Hi all!!
I need help with my 6-channel preamp for 5-ch Gainclone. You can see block diagram of my preamp. Its fully working, but i have problems with some disturbances. Preamp will need some kind of mute for output, because when i switch power off, CS3310 will fail (volume to full and/or spikes,...). I have looking good muting circuit but cant find anything suitable for my preamp.
I think that preamp need also some delay when powering on. So what u think, what is best solution for this problem? Is the best way to use relays that connects outputs to ground when powering up/down??
please guys, help me
- Mika
I need help with my 6-channel preamp for 5-ch Gainclone. You can see block diagram of my preamp. Its fully working, but i have problems with some disturbances. Preamp will need some kind of mute for output, because when i switch power off, CS3310 will fail (volume to full and/or spikes,...). I have looking good muting circuit but cant find anything suitable for my preamp.
I think that preamp need also some delay when powering on. So what u think, what is best solution for this problem? Is the best way to use relays that connects outputs to ground when powering up/down??
please guys, help me
- Mika
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Hi Mika
Have you not thought of imlementing the mute function on the gainclone iself?
Yes a shorting relay will be a good idea, if the CS outputs can survive shorts. Not a wise method, IMHO.
Also reverse connected zeners will perform some limiting on the output, will prevent spikes at least. Some sonic performance degradation can happen.
As regards moving of output to full, get a soft switching circuit that switches the amp on after the preamp, and switches the amp off first. Two NE555 timers can handle it, but I'm sure you can find a better way, maybe by just using two flipflops.
That apart I am sure you will get more professional help on this soon. It would help if you checked why the spike was happening, because of removal of supply, or because of drop in the data signal, or whether the source is indeed the CS or the PIC you have used.
Have you not thought of imlementing the mute function on the gainclone iself?
Yes a shorting relay will be a good idea, if the CS outputs can survive shorts. Not a wise method, IMHO.
Also reverse connected zeners will perform some limiting on the output, will prevent spikes at least. Some sonic performance degradation can happen.
As regards moving of output to full, get a soft switching circuit that switches the amp on after the preamp, and switches the amp off first. Two NE555 timers can handle it, but I'm sure you can find a better way, maybe by just using two flipflops.
That apart I am sure you will get more professional help on this soon. It would help if you checked why the spike was happening, because of removal of supply, or because of drop in the data signal, or whether the source is indeed the CS or the PIC you have used.
Hmm...thats true that CS3310 maybe wont survive if shorting output to ground. So maybe it is better way to cut signal path like in picture? I added some resistors so signalpaths wont float.
And second problem what i forget from first post, is disturbances from mains voltage (230VAC). If i switch lights on, i can hear a spike from speakers. Will those "surge/spike suppressors" work with that problem?
- Mika
And second problem what i forget from first post, is disturbances from mains voltage (230VAC). If i switch lights on, i can hear a spike from speakers. Will those "surge/spike suppressors" work with that problem?
- Mika
Attachments
Well, yes, the series signal switching will also be good, but I was thinking not to put anything into signal path, just delayed turn-on of amp and delayed turn-off of preamp, at switch on- and off- respectively. Switching of power, not of signal. But this is kosher as well, so long as your relays are good.
As to the mains spike, you might try decoupling all the chips pins with 0.1 uF caps. May be that will help a little bit. Also check whetehr your power supply capacitance is enough, and decouple all the rectifier diodes. I don't know what your supply scheme is like, so difficult to say, but a Spike buster will *not* cure it. A properly decoupled power supply will.
As to the mains spike, you might try decoupling all the chips pins with 0.1 uF caps. May be that will help a little bit. Also check whetehr your power supply capacitance is enough, and decouple all the rectifier diodes. I don't know what your supply scheme is like, so difficult to say, but a Spike buster will *not* cure it. A properly decoupled power supply will.
I have been follwoing your 5 channel design for a little while now. Basically what I use rite now to run my theater is a Home Theater PC and I have been looking at using the gainclones in conjunction with my sound card to complete it. I am a neo-phyte when it comes to dealing with this stuff though and I am wondering if the pre-amp is needed for what I would want to do. The HTPC bascially does all the processing of my DVD and video files, I am now looking for a amp(gainclone) and speakers.
I think you should disconnect the mute pins from the PIC, wire them together and use a reset chip connected to them. The same signal could be used to reset the PIC but it isn't necessary.
One reset chip can be found here. They are SMD so they may be a little tricky to use though.
If you want software mute, write all zero into the digital pots instead.
I have used these reset chips in a number of applications professionally.
One reset chip can be found here. They are SMD so they may be a little tricky to use though.
If you want software mute, write all zero into the digital pots instead.
I have used these reset chips in a number of applications professionally.
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