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Crossover options for Klipschorns


psg

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Now that our Canadian dollar is (almost) at par, I'm thinking of trying after-market crossovers in my 1978 Klipschorns (with Bob Crites tweeters).

I'm keen on perhaps trying the ALK Engineering Universal in kit form ($290), but should know about other options. A while back people were gtalking about the "ALK Jr.". What is it in relation to the Universal? Who makes it? Also I remember reading a suggested crossover frequency mod that is beneficial to users of the Bob Crites tweeter? Do that apply to either of those networks?

Any recommendations out there?

Thanks!

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Peter, you have a number of options. First, you might want to read this recent thread:

http://forums.klipsch.com/forums/1/962682/ShowThread.aspx

In that thread, you will find opinions ranging from spend $50 and get some new caps to go for Al's best stuff (esns). I also posted links to a number of past threads on crossovers.

I've run Klipsch OEMs, freshened As, AAs, ALK, Srs., and now Al's Extreme Slope tops and gentle slope bottoms (APT12-350 bottom, ES5800 top). I ended up preferring Al's extreme slope tops with the gentle slope bottoms (with OEM K55 drivers) for my Klipschorns in the front, but I still really like the ALK Srs. in my Belles (in the rear). In fact, so much that since I'm installing new midrange drivers tonight (JBL 2470s), I'm going to try the ALK Srs. with them.

To my recollection, ALK, Jrs. is a constant impedence design created by Al Klappenberger and Dean built them with permission. I think that they are very similar to the ALK Srs (the "Universal"), with the exception being that there is a gentler slope crossover on the tweeter. The suggested frequency mod benefitting users of the Crites tweeter is not applicable to the ALK Srs. or Jrs. (although Al maybe could do that), but is commonly done with Crites rebuilt A crossovers.

Both A and AA clones, patterned after the Klipsch design, are great simple crossovers but they start to pinch at medium to higher volumes. The ALK Universals and Jrs. employ steeper slopes on the squawker/tweeter crossover and to my ears, sounded better both with respect to bass performance and on the upper end at higher volumes. Al's Extreme Slope networks sound clean and clear all the way up in the volume (at somewhat of a sacrifice in a less full sound at lower volumes), but of course, they are more complex and more expensive. As a volume junkie, I love ES networks. That being said, I may like the ALK universals at higher volumes as well, now that I've upped the ante with respect to the mid driver.

In summary, I highly recommend ALK Universals. With stock Klipsch drivers, you should love them unless you really like laying into the volume levels.

Of course, only my opinion - others may differ.

Carl.

BTW, nice call on the Crites tweeters. I love the Eminence tweeter drivers (what Bob uses in his tweets), and I actually prefer them to the Beymas. I may end up keeping the Eminence in the Khorns instead of going to JBL 2404s. I even recently replaced the tweeters in my Fortes with Eminence drivers. Now, I have all Eminence in my front five.

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Thanks Carl! I really appreciate your thorough answer! I had already recapped my AAs after purchasing the speakers used, and that had made a huge difference. Those rebuilt AA crossovers won't go to waste because they will cascade to my older-still (and never recapped) La Scala.

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You said that you had refreshed the caps on the crossover and liked the improvement. What is it about the current set up that you do not like?

The prices that are being discussed could put you within reach of a very different strategy. However, this strategy has some significant caveats.

If you are using a digital source and if you are not committed to limiting yourself to very expensive amplifiers, I would suggest that you consider using an active crossover (digital). One possibility is an EV dx38 (for about $2500 new) or a Behringer DCX (for about 1/10 the price) and get a second (or third) amp. Now you will be in the position to 1) employ steepish crossovers (which can provide a number of benefits) 2) time align the bass bin to the mid-range and 3) get the advantages of bi-amping (or tri-amping) which can increase the headroom (the amplifiers are now only working on a portion of the bandwidth). I believe that #2 can be fairly important and #3 can be important if you are using smallish amps, and #1 can help in a number of ways (which I will not attempt to quickly discuss). My opinion is that these benefits will outweigh the possible benefits provided by some of the other suggestions. However, I think you have already made a significant gain by merely refreshing the caps.

