since there are no warnings about this on RC filter guides i guess the statement above is true
it also makes more sense since the resistor itself would need a direct ground connection to actually "burn" wattage which is the case in a voltage devider for example
So i guess i will buy some 10 ohm 5W resistor to test this with my current boards
maybe there is also a audible difference because the DC filter frequency gets shifted even further down with a resistori just need to cut the trace from switch to supercap and solder a resistor from supercap + pin to the right switch pin
i just bought these: https://de.aliexpress.com/item/1005005621955006.html 10 ohm 5W metal film ones, metal film seems to be a good choice from what i read and im not too concerned about quality with resistors (since i bought on aliexpress) ...
Also the CDA supercaps arrived yesterday, unfortunaly with some bent pins but still useable
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since noone yet wanted to (seriously) buy one, i might end up sending some prototypes for free (against shipping cost) before i start a next revision, but i have to see, i would still like to recoup some of the money i spent in research and testing, tho i also wanna get some other opinions we might get the ball rolling once other people heared it and can report back
My offer for 20euro per board (including shipping inside germany, international you have to pay shipping) still stands for a bit
if tests dont go wrong you get a fully working prototype with the resistor, so no risk in frying usb ports... i probably can finish them in around 7-10 days when the resistors arrive
the other issue with ground resistance has to be avoided manually, just set the ground passtrough switch to on as long you use PC power since i cant gurantee that the dac is grounded elsewhere in each setup...
if you use a external power supply (or know what you are doing) you can play around as you wish
EDIT: if someone doesnt like this after testing, if you pay shipping cost you can sent it back "for free" and get your 20 euro back if unsatisfied (for 30 days after arrivement)
Also the CDA supercaps arrived yesterday, unfortunaly with some bent pins but still useable
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since noone yet wanted to (seriously) buy one, i might end up sending some prototypes for free (against shipping cost) before i start a next revision, but i have to see, i would still like to recoup some of the money i spent in research and testing, tho i also wanna get some other opinions
we might get the ball rolling once other people heared it and can report back My offer for 20euro per board (including shipping inside germany, international you have to pay shipping) still stands for a bit
if tests dont go wrong you get a fully working prototype with the resistor, so no risk in frying usb ports... i probably can finish them in around 7-10 days when the resistors arrive
the other issue with ground resistance has to be avoided manually, just set the ground passtrough switch to on as long you use PC power since i cant gurantee that the dac is grounded elsewhere in each setup...
if you use a external power supply (or know what you are doing) you can play around as you wish
EDIT: if someone doesnt like this after testing, if you pay shipping cost you can sent it back "for free" and get your 20 euro back if unsatisfied (for 30 days after arrivement)
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Ah one thing more, unrelated but might be important for some buying decisions...
I actually bought the new interface (black lion audio 2x2 revolution) so im able to record in high-ish quality, i will probably get soon some microphones and start testing wether i can spot differences in the recording which i also hear in RL on my setup, if things work out i might be able to do a small comparison video of this plug compared to ifi isilencer etc...
also im probably able to offer flac files so youtube is no excuse
I actually bought the new interface (black lion audio 2x2 revolution) so im able to record in high-ish quality, i will probably get soon some microphones and start testing wether i can spot differences in the recording which i also hear in RL on my setup, if things work out i might be able to do a small comparison video of this plug compared to ifi isilencer etc...
also im probably able to offer flac files so youtube is no excuse
Hi Ghostknight,
sorry for my late reply, i had some personal issues...
Yes i am still interessted if you still have one unit available
I will send you a PN
oh no problem, i thought you are not interested anymore
i will tune the prototypes a bit more before i will sent them out, i also got another member that wants to try this and compare it to a similar setup than mine, he currently uses Topping HS02 + 2x Ifi Isilencer, it will be also interesting what he will think
Since im adding the resistor there is also no real harm in adding a bigger supercap, i still have some 15F ones, which i will try once the resistors arrive and maybe include in the prototypes, since i plan to use more capacitance in the next version anyway
Hi there! Might be a little bit out of topic but I need help!!
I’m trying to make a music live setup consisting of two wireless audio transmitters powered by a usb power bank through a battery eliminator and an effects pedal which is powered by the same power bank but I get some noise. It’s a loop ground noise and I added in the usb line to the effects pedal a ground loop isolator consisting of two transistors and the noise went of by about 80%! When i turn the volume to max I can still hear this loop noise from the ground signal! Is there anyway to totally eliminate it? Thinking of adding a second ground loop isolator between the transmitters and the power bank. Would this work? Is there if you know a power bank with build in isolators? Is it relevant to your project? Thank you very much!!
