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La Scala Woes


Desert Noises

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On 12/20/2021 at 11:05 AM, mboxler said:

As you can see, an 80uf capacitor creates an underdamped filter...the voltage across the K33 actually rises around 1.6db before falling.

 

Another reason to use an electrolytic capacitor for this application.

 

Go back into your simulation and add typical series resistance from an electrolytic capacitor, 2-5 ohms and you will see that 355Hz resonance flatten out with the 80uF capacitor.

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25 minutes ago, captainbeefheart said:

 

Another reason to use an electrolytic capacitor for this application.

 

Go back into your simulation and add typical series resistance from an electrolytic capacitor, 2-5 ohms and you will see that 355Hz resonance flatten out with the 80uF capacitor.

 

2-5 ohms?  At what frequency?  My 80uf electrolytic measures .08 ohm ESR @ 1khz.  A capacitor with 2 - 5 ohms ESR would definitely change the frequency response. 

 

Mike

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34 minutes ago, mboxler said:

 

2-5 ohms?  At what frequency?  My 80uf electrolytic measures .08 ohm ESR @ 1khz.  A capacitor with 2 - 5 ohms ESR would definitely change the frequency response. 

 

Mike

 

The resonance should be ~355Hz so measre ESR around there.

 

Typical datasheet for general purpose electrolyics state 2 ohms for ESR at 100Hz, they test at low frequencies because full wave rectification is 100Hz/120Hz.

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FWIW

 

ESR = Xc * tan

 

If you are observant you will notice companies like Rubycon or NIchicon will not say ESR but will only give the loss angle which is .2-.25  throughout any voltage rating or capacitance value (Rubycon datasheet). As you see in the Illinois that ESR is all over the place because it depends on Xc or reactance so the capacitance value dictates ESR, the lower the capacitance value for a given frequency the higher the ESR will be.

 

For the Illinois capacitor we can figure out the loss angle easily by:

 

3.97 / Xc

 

Xc = 13.26 for a 100uF capacitor at 120Hz

 

3.97 / 13.26 = .299

 

So the tan or loss angle is .299 for this line of capacitors.

 

You can figure an 80uF capacitor at 355Hz with a loss angle of .299 will have an ESR of;

 

5.6 * .299 = 1.67 ohms

 

Close to my 2 ohm guess before. Some cheap caps have a higher loss angle and so ESR can be as high as 5 ohms or higher depending.

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I don't know what to say. 

 

My 80uf cap, at 100hz, measures 81.27uf and .017 DF.

81.27 at 100hz = 19.57 ohms.

19.57 * .017 = .33269 ohm ESR.

 

At 1000hz, measures 78.80uf and .037 DF.

78.80 at 1000hz = 2.02 ohms.

2.02 * .037 = .07474 ohm ESR.

 

This is on a DE-500 LCR meter.  May try to find manufacturer's datasheet.

 

 

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12 hours ago, mboxler said:

I don't know what to say. 

 

My 80uf cap, at 100hz, measures 81.27uf and .017 DF.

81.27 at 100hz = 19.57 ohms.

19.57 * .017 = .33269 ohm ESR.

 

At 1000hz, measures 78.80uf and .037 DF.

78.80 at 1000hz = 2.02 ohms.

2.02 * .037 = .07474 ohm ESR.

 

This is on a DE-500 LCR meter.  May try to find manufacturer's datasheet.

 

 

 

Dissipation factor or I was calling tan (tangent, loss angle) same thing is only .017 on your 80uF electrolytic capacitor? Wow that's a really high quality lytic!!! What brand and line of cap is this I wouldn't mind taking a peek at the datasheet too.

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On 12/24/2021 at 4:28 AM, Tom05 said:

(Boxy/ stuffy). Lascala’s shouldn’t sound that way at all . I would turn off your subwoofer run your LS full range and see if it disappears . When running a subwoofer close to your mains you will get a coupling effect around the crossover frequency. If this is your problem move the subwoofer to the rear corner.

 

Depending on the size and layout of your room, having a sub in the back of the room, possibly as well as having one on the front of the room, can run into an unexpected issue.

