Tweeter cutout a bit too small - influence on the sound or not?

[KT88]

You can't see it so well on the photo. The cutout in the wood of my 1977 Lascala is noticeably smaller than the mouth of the horn. With the finger you can feel a clear edge. Is it ok (because the edge disturbs much higher frequencies than in the audible range) or would it be an improvement if I file and adjust the cutout in the wood gently?

 

 

[Marvel]

I would say it should be even. Really hard to front mount them, but at least even so opening isn't smaller than the horn mouth.

 

I front mounted my k-400s. First made a template out of heavy paper, traced the enlargement and used a router to open the baffle up a bit. 

[jason str]

Edit

[jason str]

4 hours ago, KT88 said:

would it be an improvement if I file and adjust the cutout in the wood gently?

 

 

Not going to hurt.

[OO1]

5 hours ago, KT88 said:

You can't see it so well on the photo. The cutout in the wood of my 1977 Lascala is noticeably smaller than the mouth of the horn. With the finger you can feel a clear edge. Is it ok (because the edge disturbs much higher frequencies than in the audible range) or would it be an improvement if I file and adjust the cutout in the wood gently?

 

 

 

if you can match the tweeter  opening to the tweeter lens --why not ? but I would unscrew  the tweeter lens first and check to see if the tweeter  was not centered correctly prior to screwing the tweeter , in the cabinet at the factory -

[KT88]

Randy, thanks for reply, it is centered, I know because it is too narrow on both sides, horizontally even if slightly more at the top but in a way that the screw hole positions are very ok.

Yesterday my original Alnico round magnet K77 returned from empowering the magnet. Of course the shop had to remove the lens with the coil to work just with the magnet itself and they know what they do with great reputation in this country, specialized on vintage gear. They reached 1.5 dB which does not sound so much but it could make a difference also re the higher frep. response. I will tell later on what I hear. 

 

So I thought to widen the opening gently before I swap them and dismount the K77M which did an interims job. I know it’s all about fun in this thread and possible increases in subtleties. I'm not going to transform a 44 year old speaker into the 21st century, and that's not the point here. But if grinding optimizes something I might actually hear...why not.

Especially the motor board for the T35 should be precisely worked because originally the T35 was intended as a diffraction horn and the motorboard is an indispensable part of its construction on which it was recommended to be mounted from behind.
Even if in the Lascala we have the horizontal arrangement of the T35, which spreads a little less horinzontally than the original vertical arrangement of the T35. But we had this topic horiz. vs. vert. sufficiently discussed here in the forum half a year ago. I am only interested in a proper geometry of the aperture for the lens.

 

I love it when something historic reads like the brand new innovation. It is somehow the point where science met marketing. See the link to this vintage T35 brochure.

 

http://www.cieri.net/Documenti/Istruzioni/Electrovoice - Tweeter T35, T35B, T350.pdf

 

 

Nice short read BTW concerning the lively history of the T35 tweeter.

https://audioxpress.com/article/remembering-the-electro-voice-t35-super-tweeter

[Deang]

So they remagnetized and got a 1.5dB increase? That's quite a bit actually. 

 

Just to be clear, your concern is that the horn of the K-77 is mounted behind the hole, and not flush mounted? I would not fret over this or hack my motorboard unless you can do a really nice job -- it's not worth it.

 

My OCD got the better of me, and I used some very thin felt, and lined the cutout to reduce the reflections that I couldn't hear, lol.

[billybob]

Glad to finally find out about the remag. result.

[jason str]

Did a bit of massage work installing mine too.

File and sandpaper over wood scrap.

[KT88]

4 hours ago, jason str said:

Did a bit of massage work installing mine too.

File and sandpaper over wood scrap.

So did you hear a difference in sound?

[jason str]

28 minutes ago, KT88 said:

So did you hear a difference in sound?

These cabinets were stripped when I got them. 

Big ridge or dip will make a difference no doubt.

 

[Marvel]

9 hours ago, Deang said:

So they remagnetized and got a 1.5dB increase? That's quite a bit actually. 

 

Just to be clear, your concern is that the horn of the K-77 is mounted behind the hole, and not flush mounted? I would not fret over this or hack my motorboard unless you can do a really nice job -- it's not worth it.

 

My OCD got the better of me, and I used some very thin felt, and lined the cutout to reduce the reflections that I couldn't hear, lol.

I think the concern is that the opening is smaller than the horn mouth.

[Dave A]

Opening it up can't hurt. However the straight wall tunnel the sound has to go through to exit the motorboard does hurt and there is no way to fix that. It is why Klipsch eventually went to the K-77-D and F type tweeters.

