Heritage crossover history

[jwc]

Damn I missed this thread.

Dean. I have hooked the K55 up to a B-3. What is it that you need to know. I thought it sounded good.

Al. When you say the B-3 crossed the K55 too high, you mean higher than 600Hz right? I was wondering how that 5uF cap got in there. I could never calculate that for 600Hz and second order. What is the relative impedance of the K55 on tap 3...something between 52 and 74.5. I get mixed responses on what it is. I hear the K55 is 13 ohms sometimes and other times I hear 16 ohms. So then when I multiply the impedance by 2 or 4 or whatever due to the autoformer, I get very different results depending on wht the impedance started out with in the first place.

Help here.

jc

[BEC]

jc,

I did some impedance measurements on a K-55V and a K-55M some time back. Results are in this word doc.

Edit: Seems the new forum will not allow a .doc file. I shall convert it to a PDF and try that.

Bob Crites

k-55mimp.pdf

[jwc]

Hey Bob. I have the one you "tested" if that is what you are referring to. You found the K55v to be 74.5 ohms on tap 3. Now if I use that impedence to calculate a second order highpass crossed at 600Hz, I don't get 5uF as the capacitance.

I also see how Klipsch cut big costs by using the 2.5mH inductor for the B-3. They probably had tons laying around from their history of using that SAME inductor for ALL their first order networks. If they were to use the value needed to run in parallel off tap 3, it would have been way more expensive.

Someone mentioned the ability to tolerate louder volumes with the B-3. I have tried this and it is true. The tweeter doesn't start to scream at you. It actually sounds better at louder voulmes. The midrange was somewhat recessed at low volumes. The bass was good.

[Deang]

Dean,

WAA.. waa!

I hated building them too. That's why I dumped them on you. I'll be you thought I was doing you a favor!

Al K

Al, lol, yeah -- I lovingly refer to them as effingALKS while I'm building them.

So, the B3 tweeter is down 2.2dB at 7000Hz -- and this is a bad thing? There is a reported resonance with the B2 tweeter that drives some people up the wall, sort of like a fingernails on the chalkboard effect. Some have mentioned in the past that they think it's around 6kHz. That circuit is 2uF with .25mH back to common. I had thought maybe the change from .25 to .13 in the B3 was made to remedy this.

JC, Where did 75 ohms come from? The highest point in Bob's .pdf as it relates to the Cornwall is at 2500Hz with 13.9 ohms. If you calculate at 65 ohms using a Chebychev alignment with a crossover of 550Hz you get 4.47uF and 2.32mH. Remember that when you horn load a driver it changes the impedance characteristics.

[Al Klappenberger]

Jc,

"Al. When you say the B-3 crossed the K55 too high, you mean higher than 600Hz right?"

NO! I am talking about the squawker / tweeter cross at what's normally 6000 Hz. It's determined by where the squawker driver poops out naturally. For the K55, that's around 6000 Hz. The later Cornwalls used a different driver (K51 or K53 or something!). Anyhow, wherever that driver poops out will be the high crossover. From the tweeter filter skirt it looks to be higher than 6000.

Al K.

[Al Klappenberger]

Dean,

The peak around 6 Khz that you mentioned is real except it's around 700 Hz. Another way to look at the 2 db dip in the middle of the squawkers range is to consider it as a peak at the lower corner of the tweeters range. That's probably how the brain perceives it. This could probably be worked out without to much trouble.

Jc,

BTW: Your inductor is now trimed to 1.6 mHy. See your private messages.

AL K.

[Hardhead]

Michael--

Not trying to throw a clod in your churn, but, while we're putting things in historical perspective, it may be worthwhile to consider that Klipsch designed successive versions of crossovers to match and balance whatever drivers he was using AT THAT TIME and that the drivers did change somewhat over the years. A better approach may be to look at what drivers you have and match them up to see if you have enough of exactly the same kinds to do what you're trying to do. Then you could figure out what crossover works best with--and was designed for--those specific drivers. I mean, why would you connect a K-77 Alnico tweeter with a crossover that was designed for a K-79 tweeter or a K-52 midrange with a crossover that was designed to work with a K-55-M?

I know that there are physical and electrical differences in drivers of different series. I also know that the best match in timbre and balance comes from using the same combination of drivers in each speaker. If I were going to spend money on re-doing crossovers so they all were sonically matched, I'd would want to start off with drivers that were sonically matched as well. That sounds like good sense to me but perhaps not to anyone else.

