Hello. I built this serial fx loop as drawing below. It work very well with two small issues: First it raise a bit of noise - very extremely slight but still here when 5ft. patch cables connects.(I can pass that). Second it slightly pops when I engage any pedals I have ( not any external noise, just popping when engage the foot switch). All my pedals are supplied from mains from 9V independent smps adapter supplies. Please help how I can cure the popping noise when pedals engage please ? Thanks.
The level of noise is dependent by 100k pot position. More loud as the pot is more open. Should I isolate the recovery stage input with a cap please ?
Late: oh no, a cap at input recovery stage did not do a difference...more, it seems it pops a bit louder than before...A capacitor from the whiper output to pedal input did not helps either...
There are not ground loops, supplies are galvanic isolated by separation transformer...just a comute regime I cannot get rid of...
The level of noise is dependent by 100k pot position. More loud as the pot is more open. Should I isolate the recovery stage input with a cap please ?
Late: oh no, a cap at input recovery stage did not do a difference...more, it seems it pops a bit louder than before...A capacitor from the whiper output to pedal input did not helps either...
There are not ground loops, supplies are galvanic isolated by separation transformer...just a comute regime I cannot get rid of...
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If I take the cable from CF output out and left just recovery stage input connected at output of pedal (cf output disconected) I still hear a very discrete pops when engage the foot switch but Is a huge difference. How could I tame the loud pop when cf is connected to the same discrete pop level when just the pedals output is connected, please? Thanks
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http://www.geofex.com/Article_Folders/box_pop.htm
https://www.harmonycentral.com/foru...oud-quotpoppingquot-sound-when-turning-onoff/
It may help.
Though, I can see a 1M resistor at the input , and the output from the cap it feeds into the transformer I assume ? if not that cap has no resistor to ground.
https://www.harmonycentral.com/foru...oud-quotpoppingquot-sound-when-turning-onoff/
It may help.
Though, I can see a 1M resistor at the input , and the output from the cap it feeds into the transformer I assume ? if not that cap has no resistor to ground.
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Thanks for reply.
The CF output (send) is loaded by 100k resistance of the potentiometer in paralel with input impedance of the first pedal. This is the place where those nasty popping transient comes. (If I grounded the input of first pedal in chain- meant CF output potentiometer completely closed- the popping noise is almost non present)
The output of the last pedal in chain is loaded by 1M input impedance of recovery stage.
The CF output (send) is loaded by 100k resistance of the potentiometer in paralel with input impedance of the first pedal. This is the place where those nasty popping transient comes. (If I grounded the input of first pedal in chain- meant CF output potentiometer completely closed- the popping noise is almost non present)
The output of the last pedal in chain is loaded by 1M input impedance of recovery stage.
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I installed a 10k resistor in parallel with the 100k pot to provide an alternative path for charging current. The popping noise is substantially reduced...!!!
I wonder if I broke the actual grounding path to force the charging current to return directly to it's own decoupling cap will help more...???
I wonder if I broke the actual grounding path to force the charging current to return directly to it's own decoupling cap will help more...???
...and that's my latest solution...The popping is extremely hard perceptible. Please let me know if you see some cons against circuit, if any ? Thanks.
Frequency response from 10cps to 1kcps.
Frequency response from 10cps to 1kcps.
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If it works , thats good. You can also try a smaller value pot, 10 - 20k without the 10k res, or maybe the res after the pot, from wiper to gnd.
Im not sure it's a good practice to break the gnd like that, does it affect the sound ? .
The ground connection might still be somewhere else in the circuit ? I don't see how it will work like that. And if there is another ground connection, there might be a ground loop problem that is fixed by lifting the ground like you did. I might be wrong tho
Im not sure it's a good practice to break the gnd like that, does it affect the sound ? .
The ground connection might still be somewhere else in the circuit ? I don't see how it will work like that. And if there is another ground connection, there might be a ground loop problem that is fixed by lifting the ground like you did. I might be wrong tho
What you hear in my last vid is the noise comming directly from a 98db speaker at 20cm distance from the cone with all controls dimmed. There is no any loop to generate any noise in the circuit...You may still hear the noise from commuting if listen extremely carefully, but hey this true bypass switches comute the pedals input AND output in the same time, but the noise problems comes from the front.
And a test switching with 10k load only as you suggest (don't have a 10k pot at hand but replaced with a fixed 10k resistor). The 1uF cap and 100k pot was removed.
Is not as loud poping as 100k load but way far in in term of popping noise with the circuit tested before...which was close to absolute none.
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The signal ground should be broked somewhere by choice relative to my drawing in the first post. I think is no good to run signal return from bus ground and in the same time to tie the send and retur grounds both to the bus as it will make the second parallel signal ground return path through the send/return patch cables. One grounding point for pedals ground should be enough and will be just at one end, meant or send or return jack. I did the pedal ground connection at return jack. But I did so many grounding variations, including both ends grounded....in my amp it seems not do any diference in terms of noise. But the only way to tame those popping transient, was to stack 10uF / 10k - 1uF / 100k, no matter how I choose to run the ground return
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Found the same "stacking" arangement used in peavey 5150. C53/R103 followed by C65/R33. Any thoughts ?
Relative to grounding I see only two options available for a certain grounding scheme: ( bus grounding in my case). The ground return may be tied directly at the grounding point where the fx adress, meant point B, or at the very first point to chass, meant point A. I tried both and found point A is more quiet generaly speaking...BUT cables seems to be more sensitive in this point. I build two unique sense cables ( meant stereo cables with signal and ground running inside/ shield tied to one end) to see if help to get rid of external noise. The pedals are supplied by batteries now to exclude any possible loop.. That is basicaly schematic I used figured only the fx stage I have connected at the moment.
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This
Still a tiny bit fraction of noise, think is inevitable. Is almost dead, but is there.But is from screen cables interference. From certain positions of the cables is absolutely dead. The only noise it may colect is from cables shield, so is external, in respect with the position of the cables in the house. The way the connections I done do not generate any conflict.
Still a tiny bit fraction of noise, think is inevitable. Is almost dead, but is there.But is from screen cables interference. From certain positions of the cables is absolutely dead. The only noise it may colect is from cables shield, so is external, in respect with the position of the cables in the house. The way the connections I done do not generate any conflict.
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Now, maybe it is time to use a sereo send jack and connect the signal ground to the ring and the cable shield to the first end of the bus, where the bus is connected to chassis...to see if do a difference..
One observation regard the send cable:
The shield tied only to the chass make the cable more imune to the noise in respect with its position but carry a tinny fraction of noise which is pretty consistent.
With the shied tied only to signal gnd (bus) the noise induced vary with cable position, but for certain positions is absolutely dead.
So I think I.ll come back to the scheme from post 16.
The shield tied only to the chass make the cable more imune to the noise in respect with its position but carry a tinny fraction of noise which is pretty consistent.
With the shied tied only to signal gnd (bus) the noise induced vary with cable position, but for certain positions is absolutely dead.
So I think I.ll come back to the scheme from post 16.