I've managed to get them both playing again, by cannibalizing yet another set of 4P's.
All the elcaps were replaced by values as found in the later revision ISS.5 This means that C116 - C117 were increased in value from 10uF to 47uF. No other changes.
They both power up and play well. However, one of the two exhibits pretty loud tweeter noises (squeeking and ticking) when powering up. So badly, in fact, that one can see the tweeter moving about a mm. There must be quite some LF energy in that signal. That can't be good.
Does anybody have any idea what could be the cause of this? How come one exhibits this problem and the other doesn't?
On a side note: what exactly changes in the behaviour of the speakers when the value of those caps is increased? I understand that it has something to do with the mute-circuit. Does it kick in slower and is enabled longer..?
All the elcaps were replaced by values as found in the later revision ISS.5 This means that C116 - C117 were increased in value from 10uF to 47uF. No other changes.
They both power up and play well. However, one of the two exhibits pretty loud tweeter noises (squeeking and ticking) when powering up. So badly, in fact, that one can see the tweeter moving about a mm. There must be quite some LF energy in that signal. That can't be good.
Does anybody have any idea what could be the cause of this? How come one exhibits this problem and the other doesn't?
On a side note: what exactly changes in the behaviour of the speakers when the value of those caps is increased? I understand that it has something to do with the mute-circuit. Does it kick in slower and is enabled longer..?
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Hi @Jamesblond, did you manage to finish this project ? What was the outcome? Was the hum gone at the end ?
I have bought two pair of these today and i really like the drivers in them. Each and everyone however exhibits the same issue you talked abut. Audible hum and buzz and tweeter hiss. I would like to tackle this and wanted to know if the things you tried brought you a good solution ?
I have bought two pair of these today and i really like the drivers in them. Each and everyone however exhibits the same issue you talked abut. Audible hum and buzz and tweeter hiss. I would like to tackle this and wanted to know if the things you tried brought you a good solution ?
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