Anyone know the best way to stop popping noises when turning up volume?
I recently installed this in my linestage:
Balance XLR 23 Stepped Attenuator Potentiometer 50K Log | eBay
However the "thud" each time I turn up the volume is rather annoying - there is no dc offset at the source. Can I install some kind of capacitor to stop the noise?
I recently installed this in my linestage:
Balance XLR 23 Stepped Attenuator Potentiometer 50K Log | eBay
However the "thud" each time I turn up the volume is rather annoying - there is no dc offset at the source. Can I install some kind of capacitor to stop the noise?
The noise is because of the voltage across the input capacitor. Try installing an 100-150K resistor from the potentiometer output to the ground, so the capacitor does not have a terminal "in air" during switch-over.
Personally I hate any potentiometer over 10kohms - too much noise pick-up.
Personally I hate any potentiometer over 10kohms - too much noise pick-up.
There may be some dc present, but the real caused of the popping is probably that it is not a make before break switch. I believe that the pop occurs because when the contact breaks the dc has a chance to build up momentarily (even if you have caps,) a make before break switch ensures there is no break in continuity when switching from one resistor to the next.. Since they say "no noise or bopping when switching" you might want to take them to task over it.
Tony.
Tony.
Thanks for the assistance, I’ve tried a few difference sources and the problem remains – might email the seller and try the complaint path!
In order to try the resistor suggestion – I’m using a pcb which has both balanced and unbalanced in.
See here:
http://www.diyaudio.com/forums/tube...reamp-w-balanced-input-strange-schematic.html
Where is the best position to install the resistors – on the board between +,- and gnd for the balanced section?
In order to try the resistor suggestion – I’m using a pcb which has both balanced and unbalanced in.
See here:
http://www.diyaudio.com/forums/tube...reamp-w-balanced-input-strange-schematic.html
Where is the best position to install the resistors – on the board between +,- and gnd for the balanced section?
update - the seller has replied:
"Dear Sir:
This potentiometer is 'contact before break' type, so it should not generate pop sound.
What you hear my induced by impedance change during potentiometer shifting. This type of potentiometer, amplifier will not see constant input impedance. Some circuit will generate noise from impedance shifting. It seems no simple method to solve this problem.
Sincerely"
any ideas?
"Dear Sir:
This potentiometer is 'contact before break' type, so it should not generate pop sound.
What you hear my induced by impedance change during potentiometer shifting. This type of potentiometer, amplifier will not see constant input impedance. Some circuit will generate noise from impedance shifting. It seems no simple method to solve this problem.
Sincerely"
any ideas?
If its a "crack" instead of a "thud" you could try cleaining it with an electronic solvent like "CO contact cleaner".
I had a DACT stepped attenuator that was noisy, cleaned it one and it has not faulted in 5 years.
I had a DACT stepped attenuator that was noisy, cleaned it one and it has not faulted in 5 years.
To get minimum clicks you need no DC coming in and no DC going out. That means coupling caps both ends, with a ground leak on the switchd side (probably output). Your preamp appears to connect straight to a valve grid. That may be the problem - you are switching a little grid current. With a continuously variable pot you can sometimes get away with dropping a coupling cap (although you get noise long term) but you can't do this with a switch.
thanks again guys - the source runs straight to the pot, which connects to the preamp. Appears I may need to install a "ground leak"? Is this the 100k to 150k resistors that sonic_real_one mentions above? If so, what is the simplest way of doing this?
You need caps plus a ground leak, unless your source already has caps. I'm not sure what you mean by "simplest".
my source doesn't have caps, - it's just an ad1865 dac chip with 220R i/v resistors. there is a few mV of dc offset (but I tried other sources which do have caps and the popping noise on the attenuator is there nevertheless)
I'll try the resistors, test, then try some caps at the output of the DAC. How do we work out the values of; (a) the resistors (someone suggested 100-150k), and (b) the caps at the output.
I'll try the resistors, test, then try some caps at the output of the DAC. How do we work out the values of; (a) the resistors (someone suggested 100-150k), and (b) the caps at the output.
