Help Me Bring My Forte I Speakers to Life!

[MCM_Fan]

Greetings Klipsch fans! I am a long time AK member, but this is my first time posting in the Klipsch Korner sub-forum.

Two days ago, I picked up a pair of Forte I speakers. I got a good deal on them as one woofer and both tweeters appeared dead. Sorting the woofer was easy. One of the leads had come loose. I hooked it back up and had bass.

The tweeters both have bad diaphragms (open circuit). So, my first question for you experienced Klipsch types - what diaphragms are the best bang for the buck? I've read all about the Crites TI tweeter diaphragms. Most love them, but a few seem to prefer the genuine Klipsch phenolic replacements. The Crites TI are more expensive (I believe the most expensive option). I'm trying to get a glimpse of what these are capable on the cheap, but am leaning to going with the Crites TI as the general consensus is they are an upgrade over the originals and worth the cost. Are there any other, less expensive TI replacements worth considering?

I want to get these up and running so I can spend some time listening to them and decide if they will replace either my KEF 104/2 Reference Series speakers in my bedroom system, or my JBL 4301B Control Monitors in my downstairs dedicated vinyl listening system. But, I want to keep the cost down just in case I don't like them better than what I already have. Who knows, I may keep all three and rotate through them whenever I feel like changing things up.

I am experienced crossover builder and recapper. I actually enjoy building/rebuilding crossover networks. I've recapped too many vintage crossovers to remember, and have built, from scratch, some very complex crossover networks for other forum members (including a pair of biampable crossovers for the JBL L300 Summits based on Nelson Pass' design). So, I've looked at the alternatives, specifically the ALK design, as well as the Crites kit. Again, I'm looking for cheap upgrades/improvements in the near term. If I decide these are keepers, I'll probably go all in and build the ALK crossovers.

I've used the Sonicap Gen 1 caps that come in the Crites kit many times and the past and like them. However, I just checked prices and holy crap, they have gotten expensive. So, I am looking at cheaper alternatives. I recently started using the inexpensive Russian surplus K73-16 PETP caps and they are an incredible value. They also are easy to find in the 1uF (mid) and 1.5uF (tweeter) values used in the Forte 1 crossover. BTW, my Forte I speakers are from May 1988, so they have the circuit board crossovers, not the pile of parts of the original Forte I design.

I plan to give these a try, the only question I have is about the voltage ratings. Both values come in 63V and 160V ratings. In the past, I have used the 1uF 63V K73-16 caps in the tweeter circuits of other speakers, and happen to have some on hand. Is the 63V rating sufficient for the 1uF midrange cap in the Forte I crossover, or should I go with the 160V rating to be safe? Same question on the 1.5uF tweeter caps. Is 63V sufficient, or should I go with the 160V rating?

Edit: In addition to the 63V and 160V voltage ratings, the Russian K73-16 caps also come in 100V, 250V and 400V ratings. The latter two seem excessive for a midrange, and especially a tweeter series cap. Maybe go with 100V on the mid and 63V on the tweeter caps as a good compromise between voltage rating and physical size.

Does anyone have a preferred 47uF NPE for the woofer shunt cap? Does it really matter?

Finally, what other cheap mods are available that offer the best return on investment. I'll seal the cabinets, and add braces, and probably add about 2 ounces of weight to the backs of the passive radiators. Anything else I'm missing?

@moray james @SET12

 

[grindstone]

Starting to believe that forums run on images as fuel. Great questions and completely reasonable. And I've never heard a Forte so I'm no help but I'll continue as functional thread-bump. It's my sense that not many JBL-people are Klipsch people and vice-versa.

While awaiting other opinions, everyone seriously needs more info to answer (and in the end, as you know, preferences will vary anyway). K79 expo tweeter or K75 (no fluid)? Have you opened them up or just confirmed the open coils? The wire is beyond fine, but it might be a saveable break on outer turns if you're patient with great lights and magnification. Planning to sell them (and keep close to stock) if you prefer other things better (or maybe work them into what you like)? What might you hope to get from them vs. existing?

You sound well-founded to re-engineer/mod or restore, so that's the question and the choice, right? I think most of us know the choices and have differing opinions about where that balance happens.

If nothing happens here, it's likely you can drum-up some action on the klipsch technical/modifications sub-forum. Get the serial numbers off the labels (or back of cab stamps) before you go there.

