KLH 17's masquerading as 6's?

[Tim D]

I believe the KLH service bulletin for sealing the woofer also mentioned to seal the dust cap too. Use the minimum goo to do the job. Overapplying the goo will stiffen the surround and hurt the resulting sound quality.

Assuming the original foam gaskets aren't doing the job anymore: I use Mortite plumbers putty that comes in rolls where you can peel off how much you need from the roll. When I put the putty down I do it in such a way that the putty is on the basket side of the screws under the flange to avoid air leaks from around the screws. In fact I usually have the putty go on both sides of the screw with two ropes of putty one inside the screw and one outside.

It's good to check the cabinet box itself doesn't have leaks. If the corner joints of the box are still tight then you are probably fine, but abused speakers or speakers that have water damage can often have the corners separate ever so slightly - which would cause air leaks.

 

[RTally]

Caps replaced and surrounds sealed! I need to figure out a couple more components of my system before I can test them properly, but early indications are good. I'm unsure whether I've sealed the surrounds properly though. I've read that when depressed, the woofer should return slowly. It returns more slowly than when not installed in the cabinet, but not by a lot. (See the video below.) Should I expect a slower return?

Testing seal on woofer surround

• Trygve
• Jun 24, 2021

Nice video, but your testing method needs work.

First, you should always press evenly around the dustcap, not off to one side as it looks on the video. By placing 3 or 4 fingers around the dustcap and pushing, the cone, and more importantly the voice coil, moves linearly. By pressing off to one side, the voice coil will not move evenly in the gap and you may even hear the voice coil scrape the side of the air gap as the cone moves. You will not damage the cone by pressing unevenly, but it is a good practice to always press evenly.

Also, to test for the cabinet seal, press the cone and HOLD for about 10 seconds before quickly pulling your hand away from the cone. By pressing in and immediately releasing, the pressure in the cabinet has not equalized and the compressed air in the cabinet will press the cone back to its original position. By pressing and holding, the air inside the cabinet has a chance to equalize so that when the cone is released, the cone's movement is controlled by how quickly air can get back into the cabinet.

If the cone returns in less than 1/2 second, there is an air leak somewhere. It could be the surround, the dustcap, the woofer seal to the cabinet, the tweeter seal to the cabinet, the back terminal plate seal, or even the cabinet corner seals.

If the cone takes more than 1 second to return, you are good to go. There may be a very minor leak, but not enough for me to worry about.

If the cone takes more than 2 seconds to return, you have a very good seal. There must be some leakage, otherwise the cone would move with atmospheric pressure changes, just like a barometer.

 

[hornbostel]

Here's an image of one of my Twenty Threes. It says KLH 10 next to the tweeter.
View attachment 2247031

I am not sure you meant to say ‘KLH 10’. I didn’t see that in your pic. I have a pair of LLH 23 and they are unique. Can’t mistake them for anything else.

As a matter of historical reference there was in fact a super short run of a ‘KLH 10’ speaker. This particular speaker was also produced as the Realistic/Radio Shack ‘Solo 10’. From what I understand from friends this is a greet speaker. I’ve never seen or heard a pair in person. A unicorn for sure!

 

[alteclipsch]

I am not sure you meant to say ‘KLH 10’. I didn’t see that in your pic. I have a pair of LLH 23 and they are unique. Can’t mistake them for anything else.

As a matter of historical reference there was in fact a super short run of a ‘KLH 10’ speaker. This particular speaker was also produced as the Realistic/Radio Shack ‘Solo 10’. From what I understand from friends this is a greet speaker. I’ve never seen or heard a pair in person. A unicorn for sure!

Yes, I meant to say "KLH 10." In the posted image of my Twenty Three there is clearly a stamp of "KLH 10" near the tweeter, between it and the upper right velcro patch. Similar to the "KLH 17" stamp on the OP's Model Six. Nothing to do with the Solo 10 or anything else.

 

[Dswankey]

I am not sure you meant to say ‘KLH 10’. I didn’t see that in your pic.

Here it is

 

[Trygve]

OK, thanks for the feedback. I used some insulation rope caulk to seal both the woofer and tweeter:



Seems to give a good seal. The inside corners of the case look really clean and sealed, and the crossover plate looks quite tight. Despite this and an improved test method the woofer cone still returns in ~1/2 second. Maybe a second coat on the surround and cap?

I also hooked them up to give them a go after the recapping. The recapping helped, but unfortunately they still sound somewhat muffled, like I'm hearing the singer's voice from down a tunnel. I also don't notice any difference among the three settings on the high frequency switch. Any thoughts on other tests I could do to figure out why that might be?

Thanks!

 

[Tim D]

I'd start by checking the tweeter then move on to checking continuity through the switch in each position and then if it still didn't work I'd start re-checking the wiring for accuracy.

 

[dly66]

Second a coat on the dust cap if you just applied sealer to the surround. Another place they can leak, dust cap material looks to be woven.

 

[Trygve]

Second a coat on the dust cap if you just applied sealer to the surround. Another place they can leak, dust cap material looks to be woven.

Yep, coated the dust cap as well.