Although I have no personal knowledge of it, I think I remember someone posting on this forum that the K-55-V and K-55-M have at least some different characteristics, but I can't remember if it is impedance, efficiency, or what. I do know, however, that the K-77-M tweeter is a few dB more efficient than the K-77 Alnico. Putting a K-77 Alnico tweeter with a crossover that was designed specifically for proper balance with a more efficient K-77-M tweeter will cost you most of the K-77's output. The same may be true of the K-55-V and K-55-M; I don't know but I wouldn't be willing to take the financial and sonic risk. If the K-77 Alnico and K-77-M could be considered brothers because of their mechanical similarities yet sound so different, the K-77 series and the K-79 may be no closer than cousins and may sound even less alike, even connected to the same crossover. The same could be true of the K-55 series and the K-52's, etc.

I'm concerned that different drivers connected to the same crossovers may not sound enough alike to satisfy you after you've spent the money for the crossovers. Then if you do decide to match the drivers, you would have already bought the crossovers, and they may not be the version that makes those drivers sound best.

Matching the drivers for close matching of timbre and balance is one issue. Choosing the particular crossover variation that makes those matched drivers sound the best is, for me, the second step, not the first.

Good luck.

[Deang]

Everything you said is true and I agree completely. This is why I wanted Michael to take an inventory of what he has before he starts.

There is some debate about the Alnico K-77/ K-77-M differences. So, you say they really sound differerent -- interesting.

No question that the K-55-M is ever so slightly more sensitive than the K-55-V, but I don't think they ever put the K-55-M in the Cornwall or Heresy.

The K-79-K from the Cornwall II IS 3dB less sensitive than the K-77-M.

"Matching the drivers for close matching of timbre and balance is one issue. Choosing the particular crossover variation that makes those matched drivers sound the best is, for me, the second step, not the first."

I'm pretty sure you meant to say, "the first step, not the second.":)

[BiggerIsBetter]

"BB, are you 2 ch or HT listener? My theory is that with louder, the higher order filter is better, with softer musics, the 6db slope might very well be preferred. "

That may be generally true for power handling, I am commenting specifically on the "brightness" of the tweeter related to "modern' caps and the B vs. B-2.

I performed basic measurements before and after the changes I made. The measurements supported what I heard.

My baseline, stock B-2 with Aerovox caps, sounded very good and right on the edge of bight, but not. The measurements support this with near flat (though slightly elevated) responce through the crossover region (5-8K).

After the new metalized <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />dayton caps, bypassed with film daytons, it was bright out of the gate. Measurements showed a 2-3DB increase in the 5-8K area. I don't always trust HF measurements with my set up, but I could hear the test tones "jumping out" at those frequencies. After 2 weeks of break in, same measurements.

As an envolutionary move to a B for my cornscalas in the works, I KO'ed the inductor in the tweeter section. Sounded great, same balance as before the new caps with better detail and air. Measurements also showed the 2-3 DB hump was gone.

Again, these are not absolute terms as I cannot assess the condition of the original components that I replaced/removed.

But, in a home theater application I would think that bright is the last thing you would need. If you want a steeper slope filter and go with a B-2 with new caps, don't expect instant magic and be prepared to futz with it. If you really want steep and are willing to futz with it, I would try one of the other designs.

Bottom line, stay stock (or a rebuild the approximates the originals) or get crazy and be prepared for a bit of a road in order to reach a better place. I have choosen my road, I have a soldering iron, a good assortment of caps and I'm not afriad to use them []

[BEC]

Dean,

MY 1980 Heresys have K-55M, K-77M and type E crossovers.

Bob

[jwc]

"JC, Where did 75 ohms come from? The highest point in Bob's .pdf as it relates to the Cornwall is at 2500Hz with 13.9 ohms. If you calculate at 65 ohms using a Chebychev alignment with a crossover of 550Hz you get 4.47uF and 2.32mH. Remember that when you horn load a driver it changes the impedance characteristics."

Dean

Yes that .pdf is very helpful; thanks Bob. So that is the K55 on a K400 "wide open" has an impedence that averages around 11 - 13. So on tap 3 you are saying the relative impedence is around 65. I was using some info Bob had used when he hooked a K55 of to Tap 3 and got 74.5 ohms. I see your point about the change of impedence once horn loaded. I forgot about that. So I guess the bottom line is that I am never sure what impedance you guys are using to calculate a needed cap value. I must not even be close to seeing the entire picture yet.

Al

Thanks for the trimming the inductor for me. I have that ALK Cornscala-dbb made except for that one inductor you have. I guess you would say ALL the klipsch heritage networks are flawed in the sense they are allowing the K55 to run all the way to 20K Hz. This would include the AK-3 and the AL-3 right? I wonder if the AK-4 did this as well.

jc

[Al Klappenberger]

Jc,

The only netwrok I know of that limits the squawker upper range is the AK-4. It's bandpass curve looks like somebody sat on it!

