Forte (I) crossover caps and other refresh items

[adam2434]

Just picked up a pair of Forte (I) and am thinking that it would be good to replace any electrolytic caps in the crossovers, since they are around 30 years old.

 

From some internet photos and schematics, looks like there is a 47 uF electrolytic in the woofer circuit, but the rest appear to be film caps.

 

Does this sound right?

 

I know there are various levels of Forte crossover upgrades and mods out there, but I'm thinking more along the lines of bringing them back to factory specs, rather than investing in upgrades at this time.

 

 

[willland]

Have you opened them up yet?  Maybe cap replacement already done.  I have a pair of Heresy II's that I have never opened up.  I intend to do that before I order new crossover parts.  Just asking because there are plenty out there that have been renewed and maybe, your pair is one of them.

 

Bill

[adam2434]

Have not opened them up, but they guy I bought them from was the original owner and did not seem like the type that would replace the caps.  In fact, I mentioned to him that the electrolytics would likely need to be replaced and I don't think he knew what I was talking about.  

[willland]

3 minutes ago, adam2434 said:

Have not opened them up, but they guy I bought them from was the original owner and did not seem like the type that would replace the caps.  In fact, I mentioned to him that the electrolytics would likely need to be replaced and I don't think he knew what I was talking about.  

Good to know.  Sure helps to know the original owner to determine speaker history.

 

Bill

[adam2434]

Want to expand this topic beyond crossover caps to include other possible refresh items that could bring them back to original performance.

 

For example, I read that the grill peg inserts and woofer/PR gaskets can leak air.  Several of the grill peg inserts come out of the motorboard attached to the grill pegs.  Should I consider gluing the grill peg inserts and replacing the woofer/PR gaskets?

 

Interestingly, all but a couple of the woofer, PR, and horn screws were very tight and could not be tightened further, although the terminal cups could be tightened a bit.  Generally, I have found that both new and used speakers could use a bit of screw tightening.  The only other speakers I've owned that were super tight from the start are my RF-7 II's.  Perhaps Klipsch has the driver torque set optimally in Hope.  

 

 

[oldred]

I have rebuilt at least 4 pair of Forte 1's. Yes every pair had at least 1 of the grill peg retainers that pulled out of the holes. Generally I usually remove all of them and glue them in to keep them in place. Elmer's glue. As far a the tightness of the drivers. Because Klipsch doesn't use any threaded inserts the screw holes have a tendency to strip or not tighten properly.

The standard glue and broken tooth picks in the screw hole work to make drivers seal properly on the gaskets. I generally install the passives last in case there any tooth pick pieces that fall into the cabinet. I have rarly found any passive screws holes stripped. And when they were I would do the tooth pic/glue fix and then put a piece of masking tape to over the back side of that hole (inside the cabinet) to minimize any pieces fulling into the cabinet.

 

George,

[001]

These speakers have an electrolytic cap for the woofer roll off part, the others are film, but due to age they can all fall out of spec.  I had some forte 2 that the mid & tweets sounded like crap in one speaker & not quite as bad in the other, at first I thought it was bad diaphrams but when I tested them with a meter they were within spec. So I took a chance & replaced the caps with some daytons from parts express, hooked them all back up & BAM, night & day difference.  They were a completely different speaker, full bass & crisp clear mids & tweets. 

 

IMO, you do not need to buy the expensive caps, & many of them are physically larger & require a seperate board to mount.  The improvement is from replacing the aged possibly out of spec cheap caps with new & better quality caps.  For the average person with average gear, I highly doubt the human ear can tell the difference between a quality poly cap that costs a few bucks vs ones that cost 5-10x more.  Granted, for very expensive top of the line speakers & gear like tubes or SS amps hat cost thousands of dollars etc then yes a more expensive cap may be in order, but for fortes & other  "mid-fi" speakers & gear, you will be very happy with a decent cheaper cap like the daytons.  & getting the same values as the originals will keep the sound exactly as klipsch designed, just better quality parts. The stock caps probably cost pennies each!

 

 

[adam2434]

17 hours ago, oldred said:

I have rebuilt at least 4 pair of Forte 1's. Yes every pair had at least 1 of the grill peg retainers that pulled out of the holes. Generally I usually remove all of them and glue them in to keep them in place. Elmer's glue. As far a the tightness of the drivers. Because Klipsch doesn't use any threaded inserts the screw holes have a tendency to strip or not tighten properly.

