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Inherited 6 La Scalas - Need some assistance please


Ed Wolinski

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22 minutes ago, Travis In Austin said:

In that circuit, forgetting the screw for a second, if you put in a 300 rated air core inductor what would you expect to see in the crossover frequency? A rise, a drop. Any way to predict how much change to expect?

I'm not familiar with the particular circuit in question, so I can only answer in generic terms.


From https://www.calsci.com/audio/X-Overs1a.html:

For a first-order crossover, L = R/(2PI*f). Rearranging that, f = R/(2PI*L). 
If L is multiplied by 1.1, an increase of 10%, then f will be divided by 1.1, a decrease of 9.09%.

 

On to the next page, https://www.calsci.com/audio/X-Overs1b.html:

For a second-order crossover, L = R/(2PI*f*Q). Rearranging that, f = R/(2PI*L*Q).
Again, if L is increased by 10%, then f will be decreased by 9.09%.

 

It gets more complicated with higher-order crossovers. I don't know what the order is for the crossover in question.

 

Quote

What are the typical tolerances and these kind of conductors? 1% 5% 10% 20?

 

A quick glance at Parts-Express shows 5% and 1%, priced accordingly.

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4 hours ago, Edgar said:

 

Let me start with the disclaimer that I agree with your statement.

 

That said, here we are on a forum that has seen long discussions about the sonic signatures not only of different capacitor dielectric materials, but of different capacitor manufacturers using the same dielectric materials. In that context, we are now dismissing as "negligible" the measurable distortion, not to mention the change in inductance, resulting from an iron bolt inserted into the magnetic field of an air-core inductor.

 

I just sit back and grin. We audiophiles are an amusing bunch. And please take this comment in the light-hearted nature with which it was written.

 

Splitting frog hairs is what audiophiles do on forums. Technicians that repair audio gear use what they have in stock and think, good enough while doing so. 

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On 1/22/2023 at 8:48 AM, Deang said:

I should have just went to bed last night! Why was I posting about a screw at three in the morning! 

That could have gone sideways really quickly if taken out of context...

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 .

 

this screw question was repeated ad nauseam over the years     Mike Colter ,  who worked for klipsch Technical support  tested both the magnetic and non-magnetic  screws in the klipsch  anechoic chamber .  

 

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I've tested the brass/steel screw theory in Klipsch's anechoic chamber. Acoustically (measureably) it doesn't make a gnat's butt difference what the screw is made of. Electrically, in theory, it might have some effect, but it's immeasurable on a frequency response curve, so it must not affect the values within the crossover network to any great degree.

 

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My inductance meter reads .34mH with ferrous screw. BEC (may he rest in peace) measured .35mH. 
 

A 40% increase in the inductance (.245mH to .34mH) which in turn models a response curve that gives a drop in the K77 crossover point from about 5800Hz to roughly 4800Hz.  Just looking at the numbers, it would be quite reasonable to assume one could hear a difference, even if it is being caused by an unorthodox ferrous core. 


Anyway, to each his own. I truly was just trying to help out. 

P.S. I read the linked thread above. BEC ran some curves and found the ferrous screw flattened the response by cutting the lower end of the response by 4dB (there was a mild peak there). I would like to see the anechoic curves. 

 

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It is VIP  to note that  the non- magnetic screws or the ferrous screws  used in the AA were not  identical across the board   , the bump in inductance varied  typically whether the screw was  brass , ferrous , or   stainless  steel  .

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44 minutes ago, OO1 said:

this screw question was repeated ad nauseam over the years     Mike Colter ,  who worked for klipsch Technical support  tested both the magnetic and non-magnetic  screws

So you made up everything else in your post like they ran out the f brass screws, that it was tested by Klipsch Engineering, every crossover is tested? Or is that just a mistaken assumption on my part based on your choosing not to answer any of the questions?

 

Let me simplify it for you. What’s your basis for saying they ran out of brass screws? Something you read on here? Something you heard from someone? Or was my assumption correct, you are just assuming they ran out of brass because they started using ferrous/steel?

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1 minute ago, OO1 said:

It is VIP  to note that  the non- magnetic screws or the ferrous screws  used in the AA were not  identical across the board   , the bump in inductance varied  typically whether the screw was  brass , ferrous , or   stainless  steel  .

Please, quit while you are ten feet under. Was stainless used by the factory? Has anyone measured the stainless?

 

Stainless is ferrous by the way, meaning it’s made with iron, but is has chromium to significantly reduce corrosion, and nickel, which in sufficient amounts will render the material “non-magnetic” I.e. it won’t be attracted to a typical magnet. 

 

 

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26 minutes ago, Travis In Austin said:

 

Please, quit while you are ten feet under. Was stainless used by the factory? Has anyone measured the stainless?

 

Stainless is ferrous by the way, meaning it’s made with iron, but is has chromium to significantly reduce corrosion, and nickel, which in sufficient amounts will render the material “non-magnetic” I.e. it won’t be attracted to a typical magnet. 

 

 

 Lol ,  Stainless steel can be  magnetic or non-magnetic depending if the steel at it's core is  ferro-magnetic or not  .  