Al K.

[Hardhead]

Everything you said is true and I agree completely. This is why I wanted Michael to take an inventory of what he has before he starts.

There is some debate about the Alnico K-77/ K-77-M differences. So, you say they really sound differerent -- interesting.

The Dope From Hope announcing the change from the K-77 to the K-77-M said the K-77-M was more efficient in the upper range, but, to me, it's also louder in the lower part of its range as well. I think that's the reason so many Heresy owners lower the autoformer taps on their tweeters. I believe Al K posted a response curve some time ago that showed how much louder the K-77-M was, even in its lower range, but I could have hallucinated again. The difference in the two tweeters is what I was talking about in our "harshness" posting of several weeks ago. I was talking about tweeter harshness and you were talking about midrange harshness.

No question that the K-55-M is ever so slightly more sensitive than the K-55-V, but I don't think they ever put the K-55-M in the Cornwall or Heresy.

I have a pair of 1983 Heresys that have the K-55-M in them. I got them used, but I don't believe the drivers had been switched.

The K-79-K from the Cornwall II IS 3dB less sensitive than the K-77-M.

"Matching the drivers for close matching of timbre and balance is one issue. Choosing the particular crossover variation that makes those matched drivers sound the best is, for me, the second step, not the first."

I'm pretty sure you meant to say, "the first step, not the second.":)

Nope, you match the drivers (step one), then you choose the crossover (step two). Sorry, didn't mean to write over your head. ; ) How about this: "For me the second step, not the first, is choosing the particular crossover variation that makes those matched drivers sound the best." Just doesn't read as well that way.

[colterphoto1]

Yes, we're in the fine tuning stages of xover philosophy here and I appreciate the recent input.

First, with regards to offbeat driver combinations, I have only one set of K79/K52K60/B3, that was purchased for center channel use. I could ditch them now, as I have stocked spare K77, K55/K600 setups that would be identical matches. I'd have to build a B2 network from scratch. I was considering those CWII parts just because I was able to obtain them and thought the K79 and K52 top end might be a little crisper for the dialog channel. Thoughts on this?

The only 'slight' mismatches then would be related to age, and would be the square vs round K33, K55M vs K55V, and K77 vs K77M. I think the first two are neglible 'mismatches' based on what I've heard, the K77 debate might require some testing or extended listening. Remember that I have 3 pair of cabinets and only 2 sets to make the HT. So chances are good that I can cobble together exact matches without too much trouble. A careful inventory will tell the tale there.

So I'm getting pretty close.

Michael

[Deang]

"Nope, you match the drivers (step one), then you choose the crossover (step two)."

Well, that's the way it's supposed to work, but since we know which drivers were used with each network we can do it either way. I understand what you're saying though and you're right.

"The Dope From Hope announcing the change from the K-77 to the K-77-M said the K-77-M was more efficient in the upper range, but, to me, it's also louder in the lower part of its range as well."

You just slid in one of my missing puzzle pieces, thank you. The harshness issue at higher SPL's is complex, but it's apparent there are some unhealthy things going on at the transition point.

"MY 1980 Heresys have K-55M, K-77M and type E crossovers."

They came from the factory that way? That doesn't jive.

Michael, at some point I just want to see a list of how many of each drivers you have, everytime I see the word "Cornwall" my brain shuts down.

[homemadeheresy]

this is the most informative link that i've found on crossovers to date []

[DrTUBE]

Good Day to the klipsch specialist

I have myself some concerns with CORNWALL crossovers, as I am planning to build a Cornwall replica. My question is roughly the same : I know that there is different "type B" Cornwall Xovers, but I dont have any schematic nor performances for it to be studied. my speakers are : K-792-KP tweeter, K601+K57K squawker, HH1501 woofer, T2A replacement Xformers. Can you give me these informations ?

May be my intervention in your conversation will seems a bit brutal to you , but I am brand new on this forum, and I apologize in advance.

Thanks and very truly yours

DrTUBE

[Malcolm]

FWIW I have seen Heresys with K-55-Ms. And from what I know of the ones I have seen, it is likely that they came that way from the factory. Frankly, it wouldn't surprise me a bit that Klipsch would put K-55-Ms in Heresys if they had product to ship and didn't have K-55-Vs. And I can certainly imagine it during the change from the K-55-V ultimately to the K-53-K during the last couple years or so.