KT88

Very comprehensive information here. So I will experiment for a while with the tweeter I have, the original K77 Alnico. I read a bit today about the history of the T35. I noticed a few things that I find interesting. Before I go into it, I did a simple test after my reading that I would like to briefly describe. You know that my issue is this hiss which you can hear with spoken S or sometimes with strings or cymbals. I was with my head close to one of the LaScalas tweeters and listened carefully and this annoying hiss is clearly audible. Then I turned my head 90 degrees, one ear to the ceiling and the other ear to the floor. This hiss was as good as gone. Why did I do this primitive test? I learned things on the net that were new and exciting to me. Before, when I was young and naive, I wondered why a horn (K77) is mounted from the back of the baffle, it was not intuitive to me because I thought the propagation of sound waves would be inhibited and disturbed. I was even confirmed (in my wrong thinking) when Klipsch mounted the K77M flush with the baffle in front in the early 2000s or when it was. Since today I know that the T35 was developed originally as a diffraction horn. It has even been relatively accurately calculated for installation behind! a baffle that is (normally less than) 3/4 inch thick, unlike the Lascalas boards. (see the specs in the link below). However, it was developed for vertical mounting. Using the 3/4 inch baffle, it actually radiates more than 100 degrees horizontally when mounted vertically due to the diffraction principle. At least that's how I read it. I'm not going to cut up my beloved Lascala but I will remove the K77 when I have time and place it vertically on top of the speaker behind a 3/4 inch baffle mounted. Of course I know that the distance to the K400 will be too big but I want to hear the intended principle of the K77 tweeter horn. I have fun dealing with it. So it's interesting and a nice development. If I didn't have this interest I could reactivate my Jubilees which are great, which I have listened to for 10 years without interruption, but the Jubilees are so good that I can't improve anything with the exception of testing different drivers or DSP settings. I found this interesting thread among others here in the forum. And the web has some good articles about the usage of the the T35/K77 horn. May be I am totally wrong and many others have tried what I intend to research re the different positioning of the K77 but anyway, I will see. May be the effect is not too huge whether the K77 is mounted horizonally or vertically but I would like to try it out. BTW EV recommends thinner motorboards than 3/4 inch but anyway. Here is the original EV spec sheet of the T35A/K77M incl. polar response, the long axes mounted vertically. https://mypicsonline.net/archive/archives.telex.com/archives/EV/Horns/EDS/T35A EDS.pdf

Yes, Marvel, the CT125 I have imported in 2009 from Bob (RIP). I will have a look at it.

It's not the background noise that I mean by "hiss", geoff. It is this added metallic tone when I hear cymbals for example. Years ago Al Klappenberger explained it here in the forum very vividly. The K77 sounds like Sssssssssss, a softer tweeter like Fffffffffffff. Of course that's not the only reason to choose a tweeter respectively what this thread is about. Many thanks to all for the explanation on the fit of the tweeter horns and magnet sizes. My gut feeling is that I will try the K77M first before trying other designs. Such parts can be sold again quite well if it does not like. I am of course very interested in this topic but I will postpone the tweeter decision a bit because I noticed today that my KT88s are very worn. The tubes have been running a lot since last year in March, partly because of Covid and all the time more I spend at home. I connected the amp today to conventional speakers with much lower efficiency. There I hear quite clearly that they sound thinner and shriller than normal, the meat is missing, especially in the lower mids, in the bass section anyway. I did not notice this so explicitly with the Lascala because you need so little amplifier power. But still, the sound of the amp is not as powerful and silky, likewise with the Lascalas. Therefore, before I modify anything on the tweeters the amplifier must be back in full juice. I have ordered new KT88 (the small tubes are fine and relatively new). Otherwise I'm in the fog and have no reference when judging the tweeters.

BTW would the magnet of the DE120 fit into the Lascala box when mounted on the CT horn or is it in same way slightly too big in diameter like the CT125?