I’m trying to make a music live setup consisting of two wireless audio transmitters powered by a usb power bank through a battery eliminator and an effects pedal which is powered by the same power bank but I get some noise. It’s a loop ground noise and I added in the usb line to the effects pedal a ground loop isolator consisting of two transistors and the noise went of by about 80%! When i turn the volume to max I can still hear this loop noise from the ground signal! Is there anyway to totally eliminate it? Thinking of adding a second ground loop isolator between the transmitters and the power bank. Would this work? Is there if you know a power bank with build in isolators? Is it relevant to your project? Thank you very much!!
is this possible with transistors?
Hmm which kind of power bank are we talking about? i never seen one tho
i also dont know what a "battery eliminator" is
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your text is quite hard to understand, to really help you and see whats going on, could you make a picture showing all connections and devices?
my guess is if you use usb of some kind you could also use my filter, but in theory your setup with wireless audio transmitter should (or could) be ground loop free, in theory atleast, specially with power banks
Oh, i got it i think, Battery Eliminator Circuit to get rid of the second power bank, right?
IMO if you have a ground loop in the system actually using 2 seperate power banks could fix your problem, but please make a picture so i see if i got things right
Soo, kinda bad news
resistors arrived and i think i got something wrong theory-wise ... even with 5 ohms resistance, after plugging the dac in voltage dropped to 2,83V
Tho, im not quite sure how i calculate the voltage drop, seems like RC filter just can be used on static loads where the load resistance is known?
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Question now is what we can do else for a next revision... IMO a power switch IC is the simplest solution here i think and actually would offer different settable current limits, so the usb filter could be used as a nice 2A power filter only too, larger capacitances should be no problem with this solution either
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The only thing i can report on right now... i tested after the failed resistor test how the different supercaps performed i had... they were HiCon 5F 5.5V, not 15F like i said before.... the burn in was pretty real on the 5F one and im quite unsure if its "better" yet, it sounds different tho, i will leave it connected for 2-3 days and compare again, currently i would say the Eaton 1,5F one sounded smoother/more coherent while the 5F brings out more transients
Also i should compare the CDA 1,5F i got to the eaton, just to see whether values matter here or actually the manfacturer/construction of the cap
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About the Prototypes... i think i will have to send them out like they are now, with the risk of overloading the power supply, tho like i said before, i have no problem whatsoever using a Ifi power X 5V 3A power supply, the charge process only takes a few seconds, but i havent tested yet what happens if you charge the unprotected cap with a low power power supply like from your usb (500mA), i think some will shut down because the cap charging looks like a short
if people feel safer i could remove (or glue) the voltage selector switch, so PC power cant be used at all and you have to use a external power supply
resistors arrived and i think i got something wrong theory-wise ... even with 5 ohms resistance, after plugging the dac in voltage dropped to 2,83V
Tho, im not quite sure how i calculate the voltage drop, seems like RC filter just can be used on static loads where the load resistance is known?
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Question now is what we can do else for a next revision... IMO a power switch IC is the simplest solution here i think and actually would offer different settable current limits, so the usb filter could be used as a nice 2A power filter only too, larger capacitances should be no problem with this solution either
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The only thing i can report on right now... i tested after the failed resistor test how the different supercaps performed i had... they were HiCon 5F 5.5V, not 15F like i said before.... the burn in was pretty real on the 5F one and im quite unsure if its "better" yet, it sounds different tho, i will leave it connected for 2-3 days and compare again, currently i would say the Eaton 1,5F one sounded smoother/more coherent while the 5F brings out more transients
Also i should compare the CDA 1,5F i got to the eaton, just to see whether values matter here or actually the manfacturer/construction of the cap
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About the Prototypes... i think i will have to send them out like they are now, with the risk of overloading the power supply, tho like i said before, i have no problem whatsoever using a Ifi power X 5V 3A power supply, the charge process only takes a few seconds, but i havent tested yet what happens if you charge the unprotected cap with a low power power supply like from your usb (500mA), i think some will shut down because the cap charging looks like a short
if people feel safer i could remove (or glue) the voltage selector switch, so PC power cant be used at all and you have to use a external power supply
So after 1-2 days and switching back and forth again i would say the HiCon 5F cap "smoothed out" and actually offering better transient response, cleaner highs and more powerful bass, i will include the 5F cap for the prototypes, let me know what you will hear, specially the first few hours vs burned in 50-200 hours