The caveat of using a digital source is based on my experience in setting up circuits and helping others do the same. If you do not have a digital source, then another A-to-D conversion is involved and there a number of ways to screw this up (many folks will "get it wrong") although with sigma delta modulation, the problems are not as severe as in the old days. Another caveat is that using this strategy will require a volume control after electronic crossover. Fortunately SFOGG has outlined the above issues nicely in setting up such a circuit and a trick for making the crossover slopes very sharp. Before going this route, read his posts carefully and draw out your plan.

If you need to use an analog source, this may not be a good path since a lack of familiarity with ADC & DAC issues could lead to a situation where things could actually become worse. Please take this last concern seriously.

Good Luck,

-Tom

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Ditto what Tom said.

I might only add that one doesn't necessarily need to be familiar with ADC/DAC issues in order to optimize their performance. There is definitely a learning curve involved with active crossovers, but I'm convinced they're the only way to go...

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Peter,

I am replacing the top sections of my Khorns with Altec 311-90/290-16K and JBL 2404H. I am also looking into using digital crossovers. I was planning to use my SETH 2A3 amps for the mid sections but I came across this post from shawn that made me think twice before goig ahead with digital crossovers. I have tube preamps and tube amps that I like to continue using and they don't seem to integrate well with digital crossovers. YMMV.

Kudret

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One heads up on the Dx-38, it's two in and four out. I presume it would force you to have SOME kind of passive on the top end and you would only use the DX to split the woofer out. Works great for biamping a 2-way but for a 3 way I think you'd have other issues to solve (and they'd probably be easy to solve??)

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One heads up on the Dx-38, it's two in and four out. I presume it would force you to have SOME kind of passive on the top end and you would only use the DX to split the woofer out. Works great for biamping a 2-way but for a 3 way I think you'd have other issues to solve (and they'd probably be easy to solve??)

Biamping 2-way looks like a good compromise to me. Is it possible to eliminate the woofer inductor on Type A/AA and use the rest for the tweeter and squawker?

Kudret

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Actually, I just remembered djk posting this a while back....

You COULD use a Dx38 with the Khorns. What you do is send a full range signal to the bass amp and leave the LF section of the crossover in the khorn. You also run a full range signal to the Dx38 which then feeds the MF and HF amps which can both be delayed to line up with the bass bin. I might need to draw a picture to make this more clear...

post-10350-13819348555274_thumb.gif

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Re: Steepish slopes on the crossovers

When I was messing around with this before (and messing is the right word, nothing was systematic and careful), I noticed an interesting problem. If you are using crossovers that are 1st or even third order (6 or 18 dB per octave slopes) when the gain at the individual drivers is off by 1 or 2 dB the sound is still tolerable (this can be mismatched because of different sensitivities of the driver or the individual amps and this has not been properly compensated for).

However, if the gain is off 1 or 2 dB at the individual drivers with steep crossovers, the discrepancy is quite noticeable and not at all tolerable.

I suspect others have run into this problem also. The consequence is that you really do need to be extra careful about properly adjusting the relative levels when you bi-amp and use steep crossover slopes.

-Tom

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DrWho, This is what I had in mind

.EVDx38.jpg

Does this make sense? I want to use my DIY SETH amps to power the Tweeter/Squawker and I don't want to risk damaging the drivers when powering the amp on. This also eliminates one amp from the equation and all I need to do is buy an SS amp for the woofer. Another problem I have is, due to my tube preamp I will have too many digital/analog analog/digital conversions.

Another benefit of this approach is that it will enable time alignment between woofer and top section, which is more crucial than time alignment between tweeter and squawker, no?

Kudret

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Actually, I just remembered djk posting this a while back....

You COULD use a Dx38 with the Khorns. What you do is send a full range signal to the bass amp and leave the LF section of the crossover in the khorn. You also run a full range signal to the Dx38 which then feeds the MF and HF amps which can both be delayed to line up with the bass bin. I might need to draw a picture to make this more clear...

