Can you connect a headphone to the preamp output to find out, if the hum already comes from there or if it really appears only, when preamp and power amp are connected to each other?strajo said:
Depends on the reason for the hum. If it is a ground loop and you can break it that way, yes. You would have to replace the RCA inputs with XLR inputs, which are bigger and maybe not convenient in a car.strajo said:
Hi, it is been a while...some job problems.
I solved my noise problems by adding balanced line receiver circuit to preamp input, connecting unbalanced RCA ground to receiver's cold (-IN) and signal wire to receiver's hot (+in). Schematics I used is from http://sound.westhost.com/project51.htm. Only thing I changed is removing 3k3 resistor since signal level was little lower than expected. After all, that resistor is optional, as written in text...
Right now, I'm listening my modified premp (maked new one after burning old), feeling happy...what else to say.
further plans:
1. Passive cooling
I don't like fan solution specialy in car...dust...maintaince. And it looks like that Pentium IV square heatsink isn't large enough (400cm2, even more). It becomes hot (but Il can hold it in hand) at 50 and above volume present. Of course, fan cools it down very rapidly, but passive is passive. Maybe, its wings (don't know how to say...fins?) are too close each other, so free air flow is reduced that way. And, again, after all, it is designed for fan forced air flow.
On the other hand, here is very hard to find larger heatsink, like looking for Holy Grail...some alutronics models, not very wide choice at all. And they are very expensive. So I decided to try building one from 2mm alu sheet like on http://sound.westhost.com/articles/diy-heatsink.htm
...but smaller variant, of course. I'll post results, like always. I already have 1x2m alu sheet, and need some time for cutting, drilling...
2. car testing - real environement
3. Single board layout - preamp, amp, pwr control and regulation on single one side board...compact design.
and that would be it...
best regards folks, and sorry for long posting...
I solved my noise problems by adding balanced line receiver circuit to preamp input, connecting unbalanced RCA ground to receiver's cold (-IN) and signal wire to receiver's hot (+in). Schematics I used is from http://sound.westhost.com/project51.htm. Only thing I changed is removing 3k3 resistor since signal level was little lower than expected. After all, that resistor is optional, as written in text...
Right now, I'm listening my modified premp (maked new one after burning old), feeling happy...what else to say.
further plans:
1. Passive cooling
I don't like fan solution specialy in car...dust...maintaince. And it looks like that Pentium IV square heatsink isn't large enough (400cm2, even more). It becomes hot (but Il can hold it in hand) at 50 and above volume present. Of course, fan cools it down very rapidly, but passive is passive. Maybe, its wings (don't know how to say...fins?) are too close each other, so free air flow is reduced that way. And, again, after all, it is designed for fan forced air flow.
On the other hand, here is very hard to find larger heatsink, like looking for Holy Grail...some alutronics models, not very wide choice at all. And they are very expensive. So I decided to try building one from 2mm alu sheet like on http://sound.westhost.com/articles/diy-heatsink.htm
...but smaller variant, of course. I'll post results, like always. I already have 1x2m alu sheet, and need some time for cutting, drilling...
2. car testing - real environement
3. Single board layout - preamp, amp, pwr control and regulation on single one side board...compact design.
and that would be it...
best regards folks, and sorry for long posting...
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