About to throw in a set of outputs in one and noticed something about the c ircuit. It is not DC coupled.
Or is it ? It has positive and negative supplies but there is no center tap on the transformer secondaries. Bottom line is there is no DC path, it all goes through the two 4,700 uF filter caps.
I have been considering the ramifications of this, and am trolling for comm ents. We know that for example in AM broadcasting the microphone polarity m atters because human speech is quite non-symmetrical. Certain musical instr uments are like that as well.
Does such a circuit reproduce such waveforms better or louder because the D C shifts and should put more on the side with the higher peaks ? (I think, I am not sure)
The print is on electrotanya if anyone would like to have a look.
I did notice though that it has no speaker protection relay, which is rare for a 300 WPC (I think) amp. But if it cannot put out any DC I guess you do n't really need a relay right ?
The floating secondaries remind me of the Crown grounded bridge, but those can put out DC. This thing apparently cannot.
Is this common in commercial amps ? I have not worked on a hell of alot of them thusfar, and actually wonder WTF else I am going to find.
That amp also has an unusual arrangement of output transistors. for each ch annel three of them are on one side of the heatsink and one is on the other side with the three from the other channel, and vice versa of course. What did they gain doing that ? It is fan cooled but I see no difference in doi ng it that way.
From what I've heard, QSC is a pretty respected brand in the music industry . Now a Crown or a Krell, but they are rugged. I also noticed this unit has common emitter outputs. Of course with this design there are reasons that is better probably.
And the thing uses a ton of one percent resistors, in places that do not se em to make sense. For example the resistors across the B-E of the outputs a re one percent, but the emitter resistors which should need to be for good current sharing aren't.
I am not befuddled here, but there are some things about this thing that do not make sense to me.
Comment, whatever, I am all ears.