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'76 La Scala - ALK Universal to Type A???


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4 hours ago, KT88 said:

It's just my two cents. I bought the ALK universal network 16 years ago for my 1977 Lascala. I was not satisfied with it. It sounded "clean" but not so musical, I could hear the tweeter separately from the midrange when there was pink noise. Then I bought the AA network from Crites, which can be plugged into Type A. I like AA better, A was good on a 300B and a Leak Stereo20. But AA gives more definition. A is warm but AA gives me more speech intelligibility without sounding "cold" like ALK Universal does to my ears.
AA definitely sounds best on my MC275.
A is for low volumes, AA for soft to adequate volumes. The coherence is fantastic with AA.
About the tweeter, I had a CT125, that was more "hifi" sound. But the K77 does a much better job of a "unified voice". It's less hifi but more Klipsch with great timing and authority of sound, even if the K77 hisses a bit depending on the recording, I won't change it. I cannot speak about the newer iterations of tweeters mentioned here but if I were you I would build up everything Xover etc. before I would change the in my view excellent matching original tweeter. BTW Polyester caps do the magic in my view on an AA network as the original canned caps were also polyester types. The „Q“ of this caps seem to match the horns very good and it is certainly no coincidence that even the most modern, highly praised Klipsch Heritage speakers have these yellow polyester caps, as can be seen in photos on the Internet. For me the change to such a type was definitely an improvement over the whole freq. band after I had Sonicaps before.
With the AA crossover it is definitely the much nicer sound when the Zener diodes are not in the circuit. It's only a protection for very loud signals or when a transistor amplifier makes loud clicks when switched on and off. Type A is 6 Db to the tweeter, type AA is 18 Db but still inherent.

KT88,  I like your gear choice.  I will have a 300B amp someday.  I would be curious to know what Polysester caps would you recommend or that you have experience with in Klipsch XO's?  

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boleiro, have a look at this thread.

 

I am not a strict advocate of a faith community. I also think everyone should experiment until they find what they want. But in the case of capacitors, I followed what Roy Delgado posted here at some point. According to this, the polyester caps are those that harmonise very well with the characteristics of horn loudspeakers. Polyester caps are not as "precise" and the transitions at the ends of the frequency range of e.g. the midrange (which is only limited downwards) are softer than using polypropylene. Also the „ESR“ is higher with polyester caps. Normally it is common to reach a low ESR but then the originally intended impedance of the vintage networks is not achieved any longer which leads to a mismatch of frequency balance over the whole spectrum. I just tried it out and I am very pleased with the result. You can buy the capacitors from JEM but you can also put together the Polyester caps yourself. If the original values are not available, you can use standard values, at least for a first listening impression. For example, I need 13 mf for the AA network, but I bought 2x6.8 mf because they only cost a handful of dollars. And I'm still within the 10% tolerance that the original caps had. I measured my caps before installing them. 
Some people make a secret of the "Klipsch approved" caps, but they are simply polyester caps. I bought proper caps from Mouser. It's really worth a try. Instead of the required 2mf, I used 2.2mf. Of course the exact values are better especially because the 2 mf are connected in series behind the 13 mf, but I am very happy with the result. At JEM you get the same polyester caps, but with the unusual values of the capacity tuned to the Klipsch networks but also for unusual prices as far as polyester caps are concerned. To test whether you like it, I would first try standard values. One more point...when absurd money is spent on exotic caps, people like to talk about the break-in time and burning in. Believe me, this is just as true for polyester caps. Otherwise Steve Guttenberg wouldn't have done an extra review on youtube where he enthusiastically reports that his Cornwall Mk4s are still so much better after a year.

 

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Google search or search here on the forum for an A or AA schematic. Then compare to the ALK schematic and make the necessary changes. The A or AA uses less parts, so a conversion should be easy.

 

The change from ALK to A or AA will make the most sonic difference. The difference between cap types will be less audible. Choose a reputable brand cap and make the conversion. To start, I would recommend Dayton Audio poly caps or a name brand of polyester caps. Don’t get crazy with boutique parts to start. Just use “good” parts. 

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On 8/7/2021 at 8:21 PM, boleiro said:


 

Panelhead, I swear I talked to someone on this thread last night about replacing the tweeter with the DaveA SMAHL V2 horn and DE120 drivers. 

 

Those have to be heard to really be appreciated.  I have a pair of LSI's that I've heard stock.  They now have the original ALK universals and Daves walnut lenses with DE120's.  No way I'd ever go back.  I brought them to an audio gathering last year and all were genuinely impressed.  It's a magical combo.  Is it the original Klipsch sound?  Obviously not but to MY ears, it's much much better.

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On 8/8/2021 at 4:07 PM, boleiro said:

They sound awesome with the ALK xo’s… amd it’s not that I want to change the sound or that I’m looking for something. Different than we say, but I just can’t shake my curiosity of what the stock Type AA will do. 

Build a second set of Type As to compare.  Keep both and enjoy.  Use Banana plugs for quick swap out. 

 

 

 

6 hours ago, Marvel said:

Just wanted to point out that the ALK has a swamping resistor in the circuit, which helps provide a more even load for lower powered tube amps. You will just have to change to an A/AA to see if you like it better.

 

Yea but doesn't the resistor just burn up some of that low power? 

 

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4 minutes ago, tigerwoodKhorns said:

Yea but doesn't the resistor just burn up some of that low power? 

 

 

Yes and no... I used some 2A3 amps, 3.5 watts a side and never felt I was lacking anything.

