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John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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Old 6th June 2018, 09:51 AM   #4991
billshurv is online now billshurv  United Kingdom
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John Curl's Blowtorch preamplifier part III
Suggest a test scenario. Cyril of course did but that was in a circuit where AC was dropped across the cap. All available at linearaudio to read.
 
Old 6th June 2018, 09:58 AM   #4992
Markw4 is online now Markw4  United States
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Originally Posted by BV View Post
If here is "no AC" (few mV) across coupling caps in circuits with impedance in kohm range, so no significant AC currents can be present.

Picture posted above is in real circuit in real use..
True, in that case. There could be other cases where large value caps are used to keep voltage low, but current is higher.

In the end though, if people can pass a good, reliable ABX test then it means there is a real effect by some mechanism. Likewise, if people can't pass a reliable test more people should would probably be willing to accept the results. Right now some reasonable people don't trust ABX testing and I think they are right in that there are a few easy to fix things that should be fixed and that should make a difference in test results. More small distortions should give positive test results if looping and one-button-don't-have-to-look A/B switching were implemented.

Last edited by Markw4; 6th June 2018 at 10:01 AM.
 
Old 6th June 2018, 10:13 AM   #4993
Markw4 is online now Markw4  United States
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Originally Posted by billshurv View Post
Suggest a test scenario. Cyril of course did but that was in a circuit where AC was dropped across the cap. All available at linearaudio to read.
I would like to see us make as much progress as we can by starting with better ABX and better DACs. For some reason, I don't know why there seems to be less of a problem with ADCs at high sample rates.

So, I would suggest people use the best soundcard they have to record the sound of their circuit with caps they think make it sound different and let's have a listen. With looped ABX more people will learn how to hear whatever is there in the recording. If enough hear something that may be reason to investigate more seriously. Sometimes that is how science works, an observation is made and a cause sought out. Other times science may work from theory towards efforts at experimental verification. Depends.

Unfortunately, I do not think there is a simple quick fix for resolving all disagreements about audibility. When a situation like that exists what we sometimes have to do is just start chipping away at it as we can.

Also, please recall we do have reports from credible people like Howie Hoyt who describe differences that are audible only in long term listening. I agree, my experience with that is about the same.

With better ABX I think we can get a better handle on some of those audible differences using short term testing.
 
Old 6th June 2018, 11:20 AM   #4994
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Originally Posted by anatech View Post
You have to know what you're doing and understand the circuit.
By example, it is well known, now, that polarized tantalum capacitors produce less distortions when DC+signal never goes under 0V.
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Old 6th June 2018, 11:24 AM   #4995
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ABX
ABX is too disturbing, ask too much memory efforts to give valuable results on subtle differences. AB is enough on my point of view.
And, if any difference is so difficult to figure out in a consistent way by simple listening tests, who cares about it anyway ? There is so many things that can be improved in any system first ...
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Last edited by Tournesol; 6th June 2018 at 11:35 AM.
 
Old 6th June 2018, 11:57 AM   #4996
billshurv is online now billshurv  United Kingdom
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John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by Markw4 View Post
I would like to see us make as much progress as we can by starting with better ABX and better DACs. For some reason, I don't know why there seems to be less of a problem with ADCs at high sample rates.
I think a start would be not calling it 'ABX' as there are many test protocols. Lets just call it 'Blinded testing' .



Quote:
Unfortunately, I do not think there is a simple quick fix for resolving all disagreements about audibility. When a situation like that exists what we sometimes have to do is just start chipping away at it as we can.
Agreed

Quote:
Also, please recall we do have reports from credible people like Howie Hoyt who describe differences that are audible only in long term listening. I agree, my experience with that is about the same.
But if he was peeking it just a report to potentially drive a test (and yes Howie is very credible). But you find long term listening not good and prefer superfast switching?


Quote:
With better ABX I think we can get a better handle on some of those audible differences using short term testing.
You said 'ABX' again :P
 
Old 6th June 2018, 11:59 AM   #4997
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John Curl's Blowtorch preamplifier part III
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Originally Posted by Tournesol View Post
And, if any difference is so difficult to figure out in a consistent way by simple listening tests, who cares about it anyway ? .

You seem to care about blocking capacitors despite no evidence that they actually are audible* for two working capacitors.



*note film types can cause a difference when glommed in by dint of larger loop area and pick up.
 
Old 6th June 2018, 12:25 PM   #4998
scott wurcer is online now scott wurcer  United States
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Originally Posted by billshurv View Post
*note film types can cause a difference when glommed in by dint of larger loop area and pick up.
This complicates the process a lot. What is a valid experiment that isolates one thing?
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Old 6th June 2018, 12:25 PM   #4999
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Originally Posted by Markw4 View Post
Also, please recall we do have reports from credible people like Howie Hoyt who describe differences that are audible only in long term listening. I agree, my experience with that is about the same.
How does that work? Simply please.
 
Old 6th June 2018, 12:31 PM   #5000
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John Curl's Blowtorch preamplifier part III
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Originally Posted by scott wurcer View Post
This complicates the process a lot. What is a valid experiment that isolates one thing?
Good question. I was starting from the position of a box with N* paths through it and 2N connectors so you have options of say
-passthrough
-Nasty electrolytic
-approved film cap.
The box should screen and if values are large enough then there should be no audible FR change.

I started thinking about switching with relays but then realised that we could easily fall down a rabbit hole of making it so that there isn't some charge time associated with the switch that might be detectable.


*Of course stereo pairs, but I would allow people to chose a different path for each channel in case they wanted to compare that way.

Last edited by billshurv; 6th June 2018 at 12:32 PM. Reason: LF removal
 

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