adam2434

Installed the new Klipsch Ti tweeter diaphragms today after cleaning out the old ferrofluid and adding new. BTW, the old ferrofluid was still very much a liquid and absorbed into the paper cleaning strips that came with the ferrofluid. Just out of curiosity, I did a crude frequency vs. SPL test on the original poly vs. new Klipsch Ti on one of the tweeters. All the parameters were consistent for both tests (same tweeter and meter position, same test tones, same source and amp volume levels). See the attached images for the test set up and a plot of the results. The differences between the 2 diaphragms surprised me. I mean my testing was crude, but it was consistent. 🙂 I was kind of hoping that the Ti would be flatter than the original poly, but the poly is actually more linear in this test. Any thoughts on how to interpret my test results? Have not had a chance to listen to the new Ti diaphragms yet - will do that later today and tomorrow.

I was finally able to order 2 Ti tweeter diaphragms from Klipsch today (127123 - K-792/103-TI DIAPH. KIT ) for $69 total shipped. The customer service rep did not ask for serial numbers. Also ordered some ferrofluid from Parts Express. Will report back after I get them into the KLF-20 tweeters.

Well, it's been a week and I have not heard anything from Klipsch CS on the availability and price for a K-79-K tweeter Ti diaphragm. Called the 800 number and the voice directs you to create an on-line ticket (which I did a week ago), then the call terminates with no option to talk to anyone. That is pretty sad. Does Klipsch basically not have customer support/service any longer?

I sent an on-line support request last week asking for the K-79-K replacement tweeter diaphragm availability, part number, cost, and material of construction (titanium?) Have not heard back yet. Off-hand, does anyone know the Klipsch part number for the K-79-K replacement tweeter diaphragm?

Hi, yes, I have listened to the tweeters and mids with a paper towel roll. I don't necessarily think either speaker has a problem per se. I really just think they might just emphasize some frequencies that come off as sibilant and a bit harsh to me, compared to other speakers I own. BTW, I've owned and sold-off some other Klipsch models (and other brands too) that I also found to be sibilant and harsh to my ears. The RP-280F and RB-81 II are 2 examples. But, I don't find the Forte I and RF-7 III I currently own to be sibilant or harsh. Thanks to all for the input.

Yeah, I've read some of his posts on this stock poly diaphragm and how much he dislikes it. As for the crossovers, I replaced the single electrolytic in the woofer circuit, but left the 3 mylar caps alone in the mid and tweeter circuits. Other than reinforcing the interior cabinet joints with construction adhesive, adding front-to-back bracing, and replacing that capacitor (those 3 things are already completed), that's about as far as I want to take these speakers, other than possibly new tweeter diaphragms. Really just want to get them physically and electrically sound, and sounding good for when I give them to my son.

OK, that's easy enough to try with a vacuum. Like 24 years of the previous owner's dust in the phase plug. Can those particles cause the tweeter to sound more sibilant and edgy, you think?

Do you think Klipsch titanium diaphragms for the K-79-K in the KLF-20 would tame some of the sibilance a sharpness I'm hearing at times with the stock diaphragms, which I believe are poly? If so, while I'm at it, I could clean the VC gap and add new ferrofluid, if that's advisable.

Huh? In the first post, I asked if anyone else noticed sibilance and sharpness on their KLF-20s and whether new diaphragms (like the Crites Ti) would tame this. There have not been any "yes" and "yes" replies in this thread. If someone replied saying they also found them sibilant and sharp and that new diaphragms improved this, I would be all over it and would be asking what type of diaphragm they installed.

Does this mean you think what I'm hearing is due to faulty tweeters? As I said originally, I'm totally open to new tweeter diaphragms. I just got these KLF-20s a couple weeks ago, and I have no idea if they were abused by the previous owner. I can say that all the drivers "work" and that the cabinets are in good shape.

Hey, can you tell anything from these pics? I'm thinking they are probably the stock polymer diaphragms...I think I see a black shiny dome through the phase plug, but not 100%.

It’s not a file quality issue. It’s a difference in the way the KLF-20 sound (more sibilant and more edgy) with the same content vs. other speakers I currently own, including other Klipsch (RF-7 III and Forte I). A couple examples: On the Eagles “Hell Freezes Over” DVD’s PCM track (a very good recording, IMO, and one that I’ve listened to 100’s of times, and use to evaluate systems), I notice more sibilance and pronounced “s”, “t”, and “ch” sounds. Also, some of the electric guitar parts have a more shrill/edgy sound. Watching TV programs, dialog also has more sibilance and pronounced “s”, “t”, and “ch” sounds. This is not a big deal, but if there was a quick and inexpensive way to improve it (like new tweeter diaphragms), I’d probably go for it. I plan to give these KLF-20’s to my son and I expect that he would be happy with them regardless.

After working on and finally listening to some newly-acquired KLF-20’s, I have found that they have some pronounced and annoying sibilance (that sharp hissy sound with certain consonants) and sharpness/edginess on certain instruments. Sibilance can be in the 5-10 kHz range. I don’t have this complaint on my RF-7 III’s and Forte I’s. Anyone else notice this with KLF-20’s? Would the Crites Ti tweeter diaphragms tame this sibilance and sharpness I’m hearing?

Yeah, already did that and they sound fine. Honestly, I did not listen to them very much before I started working on them (I just got them a couple weeks ago). Basically, I just wanted to get them in good shape and ready for another 25 years of service for when I give them to our son for his man cave someday. Thanks for the "lead" on the potential lead issue. That led me to the idea of resoldering the spade tabs, which apparently fixed the issue.

