Hi folks,
we are now have different statements for what could be wrong in one of these amps.
Now at this point I would check the phase shifting of this amp at different frequencies with a signal generator and and a dual trace scope.
Both amps driven from the from the generator by paralleling the inputs of the amps. Each amp is connected to a dummy load and the outputs monitored with the scope.
If the amps working properly, so both traces on the scope will absolutely the same at all frequencies in the audio spectrum.
This will show the truth what´s wrong with one of these amps.
73
Wolfgang
we are now have different statements for what could be wrong in one of these amps.
Now at this point I would check the phase shifting of this amp at different frequencies with a signal generator and and a dual trace scope.
Both amps driven from the from the generator by paralleling the inputs of the amps. Each amp is connected to a dummy load and the outputs monitored with the scope.
If the amps working properly, so both traces on the scope will absolutely the same at all frequencies in the audio spectrum.
This will show the truth what´s wrong with one of these amps.
73
Wolfgang
check the easy things first
Just like was suggested by many of you, I reversed one of the speaker leads and, what do you know the problem is solved(almost). I am sorry I was reluctant to try this from the beginning. The story goes on from here and I'm embarrassed to say I am to blame. A while back I rewired the speakers because the original wires was corroding on the ends(turned green several inches up the wire from the ends) that was soldered by the factory. The tweeters had +- marked terminal, the mid/bass were not marked. The mid/bass unit looked to be made the same so I marked ONE but not the other. It turns out that when dynaudio made the mid/bass units, physically they were 180 degrees different. That is the basket on the back was turned so that the coil terminals were also 180 degrees shifted physically. I found this by connecting(momentarily) a D size battery to the terminals and observing the in or out motion of the unit. Well, that's what I get for assuming that the speaker units were Identical, and not following completely through on the marking of polarity.
I had the speakers connected crosswise originally which put the mid/bass units in phase. So after all said, I have had a the tweeters out of phase(so much for my hearing abilities). I arrived at this recent problem as I had connected a dummy load to the amp after the blow out to check out the amp with the bad EL34. Then reconnected them following the cable coding and thus put the mid/bass out of phase and the tweeters in phase. Just want to crawl under a rock. It turns out that it sounded quite good with the tweeter out of phase.
Just like was suggested by many of you, I reversed one of the speaker leads and, what do you know the problem is solved(almost). I am sorry I was reluctant to try this from the beginning. The story goes on from here and I'm embarrassed to say I am to blame. A while back I rewired the speakers because the original wires was corroding on the ends(turned green several inches up the wire from the ends) that was soldered by the factory. The tweeters had +- marked terminal, the mid/bass were not marked. The mid/bass unit looked to be made the same so I marked ONE but not the other. It turns out that when dynaudio made the mid/bass units, physically they were 180 degrees different. That is the basket on the back was turned so that the coil terminals were also 180 degrees shifted physically. I found this by connecting(momentarily) a D size battery to the terminals and observing the in or out motion of the unit. Well, that's what I get for assuming that the speaker units were Identical, and not following completely through on the marking of polarity.
I had the speakers connected crosswise originally which put the mid/bass units in phase. So after all said, I have had a the tweeters out of phase(so much for my hearing abilities). I arrived at this recent problem as I had connected a dummy load to the amp after the blow out to check out the amp with the bad EL34. Then reconnected them following the cable coding and thus put the mid/bass out of phase and the tweeters in phase. Just want to crawl under a rock. It turns out that it sounded quite good with the tweeter out of phase.
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