 

My Yamaha AVR has two Subwoofer sockets, marked Front and Rear.  Therefore, when I got the second sub, it seemed logical to place it at the back of the room.  In order to avoid having its output going into the back of the sofa, I placed it on a barstool-height chair.

 

Makes total sense, right?  Not quite.  I noticed the rear sub would be late to turn on after it sensed bass content.  When I checked, I found that after the front sub turned on, I had to increase the main volume by 6 dB to get the rear sub to turn on.  The ~50-foot-long Audioquest Black Lab interconnect ($170CAD) to the rear sub measured 1 ohm of resistance, while the 6 foot/2 metre Electrohome interconnect measured 0.5 ohm.  This was enough to create this noticeable difference.  At the lower volume levels that I mostly listen at, the rear sub would be turning on and off as the bass content of the music varied, while the front sub would switch on and stay on.

 

With subwoofers, it can be hard to judge tonal differences between two of them, especially to a non-musician (my father, who played upright bass many years ago, told me that with the bass, most people have no clue as to whether or not he’s playing in tune.  He would be in tune, of course, he was just pointing out that at low frequencies the human ear/brain system is operating below the range at which small differences are obvious to most listeners.).

 

So the arrangement might have been great or so-so, but it seemed okay to me.  However, I was pretty dubious at that point, so I relocated the second/rear sub to a position inboard of the Right Main speaker (the left sub is just inboard of the Left Main speaker) and used an old 6-foot/2 metre stereo interconnect, leaving the unused ends hanging.  Both Sub Outs are mono, not stereo, on that AVR, so that was a non-issue.

 

The result:  great sound, a bit of a wall of sound effect (not in caps, because it wasn’t the Phil Spector effect), and both subs turn on and off at the same time.  The system seems pretty synergistic at this point, as indicated by the fact that for the first time in seventeen years, I have spent a calendar year (2021) without spending anything on the stereo.  Its performance has reached a plateau of enjoyment that allows me to listen without any thoughts of possible/needed upgrades/tweaks creeping into my mind, so now it’s all about the music, as it always should have been.

 

Okay, that was a lot longer than necessary, but it gives a bit of added context, so I have no regrets.  To the OP, good luck on your quest for satisfying sound!

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15 hours ago, Islander said:

 The system seems pretty synergistic at this point, as indicated by the fact that for the first time in seventeen years, I have spent a calendar year (2021) without spending anything on the stereo.  Its performance has reached a plateau of enjoyment that allows me to listen without any thoughts of possible/needed upgrades/tweaks creeping into my mind, so now it’s all about the music, as it always should have been.

 

You know it's good when you are to the point where all you have to do is dust off your system.

 

My wife is working until 10 tonight, so I have been trying to get some wires hidden and things cleaned up and put away.

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  • 4 weeks later...

Alright, I’ve been screwing around some more. Not completely satisfied with my modifications (although they helped) I decided to build my own AL-3 crossovers to get back to the original intent of these speakers. Unfortunately, I threw the original AL crossovers in the trash without first listening to them. I was going to just buy a pair of AL-3, but they are over $700 now! I successfully built a pair of AL-3s (omitting tweeter protection) and I’m pleased with how they turned out. After all that wiring and soldering, I have blisters on my fingers! Now I know why they cost what they do.

 

I returned my La Scalas to bone stock; K-33E, K-55M, and K-77M. For the past week I’ve been critically listening to this configuration with the AL-3 crossovers. After all, this is what I’m going to stick with. Something in the AL-3 got rid of that annoying nasal/boxy/stuffy sound in the bass. Is it the 4mH inductor or the two paralleled 68uF capacitors that are responsible? Aside from that, I just prefer the sound of the good ol K-77 over the CT-120. They just have that top end sparkle. I’m feeling satisfied and my itches are being scratched in the right places.
 

