Hi, i am wondering how the turn on/off thump is managed on other modules like UCD or ICE modules. Do they have thump might be the initial question.
If not, how the design permit a direct connection from the LC filter to the speaker?
As an example, my IR redisign uses a mute relay because upon turn on, there is a dead time forced to charge the bootstrap cap. I know UCD or ICE module differ a lot, i am just wondering because it looks like there is no relay at all.
thanks.
If not, how the design permit a direct connection from the LC filter to the speaker?
As an example, my IR redisign uses a mute relay because upon turn on, there is a dead time forced to charge the bootstrap cap. I know UCD or ICE module differ a lot, i am just wondering because it looks like there is no relay at all.
thanks.
Pierre,
Please check this http://www.diyaudio.com/forums/attachment.php?s=&postid=592333&stamp=1110300548
Jan-Peter
Please check this http://www.diyaudio.com/forums/attachment.php?s=&postid=592333&stamp=1110300548
Jan-Peter
Indeed there is only silence when you switch the UcD amp on.....
(however to be honest, when you put your ear in front of the loudspeaker you will hear a very small "thick")
We wait for one second so that the bootstrap capacitor can be fully charged, and the we switch the current source on.
We use this ON/OFF part to switch OFF the UcD when there is an overvoltage. In the first version of the UcD180/400 we used a piek current protection hereby was also this mute section used.
However we use now a constant current limiter in the UcD modules, this works in a different way and is confidential.......
Regards,
Jan-Peter
(however to be honest, when you put your ear in front of the loudspeaker you will hear a very small "thick")
We wait for one second so that the bootstrap capacitor can be fully charged, and the we switch the current source on.
We use this ON/OFF part to switch OFF the UcD when there is an overvoltage. In the first version of the UcD180/400 we used a piek current protection hereby was also this mute section used.
However we use now a constant current limiter in the UcD modules, this works in a different way and is confidential.......
Regards,
Jan-Peter
pat allen said:
Use a high value pull down from the switching node (bootstrap virtual ground) to the negative rail to ensure it has a precharge path under all conditions (no load), 47K ohm's for instance would be just fine.
Then, use a resistor + series diode from the VDD rail to the positive side of the bootstrap cap with a paralled zener across the cap of a slightly higher value than the negative supply, this way it will drop out of function during normal operation while ensuring it doesn't overcharge while not oscillating. Keep it close to the same value though, you don't want it to precharge to 15V with a 12V negative supply.
The series resistor in question will need to be sized according to the diode and zener current, how fast you expect it to charge the cap, and how big a "thick" you can stand. Also, if it is too small, it won't allow the zener to drop out under normal operation, and will keep the cap fully charged to the zener's level.
The bigger the resistor, the lesser the "thick", and the longer it will take to precharge the cap before you can enable the output stage.
You could also use a relay, flip flop perhaps retriggerable monoflop maybe, PIC, etc. to switch out the series resistor+diode precharge circuit and enable the oscillator, but it's not necessary if you do the precharge circuit right.
Non of that will help the thump from a DC offset caused by the input stage imbalance though, so that should be zero'd.
Regards
Chris
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