Master Thread: Are Measurements Everything or Nothing?

[Beave]

Did I mention that even though I'm 70, I have to keep resisting the advances from Sydney Sweeney?

Yesterday, on an entirely different forum, I learned that if you make a typo in her name, you get Sydneys weeney.

 

[MattHooper]

I’ve mentioned elsewhere my anecdotal experience of listening to a pair of small floorstanding speakers at my friends place, powered by a 300 B tube amp. I found myself intoxicated with the sound. In a way that I did not get from when they were hooked up to a Hegel solid-state amplifier.

I see that the amp has been measured, and since I’m not good enough at this stuff to confidently derive any conclusions, does anybody want to take a look at the measurements?

What I’m wondering is whether the measurements suggest that the amplifier could indeed result in audible colorations on a loudspeaker versus a good solid state amplifier.

SoundStageNetwork.com | SoundStage.com - Fezz Audio Lybra 300B Integrated Amplifier Measurements

www.soundstagenetwork.com

Excerpt:

—————-

Here we can see significant deviations of about 4dB from 4 ohms to no load through the flat part of the audioband (100Hz to 10kHz), reaching as high as about 6.5dB at 20Hz. This is an indication of a very low damping factor, or high output impedance. The variation in RMS level when a real speaker was used is about 3.5dB through most of the audioband.

To expand on the Lybra’s frequency response when using a real speaker, the chart below . . .

. . . shows the frequency response (relative to 1kHz) using a continuous sweep for the Focal Chora 806. Again we see deviations of up to 3.5dB within the audioband. It’s important to mention that deviations of this magnitude would be clearly audible, giving the Lybra amplifier a “sound” that would change based on the characteristic impedance curve of the speaker it’s connected to.

————-

Do folks here concur?

 

[sonitus mirus]

Yes, the measured frequency response swings clearly show that this amplifier will add coloration compared to a typical solid state design. Because it has high output impedance and low damping factor, the amplifier effectively forms a voltage divider with the speaker's changing impedance, causing level shifts by several decibels across different frequencies. These deviations, on the order of 3 dB or more, might be audible, potentially giving the amplifier a characteristic voicing that reflects the speaker's own impedance curve rather than simply amplifying the input signal.

 

[antcollinet]

What I’m wondering is whether the measurements suggest that the amplifier could indeed result in audible colorations on a loudspeaker versus a good solid state amplifier.

Yes, the measured frequency response swings clearly show that this amplifier will add coloration compared to a typical solid state design. Because it has high output impedance and low damping factor, the amplifier effectively forms a voltage divider with the speaker's changing impedance, causing level shifts by several decibels across different frequencies. These deviations, on the order of 3 dB or more, might be audible, potentially giving the amplifier a characteristic voicing that reflects the speaker's own impedance curve rather than simply amplifying the input signal.

Agreed.

But to further point out - the effect will vary dramatically from speaker to speaker depending on the speaker impedance curve - so one might "intoxicate" you, while another speaker might "drive you from the room with your ears bleeding"

You could get a similar effect with a solid state amplifier by putting a resistor in series with the speaker - though it woudnt match the exact frequency varying output impedance.

Or if you knew the amp output impedance plot, and the speaker impedance plot, you could perfectly simulate the response on a solid state amp using parametric eq.

 

[Mart68]

One thing to have a listen to someone else's system and be intoxicated.

Different when you listen to it every day and eventually the same colouration plastered across every recording starts to grate.

 

[goat76]

One thing to have a listen to someone else's system and be intoxicated.

Different when you listen to it every day and eventually the same colouration plastered across every recording starts to grate.

I don't think all types of coloration will necessarily give “sameness” to everything played, as different types of music and tracks will not have the same amount of energy over the frequency range.

Some coloration may just add that little extra that makes sense things sound more natural to someone’s ears, in a similar way as some people may like a little bit more energy in the bass than other listeners. That doesn't mean that the higher amount of bass will necessarily introduce “sameness”, it may instead just make most of the music sound more balanced in general to that person.

The amount of bass is just one example, it can as likely be other things like a BBC dip that takes off a little edge that makes things sound less fatiguing over time, or maybe an tube amp that technically may be inferior but brings the right type of distortion to everything for some listeners without necessarily making everything sounding the same, again because different music productions don't sound the same, to begin with.

