John Curl's Blowtorch preamplifier part III

[mountainman bob]

It is encouraging that healthy sense of humour survives up there on the mountains together with the ability to deal with reality.

George

‘Once one loses the sense of humor they are bound to finish their days seeking company for their misery’.
- MMB

It’s glaringly obvious here abouts 😀

 

[Joe Rasmussen]

My point is: it has to be blind.

There is something about that statement that bothers me. I wonder what it could be?

 

[Joe Rasmussen]

If you are asking people which sound/ketchup they prefer then you need to hide from them the identity of what they are experiencing...

I still don't see an equivalence between sound and ketchup. The whole point being made is that they are not. One is about fidelity and the other is not. I hear a triple-tracked acoustic guitar and not double-tracked, that is my criteria. Why do I need to go blind to hear that?

 

[DF96]

You need to be blind because what you 'hear' is influenced by what you see. If you expect Product A to allow you to distinguish a triple-tracked guitar from something else then you may 'hear' this when you know you are listening to Product A. This is not because you are dishonest, deaf or daft but because you are human.

 

[PMA]

JR - You have just shown ketchup-like reasoning, not high fidelity reasoning. I guess you do not understand why.

 

[dimitri]

Levinson JC-2 jacks

JC wrote:

Later, I found layout, (poor asymmetrical Xtalk) Cap supply bypasses (Tant) and poor channel separation due to a finite Z active buffer for the phono stage, and finally, the poor RCA connectors (the only ones really available at the time).

Here are some measurements. Red trace - RCA plug attached to the input RCA jack, yellow - after RCA plug rotation 90 deg back and forth in RCA jack (kind of cleaning)

Greetings to Simon

 

[PMA]

Why that much mains spuriae?

 

[billshurv]

Dmitri,


That's the best example I have seen so far to show why

a) I dislike RCAs
b) The old recommendation about replugging things every month or two was wise.

 

[PMA]

Must be a kind of a design flaw.

 

[dimitri]

Why that much mains spuriae?

External power supply has 5mVpp 180Hz on each rail. My understanding that internal DRF-2 power supply filter is dead (dry caps). The question on PSRR can be addressed to original designer.

 

[Max Headroom]

You need to be blind because what you 'hear' is influenced by what you see.

This is gross generalisation and cannot be applied to all circumstances.
For the novice audio enthusiast who is 'dazzled' by new gear, with short term audition in the hi-fi shop demo room perhaps this is true.
However, for those like me who regard any audio item as 'just another box' with 'one job to do' and especially in the pro audio world I hold that this is not true and ultimately 'performance talks and BS walks'.
So, for some participants sighted ABX testing will skew results but it is ultimately long term listening that proves preference and this is borne out by market opinion and market acceptance.

Dan.

 

[billshurv]

Must be a kind of a design flaw.

I would agree the RCA is a flawed design!

 

[hhoyt]

JC wrote:
Here are some measurements. Red trace - RCA plug attached to the input RCA jack, yellow - after RCA plug rotation 90 deg back and forth in RCA jack (kind of cleaning)
Greetings to Simon

And I will add to that excellent information how use of an oxygen excluding oil (almost any oil for that matter) can maintain adequately low contact resistance longer than the same connector pair dry.

Once the oil is applied, further mechanical scrubbing of the contact interface breaks through oxide layers to establish metal-to-metal contact. The presence of an oil seal around the contact points heps exclude oxygen, increasing service time for adequately low contact resistance.

2500 BNC connector pairs showing this characteristic can't be wrong.

Cheers!
Howie

 

[mmerrill99]

Lighten up, you just got punked by a John Lydon quote (Rise, 1986)

YouTube

Ah, I see - I didn't get the Sex Pistols reference - that's why it appeared incoherent & inchoate - a pretty incoherent & inchoate band as was most of punk

 

[mountainman bob]

This is gross generalisation and cannot be applied to all circumstances.
For the novice audio enthusiast who is 'dazzled' by new gear, with short term audition in the hi-fi shop demo room perhaps this is true.
However, for those like me who regard any audio item as 'just another box' with 'one job to do' and especially in the pro audio world I hold that this is not true and ultimately 'performance talks and BS walks'.
So, for some participants sighted ABX testing will skew results but it is ultimately long term listening that proves preference and this is borne out by market opinion and market acceptance.

Dan.

Yes......I really don’t understand how some believe bias cannot be ignored.

 

[billshurv]

And I will add to that excellent information how use of an oxygen excluding oil (almost any oil for that matter) can maintain adequately low contact resistance longer than the same connector pair dry.

Any recommendations on a readily available oil type for when my Deoxit runs out?

 

[Max Headroom]

Any recommendations on a readily available oil type for when my Deoxit runs out?

I heard you could try your Vaseline


Dan.

 

[billshurv]

I save the vaseline for crimped connections.

 

[Max Headroom]

Yes......I really don’t understand how some believe bias cannot be ignored.

Simple, because they have bias themselves, ie an agenda !.


Dan.

 

[mmerrill99]

Yes it seem that only one these diyaudio forums is a listening observation taken to be a claim of something rather than just one's listening observation.

And while some, like Evenharmonics, like to think of ABX's, and the like, as some kind of "proof" of something, I think they are just subjective listening observations relevant only to the context in which they were done.

Indeed

Where and when did you take the poll?

Maybe you don't understand common sense - did you miss this course in school? 😉

If ones cares to have a quick look at the threads started by Merrill and Jakob, two of which they were suggested to open due to them posting the same thing over and over again here iirc, it will become evident why they are back here posting the same thing over and over again.

Why not go elsewhere, then?

I think you really don't have a clue.

ABX or any form of DBT is essential for any audio product development.

Is audio development what is being done on audio forums when ABX 'proof' is called for?

It basically boils down to asking live human beings what they like best (after having determined that they do hear a difference, that is).

A preference test determines what they like best A statistically significant result encompasses the fact that they hear a difference ven though they might not be able to identify a specific difference & might believe they are just guessing.

The same approach is taken for mayonaise, soft drinks, dip sauce and female hygiene products, amongst others. People are asked what they like best, without knowing the providence of the product they are testing.

Yes, a preference test as I suggested What's your problem ?

The occurance of null results simply means that for audio, above a certain level ....... it is good enough, differences are no longer perceived, let alone that preferences can be developed.

As Jakob has pointed out many times already, ABX test is less discerning & less sensitive a test for small differences. That means there are more null results (than other tests results) even though there are audible differences identifiable using other listening tests

To me, it is incredible that people can believe that differences would automagically disappear under blind testing. How can they? How could my female hygiene product suddenly become undistinguishable from the competitor's version, once brandnames are removed?

Again you show ho wlittle you know & I see you backtracked with your reply to Jakob's post

Serious businesses, also in the audio industry, test blind. Some even publish the results of their findings. On the other hand, charlatans and snake oil merchants have something to hide, so they try to create a believe system that blind testing doesn't work.

Sure, the paranoia is palpable on many here

Yes......I really don’t understand how some believe bias cannot be ignored.

When people say they had "their eyes opened by ABX test" what do they really mean? Before they did the test they were sure they could hear a difference in sighted listening (so were suffering from a sighted bias influencing what they heard) After the blind ABX test when there was no difference discernible, now they do the same sighted listening & they cannot hear a difference? What has happened? Have they suddenly become immune to the sighted bias they were previously under the influence of? Or have they replaced one bias (belief of a audible difference) with another but contrary bias (belief of no audible difference)?