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Modifying AA crossover to cross at 4500hz


geoff.
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4 minutes ago, geoff. said:

@Dave MacKay, one thing I have seen many users comment on in this forum is that the cheaper ones often fall short of expectations.

 

Which stands to reason.

 

From what I have read the Xilica XP-4080 is the end game here. I think it is what is used in the latest Jubilee.

There is no doubt that the Xilica XP is a good unit (although it does not have digital inputs, which some of us prefer). What is not being mentioned is the "cost to play". The Xilica unit does not come on the used market very often and the new ones cost close to a thousand. 

 

There are options and much of it depends on your signal chain (is the attenuation before or after the DSP box, are you using vinyl, and will you be feeding the box a digital signal ....).

 

Good luck,

-Tom 

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BTW, The issue of whether to go for DSP (and bi-amping, room correction etc) is a worthy topic but substantially different than the current discussion on modifying some of the standard analog Klipsch crossovers. 

 

Perhaps a new thread is in order or reviving some of the previous threads that were more on-topic. There is already a ton of good information that has been posted. Chris was a frequent contributor and did a good job in laying out the major issues. 

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A little off topic, but...

 

I have designed, but not built or tested, a crossover loosely based on Al's Universal, so we'll call it the Universal 4500.  The new components not only change the electrical cross between the mid driver and tweeter to 4500hz, but also allow you to change the attenuations of either/both of them.  This was accomplished by the combination of the familiar "swamping" resistor, and the moving/modification of the mid driver low pass components to the output side of the autoformer.  Since this is just a third order to the tweeter, I'm not sure it's steep enough for a K77 at that lower crossover point. 

 

No idea how it would sound, but would be an interesting experiment! 

 

Mike 

 

 

 

  

Screenshot (81).png

Screenshot (79).png

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2 hours ago, mboxler said:

Since this is just a third order to the tweeter, I'm not sure it's steep enough for a K77 at that lower crossover point.


Technically, the K77 (AKA EVT35) can be crossed over as low as 3500Hz according to EV data. The question is how does it sound being crossed over that low. 
 

At low to moderate levels, it is probably OK, but at higher levels it probably sounds better crossed over higher. 
 

Your crossover looks interesting. Are you going to build it and see how it sounds?

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On 12/10/2021 at 10:25 PM, Deang said:

General impressions?

Deang, I built the universal 4500 xover some time before 2017 after replacing the K77 with a DE120. At the time I thought it sounded clearer, it certainly measured better. I subsequently built an ES400/ES4500 that I posted about on Stereonet after seeing a post by ALK who was banned from the Klipsch forums at that time.

https://www.stereonet.com/forums/topic/118361-k-horn-crossovers-from-ak-3-to-universal-to-es/?_fromLogin=1 ALK was supportive and offered a few modifications.

 

Since then I have gone active with a miniDSP 2X4HD for each K-Horn doing xover, EQ, time alignment and phase correction. Cost a lot less than building the ES networks and sounds really good.

 

I am now way off topic.

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@Wirrunna, your experience and perspective is greatly appreciated. And thank you for the link! 

 

I believe active is where it’s at, even though I have not gone there yet.

 

And your point about your solution being less expensive than a set of ES crossovers is entirely on point.

 

If I were new to this hobby I would not hesitate to jump head first into the digital solution. 

 

 

 

 

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On 12/4/2021 at 4:27 PM, Curious_George said:

The "A" crossover is one capacitor, 6dB/octave.

 

The "AA" crossover is two caps & coil, 18dB/octave + back to back Zener diodes for "more" tweeter protection. 

 

More like 21 dB/Oct because of the built in EQ.

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On 12/4/2021 at 12:32 PM, geoff. said:

Was just reading another post and noticed @Dave MacKay asking a question that has crossed (no pun intended) my mind more than a few times now.

 

EVERYTHING Klipsch now designs crosses lower to the tweeter.

 

The latest La Scalas have crossed at 4500hz for two generations now.

 

Since the AA seems to hold it’s own amongst the competition how would it be modified to cross at 4500hz?

 

Has anyone tried this? 

 

And if so how were the results?

 

 

 

You could do it, but dropping the xover point to 4500 Hz and keeping the 6k - 9k EQ on the K-77-? will be tough.  At 105 to 106 dB, the K-77s are a little hot, too.  I believe you would need to double the attenuation of the Type AAs 21 dB/Oct to protect the tweeter. 

 

The literature indicates the lower crossover point results in nearly equal horizontal dispersion between the squawker horn and the K-77 at that crossover point. 

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7 hours ago, JohnA said:

The literature indicates the lower crossover point results in nearly equal horizontal dispersion between the squawker horn and the K-77 at that crossover point. 

 

It was only a few years ago that I realized that speaker designers would do that for their direct radiator designs. Crossover points were matched with the polars of the separate components for more even coverage at all frequencies.

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7 hours ago, JohnA said:

 

You could do it, but dropping the xover point to 4500 Hz and keeping the 6k - 9k EQ on the K-77-? will be tough. 

 

I couldn't find an LTspice simulation of the AK-4, so here's what I came up with.  The AK-4 high pass to the tweeter in green and the AA in red.  If I did it correctly, seems as though EQ is reversed between the two in that frequency range(?).

 

Mike

 

 

 

Screenshot (83).png

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Look at the plot I recently posted showing the K-77-M and K-77-F. These tweeters are not the same.

 

We need to remember too that even if you're using the Universal, lowering that crossover point isn't going to be that healthy for the K-77. So, this should maybe always be in the context of the de10, de120, etc.

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