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Crossover upgrades for Forte?


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Are there recommended/suggested upgrades to the Forte crssover network? Has anyone done this, or is there a resource available for getting this done or buying parts to do it? I hear a lot of discussion on upgrading crossovers, and wondering if this is possible/a good idea for Forte's. Thanks!

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Contact DeanG (aka AK-4) he will be able to hook you up. He can review the schematic for the Forte' crossover network and recommend components and provide you a price for the updates. I have one of his custom AA crossovers with the Jensen PIO's in my center La Scala and boy did it ever make a difference. You would most likely have to remove the corssover assemblies and send them to him unless you can handle the removing and soldering and hot gluing yourself. The Forte' is a pain because the crossover board is intergrated into the rear input cup panel.

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Here is the schematic. I'm right in the middle of making the changes myself.

Getting the xover out is not that difficult. The issue is the size of the board. PIOs, Hovlands, Thetas are all pretty big caps, and trying to fit them on the board is near impossible without some bridging effort.

I'm swapping out the caps for the mids and tweeter only with Auricaps. They will fit snugly. Seems like the best bang for the buck to me. I'm also swapping out the one 40 Ohm resistor with a Mills wirewound.

Solen carries inductors with the same values as you would need, but they will also be much, much bigger than the stock ones, and fitting them on the board will be near impossible. The autoformer also can be swapped out with one made by an outfit in Texas. Overall, from what I've read, it seems that swapping out the caps is the most balanced thing to do. I am going to do one speaker at a time, so I can do an A/B compare.

forte22.pdf

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I believe Popbumper is wrestling with the Forte I. I'm not even sure if Klipsch used a PCB with those.

Here are some Forte II's I did. Hovlands are out, but you can use Thetas since they are fatter than they are longer. Sometimes you have to get creative with the PCB's, and you WILL save yourself a lot of trouble if you leave the inductors alone. I used to replace the iron core with an air core, but it really chews up the real estate -- and I'm not convinced of any performance advantages in the LF by making the switch.

Sometimes you end up jumpering -- where you drill a new hole in the board and scrape down to the copper to get a new solder point. This was the case several times with the Forte II and the Thetas. The vertical Theta entailed some risky soldering, as there was no way to heat sink the lead. You really need some practice with the iron to do this kind of thing -- because you have to do it and GET OFF the pad ASAP. Use flux, and make sure you put enough pressure on the lead and pad with the tip of the iron, as this creates faster heat transfer. The most important things are to carefully plan out how you want to do it, pay attention to what you are doing while you're doing it, take your time, and work clean.

I call Auricaps my "just right" cap. They are not as clean sounding as the Theta, but they are worlds better than the Mylars -- and will plug right in without too much trouble. Sometimes the "best" cap isn't the "right" cap -- but that's another story.

download.asp?mode=download&fileID=32246&

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Dean:

Sorry for the delay in response, had a guest in for the weekend and was very busy!

Do you in fact have the schematic for the Forte I, and can you recommend components for it? I see here that there has been discussion regarding the Forte II, but that's not what I have.

Thanks again!!

Popbumper

PS - If I phoned tech support at Klipsch, would they provide a schematic, if you cannot source it? Is this something that they would be willing to share?

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Most people acknowledge that the crossovers for the Forte and Chorus were well designed.

Once you get a hold of the Forte I schematic, where you are likely to see the most improvement is swapping out caps for better quality ones in the mid and tweeter.

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Dean:

Cool, then one more question (OK, two):

1) Are the "sonic benefits" of upgrades over the stock crossovers substantial?

2) Where do I source actual components (companies, web sites - I have heard of Jensen and others), and what types of caps am I looking for (mylar? polystyrene?)

Thanks again!!

Popbumper

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Dean:

OK, here's the skinny on my Forte's - just pulled one of the crossovers and checked it out. The particulars:

1) Everything IS on a circuit board

2) One 5W, 40 ohm 5% resistor (just an FYI)

3) One 47uF 100V non-polarized cap, can type, leads on same end

4) Two capacitors marked "2E155, TAIWAN". No other markings.

