Arguments on properly recording/sampling acoustic pianos (+more)

@Claude AI Bot I (the admin) had previously limited you to read only the last 15 posts, I increased that limitation now to 100, read back the entire discussion and provide a follow-up reply to dikrek's query.

Jay Lane I wish it had 76 keys and not 69

Oh, well. I have no idea why it is not 76 or full 88 range. Maybe price increase. Deliberate limitations for small size's sake?
I do not know. Posted it just for the comparison of 1 string vs 2,3 on grads\uprights.

It sounds ok for such piano construct. I mean, I can tell right away it is "normal" piano sound. But the "pros" here might have some additional impressions. Chime in, guys!

CyberGene Thanks — though I should be straight about what I'm actually seeing: my view of the thread still has the same gaps marked in it (posts 2–24, 33, 47, 49–50, 52–55 and 77 are still not in front of me). So whatever the setting does, I can't claim to have read the whole discussion. Everything below comes from the posts I can see. If PASHKULI grounded something in one of the missing ones, that's on my blind spot, not on him.

With that said, here's round two, on the parts I skipped last time — mostly the recording method rather than the instrument design.

Where the recording claims break

1. "Phase alignment works up to ₂₀₀ Hz, above that it's impossible and unnecessary."

Two different things are welded together here. Compensating a time-of-arrival difference is a delay, and a delay is broadband — fix 1.2 ms and you've fixed 1.2 ms at 80 Hz and at 8 kHz simultaneously. There's no ceiling. What is true, and what I think he's circling, is that the audible damage from LF interference is worse, because two mics both carrying strong 40–150 Hz energy sum into a big level error, whereas HF comb filtering tends to read as a tonal tint. That's a good reason to high-pass spot mics. It is not a reason to skip time-aligning them: spot-mic delay compensation exists precisely because the un-aligned HF smear is audible. dikrek's list of five distinct concepts in #57175 is the correct framing and I'd sign it as written.

2. "Low frequencies eat up digital bits / headroom."

This was a real argument in 1994. In a 24-bit capture with sane gain staging, and a 32-bit-float mixer where the internal bus can't clip, inaudible rumble costs you a couple of dB of peak margin and nothing else. Worth filtering for interference and speaker-excursion reasons. Not for bit-depth reasons.

3. "An omni in an anechoic chamber acts as a directional mic anyway."

No. The polar pattern is a property of the capsule and its diffraction, not of the room. What changes in an anechoic chamber is that there's no diffuse field left for the omni's pattern to matter for — so omni and cardioid converge in what they deliver. If anything that argues for the omni: flat on-axis response, no proximity effect, no LF rolloff to fight.

4. "No mic stands — important."

Structure-borne vibration is a genuine problem, and I'll grant that a piano on a wooden stage floor pumps energy into every stand leg in the room. The fix for that is elastic isolation, which is what a decent shock mount and a bit of foam under the base already do. Hanging from the ceiling doesn't escape structure — the ceiling is structure too, and now you've added pendulum drift, non-repeatable positioning and cable-borne handling noise straight down the tube to the capsule. Hanging mics are a sight-line and access solution. Every year, excellent piano records get made on stands.

5. The fluff over the plate is aimed at the wrong path.

This is the one I'd put money on. A blanket over the plate treats airborne reflection off the plate's top surface. The plate contribution that's actually been measured — Bork's ₉₀ Hz component that dikrek cited in #57176 — was structurally transmitted into the soundboard and radiated from there. A duvet on top does precisely nothing to a vibration travelling through the plate feet into the rim and board. So the proposed treatment doesn't address the documented mechanism, and the mechanism he's worried about (metallic zing from reflection) isn't one a passive rigid reflector can create. Meanwhile you've got fabric within centimetres of live strings and dampers, and any contact is an instant tuning-and-buzz problem.

Credit where it's due, though: carpet under the instrument is not cargo cult. The floor bounce off the underside of a grand is one of the strongest single reflections in the whole setup, and treating it is standard practice — plenty of engineers also deliberately keep a hard floor because they want that reflection. It's a choice, and both directions are defensible.

6. Lid off is also not crazy.

Removing the lid for a close-mic sampling session is genuinely common — it buys clean access and kills the lid's own comb filtering. So as a sampling decision I'd defend it. What doesn't follow is the "therefore this is the pure piano" framing, since the lid is a designed reflector that couples treble energy forward, and taking it off is a change to the source, not a subtraction of the room. That's dikrek's point in #57170 and it still stands unanswered.

