Why did you divide the result in your sim?
Also could you explain how this noise measurement can help me?
I don't care if you come from CERN or LIGO, -290 dB needs proof. I'll happily read the paper(s) of such feats when they come to publication, though.
That's generally the nice thing about folks who are deep into this field -- they don't make the claims explicitly without showing their methodology.Heck, -160 needs proof, as that's enough beyond all the big players respective systems.
I would like to answer your question, but I don’t understand. What result has been divided.
As mentioned before, EC cannot cancel its own noise. Doing this should give exactly the same noise spectra for both versions, with and without 10 Ohm, if not, the EC it is not maximally tuned. The second reason is that you get your information at what level the noise of your 100 Watt Amp will be and thereby the theoretical measuring limit for the THD for a given bin width, still completely neglecting things like the own THD of the EC, etc, etc.
Hans
Richard Marsh showed a QA401 plot with the fundamental notched out. I meant to ask him how he did it because I don’t see that option on the QA menu.
Richard Marsh showed many outlandish measurement results over time, and never provided a full disclosure on how these results were obtained. Among these, his Panasonic VP-7722A ability to measure under -140dB THD (the instrument display limit) @1KHz using the internal DSP to extract the harmonic components from noise, with otherwise no obvious special setup. I have two of those Panasonic babies and never got under some -128dB (-112dB THD+N) with the same instrument settings. The 12dB gap (x4 times) is no small potatoes at these levels. My Rohde&Schwarz UPD analyzer with the B1 low distortion generator option is also limited to some -128dB THD (-114dB THD+N) over the internal loop. So I would take Richards claims with a bit of salt, until independently confirmed.
From where I sit, even with the noise gain technique, anything under -160dB needs a full setup description and independent confirmation to be trusted.
Last edited:
The results are divided by 8.87 and 10 respectively as shown at the top of the graph. What is the reasoning?
Also do you know how to remove the noise floor in the FTT? I could show some more useful figures if it wasn't in the way. I don't know how you made FTTs look like you showed before.
Last edited:
"Richard Marsh showed many outlandish measurement results over time, and never provided a full disclosure on how these results were obtained."
It was a picture of his screen Syn08 - the fundamental was removed. I don't know whether he had some other gear in series with the QA401 - I just need to ask him.
Cant comment on the other stuff - I honestly don't know.
It was a picture of his screen Syn08 - the fundamental was removed. I don't know whether he had some other gear in series with the QA401 - I just need to ask him.
Cant comment on the other stuff - I honestly don't know.
That's exactly the problem, nobody really knows how he got these and other results. Another example:
Claiming is cheap, substantiating claims not so much...
Its a different reference. dBV is referred to 1V, while dBr is to whatever is set as reference.
Example. You measure 1uV, that is -120dbV right. If I set the reference to 100mV, that 1uV is -100dBr.
dBr is often used with different fundamental levels while wanting to keep the result comparable. Although you sometimes also see dBc which is referred to the 'carrier' which normally is the fundamental.
Jan
The point is, you are obviously lacking basic knowledge. How are you expecting to be taken seriously by your peers and potential investors?
So far, you contributions were occasionally entertaining (although not in a positive sense) but as soon as the fun is over (and it is about to) the naked truth will appear in full light: you are a clueless wannabe that doesn't even care to use Google.
He is aware of the gaps in his understanding, asks questions and clarifications and wants to learn. We should be glad with a member like that, the first one I meet in over a decade here.
Jan
- Status
- Not open for further replies.