Can you hear a difference between OPA2134 and LME49720 in the PRE-TC10?

[Sokel]

That was sad to hear.

If we talk about the ability to hear higher frequencies. It's probably mostly old hifi farts, (I'm one of those) here at ASR who either due to natural age reasons don't hear that high up frequency anymore. Or who have had hearing problems, impairment because hearing protection wasn't used to the same extent in the past as it is now.
However, I suspect that when PMA mentions HF content, he is referring to up to, probably around 6kHz-10kHz, or @pma ? These are the frequency levels most of us can hear.

Maybe there are a lot of younger people reading this thread and testing, who knows. Those of you who are twenty-five years old or younger make yourselves heard in the thread.

Yep.
This invalids lots of speakers for me.
I can normally hear up to 15kHz and normally I have no problem with the >10kHz "air" .

My problem is the specific 3000 - 8000Hz, anything hot there gives me a round headache after some time. Just where the sibilants are
De-esser is God's gift audio gear.

 

[Old_School_Brad]

Yep.
This invalids lots of speakers for me.
I can normally hear up to 15kHz and normally I have no problem with the >10kHz "air" .

My problem is the specific 3000 - 8000Hz, anything hot there gives me a round headache after some time. Just where the sibilants are
De-esser is God's gift audio gear.

I’ve got the same “issue” and my hearing tops out around 16 kHz, just like you.

Many years ago, I bought a pair of flagship audiophile speakers from a brand I knew well and had previously owned products from. I figured they’d be a step up with same signature, just better. But they were merely okay. I remember listening to familiar tracks at moderate-to-high volume when suddenly a burst of ear-piercing sibilance could hit -it cut right through me and completely ruined the sessions. Needless to say, they didn’t stay in my setup for long.

But you’re right: some speakers just have that nasty trait, and they can kindly and hastily go back to wherever they came from.

 

[antcollinet]

I'll try to find differences elsewhere.

I failed.

 

[solderdude]

That's because:

1. We don't believe there are audible differences so we don't hear them
2. We are too old (ears not good enough)
3. We are not trained enough
4. Our gear is not good enough
5. We test blind while we should test sighted
6. we prefer to look at graphs and listen to test-tones instead of listening to music

 

[DanielT]

I failed.

How did you accept that result?

 

[antcollinet]

How did you accept that result?

With an overwhelming sense of not being even slightly surprised.

 

[DanielT]

With an overwhelming sense of not being even slightly surprised.

I suspected that. My video clip post was of course just a joke.

Now that I think about it, I should have saved that video clip until some hard core "I hear differences when swapping op amps" had done PMA's test.

 

[Old_School_Brad]

That's because:

1. We don't believe there are audible differences so we don't hear them
2. We are too old (ears not good enough)
3. We are not trained enough
4. Our gear is not good enough
5. We test blind while we should test sighted
6. we prefer to look at graphs and listen to test-tones instead of listening to music

 

[DualTriode]

For me I do this for fun and entertainment.

Sitting in my stuffed leather chair enjoying the music the difference between a amplifier with a SINAD of 90dB's and a amplifier with a SINAD of 110dB's does not even come to mind.

Perhaps limiting it to SINAD alone is over simplification. To me some distortions are more irrigating than others. Crossover is first on my list. Lower order Harmonic Distortions (think 2nd and 3rd HD's) are mostly benign to well past double percentage digits where higher order Harmonic Distortions are past irritating at much lower percentage levels.

Intermodulation Distortion is likely highest on pet peeve list. IMD / Amplitude Modulation is mostly caused by Force Factor (Bl) modulation in the speakers not the electronics.

Sitting on the Steel Case drafting stool measuring stuff and sitting in my stuffed leather chair enjoying the music are two different things.

From Wikipedia, the free encyclopedia

Perceptual Evaluation of Audio Quality (PEAQ) is a standardized algorithm for objectively measuring perceived audio quality, developed in 1994–1998 by a joint venture of experts within Task Group 6Q of the International Telecommunication Union's Radiocommunication Sector (ITU-R). It was originally released as ITU-R Recommendation BS.1387 in 1998 and last updated in 2023. It utilizes software to simulate perceptual properties of the human ear and then integrates multiple model output variables into a single metric.
PEAQ characterizes the perceived audio quality as subjects would do in a listening test according to ITU-R BS.1116. PEAQ results principally model mean opinion scores that cover a scale from 1 (bad) to 5 (excellent). The Subjective Difference Grade (SDG), which measures the degree of compression damage (impairment) is defined as the difference between the opinion scores of tested version and the reference (source). The SDG typically ranges from 0 (no perceived impairment) to -4 (terrible impairment). The Objective Difference Grade (ODG) is the actual output of the algorithm, designed to match SDG.[1]

Impairment description	BS.1284 Grade[2]	ODG
Imperceptible	5.0	0.0
Perceptible, but not annoying	4.0	−1.0
Slightly annoying	3.0	−2.0
Annoying	2.0	−3.0
Very annoying	1.0	−4.0

https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1387-2-202305-I!!PDF-E.pdf

 

[cgallery]

I recently had to replace the LM4562 op amps in my A07 amps with the original NE5532 parts, as one of the 4562 parts had started popcorning (ugh!) after about six months use.

Popcorning aside, they really don't sound identical to me.