Profile Acoustic Research has developed a patented-pending family of loudspeaker transmission line architectures that deliver deeper bass extension, reduced thermal compression, and lower distortion — entirely passively, in your existing cabinet.
TL1BASELINE
Single backwave transmission line. Converts rear cone energy into reinforcing low-frequency output. Eliminates port noise and resonance.
TL1
eTL1™EXTENDED
Adds a second acoustic pathway dedicated to passive voice coil thermal management. Reduces thermal compression and increases sustained power handling under continuous drive.
TL1TL2
eTL1+™RETROFIT+
All three acoustic pathways active inside the sealed cabinet. Maximum retrofit performance without external channels or cabinet modification.
TL1TL2TL3
DTL™DOUBLE
Dual-path optimization of backwave and voice coil thermal channels with independent resistive fill profiles for each path.
TL1TL2
TTL™TRIPLE
Full three-path architecture. Adds spider/suspension IMD dissipation at the source. Dominant advantage at 15″ and above.
TL1TL2TL3
~38%
F3 reduction — deeper bass, TTL™ vs conventional
~52%
Thermal compression reduction — TTL™
~49%
THD reduction — TTL™
5
Architecture tiers — retrofit through new design
How it works
Three independent paths. One passive system.
Each PAR architecture activates one or more acoustic pathways simultaneously. No active components, no external power — all performance gains come from enclosure and driver-level engineering.
PATH 01 — TL1
Backwave Transmission Line
Channels rear cone radiation through a resistively-loaded line, converting it to phase-coherent bass reinforcement at the terminus. Eliminates port turbulence entirely. Present in all PAR architecture tiers.
Deeper bass extension — no larger cabinet
No port noise or chuffing at high SPL
Lower effective noise floor
PATH 02 — TL2
Voice Coil Thermal Path
Establishes continuous passive airflow across the voice coil gap and pole piece, driven by cone excursion. Reduces VC temperature rise and thermal compression. Active in eTL1™, eTL1+™, DTL™, and TTL™.
Reduced thermal compression
Higher sustained power handling
Extended driver service life
PATH 03 — TL3 Active in eTL1+™ & TTL™
Spider / Suspension Path
Dissipates mechanical energy at the suspension assembly, reducing intermodulation distortion at the driver level before it enters the acoustic chain. Scales with driver diameter. Active in TTL™ only.
IMD reduction at the source
Dominant effect at 15″ and above
Lower mechanical noise floor
Verified production design — currently available
One design. Five architectures. Measurable results.
All driver and cabinet parameters below are from actual build specifications — not estimates. Performance improvements shown for each PAR architecture tier are calculated from these verified numbers.
12″Driver diameter
22.0 HzFs free-air
0.43Qts free-air
2.84 ft³Vas
12.5 mmXmax
250W RMSPower handling
507.3 cm²Sd
1.2 ft³Production cabinet
Architecture comparison
Performance by tier — same driver throughout
TL1 and eTL1™ are retrofit-compatible — same 1.2 ft³ cabinet, better performance. DTL™ and TTL™ are new-design architectures — smaller cabinet, substantially better performance across every metric.
Active acoustic pathways
Paths active — all architectures (maximum: TTL™)
Performance metrics
Before and after — verified numbers
Baseline is the same driver in the same 1.2 ft³ cabinet with no PAR architecture applied.
Eight problems · Eight solutions
What PAR resolves — and how
Select an architecture tab above to see which problems it resolves and how the solution changes across tiers.
One partnership · All eight solutions
Every limitation resolved. Every benefit passive.
The PAR architecture family is available for licensing — from TL1 retrofit through TTL™ new design. Full technical documentation, build specifications, and engineering support included.
Contact PAR
licensing@profileacousticresearch.com
Crown Point, Indiana · Patent Pending
Performance Modeling Tool
Enter your driver specs. See the PAR advantage.
Input your Thiele-Small parameters and current enclosure alignment. The calculator models each PAR architecture against your design and quantifies the projected performance improvement — F3 extension, thermal compression reduction, THD reduction, and power handling gain.
