Replacement for k77

[pzannucci]

Hello,

I'm looking for a drop in replacement for the k-77 tweeters in my khorns. I have a set of AK-2 networks. The K-77 is too hot on this vintage khorn vs the older round magnet tweeters. The main requirements are 1. drop in replacement (minor crossover tweeks ok), 2. cleaner and slightly lower output (1-2db - quality comparison against Aurum Cantus G1 ribbons in my home builts) and 3. might be able to lower the crossover frequency so I can cut off the k-400 and lower the mid/high beaming factor since I can't sit directly on axis with horns in the corners. Any thoughts would be appreciated.

Thanks,

Peter Z.

[mark1101]

Have you heard about the CT-125 tweeter from BEC (on this forum)? It sounds like that may be what you are looking for. No other modifications are necessary. It was desigined as a drop in replacement for the K-77.

Others will chime in with more complete information and their experiences.

I happen to have 2 pair and a single available. One pair has only about 10 hours on them. All are in perfect condition and look brand new.

If you become interested email is the best way to get a hold of me.

Good luck finding your solution.

[Hardhead]

Peter--

Since you note that the K-77 "is too hot . . . vs the older round magnet tweeters," I'm assuming that you have the square magnet K-77's, more particularly named the "K-77-M." Is that assumption correct?

[pzannucci]

Hardhead,

Exactly, k-77m. I had two pairs of khorns before these and have always loved them (alnico 77s). I purchased these khorns a few years ago and never warmed up to them because of the hot ssss of the tweeter. That's why I went with home built. Now hearing the quality of something like a G1 ribbon tweeter though missing the wonderful lower end of the khorns has made me want to modify the khorns but importantly, keep the enclosure in tact. Also, lowering the beaming would be a big plus for my seating position.

Thanks,

Peter Z.

[Guest " "]

1. drop in replacement (minor crossover tweaks ok),

Bob has a drop in replacement, but some folks report that it is brighter.

2. cleaner and slightly lower output (1-2db - quality comparison against Aurum Cantus G1 ribbons in my home builts)

I am not sure if the EV TW-35 has a slightly lower output than the EV t-35, t35A, t-35b, etc. It has a smaller magnet, but uses the same voice coil. I have the data on hard copy at home. Ill take a look to see if it has any useful info.

3. Might be able to lower the crossover frequency so I can cut off the k-400 and lower the mid/high-beaming factor since I can't sit directly on axis with horns in the corners.

This is a compounded spec. The k-77 can be crossed over as low as 3500hz. The same diaphragm in an st-350 can be crossed over as low as 3000hz. The new AL/k-4 xover use 4500 and 400/450 as the xover frequency, but the AL/k-4 is a steeper sloping xover than the AK-2. If the beaming factor is the primary objective. recommendation would be to look into the 511b horn or Als wooden trachorn.

[mark1101]

There are a couple of ways to get rid of the beaming (and hot tweeter), but it depends on how willing you are to part with the "classic Klipsch" sound.

1) Change the networks. You need to go to an extreme slope on the top end introducing a squawker bandpass if you want to really reduce the beaming of the squawker significantly. ALK extreme slope networks are highly recommended for this and the classic Klipsch sound is retained. This really works well and improves the imaging and power handling significantly. The midrange hash all goes away. I know well about this option.

2) Change the squawker. There are a few different options out there such as the Altec horns or Trachorns. This works best I hear but requires additional mods to the networks and the sound is no longer like a Khorn or other Heritage speaker. I don't know very much about this option.

My recommendation is to not change the tweeters but instead consider extreme slope networks. They include adjustable tweeter attenuators, as well adjustable squawker settings. http://alkeng.com/

[Guest " "]

"They include adjustable tweeter attenuators, as well adjustable squawker "

Those work very well.

Al also sells the adjustable tweeter attenuator seperately.

[pzannucci]

Mark1101 and speakerfritz,

I appreciate your thoughts and info.

What I remember of my mid 70's vintage (k55-v and alnico k77) was that they were somewhat more subdued in the midrange and especially tweeter area. I would like to get my current pair back to mid 70's sound with possibly the benefit of less beaming, hence the reason for the tweeter mod. I would like to soften the hard edge and clean up the tweeter so it sounds more like the earlier khorns. I think the folks that reported the ct125 was hotter were likely using the alnico k77 and not the mud.

Thanks,

Peter Z.

[mark1101]

Peter,

I have all new style drivers in my Khorns and Lascalas. But I do have a center channel LaScala and a pair of corns that have all alnico drivers.

