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1986 AK-2 K-horns new to me.


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Recently purchased a mint set of 86 K-horns with AK-2 crossovers from the original owner.  Managed to get them in the house before the family saw them, and have since been told that they make the room more sophisticated ;)

 

Coming from a DIY background wondering what should be checked over on these to make sure I'm getting the most out of them.  Overall the sound is fantastic and very enjoyable, but not as detailed as my Bagsby continuum (bbc 3/5a style monitors), vocals feel a bit pushed back and the bass is not as powerful as I remember hearing on other pairs.  Paired to a primaluna integrated tube amp.

 

So far I've read up on but am not sure if the right way to go, or order of importance:

  • K55 back cover rattle
  • K55 Gasket replacement
  • AK2->Ak3 crossover upgrade/recap
  • Crites tweeter upgrade

 

 

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Most people would probably replace the capacitors -- they may be due  after 36 years.  Other people can post opinions as to what are the best.  The Crites people could be a source.

 

 

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I think you may need to get used to their sound.

I always find it confusing that some, mainly new owners, seem to describe as 'lacking' the precise thing that makes the Klipsch speaker profound. A 'pushed back' vocal/mid region should never be the description of the klipschorn/la scala mid... unless perhaps there is a mechanical issue or a room phase issue.

Vocals should be able to drill a hole in your head with the klipschorn if you wanted them to.

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Common internet advice is to convert AK-2 to AK-3. I did that on Klipsch's advice back in the mid '90's. I have since gone back somewhat to what I call the AK-2.5. 

 What the 2 does is knock down the mid horn by 2db relative to the bass and tweeter horns. The 3 corrects this. Both crossovers use the same caps for mid and tweeter so replace those in any case. Where the networks differ is in the shunt cap, caps on the woofer and the auto former and inductor on the mid. I like the mid 2db down. I padded down the tweeters 1.5 db for a better match to the mid and I like it. 

 I think old capacitors would be the number one thing. My K55m black plastic rear covers did start to buzz a few years ago, I reglued them. I also found chunks of sand cast crud in the K400 horn throats! Rat tail file and repaint. 

I did poly caps and hated them, it was too clinical and thin sounding and eventually I went with Russian MBGO and K75.

That is my stream of consciousness concerning my 30 year run with your same speakers. When all is right, they make a reference system you'll be proud of. They also show every upstream change easily, and are just plain fun to own. My 21yo musician son comes over once a week to school me in alternative styles of rock and jazz, he loves the Klipschorns.

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@Escoffee, congratulations on the acquisition and stealthily accepted insertion of your Khorns, lol.

 

The AK-2 has the T5A autoformer knocking the mids down -6db.

 

The AK-3 crossover uses the T4A knocking the mids down -4db.

 

The AA crossover, for comparison is set to -3db.

 

This may account for the perceived “pushed back” vocals.

 

I just built an ALK Universal clone and soldered the mids to the -6db tap and am finding a pretty even number of songs to sound way more recessed than I was used to on my La Scalas. Some are perfect, none are harsh, but a significant number of familiar tracks lack the “bite” I am used to. 

 

Pretty much any new caps you use will brighten up the mids because of lower ESR. You could pick up some new Daytons on the cheap as an experiment for starters. And if that doesn’t hit the spot look at bigger changes.

 

Upgrading a, for all intents and purposes, 40 year old tweeter produces a subjectively better presence too. 

 

The bass issue you mentioned has me stumped though.

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20 hours ago, Escoffee said:

Recently purchased a mint set of 86 K-horns with AK-2 crossovers from the original owner. 

 

Replace the fuses near the speaker wire binding posts on the side of the bass cabinets. Even if they are not burned, they are the weak link in the signal chain.

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20 hours ago, Escoffee said:

Crites tweeter upgrade

 

If you get those, you can re-use your existing factory Z-brackets and mounting rivets. Access to the tweeter is simplified by removing six screws and lifting off the very top panel.

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Thanks all for the great responses.  Hadn't even considered the Fuses being a factor as none of my other speakers have ever had them. Is it common to bypass these, or more common to just replace with a same rating unit?

 

I'll start with the caps and go from there, thanks for the link to @JEM Performance had not seen their name before. 

 

 

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On 6/11/2022 at 3:58 AM, garyrc said:

Most people would probably replace the capacitors -- they may be due  after 36 years.  Other people can post opinions as to what are the best.  The Crites people could be a source.

 

 

Thank you for the feedback, I do think ill start there.

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23 hours ago, Escoffee said:

Is it common to bypass these, or more common to just replace with a same rating unit?

 

New fuses should be the same rating as the old ones but, considering the fact that all the suggested aftermarket crossover "upgrades" are fuseless, use your best judgement when picking approximate replacement fuses at the auto parts store.

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How are all the connections? At the crossover and the drivers? And do you have good corners for your corner horns? Get foam pipe insulation and make sure the bass horn is sealed into the corner. And like @Schu said the mid range should be able to give you an earache.

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I purchased an Ak-2 recap kit today from jem.  Will measure with rew and my umik before and after to see what’s going on.  
 

with sealing the bass bin, I do have pretty square corners surprisingly.  I did see the black narrow back against the corner has some kind of rubber seal, is that what you mean for sealing it to the wall? If not I’m not sure what would be sealed up, but happy to try!

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13 hours ago, Escoffee said:

I did see the black narrow back against the corner has some kind of rubber seal, is that what you mean for sealing it to the wall? If not I’m not sure what would be sealed up, but happy to try!

 

Yours should look like weather stripping on a storm door. The idea is to get it really tight against the walls. Others often suggest pipe insulation or pool noodles to provide more spongy-ness. I went the pipe insulation route with my 86/87 AK-2's. I had good luck tipping the khorn slightly toward me from the top and forcing the bottom hard into the corner then standing the khorn up straight....if you can visualize that. There is a cut out at the bottom for baseboard/molding, with it tipped forward it can help you get closer. I had a purpose built room with perfect corners. They were as tight as you could get them.

 

Interestingly enough I never thought my Khorns had the same bass response as the handful of others I've had a chance to listen to. I "upgraded" XOs from long time forum member and still never got where I thought I should be. After 14 years of loving the midrange we parted ways. Moved to bigger horns for a time and then open baffle. Can't say that I miss the Khorns after going 2-way active. I am glad for the time we had together.

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I was able to take some measurements (in room, no idea if a traditional 3' center measurement would work with this design) to see how they are interacting with the room, not surprised with the results vs listening impressions.  I have a cap kit from JEM I will try first, but may look at an ak-2 to ak-3 upgrade to hopefully level out that midrange.

 1370444081_LRinRoomOriginalcrossoverSPL.thumb.jpg.2fd4361c1f062a2e121a4624167ef5e4.jpg

original k horn Right impedance.jpg

R in Room Original crossover Spect.jpg

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