If this costs you more than $40 to fix, I'll be surprised.
Sage advice there. Try swapping things around. This is stereo. Which is lucky, because we old Engineers always say "One of Anything is unmaintainable." You follow? 🙂
Like I said the problems is the voice coil is not generic vifa Aluminium dome. Since my wife is working from my living room where the speakers are, now I can’t test it until evening. theroretically I am also working !
Did you check the amp's output while playing on this speakers? We seem to agree on some thermal effect causing this. As you state you're not playing loud, it probably is some signal you do not hear. That's why I asked about possible oscillation in the amp. Measure the output, if you don't have a scope, use a (free) scope or spectrum app on your PC or something. Construct a probe (minijack connector, some signal cable, a 10x voltage divider from two resistors, some wire, shrink tube and two crocodile clamps do the magic) and measure instead of guess.
markbakk, that is a very good suggestion.
A dry joint in the feedback loop or the output Zobel. Or perhaps the Fuse is Rusty!
The suspects multiply!
Swapping out a tweeter is the easiest thing in the World. I don't know why people make such a fuss about exact replacements. They are all 1", 104mm and 91dB loudness. About 5R DCR recommended here. 😎
A dry joint in the feedback loop or the output Zobel. Or perhaps the Fuse is Rusty!
The suspects multiply!
Swapping out a tweeter is the easiest thing in the World. I don't know why people make such a fuss about exact replacements. They are all 1", 104mm and 91dB loudness. About 5R DCR recommended here. 😎
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I will report in the evening. but I cannot agree on “they are all 1”.... “ part at all. Been there done that. Yeah they all work. But the point is to have the exact same sound as the Orginal. Scanspeak vifa makes atleast 5 models of tweeters which looks exactly the same but with different resonant freq and freq response curve. So, blindly swapping a vifa 6 Ohm tweeter of the same “kind” with closer model numbers even won’t work if goal is to restore the Orginal tonality.
I tried swapping vifa ht25tg 35-06 with Ht25tg 00-06. Before on another speaker. Again same situation: one broken tweeter!
They both look the same. Both has 6 ohms. Both have sensitivity. But on testing , even though they were similarly loud, they both had different tonality when a 5 uF cap was connected in series.
Also, similarly I have the D25AG current version also at home. If you remove the faceplate they are virtually identical, but sounds vastly different.
The viscosity of the ferrofluid can be one reason as I had tried refilling one of those old tweeters with a generic ferrofluid for tweeters bought from eBay. Again between two magnets I with different types of ferrofluid, the sound was different. Lot of variables.
Dome thickness, suspension strength , fluid type, fluid amount are still variables possible even with the same coil and magnet to have different sounds.
I tried swapping vifa ht25tg 35-06 with Ht25tg 00-06. Before on another speaker. Again same situation: one broken tweeter!
They both look the same. Both has 6 ohms. Both have sensitivity. But on testing , even though they were similarly loud, they both had different tonality when a 5 uF cap was connected in series.
Also, similarly I have the D25AG current version also at home. If you remove the faceplate they are virtually identical, but sounds vastly different.
The viscosity of the ferrofluid can be one reason as I had tried refilling one of those old tweeters with a generic ferrofluid for tweeters bought from eBay. Again between two magnets I with different types of ferrofluid, the sound was different. Lot of variables.
Dome thickness, suspension strength , fluid type, fluid amount are still variables possible even with the same coil and magnet to have different sounds.
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Yeah you really need to swap the tweeters from the left and right speaker and see if the problem stays or changes to the other speaker.
I wish you well in your investigations, my friend. Even though I know little about you. Not even where you live! Or who can help you locally. You Follow? 🙂
AFAIK, tweeters are simple enough things:
Not much to go wrong there, beyond a broken voicecoil or Ferrofluid turning to sludge.
My idea of audio Royalty is Joachim Gerhard. I have heard his speakers and they are flippin' good. Interestingly he is not quite the fan of ferrofluid anymore. A cheap fix to keep the Lawyers away when things break.