I'd start by checking the tweeter then move on to checking continuity through the switch in each position and then if it still didn't work I'd start re-checking the wiring for accuracy.

Aha! Opened them up (again!) and hooked up a multimeter to the tweeter - nothing (no connectivity). I removed the grill and sure enough, one of those hair-thin wires is broken. I tried to solder the wire back together and just made things worse. I have a hunch it's just way beyond my fledgling skills, but even after cleaning the wire as best I could I couldn't get solder to stick to it. At any rate I think I've damaged one of the tweeters beyond repair with my failed attempts.

I'll try again with the other tweeter, but I'm now in the market for a pair of tweeters. Model 6, 17, 20, 30, or 33, I'm reading. I'll keep an eye on ebay and craigslist, but any suggestions on where else to look for these?

 

[Trygve]

Just found a listing on Craigslist for a pair of tweeters. $50 for the pair. Is that reasonable? (Edit: sorry, guess we can't talk about money here.) I'm seeing what I think is honey-colored adhesive, so maybe they're the model 5 version? From what I'm reading (here) the model 5 version might actually be better, so it might not matter which?

 

[Tim D]

Not sure about tweeter compatibility with 30 and 33, but definitely compatible across 6, 17, 20. Others can correct me where I'm wrong. They come up on the big auction site from time to time. Just be patient.

 

[Tim D]

You can't go by the adhesive to tell which model. You'll need to measure the size of the woofer and get pictures of the magnet on the woofer to determine. Also model 5 are 3-ways, so where are the midrange drivers in the sale?

Assuming they turn out to be for the model 5, you can get by with the model 5 tweeters, but there is a slight difference from the others. First you will want to check the tweeters before purchasing if it is on CL as I assume you will pickup. You'll want to see if the magnet will fit through the holes cut for the 17's, but I think the bolt pattern is the same.

Can't comment on the price as that will throw your thread into the Dollars and Sense area. It's in the rules to not talk about price anywhere else. Not sure why, but it is the rules.

 

[Trygve]

Thanks!

you can get by with the model 5 tweeters, but there is a slight difference from the others.

Sorry to confuse matters. Looks like these are woofers and tweeters from model 23s. So, the same tweeters (as I understand it) as 5s, but that's why there are no midrange drivers. What do you mean exactly by "get by"? I can understand a desire to maintain original build intent. Any thoughts on the sonic effect of using the other tweeter type? If, as is claimed here (#29), the model 5 tweeters sound slightly better, I'm inclined to use them if they're otherwise compatible.

I plan to bring a multimeter to check the resistance on the tweeters. Any other tests I can perform in someone else's driveway to verify that they're in good condition?

 

[Tim D]

Thanks!



Sorry to confuse matters. Looks like these are woofers and tweeters from model 23s. So, the same tweeters (as I understand it) as 5s, but that's why there are no midrange drivers. What do you mean exactly by "get by"? I can understand a desire to maintain original build intent. Any thoughts on the sonic effect of using the other tweeter type? If, as is claimed here (#29), the model 5 tweeters sound slightly better, I'm inclined to use them if they're otherwise compatible.

I plan to bring a multimeter to check the resistance on the tweeters. Any other tests I can perform in someone else's driveway to verify that they're in good condition?

Slight sonice difference between the 5/23 tweeters and the 17/20/6 tweeters. As long as the magnet will fit through the baffle most people wouldn't care.

A multimeter will work to check continuity. That won't tell you if the voicecoil is rubbing so a listening test would need to be done for that. (That's probably too much to ask for though.)

 

[alteclipsch]

Just found a listing on Craigslist for a pair of tweeters. $50 for the pair. Is that reasonable? (Edit: sorry, guess we can't talk about money here.) I'm seeing what I think is honey-colored adhesive, so maybe they're the model 5 version? From what I'm reading (here) the model 5 version might actually be better, so it might not matter which?

Those drivers have been on CL for at least 2 years. It'll be interesting to hear if they're decent tweeters (if they actually exist).

 

[Trygve]

Those drivers have been on CL for at least 2 years. It'll be interesting to hear if they're decent tweeters (if they actually exist).

Alas, I have a lot of distractions at home. I called a few times, didn't get through, and now they've disappeared. We'll never know!

 

[alteclipsch]

Alas, I have a lot of distractions at home. I called a few times, didn't get through, and now they've disappeared. We'll never know!

They're on there this morning, but I doubt they really exist. Esp since you had no response.

 

[Trygve]

Long gap here, but thought I'd close the loop on this exploration. Never did hear back about those Craigslist tweeters, but I found another pair for somewhat less than most, put them in, hooked them up, and things sound great! Unfortunately I don't have a lot to compare with, but we're enjoying them. Maybe that's actually fortunate - I don't yet know what I'm missing.

After having to take them back apart to wire up the new tweeters, I would not recommend the insulation rope caulk that I photographed above. Much too difficult to unstick the woofers from the cabinet. I switched back to the (original, I think) thin foam gaskets as I didn't see a difference in the seal with the caulk anyways.

Thanks for all the advice!