Massive hum and noise after "Stealth mod"
Hi!
Finished my first t-amp yesterday but it did not go so well. I reboxed it into a wood box. Changed the c10 cap to 2200uf 16v Panasonic but had to leave it about 1 cm above the board since the inductors left to little space. Instead of 2,2uf on the input i paralleled 2*1,5uf to get 3uf. For the volume i used a "Alps" fake Ebay pot 50k.
I do not have an ac converter so i used the batterypack and connected it with a rca plug to female chassis plug i use as connection in the box.
The noise seems like a ground problem and gets really loud espesially when i land my finger on the input caps. When my finger lands on the ic chassis plug or other components, it gets more quiet but still unacceptable loud.
I hope it is a "classic" mistake i´ve done and that it is repairable.
Happy for any help and are ready to give more info if needed.
Thanks!
Hi!
Finished my first t-amp yesterday but it did not go so well. I reboxed it into a wood box. Changed the c10 cap to 2200uf 16v Panasonic but had to leave it about 1 cm above the board since the inductors left to little space. Instead of 2,2uf on the input i paralleled 2*1,5uf to get 3uf. For the volume i used a "Alps" fake Ebay pot 50k.
I do not have an ac converter so i used the batterypack and connected it with a rca plug to female chassis plug i use as connection in the box.
The noise seems like a ground problem and gets really loud espesially when i land my finger on the input caps. When my finger lands on the ic chassis plug or other components, it gets more quiet but still unacceptable loud.
I hope it is a "classic" mistake i´ve done and that it is repairable.
Happy for any help and are ready to give more info if needed.
Thanks!
Hi a_men
Easy! Just connect the negative terminal of your battery to gound.
Or you can experiment with connecting your CD player or preamp to gound. Just run a wire from a screw on the chassis. Try different grounding points to see if you get different or better results.
Yes, Russian boxer bikes are cool! I did ride an M-72 once, loved it. I have tried to make my bike look like an M-72. FWIW, I got my sidecar start on a French boxer engine bike, the Ratier. Learned to drive a sidecar rig at the Louvre museum. No kidding.
a_men said:
Easy! Just connect the negative terminal of your battery to gound.
Or you can experiment with connecting your CD player or preamp to gound. Just run a wire from a screw on the chassis. Try different grounding points to see if you get different or better results.
Yes, Russian boxer bikes are cool! I did ride an M-72 once, loved it. I have tried to make my bike look like an M-72. FWIW, I got my sidecar start on a French boxer engine bike, the Ratier. Learned to drive a sidecar rig at the Louvre museum. No kidding.
Re. claritycaps suppliers:
The prices at diycable.com look very competitive. They're in the US, though.
The prices at diycable.com look very competitive. They're in the US, though.
power question
I'm running my Sonic Impact from a 12 V battery. I'm having trouble with noise from the portable CD player I'm using with it.
I'm using a riovolt sp90 that I'd like to power from the same battery, instead of having to change the AA's all the time.
I have a car power adaptor that works for it, it has a 4.5 V, 600mA output, but when I use it I get a LOT of noise that comes out the speakers.
The noise is from the motors in the CD player, you can hear it wind up to speed, and hear the laser track as well.
What can I do to reduce this noise?
I'm running my Sonic Impact from a 12 V battery. I'm having trouble with noise from the portable CD player I'm using with it.
I'm using a riovolt sp90 that I'd like to power from the same battery, instead of having to change the AA's all the time.
I have a car power adaptor that works for it, it has a 4.5 V, 600mA output, but when I use it I get a LOT of noise that comes out the speakers.
The noise is from the motors in the CD player, you can hear it wind up to speed, and hear the laser track as well.
What can I do to reduce this noise?
I take it you don't get this noise if you run the CD player off AA batteries?
Could be as simple as a ground loop, or it may be the power adaptor.
Do you have another 12V battery that you can use to power the CD? Even if you need to go in the car.
Also, you might try powering the CD player by battery and convertor with a different amp. The idea is that you want to figure out where the noise is getting in.
Is it coming back thru the power adaptor into the battery?
Is it a ground loop?
Is it caused by the adaptor, but coming thru the CD player?
Sorry I don't have a quick answer. But you can a least start to trace the problem.
Or maybe someone here will know the right answer!
Could be as simple as a ground loop, or it may be the power adaptor.
Do you have another 12V battery that you can use to power the CD? Even if you need to go in the car.
Also, you might try powering the CD player by battery and convertor with a different amp. The idea is that you want to figure out where the noise is getting in.
Is it coming back thru the power adaptor into the battery?
Is it a ground loop?
Is it caused by the adaptor, but coming thru the CD player?
Sorry I don't have a quick answer. But you can a least start to trace the problem.
Or maybe someone here will know the right answer!
I suspect that it's caused by the cd player, and transmitted by the power converter. It's not a hum, it's mechanical, you can hear the cd spinning.
The goal here is to power a portable cd player off of the same battery as the amp. a separate battery adds too much weight and complexity.
The power converter is very basic, being a 7805, two caps, and four diodes. I'd be willing to modify it, replace it, or get another cd player if necessary in order to quell this problem.
I'm wondering if there are recommended products that someone has had success with. or a noise filter I could add to the converter.
I'll do some testing, but I seem to remember hearing the same noise when I used this portable in my car. There I could live with it, but I've got my Sonic Impact system sounding so good, that any noise is unacceptable.
Thanks.
The goal here is to power a portable cd player off of the same battery as the amp. a separate battery adds too much weight and complexity.
The power converter is very basic, being a 7805, two caps, and four diodes. I'd be willing to modify it, replace it, or get another cd player if necessary in order to quell this problem.
I'm wondering if there are recommended products that someone has had success with. or a noise filter I could add to the converter.
I'll do some testing, but I seem to remember hearing the same noise when I used this portable in my car. There I could live with it, but I've got my Sonic Impact system sounding so good, that any noise is unacceptable.
Thanks.
Noise?
It sounds like a poor 12v to 4.5v adapter to me. Try looping the output cable from the adapter through a ferrite core. Do as many turns as you can and see what happens. This might be enough by its self or you may need to add extra filter capacitance to the 4.5 volts. This might be accomplished by opening the adapter up and adding to its existing output capacitor. More is better and low ESR is quite important.
Roger
It sounds like a poor 12v to 4.5v adapter to me. Try looping the output cable from the adapter through a ferrite core. Do as many turns as you can and see what happens. This might be enough by its self or you may need to add extra filter capacitance to the 4.5 volts. This might be accomplished by opening the adapter up and adding to its existing output capacitor. More is better and low ESR is quite important.
Roger
I tried another cd player and converter altogether, Sony units, and got similar noise.
I've already tried the ferrite choke with no reduction in noise.
Has anyone had any luck with battery sharing, or know where I should take this question?
I'm making a boombox-like system, so I'd really prefer to share the battery.
The best rechargable AA's just require too frequent changes to be practical. Nothing is more annoying than having the music die mid-CD.
I'll try a larger cap tomorrow when I get time.
I've already tried the ferrite choke with no reduction in noise.
Has anyone had any luck with battery sharing, or know where I should take this question?
I'm making a boombox-like system, so I'd really prefer to share the battery.
The best rechargable AA's just require too frequent changes to be practical. Nothing is more annoying than having the music die mid-CD.
I'll try a larger cap tomorrow when I get time.
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