 

[Mart68]

I don't think all types of coloration will necessarily give “sameness” to everything played, as different types of music and tracks will not have the same amount of energy over the frequency range.

Some coloration may just add that little extra that makes sense things sound more natural to someone’s ears, in a similar way as some people may like a little bit more energy in the bass than other listeners. That doesn't mean that the higher amount of bass will necessarily introduce “sameness”, it may instead just make most of the music sound more balanced in general to that person.

The amount of bass is just one example, it can as likely be other things like a BBC dip that takes off a little edge that makes things sound less fatiguing over time, or maybe an tube amp that technically may be inferior but brings the right type of distortion to everything for some listeners without necessarily making everything sounding the same, again because different music productions don't sound the same, to begin with.

I agree, it's not a one size fits all thing, sometimes it works - in the right situation and if it's subtle. A lot of the time, it isn't but it may still impress on a short audition.

 

[Blumlein 88]

If Matt wants to try it for himself pretty easy. Put a resistor of comparable value to the output impedance in series with his speakers. Then if it isn't quite the same, use Pkane's distort to add the same level of distortion. Should get you that sound if you find it intoxicated plus it can be switched out with ease if one desires it only on some occasions. I guess if you want to limit yourself to the intoxicating 15 watts at the 10% THD you'll need to restrict output levels with input voltage. So this amp not only changes FR an audible amount it probably has distortion with music that is audible too.

 

[MaxwellsEq]

I’ve mentioned elsewhere my anecdotal experience of listening to a pair of small floorstanding speakers at my friends place, powered by a 300 B tube amp. I found myself intoxicated with the sound. In a way that I did not get from when they were hooked up to a Hegel solid-state amplifier.

I see that the amp has been measured, and since I’m not good enough at this stuff to confidently derive any conclusions, does anybody want to take a look at the measurements?

What I’m wondering is whether the measurements suggest that the amplifier could indeed result in audible colorations on a loudspeaker versus a good solid state amplifier.

SoundStageNetwork.com | SoundStage.com - Fezz Audio Lybra 300B Integrated Amplifier Measurements

www.soundstagenetwork.com

Excerpt:

—————-

Here we can see significant deviations of about 4dB from 4 ohms to no load through the flat part of the audioband (100Hz to 10kHz), reaching as high as about 6.5dB at 20Hz. This is an indication of a very low damping factor, or high output impedance. The variation in RMS level when a real speaker was used is about 3.5dB through most of the audioband.

To expand on the Lybra’s frequency response when using a real speaker, the chart below . . .View attachment 417756



. . . shows the frequency response (relative to 1kHz) using a continuous sweep for the Focal Chora 806. Again we see deviations of up to 3.5dB within the audioband. It’s important to mention that deviations of this magnitude would be clearly audible, giving the Lybra amplifier a “sound” that would change based on the characteristic impedance curve of the speaker it’s connected to.

————-

Do folks here concur?

I always think of this as "the speaker is playing the amplifier"

The issue with this is that, with a sprinkling of luck, some poor-quality speakers may sound improved, but high quality speakers are all likely to have their accuracy degraded.

 

[solderdude]

If Matt wants to try it for himself pretty easy. Put a resistor of comparable value to the output impedance in series with his speakers

That output resistance may well be frequency dependent which would be hard to simulate with a fixed value resistor.

 

[DanielT]

Damn it. I will produce results! Everything must be measured.

The first test showed that according to his data sheet for his multimeter that the result was within the margin of error:

So what to do? More measuring equipment to solve it:

Then you can ask yourself the question, okay, but so what? If it's still not audible? On the other hand, why not measure if you have the instruments?
If he measures the contacts themselves or if it is a measure of how well he gets the cables there, I leave it unsaid.

Anyway, a good video for those considering the banana plugs that can be purchased through Soundimports when it comes to his testing of how well the cable attaches to the banana plug:

 

[Blumlein 88]

That output resistance may well be frequency dependent which would be hard to simulate with a fixed value resistor.

