Starting to mod KLF-20 cabinet & crossover

I'm finally starting to get to my KLF-20s and I plan to do many of the things that SET12 has done to his Fortes and then some. I want to begin with the cabinet, then go to the crossover.
First, I'm going to remove all the drivers and reinforce the cabinet by Gorilla Glueing in some extra bracing from front to back and from side to side. I'm also going to glue in several 1 1/2" wide triangular wedge shaped pieces up the sides for extra ridgidity. I'll do that up all four corners of each cabinet.
On a previous Tangent 5000 rebuild I did I had glued and stapled 1/2" carpet pad inside the back and sides of the cabinet as well as the top, bottom, and bracing. That cabinet was totally dead in sound. When you slapped the side of the cabinet all you would hear was your hand hitting the surface. Before the bracing and pad installation it sounded like a bongo drum. The finished Tangent speaker was a whole different beast from the stock 5000. Soooo much better and I only used mediocre parts to upgrade the crossover. With the low quality of the stock crossover parts it won't take much to improve many models of Klipsch speakers in the crossover category.
I don't know if I'll do the pad installation, but I'm thinking of tossing the cheesey foam pad and installing poly fill throughout the entire cabinet. Anyone done this to their Klipsches?
Question for SET12 - How are your individual drivers connected to your outboard crossover? Do you have two binding posts (-&+) for each driver on the back of your speaker?
I guess that's all I'll post for now. I'll include more as I progress through this hefty project. This is going to take some time and some information from this forum and members, but from what I've read, it will totally be worth it.

Larry

Larry: sounds like a great project. The KLF 20 is a speaker worthy of your effort and will reward you I am sure. Don't forget to stiffen the top and the bottom. Remember that in a reflex cabinet the volume of the cabinet has to be able to resonate to drive the reflex vents so don't fill the cavity with poly fill. If you want to add damping keep it on the wall of the cabinet. Good luck and keep us posted. Best regards Moray James.

Top & bottom too.......

I planned to reinforce the top & bottom with the the triangular wedges as I had done to the Tangent speakers. The problem with the Tangents was that they had come unglued, so I reglued the panels with the Gorilla type polyurethane glue and added the wedges for additional ridgidity.
I haven't decided yet, but I still may add the carpet padding. Instead of the Klipsch foam pad I may line the wall with a thick batting of polyester over top of the padding. I'm kinda thinking out loud here on the forum so that I can possibly get some better or additional ideas from forum members. Actually, not filling the entire cabinet with poly fill seems like a better idea since it would cost a lot for all that poly fill.....the cabinets are fairly large.
I have considered making a sort of grate across the top of the inside of the cabinet with the wodden bracing so that I could fill the area around the midrange and tweeter with poly fill. The cabinet would still be using the air space, but the woofer's resonances on the plastic horns might be lessened. I noticed a similar thing done on a pair of Von Schweikert speakers I just finished upgrading. Actually, the VS speakers had the bass compartment filled with polyfill and there was an empty section in the center of the speaker cabinet where it was vented out the back. I'm listening to those speakers now and they're sounding great. Anyway, I'm still in the planning & gathering parts stage, so your input is greatly appreciated.
BTW, I already have the Duelund capacitors custom made for the midrange and the Duelund resistors. I also bought a large spool of 10 gauge magnet wire and plan to wind my own inductors. I also have the large film caps to replace the lytics in the woofer's circuit. I have some Russian PIOs for the tweeter which are supposed to be made from copper foil. I still have a few things to buy for the crossover, but playing with the outboard X-over will be a lot of fun during that part of the process.
I'm going to get the glue and bracing today. That's all for now.

Larry

The 5/8" thick fiberglass with vinyl cover ceiling tiles 2'x4' you find at hardware centre's is excellent for lining the inside cabinet walls. Either peel the vinyl off or just glue that side to the cabinet wall. The fiberglass is dense and has a wide band of absorption and works very well. Cheaper than buying actual high density acoustic fiberglass sheet. Sounds like you are going to have a great set of speakers when you are done. I think your idea of using 45 plates to reinforce is a good one as it also ties the panels together and distributes energy in two different directions. Keep us posted. Best regards Moray James.

idadude said:

Question for SET12 - How are your individual drivers connected to your outboard crossover? Do you have two binding posts (-&+) for each driver on the back of your speaker?
I guess that's all I'll post for now. I'll include more as I progress through this hefty project. This is going to take some time and some information from this forum and members, but from what I've read, it will totally be worth it.

Larry

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Haven't heard from you in a while Larry, It should be an interesting build.

