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Alexander

A55g and need for an HF crossover point mod?

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5 minutes ago, Alexander said:

 

I will tell you when I changed out the k52h to the a55g's it was immediately apparent of the change for the better. I would not hesitate to recommend them to any klf-20/30 owners if they could afford them.

I am 62 so I am sure I have lost some hearing too. I use to hear the 17.5Hz from the tripler on CRT TV's, that would drive me nuts.

I'm a few months behind ūüôā¬† I'll have to keep an eye if you post the measurements.

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1 hour ago, pzannucci said:

I use to hear the 17.5Hz from the tripler on CRT TV's, that would drive me nuts.

 

For that reason I could tell if folks were home but just not answering the door when I was there to collect paper route money back in the day.  Now I hear a little something like that at all times, maybe not quite that high...

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2 hours ago, Alexander said:

OK, figured out how to create a transformer in LT Splice and I think we would need to look at it as a step down since we are cutting voltage to the driver. Here is the YouTube video I followed: https://www.youtube.com/watch?v=mzwuJ0y8vuw&t=253s

 

I'm not saying I believe going to all that trouble is a waste of time in every case, but that in a loudspeaker crossover it is.  Please let us know in what way the included model drives any changes to any of the other components.

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2 hours ago, Alexander said:

OK, figured out how to create a transformer in LT Splice and I think we would need to look at it as a step down since we are cutting voltage to the driver. Here is the YouTube video I followed: https://www.youtube.com/watch?v=mzwuJ0y8vuw&t=253s

 

So if I am correct then we need to place values in henrys (mH in our case) and the primary (mH) to secondary windening ratio is squared and that value will be used on the secondary side of the model. If I am right then where can we find the induction values of the primary side? Would we actually measure that?
 
I have measured an unmarked auto transformer that I was told was a t7a (-10db) and here is what I got. 0-5 (primary yes?) is 105.3mH/2.2ohm & 2-5 (secondary yes?) is 49.5mH/.89ohm. I did a third measurement of 0-2 @ 8.2mH/.22ohm but did not think that info is used. Pure DC resistance values were 131.3, 61.4 & 10.6ohms. All measurements were done using DATS v3.

Although the video describes a transformer instead of an autotransformer, it will still work.  If your primary inductance is 105.3 mH, then set your secondary inductance to

10.53 mH.  The 10 db turns ratio is 3.165.  3.165 squared is 10.  Since this a step down transformer, you divide the primary inductance (105.3) by 10 to get the secondary inductance (10.53).  I haven't tried this, but I think I got the math right.

 

If you want to model an autoformer, the inductor values would be 49.2 mH and 10.53 mH.

 

Mike

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13 hours ago, pzannucci said:

Also the KLF does not have an upper crossover cut off on the mid.  It naturally rolls off. 

I hadn't noticed that. Makes things easier. I'd probably leave the auto transformer in its factory setting and if anything, adjust the 22ohm resistor by a few ohms either way if needed. Maybe you'll get away with leaving the mid circuit as is and only slight changes to the tweeter if that.

8 hours ago, Alexander said:

The plan is to do actual measurements with a to-be-ordered calibrated mic via REW and then we will see if there is any need to consider changing anything.

Simple sweep measurement from your sitting position will show anything obvious. 

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10 hours ago, MechEngVic said:

Simple sweep measurement from your sitting position will show anything obvious. 

So in another thread the A55-g was substituted in a Chorus II which has the same stock mid driver as the KLF-30 and measurements were taken. You can see in the graph that output is in fact down a little but not in the area above 6khz:

 

 

experiment.jpg.76a795614c2f05583eaa8496f3451a02.jpg

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3 hours ago, jjptkd said:

So in another thread the A55-g was substituted in a Chorus II which has the same stock mid driver as the KLF-30 and measurements were taken. You can see in the graph that output is in fact down a little but not in the area above 6khz:

 

 

experiment.jpg.76a795614c2f05583eaa8496f3451a02.jpg

The dip in the second graph, green line, starts at the crossover point between the woofer and mid. I wouldn't doubt that entire dip is due to the interaction of woofer and new mid driver. Your setup might respond similarly. The crossover of the Chorus ii is almost identical to the KLF-30 in the mid and tweet, so I bet you don't have any issues at the mid/high point, but will have issues at the woofer/mid handoff like in this graph. It almost seems like the a55 is less sensitive than the k52, at least at the low end. The good thing is you have some breathing room with that 22ohm resistor (you can give the a55 more current by lowering the value, maybe 15ohms), and you can ask the woofers to do a few more Hz by raising the value of the 97mf cap (by adding parallel caps, maybe 3-6uf), those woofers can certainly handle it. None of these changes should mess with your impedance too much either. 

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22 minutes ago, MechEngVic said:

The crossover of the Chorus ii is almost identical to the KLF-30 in the mid and tweet, so I bet you don't have any issues at the mid/high point, but will have issues at the woofer/mid handoff like in this graph. It almost seems like the a55 is less sensitive than the k52, at least at the low end.