With no DC isolation at input or output it is not surprising that you have clicks. You need caps at both sides. Resistors on their own will do nothing, as the purpose of the resistors is to maintain the DC voltage on the coupling caps in mid-switch. So for each channel you need an input cap, an output cap, and a high value resistor from the attenuator output to ground (1M would be fine).lordearl said:
The cap values depend on the resistive load, and what LF point you want. There are calculators on the web, or some of us on here can do arithmetic if you ask.
Ok in order to commence the process I have soldered the resistors tonight. I soldered 100k to ground for both channels and the pop/thud has definitely improved. It is still there but is noticeably softer.
I've tried two sources (cd player - caps at the output, DAC - no caps as per previous post) and also just the preamp straight to the power amp (no source) and the pops/clicks are present in each case.
DF96 - where do you suggest I put the caps you mention? Should I increase the 100k resistors to 1M?
I've tried two sources (cd player - caps at the output, DAC - no caps as per previous post) and also just the preamp straight to the power amp (no source) and the pops/clicks are present in each case.
DF96 - where do you suggest I put the caps you mention? Should I increase the 100k resistors to 1M?
Are you asking where to put the caps electrically, or mechanically? I'm not sure what your level of understanding is. They are just coupling caps. The resistor value is not critical: it needs to be significantly higher than the attenuator resistance, and significantly lower than the caps leakage resistance. Anything from 100k to 1G?
At present you have two sources of clicks: DC offset from the source, and grid current in the line stage. Avoiding/fixing just one of them will still leave you with clicks.
At present you have two sources of clicks: DC offset from the source, and grid current in the line stage. Avoiding/fixing just one of them will still leave you with clicks.
I'll try a higher resistor value.
The clicking is there no matter what source (or no source) I use, whether coupled or not...
The clicking is there no matter what source (or no source) I use, whether coupled or not...
You need to be AC coupled on both ends (series caps) and have resistors to ground on the switch side of both caps to ground. At least start there, as that's about as good as it's going to get.
My suggestion is stop buying cheap Chinese crap. I bought the same crap from Hong kong and it lasted two month, It first started with a Pop in one of the Low level settings and than it went everywhere on and off. Finally, I got a Goldpoint and not one single problem since and that was 5 months ago.
Ps. And I too left Postive Feedback.
Ps. And I too left Postive Feedback.
Last edited:
haha yes well that could be the cause! Although $50 is arguably not *that* cheap...
Perhaps it is smarter to install the caps within the preamp unit itself rather than in the the source dac...then the problem won't persist if I change sources.
There are two inputs -xlr and rca, I assume I solder the capacitors from the signal wires to ground, just as if it were a low pass filter at the output of a dac?
Perhaps it is smarter to install the caps within the preamp unit itself rather than in the the source dac...then the problem won't persist if I change sources.
There are two inputs -xlr and rca, I assume I solder the capacitors from the signal wires to ground, just as if it were a low pass filter at the output of a dac?
Install a DC blocking capacitor in the output of every channel of your source/s. Ground the output of that DC blocking cap with a high value resistor.
This can get very expensive if you need High Fidelity and have low Zin receiver equipment.
A cheaper alternative is to DC block the final source before the attenuator. This way you only need two good quality capacitors and you can ensure they have the correct value to suit the Zin of the attenuator.
Now to the Receiver:
Any designer/manufacturer that supplies a DC coupled link direct to the valve grid should be strung up !!!!!!
Install a DC blocking capacitor at the input to your amplifier. Determine the value of this capacitor to allow the passband you require to pass through. Ground the input side of that DC block with a high value resistor.
Check the output offset and output noise before and after modifying the input.
This can get very expensive if you need High Fidelity and have low Zin receiver equipment.
A cheaper alternative is to DC block the final source before the attenuator. This way you only need two good quality capacitors and you can ensure they have the correct value to suit the Zin of the attenuator.
Now to the Receiver:
Any designer/manufacturer that supplies a DC coupled link direct to the valve grid should be strung up !!!!!!
Install a DC blocking capacitor at the input to your amplifier. Determine the value of this capacitor to allow the passband you require to pass through. Ground the input side of that DC block with a high value resistor.
Check the output offset and output noise before and after modifying the input.
No, each source needs a separate cap otherwise you get clicks when changing inputs.lordearl said:
No, these are coupling capacitors. They go in series with the signal wires, not to ground.
- Status
- Not open for further replies.