Okay, theoretically the CT120 would also be an option. Since I have the CT125 I only need to buy the B&C DE120 drivers, over here for about 90€ a piece without customs because they come from Italy. To my knowledge, the Crites horn is the same for CT 125 and CT120.

Marvel, at first, thanks for your posts, I know, memory can be deceiving. At the moment I also have the impression that I should wait a bit, because since only 10 days I have the new capacitors in the Xover. And whether it's my psychoacoustical adjustment or actually a break-in process of the capacitors, or both...the sound is still changing a bit every day at the moment. But overall, I think the Alnico tweeter is playing not high enough in the frequencies because with the exception of the slight hiss the sound has become very natural with the new Polyester caps but the cut off of the Alnico gives less a 3D presentation in comparison to the CT125. But I would more sacrifice 3D than impulse and seamless presentation of the K77 series. If the K400 stands out a bit, maybe a K77M would perhaps be a good addition. It's fun to finetune so nicely. First and foremost, I'm very pleased that I'm going back to originality based on the AA takeover points.

I can understand the buyer/seller on the one hand because he might be afraid of the effort to get the parts the same for left and right. But on the other hand, I think it's a shame to spend so much time consulting. In the end, the advice and information from all of us on the value of the parts gave him the idea to make a quick deal. Sad for the speaker. On the other hand it will keep other vintage speakers alive

Thank you for your post. As I wrote I listened very extensively to a then new Lascala at a friend's house in about 1996. It had K77M and it didn't sound as noticeably like ham sizzle as my old Alnico K77s do these days. What would be your advice, buying new diaphragms for my Alnicos or better directly swap for K77M and collect the Alnico? I love Alnico magnets but the K77M have more magnetic force and therefore a higher frequency response and therefore a bit less hiss? This solution would please me very much because my speaker would remain largely original...

In my experience the CT125 is not so good integrated when I listen on-axis which is the most important listening position to me.. It may be liked very much by others and it is a high quality item but the „Klipsch sound“ is somewhat gone in my view, especially the homogenous attack in the whole freq. band. I have angled the speakers so that I can see the inside walls a hand wide from my listening place. This offers a 3D stage for my listening. But when I walk in the room the Lascala sounds „shot in“. I can imagine that the tractrix K771 solves this issue. Or may be a K77D as well?

I may not have searched the forum well enough but I have not found anything that answers my question. My concern. I reactivated my 1977 LaScala after many years and wrote something about it here the other day. My thread about the matching capacitors for example. Everything I say now is my own subjective opinion and I would like to emphasise that I do not want to criticise any supplier. It is my very personal choice of components that is at stake here. In the end, after some excursions like 16 years ago ALK universal Network or e.g. CT125 Tweeter, everything is very original again, with AA crossover, new capacitors and the original K77 Alnico Tweeters. Unfortunately, these tweeters are an extremely ambivalent matter. On the positive side, the K77 is the only one in my view that reproduces the impulse most closely, that articulates vocals most homogeneously together with the Squaker and that reproduces an acoustic guitar string in such a way that it sounds natural. But there are also less satisfying aspects. In its original state, my 1977 Lascala sounds very good when you sit right in the hotspot. Also, the three-dimensional depth gradation is very good and, for me, rich in experience. I could live with the fact that the K77s don't go very high in the frequencies. But what is a problem is that off-axis the speakers sound completely closed. It's just obviously the disadvantage of the original vintage style. In addition, off-axis there is this sound of frying bacon, this hissing that can spoil all the fun. Your recommendation would be very valuable to me What can I do. I don't want to improve it in a way that I get other disadvantages. To cut a long story short, I want a Klipsch Tweeter and not a third party solution. First things first. What is the improvement if I leave the tweeter as it is but I would have it flush with the baffle? Is the mounting from behind the board the cause of the hiss? Or is it the old phase plug? Should I buy a K77D like this, i.e. one that closes off at the front and is a newer version...with a ceramic magnet? (I always thought I loved Alnico). I heard a 1996 Lascala at a friend's house some time ago. It had K77M classically mounted from the rear, I don't know which Xover. But it didn't have that hiss in my memory. Or should I just buy a new diaphragm? Can I theoretically use a new K771? I am very sure that the K771 was designed in such a way that it harmonises with the K400/401. The aim was to get the best out of Lascala and Khorn without changing the K401. That is Roy's ambition. It is the true heritage of PWK and that is why I am very sure that the K771 was designed with that in mind. It would certainly have been easier to use a new midrange horn. But the K400/401 has very fantastic qualities in my experience. It was developed by PWK for the Atlas driver and I love the sound. Three questions. Is it possible to buy the K771 as a single part from Klipsch? Does the K771 fit mechanically into the vintage Lascala cabinet? Could I run it with the AA crossover...even if I didn't use its ability to play well above 4500 Hz? Or would I have to use a modern contemporary crossover? After all, the K400/401 with the K55V is the reassuring constant in all considerations, it's the same...then and now. Or should I leave everything as it is and buy another modern Lascala? I hope it was not too much text and that some of you understand what my goal is.

