JKent Posted January 10, 2017 Report Share Posted January 10, 2017 22 minutes ago, Scott said: Why yes; I did find the cause; I tried to explain this in the post and attached pics I made on Dec. 5 above. Sorry--I didn't go back and read the whole thread. 24 minutes ago, Scott said: one of the speakers had a fully functional woofer and a dead tweeter; the other speaker had a fully functional tweeter and the mainly-non-functional-but-occasionally-working woofer. So both speakers always produced sound, but the sounds were never matching. Ah! Now I understand. Very frustrating. Glad you got it figured out! Link to comment Share on other sites More sharing options...
Scott Posted January 11, 2017 Author Report Share Posted January 11, 2017 OK, so unfortunately there is still a bit of a problem, even beyond the fact that I need to find another tweeter. Probably I just have to unscrew the woofer again and inspect the connections, but perhaps the cause will be obvious to one of you from the symptom: When I put everything back together, put the speakers back in their place and connected them, I was disheartened that I wasn't certain that either tweeter was in fact working. I didn't want to touch the speakers physically, in case that would knock some loose connection back into contact, but although I could hear high frequencies, I couldn't even be certain if they were coming from the tweeter or not. I learned that the crossover frequency of this speaker is 1500Hz from http://www.classicspeakerpages.net/IP.Board/index.php?/topic/2496-model-33-speakers/#comment-65141, so I used the great website www.audiocheck.net to generate some sine tones well below and above this threshold. At first, I thought it was clear that indeed now NEITHER tweeter was working. I even decided that this might be a good sign -- perhaps i had shorted something when soldering, but this gave me hope that the original 'bad' tweeter wasn't bad at all, it just needed to be more carefully wired. But then I switched around the "High Frequency Level" switch at the back -- and discovered: When the "high frequency level" switch is set to "Normal" or "Increase" -- both tweeters are completely silent. When the "high frequency level" switch is set to "Decrease" -- one of the tweeters seems to work just fine, and the other one remains silent. Of course, I can't really know if the working tweeter is giving a decreased volume of high frequency or not, since it produces no sound when the switch is in the other two positions. So my guess would be that one of the tweeters is actually bad and never produces any sound, while in the other speaker, I have badly soldered some connections, which is why the tweeter only works when the switch is in one of the three positions. Of course, it's possible that the 'bad' tweeter isn't bad at all, and it's just that the connectivity problem which appears in one speaker in two of the three switch positions is present in all the switch positions on the other speaker. I only post this in case it's 'obvious' to someone what my problem is. I will remove the woofers again tomorrow and check for shorts with a multimeter, etc. to see what i can determine. If anyone has suggestions for tests/probes I can do to verify the correct working of the "high frequency level" switch, I'm all ears.... Link to comment Share on other sites More sharing options...
Scott Posted January 12, 2017 Author Report Share Posted January 12, 2017 Is it possible that its the High Frequency (HF) Level three-way switch itself which is bad and needs to be replaced? First, is there some source of the actual crossover schematics of the Model 33? Perhaps even without them, someone can explain to me what that switch is and how it works (and what I would need to specify to get a replacement)? I am quite ignorant of these things, but it seems to me that the switch has FOUR separate connection points on top and TWO on the bottom, for a total of six. (see the picture below) Also, I am guessing that the three positions corresponding to 'increase' 'normal' and 'decrease' of the HF Level have the effect of connecting two adjacent connection points of the four point on top. Increase: connects the two left-most connection points Normal: connects the two middle connection points Decrease: connects the two right-most connection points I'm basing this on nothing more than looking at the switch. Now that I think of it, I could have of course taken a ohm-meter and at least verified that the two right most are connected when the switch is in the 'decease' position. Instead, foolhardy idiot that I am, I just made a short between the two right most points when the switch was on "decrease" and noticed that this made no difference in the sound. Armed with such 'proof', I decided I had had enough, and I shorted out the two middle connection points. Remember that when I moved the switch to "normal", the tweeter was silent. With the switch at "normal", I held a small copper wire to the two middle connection points -- and lo! the tweeter sprang into action. For the moment, that copper wire is not soldered in place to connect the middle connection points, and the speaker sounds great. It's fascinating to see how much better a two-way speaker sounds when the tweeter is actually working :). For my next trick, I will open the other speaker -- the one with the 'bad tweeter' that never works. Wont it be nice to discover that the switch on this speaker is completely broken, and that the tweeter works just fine? Since on the 'good' speaker it seems that the switch is broken in two out of three positions, I could hardly be surprised that the 'bad' speaker it is broken in three out of three. But I would be very grateful for some kind of validation/information: 1. that I have described correctly what the switch does 2. that it ever happens that these switches no longer function 3. a name or spec of the switch so that I can order a replacement Link to comment Share on other sites More sharing options...
