Recently I've completed building Jim Holtz's Finalist Speaker, it is an amazing speaker that can easily be compared with Paradigm Prestige 95F that I own still. My speaker was made along with subwoofer placed in the same box, upper portion of the speaker is ported Finalist and the bottom part is a sealed 8" sub. The amp is DIY made with a class D 200 watt amp from ebay and a low pass filter from ebay. It is powered by 50 toroidal transformer with a DIY power supply filter. The speaker is driven by a rotel rb 1582 power and rc 1550 pre.
Now the problem is,
1. when I connect the speaker without any input in the amp, the sub makes hum. Lets say, if I switch off CD player keeping the amp turned on it makes the noise, or even, when I change the source from pre, if that does not have any source connected like TV or cassette if makes noise. If the source is connected and turned on with amp there is no noise. I checked up with my main system that is a Brysyon sst4 b, it has the same problem. Is it for not having a speaker level to line level converter with sub input or something else.
2. When I turn off the sub power it makes a noise like something is discharging. It may be for the power supply filter. I have gone all with DIY because I enjoyed it, but I have no knowledge in electronics. Can someone please help with a solution.
Now the problem is,
1. when I connect the speaker without any input in the amp, the sub makes hum. Lets say, if I switch off CD player keeping the amp turned on it makes the noise, or even, when I change the source from pre, if that does not have any source connected like TV or cassette if makes noise. If the source is connected and turned on with amp there is no noise. I checked up with my main system that is a Brysyon sst4 b, it has the same problem. Is it for not having a speaker level to line level converter with sub input or something else.
2. When I turn off the sub power it makes a noise like something is discharging. It may be for the power supply filter. I have gone all with DIY because I enjoyed it, but I have no knowledge in electronics. Can someone please help with a solution.
Do you mean the noise comes and goes as you power sources up and down, not as you connect or disconnect them?
yes, amp output is connected to low pass filter. What should be the approach or the alternative, please put some light.
yes, amp output is connected to low pass filter. What should be the approach or the alternative, please put some light
Thanks, the low pass filter has volume control, I found following information from this forum
"3 resistors in series. The two outer ones 5.1k each and the middle one 1k. The headunit speaker connections go to the two outer ends, the amp connects to the 1k inner resistor.
This gives approx 10 times attenuation. You must connect left and right exactly the same or you will get out of phase channels."
I also heard that attenuating input in this manner may cause problem to some maun amp. need your kind suggestions.
Using three resistors sounds a bit odd. This should be all you need, you might have to experiment with the resistor values, the output is simply divided buy an amount equivalent to the resistances. Otherwise known as a "potential divider" -- http://www.epanorama.net/circuits/speaker_to_line.gif
Can't say as I understand your description, but you might try an audio isolation transformer somewhere in the chain, esp towards the end. I bought a bunch with RCA input and output cables on eBay for like $12. They measure as close to perfect as I want and, sure enough, they do their magic.
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