The standard glue and broken tooth picks in the screw hole work to make drivers seal properly on the gaskets. I generally install the passives last in case there any tooth pick pieces that fall into the cabinet. I have rarly found any passive screws holes stripped. And when they were I would do the tooth pic/glue fix and then put a piece of masking tape to over the back side of that hole (inside the cabinet) to minimize any pieces fulling into the cabinet.

 

George,

Thanks for the input.

 

Elmer's glue, huh?  I thoughts that was only for paper and popsicle sticks.  

 

Regarding the screws, I don't think any are stripped...yet.  They just could not be tightened further.

 

 

 

[adam2434]

4 hours ago, klipschfancf4 said:

These speakers have an electrolytic cap for teh woofer roll off part, the others are film, but due to age they can all fall out of spec.  I had some forte 2 that the mid & tweets sounded like crap in one speaker & not quite as bad in the other, at first I thought it was bad diaphrams but when i tested them with a meter they were within spec. So i took a chance & replaced the caps with some daytons from parts express, hooked them all back up & BAM, night & day difference.  They were a completely different speaker, full bass & crisp clear mids & tweets. 

 

IMO, you do not need to buy the expensive caps, & many of them are physically larger & require a seperate board to mount.  The improvement is from replacing the aged possibly out of spec cheap caps with new & better quality caps.  For the average person with average gear, I highly doubt the human ear can tell the difference between a quality poly cap that costs a few bucks vs ones that cost 5-10x more.  Granted, for very expensive top of the line speakers & gear like tubes or $5k-$10k SS amps etc then yes a more expensive cap may be in order, but for fortes & other  "mid-fi" speakers & gear, you will be very happy with a decent cheaper cap like the daytons.  & getting the same values as the originals will keep the sound exactly as klipsch designed, just better quality parts. The stock caps probably cost pennies each!

 

 

Interesting...I had always heard that film caps do not deteriorate significantly over time, and therefore would not need to be replaced for the purpose of bringing the speakers back to factory specs.

 

I'm thinking that a 47uF replacement would need to stay electrolytic, as a film cap of that value would be too large for the board.  The other caps are (2) 1.5uF and (1) 1.0uF.  I would think that Dayton film caps would fit on the board in the 1.5 and 1.0uF spots (if I decide to replace the film caps too).

 

By the way, I have used Dayton film caps in the past on a pair of Acoustic Research AR18s that I refoamed and recapped.  The crossover was a single cap on the tweeter - that was an easy crossover refresh.  

 

 

 

 

[001]

I'm far from a cap expert so I can't say either way about those stock film caps, but from what I understand the current poly caps you would use to replace them are of a much higher quality then the stock caps, & they are new.  I think its worth a few bucks to get all new poly caps, like I said the film caps in my fortes were indeed bad, replacing them made the speakers sound like they should.  & yes the 47uf cap would be rather large & expensive & it doesnt need the benefits of a good poly cap.

 

I have used the daytons & a few other similar priced brands in other speakers over the years & have been very happy with all of them.  I'm sure the expensive caps are nice & they do have their place, all comes down to your budget... if you drive a 1985 mustang with 150k miles that you paid $1500 for then $2.50/qt oil is probably fine, but if you drive a new 2016 mustang with 500+ horse power that cost $50k then im sure you want the top of the line $15/qt synthetic oil.  & putting that expensive oil in your old mustang wont make it run any better, just makes your wallet lighter!   

 

[adam2434]

22 hours ago, klipschfancf4 said:

I'm far from a cap expert so I can't say either way about those stock film caps, but from what I understand the current poly caps you would use to replace them are of a much higher quality then the stock caps, & they are new.  I think its worth a few bucks to get all new poly caps, like I said the film caps in my fortes were indeed bad, replacing them made the speakers sound like they should.  & yes the 47uf cap would be rather large & expensive & it doesnt need the benefits of a good poly cap.

 

I have used the daytons & a few other similar priced brands in other speakers over the years & have been very happy with all of them.  I'm sure the expensive caps are nice & they do have their place, all comes down to your budget... if you drive a 1985 mustang with 150k miles that you paid $1500 for then $2.50/qt oil is probably fine, but if you drive a new 2016 mustang with 500+ horse power that cost $50k then im sure you want the top of the line $15/qt synthetic oil.  & putting that expensive oil in your old mustang wont make it run any better, just makes your wallet lighter!   

 

 

Yeah, might as well also replace the 1.0 and 1.5 uF caps with Dayton Precision caps for a couple bucks each.