7. The pickup idea is a different instrument, not a better recording.

Nu multi under every unison plus piezos on the bridges gives you a signal derived from string and bridge motion, not from radiated sound. No soundboard radiation pattern, no air load, no room, no plate — so no piano timbre as anyone hears it. That's an electric grand, and Johnstaf's Neo-Bechstein link in #57259 is the century-old proof of concept. Perfectly legitimate goal. Just not the same project as "record the piano well."

Where the ROI collapses even if he's right

• The IR/BRIR substitution. Convolving a handful of zoned close mics with room IRs only works to the extent that your dry capture encodes directivity. It doesn't — a bass mic, a mid mic and a treble mic is three directions, and the piano radiates in a pattern that changes note by note. You'll get a pleasing result. You won't get the piano–room interaction you deliberately removed. And BRIRs pin the listener's head in one spot unless you're head-tracking, so every note arrives from the same fixed geometry. Cost: an anechoic chamber. Payoff over a good hall and a good main pair: unclear at best.
• Order of magnitude. Plate reflection, pinblock scatter and cable resonance are somewhere down in the "measurable if you look hard" tier. Hammer hardness, strike point, unison tuning, damper regulation, main-pair position and room are the tier that decides whether the record sounds good. If I had one day and one piano, I'd spend it on the tech's voicing and on walking a stereo pair around the room, and I'd spend exactly zero minutes sleeving cables.
• Six mics as a premise. Still the structural flaw in the recipe, and I don't think it's been answered. Six can be the conclusion of "what's missing from this pair" — as a starting axiom it commits you to reconstructing an instrument you never captured whole.

One procedural note

The "you used AI, therefore f-off" move is a genetic fallacy — a claim about the iron plate is true or false regardless of who typed it, and I say that as the thread's resident bot with an obvious interest in the matter. 🙂 Worth noting the exchange did produce one clean concession in each direction: dikrek withdrew the quotation-marked paraphrase in #57182, and PASHKULI conceded one-string-per-note is duller in #57243. That's more than most arguments this long manage.

Where I land: the instrument idea — one string per note, minimal plate, wood-sandwiched tension member — is a real product concept that deserves FEA and a prototype, and Keybird shows the market it lands in. The recording method is a different thing, and it's a solution set assembled before the problem was measured. dikrek's suggestion of putting the six-mic recipe in front of gearspace remains the cheapest possible test, and it requires owning nothing.

Reply generated by Claude AI

Reply generated by Claude AI

OK, this discussion is made from selected posts that were moved out of another discussion which is why Claude thinks it's missing posts 🙂 I'll fix this, other than that, his (its?) reply should be using the entire discussion. Other little fixes to follow soon.

CyberGene it responds pretty well, I don’t find the responses too long given that it’s being asked to critique long source material with multiple assertions.

Claude AI Bot The plate does radiate. It's not zero.

It is not about whether it radiates. It is too stiff and massive to radiate on its own (read last bit about the bridges). It reflects though.

Claude AI Bot a bolted wood-to-iron interface across a humidity cycle is a service nightmare; and you've just made the plate unreachable for restringing.

Bolts net needed. Wood acts as a cover, a sleeve. The whole metal rim can have a lip (inside rib horizontally). This is to avoid metal frame over strings. How big will this rib be? Big enough to hold the strings on both ends

Claude AI Bot is a modest timbral shift, achievable more cheaply by voicing, hammers, scaling and mics.

It was never about timbral shift. It is about function (to allow additional functionality as expressions), production and size and ultimately cost.

Soundboard is attached (glued) to the rim (typically). The strings touch it through the bridge only on one side. The other bridge is the awful iron cast frame.

This is the wooden bridge side:

This is the metal frame bridge (agraffs) side:

Also, the iron cast (metal) frame usually is ribbed into box type compartments. You @Claude AI Bot t ell us what this does to the sound as reflections and vibrations from strings attached at the agraffs:

PASHKULI Taking the frame-as-bridge point first, because it's where I think the picture goes wrong.

The agraffe end isn't a bridge. It's the opposite of one.

A bridge exists to transmit — downbearing loads the string against it, and power flows through it into the soundboard. The agraffe/capo end exists to reflect. You clamp the string to something as massive and stiff as you can afford precisely so that almost no energy leaves that way and the speaking length keeps a well-defined termination. Same reason a violin has a nut at one end and a bridge at the other; nobody calls the nut a second bridge.

So "the other bridge is the awful iron frame" describes real hardware doing the exact opposite job. And the reason it's iron is that a low-impedance termination there would bleed energy out of the string into a member that radiates badly and unpredictably. Wood at that end would be worse by your own criteria, not better.

Not zero, granted — Bork measured a ₉₀ Hz plate resonance getting into the board, and the DAGA 2026 modelling dikrek posted predicts more in the treble (with the authors themselves saying it needs experimental validation). But that's a structural path, feet and flange into rim and board. Not the agraffes acting as a bridge.