JKent Posted January 12, 2017 Report Share Posted January 12, 2017 Scott, Just to be sure.... the photo above shows a Callins cap. This is just an old photo and you have replaced those, right? Those switches don't usually go bad AFAIK but they may benefit from a shot of De-Oxit. I don't know of any replacement. The purpose of the switch is to change the crossover point of the tweeter by routing the signal through different combinations of capacitors. -Kent Link to comment Share on other sites More sharing options...
Scott Posted January 16, 2017 Author Report Share Posted January 16, 2017 On 1/12/2017 at 2:38 PM, JKent said: Just to be sure.... the photo above shows a Callins cap. This is just an old photo and you have replaced those, right? That's entirely correct. I was embarrassed by my less-than-professional soldering skills, and was worried that displaying the newly-butchered crossover would send the wrong message to the younger and more impressionable reader here. I didn't want to be seen as condoning violence towards electronic components (or worse, of actually perpetrating it :)). On 1/12/2017 at 2:38 PM, JKent said: Those switches don't usually go bad AFAIK but they may benefit from a shot of De-Oxit. I don't know of any replacement. Would you happen either to have a schematic for the switch (or the whole crossover); or failing that; just an explanation of how it works -- that is, how each of the three switch positions connect the four connection points to each other and to the two sets of wires on the bottom of the switch. If not, I can report that I have now switched the tweeters, and it seems that the speaker that received the working tweeter is now truly and fully functional; for example, the tweeter is functional when the HFLevel switch is in all three positions. Assuming that this speaker is now "good", I can use an ohmmeter to map the swtich, and then will be able to verify if the other switch is good or not (that is, if the two switches act identically). Unfortunately for me, the 'bad' tweeter really never makes a sound; so I am now officially in the market for a tweeter. On 1/12/2017 at 2:38 PM, JKent said: The purpose of the switch is to change the crossover point of the tweeter by routing the signal through different combinations of capacitors. Would it therefore correct to state that the speaker has three crossover frequencies -- one for each of the three HF Level positions -- and that for frequencies well below the lowest crossover frequency AND well above the highest crossover frequency, the power output of the speaker is the same for all three positions of the HF Level switch. For frequencies between the two, moving the HF Level switch from 'decrease' to 'normal' to 'increase' shifts the balance between woofer and tweeter towards the tweetter -- and therefore it will get appreciably louder. To take some very concrete examples: I should expect that no matter which of the three HF Ievels I choose, a 440Hz sine wave will sound about the same. And the same is true for a 7040Hz sine tone. But i can expect that a 1760Hz tone will indeed get louder as I move the HF Level switch. I will user this to verify that the good speaker is indeed good. Lastly: I found some supposedly natural, undyed Irish linen at the local market; I've now done the grllles and they look GREAT. (Wood is still unchanged...) -scott Link to comment Share on other sites More sharing options...