But I have to agree that metal, ring-radiators, soft-domes and plastic have an entirely different sound.
AFAIK, tweeters are simple enough things:
Not much to go wrong there, beyond a broken voicecoil or Ferrofluid turning to sludge.
My idea of audio Royalty is Joachim Gerhard. I have heard his speakers and they are flippin' good. Interestingly he is not quite the fan of ferrofluid anymore. A cheap fix to keep the Lawyers away when things break.
But I have to agree that metal, ring-radiators, soft-domes and plastic have an entirely different sound.
100% agree here. As a matter of fact, you could probably take a short cut and just use clip leads with the tweeters out of the box. Are the tweeters soldered in or do they have push on terminals? While they are disconnected, it would be interesting to measure them with a DMM. Not just DCR but also inductance. I have an inexpensive DMM with LCR, frequency, temperature, etc. You could do the "touch" thing while observing DCR and inductance; I would be very surprised if the measurements were identical for both tweeters.
You could also connect a dummy resistor in place of both tweeters then measure across them with an O'scope while doing test tones, sweeps, etc. If both tweeters "test" the same; using a resistor should give you a clue as to amplifier issues, crossover, issues, etc...
I fried a tweeter once but only partially. Late night party of course; amplifier clipping causing excessive energy in the high frequencies heat up the VC wire and burn off some of the enamel, lacquer or whatever the insulating coating is. This causes a partial short circuit between some windings; I took it apart; it also warped the former.
It would still play but obviously very distorted. I'm not saying that's what's going on here in this case. And; if there is some very high frequency coming from a defective amplifier; it might do the same thing even at a lower volume setting. This is an interesting case for sure!
Another thought and helpful hint: If the tweeters are soldered in; it is safer if you just cut the wires maybe an inch or 2 back from the terminals rather than risk over heating damage to the tweeter connections. I have ruined a tweeter before because I got a terminal too hot and it became un-soldered on the inside of the housing. This was a tweeter that was NOT designed to be taken apart and repaired. You can use a butt splice with heat shrink tubing to connect it back up. You could also just splice and re-solder the wires; if you do this; I HIGHLY recommend using an aluminum clamp on heat sink designed for soldering delicate components. Put this heat sink directly on the tweeter terminal when you solder the wires; that "pulls" the heat away from the internal tweeter wiring...
As far as I know, the 3(5) stands for the air chamber behind the pole piece, the 0(0) doesn’t have this. Furthermore the ‘5’ means factory applied ferrofluid whereas the ‘0’ hasn’t. Of course that sounds different, have you compared the impedance and response curves of those two? Having said that, I can’t recall there were various alu dome butterflies when these tweeters were sold.
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I tried swapping the tweeters left and right . The treble seems not changing over time on this box. So I think when I am pressing the surrounds it’s actually changing the circuit impedance for some time which some how oscillates back to a bad “normal” in a minute or so! So wrong thread title! Now it’s more complicated as the circuit has hell lot of components which cannot be even tested with my cheapo Multimeter.
I had once contacted the manufacturer and he mentioned that this could be an inductor parallel to the tweeter but , the cap in series in only 2 weeks old mundorf. The thing is I don’t want to damage this tweeter.
I had done some repair on the crossover recently as I found the mids bit shouty. I had only replaced the parts which were Orginally there. Orginal resistors were Very well built Vishays but since I couldn’t find them anymore I replaced them with regular mox ones of the same value in ohms and watts. Also there were two things which looked like resistors - may be that could be a reason ? The Orginal caps all look perfectly fine and are philips mkt 373. To my knowledge they are reliable for very long periods. I pulled out one of them to see if they were leaking but not,and now I need a new one for its place. I have ordered couple from eBay. I doubt if they are genuine though🙁
I had once contacted the manufacturer and he mentioned that this could be an inductor parallel to the tweeter but , the cap in series in only 2 weeks old mundorf. The thing is I don’t want to damage this tweeter.
