How (Not) to Decouple High-Speed Operational Amplifiers

[BrianL]

As Guido said, the ap-note has some glaring errors. Some
ap-note authors are more believable than others, even within
the same company. At times you wonder if anyone with
any smarts reviewed before publishing.

 

[Guido Tent]

Gentlemen:
I value your feedback on superE-cap's controversial topic.

I lack the knowledge and instruments to test the inventor's statement.
Until now, if I understood well, you provided solid arguments based on conventional knowledge about why this superE-cap magical decaying impedance is not possible.
Would it be too difficult to test it?

I appreciate your effort.
Kind regards
Mauricio

no need to test, can be easilly calculated with sufficient precision to show that the so called cancelation doesn't work.

So, it doesn't work, but sounds good......

best

 

[Joseph K]

Maxlorenz,

Only because You are insisting on to see experimental results: I have done measurements, based on a similar request from Kuei. I have to admit, I still did not do these measurements on real BG-s yet. I will have to find a good reason to make the necessery investment.. though I believe what is said, that they sound good.
But the only difference between BG-s and the standard caps is the double foil construct, which makes them non-polar, enabling to swap them around in the real setup with, say, 40 V DC present. As I had explained in those threads, for impedance / ESL measurement this DC is not needed, so you can freely experiment with standard caps in a Super E config. Now, if a BG is constructed half as good as a standard cap what regards ESL, then the conclusions reached by me are totally valid also for BG-s. If they are not behaving like normal caps, I would consider that a real defect, and a faulty product!
Here are the posts in this regard:

About bg superE

I would like to emphasise again my conclusion reached here

Also, if You follow this thread below [not so long], You can get an idea how hard it is to have an influence / modify on the original cap parameters:
[Even if the original idea is a WORKING one, which is lightyears distant from the blubber produced by those thiefs in the BG marketing division]

http://www.diyaudio.com/forums/showthread.php?s=&threadid=64748

So, please, could we stop here and not infect any more this otherways very good thread? And do not post any more BG marketing bullwaste-heap which just makes me womit? These texts are worse than certain television preachers.. with exactly the same scope: gimme more more money..

Finally I would like to add, that if anything, then the idea of Jneutron about wrapping /coaxing an AXIAL film cap [which DO show quite high stray inductance in real setups] is a REAL ESL killer, in other words, a real Super E config! I have gone down from the original 14nH to 6nH in that setup shown in the thread!

Ciao, George

 

[maxlorenz]

Before all, thanks to BrianL, Guido and George for your replies.

I will not disturb our beloved forum again with this topic. The thing is that I tried the superE caps and liked them and wanted to know why.
And I "invested" US$3.7 to discover it.
I will have to wait untill Christmas and see if I receive the needed equipment

Dear George:
Thanks for your link to the copper wrap idea
I will try it in my radial E caps and judge by ear, after all my country is one of the biggest copper producers

So, even if nobody has tested exactly the question on BG caps, as in the Mythbusters' show, inductance cancelation is "probably busted"

Gratefully yours...
Mauricio

 

[maxlorenz]

Dear Joseph K:
You got me intrigued with your copper foil advice. I re-read the explanations of Jneutron and caugth the general idea.

I tested it today with my Sanyo Oscon (100uF/10V) caps from my superDAC's digital PS. When I swaped the previous caps for the Oscon I found cleaner, more precise sound, but lack of midrange/midbass power. That annoyed me a lot.

I put a self locking copper foil to one of them and...am I going crazy or am I the most susceptible guy?
I heard more bass
Then I continued to dress other caps untill I went out of copper: 2 Oscon's and 1 Rubicon ZL from digital PS and 2 Rubicon's Zl from DAC's analog PS. I would swear I hear more robust presentation with details presenting in a powerful manner. Note that I don't know what kind of change the tweak is supposed to bring, if it ever works...

The truth is that now I feel confortable with the Oscon's as I still enjoy its useful strong points without the adverse effects that I noted.

I hope some will be interested to try this very cheap and potentially immediate tweak to clear out the doubt.

Thanks again, Joseph K
Mauricio