Sorry guys, I don't want to contribute to the escalation here. But it is like this. The old Aerovox caps were polyester in oil. The caps that Klipsch uses today are also polyester caps, although without oil. This is really no secret. You can buy these caps at JEM or you can get them elsewhere. And if you are happy with Sonicaps, you can use Sonicaps or completely different caps. My goodness. Everyone can choose what they like. I personally favour polyester types with my old Klipsch Lascala. But from my point of view there is no reason to compulsively follow a holy rule. The advantage of JEM is that they offer the right capacitance values, some of which are not standard values. But they are normal decent good polyester caps. No more and no less. It is a very positive feature that PWK has always liked to work with sensible parts. So you take these sensible parts as they exist in today's incarnation. In my view, there is no need for reverence, but ignorance would also be wrong. And in the end, it's not worth arguing about at all. Do we want to have fun and enjoy listening?

I would take Polyester (Mylar) caps because they have similar properties to the original ones, I was less happy with polypropylene types but thats me. Here in the forum is the offer by JEM of Mylar caps you could get a set for your model of Klipsch approved caps in the pinned part of this section to be very sure, but other Mylars of same value should be ok at least as a try. So did I with my Lascalas. Klipsch also use Polyester caps in the current new range of Heritage speakers with great success as one can see on actual pics of the xovers. The horns like a bit a softer Q of this caps.

To be honest, the two K77 Alnico tweeters alone are worth $100 or more. Is the K55V with soldered ends or spring contacts?

Hi SpeedLimit, that sounds reasonable, it is not a big risk regarding the price. If the coils measure correctly but the diaphragms are no longer good, you can always remove them later and photograph them to see if they fit and buy replacements from Michael Crites (also via ebay) or similar dealers. I don't think Atlas used different diaphragms but I don't know. One note. At least the new PD5VT has a ceramic magnet as you can read on the homepage, that would be a disadvantage for me. I don't know how it was in the past (were there ceramic magnets existing at that time?). Maybe someone who knows them well can help. Or you try in addition in other forums as well. It's a pity that you have to pay so much customs and freight, because brand new PD5VH with Alnico like Klipsch is using again nowadays can be bought for about 330€ a pair e.g. in Germany.

Sorry for this, SpeedLimit, then I have to apologize as I did not know the circumstances exactly. IF the drivers should have transformers you could perhaps put them out of the signal way and I see no hesitation just to try this drivers if they work and if they sound nice. 16 ohm is that what we always get from Atlas drivers of any generation in Klipsch speakers. I am no expert but I think this transformers are used instead of an low ohms output transformer of e.g. an tube amp, when signals have to travel over a longer distance like in a huge stadium if they still have centrally based amps. Then it is less loss to send higher voltage to the driver which finally transforms into current just before the voice coil. Could you make a deal with the seller to try them out and if they do not work you could send them back? Is it like in a small town where all people know each other?