5) One capacitor marked "2E105, JAPAN, B605". No other marking.

6) Two inductor coils, no markings (another FYI).

I am unsure of the ratings on the three caps in "4" and "5". Perhaps you can shed light on this.

At any rate, I need TWICE the quantity of caps here to do both speakers. Can you source these for me as you said? Incidentally, I HAVE asked for a schematic - so if you need the info, I should have it in a day or two.

Many thanks!

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Are the coils both iron core?

If I had the boards, I would just measure the caps -- but the schematic will tell you. Forte II is two 2uF and one 1.5uF in each crossover.

We'll wait and see what the schematic says, no problem getting the caps on my next order. Shouldn't be too painful. I think 2uFs are $8 each, and the 1.5s are about the same.

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This is the text from a couple of past posts that I saved:

Original Forte

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 >>> NOT SURE WHERE HE USED THIS - jerohm <<

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

================================================================

Order: Forte II crossover parts

1 speaker

Function Value Technology Mfg ID Price

Woofer Cap 100uF metalized polprop. Solen $24.55

Woofer Cap 10uF metalized polprop. Solen $3.80

Woofer Inductor 2.75mH Air Core Solen $19.95

Mid Cap 1.5uF film/foil polyprop. Hovland $18.30

Tweeter Cap 1 2.0uF film/foil polyprop. Hovland $20.75

Tweeter Cap 2 2.0uF film/foil polyprop. Hovland $20.75

$108.10

total order

Function Value Technology Mfg ID Price # Total

Woofer Cap 100uF metalized polprop. Solen $24.55 2 $49.10

Woofer Cap 10uF metalized polprop. Solen $3.80 2 $7.60

Woofer Inductor 2.75mH Air Core Solen $19.95 2 $39.90

Mid Cap 1.5uF film/foil polyprop. Hovland $18.30 2 $36.60

Tweeter Caps 2.0uF film/foil polyprop. Hovland $20.75 4 $83.00

$216.20

Crossover upgrades:

Did you check-out the posts from aabernathy? They're for the Forte.

I found values for the Forte II, which, I think is what you want.

If you look at the crossover in your speakers, there are 2 2uF caps and a single 1.5uF cap.

I replaced those with Hovland MusiCaps. There is a 110uF non-polar electrolytic.

I replaced that with a 100uF and 10uF Solen polyprop. in parallel.

Finally, there is a 2.75 milliHenry (not micro) iron core inductor,

and I replaced that with a 2.75mH air core by Solen.

I purchased the parts from Madisound at madisound.com, just as aabernathy suggests.

Warning: the MusiCaps are pretty big, the Solen caps are huge and the inductor is

bigger than huge (look at the specs at Madisound.

The resulting sound is absolutely fantastic.

Also, be sure to apply Moretite or DynaMat Extreme to the horns.

These mods will double your enjoyment of these speakers.

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  • 1 year later...

Forte I schematic attached. Replace resistor with 40 ohm Mills from www.percyaudio.com The inductor for the low pass is fine, leave it alone. From my notes: "In a woofers path, the drivers Q is affected by the coils wire gauge, a low Q driver will have its value rise. In a 1st order crossover, the coils Q is critical, not only will the alignment change, but the bass response as well." The tweeter inductor in parallel with the tweeter and resister is already an air core, again -- leave it alone unless you can find a near perfect match in inductance, DCR, and Q. Don't be shy with the adhesive, the inside of a speaker is a hostile environment. Capacitors should not be supported by their leads or mounted in such a way that they will break loose from the boards due to mechanical vibration.

Forte.pdf

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  • 2 years later...
  • 1 year later...

Sorry, I know I'm replying to a post that is almost 6 years old, but if you're willing to indulge me I have a question about the Moretite/Dynamate being applied to the horns. I just acquired some 89 Forte's and plan on rebuilding the crossovers. Do you mean applying that to where the horns are sealed to the enclosure making a more airtite seal? Or do you mean applying it to the shell of the horn to reduce resonance? Thanks, Brian.

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