 

In the case of my Chorus II's I felt the drop in output in that frequency band actually helped to balance the speaker out for me. At lower volumes the bass sounds more "full" as the mid horn did not overpower the bass as it tends to do at least in my room and also at higher volumes where the stock driver / mid horn can get just flat overbearing and shouty the A55-g maintains it composure quite well and stays smooth.

 

I don't know how the lower output of the driver would sound in the KLF-30 never tried it myself but I thought it worked great in the Chorus II. I initially tried the driver in a forte II and personally found the sound of the mid to be too laid back for my taste as the forte mid is already dialed back quite a bit compared to the Chorus.

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31 minutes ago, MechEngVic said:

 It almost seems like the a55 is less sensitive than the k52, at least at the low end.

I measured roughly a 2-3db drop in output with the A55-g compared to the stock k-61 driver, same as the k-52 slightly different horn.

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Posted (edited)

Wow, this is basically the same thing. Can not believe I did not make the connection between the two back then as I did read that thread. This is exactly what we were wanting to look at and basically try and tweak the xo.

 

Looking at the Chorus II & klf-30 schematics there are virtually identical with the excretion of the LF side due to the different woofer arrangement. The only change is the klf-30 used a 22ohm and not a 20ohm resister. Curios though how much change there might be with the different horns being used.

 

The plan now will be when we order/receive a miniDSP microphone in about a month we will be taking our own measurements so we can compare graphs. I need to get some 82,68 & 47ohm resistors and also have a slew of Solen/Dayton .47-2uF caps to test with and when (if) we settle on a value we can get some matching Audyn plus caps.

 

 

 

note: Yikes! Looks like a few posts showed up bettwen jjptkd and this one

 

 

Edited by Alexander
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7 hours ago, jjptkd said:

 

In the case of my Chorus II's I felt the drop in output in that frequency band actually helped to balance the speaker out for me. At lower volumes the bass sounds more "full" as the mid horn did not overpower the bass as it tends to do at least in my room and also at higher volumes where the stock driver / mid horn can get just flat overbearing and shouty the A55-g maintains it composure quite well and stays smooth.

 

I don't know how the lower output of the driver would sound in the KLF-30 never tried it myself but I thought it worked great in the Chorus II. I initially tried the driver in a forte II and personally found the sound of the mid to be too laid back for my taste as the forte mid is already dialed back quite a bit compared to the Chorus.

exp7b8bfdvc7555.thumb.jpg.77343e44991637439472d4390f919294.jpg

 

The blue circle represents the "hot" part of the mid, that 1500-3000hz hump, it's what give Klipsch horns their beautiful midrange forwardness, that midrange sound that is so addictive and unique compared to other speaker brands. The problem is that hump can be too hot in some setups. But you don't want to eliminate the hump you just want to tame it a bit. This is why I recommend that instead of changing inductor and capacitor values for the horns (for the woofers it's ok), you use resistors. Properly placed resistors can lower the curve without changing its shape.

 

In this graph, the green curve (the blue circled part), the hump has been lowered but the curve between 600 and 1500hz is an issue (the orange circled part). I drew in a black line to illustrate a better position of the curve at that range; while not eliminating the 2k hump, just making it a bit smaller. 

 

If you run into the same issue, and you want to keep the mid where it is, you can add capacitance to the high frequency roll-off of the woofers, allowing them to roll off a bit higher and cover those overly tamed frequencies between 600 and 1500hz. 

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Cool beans! My first thought was to change the tap on the 3636 from -6db to something less, like maybe -3-4db. That is what launched the start of trying to model autotransformers and any collateral changes one may have been needed. Doing the math a 47ohm nets 14.9ohms and 56ohms nets 15.8ohms, I tend to be on the conservative side so we would start with the 56ohm. But first we will have to put the k52h back in and get a baseline when we have a microphone.

 

I would like to thank everyone for all of your time taken with your posts trying to help me understand.

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18 hours ago, Alexander said:

Wow, this is basically the same thing. Can not believe I did not make the connection between the two back then as I did read that thread. This is exactly what we were wanting to look at and basically try and tweak the xo.

 

Looking at the Chorus II & klf-30 schematics there are virtually identical with the excretion of the LF side due to the different woofer arrangement. The only change is the klf-30 used a 22ohm and not a 20ohm resister. Curios though how much change there might be with the different horns being used.

 

The plan now will be when we order/receive a miniDSP microphone in about a month we will be taking our own measurements so we can compare graphs. I need to get some 82,68 & 47ohm resistors and also have a slew of Solen/Dayton .47-2uF caps to test with and when (if) we settle on a value we can get some matching Audyn plus caps.