 

Do all the drivers and horns need to be removed and disconnected in order to replace caps, or is there enough slack in the wires to allow work on the crossover with wires connected to the drivers?

 

Also, any recos on a good radial 47uF electrolytic for the woofer circuit?  Parts express only has a cheap one with +/- 20% tolerance.  I'd be willing to spend a few bucks on better electrolytic with tighter tolerance and better reliability/longevity.

 

 

[djk]

Buy all the caps from Erse, ±5% electrolytics, ±3% Polypropylenes.

 

http://www.erseaudio.com/Products/NonPolarElectrolyticAll/ANP10C-05-47-0-PB

 

http://www.erseaudio.com/Products/PulseXAll/MPX25-03-1-50

[rbrown0678]

  becoming  the owner of a 30 year old vintage speaker ,that I imagine is in good condition even if you paid a great price to put a reletively small investment in them is more than worthwhile. The ear needs to be massage, 

No second guessing as to how much better they might sound, there no need to do it twice which cost more in the end, that anology of the car is good thou I think most people buying a used car would like to detail it, to at least see it looking it's best just make you feel better. 

[adam2434]

2 hours ago, djk said:

Buy all the caps from Erse, ±5% electrolytics, ±3% Polypropylenes.

 

http://www.erseaudio.com/Products/NonPolarElectrolyticAll/ANP10C-05-47-0-PB

 

http://www.erseaudio.com/Products/PulseXAll/MPX25-03-1-50

I was looking at the Erse NPE's earlier this evening but only saw ones with axial leads, whereas the crossover uses a 47 uF NPE with radial leads.  However, the guy in this thread made axial leads work.  http://audiokarma.org/forums/index.php?threads/re-capped-my-fortes.371297/

[adam2434]

Parts Express is only around 30 min away, so I may run up there after work tomorrow to get the following caps, if time allows.

 

47uF NPE with +/- 10% tolerance (better than the typical +/- 20%).  This cap has axial leads, but should still work in the radial holes, based on what others have done.  Interestingly, 2 of the 4 reviews mention using them in Forte's

http://www.parts-express.com/47uf-100v-electrolytic-non-polarized-crossover-capacitor--027-352

 

I will go with these for the film caps:

http://www.parts-express.com/dayton-audio-pmpc-15-15uf-250v-precision-audio-capacitor--027-212

http://www.parts-express.com/dayton-audio-pmpc-10-10uf-250v-precision-audio-capacitor--027-210

 

In the audiokarma thread I linked above, looks like the guy replaced the caps without removing and disconnecting the drivers.  Is this how others have done it?

 

I will also glue the grill pin inserts in the next few days.

 

The PR push test takes about 2 seconds for the woofer to return.  I'll be curious to see if  gluing the grill pin inserts impacts this.  They pull out of the motorboard easily, so there is no way they are air-tight in their current state.  I do not see any old glue on them, so looks like they were just pressure fit by the factory, which is not adequate.

 

Have folks found the need to reglue or reseal the interior cabinet joints?  I've read that folks have done this, but not sure what drove them to do it.  Could they feel air exiting the joints?

[001]

The axial leads are easy to make work, just clip off some of the excess length on the bottom lead to use as extensions, you make small little j hook bends in both ends & solder them together to make the top lead long enough to bend & run down the side of the cap. When done right it mimics the radial caps leads & lets you place the leads into the holes of the board. If you have average or above soldering skills this should be pretty simple to make them work... trying to fit other oversized caps on these small boards is more difficult & simply not needed to get the sound improvement of new caps.

 

You dont need to remove the drivers, with the passive radiator removed just unhook the wires from the terminals & the complete assembly comes out & lets you work on a table or bench.  Mark the wires of course so they go back to the right locations.  

 

Its a good idea to glue in the peg inserts of original fortes, the forte2 uses magnets that dont come out. I would suggest a silicone adhesive type caulk for that, but elmers glue would work too, silicone seals better & doesn't get brittle over time like elmers could. Either will work fine.

 

The cabinets of the fortes, quartet & chorus are built much better than the KLF or KG lines & usually never need reglued, don't think I've heard of any having problems.  But if you want you can always run a bead of a quality wood glue along the seams, gorilla glue works great for this. 

 

& a few other tricks you can do that moray james has mentioned is to wedge a piece of rubber inbetween the back of the mid magnet & the rear panel, it acts as a brace to the big rear board, just enough to put a little pressure on it.  & line the interior part of the mid horn with a dynamat type material to dampen the horn, same with the woofer basket.  & another mod is to add about 2oz of weight with some washers to the rear passive at the center pole, this is supposed to tune the bass down a few hz, some people disagree with this & think it will damage something but I doubt thats the case & have never heard or read of any problems. 

