Blind test listening results by professional audio engineers in the Los Angeles area

[Deleted member 48726]

I think we all know that LEDs ruin the sound, no matter what color they are.

 

[IAtaman]

John isn't trolling, but I think he IS missing the concept of "first define the question to be answered by an experiment when designing it." The question to be answered (which was not disclosed to the participants because it would invalidate the experiment) was "Are experienced and professional listeners subject to the placebo effect?" And the experiment clearly showed that they are- totally unsurprising, but since we so often hear claims of immunity due to the claimant's "vast experience," this is a nice data point confirming the contrary.

Well, I thought many of the people critisisig the article, including Restorer John, were critisizing not because they found it inconclusive but becuase they found it to be predictible and banal, which is not incorrect in my opinion.

 

[fpitas]

View attachment 326317

Doggone kids these days and their gaudy LEDs!

 

[voodooless]

I think we all know that LEDs ruin the sound, no matter what color they are.

On the contrary. LEDs make excellent low-noise current sources and are often used in modern amps for this reason.

 

[fpitas]

On the contrary. LEDs make excellent low-noise current sources and are often used in modern amps for this reason.

I've used them to bias the current source for differential transistor amps for T3 telephony purposes. Evidently the red light disturbed the test techs, so they painted over it lol.

 

[dasdoing]

never ever shoot the messenger.

 

[Ricardus]

Well, Los Angeles, what did they expect...

The results would be the same with any group of people anywhere in the world.

 

[SIY]

On the contrary. LEDs make excellent low-noise current sources and are often used in modern amps for this reason.

Voltage sources (low impedance), not current sources (high impedance).

 

[voodooless]

Voltage sources (low impedance), not current sources (high impedance).

Nope:

Constant Current Sources for Audio Amplifiers

Website of Nathalie Beimler. Constant current sources for audio amplifiers.

nathaliebeimler.com

 

[fpitas]

Nope:

Constant Current Sources for Audio Amplifiers

Website of Nathalie Beimler. Constant current sources for audio amplifiers.

nathaliebeimler.com

He is right. Take a look at those schematics; the lamp is used as a voltage reference for the transistor.

 

[IAtaman]

Nope:

Constant Current Sources for Audio Amplifiers

Website of Nathalie Beimler. Constant current sources for audio amplifiers.

nathaliebeimler.com

In that circuit, LED is the voltage reference in current source . It is not a current source itself.

 

[Ken Tajalli]

Nope:

Constant Current Sources for Audio Amplifiers

Website of Nathalie Beimler. Constant current sources for audio amplifiers.

nathaliebeimler.com

SIY is right.
You can use a led to construct a current source.
Indeed SIY has a (if not mistaken) tube amp design, that uses LEDs to set bias on the output tubes.
Aptly, he called it red light district amp.

 

[voodooless]

Okay guys, I get it

 

[MAB]

Okay guys, I get it

Yeah, I know how you feel.

 

[Bugal1998]

Anyone (here at least) could see this one coming from a mile away. Zero surprise. Being a professional doesn't shield someone from bias effects.

Sure doesn't. Being an expert can make one even more vulnerable.

 

[Punter]

Don't know what issue anyone has with the "Red & Blue" LED test. I think it's very elegant and has a definite outcome WRT the listeners. The outcome neatly demonstrates expectation bias and self-generated perception in the subjects. I agree also with the sentiment that it takes a brave listener to declare "I hear no difference".

 

[voodooless]

Yeah, I know how you feel.

Yeah, well… my analog circuit skills are not very good to say the least. I know what the bits do on their own, but put together I quickly loose the grap, especially if transistors are involved It’s just not something I learned in any great detail.

Technically I wasn’t completely wrong though, so I’ll take it as a win anyway , especially since I (re)learned something again.

 

[kemmler3D]

You really have to experience this. Reading about it is not sufficient, hence I'm all in favor for doing this kind of test as often as possible.

+1. I haven't been subject to a surprise A vs. A test before, but I have found myself twiddling EQ / filter knobs in a DAW, definitely hearing a (small) difference, and then later realizing the EQ was disabled. I think this is a common experience among people that play with audio, and if you stop and think about what you just heard... nothing but your mind playing tricks... it's very humbling and eye-opening.

I don't know if there is a good way to spread this experience around. A Youtube video with comments disabled could work, but would it scale...?

 

[olieb]

and if you stop and think about what you just heard... nothing but your mind playing tricks... it's very humbling and eye-opening.

Well I guess it is a question of attitude.
Some people stop and activate routines of doubt and investigation.
Others move on and jump to conclusions.
Probably this cannot be changed easily.

 

[MattHooper]

Color affects mood, mood affects perception. That's the link.

I did find a study that used VR headset to change the color of a concert hall, and headphones. N=30 so big grain of salt. Red rooms sound best. Just like red cars are faster.

In general, red/orange/yellow give people energy and make them happier, blue/green/purple produce calm and mellow states of mind. So a color that helps for high energy music might detract from more mellow music, and vice versa.

Not my area of expertise, but makes sense to me.

I happily avail myself of such influences. Behind my stereo speakers is my large projection screen. Programmable colored lights shine on that screen, and I find it can enhance and influence my perception of the sound.