If it's me with real uncertainty about keeping them, I get an L-pad and whatever other tweeters over 96dB that I have (and know) and see if it'll dial-in and just run them a good while to better see what you have. XO's are at 800/6k. It's tough finding phenolic tweeters anymore at all, let-alone any with the same directivity. Cheapest decent phenolic I know is the ST-200 Selenium, but that's a 40-deg conical PA bullet so not a long-term option w/o hacking them up if you like it (pretty flat, but needs compensation/EQ lift above 10k). But if you don't have anything else, you could take a $40-50 flier and set them on top for a test. Even a 1" compression driver and one of Moray & Fred's K-tubes out of paper would do for something to sit on top for testing. The EQ you'll have to work-out. Others will likely have better tweeter suggestions. Least pain/fastest is patronizing Michael Crites.

Maybe do nothing--go with me a minute on this. Stick 6(?) ohms across the HF xo terminals and just run what's there. Yes, the xo doesn't "see" the right load and yes it affects the entire speaker, but just go with it. (And yes it's a 4-ohm speaker). If the bottom has potential to you, keep going and start thinking bracing. If your other speakers need more bass and these have it, well that aids the decisions. If nothing else, you can move it around your room and see if you have a placement that'll fly. If not, you avoided something. Most people seem to like Forte bass. If nothing else, please drop a note to update what direction(s) you went.

 

[vinyldavid]

I'll throw my 2 cents in...the Forte I is the only older Klipsch speaker I've ever heard sound acceptable, and I've heard just about everything.

The pair I've listened to over the last 15 years is factory, with no mods.

If I were you, I would fix it "factory" and go on with life.

 

[usedto]

Any "upgrade" you make, you no longer have Fortes.

Why not put them back stock and see what you have? You may like them just the way they are.

 

[lico]

Hey there. I was highly surprised when I stumbled upon some Klipsch Forte 1's I found for free ( 2 or 3 years ago can't remember). 1985 version. It was a lucky day I guess. They all worked and sounded pretty decent as is. Cabs were a mess but that was easy to restore getting back to original and walnut looks fantastic after a bit of restore. I then opted for the Crites crossover upgrade since I found the speaks for free - figured why not, plus get the Ti drivers.

My impressions are the original phenolics are quite decent. You know how it is..... I swapped back and forth a few times I ended up with the Ti. Maybe because I like JBL speakers, it's all personal preference. The originals were mellower but good. I might still have them if you need something PM me.

Andi if you can recap a crossover (have done many myself) would probably just do that, Crites mods are bit over the top with the board and all bit make it easy lol. Depends on cost of entry on what you are looking to get of out the speakers.

Bottom line is my Klipsch Forte 1's are a daily driver in one of my set ups now. I would not trade them for another modern bookshelf or other speaker. They surprised me on sound and will you too once you get them running right.

 

[MCM_Fan]

Thanks to everyone who has responded. I really appreciate your suggestions. I have a few more questions, but first I'd like to respond to some of your specific comments.

K79 expo tweeter or K75 (no fluid)?

I get an L-pad and whatever other tweeters over 96dB that I have (and know) and see if it'll dial-in and just run them a good while to better see what you have.

I have the K75 tweeters, not the K79 expos. I should have mentioned that in my first post.

Hmmm... when I first read your suggestion, I started to think of what other tweeters have on hand, and nothing appropriate jumped to mind, then I remembered I have some B&C DE250 compression drivers, some SEOS12 waveguides and some 8 ohm, 50 watt L-Pads left over from a previously uncompleted project. I could hook these up and mount them on top of the cabinets. I'd have to pad them back quite a bit (108.5 dB), but the 50 watt L-pads should do the trick. That will give me something to play around with while I decide my next steps.

Hey there. I was highly surprised when I stumbled upon some Klipsch Forte 1's I found for free ( 2 or 3 years ago can't remember). 1985 version. It was a lucky day I guess. They all worked and sounded pretty decent as is. Cabs were a mess but that was easy to restore getting back to original and walnut looks fantastic after a bit of restore. I then opted for the Crites crossover upgrade since I found the speaks for free - figured why not, plus get the Ti drivers.

My impressions are the original phenolics are quite decent. You know how it is..... I swapped back and forth a few times I ended up with the Ti. Maybe because I like JBL speakers, it's all personal preference. The originals were mellower but good. I might still have them if you need something PM me.

My cabinets (oak veneer) are in really good shape. So, at this point, the biggest issue is the non-functional tweeters. Since I like my JBLs in my vinyl rig, maybe I will prefer the brighter Crites TI diaphragms over the mellower originals. Hard to say, as I've heard neither. If you still have your originals, I'd love to give them a try. I'll send you a PM. Thanks!

I'll throw my 2 cents in...the Forte I is the only older Klipsch speaker I've ever heard sound acceptable, and I've heard just about everything.

