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Jim Pearce

putting a 4 ohm Tweeter into KLH 6

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From tempest series PS-8, measures 4 ohms.

Intend to do no modifications but will use one amp fuse inline and a Sansui 8080.

What do you guys think?

It is a direct fit; will drop right in.

Also, what about the same thing with an AR 2ax?

I have done this before with a Polk RT 16 with excellent results.

 

Edited by Jim Pearce

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Hey Jim

I don't think it will be a problem but will wait to see what guys with more tech savvy say

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Thanks, apparently you understand but I do not see the beginning of my question which says I'm going to use a substitute tweeter.

(Seems to have disappeared during my edit process which I did not realize, sorry.)

So what about driving these lovely speakers with something like what shows 75 watts on the meters of an 80 watt receiver please also, guys?

 

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The back of my KLH Six is labeled 8 ohms. I assume that means the tweeter has nominal rating of 8 ohms.

If you replace an 8 ohm tweeter with a 4 ohm tweeter the crossover frequency will double for a first order filter such as used in the Six. If you do not change the cap values, you will end up with a hole in the frequency response between the woofer crossover frequency and the new tweeter crossover frequency. That is, the woofer will roll off at its original 1500 Hz crossover frequency and the tweeter will pick up at 3000 Hz, twice the woofer's crossover frequency. 

When replacing drivers, if an original, OEM driver is not used, the replacement driver should match the original TS parameters as closely as possible. If you do not want to rework the crossover, you need to at least match the driver impedance at the crossover frequency. 

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2 hours ago, RTally said:

The back of my KLH Six is labeled 8 ohms. I assume that means the tweeter has nominal rating of 8 ohms.

If you replace an 8 ohm tweeter with a 4 ohm tweeter the crossover frequency will double for a first order filter such as used in the Six. If you do not change the cap values, you will end up with a hole in the frequency response between the woofer crossover frequency and the new tweeter crossover frequency. That is, the woofer will roll off at its original 1500 Hz crossover frequency and the tweeter will pick up at 3000 Hz, twice the woofer's crossover frequency. 

When replacing drivers, if an original, OEM driver is not used, the replacement driver should match the original TS parameters as closely as possible. If you do not want to rework the crossover, you need to at least match the driver impedance at the crossover frequency. 

My main concern is the potential for damaging hardware.

Incidentally I am told that these particular tweeters go quite low.

I don't know what anything else you said means.

Ohm, I don't even know Um's Law.

Seriously, bro I don't know how to solder.

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On 11/15/2019 at 12:08 AM, Jim Pearce said:

My main concern is the potential for damaging hardware.

Incidentally I am told that these particular tweeters go quite low.

I don't know what anything else you said means.

Ohm, I don't even know Um's Law.

Seriously, bro I don't know how to solder.

Seriously, if what I wrote above does not mean anything to you, I suggest you replace the tweeter with an exact replacement. It is not enough that that a tweeter physically fits into the hole in the baffle. The replacement tweeter must match the original tweeter electrically. Indiscriminately replacing drivers in speakers will most likely result in less than desirable results. 

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What is the risk for any damage to any of my components and what do I need to avoid doing that will damage the loud speakers with this mod?

I am simply wanting to try it and see what it sounds like.

Many thanks to all of those that replied!

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1 hour ago, Jim Pearce said:

What is the risk for any damage to any of my components and what do I need to avoid doing that will damage the loud speakers with this mod?

I am simply wanting to try it and see what it sounds like.

I'm sticking with my original answer: No problem.

The KLH Model Seventeen and Twenty loudspeakers are identical: Same cabinets, exactly the same crossovers, exactly the same tweeters. The only difference was the woofer. The Seventeen used an 8 ohm woofer and the Twenty used a 4 ohm woofer. Therefore the 17 was an 8 ohm system and the 20 was a 4 ohm system.

AR used exactly the same tweeter in the 8 ohm AR-2a and the 4 0hm AR-3.

I do not think there will be any dire consequences.

Kent

PS: Although I agree that "Indiscriminately replacing drivers in speakers will most likely result in less than desirable results" and this IS a classic speakers forum where we try to preserve the original chacter of classic speakers, your experiment won't damage anything. This whole thread may be more appropriate in the "tweaks and mods" section of the forum. 

So while I agree with RTally that the best thing is to keep it original (ESPECIALLY with KLH Sixes, which Henry Kloss said were the ones where he "got it right"), your experiment won't kill your speakers or your electronics. It just won't sound right.

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9 hours ago, JKent said:

I'm sticking with my original answer: No problem.

The KLH Model Seventeen and Twenty loudspeakers are identical: Same cabinets, exactly the same crossovers, exactly the same tweeters. The only difference was the woofer. The Seventeen used an 8 ohm woofer and the Twenty used a 4 ohm woofer. Therefore the 17 was an 8 ohm system and the 20 was a 4 ohm system.

AR used exactly the same tweeter in the 8 ohm AR-2a and the 4 0hm AR-3.

I do not think there will be any dire consequences.

Kent

PS: Although I agree that "Indiscriminately replacing drivers in speakers will most likely result in less than desirable results" and this IS a classic speakers forum where we try to preserve the original chacter of classic speakers, your experiment won't damage anything. This whole thread may be more appropriate in the "tweaks and mods" section of the forum. 

So while I agree with RTally that the best thing is to keep it original (ESPECIALLY with KLH Sixes, which Henry Kloss said were the ones where he "got it right"), your experiment won't kill your speakers or your electronics. It just won't sound right.

Great response, Kent. I agree completely.

"Rated" impedance and/or dcr are not necessarily at the top of the list of considerations in this case. Mechanical properties and unique response characteristics often supersede impedance when substituting drivers in pre-existing designs. Other variables pertain to crossover slopes and level control characteristics. It certainly won't hurt anything to experiment, though the original driver is almost always the best replacement choice in a proven design.

Roy

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Sir... you are on it.

I continue to view your historical writings and see that you continue to be very active and as knowledgeable as anyone probably, at my level anyway you are and have been for quite some time my reference and I thank you.

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Roy,

Your answer is as expected.

Gratifying to have you chime in. Same to you JK on both accounts

I am especially proud to own several pairs of the sixes. Learning what HK said after I bought some of these speakers was pretty cool, loved them instantly when I first heard them.

I know I'm pretty foolish to try and improve on his design.

My high frequency hearing is poor, very.

I guess I'm trying to compensate.

 

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