 

 

 

note: Yikes! Looks like a few posts showed up bettwen jjptkd and this one

 

 

This is why I always say KLFs (Legends) are Heritage though everyone poo-poos the KLFs and my analogy.¬† Since the KLF 20s have really good woofers and KLF 30's woofers are/were used in the Jubilee, to me it makes perfect sense that KLFs were a more room friendly Heritage base.¬†ūüėĎ

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11 hours ago, MechEngVic said:

exp7b8bfdvc7555.thumb.jpg.77343e44991637439472d4390f919294.jpg

 

In this graph, the green curve (the blue circled part), the hump has been lowered but the curve between 600 and 1500hz is an issue (the orange circled part). I drew in a black line to illustrate a better position of the curve at that range; while not eliminating the 2k hump, just making it a bit smaller. 

 

These are not my measurements and honestly I was quite surprised by the large dip myself when I first seen this. When I took measurements it was directly at the horn mouth purposely trying to isolate the mid driver-- I used an SPL meter and ran frequency sweeps several times for each driver and I did not experience any big dip like that in fact the A55-g actually played pretty flat from about 530hz-6300hz IIRC compared to the k-61 at around 620hz-6700hz, the a55-g was 2-3 db lower in output across the board.

 

I guess I should invest in some testing equipment I do enough modifications that it would be interesting to get a visual on what I'm hearing with each change. Been looking at the mini-dsp's as well just not sure if I want to open that big can of worms or not.

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6 hours ago, jjptkd said:

When I took measurements ... I used an SPL meter and ...  did not experience any big dip like that 

 

The notion of using such a device in such a way had never crossed my mind before stumbling upon this (my first audio-related) forum whenever-it-was ago.  Upon encountering it the first time, my immediate thought was wondering just how well-calibrated such a meter might possibly be at various specific frequencies and whether, because of that, it's actually suitable.  Certainly not one that cost less than (and is actually worth) several hundred dollars, I'd guess.  Do they come with documentation indicating their inherent frequency response characteristics?

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18 hours ago, jjptkd said:

 

These are not my measurements and honestly I was quite surprised by the large dip myself when I first seen this. When I took measurements it was directly at the horn mouth purposely trying to isolate the mid driver-- I used an SPL meter and ran frequency sweeps several times for each driver and I did not experience any big dip like that in fact the A55-g actually played pretty flat from about 530hz-6300hz IIRC compared to the k-61 at around 620hz-6700hz, the a55-g was 2-3 db lower in output across the board.

 

I guess I should invest in some testing equipment I do enough modifications that it would be interesting to get a visual on what I'm hearing with each change. Been looking at the mini-dsp's as well just not sure if I want to open that big can of worms or not.

I was aware these were from another post. When you measure the whole speaker at the same time you might see this kind of dip. The dip is not only due to the mid driver itself but the interaction of the mid and woofers. Even a cell phone app will show you if there is a dip or hump big enough to worry about.

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On 3/28/2020 at 12:21 PM, glens said:

 

The notion of using such a device in such a way had never crossed my mind before stumbling upon this (my first audio-related) forum whenever-it-was ago.  Upon encountering it the first time, my immediate thought was wondering just how well-calibrated such a meter might possibly be at various specific frequencies and whether, because of that, it's actually suitable.  Certainly not one that cost less than (and is actually worth) several hundred dollars, I'd guess.  Do they come with documentation indicating their inherent frequency response characteristics?

I think for the purposes I was using the information derived from the test for it was adequate as I was basically just trying to find the differences between the stock driver and the A55-g in that particular application to satisfy curiosity more than anything and to confirm what I thought I was hearing which was slightly lower output of the A55-g, I would certainly want a more precise set of measurements before altering the crossover or making any changes to the speaker. 

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@MechEngVic  Here is my latest graph.  I find this stuff really interesting, but I really don't understand it at all until someone like you breaks it down.  Thank you

My thread can be seen here

 

graph.jpg

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On 3/28/2020 at 7:50 AM, pzannucci said:

This is why I always say KLFs (Legends) are Heritage though everyone poo-poos the KLFs and my analogy.¬† Since the KLF 20s have really good woofers and KLF 30's woofers are/were used in the Jubilee, to me it makes perfect sense that KLFs were a more room friendly Heritage base.¬†ūüėĎ

 

Yep. The KLF line seems to be looked down upon by some ‚Äď even more than the forte's & Chorus's. For many different reasons there are people that just can not have Cornwall or higher model speakers.

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3 minutes ago, Alexander said:

 

Yep. The KLF line seems to be looked down upon by some ‚Äď even more than the forte's & Chorus's. For many different reasons there are people that just can not have Cornwall or higher model speakers.

I will take my KLF-30s over Cornwalls (maybe not IVs though I have not heard them).  I've owned much of the Heritage line (probably 4 different pair of khorns, along with La Scala, Cornwalls, etc. - no Chorus IIs though), outside of Jubilees, and the KLF-30s are still here.  Forte IIs will also likely hang around for a while...  just because...  They are one of the most collectible Klipsch.  So to me, KLF is an excellent choice and a killer rock and roll speaker as one Audio Salesman told me when I was looking at B&W N801s.  You just need to feed them well.

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