— backs & sides that really sing

ARS and X-ARS are resonance-grade wood composites engineered specifically for guitar backs and sides by Turkowiak Guitars. In independent lab tests they showed higher Q (lower damping) than Indian rosewood and a clear lead over Mahogany (khaya), with excellent consistency across samples.

See results Download research report

Lower damping

High Q. Ranking: X-ARS ≳ ARS > rosewood ≫ mahogany.

Better projection

Higher ACE_R = (v/ρ)/tanδ. (Rosewood = 100) → X-ARS ~116, ARS ~115.

Consistency

Lower dispersion than solid wood. More predictable builds and tighter QC.

Resonance visualized

Conceptual view: composite backs & sides tend to store less loss and return more energy to the air/top.

Illustration of resonance potential — ARS backs/sides vs traditional solid (exaggerated, conceptual) — **Illustration (exaggerated):** ARS B&S show broader standing-wave activity; traditional solid B&S show more localized response.

What ARS / X-ARS are

ARS is a multi-ply, resonance-grade solid wood composite. X-ARS is the advanced variant with a ceramic-enhanced matrix. Both combine low internal losses with stiffness and dimensional stability — which in a real instrument translates into longer sustain and cleaner partials.

Why backs & sides matter

Backs and sides form the resonant cavity. Low losses (high Q) and easy radiation (high v/ρ) mean less energy wasted in the wood and more turned into sound. That’s why we show not only Q and Δf, but also ACE_R and LASS — indices that combine damping with stiffness-to-mass properties.

Results at a glance

Q factor: X-ARS 100, ARS 95, Indian rosewood 90, Mahogany 60 — higher is better — **Q factor — higher is better.** X-ARS ≈ 100, ARS ≈ 95, Indian rosewood ≈ 90, Mahogany ≈ 60.

Half-power bandwidth Δf at −3 dB: X-ARS 11.00 Hz, ARS 11.05 Hz, Indian rosewood 11.11 Hz, Mahogany 15.83 Hz — lower is better — **Δf (−3 dB) — lower is better.** X-ARS ≈ 11.00 Hz, ARS ≈ 11.05 Hz, Indian rosewood ≈ 11.11 Hz, Mahogany ≈ 15.83 Hz.

ACE_R normalized (Rosewood = 100): X-ARS ~116, ARS ~115, Mahogany ~85 — higher is better — **ACE_R (Rosewood = 100) — higher is better.** X-ARS ~116, ARS ~115, Mahogany ~85.

LASS normalized (Rosewood = 100): X-ARS ~197, ARS ~139, Mahogany ~68 — higher is better — **LASS (Rosewood = 100) — higher is better.** X-ARS ~197, ARS ~139, Mahogany ~68.

Key acoustic metrics (group means)
Material	Q (↑)	Δf [Hz] (↓)	ACE_R (Rosewood=100) (↑)	LASS (Rosewood=100) (↑)
X-ARS	≈ 100	≈ 11.00	~ 116	~ 197
ARS	≈ 95	≈ 11.05	~ 115	~ 139
Indian rosewood	≈ 90	≈ 11.11	100	100
Mahogany (khaya)	≈ 60	≈ 15.83	~ 85	~ 68

Durability & stability

Real-world use matters. Below are impact resistance, surface hardness, and humidity response — all critical for backs and sides that travel and age well.

Impact strength U (Dynstat): X-ARS 1.87, ARS 1.60, Indian rosewood 0.71, Mahogany 1.51 J/cm² — higher is better — **Dynamic impact resistance (U, J/cm²) — higher is better.** Both composites withstand impacts better than rosewood; X-ARS leads.

Brinell hardness HB: X-ARS 57.8, ARS 52.3, Indian rosewood 38.8, Mahogany 14.7 N/mm² — higher is better — **Surface hardness (HB, N/mm²) — higher is better.** Harder plates dissipate less energy at the surface and reflect internal sound more efficiently, which complements high Q. ARS and X-ARS exceed rosewood; far above mahogany.

Moisture after 72 h (~97% RH): X-ARS 8.8%, ARS 8.9%, Indian rosewood 9.4%, Mahogany 14.1% — lower is better — **Hygroscopicity (72 h at ~97% RH) — lower is better.** ARS/X-ARS take up less moisture than solid woods.

Swelling after 72 h (~97% RH): X-ARS 1.35%, ARS 1.44%, Indian rosewood 3.00%, Mahogany 4.00% — lower is better — **Dimensional stability (72 h at ~97% RH) — lower is better.** Composites swell much less than wood.

Durability & stability (group means)
Material	Impact U [J/cm²] (↑)	Brinell HB [N/mm²] (↑)	MC 72 h @~97% RH [%] (↓)	α 72 h @~97% RH [%] (↓)
X-ARS	1.87	57.8	8.8	1.35
ARS	1.60	52.3	8.9	1.44
Indian rosewood	0.71	38.8	9.4	3.00
Mahogany (khaya)	1.51	14.7	14.1	4.00

Why hardness matters for tone: higher surface hardness means less micro-indentation and lower viscoelastic losses at the boundary. The back and sides reflect internal sound more efficiently instead of absorbing it, which supports sustain and clarity. Hardness doesn’t replace stiffness (MOE) or damping (tan δ), but it works together with high Q to keep energy in the air and the top rather than lost in the shell.

What this means on the guitar

Expect longer sustain and cleaner partials than mahogany, with acoustic performance on par with — and often above — rosewood. ARS/X-ARS also offer tougher surfaces and calmer humidity behaviour, which helps instruments travel and age well.

Full research report

Study by the Poznań University of Life Sciences (Faculty of Forestry and Wood Technology), 15 Sep 2025.

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Both links point to the same study; the digital PDF is best for reading and quoting, the signed scan is for formal reference.