And B&C or Faital products should be even cheaper made in Italy than in the US. Good used Atlas also is no problem, also the new ones are not overpriced in the EU if purchasing from EU dealers.

Atlas offers similar looking drivers still today. I would take care if the old drivers in your picture have transformers built-in, therefore the big housing at least in their current line up if you have a look at their page below, and if a driver with a built-in transformer is that what you need May be I am wrong and the reason to have this huge housing was different regarding the old drivers in your pic.. https://www.atlasied.com/loudspeakers-horn-loudspeaker-drivers-compression-drivers

My 2 cents is that it's not that easy to tonally fine-tune a speaker cabinet in the service of musicality. I'm afraid it's far too easy to say, well knock some bracing into the box. Should (unintentionally or uncontrolled) resonances of higher frequency arise which can also be very ugly? The various manufacturers have put a lot of thought into keeping the musicality intact. And so certainly Roy with the CW, also the acoustic fingerprint must be preserved when a model has such a long tradition as the CW. I think the art is something like the "contemporary adaptation". Maybe a Pepsi tasted different 40 years ago than it does today, but it tastes in the world of today in such a way that it is "experienced" as it was poised in the competitive environment 40 years ago. Maybe a CW should be less "boomy" today than it was 50 years ago, but it shouldn't suddenly sound like an antiseptic sound-dead sterile box that is no longer acoustically sexy in the way a CW should be. There are so many examples of aggravation. Especially with conventional cabinet shapes like closed or bass reflex. Sandwich filled with sand, slate, concrete, swapping struts etc. etc. The CW has certainly been adapted very carefully and lovingly. In the photo I have another example of a well done cabinet in my view, my Tannoy Canterbury. The vertical narrow side openings are a sort of bass reflex opening that you can slide open and closed. The horizontal board with the 4 round holes is a brace from front to rear and there is from left to right a vertical mounted board in the middle between the holes. Whether this is all "scientifically correct" I do not know but the box does not drone and it sounds warm, controlled tuneful and musically alive in the entire bass range. The BBC boxes I also like very much in the sound behavior of the bass and the upper bass. They use thin birch plywood paired with bitumen panels inside to change the acoustic travel times or sound speed coefficient. The backs are screwed in only very loosely, creating an effect like a church bell that has a crack and no longer sounds or resonates (where to resonate is desired with the bell). The cabinet is therefore virtually interrupted in the formation of the resonance (which is again desired in that case). Many "modern" designs of enclosures try to suppress sound from the inside by using particularly thick and massive enclosure walls. But mostly they achieve a very unattractive effect. They simply increase the time until the sound escapes from the housing. The brain interprets this as an ugly time smear that sounds like annoying discoloration. The BBC design, on the other hand, decreases the time for sound to exit through the walls. The Cornwall is a classic cabinet that similarly prefers to take some resonnances but not kill the sound. That is why it has a lively sound. Ok this BBC conception is suitable only for smaller volumes but in that region it is very good, some of you will have heard a little BBC LS3/5a or a LS3/6. Another example is my beloved Fender Bassman guitar amp. Here, of course, the goal is not hi-fi but a deliberate sound. It has four 10 inch drivers on the baffle. The baffle is only screwed with four wood screws in the corners. Thus, the whole baffle vibrates when you turn up the amp to bursting (but also when you play quietly). In all decades there were wiseacres who wanted to fix the baffle of the Bassman "properly". With that, the sound was dead. To sum it up there are very interesting approaches and also some that I do not accept so much. But it's not as easy as it seems. No bass horns but still a challenge where a layman might think it's just a casing. I count the traditional Klipsch designs CW and Heresy among the very interesting and authentic speakers. I must admit that I have not heard a Cornwall and Heresy of any generation yet. But I am very interested to hear a CW4 finally and I fell in love with the Heresy4. A speaker I should always find a room for. Heinz, Cologne

