1973 Klipschorn Type AA resoldered with significant improvement.

[KT88]

I am gradually restoring my 1973 KH, which is new to me since the beginning of June. Today I renewed all soldering points, sucked off the old solder and applied new solder. Especially on the autoformer, where the original soldering points were almost the size of a pea. I also treated all the xover cable shoes that go to the inputs and outputs in the same way. My goodness, what can I say? I would not have thought this very significant improvement possible. That's why it's good that I approach all changes slowly and over weeks. The sound is much more detailed, much more analogue resolution, significantly more fullness in the K400 but also a deeper fuller bass. It's much smoother but at the same time more musical. While there were a few frequencies where it sounded thin and where I avoided higher volumes before, it's now so much more pleasant to the ear. It's not a small improvement, but almost a sound transformation. When I'm in the next room, I can hear speech clearly even at a very low volume, which was not possible before. Speech intelligibility is a big plus. The highs are also more expansive and silvery, once again a plus point for the K77, which is often the culprit but in reality sounds much better when the contacts are all fresh.

There is a strange discovery. The T2A is installed differently in both xovers. But I assume that if you see the connections, the autoformer in one of the two xovers has been turned 180 degrees in its metal frame? The connections are wired accordingly; if I were to turn one of the two T2A 180 degrees, they would be connected the same way. Unfortunately, you can't see any numbers on the taps. The K400s sound exactly the same and there are no phase differences. 

 

 

[KT88]

Oh, this thread should be in technical/restoration, but never mind, now it's here.

[babadono]

Ah...what am I seeing...so the windings are 180 degrees flipped in the core? is there a way to check/measure to make sure this is so? @Deang? @mboxler?

And if so aren't the Red/White and Black/White wires swapped on one of them? I see the Red/White in the middle tap on one then on the flipped one it's on the bottom Am I confused?

[KT88]

27 minutes ago, babadono said:

Ah...what am I seeing...so the windings are 180 degrees flipped in the core? is there a way to check/measure to make sure this is so? @Deang? @mboxler?

And if so aren't the Red/White and Black/White wires swapped on one of them? I see the Red/White in the middle tap on one then on the flipped one it's on the bottom Am I confused?

Yes, I just noticed in the photo that the red and black wires are connected the other way around (if the assumption about the 180-degree rotation is correct). Besides, one T2A is much more rusty than the other one. What mH values would I get for the two Autoformer transformers if I measured them? It's absurd, but they both sound the same to my ears but maybe not quite?

 

Assuming that the two T2A units are the same, which of the two is connected correctly? Unfortunately, there are no figures at the taps.

[KT88]

So the original Klipsch T2A is connected to my Crites LaScala crossover. 

It corresponds to one of the Khorn xovers. The red wire (if it were original) the middle tab also goes to the plus output to the K400.

 

[babadono]

It's Heinz correct? Hoping @Deang or @mboxler will see this and jump in. They know this stuff much more than I

[KT88]

Thanks al lot, babadono👍🙂

It's late here, but I've already removed the ‘wrong’ crossover again. Unfortunately, I'm afraid that I can't measure anything mH while the wires are connected. If nobody answers soon I'll just connect the T2A as it should be and then I'll listen carefully at a low volume (because I'm impatient and nervous). Indeed, when I'm consciously listening to them both mono one and then the other, it seems that the speaker with the ‘correctly’ connected T2A sounds clearer when speech is present.

[mboxler]

2 hours ago, KT88 said:

I am gradually restoring my 1973 KH, which is new to me since the beginning of June. Today I renewed all soldering points, sucked off the old solder and applied new solder. Especially on the autoformer, where the original soldering points were almost the size of a pea. I also treated all the xover cable shoes that go to the inputs and outputs in the same way. My goodness, what can I say? I would not have thought this very significant improvement possible. That's why it's good that I approach all changes slowly and over weeks. The sound is much more detailed, much more analogue resolution, significantly more fullness in the K400 but also a deeper fuller bass. It's much smoother but at the same time more musical. While there were a few frequencies where it sounded thin and where I avoided higher volumes before, it's now so much more pleasant to the ear. It's not a small improvement, but almost a sound transformation. When I'm in the next room, I can hear speech clearly even at a very low volume, which was not possible before. Speech intelligibility is a big plus. The highs are also more expansive and silvery, once again a plus point for the K77, which is often the culprit but in reality sounds much better when the contacts are all fresh.

