So there I am with noise coming from my speakers. I did use those 1875's I had lying around. (a tube full I picked up for R20). How can you not take it? The brand, BoomTech, didn't sound promising. But at less than 50c a chip. Why not give it a go? Each channel's 2 way active crossovers with sealed enclosure compensation fed 2 BoomTech amps and finally 2 seas drivers, in sealed encloses. Just for PC speakers, but that's where you spend most of your time, so may as well get some quality.
The setup worked perfectly for a couple of years. Perhaps I was too judgemental of the BoomTech's. Not even speaker protectors in place. I know, I'm going to hell right? It all worked beautifully, so I didn't swap them out for the TI units. Then, a bit of noise, not a lot, but definitely there. Located the TI's online R100 a pop, still, only in one channel? So I fiddled the plugs, checked the supplies. Nothing helped. Only one channel. I decided to swap the amp board, I have 20 lying around so... It was still there.
This was not good, unplugged the amp from the crossover and the noise disappeared. I've sold many of those crossover boards, how could it be the cause, checked, it's not from the source. Bypassed enclosure compensation. Still there.
These were my prototype boards, that graduated to permanent use, messy, functional, they were constructed with what was on hand. Some parts migrating from an earlier revision. That's how it goes with prototypes. The noise was in the LF path. And then I twiddled the pre-set pot. Noise gone. The pot was the gain feeding the final buffer stage, the wiper must have made bad contact. But with enough leakage to keep the volume up, the poor buffer was doing the best it could with a very high impedance signal.
I'm just sharing my noisy tale in case it helps someone in the future. The recycling of the pot no doubs contributed to it's failure. Keep a suspicious eye on those electromechanical components.
The setup worked perfectly for a couple of years. Perhaps I was too judgemental of the BoomTech's. Not even speaker protectors in place. I know, I'm going to hell right? It all worked beautifully, so I didn't swap them out for the TI units. Then, a bit of noise, not a lot, but definitely there. Located the TI's online R100 a pop, still, only in one channel? So I fiddled the plugs, checked the supplies. Nothing helped. Only one channel. I decided to swap the amp board, I have 20 lying around so... It was still there.
This was not good, unplugged the amp from the crossover and the noise disappeared. I've sold many of those crossover boards, how could it be the cause, checked, it's not from the source. Bypassed enclosure compensation. Still there.
These were my prototype boards, that graduated to permanent use, messy, functional, they were constructed with what was on hand. Some parts migrating from an earlier revision. That's how it goes with prototypes. The noise was in the LF path. And then I twiddled the pre-set pot. Noise gone. The pot was the gain feeding the final buffer stage, the wiper must have made bad contact. But with enough leakage to keep the volume up, the poor buffer was doing the best it could with a very high impedance signal.
I'm just sharing my noisy tale in case it helps someone in the future. The recycling of the pot no doubs contributed to it's failure. Keep a suspicious eye on those electromechanical components.