I had done some repair on the crossover recently as I found the mids bit shouty. I had only replaced the parts which were Orginally there. Orginal resistors were Very well built Vishays but since I couldn’t find them anymore I replaced them with regular mox ones of the same value in ohms and watts. Also there were two things which looked like resistors - may be that could be a reason ? The Orginal caps all look perfectly fine and are philips mkt 373. To my knowledge they are reliable for very long periods. I pulled out one of them to see if they were leaking but not,and now I need a new one for its place. I have ordered couple from eBay. I doubt if they are genuine though🙁
No those two tweeters were silk domes. I don’t have anything to measure. But they were sounding quite different when connected with a series 5 uF. I understand without measuring you cannot prove it. But it was too easy to hear. One was having more relatively more vocals and the other one has less.
Physically the texture pattern on the domes were slightly different though both domes had same curvature. I don’t have one of the tweeters now at home or else would have shown it in pictures. Upon opening up both, one had acoustic foam behind the coil and the other had a thick cloth like foam.
Another experiment was I removed the ferrofluid of one of the tweeter I had at home and replaced with another generic tweeter fluid from eBay. I have lot of tweeters at home which I bought at different points of time for several restoring projects!
Do you know anyone with electronics test equipment like a repair shop etc? If you lived by me; I could try to borrow equipment and run tests for you. What I would do is use dummy resistors in place of ALL drivers for BOTH channels. I would then insert various signals, tones, sweeps from a DIFFERENT amplifier to test ONLY your crossover boards by them selves. Troubleshooting techniques vary but one sort of rule is to only test one thing at a a time and only change one thing at a time. If you used another amplifier that rules yours out completely. I'm not at all sure what is happening when you "touch" the tweeter and how that affects the impedance the X/O "sees". Well, I live right in the middle of the USA but I wish I could help you first hand; this one really has me very curious and "buffaloed" at the same time (perplexed!)...
Thanks a lot for your helping attitude. I live in Germany and don’t have anyone around with tools to measure. If we press down the cone of a woofer, it generates some voltage at the leads, also changes the impedance seen by the crossover if I am not wrong. May be at the new impedance, the Xover point itself would shift as for a 12 dB crossover tweeters nominal impedance is one criteria for selecting the components.
Seriously wished some one near my home had similar taste in trying out things so that together 4 ears and tools would better explain than doubting if it’s placebo!
Well.
I gave you a clue in how to use your pc as a measurement device. In fact, for all your electronic measurements on speakers a pc and the 'interface' I mentioned earlier, a known resistor of about 27Ω plus a way to connect the sound output of your PC to the amp is all you will need. Even measuring impedance, inductance and capacitance in the audio band is quite simple.
The only drawback is that you have to learn how to. But I would almost promise you, you'll be enchanted when you see results popping up on your pc screen. 😉
How? Get ARTA or some app like it.
I gave you a clue in how to use your pc as a measurement device. In fact, for all your electronic measurements on speakers a pc and the 'interface' I mentioned earlier, a known resistor of about 27Ω plus a way to connect the sound output of your PC to the amp is all you will need. Even measuring impedance, inductance and capacitance in the audio band is quite simple.
The only drawback is that you have to learn how to. But I would almost promise you, you'll be enchanted when you see results popping up on your pc screen. 😉
How? Get ARTA or some app like it.
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In your fried up tweeter case mentioned here, the tweeter would always play distorted after this incident right ? In my case on cold start it’s perfectly alright for a minute or so. Then distortion I mean more vocals starts to slowly appear in the tweeter. Did you had this behavior ?
I have thought about this as well. Is there anything that shows a schematic, block diagram for users, instructions, ARTA tips and hints, etc???
Thanks!
I would say so since it didn't move with the tweeter when you tried it in the other box.
It might be worth resoldering the solder joints on the crossover board at this point to see if that fixes it.