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2 hours ago, Travis In Austin said:

I guess I really even need to learn something more basic. Does the air core inductor, in that circuit relate to what the XO frequency will be. (If so, is that because it is acting as a low pass filter, only allowing frequencies abound a certain number, pass to the tweeter). Or maybe It’s doing none of these, or all of them.

 

 

The shunt inductor on the AA tweeter circuit controls the amount of current passing through the driver.  It's impedance increases with frequency.   It's really acting like a high pass filter.

 

As frequency decreases, more current will pass through the shunt inductor, and less current will pass through the driver. 

 

As frequency increases, less current will pass through the shunt inductor, and more current will pass through the driver.

 

The larger the inductor, the sooner in frequency the current across the driver will peak.

 

2 hours ago, Travis In Austin said:

Is there a corresponding high pass filter in the Squawker XO circuit?  

 

 

Yes...it's the T2A autoformer, which is a 21.2mh inductor across the squawker.

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20 minutes ago, OO1 said:

 Lol ,  Stainless steel can be  magnetic or non-magnetic depending if the steel at it's core is  ferro-magnetic or not  .  

Stay out of this thread, do not post in here again. 

 

I and others said exactly that 20 posts ago. Since you are quite adept at googling stuff as you go along, take the time, instead of posting in this thread, to research what austenitic stainless steel is. You are spinning in circles and not taking the time to read and understand what others are saying and talking past people who are seriously trying to figure out something and learn. This is called listening and you need to start doing that, it's just good plain forum etiquette. 

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1 hour ago, Klipschguy said:

A 40% increase in the inductance (.245mH to .34mH) which in turn models a response curve that gives a drop in the K77 crossover point from about 5800Hz to roughly 4800Hz.  Just looking at the numbers, it would be quite reasonable to assume one could hear a difference, even if it is being caused by an unorthodox ferrous core. 

1 hour ago, Klipschguy said:

Anyway, to each his own. I truly was just trying to help out. 

You are helping, significantly. 

This is what Bob Crites (may he rest in peace) said he got (from the thread quoted up above by OO1 regarding Michael Colter's post):

 


"Michael,

The steel screw changes the 245 uH inductor specified on the schematic to about a 350 uH inductor. So, the question would be, is 245 uH right for the inductor in the tweeter circuit or is 350 uH right? Anyway, pretty simple to replace the screw with one that is non-magnetic making the crossover match the schematic"

 

First, I have been lax in specifying the units with microhenrys (mH) or ultrahenrys (uH). Bob measured 350 ultrahenrys (uH) which is .35 mH, correct? You measured .34 mH (340 uH). Just want to be sure I'm correct in apples to apples here despite some using uH numbers, and mH numbers. You got also exactly what Bob got?

 

I will have to go back and read Michael's thread and find where Bob indicated that it was a 4dB change and to also see if he discussed a change in the XO frequency. I would assume it did and that accounts for the 4dB change based on the slope. 

 

A simple frequency response curve would show a 4dB "dip" in that area correct? 

40 minutes ago, mboxler said:

It's really acting like a high pass filter.

I always reverse these, just the way my brain works. Last thing I wanted was to add to the confusion. A low pass filter is what subs have (passes frequencies lower than a specified cut off frequency and attenuates frequencies above the cut-off frequency). So yes, what I  meant was a high pass filter: because for a tweeter, you want to allow signal above a specified frequency cutoff and attenuate frequencies below that cut off.

 

@Deang we were witnesses to a discussion between Bob and Roy about this issue in September of 2006, do you remember? I do?

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27 minutes ago, Travis In Austin said:

First, I have been lax in specifying the units with microhenrys (mH) or ultrahenrys (uH).

Just a point of correction:

 

mH is milliHenry; 1/1,000 Henry.

 

uH (more correctly µH) is microHenry; 1/1,000,000 (one millionth) Henry.

 

1 Henry is a really big inductor.

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41 minutes ago, Edgar said:

Just a point of correction:

 

mH is milliHenry; 1/1,000 Henry.

 

uH (more correctly µH) is microHenry; 1/1,000,000 (one millionth) Henry.

 

1 Henry is a really big inductor.

Oh my gosh, where did I get "ultra". Now I have to edit, I really hate with that happens. 

 

It's math, I don't do math. But a milliHenry is 1/1000 or a microHenry right? 

 

Who knows Mr. Henry's other great achievement besides discovering electromagnetic induction (hint, it's related to history and learning). Where does his portrait hang in Washington, D.C.?

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2 minutes ago, Edgar said:

No, it's the other way around. A microHenry is 1/1000 of a milliHenry.

Why don't Bob's curve and Klipschguy's curve look more the same? Or are they the same but look different because of the scales?

 

Bob's shows the Red curve to have a 3 to 4dB bump up at an almost identical point as the blue, the blue is flatter and doesn't have the bump up (I can't figure out what frequency that is happening at from the scale on the bottom "0 to 25.6 kHz). 

 

Klipschguy there are almost two identical curves, with one shifted slightly left/right of the other one. 

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