KHorn stock upgrades, life of Klipsch stock caps, and EQ:

[garyrc]

Thanks for all the help you have given me in the recent past....

Here are a few questions about KHorn stock upgrades, life of Klipsch stock caps, and EQ:

I have AK-4 KHorn stock upgrades. Does anyone know:

1) Of the AK-4 and the AK-5 mod (lower tweeter level -- can be achieved by the minor change of losing a resistor in the AK-4) which one is the nearest to flat? I wonder if the mod is primarily a way to be gentle to bad program materiel by reducing treble slightly, while depriving the best program material of some sparkle? Does anyone know if the treble reduction (in the AK-5 mod) varies with the frequency within the K-77-F's assigned range, or just turns the whole thing down like a ("shelving" ???) pad?

2) I've heard that there is some EQ factory built into the stock AK-4s. Other than bringing each driver in at the correct level, and imposing the crossover slopes themselves, I wonder what's been done ... I've heard about the cutting off of two small peaks and one dip in the K-33-E range, but can anyone describe the EQ, if any, in the midrange and tweeter range?

3) For Klipsch stock networks, is it feasible to set up a very approximate cap replacement schedule? When should I check (how?) and/or change the caps in my new AK-4 stock K-Horn upgrade networks, in my year old Belle center channel, and in my 1988 Heresy II surrounds?

4) Do caps change because of age alone, use, or disuse?

Thanks,

Gary

[Daddy Dee]

Hi Gary,

I am sure there are folks here who can chime in on the specifics of the

AK-4 and AK-5 networks. These are quite sophisticated networks of

higher order filters than in the old A and AA networks.

One thing that is impressive about the AK-4 crossover is that it

accomplishes the tweeter to mid transition at 4500hz. This makes the

K55 sound smoother. I don't comprehend how the higher order filter

protects the K77 going down to reach 4500hz, but it is my best

understanding that this would not be advisable with a K77 and say a

type A network. That is some impressive engineering, IMO, and makes for

a very sweet sounding Khorn.

On the life of caps, most of the crossover rebuilds referred to on the

forum are on crossovers twenty and thirty and more years old. The life

of crossovers, I think, would be measured in decades. My very lay

understanding of crossovers is that the caps don't have to work very

hard, there is so little current coming through them. I don't think the

life of a cap would be influenced by it's use or disuse in a crossover.

I know that NOS caps are bad news, because they have become resistive

sitting in their dark boxes on a shelf somewhere.

The caps in the AK-4 crossovers are a different variety than the old

caps in a can on the old crossovers. Don't know how the difference in

design would affect the expected life, but I doubt it would be any

shorter than the old rascals.

[Deang]

Hi Gary -- well, this is actually the first I've heard of an AK-5, and I haven't heard anyone else mention, so -- you are the first to bring it here in name. So, I don't think anyone is going to be much help here in answering your questions about what the differences are between it and the AK-4. If I were to take a guess, I would say they probably didn't 'drop' a resistor, but probably adjusted the value. It's also more than possible that other changes were made as well -- but without seeing the schematic -- there's no way to know. Klipsch doesn't release schematics of current production speakers, so the only way to know for sure is to be in possession of an AK-5, and reverse engineer it and make a schematic (which is what I did with my AK-4's). I wouldn't fret about it. Regardless of what they did, the chances of you liking the change is about the same as not liking it!

In the AK-4, EQ is limited to the woofer section, and like you said -- it knocks the two nasty peaks down to flatten the response.

The AK-4 uses metallized polyester film capacitors -- and they'll probably be good for at least thirty years.

[garyrc]

Thanks, Daddy Dee, and Dean G, for the info. If anyone out there knows which way is most nearly flat, I'm still interested.

With the Klipschorn AK-4 upgrade, I think the K-77-F is allowed to get 4,500 Hz, but with a very steep roll off below. I once had the somewhat similar EV T35s and x 36 crossovers allowing the T35 to get 3,500 Hz with a 12 dB/octave crossover, and never damaged the tweeters, even with very high SPLs. I hear that the K-77-F slope in the AK-4 is considerably greater than 12 dB.

Steve Phillips (quite a helpful fellow) has called the latest version AK-5 twice, but I thought I picked up a nuance or two that "AK-5" might be a nickname. Too bad emails don't let us hear tone of voice. He did say that there is a little less tweeter, and he believes that all upgrades being shipped now are up to date in this regard. Mine is an AK-4, though, and that's fine. I would want to live with the AK-4 a good long time, and try it in our new music room (being remodeled -- slowly -- now) before making any changes -- if ever.

I'm cautious because of what I went through with JBL years ago. They recommended a lower setting than that which would measure flat on one of their tweeters (without really saying it was somewhat attenuated compared to flat). On good program material I was constantly crawling behind the speaker and turning up the pot. Later, in a conversation with one of their engineers, he revealed that the flat setting was indeed higher, but too many people complained about screechy highs on LPs that were slightly distorted in the treble. He said they used flat with good master tapes. I turned the tweeter up to approximately flat and left it there, and my direct-to-disk, and other good LPs sounded much better. I tended to not play the screechy ones, or used those nearly extinct devices, the tone controls.

[SilverSport]

...at Indy last year, Steve mentioned that the 2006 K'Horns would have AK-5's in them and said (IIRC) that the "upgrade" was minimal...I have the AK-4 "upgrade" as well...all new drivers and horn (K-401)...I am pretty happy with them but would like to know more if it is found...

Bill

[Deang]

This stuff is so room and system dependant, there ain't no anyone can say one network, or network mod is "flatter" than another. If you want flat, buy an EQ with a built in RTA.