To answer your question, yes I have 3 pairs of 5 way binding posts on the back of my Fortes and 4 pairs of 5 way binding posts on each of the Fortes networks. all total 28 5 way binding posts I use the AudioQuest 5-way binding post wrench to do my wrenching with.

As to interior cabinet bracing no I haven't really done anything there I have another project of installing Brass inserts for all the drivers with brass bolts. I do use Still Points with great success 3 on each speaker very expensive. I have a Maple Shade Brass Weight on the top of each speaker to quell resonance not that I notice a great deal because I have such a huge sound stage I guess and the fact that the Forte uses a passive. I have a friend with some Tannoy Golds that have some redone cabinets that I have heard a lot of cabinet resonance from. But I'll tell you they make my Fortes seem very,very tame by comparison. I'm sure doing more with my cabinets would yield more, but there is so much good going on with the music I'm not bothered at all. But if I had my buddies Tannoy's I'd be working on them as no doubt we all have our limits.

Was it worth it?

I wouldn't trade them even for a pair of newer upper end Klipsch because in all likelihood I couldn't live with any stock Klipsch networks.

SET12

SET12, if you ever get bored and are looking for another improvement to do to the Fortes, you should get another pair of Fortes to experiment with. Keep your stock cabinets an then set up the second pair with modified / reinforced / deadened cabinets (but identical driverwise & electrically) and listen to hear the differences between the two. You could just switch the leads from your crossover from one speaker's hookups to the next.
Yeah, hah-hah, that's easy for me to say. It would take a lot of time and money and you're probably pretty satisfied and comfortable with what you have now.....I would be. I still bet you could 'hear' some cabinet improvements.
I went to buy the polyurethane glue and it is way expensive. 16 ounces of Gorilla glue is about $20 and I haven't found the Elmers poly glue I used last time. I believe Elmers is much cheaper and it works as well as the Gorilla type. I'll check some department stores when I'm in town next week. I'll see if I can pick up some new carpet padding scraps from my old job too while I'm at it.
Inside my Tangents I built a crossbrace under the midhorn driver so that I could have it supported by the bracing which had a couple layers of the heavy foam padding wrapped around it. It seemed that the mid driver could be vibrating out on the end of that plastic horn. I may do that on the KLF-20 too.
I'll definitely have bracing from the front panel to the back between the two woofers and between the top woofer and squawker. Klipsch didn't use the thickest MDF on their cabinets, so the bracing should help make up for that. On my Von Schweikerts the MDF is at least 1 1/2" thick where the 10" woofer is mounted and the bracing inside is massive. You definitely do not hear the cabinets on the VS speakers. When I begin to do the work I'll post some pics. I'd like to mount the drivers with those brass machine screws & inserts too. Where did you get them?
The plan is to get the cabinets done first, then put together the outboard crossovers. I have those screw terminal blocks as you do on your x-over and I may start out as totally stock and change out one part at a time (actually, two at a time since for stereo) and listen for the differences. It will be similar to the fun I used to have when I began tube rolling, but it will be with crossover parts. I'm curious as to how many night and day differences I'll hear as I do that.
As a friend of mine told me concerning modifications, "Don't try and make a POS sound good. A mediocre sounding unit is usually that way due to its design. Take something that's already good and make it into something great". I think the KLF-20s are an excellent candidate for improvement. I'm wanting to get the cabinets done by July and the crossovers finished (or nearly finished) in/by August.

Larry

Larry: any updates on your KLF 20's? Just checking in. I have a set and am thinking about chopping up the top to physically align the tweeter and mid I figure any loss of cabinet volume can be adjusted for with internal damping. Best regards Moray James.

Larry I helped my friend rebuild a pair of KLF20's that the glue was coming loose on. After we removed all the horns etc and had empty boxs. We used a stiff putty knife and spent several hours removing the back boards. Yes they will come out without breaking them. We used the same glue you posted and we added several 1"X2" braces on all sides so the motor board and the back board had more braces to glue to.We did NOT try to remove the motor board . This was a several day repair for glue to dry and we used weights on the back board when we finally reglued them back on. We did not use any Extra padding inside. He had a new pair that started to come apart while they were in warranty years ago and the local Klipsch Manager came to his house with another new pair and said the quality control problem that had a batch shipped with bad glue was fixed and if these come lose he will replace them. The new pair of 20's are still solid as are the used one's we repaired for his rear surround speakers. I want to follow your upgrades and see how it turns out. They sound Great stock if they are sealed So I can image how thy will sound with upgrades.
Louis

LAB3: that's a great story of incredible customer service and support. Corporate support does not get any better than that.
Larry: one other thing that you might want to consider is to move the reflex ports from the back side of the cabinet to the front side. New holes on the front and plugs on the old holes on the back. That way you don't have to be concerned with proximity to the front wall affecting bass response. The vent tubes have a lip so your hole does not have to be perfect as it will be hidden. Best regards Moray James.