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2 hours ago, CECAA850 said:

Those have to be heard to really be appreciated.  I have a pair of LSI's that I've heard stock.  They now have the original ALK universals and Daves walnut lenses with DE120's.  No way I'd ever go back.  I brought them to an audio gathering last year and all were genuinely impressed.  It's a magical combo.  Is it the original Klipsch sound?  Obviously not but to MY ears, it's much much better.

 

That makes sense. I have Dave's tweeters in my Heresy I pair, with an ALK Universal Economy crossover. I hope to do the same to original La Scalas. 

Add 10awg twisted copper wiring from the crossover to the drivers, and 10awg for the amplifier cables to the speaker inputs. It is a glorious thing.

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wow... I am all over the place!  Lots of great ideas have come from this conversation.  I have changed my mind more than a few times already.  But as per usual, I feel I have received some great advice and options on how best to proceed.  I think I'm set now set on a smart path.  I'll build up a pair of AA's.  I already have most of the Inductors needed, just need to buy the caps and a 245uh inductor.  I'll go with modest caps for now and see how the AA stands up to the ALK.  Once I decide on the XO I'll be getting a pair of the SMAHL V2's and compare to the K77.  And then by then I am sure I will have more ideas from reading too much on this board.  

 

 

 

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On 8/7/2021 at 10:15 PM, karlson3 said:

Re: DE-120 - is there a little cheap plastic  K77/T35  horn to fit that driver?zpYH4Ml.jpg

 

Here's an A configured network battery biassed before mounting the 9v battery holder.   IIRC DJK (R.I.P.) said the AA tweeter section could be converted into an "Acoustic Butterworth" with a 1uF cap spanning its two caps.

 

 

Hey Karlson, are those russian PIO caps?

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On 8/9/2021 at 10:29 PM, Marvel said:
On 8/9/2021 at 10:24 PM, tigerwoodKhorns said:

Yea but doesn't the resistor just burn up some of that low power? 

 

 

Yes and no... I used some 2A3 amps, 3.5 watts a side and never felt I was lacking anything.

 

I should mention, I'm not using one of ALK's crossovers. Mine is a DHA2 designed by forum member John Albright. A really nice crossover.

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Posted (edited)

Got all my Caps... thanks KT88.  I ordered the same caps you mentioned.

 

However, I have 2 copies of the TYPE AA schematic but there is a difference between the two.  One has a .4mh inductor on the squawker and the other doesn't.   The drawings are identical except for this one detail (and the zener's).  Should the AA have a .4mh inductor or not?

Type AA 2.jpeg

Type AA 1.jpeg

Edited by boleiro
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My three sets of  AAs from various vintages do not have the  additional inductor. 

 

I  believe the 0.4 mH was added by by forum member John Albright to tame the midrange for those that like a bit reduced energy in that frequency spectrum.

 

Cheap enough to try  it with or without  to see what your preference is.

 

 

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See the wire in the pic below that is wired to the input #1 terminal through the Squawker terminals... doesn't look like as though it is hooked up to the tweeter terminals.  I noticed here and looked around and see that it is on pretty much all Type AA XO's.  

 1493696001_TYPEEAAXO.thumb.jpg.ef8b156e063be0d65b3d551220ed3611.jpg

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On 8/8/2021 at 5:13 AM, Curious_George said:

 

My first listening impressions were underwhelming... My main source is a CD player. As much as I am an analog guy, I hate pops and clicks from vinyl. Very forward midrange, rolled of high frequencies and low bass output. These were in the corners of a small living area, out from the wall about 1 to 2 feet. The Heresy's actually had better bass, but not by much. I switched the midrange from tap 4 to tap 3 (making the cap change) and that helped a bit, but still underwhelmed.

 

Apparently that is the way they were designed and people either fall in love with them or modify them. I fell in love with them and modified them, and love them even more now. Nothing like a full horn speaker system. They are an acquired taste though, not for everyone. 

 

When I first got my 1974 La Scalas, I found them kind of “shouty”.  Reducing the midrange volume cleared that up, and now they’re very pleasant to listen to.

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Lots of discussions and in depth sound perceptions from those that have done some changing around. Played around with many different X-overs years ago and to be honest the differences between the ALK and A or AA is subtle at best. A small change in volume level can change anyone's opinion of which is better. In other words a volume increase comparing two electronic audio components can deceive you. For me doing away with the autotransformer and building a simple 1st order crossover network using resistors for attenuation sound best to me but that is another story. After experimenting with over 30 different X-over combinations I settled on the AA as being good enough even with the autotransformer. And and keeps my LaScala's stock making them easier to sell for my kids when the time comes. 

 

The OP says he does not listen loud so I honestly think he will be fine using the A network. If one likes the sound and something happens to the tweeters just replace them with ones that are not delicate like the stock ones. I like simple circuits and the A certainly fits the bill. 

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On 8/17/2021 at 3:32 PM, boleiro said:

See the wire in the pic below that is wired to the input #1 terminal through the Squawker terminals... doesn't look like as though it is hooked up to the tweeter terminals.  I noticed here and looked around and see that it is on pretty much all Type AA XO's.  

 1493696001_TYPEEAAXO.thumb.jpg.ef8b156e063be0d65b3d551220ed3611.jpg

It is definitely hooked to tweeter its the ground wire. 

I use type A in my Scalas all stock drivers. 

 use type A with 4500hz mod and crites early tweeter on my K=horns to take load off mid drive. Love them both.  

I had built ALKs a long time ago didn't really think they worth all the money spent on parts. I sold them if anyone has them my name is on bottom of them. 

So I wold recoment type A with caps from Crites or JEM...but i noticed his are on high side. 

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