The pair I've listened to over the last 15 years is factory, with no mods.

If I were you, I would fix it "factory" and go on with life.

Any "upgrade" you make, you no longer have Fortes.

Why not put them back stock and see what you have? You may like them just the way they are.

It's interesting that, so far, the originals are winning the poll (only 3 votes but 100% for the original). The thread currently directly above mine (Care and Feeding of Forte I's?), asks the same question and in that thread, most are recommending the Crites TI diaphragms. I guess it really is a matter of personal taste. I may have spoken too soon about the originals being significantly cheaper than the Crites TI diaphragms.

When I do a google search for Klipsch K-75 replacement diaphragms, this is the first item that pops up:

Such a deal, genuine Klipsch factory replacements for $17.95 each deliver to my door! But wait... When I click on the link, here's where it takes me:

Same price, but notice they are no longer Klipsch Factory Repair Diaphragms, they are now Klipsch Style Speaker Diaphragms. Wow, that's a pretty blatant bait and switch - advertise the real deal, but then link to some generic, no name replacements for the same price.

So, if @lico no longer has his original Klipsch diaphragms, does anyone know of a source for the real deal genuine Klipsch Factory Replacement Diaphragms?

 

[usedto]

Since those diaphragms fit so many other speakers, I doubt Klipsch actually manufactured them.

I believe Crites also sells original style as well as titanium.

 

[MCM_Fan]

One more question on the crossovers. For now I'll likely just recap the existing crossovers. That 47uF NPE is now over 33 years old. That's pretty old for an electrolytic capacitor.

In the past, I've used Mundorf E-Cap AC NPEs as woofer shunt caps and have been happy with the results. So, that's an option here, but like most NPEs the Mundorff ECAPs have axial leads. They are also pretty large for electrolytics. I can make that work, but it would be easier to use a radial lead NPE, similar to the original. I found the ELNA RBD series of radial NPE caps while poking around the Parts Connexion site:

They specific mention using them in crossovers and it seems like an easy drop in replacement for the originals. Does anyone have experience with these? I think I'm going to go for it. In addition to having radial leads, they are much less expensive and much smaller than the comparable 47uF Mundorf E-Cap

 

[MCM_Fan]

Since those diaphragms fit so many other speakers, I doubt Klipsch actually manufactured them.

I believe Crites also sells original style as well as titanium.

Yes, what Simply Speakers are selling are definitely NOT genuine Klipsch replacements. That's clear just by looking at the photo. I find it very deceptive for them to advertise factory replacement parts, but when you click on the link, it takes you to generic replacements for the exact same price. It seems like they hope most people won't notice the bait and switch tactic.

 

[DavidF]

Yes, what Simply Speakers are selling are definitely NOT genuine Klipsch replacements. That's clear just by looking at the photo. I find it very deceptive for them to advertise factory replacement parts, but when you click on the link, it takes you to generic replacements for the exact same price. It seems like they hope most people won't notice the bait and switch tactic.

Not sure why you presume it deceptive. They clearly state that the original part is discontinued. You should call Klipsch and ask about "genuine" parts. I suspect that aftermarket is the only way to go after all these years.

I suggest you leave the crossover as-is with the exception of the woofer shunt cap. You could use quality 0.1 uF bypass caps on the OEM poly film caps. This would not require moving to a separate mounting board to accommodate the larger 1 and 1.5 caps. I suppose some have managed to squeeze larger caps into the stock board but I would not have the patience, myself.

I like the idea of listening to them for a while as it makes sense before jumping into modifications beyond that. They may give the JBLs a run for the money. The 4301 is a great little over-achiever but then so is the Forte.

 

[MCM_Fan]

Not sure why you presume it deceptive. They clearly state that the original part is discontinued. You should call Klipsch and ask about "genuine" parts. I suspect that aftermarket is the only way to go after all these years.

This is why I consider it deceptive. This is what they advertise:

They describe it as a factory replacement, but that's not what they are selling and not the part you get when you click on the link. Maybe at one time, that's what they were selling, but it's not anymore and to continue to advertise it as a factory replacement is deceptive.

I suggest you leave the crossover as-is with the exception of the woofer shunt cap. You could use quality 0.1 uF bypass caps on the OEM poly film caps. This would not require moving to a separate mounting board to accommodate the larger 1 and 1.5 caps. I suppose some have managed to squeeze larger caps into the stock board but I would not have the patience, myself.