I had a few other projects to complete....

Another slight delay...........I have a good friend that's moving to Kentucky that needs me to rebuild an antique rocker/loveseat, so I've got some staining, finishing, & reglueing to do on that. Then I have another friend that needs me to rebuild his diamond blade rock saw and set it up to self-feed and have an automatic shut-off and make a plexiglass splash shield cover for it. That one will be done during the KLF project, and probably afterwards.
I got all the parts I need plus the Gorilla glue, but it looks like it will be next week before I get started on the KLF-20s. Sorry to leave you guys hanging like that.
I am REALLY liking the capacitor changes I made on a pair of Von Schweikert VR-2000s. I took out all the electrolytics and used film caps instead and removed some of the film caps in the tweeter and midrange and used Russian PIOs and they are sounding very dynamic and smooth (meaning quick & powerful without the brightness they had before). The more I play them, the better they sound. I think I found a set of keepers with these.
I'll try to remember to take before, during, and after pictures of this project. I'm still debating on what to use for the speaker binding posts on the cabinet. I'm wanting to go all copper, but what I've found so far is too huge and expensive. I'd also like to know where SET12 got his brass threaded speaker mounts and screws.
Well, it looks like I just committed myself to start on this at least by next week so you should be hearing from me again soon.

Larry

Getting started....

Well, I finally got to spend a little time with the KLF-20s this evening and got to remove the drivers and crossover. Once I got to look inside I was surprised. These had some side to side bracing. Good for Klipsch! They also didn't sound like a pair of bongos when I slapped them on the side like my Tangent 5000s did. Klipsch did install some foam pad in the upper half of the cabinet, but the lower half was bare.
I will be adding some front to back panel braces and some 90 degree triangular braces in a few places, but not as much as I thought I'd have to. Maybe a little more glue around the stock braces that have gaps around them also.
I included a picture of the stock crossover with a few of the replacement parts. I will use almost all of the spool of 10 gauge wire to make the four inductors to replace the stock ones with. The large black cap will replace the small green electrolytic. That change will not be only a difference in size, but sound. Electrolytics sound bad compared to a film cap. I want to listen to one change at a time and hear the differences.
Anyway, its a start and I'm just working on the cabinets for now. I'll try and keep my progress updated as I go, with pics added.

Larry

Very cool Larry :thmbsp:

As to my brass I still have not installed the hardware its going to be a lot of work I got mine from Fastenal.

If I had to do pick another method, As a friend suggested I might very well try brass T nuts with brass bolts. A heck of a lot easier then the brass insert I have. Still I should look into the T nuts them selves perhaps I can find some that fit my bolts.

BTW where did you pick up your copper wire from?

And yeah, that stock Klipsch network uke:

You should love that Duelund stuff.

Its hard to predict just how much your going to hear on each step and a lot depends on associated electronics as well.

I can use different CDP's, amplifiers, and even a preamps which I don't use and its all very audible. I have stuck amplifiers, CDP's in where I have had lost half the size of the sound stage.

So YMMV considerably. Associated components with a strong foundation will certainly show off the new low frequency Inductor.

Also what are you going to use to measure the inductance with?

SET12

For winding the inductors I have a 'recipe' somewhere which tells me how many turns to wind each inductor. I also bought a digital inductance meter to double check my work. I figure I'll overwind these a few turns and then check with the meter and snip back till I get the desired inductance reading. I'll start with the smaller chokes first to see how close the 'recipe' is to the actual desired results. Also, I picked up the ten pound spool of 10 gauge copper magnet wire from an Ebay seller for $80. That was before the price of copper went way up.
I'll be using an Elekit 6L6 SEP amplifier and an Ah! Njoe Tjoeb tubed CD player with these speakers. I have replaced the coupling caps in the amplifier with Mundorf Silver in Oils and the sound is delightful.
If anyone is interested in the inductor winding website with the winding calculator, just post your request and I'll look it up and put it in this thread, otherwise I'll post it later when I get to the winding procedure. I could check through my receipts to get you the copper wire vendor's email if you'd like and you could check on their current prices.
That's all for now. I'll post more as I make progress with these.

Larry

Winding inductors is one of those projects I would like to get around to someday. I liked the fact that you braced your cabinets first. Damping plastic horns with plastic-clay works well on Klipsch. I much prefer 3 layer foam from Parts Express for ported bass reflex speakers..where chambers are open to each other. Poly fill just doesn't work as well. Won't hurt for you to post inductor info..giving me something else to contemplate.

hotroady.......

