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OPA Alice: can 1 gig resister be replaced with a 750M ?

[email protected] All Messages By This Member #36382 I cant get a 1 gig ohm resistor but i can get a 750M. I can also series 2x 500M but that will complicate things and be difficult. >https://www.jlielectronics.com/content/OPABoardsREV_1.pdf Here's a schematic for reference thank you
Jules Ryckebusch All Messages By This Member #36383 开云体育 Yes a 750M will work. Anything above 200-300M will work. ?Actually 100M will work ?you start to get a 3dB down point in the audio range below 200M ? Best Regards, Jules Ryckebusch? toggle quoted message Show quoted text On Jun 5, 2024, at 14:22, denysrud via groups.io <denysrud@...> wrote: ?I cant get a 1 gig ohm resistor but i can get a 750M. I can also series 2x 500M but that will complicate things and be difficult. >https://www.jlielectronics.com/content/OPABoardsREV_1.pdf Here's a schematic for reference thank you
@jp8 All Messages By This Member #36384 Yes, you can, like Jules already said. But not only will the LF cutoff point move to a higher frequency. LF noise will also increase, because with every doubling of the resistance, the resistor's noise that will be shorted to ground through the capsule capacitance will double as well. The resistor's Johnson noise increases by the squareroot of the resistance, so the net effect is still a noise reduction. 1 G or higher resistors are abundantly available from Mouser an Digikey. A popular one is an axial type from TE Connectivity. Or search on Aliexpress. The smaller types on Aliexpress are mostly radial types. The axial types mostly large high voltage versions. Jan
[email protected] All Messages By This Member #36385 Ah great thank you
[email protected] All Messages By This Member #36386 @jp8 If I understand you correctly, the sum total of noise in the audible band is reduced with a larger resistor value, so I should try to get 1G if possible. Unfortunately there's some availability issue where i am. So getting 1G is a bit of an extra amount of work. For aliexpress, I am concerned about quality. I am not very experienced so I want error potential to be low. so i think im gonna go with the 750M, and hope the extra noise wont be noticed by me. thx again
@jp8 All Messages By This Member #36387 Yup, your understanding was right.? But of course, you could still first try 750 MOhm and only if you're not happy with the LF noise, then try to get 1 or 2 GOhm resistors. The human ear is not very sensitive to low frequencies, so maybe you won't even notice. While I agree there are quality concerns when byuing stuff from Aliexpress, especially concerning audio ICs, I found some good quality GOhm resistors there that I'm happy with. 1GOhm: 2GOhm But these are not at all cheap, though... The cheap and popular TE Connectivity part is the RGP0207CHK1G0. Jan
Vladimir Matveyev All Messages By This Member #36401 It's going to work, but not as good. I have a friend who is an electronics expert who said that even 1G resistor is actually not too good and it is recommended to use even higher value resistor. It has something to do with overal noise etc. I'm not sure as I am no expert, just that I've been told.
Jules Ryckebusch All Messages By This Member #36402 开云体育 The one gig is pretty much “industry standard”. The capsule capacitance swamps the LF noise it can generate. You could easily go to 2G at 10G you can run into humidity issues and other fun stuff. ? Best Regards, Jules Ryckebusch? toggle quoted message Show quoted text On Jun 8, 2024, at 19:06, Vladimir Matveyev via groups.io <depeschzeu@...> wrote: ?It's going to work, but not as good. I have a friend who is an electronics expert who said that even 1G resistor is actually not too good and it is recommended to use even higher value resistor. It has something to do with overal noise etc. I'm not sure as I am no expert, just that I've been told.
Vladimir Matveyev All Messages By This Member #36404 Oh. would you please tell a bit more about 'fun stuff' you mentioned. It is interesting.

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