OPA2132 bypass

[Radian]

Hi,
I put this post in the chip amp forum because Carlos and some others mentioned using this OpAmp.
Please ignore any wrong grammar and spelling, this is my second language.
I have a very limited understanding of electronics, so forgive me if my questions seem to be silly.

I want to upgade my Marchand XM1 active crossover with the OPA2132.
As Carlos mentioned a wile back this is one of his favorite OpAms if it is bypassed with 47-100uf cap and a smal ceramic cap.
As I understant, this bypass is to be done on the negative and the positive rails of the OpAmp.
Each crossover bord uses three OpAms: one for the buffer and two for filtering. This makes all together 12 OpAmps for a three way stereo unit.
Since all the OpAmps are fed by one psu, do I need to use a cap after the psu with 12 times the requierd capacitence for one chip, or is it better to still have 12 induvidual caps close to the chips. The other question would be, if I already used plenty of capacitence for filtering at the psu, does that spoil the induvitual bypassing.

I appreciate any help,


Klaus

[peranders]

No worries about your english. It's good!

Good engineering pratice is to have 100 nF/63 V polyester or ceramic close to each supply pin of the opamps and down to ground. You can also have for instance 10 nF + 10 uF electrolytic capacitors but this OPA2132 or OPA2134 aren't so sensitive. It becomes more sensitive the faster the opamp gets.

Your last question: Strive alsways to have decouplings caps as close as possible to the "current consumer".

Doesn't your filter already have sufficient decoupling?

[Radian]

Thank you P-A

[carlosfm]

Originally posted by peranders
You can also have for instance 10 nF + 10 uF electrolytic capacitors but this OPA2132 or OPA2134 aren't so sensitive. It becomes more sensitive the faster the opamp gets.
....
Doesn't your filter already have sufficient decoupling?

Who told you so?
Just by looking at the datasheet?
Since I've registered here that I've been insisting on how these op-amps must be used.
The way you are "advicing" this member to use them they sound very bad.
Thanks for that.
This is also one of the major flaws of your "SMD Gainclone".
The way you use op-amps I should advice that the best results you can have is with the NE5532, they are very happy this way and when used this way they sound much better than modern and much superior op-amps.
Keep up the good work.
Oh, and please use the AD8620, a much inferior op-amp than the OPA2132, but sounds better the incorrect way you use it in audio applications, of course.

[macboy]

Who told you so?
Just by looking at the datasheet?
Since I've registered here that I've been insisting on how these op-amps must be used.
The way you are "advicing" this member to use them they sound very bad.
Thanks for that.
This is also one of the major flaws of your "SMD Gainclone".
...

Carlosfm,
Your post could have been more constructive. Instead of just telling others that you think they are doing something wrong, you could tell them how you think they are doing it wrong. That is, tell them what you think is the right way. You could have saved yourself a lot of typing by just saying, "In my experience, the OPA2132 sounds better to me when I used 100 uF bypass caps instead of much smaller ones.". That would be a constructive addition to the thread.

[moving_electron]

I'm trying some different op amps but keeping the same bypass caps before changing the cap values again.

OPA2132 sounds rather good to me and is the current winner with 47uF bypass caps per power pin. Has 22uf between rails though at a single point on the board and 22uF from each power rail to ground where power comes on board. Each has a 100nF ceramic as well. 100nf ceramic between each op-amp supply pin.

I may leave this bypassing alone for a while though as I am quite happy with it for now. Sounds good in the preamp and the phono preamp. Crisp, clean but not harsh or "clinical".

Other opamps to try though.

[Radian]

Hello Carlos,

Please tell me how you would go about in my case.
Since I have 12 OpAmps on one power supply do I still need to put 47uf close to each pin of the OpAmps or can I use 12X 47uf at the PSU and just 100nf close to the chips?
I actually don't have the 2132 but the 2134.

Cheers,
Klaus

[carlosfm]

Originally posted by Radian
Hello Carlos,

Please tell me how you would go about in my case.
Since I have 12 OpAmps on one power supply do I still need to put 47uf close to each pin of the OpAmps...

Yes.

Originally posted by Radian
... or can I use 12X 47uf at the PSU and just 100nf close to the chips?

No!

Originally posted by Radian
I actually don't have the 2132 but the 2134.

The same.
Enjoy.

[carlosfm]

Originally posted by moving_electron
OPA2132 sounds rather good to me and is the current winner with 47uF bypass caps per power pin.

You are getting there.
You are on the right path.
Take those 47uf caps and put just 100nf caps.
You will be shocked.
You will say: **** op-amp!

[moving_electron]

Originally posted by carlosfm


Take those 47uf caps and put just 100nf caps.
You will be shocked.
You will say: **** op-amp!

Are you saying to take off the 47uF and just use the 100nf caps?

My experience with the OPA2604 was that things got better as I added capacitance on the power pins although at that point I only had 10uF on them.

The OPA2132 sounded better to me than the OPA2604 when I tried them at 47uF. I made a number of changes to the system as I went from 10uF to 47uF.

Looking forward to being shocked! Mentally, not physically.