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A video on testing the audibility of recording preamps

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Phos

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Jim Lill Conducted a variety of tests to determine if an expensive vintage preamp had the sound characteristics commonly ascribed to it. One highlight for me is that a (desirably) "slow" preamp has 300x the slew rate it needs to transparently pass a -0db 20K signal.
 
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I did not watch the entire video but recruited assistance from AI to view and summarize it with the following prompt:

Can you summarize the following video from the perspective of an objective audio scientist and sound engineer that fully understand the limits of human audibility and the equipment used to record and reproduce digital sound and music.

After reading through the notes provided, this is my own interpretation. The video shows objective evidence that clearly and repeatedly demonstrates that the legendary character people often credit to vintage Neve preamps is a myth; the signal is simply being made louder, not magically transformed.
 
He lost me at the point where he said every engineer he's worked with had console output at unity going into converters and therefore in order to prevent clipping the preamps would have been so low that they didn't distort, and then said that therefore driving preamps to distortion isn't a thing.

FFS, everyone tracks the way you track?

What an insanely stupid take. I don't even care if it's "mostly true", it's just such incredibly poor logic. Does he really think nobody cranks gain and lowers output to get distortion? Of course people do that.

The problems with videos like this is that a bunch of people are going to think now preamps don't make a difference, so when they go buy their half-rack unit they get "whatever" since it doesn't matter.
 
TK_IIVI said:
He lost me at the point where he said every engineer he's worked with had console output at unity going into converters and therefore in order to prevent clipping the preamps would have been so low that they didn't distort, and then said that therefore driving preamps to distortion isn't a thing.

FFS, everyone tracks the way you track?

What an insanely stupid take. I don't even care if it's "mostly true", it's just such incredibly poor logic. Does he really think nobody cranks gain and lowers output to get distortion? Of course people do that.

The problems with videos like this is that a bunch of people are going to think now preamps don't make a difference, so when they go buy their half-rack unit they get "whatever" since it doesn't matter.
Click to expand...
What, specifically, makes a difference in sound quality with a preamp? Can you provide some objective evidence? What are some things to look for to make sure it works as expected in any particular setup?
 
sonitus mirus said:
What, specifically, makes a difference in sound quality with a preamp? Can you provide some objective evidence? What are some things to look for to make sure it works as expected in any particular setup?
Click to expand...
All preamps will sound largely the same if not driven into saturation. Many preamps have output trim, so you can hit the output transformer really hard and get some saturation, but turn it down as it exits the pre so you don't overdrive your converters. Transformers are non-linear devices so hitting those hard would have to distort a signal so that it no longer resembles what went into the primary. Whether it sounds good or you'll like that is another matter.

A preamp manufacturer I know did a blind test where he used two different output transformers in one of his designs, and he fed the same signal into each over-driving the transformers. He put up various samples and you had to pick which ones you preferred. After we had done that he revealed that one of the transformers was a high quality clone of the API 2503 output transformer, and the Jensen equivalent. Jensen has this reputation of being super clean and very high quality. The overwhelming majority of the people chose the API transformer because it sounded much better when over driven. If I had to guess which was which before I knew which was which I would have guessed the opposite based on "reputation."

You can't always believe he hype.
 
Ricardus said:
All preamps will sound largely the same if not driven into saturation. Many preamps have output trim, so you can hit the output transformer really hard and get some saturation, but turn it down as it exits the pre so you don't overdrive your converters. Transformers are non-linear devices so hitting those hard would have to distort a signal so that it no longer resembles what went into the primary. Whether it sounds good or you'll like that is another matter.

A preamp manufacturer I know did a blind test where he used two different output transformers in one of his designs, and he fed the same signal into each over-driving the transformers. He put up various samples and you had to pick which ones you preferred. After we had done that he revealed that one of the transformers was a high quality clone of the API 2503 output transformer, and the Jensen equivalent. Jensen has this reputation of being super clean and very high quality. The overwhelming majority of the people chose the API transformer because it sounded much better when over driven. If I had to guess which was which before I knew which was which I would have guessed the opposite based on "reputation."

You can't always believe he hype.
Click to expand...
Thanks, that makes sense from a musical production perspective. In that aspect, overdriving a transformer seems like a valid creative tool. Though, as mentioned in the video, there are plenty of software plugins and digital modeling techniques that can perfectly recreate this overdrive distortion anyway. I think some people conflate studio tricks with home audio playback, when they really want a clean, transparent amplification.
 
Leaving aside phantom powered microphones and wireless microphones.

We can't make any universal statements about all dynamic microphones and all ribbon microphone sounding the same when feeding all mic pre-amps.

It's all about the input stage. But it's not about transformer overloading.
 
sonitus mirus said:
What, specifically, makes a difference in sound quality with a preamp? Can you provide some objective evidence? What are some things to look for to make sure it works as expected in any particular setup?
Click to expand...
I can't personally provide any objective evidence because I haven't collected any. But I worked in studios for about a couple of decades and routinely recorded both instruments and voice, mainly voice. Of course mic choice and placement makes a bigger difference choice of preamp, but they simply don't sound the same, in practice. Whether that's from noise, non-linearities or deliberate distortion is up for debate since I didn't keep track of that. All I know is that when going for some type of sound I reach for some devices and not others, because quite predictably I get a different sound that way.