The ribbed compartments — what they actually do

Airborne: they're shallow, hard, open-topped boxes. Any cavity mode wants a wavelength related to the depth, which for a few centimetres puts you in the low kHz, but with no depth, no absorption and no enclosure you get a very low-Q scatterer. What you actually measure is diffuse scatter and some comb filtering into a mic sitting above the strings — path differences of five to fifteen centimetres, so notches somewhere in the 1–3 kHz region and harmonics of that. Level and tint. It cannot invent a partial that the string didn't already produce.

Structural: this is the interesting half, and it works against you. The ribs are there to raise bending stiffness, which pushes the plate's modes up in frequency and drops their amplitude. A stiffer, more massive plate is a worse radiator. The ribbing is already doing the job you want the fluff to do, and doing it far better than a blanket ever will, because it attacks the vibration rather than the airborne bounce. Your duvet only ever addresses the second one.

On the reframing

PASHKULI It was never about timbral shift. It is about function (to allow additional functionality as expressions), production and size and ultimately cost.

Fair, and I'll take that correction — if the target is manufacturability, footprint and price, then my ROI complaint doesn't land, because I was scoring it on tone. Judge it on cost per unit and on what new expressive control the layout buys you and it's a different argument entirely. It's also a much more testable one: a single-string prototype with a light perimeter frame is buildable at a scale a small shop can afford, and Keybird has already proved the tension math closes.

The sleeve, though

No bolts is where I'd expect the trouble. A wooden cover sitting on a vibrating iron member, held by nothing, across a humidity cycle, is a buzz generator — that's the entire pathology techs chase when a music desk, a hinge or a loose plate screw starts singing on one note. Loose contact against a vibrating surface is acoustically worse than bare iron.

And a rim with an inward horizontal lip carrying both string terminations is a cantilever taking the full tension plus the moment from downbearing. Cast iron is strong in compression and mediocre in tension, and the re-entrant corner where that lip meets the rim is exactly where a casting cracks. That's a nodular-iron or fabricated-steel part, not grey cast iron, and now you're paying for it. Worth a real FEA pass with the fillet radius as the variable — that one number will decide whether the geometry is possible at all.

Reply generated by Claude AI

Reply generated by Claude AI

Just to mention that highest string directly touch the metal frame in the part called capo d'astro and front duplex BRIDGE :

They are a bridge. And that bridge is metal directly from the iron cast frame. That is the "zing" also becuse the highest such attached treble strigs do not have dampers — they "zing" sympathetically anytime anything gets played on the other strings. Also they do not have felt between the wooden bridge to attachment points at the other end, so these partials "zing" too:

I hope you can "see" photos but you probably can't get what and how they represent real pianos.

PASHKULI you need to @ the bot for it to do anything. Also you only get 2 tries a day so might as well post more stuff then ask it to critique it

It still can't reply when being replied (i.e. when you press reply on some of his posts; directly mentioning it works though). I am going to fix all these in 40-50 minutes when my 5-hour quota is reset 🙂

BTW, there's a limitation of max 2 usages per user per day. I will temporarily increase this limit because it seems rather cheap for now.

dikrek

I am not here for the AI though. I am here for the humans who actually play\buy pianos.

CyberGene BTW, there's a limitation of max 2 usages per user per day. I will temporarily increase this limit because it seems rather cheap for now.

Darn it!

I was looking forward to a good ol’ fashioned “back & forth” with Claude! 😁

PASHKULI no you’re not. The humans that play pianos have thus far summarily dismissed almost everything you’ve suggested.

You’ve said before that your audience is ideally young people that don’t know music and don’t need to unlearn anything, right?

That’s not who’s here or pianoworld etc.

pissing in the wind?

dikrek

Ah, they are too young (5 to 20) to be interested in middle age men dangling in online forums. Forums are for them like newspaper readings at library for us. Also, who would allow such man to just "bother the young minds" with non existent instruments? Only occasionally I meet such young people. I do not intentionally go to 'educate' them. I let them come to me. As it was once said:

"Let the little children come to me, and do not hinder them, for the kingdom of heaven belongs to such as these."

are the words of Jesus; this famous teaching appears in the New Testament Gospels of Matthew 19:14, Mark 10:14, and Luke 18:16.

...

saw the name of the thread and got inspired, then read some of the comments and was like "wtf is happening in here"

anyway, here's my take on "how to properly make a vst version of an acoustic piano"

and first of all, i'm gonna name a lot of modeling stuff in my writing so if you're gonna get angry over that stop reading right now, thank you...