Other than the NPE bass shunt cap, the originals are polyester/Mylar. I'm curious if replacing them with polypropylene or polyethylene-terephthalate caps will improve the sound. In the required 1.0uF and 1.5uF values polypropylene and polyethylene-terephthalate are small and inexpensive. Not much more expensive than the cost of decent 0.1uF bypass caps (in these sizes/values, the shipping cost is often more than the price of the caps). I have ordered Russian K73-16 caps in the 1.0uF and 1.5uF sizes. The total cost for all six caps, delivered is $12.90. Many folks like these caps, so I figured it was worth 13 bucks to find out for myself. I can do an A/B comparison by modding one crossover, running my system in mono and switching between the modded and unmodded speakers in real time.

Another, even cheaper, option would be to just add 1.0uF and 1.5uF Jantzen Standard Z-Cap polypropylene caps to my Parts Connexion order. Total cost for the six required caps would be $10.44.

Neither of these options would require separate mounting boards. They are easily small enough to fit on the original PCBs.

I like the idea of listening to them for a while as it makes sense before jumping into modifications beyond that. They may give the JBLs a run for the money. The 4301 is a great little over-achiever but then so is the Forte.

The Crites diaphragms will be here well before the capacitors. So, I will start by running them with the stock crossovers. I'll then replace the NPE woofer shunt caps on both crossovers, and the 1.0uF midrange and 1.5uF tweeter caps on one crossover for an A/B comparison to see which I prefer. "Worst case", I prefer the stock crossovers and I have $13 worth of Russian 1.0uF and 1.5uF K73-16 caps to add to my parts drawer.

 

[MCM_Fan]

Just a quick update:

I ordered the Crites Titanium diaphragms. Original Klipsch phenolic diaphragms are not available, so the Crites TI seem like the way to go.

For the crossovers, as mentioned, I am going to try the Russian K73-16 1.0uF and 1.5uF caps in the midrange and tweeter circuits. I am going with 47uF Nichicon DB NPEs in the woofer shunt circuit ("Nichicon’s DB & GB series caps are bipolar electrolytics designed specifically for loudspeaker crossovers."). and Mills MRA-12 resistors. Total cost of everything, including shipping = $100.69. So, a rather low budget rebuild, especially considering the diaphragms alone were $63.

As mentioned the diaphragms will arrive before the crossover parts. That will give me plenty of time to listen to the stock crossovers. Once the parts arrive, I will rebuild one of the crossovers, give it a week or two to burn in and them do a direct A/B comparison between the stock crossover and the modified one.

Thanks everyone for your input.

 

[ZagatoMan]

I'm using the less costly replacement diaphagms in my KG 3.5 and I believe they were an improvement.

I know the KG's are not at the same level as the Forte but I can confirm they work pretty well.

My Crites just arrived in the mail today! So I'll be swapping tweeters around between my 3.2 and 3.5 to see what I like best. So much work to do

 

[MCM_Fan]

I'm using the less costly replacement diaphagms in my KG 3.5 and I believe they were an improvement.

I know the KG's are not at the same level as the Forte but I can confirm they work pretty well.

My Crites just arrived in the mail today! So I'll be swapping tweeters around between my 3.2 and 3.5 to see what I like best. So much work to do

View attachment 2320658

Nice, let us know how you like the Crites TI diaphragms.

Which diaphragms are you referring to as "the less costly replacement" diaphragms. Is that the silk diaphragms from Simply Speakers?

 

[ZagatoMan]

Nice, let us know how you like the Crites TI diaphragms.

Which diaphragms are you referring to as "the less costly replacement" diaphragms. Is that the silk diaphragms from Simply Speakers?

The ones from Simply Speakers.
I'll listen to the Crites for a while and report back.

 

[lightcapture]

Knowing you had made your purchase this post is for anyone else who may be interested.

I have original Forte mkI and love them stock. I see no reason to upgrade. I've seen 2 different x-overs on line for the Forte I, I have the later ones that are the same as Forte II (according to on line photos) if that make a difference (see photo).
Sounded very good w/ a vintage NAD 7225PE receiver I had, as well as with my modern Mystere IA11 tube integrated amp.
My 2¢

My factory x-over


As set up w/ tube amp configuration I was using with them

 

[MCM_Fan]

I've seen 2 different x-overs on line for the Forte I, I have the later ones that are the same as Forte II (according to on line photos) if that make a difference (see photo).

My factory x-over
View attachment 2321466

Same PCB, but not the same crossover. The midrange and passive radiator are different between the Forte I and Forte II, which requires changes to the crossover network. Of the 8 components in the crossovers 6 of them (all four caps, the autoformer and the woofer inductor) are different between the two designs. I just want to mention that so anyone reading this thread in the future doesn't think the Forte I and Forte II crossovers are interchangeable. They are not.