Well lucky for me I have no interest in simulating such an amp, but Matt may. Every SE tube amp, even a para-feed design like this one, was a circus-like caricature of the input signal. One could always use it as a preamp driver feeding a real power amp for the sound if one needs more than 15 highly distorted unruly watts.

 

[solderdude]

These tube amps are toys for (rich) boys and requires a belief system ....
Some seem to love them others don't care. To each their own.
I can't help but love Matt's persistence. I think he knows where ASR stands on this.

 

[antcollinet]

These tube amps are toys for (rich) boys and requires a belief system ....

I've described recently an audio show I went to which was basically a bunch of enthusiasts filling a hotel with their home systems. A massive mix from FOSI powered budget systems, through all the audiophile fantasies you could think of. I'd say roughly 30% tube powered.

Every room sounded different. But the differences between any two tube powered rooms, were just as significant as tube to solid state.

Or vinyl to streaming, or streaming to CD, or tape to vinyl, even cassette to digital etc etc.


I'm 100% convinced audible differences were all just speakers and rooms. Everything else was audibly undetectable when the speaker and room were also changing.

 

[Mart68]

I've described recently an audio show I went to which was basically a bunch of enthusiasts filling a hotel with their home systems. A massive mix from FOSI powered budget systems, through all the audiophile fantasies you could think of. I'd say roughly 30% tube powered.

Every room sounded different. But the differences between any two tube powered rooms, were just as significant as tube to solid state.

Or vinyl to streaming, or streaming to CD, or tape to vinyl, even cassette to digital etc etc.


I'm 100% convinced audible differences were all just speakers and rooms. Everything else was audibly undetectable when the speaker and room were also changing.

I missed your show report somehow. One year I went someone was attempting to use single ended valve power amps with some Focal towers and that didn't really work out, but otherwise you're right - speakers and rooms. Even vinyl vs digital front ends are at best a minor change.

 

[Wesseling Audio Lab]

I dont understand any, im not an engineer. However, i do believe i have some of the best ears and eyes in the business. My tragedy is that in most cases i pick apart sound and vision instead of enjoying the music and picture. Im always on the quest to find something better. Ive been buying and selling gear since i was 13 years old. I'm 52 now. Still searching and loving every minute of it. Thats why i love these sites and respect the opinions of all.
I love that Amir is into audio and takes the time to do this. I find it interesting.
To answer your question, what i do UNDERSTAND is the ARCAM AVR390 is better than any Denon receiver. I will never buy another Denon regardless of what any charts say.

"I dont understand any, im not an engineer. However, i do believe i have some of the best ears and eyes in the business."

"what i do UNDERSTAND is the ARCAM AVR390 is better than any Denon receiver. I will never buy another Denon regardless of what any charts say."

Not to take anything away from the fun of buying and selling gear

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If it measures right and sounds wrong, you're not measuring the right things.
If it measures wrong and sounds "right", you might be happy with what you hear but it's a lie.

The art lies in measuring the right things and having the sound reflect what's actually there. The task is tougher than it looks.

As Gloria Steinem said, "The truth will set you free, but first it will p*** you off."
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[Killingbeans]

What I’m wondering is whether the measurements suggest that the amplifier could indeed result in audible colorations on a loudspeaker versus a good solid state amplifier.

Yes, a glorified PEQ profile.

 

[egellings]

Likelihood is that the DACs are all pretty much dead flat in frequency response and have very low distortion & noise, so I would be hard pressed to hear a difference in them. Once measurements get very good, then getting better does not necessarily translate into better sound quality.

Asking for better performance would be akin to ordering a drop forge when all you need is a tack hammer.

 

[MAB]

That output resistance may well be frequency dependent which would be hard to simulate with a fixed value resistor.

The technical details of the impedance are unimportant. All that matters is that some frequency response coloration exists, even if barely audible.

 

[MattHooper]

I can't help but love Matt's persistence. I think he knows where ASR stands on this.

Ha! Totally.

Though to be clear, one thing I am not persistent about is asking any ASR member to believe implausible claims for which there is insufficient evidence. (Hence: mentioning anecdotal experience is not a plea for anybody to accept ideas they find technically implausible).

Asking questions like the one I’ve just asked about this tube amplifier arises because I find ASR very helpful for keeping my head screwed on straight and orienting my experience and beliefs within what is plausible or not.