Update for Forte and Chorus

[aabernathy]

In and effort to tighten the bass on the Fortes, I placed sand in the riser bases and created a new bottom. Some people use spikes, but I have beautiful hardwood floors that I didnt want to mar.

Materials All materials were purchased at a local Home Depot.

1. Clear Silicon for caulking gun

2. 36 - 1 1/2 wood screws

3. 36 ¾ wood screws

4. 7 ½ of oak 2 X 1 wood

5. 2X4X1/4 Red oak plywood (Home Depot lists this as ¼ B-4 Rot Red Oak 2X4 CFP)

6. 20lb bag of horticultural grade sand (playground sand)

Instructions

Note: After reading through instructions please recheck measurements. This was written down from memory.

1. Flip the Fortes over so that the riser bases are facing up and you can see inside them.

2. Cut the 7 ½ of oak wood into eight pieces (Four that are 13 and four that are 8 ½ long)

Use the 1 ½ screws to secure these pieces of wood one at a time into the interior walls of the riser bases making sure that the 2 side is flush against the riser wall. Forte Mods

3. So, looking down into the riser bases you will see the 1 side facing up toward you make sure that this side is flush with the top of the plastic corner braces of the riser base. This is done so that the plywood you are going to use, as a bottom will sit level on both the plastic corner pieces and the rails you have created. You are securing the rails through the 2 sides into the riser base walls.

4. Silicon the interior cracks where the riser base meets the speaker and the riser base corners. Smooth with finger.

5. Cut the plywood to make two pieces that measure 15 X 10 ½. The 2 X 4 plywood will make four of these bottoms, so go buy more Fortes to modify.

6. Fill riser bases with sand and level with a ruler so that the top of the sand is level with the top of the rails and corner joints.

7. Place plywood piece in place and use smaller screws to secure in place. Secure plywood piece into the rails that you have created. This creates a bottom that should be completely level with the Forte riser bottom.

8. If you are a real anal retentive, obsessive compulsive Klipsch freak like me, you can even stain the plywood bottom so that it matches your speaker cabinets - although no one will ever see it.

9. Silicon the cracks between the riser base walls and the plywood bottom to keep the sand from leaking.

10. Let dry. Turn the speakers over and enjoy until the next rainy day when you can tackle the next mod.

[aabernathy]

After finishing the last post, I realized that I did not mention that these mods are all viable for the Forte II and the Chorus series. The only exception to this is the x-over mod, where the values of the caps and inductors would change. I highly recommend calling Klipsch and asking them for the schematic on whichever one of these speakers you have.

The next couple of mods involve opening up the Fortes by removing the passive radiator, woofer, mid horn, tweeter horn, and speaker wire post box from the speaker cabinet. Simply unscrew the Phillips screws that hold these items in place and gently remove. It is easiest to perform all of these mods at the same time, so that you do not have to continuously remove these items.

The first of these mods was to dampen the horns and woofer cages. I used rope caulk (mortite) on the tweeter horn and sqwuacker horn. On the woofer and passive radiator cages I used dynamat.

It is my belief that whatever speaker cable you use, especially if you use higher end speaker cables, that you should replace the internal factory wiring from the x-overs to the drivers with that wire. This holds truer on the older Klipsch models. I use silver sonic Q-10 from my amp, so inside the speaker I ran silver sonic T-14 to the mid and tweeter and I used Q-10 to the woofer. I also soldered these wires in place using a silver solder from Welborne Labs. There are wire harnesses on the sides of the cabinet that can be used to restrain the wires and prevent them from slapping the cabinet.

The last and final mod to my Fortes was to replace the caps and inductors on the x-over. The parts cost $108 per speaker. It is important that you not be overwhelmed by this step. I knew very little about soldering or x-overs, but it really was not that difficult. Much credit must be given to Al Klappenberger, who over the course of time has answered many of my questions and after much experimentation had already comprised a magical mix of caps and inductors for his AlK networks. I simply borrowed his selections and applied them to my speakers. For the Forte these are:

From Madisound at madisound.com

One-1uf Hovland cap

Two-1.5uf Hovland caps

From North Creek at northcreekmusic.com

One-1uf Harmony Bypass cap

From Solen at solen.ca

One-3mh 10 gauge air core litz wire inductor part # 103.0

One-.16mh 14 gauge standard wire inductor part # S14.16

One-47uf Solen Fast cap part # PA4700

The difficulty with the x-over mod for the Forte comes from the fact that the inductors are too large to fit on the area where the old x-over was mounted (the back of the speaker terminal posts). Therefore, you need to cut a new board that will fit down into the speaker case right behind the old x-over. I cut one that was 4 X 8. Take a look at Als at www.web-span.com/alk/klipsch.html. The screw down posts and barrier block if you choose to use them can be purchased at Radio Shack. Essentially all you are doing is recreating the x-over on the back of the Forte terminal post onto your board. You will have to borrow the autotransformer from the old network. The Harmony bypass cap is to be used in parallel with the Solen Fast Cap. Al recommends using a silicon glue to attach the caps with flexible leads to the board, so that they will not vibrate. I used wire harnesses on the inductors that secured though pre-drilled holes in the board. Once you have completed your new network, according to the schematic and simply by glancing how the old one was put together, you will need to mount it inside the cabinet. I used L brackets and screws. Next, solder you internal speaker wires in place onto the network. You will need to remove the old components from the speaker terminal posts back and solder speaker wire from the back of the posts to the network. Of course, I used silver Sonic Q-10 for this. Finally, screw everything back in place, pick your favorite song and get ready to be blown away. Remember, there is a little burn in time involved.

If you need the values for the Forte II, I have those as well, but I believe it is in your best interest to ask Klipsch for the schematic.

[Rich Carroll]

Drew-- Thanks for posting these. As per our emails, I am enjoying my newly purchased Fortes, but am eager to do the mods and hear the differences.

In fact, I am on my out the door to Home Depot right now to get the sand filled bases material. I think I will do the mods 1 at a time to see the difference that each adds. I know this leads to some repeated taking apart, but it will be worth it to hear the gains from each mod.

I will check out Al's material on the x-overs. He lives close enough for me to visit and he and I have chatted by email re my Heresys.

Thanks again for the posts.

Regards,

Rich

[aabernathy]

Rich,

Make sure to let us know what you think about each one of those mods. If I lived close to Al, the poor guy probably couldn't get rid of me. Best of luck to you.

[Cruzer]

I live too far, Germany, but will eagerly wait for you guys to let us know the final outcome, good luck!!

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Cruzer

[Rich Carroll]

Drew et. al.-- I haven't posted for a while because of several things that have kept me away from the speaker mods and the computer. But hopefully in the near future I will be getting the sand bases completed and the mortite on the horns.

Rich

[cn1790]

Rich, Did you ever do these mods? If so what did you think. In curious as to the before and after sounds. -tim

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On 6/8/2001 5:20:00 PM Rich Carroll wrote:

Drew et. al.-- I haven't posted for a while because of several things that have kept me away from the speaker mods and the computer. But hopefully in the near future I will be getting the sand bases completed and the mortite on the horns.

Rich

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[Strabo]

Thanks for bringing back this thread. Oddly, I popped the hood (radiator) on my Forte 2's this morning just before checking in here. Never had them open before and now I have all kinds of questions.

I was looking into doing some of these mods too. My main reason for opening them today was to see if I could spend the afternoon watching football and adding some rope caulk.

I've never seen the horn on the original Forte's but on the 2's the mid is made of a ribed plastic. I'm curious how someone would caulk these. I've imagined that I could remove the mids and tweets and just wrap them up, but with the ribs running length-wise on those horns, how does one do it?

After seeing them in person, I was thinking dynomat would be the a better treatment since I could cut it to right sizes to fit in all the nook and crany's on the outside of the horns.

Some suggestions here would be helpful.

My next plan was to Dynomat the support spiders on the woofer and radiator which was mentioned above. After taking out the passive I believe that it would benifit the most as it rings pretty good without the magnet on the end to stiffin it up. But as long as I am in there I might as well do the woofer too.

I am also wondering if anyone has dynomated the inside walls of the cabinet itself? Would it change the cabinate volume too much? I don't want to change the F's but I do want to tighten things up a bit.

While I was in there I also took a look at the crossover (took a couple of pictures too). I know very little about this stuff but one of the caps is rated at +/-10%. That shocked me (figuratively). Is it crazy for me to think about changing it to something with closer tolerances while keeping the specs the same?

[cn1790]

Strabo, I pressed the rope caulk into the valleys of the ribs, over ribs into the next valley and so. It did make a big difference. The WAF approval factor was quite high on this one followed by putting in speaker spikes which was also what high on the WAF scale. I used 1.5 roles of rope caulk per for each Forte. Also I did not bother breaking it into small strips. It's like modeling clay and it takes some time to do but worth it.

[cn1790]

Aabernathy, are you still pleased with your x-over? I'm considering taking it on as a project but was curious as to your thoughts now that it has been a few years. Any idea what Al's new web site might be? It tried the www.web-span.com/alk/klipsch.html location and received a message saying the site didn't exist anymore.

Thanks,

-tim