As set up w/ tube amp configuration I was using with them
View attachment 2321471

Very nice! I can't tell for sure from the photo, but it looks like yours have the walnut veneer. Mine are the oak veneer. I'm a sucker for all things walnut, but beggars can't be choosers. At least the cabinets on mine are in excellent condition and just need a couple fresh coats of oil to make them look like new again.

The only other pair of Klipsch speakers I have owned were a pair of walnut KG4s. I don't have a tube amp, but they sounded very nice with a Class A solid state amp. I'm currently running the Forte Is with the same amp.

 

[MCM_Fan]

Thanks to everyone for your input. I have closed the poll. Although "Original Klipsch Phenolic" narrowly edges "Crites TI", after hunting high and low, it appears genuine Klipsch replacements are no longer available. The choices come down to either titanium replacements or the silk dome replacements from Simply Speakers.

I went with the Crites TI replacements and they arrived yesterday. I installed them (using the stock crossovers) and have listened to several of my favorite SACDs. They sound great - very well balanced. I need to play around with the placement a bit, but will continue to listen to them with the stock crossovers until my replacement parts get here from Russia (might be a while) and Canada (should be here by Friday). I'll post another update once I have updated the crossovers.

 

[lightcapture]

Same PCB, but not the same crossover. The midrange and passive radiator are different between the Forte I and Forte II, which requires changes to the crossover network. Of the 8 components in the crossovers 6 of them (all four caps, the autoformer and the woofer inductor) are different between the two designs. I just want to mention that so anyone reading this thread in the future doesn't think the Forte I and Forte II crossovers are interchangeable. They are not.

There is another post on Klipsch Korner directly addressing the xover w/ schematics. The later xover I have in my Forte I (there is an earlier version that uses a different board) is quite similar the Forte II w/ only the cap values slightly different as well as the tweet and mid wired out of phase. Also only the mid driver is different from what I read. Do you know the tweet and mid drivers numbers used with the I and II?

(And yes mine are walnut. Funny I like oak better from the days of owning Altec Lansing that exclusively used oak. I've not seen oak Klipsch so they may not look as good, but walnut is beautiful for sure.

 

[MCM_Fan]

There is another post on Klipsch Korner directly addressing the xover w/ schematics. The later xover I have in my Forte I (there is an earlier version that uses a different board) is quite similar the Forte II w/ only the cap values slightly different as well as the tweet and mid wired out of phase. Also only the mid driver is different from what I read. Do you know the tweet and mid drivers numbers used with the I and II?

Not my photo, but this is the version of the crossover PCB in my Fortes:

Differences (shown in red) between the Forte and the Forte II:

Forte Drivers:
Tweeter = K-75-K
Midrange = K-53-K
Woofer = K-23
Passive Radiator = KD-13 (12")

Forte II Drivers:
Tweeter = K-75-K
Midrange = K-61-K
Woofer = K-25
Passive Radiator = KD-15 (15")

Note: also the horn for the midrange is different (Tractrix horn on Forte II)

Forte Crossover Components:
Tweeter Caps = 1.5uF (x2)
Tweeter Resistor = 40 ohm
Tweeter Inductor = 0.16mH
Midrange Cap = 1.0uF
Midrange Autoformer = T10A
Woofer Shunt Cap = 47uF
Woofer Inductor = 3mH

Forte II Crossover Components:
Tweeter Caps = 2.0uF (x2)
Tweeter Resistor = 40 ohm
Tweeter Inductor = 0.16mH
Midrange Cap = 1.5uF
Midrange Autoformer = T7A
Woofer Shunt Cap = 110uF
Woofer Inductor = 2.75mH

As you can see, there are significant differences between the Forte an Forte II drivers and crossover components. Late Forte crossovers used the same PCBs as Forte II crossovers, but because of significant component differences, the crossovers are not interchangeable between the two models.

(And yes mine are walnut. Funny I like oak better from the days of owning Altec Lansing that exclusively used oak. I've not seen oak Klipsch so they may not look as good, but walnut is beautiful for sure.

The oiled oak finish on my Fortes looks very similar to what I have seen on Altec Model 19s. My finish looks original, and is a little dry. I plan to refresh the finish with a couple coats of Danish oil to make them look like new again.

Regarding oak vs. walnut, walnut is my vibe. Even my lamps are walnut!

I have, however, added an oak turntable to my kit:

So, I'm not opposed to mixing wood types in my pursuit of sonic bliss.