Scott Posted January 31, 2017 Author Report Share Posted January 31, 2017 Just a short time after I finished everything but find a replacement tweeter --- total silence. After seemingly endless connecting and reconnecting, I think I might understand what's happened. May I just ask a question so naive it makes everything I've asked up to now seem very sophisticated: If I take an Ohmmeter and I put the two probes onto the two metal posts of a single speaker, and measure 0 Ohms (that is, the gauge says "1" when the probes are not touching anything, and it goes down to "0" when one probe touches one of the metal posts and the other probe touches the other metal post), this means that my speakers are shorted out somewhere, correct? Or is this 'normal' -- in which case, what do I do to see if my speakers have a short? The speakers are driven by an old Creek 4040S2 amplifier. I found a manual of this amplifier, which explains that there are loudspeaker fuses INSIDE the amplifier housing. It tells me that I can replace these, but these fuses generally will blow only if there is a short in the corresponding speaker circuit. I will open the amp to inspect these fuses, but if they have blown I don't want to just replace them; i need to find out if/where there is a short in the speakers. I suppose I can believe that I did a poor job and that things have shifted inside the speakers and caused a short. But I note that BOTH speakers now register 0 ohms when i put a probe on each post. It just seemed odd to me that both speakers would fail at exactly the same time. Thanks for any light you can shed on this topic for me. Scott Link to comment Share on other sites More sharing options...
JKent Posted January 31, 2017 Report Share Posted January 31, 2017 1 hour ago, Scott said: If I take an Ohmmeter and I put the two probes onto the two metal posts of a single speaker, and measure 0 Ohms (that is, the gauge says "1" when the probes are not touching anything, and it goes down to "0" when one probe touches one of the metal posts and the other probe touches the other metal post), this means that my speakers are shorted out somewhere, correct? Or is this 'normal' -- in which case, what do I do to see if my speakers have a short? Huh? By "metal posts of a single speaker" are you talking about the speaker terminals on the outside of the cabinet, or the connection points on the raw speakers? Yes. There is a short. A raw speaker should measure somewhere between 2 and 8 ohms (ish) depending on the driver and a whole speaker system in the cabinet should measure maybe 7-ish ohms. If you get zero you have a problem. If it's the terminals on the outside of the cabinet that read zero I'm going back to my previous theory that the metal machine screws that serve as terminals are shorted to the metal plate. And that would account for the silence. And it could also blow a fuse in your amp. -Kent Link to comment Share on other sites More sharing options...
Scott Posted March 16, 2017 Author Report Share Posted March 16, 2017 Just a quick follow-on post 1-2 months after completing 'phase 1' of the project: The short I asked about in my last post turned out to be something of a red-herring: somehow I left a stray bit of wire in the cabinet, which of course managed to lodge itself perfectly placed to connect one of the terminals to the metal back-plate. If I had tried to solder a connection in the same place it would not have been as robust and perfect as the one which was done by pure chance. In any case, removing it solved the problem. A month+ on, the "good" speaker really sounds nice. I even find myself using my trusty Etymotic ER-4 earphones less. The main problem is that one of the pair had a dead tweeter, and I have yet to find a KLH tweeter for sale that I can use to replace the dead one. I will try posting in the forum here, but if anyone reading this happens to have one or a pair of compatible KLH tweeters, for a reasonable price, please do let me know. It's possible that I'm just searching badly, so feel free to send me links to reasonable candidates you come across as well.These days I'm checking ebay, craiglst, and google pertty much daily. (and the buy/sell forum here, of course) Sinaly, I'm quite sure that at some ponit I read on this site some post about there being a compatible tweeter in some CSW speaker (which was also a Kloss design, of course). But I can't seem to findm y way back to that post, so I haven't been able to search for *that* tweeter. Please let me know if you can tell me what CSW model tweeter this was. Thanks! scott Link to comment Share on other sites More sharing options...
JKent Posted March 16, 2017 Report Share Posted March 16, 2017 Glad you found the problem. Nothing on eBay right now. I see a few that got away: Model 17 $14.50 Model 20 $19.99 Model (?) with logo $15.50 Model 23 $24.95 etc. etc. Keep your eyes open. I think any that look like the 33 will do but according to one AK post the 6, 17, 20, 30, 33 are probably the best match if you just buy one. Or just go with one that “looks” like yours (front and back). Don’t worry about the color of the screen. -Kent Link to comment Share on other sites More sharing options...
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