It's really one thing to measure a preamp feeding it a sine wave and then comparing it clean versus literally clipping, and on the other hand feeding the device a complex signal. I also think it's true to say that if you have several different preamps and you push them to distort it's not only the amount of distortion that's evident but the way it distorts. In other words the generated distortion has a characteristic dependent on the device. And therefore, if you add the idea that we're not dealing with converters here, which hard-clip when reaching peak (ignoring soft-clip protection circuits), but instead a gradual onset of distortion, to me at least it seems entirely reasonable to say that while most mic pres may sound the same using good tools "properly" at nominal operating level the differences may appear at levels lower than the extreme ones that people use when testing, if we're using complex signals and not sine waves.

If you want clean then just get gear with a low noise floor and large dynamic range, and then just level match everything so it's operating within nominal range. If you do that you should be good, and probably nobody is going to care if you're using a tube amp or something else.
 
Have you seen the video? He tested with all kind of real music signals and used sine sweeps only to measure why he couldn't hear a difference between the Neve and the Focusrite preamp.
 
Tldr version. Recording engineers aren't all just looking for the purest signal path. So all bets are off vs a single specific use case.
 
LTig said:
Have you seen the video? He tested with all kind of real music signals and used sine sweeps only to measure why he couldn't hear a difference between the Neve and the Focusrite preamp.
Click to expand...

I watched part of the video. It's a real turn-off to me when the video is shot and edited to appeal to a certain audience, along with an 'idea' to get views. This format is nothing new, all it does is take an idea, pretend that everyone believes it is true, slap a catchy slogan on the thumbnail to get people to feel like they're now onto something new and revolutionary "People will be mad!" (why? because this guy has found THE TRUTH and is revealing it to you - you have been LIED TO all these years, but after watching this video you will know THE TRUTH). The editing is quick paced, the main character attractive physically as well as in that humble-brag ego-centric way, and it lets you feel like your fomo was unwarranted. You can now buy your $50 preamp instead of a vintage $1k unit and guess what, it sounds the same.

But be that as it may, I got to the point he was essentially saying that all recording engineers set output to interface at unity which means you can't drive the preamp input to clipping which means that there can be zero audible coloration as a result. That is not really good reasoning.

- Not all recording engineers use a console that is internally laid out that way.
- Not all recording engineers use a console that is internally laid out that way, that way (i.e. inserts and other components may exist before the output gain is reached, and they may track to tape rather than digital in which case a level that clips tape is desired in which case calibration throughout the entire chain would have to be considered)
- Most recording engineers likely do not use a console in the first place.
- A lot of modern music is going for "clean", and if he is then his personal experience is irrelevant.

and so on

In fact, particularly stupid was the insert of Ainlay as some sort of proof that what we saw is all that is happening at that session (on this topic) and that Ainlay always does this and that therefore this is what engineers always do. That insert was stupid.

In other words, I question his reasoning at this point.

Because of that I didn't go through the rest. I have better things to do with my life than to listen to another YouTuber explain how we have all been lied to and THE TRUTH has now been revealed which will lead to People will be mad!

Here's a video that actually does a comparison of a bunch of different preamps:


Note: I haven't watched the entire thing, but I saw the beginning of it and I listened to some of the examples toward the end of it.
 
I've seen many of Jim Lill's vid's.
He's a thorough ASR kind of guy but likeable.
Obviously, I hate him 'cos he plays guitar better than me (same with anyone else who does).

If you've seen his other stuff, he's a great myth-buster - there's a nice vid was where shows that there is no such thing as "tonewood" (beyond marketing) for example. Just like many other people who measure things would say, and who do proper comparisons - Glenn Fricker is another to look at, or to an extent, Paul Richards, luthier at Milehouse Studios.

Rant Mode On

The thing is I'm only ASR to see some objective reality. Sorry, but I can react badly to endless adjectives and adverbs (yes, adverbs are a thing!), that have been cut and pasted from internet searches or a lazy AI query. I may disbelieve what you say if you don't have test evidence... I can smell some of the Clevor Trevor (sic) weasels - you know, all those armchair experts and critics that have never used a 'scope, or designed hardware, or written a line of code, or played or recorded an instrument ! The "oh, but" time wasters! Luckily ASR is mostly sensible!

Rant Mode Off
 
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I like the video he makes as they of the kind of mythbusting which is also really needed in the "pro" side of audio, here is a LLM summary of it:

In his video "Tested: Where Does The Tone Come From In A Microphone Preamp?", musician and producer Jim Lill conducts a rigorous, scientific investigation into the legendary "tone" of high-end microphone preamps. Specifically, he investigates whether legendary vintage hardware—like a 1970s Neve console—actually delivers the "warm, fat, and punchy" sound widely attributed to it by the audio industry, or if affordable audio interfaces sound identical.