Under the above configuration, the Dx38 provides your crossover point at the high end of the squawker/low end of the tweeter (5000-6000 or so), but what provides the high pass crossover for the bottom end of the squawker (400hz or so)?

Carl.

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Actually, I just remembered djk posting this a while back....

You COULD use a Dx38 with the Khorns. What you do is send a full range signal to the bass amp and leave the LF section of the crossover in the khorn. You also run a full range signal to the Dx38 which then feeds the MF and HF amps which can both be delayed to line up with the bass bin. I might need to draw a picture to make this more clear...

Under the above configuration, the Dx38 provides your crossover point at the high end of the squawker/low end of the tweeter (5000-6000 or so), but what provides the high pass crossover for the bottom end of the squawker (400hz or so)?

Carl.

The EV Dx38 can also be configured to provide the high pass for the bottom end of the squawker (which is why it's so cool). There is a seperate high pass and low pass crossover for every channel. There is also the option of yet another high pass or low pass crossover for every filter bank too.

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DrWho, This is what I had in mind

.EVDx38.jpg

Does this make sense? I want to use my DIY SETH amps to power the Tweeter/Squawker and I don't want to risk damaging the drivers when powering the amp on. This also eliminates one amp from the equation and all I need to do is buy an SS amp for the woofer. Another problem I have is, due to my tube preamp I will have too many digital/analog analog/digital conversions.

Another benefit of this approach is that it will enable time alignment between woofer and top section, which is more crucial than time alignment between tweeter and squawker, no?

Kudret

Did you intentionally put the passive lowpass in there for the woofer?

I understand your thinking in this approach, but I believe you will notice just as much improvement by aligning the tweeter to the squawker as you would aligning the bass bin to the squawker. I'm not sure which I would consider a higher priority since both crossover frequencies are in rather critical frequency ranges.

As far as protecting your tweeter/squawker - there are two things you can do. First, the easiest approach would be to put a cap in series with the drivers. Second, you can put a soft start protection relay on the output. So basically, the relay is open during power up and power down, and only conducts when the amp is stablized. I would probably do both.

Before we get too crazy into this, I might suggest updating the khorn MF/HF section into a single HF section and turn the khorn into a 2-way like PWK originally envisioned. A K402 should work very well in this regard, but if you were looking for something to drop in and not change the aesthetics, I bet you could get the K510 to work. A K510 should cost about the same as another pair of amps, but is going to sound much better than the original components. I am familiar with all the previous literature talking about the differences of 2-way and 3-way, but these new horns from Klipsch are providing all the benefits of both 2-way and 3-way...simply amazing really. I only bring it up because the price of properly going 3-way is going to be about the same.

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Did you intentionally put the passive lowpass in there for the woofer?

Ooops, I just corrected it.

Before we get too crazy into this, I might suggest updating the khorn
MF/HF section into a single HF section and turn the khorn into a 2-way
like PWK originally envisioned.

It's too late for me. I've got some Altec 311-90 with 290-16K drivers and JBL 2404H.

Kudret

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Guys,

I am not familiar with the EV dx38.

Does it accept a digital input?

Does it have DACs?

Does it have a "master volume control"? (if so, where in the sequence does it work?)

The configuration you have shown has preamp BEFORE the crossover. The EV will be performing an A to D conversion. The signal you will be giving the EV may not be "hot enough" and you may run into a real problem with quantization noise. This will be especially true if the EV is expecting a pro level (8-10volts) rather than a home level (line level or about a volt). I was very careful in a prior post about the issue trying to avoid the extra A-to-D and D-to-A conversions. Many folks will screw this up and get a terrible SNR. If you can put a pre-amp(s) AFTER the EV (there are a number of issues that I previously mentioned), then you are more likely to get a cleaner signal.

Avoid extra conversions, they are prone to introducing noise unless you maximize the bits. If you do not understand this last statement, then you need to familiarize yourself with the use of ADCs and DACs.

Good Luck,

-Tom

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