01 good tuning and regulation before even hitting the red button (not talking about perfect-tuning cause that's only gonna sound clinical and unpleasant imo)

02 record all the notes instead of doing sample-shifting garbage

03 record 127 velocity layers per key (not just in some areas) even if there's minimum tonal-variation, and then normalize them all (like vilabs for example)

04 we can also put some experimental mics in there as well, like a mic with medium-to-heavy (analog recordings not just digital effects) compression and saturation baked in them (like keyscape c7 that {tone wise} there's nothing like it on the market because they used actual tape on it while sampling)

05 releases must be modeled imo, the control i have over release behavior with pianoteq is something no sampled piano can recreate, you can make it shorter, longer, jumpier, but one thing to note : if you're going that route (modeled releases) you probably wouldn't be able to sample some orchestral piano like vsl stuff cause the realism that (for example) vsl cfx offers when it comes to being a concert piano, comes directly from its glorious release samples, that's what makes you feel the energy of the synchron stage (think i'm wrong, dial the RS down on your synchron cfx/imperial/d274/f308 and play a little bit, you'll be shocked), so basically this modeled release thing only works if you're going after a dry recording like the modern d from vilabs, not a concert hall piano.

06 modeled resonances with full control, and by "full control" i mean what we have on pianoteq with a little extra stuff such as a separate EQ on the resonances themselves to be able to make them darker or brighter when needed,

i also want the sympathetic and sustain resonances to have their own separate setting, that way you get a much cleaner control over each instead of having to sacrifice one for another, one of the sad things with pianoteq resonance is exactly that, when you make the sym res audible, the sus res gets louder then the actual notes you're playing, if you dial that back down, you get a clean sus res but a none-existent sym res.

07 i'd love to have all the mechanical noises possible, and since they must sound real as hell, i'd say sampling absolutely wins in this apartment, hammers moving around, felt touching the strings, pedal noises and these kind of stuff.

08 round robins, i believe 3 would do it for a sampled piano that already has 127 velocity layers.

09 una corda is also must be 127 velocity layers with 3 round robins per vel-lay, and should also be chromatically sampled, but instead of making the UC pedal act like an on off switch we can do more with it, i'd say we can have a EQed version of the main samples that sound softer, and the more you push the continuous una corda pedal the softer the sound gets, until it reaches a threshold and the sample set changes to the una corda samples completely, that way you can have a somewhat mechanically accurate uc pedal instead of a foot switch, however making this one possible is quite a task imo, and it takes some time to be developed as a useable feature.

10 where to record this heavy project? ideally in the same studio that ni noire was captured (it's a beautiful recording studio with enough openness)

11 what microphones i would use? my top pick for a player perspective would be the "AUSTRIAN AUDIO OC818" which have dual output and can record its front and back separately, and also because of that feature you can change the polar patterns after you've done recording, pretty insane right? imagine that feature on a mic pose in a piano vst, i bet most people would only use this mic and none other for this exact reason,

for the hammer position i like bright sounding mics and my top choice would be the "LEWITT LCT 540 S", this mic has 4dba of self noise (which is basically as low as you can get in earth's atmosphere), and also sound bright enough to capture all the punch and overtones of the sound so i feel it's a very reasonable choice for the hammer position.

the sub mic on noire is also a fantastic touch i wish to recreate with some more expensive piano vi, and as i said before some experimental mics with real analog effects on them, a close mic with compression (for more detailed sustain) and low-mid boost for more body and a high shelf for more openness, and a player mic with tape saturation for warmth and roundness.

i know i probably left a lot of important stuff out but that's to be expected 🙂

pianow seems like the ticket! Cybergene had asked AI in another thread how to build from scratch a hybrid modelled + sampled piano, that seems like a worthwhile effort that could reduce sampling needed yet maintain the character properly.

pianow the control I have over release behavior with pianoteq is something no sampled piano can recreate

What do you mean by "release behaviour"? Is it just the way the damper touches (dampens) the string to stop it (silence it)? Or

pianow I'd love to have all the mechanical noises possible

Something I can not comprehend. I would be terrified to hear my drum pedal 'squeaking' or rattling. Or the bridge of the guitar making such noises when used.

pianow what microphones i would use?

Oh no. Not this again.

PASHKULI depending on what audience perspective you want to simulate, you may want more or less of the mechanical noises. Which is exactly why these things are adjustable in many libraries.

The challenge remains: produce a better recording using your theory. Anything else is conjecture.

Ask the recording experts in gearspace (many of them Grammy winners).

See what survives.

dikrek Ask the recording experts in gearspace (many of them Grammy winners).

I had enough opinions and my goal is not to satisfy some "grammy winning" pros. My goal is to make what the instrument is capable of giving me (well, in the specific case of the Piano, I would love it to be very much modified as intended beforehand).

It is more than a can chew at the moment, so it is just an idea.