Lascala cabinet resonance

[OO1]

total BS   there were no serious issues with resonance from the LS cabs , resonance was a tad noticeable  with the 200W Lascala Industrial speakers when they were pushed hard  and klipsch resolved the issue by beefing up the LSI cabs in the early 80's , I own the LSI  .

 

more BS   there was no problems either with the 1/2 inch  Heresy 1 or Cornwall 1 rear panels  or there would have been thousands of threads on the subject over the years   , I also own the Heresy- Cornwall  with 0 problems .

 

 

Edited December 18, 2023 by OO1

[Marvel]

9 hours ago, KT88 said:

Or is it more not to have used them about the issue that not all LS are identically built and there a one brace fits all has not worked?

This was what was reported by a former Klipsch employee. The braces had to be hand fitted and was cost prohibitve.

[Invidiosulus]

1 hour ago, OO1 said:

total BS   there were no serious issues with resonance from the LS cabs , resonance was a tad noticeable  with the 200W Lascala Industrial speakers when they were pushed hard  and klipsch resolved the issue by beefing up the LSI cabs in the early 80's , I own the LSI  .

 

more BS   there was no problems either with the 1/2 inch  Heresy 1 or Cornwall 1 rear panels  or there would have been thousands of threads on the subject over the years   , I also own the Heresy- Cornwall  with 0 problems .

 

 

That’s really funny.

 

[OO1]

12 hours ago, Invidiosulus said:

That’s really funny.

 

 

not so fast ,   one installs braces to tame resonance in the LS bass bin  , but ,  in reality the braces reduce the bass output of the LS bass bin    

 

 

[KT88]

6 hours ago, Invidiosulus said:

Randy is full of misinformation.

 

The top and bottom of the LS 

bass bin are adequately braced.

It is only the large side panels that are an issue on the LS 1.

Just like the 1/2” thick back panel on a Heresy 1, the side panels on an LS 1 will muddy the upper bass from its vibration if played at a louder volume.

my LS cabs were stock thickness 3/4” and the braces provided a noticeable difference in clarity.

Would I have gotten similar results from increasing the thickness of the sidewall?

Perhaps, but the braces were a cheap and easy install compared to increasing the sidewall thickness.

 

 

 

I will see if it will work with the braces even when the side walls are thinner than intended as the only measure, anyway, thanks for sharing your positive experience..

[KT88]

@Flevoman I actually only wanted to draw attention to the old La Scala 1 for a single reason, the history and origins, so to speak, of the significant resonance of La Scala for some people. And that in my case I never had any complaints about the La Scala 1 before the wrong treatment of the side panels. 

This actually means that theoretically the La Scala 2 should have even less resonance due to the material thickness (we should be able to hear LS 1 and 2 in direct comparison).

But that doesn't mean that it's not noticeable or even annoying with the La Scala 2 in individual cases. And that's what this thread is about. Sorry if my "diversions" turned into a "thread drift". 

 

In relation to the La Scala 2, if other causes such as room modes can be ruled out...is it possible that the fact that the La Scala doesn't have such deep basses could mean in some cases that the ear can become more sensitive to the higher basses, so that a disturbing effect of a resonance is amplified in the awareness but is eliminated as soon as the mono Klipschorn is integrated into the stereo system (if that is still your plan, Flevoman)?

[Invidiosulus]

4 hours ago, KT88 said:

I will see if it will work with the braces even when the side walls are thinner than intended as the only measure, anyway, thanks for sharing your positive experience..

Typically when a material decreases in thickness the amplitude of the resonance will increase and the Q of the resonance will decrease.

So not only will the resonance be louder on the thinner piece, it will be resonating across a broader frequency.

 

I measured this on the backs of my H1 with a small piezo transducer mounted directly on the wood while running frequency sweeps in REW.

Increasing the thickness will reduce the amplitude but the peaks will still be in the same place although narrower.

 

All of which is to say, I would imagine the AL5 sidewalls would resonate at around the same center frequency as the older models since the sidewalls are approximately the same size.

But since they are thicker they should resonate less and over a narrower range.

[KT88]

1 hour ago, Invidiosulus said:

Typically when a material decreases in thickness the amplitude of the resonance will increase and the Q of the resonance will decrease.