So, here I am having gone full circle with upgrades and changes. Back to original, and that’s what is best for me with the La Scala. All of the upgrade parts now live in my Clonewalls (1526C cast frame, A55G, and CT-120). Oddly enough, my Clonewalls sound about the same as they did before, except for the tweeters. I want to put some K-77s back in there. The top end sparkle is now subdued. Anyone have a good pair of K-77s for sale?

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I literally just gasped out loud when I read that you threw your ALs in the trash, lol.

 

That’s what the Garage Sale section and eBay is for. Posterity at the very least. Plus all that junk about another man’s trash...

 

Glad to “hear” you like the results though.

 

The AL-3 was in the first pair of LaScalas to cross my doorstep and even though I had bought A/4500s and CT-120s in anticipation of using them,  I never felt the need to even try them until several years later in different pair.

 

 

 

 

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32 minutes ago, geoff. said:

I literally just gasped out loud when I read that you threw your ALs in the trash, lol.

 

 

 

 

 

 

That was a few years ago and I regret doing it now. The sentiment then was unanimous that the AL was no good at all. I regret at least not listening to them to get an idea of how they originally sounded. I think the AL-3 gives me that with whatever improvements. 

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@Desert Noises, that sentiment was precisely why I had bought new networks and tweeters prior to even owning a pair of LS.

 

I don’t regret buying the A/4500s, it is a different sound though. Not a better or worse comparison, just preference.

 

But if chucking out the ALs is the worst decision you’ve ever made I publicly applaud your good fortune.

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1 hour ago, Desert Noises said:

Unfortunately, I threw the original AL crossovers in the trash without first listening to them.

 

After all that wiring and soldering, I have blisters on my fingers! Now I know why they cost what they do.

 

 

Don't throw away your ALs.  Even if you don't use them, there are parts in there you can use to build other crossovers. 

 

I am in the middle of building a bunch of crossovers for the first time in many years and yes, this takes quite a bit of time if you want everything laid out nice and neatly.  

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9 minutes ago, Curious_George said:

 

For all their supposed imperfections and limitations (like a SE amp), I love the sound of the K77's I have heard and own. 

Right? I’ve seen the plots on the graphs comparing the different kinds of “better” tweeters to the K77. On paper, the other options look better and have a more consistent response all the way out to 20kHz. That’s valid and respectable. However, our ears are ultimately the final judge. There must be a good reason why Klipsch chose the T35 for decades.

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5 hours ago, Desert Noises said:

Alright, I’ve been screwing around some more. Not completely satisfied with my modifications (although they helped) I decided to build my own AL-3 crossovers to get back to the original intent of these speakers. Unfortunately, I threw the original AL crossovers in the trash without first listening to them. I was going to just buy a pair of AL-3, but they are over $700 now! I successfully built a pair of AL-3s (omitting tweeter protection) and I’m pleased with how they turned out. After all that wiring and soldering, I have blisters on my fingers! Now I know why they cost what they do.

 

I returned my La Scalas to bone stock; K-33E, K-55M, and K-77M. For the past week I’ve been critically listening to this configuration with the AL-3 crossovers. After all, this is what I’m going to stick with. Something in the AL-3 got rid of that annoying nasal/boxy/stuffy sound in the bass. Is it the 4mH inductor or the two paralleled 68uF capacitors that are responsible? Aside from that, I just prefer the sound of the good ol K-77 over the CT-120. They just have that top end sparkle. I’m feeling satisfied and my itches are being scratched in the right places.
 

So, here I am having gone full circle with upgrades and changes. Back to original, and that’s what is best for me with the La Scala. All of the upgrade parts now live in my Clonewalls (1526C cast frame, A55G, and CT-120). Oddly enough, my Clonewalls sound about the same as they did before, except for the tweeters. I want to put some K-77s back in there. The top end sparkle is now subdued. Anyone have a good pair of K-77s for sale?

I'll trade you a pair of K77 for your CT-120's

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20 minutes ago, Desert Noises said:

I have a pair of CT-125s that I’d be willing to trade for a pair of K77s.

Fairly lateral move in my opinion. Not worth the effort or shipping.

I much prefer the 120 (in my little mind). That would make it worthwhile to me.

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