Cody_Mack Posted May 23, 2010 Share Posted May 23, 2010 I have recently noted a distorted sound in one of my Fortes. I first noticed one day when I was listening pretty loud and a much louder bass passage caused the speaker to break up. I first thought something wrong with the woofer. The sound is akin to a surround being damaged. I played it again and put my ear to the front and surprisingly it sounds like it is coming from the mid, or maybe the tweeter. I can’t tell for sure. With my limited technical knowledge I am guessing that a capacitor is failing letting low frequencies get to the driver. Or I suppose it could be something worse like damage to the driver. I have been using the 2A3 amps for the last couple of months. Last night I put the MC250 back in the system and I still hear the distortion at loud volume. I also noticed a distinct loss of resolution compared to the SET amp and I believe also from when I used the MC250 last. I know it is time for a tune-up to the Fortes but have been trying to decide how extensive to go. With all the good stuff I hear about the Fortes, I will probably go all out and spend a few hundred getting them to peak performance. But my immediate concern is; do I have damaged driver(s)? Any way I can test that? I am a little concerned about what some folks repeat over and over; that using a low-powered amp to drive a loudspeaker loud can do damage. Now I have used several low-powered amps to drive each set of my speakers, including the RF-7s that I sold, to very loud levels and seldom to never did I hear any distortion. So, is my SET amp doing damage to the Fortes, or is it simply the caps being out of spec and failing? Rick Quote Link to comment Share on other sites More sharing options...
4tay Posted May 23, 2010 Share Posted May 23, 2010 If the cap went bad (like dried electrolyte) the performance could be degraded. Stock electrolytic caps dry out between 5-20 years. Swap speaker positions, does the problem follow? Yes- speaker problem. No: amp or electronics problem. And the drivers can be ohm'd out to see if it meets spec. Forte tweeter diaphragms are $52 a pair for titanium. Replacement caps start at a few cents for stock quality, $2.68 each for metallized poly Dayton (Bennic) and up from there. "Peak performance" can be had for about $120-$200. Just getting fresh caps (need be nothing exotic) makes a huge difference. Word of warning: if it is determined to be the speaker, (IE the speaker has degraded caps that are the original factory caps) then change them immediately. When an electrolytic cap dries, it degrades. But it's not far from degrade, to shorting out and catastrophic failure. Don't let it go that long! Quote Link to comment Share on other sites More sharing options...
Cody_Mack Posted May 23, 2010 Author Share Posted May 23, 2010 Gonna take them out of the system today and open them up. I have been needing another project to get me off my arse! And the Heresys have been hanging out together, with nothing connected, looking at me with those sad eyes. [:$] I can't wait to get them hooked back up! [] Oh, I noted this statement from another forum: "Typically I find old capacitors that have exploded and failed causing the whole driver circuit to go down! A fair amount of time the old caps drift way out of spec and can endanger the tweeter by allowing to much low feq. to enter into the signal path." Rick Quote Link to comment Share on other sites More sharing options...
4tay Posted May 23, 2010 Share Posted May 23, 2010 Gonna take them out of the system today and open them up. I have been needing another project to get me off my arse! And the Heresys have been hanging out together, with nothing connected, looking at me with those sad eyes. I can't wait to get them hooked back up! Oh, I noted this statement from another forum: "Typically I find old capacitors that have exploded and failed causing the whole driver circuit to go down! A fair amount of time the old caps drift way out of spec and can endanger the tweeter by allowing to much low feq. to enter into the signal path." Rick 1. Good plan! 2. I just lost out on a mega deal: 2 pairs of Heresy' II s sold on CL in Seattle. A- condition. $400/pr or all four for $750. I am just now weeping into my sumatran blend. 3. Exactly..I have been there, seen that. When a cap dielectric dries out, the conductors touch and will blow up violently. It's even worse in a power amp. My Forte II caps were degraded and the sound was duller over time. Quote Link to comment Share on other sites More sharing options...
4tay Posted May 23, 2010 Share Posted May 23, 2010 SAMPLE parts list to restore Forte I's and upgrade: (from partsexpress) Two 100uf Non polarized electrolytics (total about $3.00) Two 10uf NP " piggy backed to make 110uf (Total about $1.15) Two metallized poly 1.5uf caps (about $2.50) Four 2uf metallized poly caps (about $5.00) You really don't need to replace the transformers or coils if you don't want to. And while you are in there: Bob Crites titanium tweeter diaphragms (MUCH better than stock poly!) $55 + $6 S&H. So basically, you will get a boatload more performance for the grand sum of $75. Quote Link to comment Share on other sites More sharing options...
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