So not only will the resonance be louder on the thinner piece, it will be resonating across a broader frequency.

 

I measured this on the backs of my H1 with a small piezo transducer mounted directly on the wood while running frequency sweeps in REW.

Increasing the thickness will reduce the amplitude but the peaks will still be in the same place although narrower.

 

All of which is to say, I would imagine the AL5 sidewalls would resonate at around the same center frequency as the older models since the sidewalls are approximately the same size.

But since they are thicker they should resonate less and over a narrower range.

That sounds plausible and physically correct. Now I assume that the sound generated by compression in a horn is still loud in relation to resonances, even if the La Scala actually has a large side surface that has to be taken into account. 
So even with normal radiators we have a large Q with lower but sharp resonances at thick boards vs. a small Q at wide and louder resonances at thin boards. 
Another factor is the storage of the sound and its delayed transmission with thick boards, which can lead to time smeared sound,bit not an issue with horns or bass horns. BBC research started with thin-walled boards covered with bitumen of the same thickness. This damped the resonances well and there was hardly any time smear. Since everything in the world of sound is a compromise, these BBC cabinets don't work at all at seriously high volumes.

[Flevoman]

A lot of comments, some of which are certainly valuable. Thanks to everyone for thinking along and sharing experiences. The knowledge and help on this forum are truly superb 👍🏻

 

I started this topic with the question of whether the AL is known for resonance problems at certain frequencies. After reading all the answers, it is clear to me that this is definitely not the case. That means I shouldn't look for the issue in the speaker itself but somewhere else. Perhaps standing waves could be the reason? . I'll use the upcoming holiday to rearrange the entire living room so that the speakers are positioned lengthwise. I'll also reinforce the sides of the bass cabinet with a plank and clamps. I don't expect this to improve anything (since the conclusion is that the speaker doesn't have known resonance problems), but it's a small effort, and I want to rule out everything.

 

As for future upgrades @KT88, no... I've let go of the Klipschorn as I don't have corners to place them in. That would mean I have to place them against the long wall, and everyone here advised against it. However, I am eagerly looking forward to the upcoming Heritage Subwoofer series. I have high expectations, and I hope this will be a nice upgrade.

 

It might not come across this way, but the AL-5 is definitely not leaving. I enjoy these speakers every day and find them truly amazing as they sound now. Despite the annoying resonance I can hear in some songs at a certain frequency. Even if I can't solve this, I'll keep these speakers because of their musicality. But of course, my hope is to get rid of this last blemish. 😉

[Flevoman]

I want to share some experiences and thoughts if that's OK, and I'd love to hear what you think about this.

 

Years ago, when I first started this hobby, I had the LaScala 1 paired with the Dynaco ST70 II. Back then, the internet was barely a thing, I had no friends who shared this hobby, and my only gateway to this hobby was a small audio shop that didn't deal with Klipsch or tube amps. Through them and a series of connections, I could gather information or get equipment. Regardless, I was advised to modify the Dynaco with KT88 tubes. After submitting the amplifier, when I got it back a few weeks later, the sound was very unpleasant – dark and with a bothersome resonance (similar to what I hear now but much stronger). I'm unsure if the modification was poorly done or if it was supposed to sound that way, but I increasingly grew frustrated with the dark sound and resonance. It's been so long that I can't remember if there was already resonance before the modification and if it only got worse afterward. In any case, after the modification, the enjoyment dwindled, turning into frustration until I eventually stopped the hobby. I was young, less vocal, had no internet support like now, and the audio shop couldn't help. This led to the LaScala being stored in the garage for years, while I listened to a Sonos set.

 

Now, revisiting this hobby with more resources, I've often read about the LaScala 1's resonance. Every time I read about it, I thought, 'Yes, I recognize this.' However, now that I hear a similar resonance with the AL-5 (though significantly less), knowing that this speaker is not known for resonance problems, I begin to think that the resonance I heard with the LaScala 1 may not have been related to the speaker. Perhaps the Dynaco modification exaggerated an existing issue, but the cause isn't the speaker.