[KT88]

39 minutes ago, Dave A said:

Opening it up can't hurt. However the straight wall tunnel the sound has to go through to exit the motorboard does hurt and there is no way to fix that. It is why Klipsch eventually went to the K-77-D and F type tweeters.

I am not so sure about this because the T35 was designed to be a difractional horn which needs a motor board at the front even if the original measurements recommend a thinner board than the LaScala has. Here below is the description and the polar sheets because it was designed to be mounted vertically but it is not so much a difference and therefore PWK decided to mount it in the horizontal positioning so it fits into the case.

I am wondering if the D and F types really sound better without the board?

 

https://mypicsonline.net/archive/archives.telex.com/archives/EV/Horns/EDS/T35A EDS.pdf

[mikebse2a3]

34 minutes ago, KT88 said:

I am not so sure about this because the T35 was designed to be a difractional horn which needs a motor board at the front even if the original measurements recommend a thinner board than the LaScala has. Here below is the description and the polar sheets because it was designed to be mounted vertically but it is not so much a difference and therefore PWK decided to mount it in the horizontal positioning so it fits into the case.

I am wondering if the D and F types really sound better without the board?

 

https://mypicsonline.net/archive/archives.telex.com/archives/EV/Horns/EDS/T35A EDS.pdf

 

Heinz ……… I’ve made two observations about the K77 and K77M mounting (Flush with Baffle) versus (Behind the Baffle Mounting).

 

I had LaScalas with K77M mounted (Behind the Baffles) and Belles with K77M factory mounted flush with Klipsch Z-Brackets and my perception was clarity was improved with Flush Mounted K77M in the Belle .

 

I also had 79 Klipschorns later and based on my observations with the La Scala and Belles and the fact Klipsch made some changes to the Klipschorn at some period after Heyser’s Klipschorn review in Audio Magazine and his observations of the Klipschorn noted some clarity issues in the Squawker/Tweeter crossover frequency region which I suspected was possibly in part due to the diffraction effects of Behind the Baffle mounting of K77 and K77M tweeters. So I decided to purchase the Klipsch Z-Brackets and Flush Mount the K77 tweeters which did require enlarging the Baffle Opening for the K77 in the 79 Klipschorn. My observations and belief afterwards was that the clarity was improved on my 79 Klipschorns with the now Flush Mounted K77.

 

With that being said if I liked how the La Scalas are sounding to you now I can see leaving them original because good or bad it is a part of the original character of that model of La Scala and gives it a unique sound which should be taken as part of the a whole listening experience with them.

 

The K400 horn also has it’s own character when compared to more recently developed Klipsch horns like the K510 for example but I can still love them in my La Scala AL5 because the reproduction is still very engaging even if it does add a bit of it’s own character to the sound versus the K510 it is a lovely character that still is very engaging to me.

 

miketn 🙂

 

[KT88]

Mike, thanks for sharing your positive experience with installing the K77 flush with the baffle.
As you mentioned in this case I leave it original installed from behind.

But would it be another speaker that is not under the motto of recovered originality I would definitely try it.

Maybe the following is just a theoretical thought...Could it be that mounting flush with the baffle creates more clarity but that mounting from the rear gives the whole speaker more impetus and authority?
Anyway I think you would have noticed this immediately. I would love to have another outlaw besides the "original" Lascala with which I would try all this, all kinds of tweeters, all modern horns, also two-way tractrix as well as additional bass reflex boxes underneath etc.

[Dave A]

1 hour ago, KT88 said:

Maybe the following is just a theoretical thought...Could it be that mounting flush with the baffle creates more clarity but that mounting from the rear gives the whole speaker more impetus and authority?

Many like to flavor their music in certain ways. Tube amps are warm and mellow is a common refrain for instance. Does not mean they are truly lifelike in sound,  it means they are what the listener prefers which is what it is all about anyway. I want as close to real life as I can get and so I work on sound that, to me, is like what I have heard in person using stringed instruments like Cellos as a reference. The tunnel imparts a sound quality I do not like and I can't think of one speaker builder that does this with tweeters right now. Legacy speakers yes but not current production. 

 

 I have another one for you. I know a fair number of people who buy tweeters and then put them in stands to sit on top of their La Scalas where they time align them with the mid horns. I doubt my hearing is acute enough to hear that kind of difference but those who do this say they can.

 

  I listen now with EQ flat when listening to speakers with passive crossovers to attempt to get as close to real life as I can. Currently the only exception to that rule is with DSP where, like on my Super MWM's for instance, I have to time align and also work with drivers and horns that require settings to sound right. Impetus and authority take back seat to fidelity in my book as that is what I have watts for if I need them.