Is this Kappa 8 crossover mod nuts or for real?

Arkay

Lunatic Member
I ran across this post on another board, when "researching" Kappa speakers:

As a long time Kappa 8 owner I can strongly recommend a simple bypass modification to the crossover that makes the speaker easy to drive and actually better with a more natural and full bass response. Simply unsolder or cut one side of the 12.5 mh coil from the crossover and solder in a shorting bridge across any one of the three 500uf (1500uf total) capacitors that are the first thing after the woofer binding posts. This takes the 'reactor' out of the woofer circuit. Now your amp will just see a common 4 ohm load and the bass will be very natural without the 'thump' where that cap and coil reactor stores a charge and throws it at the woofer while melting your amp in the process. I listened carefully using the famous Hok-Man Yim Poem of Chinese drum CD and it actually hits harder with better decay after the mod and the amp doesn't overheat in the slightest. The Kappa 8's punch that track harder than anything I have owned with just one 12 per side. If you want to keep protection against a DC short from your amp, ignore shorting out the (series) capacitor, but by all means get that evil 12.5 mh (shunt) coil out of the woofer circuit.


As much as I'd like to believe that a simple modification could thus "improve" the Kappa 8s, wouldn't this potentially defeat the purpose of the Watkins dual-VC concept, or at least have other serious implications for the crossover behavior? (I don't have the crossover circuit design in front of me, and am not entirely familiar with it, but I'm guessing from what I remember that this would ruin the Watkins behavior.)

Has anyone tried this mod before? Is this mod the road to :banana: or just utterly :screwy:?

(Sorry if this has been discussed before; I didn't find it. If it has, please just provide a link to the thread, rather than repeat stuff here.)
 
I would be tempted to modify the crossover for tri-amping of eliminate the passive crossover altogether and go with an active crossover. I wonder if it has ever been done?
 
That's funny i tried that same mod on my 8's and 9's a few years ago, i thought the speakers sounded better with the mod but to me the bass output was greatly diminished compared to stock so i left them stock, i bet if you bi amped the woofers with an amp with a slightly higher gain than the high frequency amp your mod would really sound way better than stock.
 
Arkay. Kappas don't have Watkins woofers although it would be a very cool if they did.

This thread surely grabbed my attention. Probably not going to try the mod.
 
If you already run your Kappa 8's in extended mode, removing the 12.5mH coil won't do anything. It's only in circuit if extended mode is switched off. At least, according to the schematic.

Also, while bass could benefit from bypassing the 1500uf capacitor bundle, I wouldn't. It's basically acting as a rumble (high pass) filter on the woofers. Bass 'may' improve if you bypass them. But, these caps are acting as a DC filter too. So, they act as a safety feature. If anyone uses an amp that could malfunction, and send a DC signal to the speakers, those caps would save your speakers.
 
That's funny i tried that same mod on my 8's and 9's a few years ago, i thought the speakers sounded better with the mod but to me the bass output was greatly diminished compared to stock so i left them stock, i bet if you bi amped the woofers with an amp with a slightly higher gain than the high frequency amp your mod would really sound way better than stock.

Hello Okee: I am planning of bi-amping my K9s and your post caught my attention - especially your 'recommendation' of using 'different gain' amps. Wouldn't that make your SQ 'confused'?

I'd like to learn more about bi-amping strategies using the passive xover.

TIA,

egay
.e.
:music:
 
I discovered by passively bi-amplifying my QLS-1s with amplifiers with left and right gain controls, I actually have more control over bass output and have found allotting more power to the low end is an improvement in sound quality.
Vertical bi-amplification even better for me
 
If you already run your Kappa 8's in extended mode, removing the 12.5mH coil won't do anything. It's only in circuit if extended mode is switched off. At least, according to the schematic.

Also, while bass could benefit from bypassing the 1500uf capacitor bundle, I wouldn't. It's basically acting as a rumble (high pass) filter on the woofers. Bass 'may' improve if you bypass them. But, these caps are acting as a DC filter too. So, they act as a safety feature. If anyone uses an amp that could malfunction, and send a DC signal to the speakers, those caps would save your speakers.

I did the removal of the 12.5mH (but did not bypass the caps) mod last night on my Kappa 8's. My Rotel 1090 can go quite a bit higher now before going into protection and it runs cooler. I did not notice any significant changes in the bass response.

I plan to put in a SPCO switch that will provide normal mode, extended mode and allow the 12.5mH coil to be bypassed. This will let me compare the mod's sonics quickly rather than than relying on my half hour change over memory.

The stock Normal/Extended mode switch simply bypasses the 5 ohm, 50W resistor. It does not bypass the 12.5mH inductor which is always in circuit.

The previous owner of my Kappas did some work on the xovers and got ohms law wrong. He replaced the 5 ohm resistors and apparently couldn't find 50Wer's. He correctly put two 25Wer's in parallel to cover the 50 watts but incorrectly used 2.5 ohms think the value summed like the wattage. So the resistive value was 1.25 ohms rather than 5 which meant they were always running closer to extended mode. Explains why I didn't hear a difference and my amps still went into protection mode at the same volume setting, regardless of the switch's setting.
 
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Dont do that

NUTS

just find the right amp to power this fantastic speakers


i use a sansui au-9500,i impressed about the level of the soundtage and how realistic the sound is!!!

its like you are there!!!
 
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M80 is described as 2ohm when use B+C terminals (1a.jpg).
Can I connect K8 as shown on photo k8-v2.gif, means "low" to B terminal, and "Hi+mid" to C terminal of the same amp?

regards, Tom
1a.JPG k8-v2.gif
 
What do you think? Can I run those guys with a Sansui G22000
I wouldn't, you can get a pretty damn nice power amp (like an Aragon 4004) for a lot less than the value of the G22000, with no risk of blowing it. If you want, use the Sansui as a preamp.
 
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