You are correct that there is a difference, a more mellow or subdued sound about the alnico drivers. Maybe I'm not describing it as well as I could, perhaps slightly smoother. I like that difference myself.

But....when I updated my tweeter diaphragms and networks and brought everything back to spec that difference narrowed. They are not that far apart actually, although I acknowledge there is still a minor difference. It is audible.

This is another reason I suggested not changing out the tweeters and instead "adjusting" the output with new networks.

I removed all the CT-125s from all my Klipsch speakers after enjoying them for a period. They are a really good tweeter. But they are not a match in tonality and output for any of the K-77s. They are a replacement and they don't sound like a Klipsch speaker.

If you are after the "classic Klipsch" sound I referred to earlier (and it sounds like you are), the subtle differences that you descibe from certain vintages of Klipsch will be completely lost if you change drivers.

If you want "better" or different sound, all bets are off and driver changes can make big improvements.

I've found over time that I am of the type to squeeze the last ounce of performance out of the original products to strive to retain the classic sound but on a higher level.

[markgod]

Hello,

I'm looking for a drop in replacement for the k-77 tweeters in my khorns. I have a set of AK-2 networks. The K-77 is too hot on this vintage khorn vs the older round magnet tweeters. The main requirements are 1. drop in replacement (minor crossover tweeks ok), 2. cleaner and slightly lower output (1-2db - quality comparison against Aurum Cantus G1 ribbons in my home builts) and 3. might be able to lower the crossover frequency so I can cut off the k-400 and lower the mid/high beaming factor since I can't sit directly on axis with horns in the corners. Any thoughts would be appreciated.

Thanks,

Peter Z.

Peter,

Why not just buy an old pair of the round K77 ,if that is the sound you like? Or am I missing something here. Assuming that is what you like ,how much would you be willing to pay for them?

Mark G

[Deang]

You should at least try Bob's CTS-125 since it drops right in. $150 for a pair is a very reasonable investment. No, it's not going to have the smoothness of the Aurum Cantus G1, but you may still like it. Also, Bob's replacement driver will better accomodate a lower transition point. I have mixed feelings on dropping the crossover point. It sounds good both ways, but the original crossover point sounds more seamless to me -- that is, the tweeter seems to have less of a life of its own.

[JohnA]

peter,

You should really look at Bob Crite's tweeter. As I remember, it

is not hotter, but in fact the opposite at 102 to 103 db/w/m.

Your '70 horns had Type AA xovers that cut the 105 dB K-77's output by

as much as 3 dB. I normally use upgraded Type AA xovers because

I, too, like the 70s sound, like I first heard.

Bob's tweeter sounds like just what you want. If you don't like them I'll buy the pair from you.

[mark1101]

John,

I still have 3 available if you really want Bob's tweeters. They are in perfect condition.

[Marvel]

Bob's tweeters are a vast improvement in my LS. Took all of ten minutes to change them out too. Mine were the mud magnet K77s.

[pzannucci]

I have just recieved them yesterday. I had read that the driver Bob uses is very good but never wanted to have to modify my my cabinet to accomodate the horn lense options. These should just drop in provided the old k77s come off their frames easily. I'll need to do some crossover mods though I won't do that until after some initial listening and break in.

I had purchased a set of Bel Canto REF1000 amplifiers and hooked up the k-horns when I was finishing up my cabinets on my homemade speakers. I was floored by the bottom end of the khorns when hooked up to the REF1000 amps. The Bel Canto sound was very very similar to my tubed Rogue Audo 88 (except for the punch and bottom end authority)so I figured that I would take another look at doing modifications to the khorns. At 500-1000 watts per side, these are no SET amps but if you ever listen to the combo, you'd be amazed.

I'll keep you posted and thanks

[pzannucci]

Well changed out the k77s with the ct125s and there was some change but not very pronounced. The real changes came into effect when I changed the crossover. I dropped down the tweeter about 1 or so db, added a second order acoustic filter on the mid, and third order acoustic on the tweeter at around 4khz. This made a major transformation on my khorns. These changes with even a hacked together crossover will probably allow the khorns to become my primary speakers (I'll have to find a new home for my handbuilts). Well worth the expense and time. Just have to figure if I want to take the time to optimize the networks. [*-)]

[J.4knee]

Another option you might want to consider is to change your sqawker horn to Al's 400 HZ Trachorn.

[consistent]

Hang on a little longer say 50 plus hours and you'll find Bob's tweats 'open up' some more and you will get a more pronounced top end, sweeter than the k77.

Cheers