There is a strange discovery. The T2A is installed differently in both xovers. But I assume that if you see the connections, the autoformer in one of the two xovers has been turned 180 degrees in its metal frame? The connections are wired accordingly; if I were to turn one of the two T2A 180 degrees, they would be connected the same way. Unfortunately, you can't see any numbers on the taps. The K400s sound exactly the same and there are no phase differences. 

 

 

 

That is so bizarre.   Do you have an LCR meter?  If so, I'd measure the inductance between certain taps.  You may need to desolder the autoformers to get accurate readings.   The inductance between taps 0 - 3 should equal the inductance between taps 3 - 5.  The specs say 11.4mh, but it's usually lower.  

 

The spec sheet shows other inductance values that should help determine which tap is which.

 

Mike

 

 

[KT88]

1 hour ago, mboxler said:

 

That is so bizarre.   Do you have an LCR meter?  If so, I'd measure the inductance between certain taps.  You may need to desolder the autoformers to get accurate readings.   The inductance between taps 0 - 3 should equal the inductance between taps 3 - 5.  The specs say 11.4mh, but it's usually lower.  

 

The spec sheet shows other inductance values that should help determine which tap is which.

 

Mike

 

 

Thanks Mike. I just tried connecting the ‘incorrectly’ wired Autoformer as it should be by default, see photos, before, after. But unfortunately the K400 is now much too loud on that channel. The balance is gone. I'll definitely take the measurements you suggest. The funny thing is that I had the impression, after seeing the original different connections, that the left speaker sounded slightly different from the right, not louder but different (the way I bought the speakers), but maybe that's just my imagination because I just discovered that the autofomers are wired differently.

It's late here and I'm going to bed now. Tomorrow I'll measure the induction according to your instructions. I still have the two original T2A from 1977 from my original LaScala crossover (which unfortunately is incomplete) on the Crites crossover of my LaScala. I think I'll use these T2A first because they are the same and sound good. Then we'll see what's going on with these Autoformers that are on my 1973 Khorn. It looks like everything looks fairly original, very strange.

 

 

[babadono]

2 hours ago, mboxler said:

The specs say 11.4mh, but it's usually lower. 

Lower than the spec'd tolerance? @KT88 told you these guys know more than me

[babadono]

I have some AA nets that I no longer use in storage. If you need me to check (double check, triple check) anything I'll dig them out.

[babadono]

@mboxler why is the -3 setting in quotes? Is that the factory setting?

[babadono]

I see it now in the AA schematic...-3dB is the factory setting..Tap 4

[KT88]

Guys, I couldn't sleep (wonder why), so I checked it out. Fortunately, tomorrow is not a working day for me.  @mboxler  The ‘correct’ T2A shows 7.83 mH between tab 0 and 3 and 8.26 mH between tab 3 and 5. However, I did not unsolder the connecting wires here. The values seem to be within a plausible range and relatively equal between 0-3 and 3-5.

The ‘strange’ T2A was desoldered, I wanted to measure it exactly. If I measure it the way you would normally do it, assuming that 0 is in the middle on the left, I get 2.89 mH from 0 to 3 and 0.41 mH from 3 to 5. If I measure it turned 180 degrees , I get 6.18 mH from 0 to 3 and 7.46 mH from 3 to 5. These seem to be plausible values, even if they are not exactly the same. By the way, I measured my other T2A from 1977 for comparison. 6.21 from 0 to 3 and 6.41 from 3 to 5. So also far from 11 mH. However, here also with connection wires.

So Klipsch connected in 1973 a T2A that was turned 180 correctly after all, and I was confused for nothing, except that now, with your help, I know that everything is ok. @Babadono, the cable colours were also reversed on that crazy crossover, but the connection points are correct. Here are a few pictures in case it works. First pic shoes that also the wire colour was mismatched @babadono

 

 

[Deang]

I have a flamethrower. 

[mboxler]

1 hour ago, babadono said:

@mboxler why is the -3 setting in quotes? Is that the factory setting?

I assume it’s because it’s actually -3.3db???

[mboxler]

Just to show that an autoformer is just a tapped inductor connect a known inductor in parallel with taps 0-5. You can then use an inductors in parallel calculator to verify the results.  This is exactly what Klipsch did with the AK3. The 5mh inductor is in parallel with the 7.6mh(?) T4A taps to get to the desired 3mh shunt inductance. 

[Deang]

I wonder how rusted laminations impact inductance. 

[mboxler]

1 hour ago, Deang said:

I wonder how rusted laminations impact inductance. 

I was wondering the same thing. Or loose windings?

[babadono]

Kinda off topic...isn't the core coated/impregnated with enamel to protect it from rust etc....?

And I don't know about loose windings but loose women change my inductance....might go from a microhenry to a macrohenry