John Curl's Blowtorch preamplifier part II

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#85,762
Bonsai said:
So, the USA has Jack Bybee, but looks like the Brits have worse . . .

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The Australian authorities made them remove the differentiation - i.e. not allowed to sell the same product in different packaging and at different prices.
Our Oz friends will have the details, but its this kind of stuff I love about the place: zero tolerance for b.s. Would be great if places like the UK and USA would also step up to the plate on issues like this. Don't get me started on cosmetics either.
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Please don't get me started on how much lobbying has been done by certain industries to ensure good, solid, scientific public health policies are legally restricted. (I'm looking at you, supplements/homeopathic/etc industry)

But that becomes VERY QUICKLY POLITICS so I'll avoid it.

But, yes, FTC here does on occasion strike things down but many of our regulatory agencies are a bit hamstrung/underfunded to keep on top of that. And/or don't do good work (but that's universal to the human experience).
 
#85,767
jneutron said:
If they taste good to the dog such that they drink more water, then they do cool the dog's blood...it's just a roundabout way.


As to using a scope to directly view low millivolt signals, why not just make a little battery powered x10/x100 switchable preamplifier and use a lower impedance 2 meter long differential cable to the diff receiver built for the scope? That way, you up eliminate many test issues, like enviro noise and ground loop.

I imagine there may be some sort of expertise available just on this thread alone for designing one up. I could see quite a market for such a simple thing if it is not already out there.


John
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That's well and good, but a GPB3k scope should not do this. A US$600 Rigol is manifestly better the triggering ain't half bad either.

We are in the same territory as those damn Project turntables that hum like buzz saw because of motor vibration mechanically coupling up onto the platter. The fix? You buy a GPB 25-00 noise reduction kit from the supplier.
 
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#85,769
Bonsai said:
That's well and good, but a GPB3k scope should not do this. A US$600 Rigol is manifestly better the triggering ain't half bad either.

We are in the same territory as those damn Project turntables that hum like buzz saw because of motor vibration mechanically coupling up onto the platter. The fix? you buy a GPB 25-00 noise reduction kit from the supplier.
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Some assembly required.
 
#85,771
Bear
At CES , what 6 yrs ago? Bybees demonstration of their music rails on the VMPS towers , in the in/out in/out demo, there was a very clear and cleaner audible difference in THAT system
Went back two seperate days and the same impression
Never owned or heard anything else from him however
Anyone who heard it and could not tell the difference,? needs to go home to mother..,

Regards
David
 
#85,774
Jakob2 said:
Were you looking for a scope that works down to 1mV/div?
I don´t know if other specs need to be "special" too, but the Hameg/RS entry line scopes might be worth trying.
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Until it broke I had one that went to 50uV/div at lower frequencies, an old Navy edition of a smaller modular Tek analog scope.

My ailing 2236 does 2mV/div, which is rarely usable with the high noise environment I'm in. I routinely use battery powered preamps when needed. I have a 485 as well in reserve.

But I was referring to the vibration fix kit for the turntable mentioned.
 
#85,776
AVWERK said:
Bear
At CES , what 6 yrs ago? Bybees demonstration of their music rails on the VMPS towers , in the in/out in/out demo, there was a very clear and cleaner audible difference in THAT system
Went back two seperate days and the same impression
Never owned or heard anything else from him however
Anyone who heard it and could not tell the difference,? needs to go home to mother..,

Regards
David
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20+ years, probably.


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But again I am trying to impress the frenzied masses here, it makes ZERO difference (to me anyhow) what is making "a difference" if that difference is in my opinion - and by extension, if you were there or doing the same thing(s) - A DIFFERENCE.

Bybee or a can of DUH. No difference.

What I'm interested in is IF you heard it, CAN it be measured, and if so, what was measured and HOW MUCH DIFFERENCE (all the known parameters, sure) is it??

Let's try to at least get a band of "fuzzy" where maybe a few people at least can agree that it is perhaps, maybe, likely that something in this abstracted and conjectured "band of parameters" or single parameter IS AUDIBLE!!

I'm suggesting to consider FIRST something that someone, anyone, and as many as possible HAVE PERSONALLY HEARD TO APPEAR to alter the sound. Then let's try to see if there are any published tests or individuals with advanced measurement gear that can suggest the measured differentials!!

If this isn't a reasoned and "scientifically based" approach, what is??

So far a whole lot of posters seem to be saying that nothing much alters the sounds unless there are gross differences in R, L & C or THD? And for THD I'm hearing numbers from 1.0% down to 0.000x% are being where that threshold lies.

I think the term here is: Quantify

Quantify what parameters IF changed (by how much, therefore the threshold is identified?) will NOT cause any audible difference(s).
Or, if you prefer, take something that at least appears to reliably cause a change in sonics, and QUANTIFY whatever is possible as the DIFFERENCE between IN and OUT.

A reasoned approach.

Many folks with advanced test gear here, ought to not be terribly difficult or complicated to achieve?
 
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#85,778
Bear, that's the issue--if you can hear it, that's great. But can you *reliably* do it? There are so many confounding factors that might affect that. If you can *reliably* hear it with as many confounding factor mitigated, then grab every possible measurement equipment to figure out what's going on.

Cart and horses.

Likewise, you'd do well to read Olive's blog (I'm yet to read his book) to get some amount of data that you want.
 
#85,780
bcarso said:
Audible things in order of importance:
Level differences
Frequency response differences
IM distortion differences
THD differences
Everything else

Yours to determine the weighting function applied.
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No need.
Not mine to determine.
I'm not a pundit, guru, researcher, or scientist involved in this field.

The question and the thing to apply to this list is the AMOUNT.

How much?

Then the thing to apply to the question is IF you have every HEARD a "difference" then how much difference(s) in these parameters were present??

Odd, that nobody has ever done this... very strange.

_-_-
 
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