Two hands on a live buffer

tap.scrub~ is the object in this library that most needs a controller attached before it means anything. Everything below assumes one: an XY pad, two faders, a trackpad, a phone sending OSC — anything that gives you two continuous values at once. The recipe is mostly about what to put on each axis and why.

Measured claims are borrowed from two hands on the same tape.

The chain

source ──┬─▶ tap.scrub~ ──▶ tap.palme~ ──▶ out
         └────── (its own dry path, via mix) ──────▶

The scrub records what passes through it, so it goes in the signal path rather than on a send — there is nothing to send it that it is not already hearing. Its mix is the dry/wet, and at mix 0 it is the input bit for bit, which means you can leave it in the chain permanently and have it be audibly absent until you touch it.

The pad

X is position, Y is pitch, and the whole object exists because those are independent. On tape they would be the same axis — moving the head is the pitch change. Here you can rake back through the last second and a half at the pitch you started at, or hold still and transpose, or do both at once in different directions. Spend the first five minutes doing each separately; the object does not become obvious until you have felt that they do not interact.

size is the texture control. 80 ms is a granular pad. Down at 20 ms it turns metallic and starts pitching itself at the grain rate; up at 200 ms it stops being granular and becomes a soft varispeed. Sizes that divide evenly by overlap have an exactly flat window sum — 80 with overlap 2 does — which matters when you want the still position to be clean.

overlap 1 is a texture, not a mistake. It leaves gaps between grains: a gated, chopped version of the same gesture. Worth a switch on the controller.

The honest bit about pitch

Transposing here warbles, and it is measured rather than apologized for: 98.8 % of a perfect shifter's energy lands within ±15 Hz of the transposed pitch (worst case 91.7 %), so the note is right — what the object loses is concentration, 92.0 % as focused as a clean shift and 75.0 % at worst. Audibly that is a warble, and it is the classic single-delay-line pitch-shifting artifact rather than anything peculiar to this kernel.

Two ways to work with it:

• Lean in. spray 30. trades the narrow comb for a broadband smear. On sustained material this reads as a texture rather than a fault, and it is the better answer for pads.
• Stay out of its way. Keep the Y axis to ±7 and let the position do the work. Small intervals warble least and the object is a scrub pad first.

If you need a clean shift, this is the wrong object — tap.shift~ is built for it. (tap.pitchaccum~ is built for shimmer rather than transparency, and has an open issue about where its line actually sits.)

Freeze, which is the other half

freeze 1 stops the recorder. The playhead keeps going, so the position now addresses fixed tape and the grains loop the same window — and you can still scrub, transpose, drift and spray through it. Nothing is going into the input any more, which is the point: it is a hold you can perform.

A sequence that works on stage:

1. Play the phrase through at mix 0. Nothing happens; the tape fills.
2. mix 100, freeze 1. The last few seconds are now the instrument.
3. Drag X slowly. This is the scrub.
4. drift -0.3. The playhead walks backwards on its own while you keep your hand free for Y.
5. spray 40., size 200.. It stops being a phrase and becomes a pad.
6. freeze 0, mix 0. The room comes back.

Step 6 is exact — mix 0 is bitwise passthrough — so the return is clean however far out step 5 went.

The one constraint

A grain born position behind the live edge and playing at rate r reaches position − size·(r−1) behind it by its end. Transpose up with the position near the live edge and the grain's tail runs off the front of the tape into the oldest material — a seam.

Nothing clamps it, because clamping would silently bend the pitch to keep the grain in bounds, which is a worse failure than the seam. Practically: keep the position at least size·(rate−1) back. At size 80 and one octave up that is 80 ms. Setting the X axis to start at 100 ms rather than 0 makes the whole problem disappear, and this is why the table above says 0–1500 rather than 0–1500 starting at zero.

What each ingredient buys, in order

1. A controller with two continuous axes. Without it this is a delay.
2. freeze. The half of the object you can build a performance on.
3. size. The texture, and the only control that changes what kind of thing you are playing.
4. A diffuseur after it. tap.palme~ @mix 40 sustains what the scrub chops; the strings fill the gaps that overlap 1 opens.
5. spray. Trades one artifact for another. Real, and last.

When to leave the recipe

• You want it in time. Nothing here syncs. That is tap.stammer~, on the same tape — literally the same capture code — and the two are meant to be swapped between rather than combined.
• You want a clean delay. tap.delay~ costs a fraction as much and windows nothing.
• You want the position to feel like a jog wheel. Put drift on a spring-loaded control and leave position alone: drift is velocity where position is location, and for wheel-like gestures velocity is the right variable.