We've talked about this before when I was going to take on this project over a year ago. The website for the winding calculator is: http://www.diyaudioandvideo.com/Calculator/Inductor/ I also stated that the North Creek inductors have a 1 1/4" diameter center and a 1 3/4" width. I'll double check and if that's wrong, I'll post the correct info.
I've been working two jobs lately, plus finishing off some other people's stuff, so this project is getting off to a slow start. I may have some time this week, so I"ll post what i get done.

Larry

It always pays to check....

I decided to drop in a set of Titanium tweeter and mid diaphragms into my KLF 20's last night. To my surprise the K79 tweeters were factory shipped with poly tweeter diaphragms. I was under the impression that these had been fitted stock with the phenolic diaphragms one normally finds in a K79 but this is was not the case as mine came from the original owner who never changed them.
The poly diaphragm is a poor performer and really limits the quality of sound produced by this otherwise fine tweeter. So pull your tweeter and check to see what is in there. If you are on a tight budget I would suggest that you at the least upgrade to a phenolic diaphragm, they are available from those who have upgraded to the Titanium units. If you want the best these tweeters can provide then get the Ti units from Bob Crites, they cost $30.00 each plus postage and are excellent. Best regards Moray James.

I checked mine.....

and the tweeters are shiny black poly domes. Yeah, I'll get to those eventually. I finished the furniture refinishing project and they picked it up today. Yay!! Now I just need a little let-up with the two jobs I'm working and I'll get back to these KLFs. What kind of difference do you hear with the titaniums?
I have reconsidered the crossover plan I had and I'll build it with the new parts I have already bought and not waste time with replacing each stock part at a 'one at a time' pace. This will save me a lot of time that I don't seem to have much of lately. Thanks for the info on the domes Moray James.

Larry

They say the older a man get the more frequently he should be checking his tweeters. The Ti tweeter diaphragms sound smoother and more relaxed. They are better behaved than the phenolic diaphragms especially at the top end of their range. The Ti's provide a smooth open effortless quality to the sound. I do however feel the Titanium mid diaphragms bring a bigger bang for the buck even though they cost more they are worth every penny. If you cannot afford the Ti mids then as a stop gap buy a set of Bob's new phenolic mid diaphragms as they are a significant improvement over the stock phenolic units and are a reasonable price.
I should be cracking my KLF 20 cabinets very soon to do much the same as you will be doing. We can compare notes along the way. Best regards Moray James.

Well what do you know?

I just spent the morning with a set of KLF 20 cabinets in the shop. The front baffle on one was 1/3 totally non connected from the top of the cabinet down. took about 6 minutes of tapping with a rubber mallet to extricate the baffle. So good sense tells me to remove the other baffle besides it will be much easier to reinforce the cabinets with the baffles removed. Ok another ten minutes and both baffles are removed. A little testing with the mallet tells me that the back panels are not secure either less than fifteen minutes later I have both rear panels removed. Turns out they were less secure than the front baffles. Its easy to see why the adhesive problem Klipsch had caused such troubles. They applied such little adhesive that there is no room for error. If you tap on the panels from the inside you can hear where they are loose by the sound. Pouring white glue or Gorilla glue into the seams would help a little but would not be a fix to panel vibrations. So I would suggest that you knock out both front and back baffles clean them up and reinstall them with an adhesive which will make a structural bond to melamine. Best regards Moray James.

moray james said:

I just spent the morning with a set of KLF 20 cabinets in the shop. The front baffle on one was 1/3 totally non connected from the top of the cabinet down. took about 6 minutes of tapping with a rubber mallet to extricate the baffle. So good sense tells me to remove the other baffle besides it will be much easier to reinforce the cabinets with the baffles removed. Ok another ten minutes and both baffles are removed. A little testing with the mallet tells me that the back panels are not secure either less than fifteen minutes later I have both rear panels removed. Turns out they were less secure than the front baffles. Its easy to see why the adhesive problem Klipsch had caused such troubles. They applied such little adhesive that there is no room for error. If you tap on the panels from the inside you can hear where they are loose by the sound. Pouring white glue or Gorilla glue into the seams would help a little but would not be a fix to panel vibrations. So I would suggest that you knock out both front and back baffles clean them up and reinstall them with an adhesive which will make a structural bond to melamine. Best regards Moray James.

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Be super easy with front motor board if you are going to remove it. We did one one as it had a rattle in it when you played them hard. Mike's must have had more glue as the rear boards were a PIA to remove without marking them up. Mike did not want to hit the motor board or the rear board with a mallet.
So we did the hard way with stiff putty knives.
Louis