications but not Klipsch networks. 
 

Someone asked about the wiring. The original wiring is tin annealed stranded copper.

[geezin']

And there ya have it...

[mboxler]

As already stated, the two biggest differences between the T2A and the others is the inductance and the -3.35db tap.  Of the two, I believe the inductance has the biggest effect.  Of course, the combination of  a "brighter" polypropylene capacitor combined with .35db less attenuation might be noticeable as well.

 

Even though all of the autoformers will result in a 2nd order high pass to the squawker, the inductance between taps 0 - 4 dictates how high in frequency the 12db slope extends.  The lower the inductance, the higher in frequency the 12db slope extends.

 

I can't find any published specs on the 3636, but one of them I have measures around 90mh between taps 0 - 5.  The published inductance of the T2A is 45.6mh +/- 15%.  A T2A I removed from an old Heresy measures 32mh.  Since the inductance between taps 0 - 4 forms the second order, the values are...

 

3636 45mh
T2A (spec) 21.2mh
T2A from my Heresy 15mh

 

Although my T2A may be an extreme case, you can imagine the difference the shunt inductance would make.

 

Mike

[Deang]

21 minutes ago, mboxler said:

Even though all of the autoformers will result in a 2nd order high pass to the squawker, the inductance between taps 0 - 4 dictates how high in frequency the 12db slope extends.

 

The curve for the 3636 did not look like 12dB/octave to me.

[OO1]

12 hours ago, Deang said:

The original wiring is tin annealed stranded copper.

what's the recommended   size gauge ?  Tx   

[mboxler]

16 minutes ago, Deang said:

 

The curve for the 3636 did not look like 12dB/octave to me.

 

I agree, kinda.  When I run the simulation with the 3636, the slope is 12db/octave up to about 100hz, at which point the slope starts to flatten out.  The steeper slope is there, it's just useless.  With a T2A, that slope will extend much further into the audible range.

[Deang]

24 minutes ago, OO1 said:

what's the recommended   size gauge ?  Tx   

 

16 gauge, but consider the capacitors and coils are 18 or 20 gauge. The runs on the board are so short I don't see how it matters. From the drivers I would use 16 gauge - which is what Klipsch used.

[KT88]

17 hours ago, henry4841 said:

Transformers are nothing more than wire usually wrapped around an iron core. There must be a different turn ratio on the replacement than the T2. Since you are playing some why not try some different settings on the replacement just for fun. I would be curious on the results. I am using the 3654, I believe that is the number, on my AA's that I built and am curious on your findings. I built around 30 different kinds of xovers for my speakers years ago and found some I liked better than the AA's but consider the AA's plenty good enough. It is what I am using now. None sound bad but I do not have a trained ear and do not know how a good Grand piano should sound like.

 

Any good solid copper wire 18 gauge or better would be ideal in my world. 

 

Good post.  

If you happen to have a T2A lying around, trade it for the 3654 in your LaScala just for fun. You are the best test candidate for the T2A because you have been used to the 3654 for so long now. However, based on my listening impressions, I think using polyester caps for the tweeter is even more necessary when paired with the T2A. Polypropylene types could really make the tweeter too loud with the T2A.
I'm into day 2 and my first positive impression from yesterday was not a short-changed showstopper just because it's "different". I got a lot more timbre, a great 3D stage and not a single 60's trumpet dissecting my ear.

[mikebse2a3]

20 hours ago, KT88 said:

Can anyone tell me which wire of the xover is closest to the original wire? Unfortunately the original wiring no longer exists. The same goes for the wiring of the drivers. What can I take there to get very close to the original?

 

Heinz I checked the driver wires which appear to be stranded tin coated and they appear to be slightly loose in the 18ga “stranded stripper slot” and tight in the 20ga “stranded stripper slot” so I would go with 18ga IMHO.

 

miketn