 

good luck on the caps & post some pics when it's done.    

 

 

[adam2434]

2 hours ago, klipschfancf4 said:

You dont need to remove the drivers, with the passive radiator removed just unhook the wires from the terminals & the complete assembly comes out & lets you work on a table or bench.  Mark the wires of course so they go back to the right locations.  

 

In the audiokarma link I posted above, the guy just pulled the terminal cup from the back of the speaker and worked on it without removing the PR.  Am I seeing that right?

[adam2434]

My experience is pretty limited and I'm already struggling with desoldering the leads from the binding posts.  I'm trying to use desolder braid to take up the old solder, and it is just not wicking up the braid.  I've got the Weller set on 4 of 5, so pretty hot I would think.  Feeling pretty dumb and frustrated at the moment.

[001]

5 hours ago, adam2434 said:

In the audiokarma link I posted above, the guy just pulled the terminal cup from the back of the speaker and worked on it without removing the PR.  Am I seeing that right?

 

Yes, I meant to pull the terminal cup, but in order to remove it from the speaker you have to unhook the wires from each driver... looks like he used a little stand to set the cup on with wires still connected. I found it easier to remove it all the way & work comfortably on a table, works either way though.

 

For removing the old caps I found it easier to just grab the cap with some needle nose pliers then touch the solder gun to the spot of solder from the backside & gently pull the cap... it will break free & pull out & should leave a nice open hole to insert the new caps leads.  Then any minor remaining solder will just get re-flowed with the new solder.  It doesnt take much solder at all, just touch the solder to the lead as you heat it & it will flow into the hole & lock it in place, then cut off any excess leads with side cutters.  That desoldering braid is mainly for larger amounts of solder where it needs to be completely removed, for small caps like these you dont really need to wick away the solder.  Also try to be carefull with the gun/heat, you don't want to get the board too hot, might damage the printed circuits, just enough to melt the solder to free the caps, then same for install, just enough time to melt the solder.  Maybe practice soldering the old caps or small pieces of wire to get the feel for how much heat & time is needed.  it's not difficult, just take a little practice & patience.

 

The film caps are axial so the new axial caps will fit pretty easy into place, my tips for adding an extension with "j-hook bends" was mainly for the electrolytic one & it stands up on end. But I suppose it could lay on its side too.  

 

 

[adam2434]

36 minutes ago, klipschfancf4 said:

 

Yes, I meant to pull the terminal cup, but in order to remove it from the speaker you have to unhook the wires from each driver... looks like he used a little stand to set the cup on with wires still connected. I found it easier to remove it all the way & work comfortably on a table, works either way though.

 

For removing the old caps I found it easier to just grab the cap with some needle nose pliers then touch the solder gun to the spot of solder from the backside & gently pull the cap... it will break free & pull out & should leave a nice open hole to insert the new caps leads.  Then any minor remaining solder will just get re-flowed with the new solder.  It doesnt take much solder at all, just touch the solder to the lead as you heat it & it will flow into the hole & lock it in place, then cut off any excess leads with side cutters.  That desoldering braid is mainly for larger amounts of solder where it needs to be completely removed, for small caps like these you dont really need to wick away the solder.  Also try to be carefull with the gun/heat, you don't want to get the board too hot, might damage the printed circuits, just enough to melt the solder to free the caps, then same for install, just enough time to melt the solder.  Maybe practice soldering the old caps or small pieces of wire to get the feel for how much heat & time is needed.  it's not difficult, just take a little practice & patience.

 

The film caps are axial so the new axial caps will fit pretty easy into place, my tips for adding an extension with "j-hook bends" was mainly for the electrolytic one & it stands up on end. But I suppose it could lay on its side too.  

 

 

Thanks for the input.

 

I just finished soldering the first one and I am testing it before adding some hot glue to the new caps and and remounting it to the cabinet.  

 

All 3 drivers are working!

 

The worst part was desoldering the leads from the binding posts.  My guess is that there is so much mass there that is was hard to get the solder to flow into the braid.

 

I removed all the solder from each cap joint with the braid.  Sounds like I did not need to do that based on your input.

 

Now the tricky part is going to be getting the terminal cup back into the cabinet.  If I try to put the top in first, the big inductor at the bottom does not want to go in the cabinet.  Not sure how I got it out of there in the first place.