BEC

The last time I looked into the lead free solders, there were several negatives to consider. Most or all of these may have been addressed in current lead free solders. One that seems insurmountable is that for re-work, lead is considered to be a contaminant to the lead free joint and that may make the lead free joint unreliable. Seems if that is still true, using lead free for rework where solder with lead was used originally might be unwise. Other negatives were poor wettability requiring use of much more agressive flux. Life of soldering tips decreased to about 20 percent of the life of tips used in lead soldering. And then there is the subject of "tin whiskers". Bell labs found out 50 years ago that they could be prevented by always using some lead mixed with tin.

Send them to Bob he can put some nasty switches in the signal path and AB test them Folks I like Bob also and think he is a stand up guy. I just can not agree with his assessment of the sonic character of capacitors.......... Well, thank you Craig. I would say that if capacitors have any sonic character, that is a character defect.

Wait a minute Dean. I thought you told me that the PIO caps you wanted to use now were near zero ESR? Also I thought the Auricap was very low in ESR. The only thing that indicates poor quality on those is the lame manufacturing process that only allows them hit the capacitance value they are shooting for within 10 percent.

Oh, but you do know something. I think you have that exactly right.

I haven't tried the B&C driver, but the Faital HF200 is very good on the Eliptrac 400 horn.

Hey, don't badmouth the stuff from the 70s. That is back when we could build stuff good enough to go to the moon and back.

Chris, I got the noise sort of acceptable by doing crazy things. Source on an UPS. Two amps across the room from each other but using an extension cord to get them both plugged into the same outlet. Messed with all sorts of XLR connector wiring configuration. Almost got there when I bought an isolating mixer to run the different sources through and do the switching. At some point I thought, "You know, I can just build Roy's passive crossover and then I can listen to music".

Chris said " Bob, you know as well as I that the real proponent of digital active crossovers has been and continues to be Roy. I'm merely a convert, and now a strong believer now that I've heard the difference" Chris, Roy also, if you recall, designed a Jubilee passive for Rigma. That crossover design is a masterpiece if we can take the liberty of calling something made of electronic parts a masterpiece.

Chris, You might be surprised though at how many of us with Jubilees have "been there, done that" and then gone to passive crossovers. In my case, I will give up the almost undetectable benefit of time alignment for the bliss of absolute silence when there should be silence. It is all about trade-offs in this and everything else in audio.

Pretend this post is from Dean. He asked me to post this. I don't know why, just following orders. dfhelecxover.pdf

I want company. I am so old and deaf that a set of PIO caps might sound all right to me now. Fortunately, I still got good test equipment.

I hope he prefers the correct sonic signature. I don't know exactly what warm means except as it is used to describe bathwater. I would just use correct (meaning the output of the speaker correctly presents the material on the recording) or incorrect (meaning that the speaker in some way alters what was presented to it).

I think that last post broke the forum. Dean, you gotta be more careful!

Quote above assumes a distortion component present in one cap and not in another cap. Proof please.

I have UT make most of my inductors. I buy some from Erse if they happen to be in the mood to make them. More and more of them all the time I am having UT make.

Dean said: "Did anyone read through the material in my last link? How about the one before that? LOL." No, I admit I did not. My attention span is not that long. For that particular author, I generally read the first sentence, last sentence and one sentence from about the middle. Generally that gets me by instead of reading the whole couple of thousand words.

That original 2.5mH ferrite inductor is about 0.5 ohms DCR. EDIT: Humm, we got considerably different numbers. Bob Crites

Of course there is also a matching Heresy 321.

Dean said: "Is this the same test you used to compare a Heresy II to a Heresy II with the Klipsch Upgrade Kit installed? Those were the days right after we got the CNC router and I needed a project to try out the machine. So, how about the worlds only (I think) Heresy comparitor box. The Heresy 123

Craig, Since that is what I did all those years ago, I don't see a good reason to do it again. Method was one crossover with double pole, double throw switches to instantly swap out caps for listening comparison. I was the listener, my son was operating the switch. His job was to operate that switch without me knowing (unless I could tell by listening) that he operated the switch. My job was to tell him, if I could,when he switched in the other cap. Result: With capacitance held equal, I could usually hear the difference when ESR differed by about 0.5 ohm. I have no doubt some would hear that with better resolution than me. I am, after all, old and have been around a lot of jet engines, reactor coolant pumps, steam turbines and 5000 horsepower diesel engines. My son could hear that difference at around 0.4 ohms.