Once independently of the topic of the line array, here in some post it is considered that one turns the Lascala by 90 degrees. Many participants here will know this, but perhaps not all. That is why I am posting it again. When the Lascala was conceptualised, PWK had thought of the issue of thin side walls. He was of course very forward thinking in his way. Here are sketches of the various uses of the Lascala. For stereo use at home, PWK originally wanted to dampen the side walls by setting them up as shown in the picture. At least that is what I suspect. And by a whisker it would have looked like this for almost 60 years. If I should find a completely battered Lascala that can hardly be made beautiful any more, I would like to give it a try.

I am not so sure, Islander. If you google Hifishark, the prices for vintage Lascala are seriously risimg.

You did a super fantastic job, Anita. What a beautiful resurrection. BTW I also have 1977 Lascala and the emblems were missing. I purchased them in 2000. In 2001 I mailed at Klipsch and asked for new emblems, to my surprise they sent them even without charge…to Germany! I was so happy, it was so kind. Here I learn that the Laser emblems were in use in 1977 but I got happily the other type, no wonder when I follow the story of HDBRbuilder. In 2006 I restored them. Meanwhile they have the original Type AA crossover, at that time of restore I tried ALK for a while. Here is my thread from 2006.

I totally agree with you on that. I would take the beautiful older models without a second thought. The crossover can be reconsidered or replaced at your leisure. I don't know which squaker driver was used in that vintage. To be honest, the Lascala look so good that I would invest the money for an AA replica but with polyester caps and, find K55V for which this AA xover was made. It's much easier to modify an xover, or invest in the right driver sometime later than to spruce up such a rundown black box....

The following is not a recipe or a recommendation, I am just sharing how I do it, whether it is objectively "correct" I don't know, but it helps me. I have learned over several years that the addition of different listening scenarios works well. When I want to listen to the speakers respectively the modification, I first do it for a long time in mono, only one speaker altered. I don't switch back and forth frantically, but I listen a whole piece of music first on one loudspeaker and then on the other. Then the next one. This gives me the basis for my impressions and the descriptions as above in the first post. I note certain points in the music pieces that are particularly noticeable, e.g. a clear metallic sharpness in one of the speakers or the gain in timing and speed in the other speaker. Then I listen to these short parts again in direct comparison. When I'm done with everything, I'll have listened to both speakers together with a mono signal. In the case of this test, it was striking that the centre was totally lost. Instead of a defined centre, I heard a very cloudy pseudo-space that can only be explained by clear phase shifts in relation to each other. In my interpretation, this means evidence that the phases with the new capacitors 'inside' the one loudspeaker, i.e. the three drivers in relation to each other, also run differently because the shift is not linear from low to high freq. It is more like a confusing impression. So there is more change than just a different 'sound' of the capacitors. They do more than that re the phase shift. This is how I explain why there is more punch and attack although the speaker sounds much smoother and more pleasant at the same time when the drivers are more „in tune“ altogether. For example, male voices have less disturbing resonances which I would have previously explained exclusively by the thin side walls of the Lascala. These are still thin and resonate, but the resonances are less disturbing because they are more time aligned. In the end, I hear stereo for the first time after I have also fitted the second box with new capacitors. In this case, critical listening was no longer possible because the grin didn't disappear from my face.

I wrote it without a fee😀

I didn't want to advertise specific brands but it's not a secret. I use Kemet and Nichicon. Both brands are described in forums as good quality. It is what I could get from Mouser in this case. I also deliberately did not use Genteq or similar (cans of oil) because I wanted to stay close to the type recommendation of Klipsch. I'm all about the principle at this stage. The orignal Klipsch certified capacitors cost me over 220€ until they are in Germany because shipping, customs and VAT are very high. That's why I wanted to try first.