The video's findings and tests are structured across several key areas:

1. The Real-World Blind Tests & Mix Buildup [03:03]
Individual Tracks: Lill initially compares a high-end vintage Neve 31105 preamp module (which he bought for the price of 6 months' rent) against the built-in preamps of a cheap, basic audio interface. When recording guitars and drums, they sound virtually identical.

The "Mix Buildup" Myth: To address the common industry argument that preamp character "stacks up" across a full production, Lill records entire multi-track songs (covering delicate acoustic music, commercial pop, and heavy rock) one microphone at a time, splitting the signal to both preamps simultaneously. Flipped back and forth in a blind ABX test over 100 rounds, the results show he was essentially guessing [08:08].

2. Frequency Response & Linearity [06:32]
Using Room EQ Wizard (REW) to measure a full frequency sweep, Lill discovers that both the multi-thousand-dollar Neve and the budget preamp are completely flat—within a quarter of a dB of each other across the entire human hearing spectrum (20 Hz to 20 kHz).

3. The Distortion & Headroom Reality [08:26]
No "Subtle Compression": A step-response test reveals that preamps operate completely linearly until they hit their clipping ceiling. There is no magical "subtle analog compression" [09:17].

Voltage Math: Lill measures the actual peak voltage that common microphones output when tracking loud instruments (like kick drums or guitar amps), finding it maxes out around 0.97V [11:09].

The Clip Trap: For a Neve preamp to actually distort, it requires an input of 4.75V, at which point it outputs a massive 25.82V [12:29]. Because standard digital audio converters clip and distort at roughly 13V, it is mathematically impossible to clip a Neve preamp in a standard recording workflow without clipping the digital converters first [12:53].

Audibility of Harmonic Distortion (THD): Under normal use, the Neve's ambient distortion sits at -45 dB below the fundamental signal [23:23]. Through standardized Klippel listening tests, Lill notes that while human ears can spot distortion in pure sine waves at very low levels, auditory masking in actual music makes harmonic distortion completely imperceptible once it falls past -21 dB [22:43].

4. Slew Rate & Impedance [23:49]
Slew Rate: Often cited as the reason high-end preamps are "fast" or "slow," slew rate measures how quickly an amplifier can change voltage. Lill calculates that to perfectly reproduce 20 kHz (the upper limit of human hearing), a preamp only needs a slew rate of 2 volts per microsecond [26:04]. Oscilloscope testing proves the "slow" Neve easily achieves 8 volts per microsecond, making it four times faster than necessary [27:40].

Impedance: Testing various microphones reveals that differing input/output impedances alter frequency response by less than 1 dB, a difference barely audible in real-world contexts [29:31].

5. Testing the Holy Grail: Oceanway Nashville [32:51]
To eliminate any doubt, Lill takes his budget interface to Oceanway Nashville Studio A to test its legendary 1970s Neve 8078 console. Splitting identical live mic feeds between the multi-million dollar desk and his cheap interface yields identical sonic results [34:13].

6. Where the Tone Actually Comes From: The EQ [30:14]
Lill shifts the goalposts to show that the legendary "analog sound" associated with these consoles does not come from the preamps, but rather from their Analog Inductive EQs.

Analog EQs change their bandwidth (Q-factor) dynamically based on the amount of boost or cut applied (e.g., curves get narrower as you boost higher) [31:43].

Standard digital EQs do not inherently behave this way. However, by manually measuring the exact curves of the physical Oceanway Neve board, Lill writes a simple digital EQ plugin that clones those exact curves [38:00]. When compared back-to-back, the hardware console and a cheap preamp paired with the matched EQ curve are sonically indistinguishable [39:44].

Conclusion
Lill concludes that legendary producers and engineers have historically misattributed the great sound of classic records to their expensive preamps [35:00]. In reality, the tone comes from the engineers' skills and non-subtle variables: instrument choices, tuning, room acoustics, microphone selection, mic placement, and EQ curves [35:07]. Preamps simply make a signal louder, and affordable modern gear handles this task perfectly linearly.
 
Also, when the switch came to record digitally to files, as opposed to tape, noise suddenly became more of a thing - and all the expensive decks were OK with noise, but not all the cheaper players.
I know this because a friend of mine was a hardware design engineer for Soundcraft, (IIRC?) back in the day and was proud to design low noise circuits.
 
thewas said:
I like the video he makes as they of the kind of mythbusting which is also really needed in the "pro" side of audio, here is a LLM summary of it:
Click to expand...

LLM summary and information + technology = often fail.

TLDR most of it. Skipped to the last part:

thewas said:
Conclusion
Lill concludes that legendary producers and engineers have historically misattributed the great sound of classic records to their expensive preamps [35:00]. In reality, the tone comes from the engineers' skills and non-subtle variables: instrument choices, tuning, room acoustics, microphone selection, mic placement, and EQ curves [35:07]. Preamps simply make a signal louder, and affordable modern gear handles this task perfectly linearly.
Click to expand...

Sorry, but that's exactly the kind of rubbish I hate in these types of videos. I haven't heard a single engineer in my 25 years as a professional engineer attribute "the great sound of classic records to their expensive preamps". Not once. All of them have had a holistic view on it.

So this kid basically creates a strawman that doesn't exist and then argues against it.

Great for clicks. Bad for society.
 
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