i can glue the power selector in place, so it just accepts external power supplys for power, this essentially also fixes the grounding issue i talked about before, when using pc power but using resistance over ground
im still questioning whether i should add a switching mechanism on the next pcb or only make external power supplys work... imo you always want to use a external power supply.. well unless you dont have one
i wanna try something... because i had some thought the last couple of days
i wanna build a small dongle with 1 common mode choke IC and a switch to let pc power trough, this one can be plugged into the pc and is basicly a "sister board" to the main filter that should sit shortly before the dac (i will probably also try some DIY 10cm cables here)
tho im still unsure why 2 filters after eachother didnt work, common mode chokes degrade the signal quality to some degree, my guess is 4 common mode chokes are just too much, so i will try this sisterboard with 1 common mode choke to see whether 3 work... if not i will reduce the common mode chokes to 1 on the main filter
a schematic will follow soon
i wanna build a small dongle with 1 common mode choke IC and a switch to let pc power trough, this one can be plugged into the pc and is basicly a "sister board" to the main filter that should sit shortly before the dac (i will probably also try some DIY 10cm cables here)
tho im still unsure why 2 filters after eachother didnt work, common mode chokes degrade the signal quality to some degree, my guess is 4 common mode chokes are just too much, so i will try this sisterboard with 1 common mode choke to see whether 3 work... if not i will reduce the common mode chokes to 1 on the main filter
a schematic will follow soon
You seem to focus a lot on big F capacitors.. I didn't look at your schema in detail bt it seems it may be the wrong focus. It's not a power source. It's a data line conveyor. And I cant see why/how such a function could make any reasonable use of 1F capacitance. You share power and (some) ground between in and out. A real galvanic isolator with possibility to feed external power to the downlink side will be much more efficient in what your goal with this is. Using fancy components won't help if the basic idea don't fly....
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well i talked before about the RC filter properties of the supercap, no measurements tho but it does make a audible difference, wether the audible difference from bigger caps come from the RC filter properties or low ESR i cant say yet but i pretty much always noticed improvements with supercaps
common mode chokes on the data lines should be also pretty clear... after some more testing i also recommend ferrite beads (preferably at each cable end 1), as long the music/dac doesnt break up or loses connection you cant really go wrong with ferrite beads imo (the large change is imo only EMI filtering... and some people seem to prefer it) just be careful with ferrite beads on analog (audio) signal cables
we had power, data lines, and now ground is "isolated" trough a resistor with a clean external power supply, 333 ohms work very reliably in my tests .... i probably will add 333/200/100 ohm (or something like that) in the next revision
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this is the sister board i talked about:
basicly just the first stage of my filtering concept
i added a switch to disable V+ because there is no need to carry "dirty" power along the cable if we use a external power supply anyway at the other end
i did not add ground resistance because the "termination resistor" should sit at the other end, close to the dac, so all EMI has trough the GND line in the cable still a low resistance path to (another) ground
i will see how the tests go, this will also allow me to test how much common mode chokes are needed to "strangle" the data too much, since i can just daisy chain them
OK, I think you use "isolate" in the wrong way in this context. I think you mean buffer. A ground loop can not be eliminated by adding a transistor... anywhere, anyhow... Isolation here usually mean galvanic isolation when it comes to breaking ground loops. If you think about it - adding a transistor don't break any ground... right!?
Your big "filter" caps are set on the Vcc i.e. power system of the sender and receiver circuits. Your title implies "filtering" - but as most of us would believe, it's not filtering of the signal but something else.
All quite confusing and non scientific... but high marks for the spirit... just don't educate without a warning badge...
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Your big "filter" caps are set on the Vcc i.e. power system of the sender and receiver circuits. Your title implies "filtering" - but as most of us would believe, it's not filtering of the signal but something else.
All quite confusing and non scientific... but high marks for the spirit... just don't educate without a warning badge...
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thats why i said "isolate" ... tho just think about it... a cable has under 1 ohm resistance... if you add a 333 ohm resistor you are essentially "isolating" ground noise, because it search another less resistance path, same goes for ground loops
100 ohm should give you in most situations 100-1000x reduction of ground loops... imo its pretty efficient in "isolating" tho you are right, its not true galvanic isolation...
Yes, to essentially "filter" the power line, i never said the caps are for filtering the data lines, thats what the common mode chokes are there for (+ ferrite beads), its a costeffective filtering solution imo
why filter? just search a RC filter calculator and put in 1,5F and 0,2ohm (cable resistance) ... it gives you a filter slope starting from 0-2Hz, essentially just letting DC trough
well essentially i just document my own thing here... im not a pro in electronics, so dont pinpoint me on things i say but imo i can call this thing "filter"