Of course that would be old caps removed out of Klipsch crossovers to test the ESR theory. They are various names like Aerovox, Plastic Capacitor and others I don't remember now. What is this? A tag team.

Dean said: "Those numbers translate to less than .005 ohms for the PIO caps tested." That number is pretty good. Someone sent me some Jensen PIOs to test years ago. Was that you? None that good for sure, but the main thing is that they varied all over the place in ESR. That to me would be enough to reject using them because it speaks to the lack of control they have over their manufacturing process or materials. Same thing for rejecting any cap that advertises 10 percent tolerance on cap values. 5 percent tolerance is just not that hard to do. Bob Gassel? Haven't heard that name in a long time. Brings back old troubling memories. Dean, all you need is a heritage speaker with a 1st order network. You can then make up a double pole, double throw switch to compare caps yourself while listening. Get someone else to operate the switch and you can make those cap decisions. That is how I got to the decision that I could hear ESR when it got to about 0.5 ohms. And, capacitance being exactly equal, ESR made the only audible difference.

We can use this one as a general example of how a crossover got to be like it is. First we have the woofer and other components in the cabinet and we send a signal to just the woofer measuring the response of the woofer raw, in other words, with no crossover. We see in this case good relatively linear output to somewhere above 700hz. So, that output becomes the basis for our network. The woofer filter rolls off the woofer output at 700hz by 12db per octave. So, now we measure the raw response of the squawker. We will see it is linear from somewhere below 700hz to about 6khz. We also see that it's output is 10db higher for the same voltage signal as the woofer output. So, we use an autotransformer to decrease the output by 10db to match the output of the woofer. We also choose an appropriate capacitor (the 1.5uF) to bring in the squawker at 700hz balancing it with the woofer output frequency we limited to 700hz earlier. Now we test just the tweeter raw. We see that it is linear from around 4khz to around 18khz. Output level is about right allready to match the output of the woofer. So we just need to match it up in frequency. In this case we use a filter (2 1.5uF caps and a 160uH inductor) to bring in the tweeter at 6khz. We bring this on pretty steeply (18db per octave) since the tweeter raw would be at full output earlier than the point we want it. So now if we put in a full range signal to the complete speaker through the crossover, we should get a pretty linear output all the way up. Now this is much simplified compared to how this actually happens. It is unlikely the final design is the first try like I made this sound. At least for me, takes several tries. Also, I left out a lot of stuff about impedance and phase and where the drivers actually want to match up. So, don't get the idea that building speakers that work good is that simple. On the autotransformer question, yes, you could do that with resistors. In that case you would take a bunch of power from the amp and dissipate most of it as heat in the resistors. The autotransformer does this without ever drawing the power from the amp in the first place. Bob Crites

The number of leaking oil filled caps made in the 70s is large. It is masked on crossovers like the AA by dust in general. However, when you remove the caps, you often will see a wet spot under the cap. On a rebuild or replacement crossover, I just want that to make the speaker sound like it did when new. And I would want to verify that the same way that Klipsch did, that is, by electronic testing of the crossover. In my opinion how I want the speaker to sound or how you want the speaker to sound is just not something to consider. A rebuild or replacement crossover should make the speaker sound like the manufacturer wanted it to sound when he used those crossovers and when those original crossovers were new. Now, modification is a different story. If we want to address a change in that original performance, that is a mod. I think there are reasons that may be good to do, but then we need to call that a mod. It is not the original sound any more. Using a new high ESR cap is a mod. Must be since we know that PWK said he would not do that. Bob Crites

"So if you are tearing these caps out and the ESR is that low then why replace them at all? After all ESR is the final word isn't it?" Two reasons Craig, one is that the average one has gone high enough in ESR that it needs replacing. Second reason is that the old oil filled cans will eventually leak oil all over your speaker cabinet. I have seen hundreds of them leaking and am convinced it is just a matter of time before all of them leak.