Well son of a gun - I think I fixed the bad tweeter! I reflowed the solder and added a bit more to the spade tabs, and the bad tweeter works now. Both tweeters measure exactly the same (9.1 Ohms) across the terminals, using my cheap multi-meter. For further confirmation, I ran test tones from 5,000 to 12,000 Hz with both tweeters in the exact same place relative to my Radio Shack digital SPL meter. There are some significant differences between the tweeters, but I don't know is this is typical or indicates an issue with one of the tweeters. The results are below. Any thoughts on this? Frequency Good Tweeter SPL (dB) Bad/fixed Tweeter SPL (dB) 5,000 Hz 84 81 6,000 Hz 85 85 7,000 Hz 85 84 8,000 Hz 81 79 9,000 Hz 79 79 10,000 Hz 75 75 11,000 Hz 69 68 12,000 Hz 67 67

Interesting - I looked at the wires and solder on the spades under magnification and I can't see any break in the wires or anything else amiss. The spades are solidly mounted too - don't move if I try to wiggle them. I could try to reflow the solder on the spades for kicks - can't hurt anything since the tweeter is dead anyway. I've read that the stock tweeter diaphragm on the KLF-20 is a shiny black polymer dome. That Simply Speakers diaphragm has a treated fabric dome per their description. They are cheap enough that I can easily give those a try, but I am also open to other options like a Klipsch or Crites diaphragm.

So, Klipsch sells a replacement diaphragm that works specifically with the K-79-K tweeter in the KLF-20? If so, happen to know the part number for that? I also sent Crites an email with some questions on their titanium diaphragm - waiting to hear back from them.

I did not take the tweeter apart, but the bad one has no resistance value across the terminals. The working tweeter measures around 9 Ohms across the terminals.

So, I’ve been working on a pair of newly-acquired KLF-20 (reinforced all interior cabinet joints with heavy construction adhesive, added front-to-back braces, replaced electrolytic cap in woofer circuit) and got the speakers put back together yesterday. Fired them up yesterday and one tweeter is completely dead. I removed the dead tweeter and tested it by itself with a 7000 Hz test tone and there is zero output. I don’t know how a tweeter could die from simply removing it and reinstalling it in the cabinet. I’m a bit dumfounded on this. How could this happen? So, I guess the diaphragm went bad somehow and I’ll replace the diaphragms in both tweeters so they match. Simply Speakers has fabric and titanium replacement diaphragms for the K-79-K tweeter (links below). https://www.amazon.com/Klipsch-Replacement-Titanium-Speaker-Diaphragm/dp/B00DX7DXHE https://www.amazon.com/Klipsch-Tweeter-Diaphragm-127103-others/dp/B00DX7DSFQ/ref=pd_lpo_2?pd_rd_i=B00DX7DSFQ&psc=1 I think Crites also has a titanium diaphragm that works in the K-79-K tweeter. Any advantages to any of these diaphragm options? Also, I am curious in general about how a replacement diaphragm could change the frequency response or sensitivity of the tweeter vs. the original diaphragm. I mean the replacement diaphragms are different materials and the domes are probably different weights vs. the original. Wouldn’t this impact how the tweeter functions in terms of frequency response and sensitivity?

Yeah, original crossovers. I am actually going to replace the 80 uf electrolytic cap in the woofer circuit and leave the other 3 Mylar caps alone in the midrange and tweeter circuits. Also going to redo the gasket tape on all the drivers. The caps and gasket tape are already on order from Parts Express. BTW, I pulled all the drivers and crossover from 1 of the speakers and glued the interior front and back baffle joints with PL Premium 3X. Went heavy with it and used two 10 oz tubes on 1 speaker. Surprisingly, I was able to use a caulk gun for all of it, with some fancy maneuvering, including my head in the woofer holes at times, lol. I also glued in front to back braces (1" x 3" poplar) and crossed them with and glued them to the existing 2 side to side braces. So now there are 2 "T" braces. If I have time, I'll start on the other speaker tomorrow. Plan to give these KLF-20's to my son, so want to get them in good shape and ready for the next ~25 years of service for when he moves out someday.

Did some more bass heavy music testing on the KLF-20's and could not detect any panel vibration or rattling. However, the bass output level is lighter than I would expect for such large speakers with dual 10" woofers. Also, the woofers don't have as much movement/excursion as I would expect when the volume is pushed. Not sure if this is normal. I was using a pretty beefy amp (Rotel RB-1582 at 200 watts/channel). As a side comment, I found that PL Premium 3X also comes in a 4 oz squeeze tube, which could make application easier in the areas a caulk gun can't be reached for interior baffle gluing.

Yeah, I can see why you would want to go heavy with the adhesive - because it is really acting more like a corner bracket than a joint surface bond. For a front to back brace, I'll have to see where there is real estate, but I'm thinking maybe gluing on a 1"x1" cleat to the front and back, then gluing a 1"x3" brace to the cleats. While I'm at it and the drivers are out, I'd probably also re-cap the crossover - at least any electrolytics. I've re-capped multiple speakers, including a pair of Forte 1.

Sounds like a good rainy day project. After removing the drivers, are folks able to maneuver a standard caulk gun inside the cabinet to apply construction adhesive (like PL Premium) to the front and rear baffle joints?

Folks, thanks for the input. From what I gather, there is no way of knowing whether a specific KLF speaker will have the loose baffle issue based on production date, melamine vs. MDF interior, or any other definitive production factor. Darn, I was hoping there was a way to "detective" this issue, but ok, guess not. 🙂 I will do some more testing on my newly-acquired pair of KLF-20 to see if I detect loose baffles. First round of testing did not show any signs.

So the bad melamine-specific glue highlighted in the attached post was not the problem? I have read about this bad melamine-specific glue in a few places.