 

So far, this all makes logical sense. But here's the confusing part (at least for me): Before buying the AL-5, I was torn between the newest Khorn or the LaScala. I had the opportunity to listen to the Khorn at someone's home. While listening, I immediately heard something I hadn't heard in all those years – that annoying resonance at precisely the same frequency in a specific song. I only noticed it in one song, but it was unmistakably present. And this is challenging to explain. Is this something inherent to the LaScala/Khorn that I'm particularly sensitive to, or do this person and I share the same issue?

 

By the way, I can best describe the sound as something similar to the boomy quality sometimes found in deep bass in some speakers. The bass tones sound well-balanced, airy, and then at a certain frequency, something goes wrong, and you have a boomy sound. That's roughly how the resonance sounds here and with that person, but in the mid-low frequency range.

[babadono]

A standing wave? At some particular frequency manifesting itself? Bass is a _itch in rooms, just the way it is, physics and all. We will only hear perfection in Heaven.

[OO1]

36 minutes ago, Flevoman said:

 the cause isn't the speaker.

 you can verify whether the woofer screws  in your speakers are screwed tight .....remove the lower woofer access panel , and check the K-33 screws 1 by 1  , woofer screws that are slightly loose  can cause a vibration or resonance when playing music  , I'm not saying it is the problem , but it's worth checking .

[mikebse2a3]

2 hours ago, Flevoman said:

I immediately heard something I hadn't heard in all those years – that annoying resonance at precisely the same frequency in a specific song. I only noticed it in one song, but it was unmistakably present. And this is challenging to explain. Is this something inherent to the LaScala/Khorn that I'm particularly sensitive to, or do this person and I share the same issue?

 

I’m curious can you share what this “specific song” is and at what “specific points in the song” you are hearing the “ annoying resonance”.

 

I assume you have listened to this song on other systems or even headphones also and have not experienced the “annoying resonance”

 

miketn🙂

[KT88]

I assume that you, Flevoman, also hear this resonance in other songs. But it would actually be very helpful to know it in this specific song, and at what point in the song, in order to be able to understand it in my home. Not with the intention of relativising your perception, but to get an idea of which constellation of sound it is in which minute. 

 

I don't want to anticipate anything, but if the issue is centred on a few songs or even one, I have another idea. There are recording peculiarities that, crazily enough, only come to the fore with a high-resolution speaker like La Scala. That's why it's important to be able to distinguish between what's part of the recording and what's part of the LS.

[Flevoman]

Very good suggestion 👍🏻. It's too late now; I'm going to bed, but I will indeed search for songs tomorrow that have this resonance in them on my system. I'm very curious to hear what you'll experience then.

[babadono]

How's about hook up REW, turn on the sig gen and find the annoying frequency? Just an idea. And does the annoyance change as you walk about.

[Flevoman]

5 hours ago, babadono said:

How's about hook up REW, turn on the sig gen and find the annoying frequency? Just an idea. And does the annoyance change as you walk about.

 I have no idea what you are talking about, sorry 😄

REW, sig, gen...what does these words mean? 

[Invidiosulus]

8 minutes ago, Flevoman said:

 I have no idea what you are talking about, sorry 😄

REW, sig, gen...what does these words mean? 

REW is Room EQ Wizard, a free software that can be used to help tune an audio system.

It has a signal generator function that allows you to output sine waves(or white/pink noise etc) to pinpoint certain issues.

 

If used with a calibrated microphone such as the usb style UMIK, the software can be used to run frequency sweeps and give you measured results of frequency, group delay, etc.

All things that can be really handy.

 

I believe some of the group delay and waterfall style frequency/time plots would be helpful for actually measuring resonance vs input signal.

 

But, you really need a calibrated mic to take advantage of it.

[Flevoman]

Ahhhh.. Thank you for the explenation 

Unfortunately I don't have anything like that. 

Perhaps in the future I will by a mic for doing tests like this. 

But I did try a Hertz sweep to find any reconance somewhere. 

The only thing I heard where 3 small dips but not the sonic resonance I am talking about. 

[Schu]

On 12/18/2023 at 3:35 AM, Invidiosulus said:

Typically when a material decreases in thickness...

the Q of the resonance will decrease.

it will be resonating across a broader frequency.