Driver size — select then enter your parameters
Custom size:inchesEnter any driver size not shown above
Thiele-Small parameters
Current enclosure alignment
Issue
TL1
eTL1™
DTL™
TTL™
Fully resolvedPartially resolvedNot addressed
Advanced Modeling Suite available under NDA. Full frequency response curves, group delay plots, excursion modeling at rated and peak power, cabinet geometry optimization, and a complete exportable engineering report.
Profile Acoustic Research LLC is an Indiana-based acoustic engineering and intellectual property firm founded on a single premise: every performance limitation in a conventional loudspeaker enclosure has a specific physical cause — and a passive engineering solution. The PAR architecture family is the result of that work.
5
Architecture tiers — TL1 through TTL™
3
Independent acoustic pathways per system
0
Active components — entirely passive
The Problem PAR Solves
Conventional loudspeaker enclosures — ported, sealed, bandpass — all share a common set of fundamental limitations. Rear cone energy is either wasted or imperfectly managed. Voice coil heat accumulates, compressing sensitivity and reducing dynamic range. Suspension nonlinearities generate intermodulation distortion that no downstream DSP can fully correct without a cost in transient accuracy.
These are not amplifier problems or DSP problems. They are enclosure and driver-level problems — and they require enclosure and driver-level solutions.
PAR's Transmission Line architecture family addresses each of these mechanisms independently and simultaneously, through three acoustic pathways engineered into the enclosure geometry and driver assembly itself.
The Architecture Family
TL1
TL1 — Baseline
Single backwave transmission line. Foundation of all PAR architectures. Eliminates port turbulence and extends F3 without increasing cabinet volume.
eTL1™
eTL1™ — Extended
Adds a second acoustic pathway dedicated to passive voice coil thermal management. Reduces thermal compression and increases sustained power handling under continuous drive.
eTL1+™
eTL1+™ — Retrofit Triple
All three PAR paths active inside the sealed cabinet. All three acoustic paths contained within the sealed cabinet. The TL2 thermal path is open to the cabinet interior — negligible volume displacement. TL3 operates at the driver assembly. Maximum retrofit performance: near-TTL™ improvement without external channels or cabinet redesign. From scratch: 0.85 ft³ (29% smaller).
eTL1+™
eTL1+™ — Retrofit Triple
All three PAR acoustic pathways active inside the sealed cabinet. The TL2 thermal pathway is open to the cabinet interior — negligible volume displacement. TL3 operates at the driver assembly — no cabinet volume consumed. Near-TTL™ performance as a direct retrofit. From scratch: 0.85 ft³ (29% smaller).
DTL™
DTL™ — Double
Simultaneous dual-path optimization of backwave and thermal channels with independent resistive fill profiles. Significant gains in sustained SPL and LF extension.
TTL™
TTL™ — Triple
Full three-path architecture. Activates TL3 spider/suspension mechanical path. IMD reduction at the source. Dominant advantage at 15″ driver diameter and above.
IP and Licensing
PAR's architecture family is currently pursuing patent protection. The intellectual property covers the enclosure geometry, driver integration methodology, resistive fill material specifications, and the interaction between all three acoustic pathways.
PAR licenses its architecture to loudspeaker manufacturers through a structured program combining an annual flat fee and per-unit royalties beginning in Year 2. Licensing is available at the individual architecture tier level — a manufacturer may license TL1 only, or the full TTL™ suite, depending on their product requirements.
All licensing discussions are conducted under mutual NDA. Technical documentation, performance modeling data, and build specifications are provided to prospective licensees as part of the evaluation process.
Founded in Crown Point, Indiana
Profile Acoustic Research LLC is headquartered in Crown Point, Indiana. PAR was founded by Gregory Keller, an inventor and engineer whose work on transmission line acoustics began with the observation that no manufacturer had addressed the backwave energy problem, the thermal compression problem, and the suspension IMD problem as a unified system — despite these being the three most consistent limiters of loudspeaker performance across all conventional enclosure types.
The PAR architecture family is that unified solution.
Get in touch
Let's start a technical conversation.
Whether you're evaluating PAR for licensing, requesting access to the Advanced Modeling Suite, or simply want to understand the technology in more depth — we welcome the inquiry.
All licensing discussions are conducted under mutual NDA. The PAR Advanced Modeling Suite — including full frequency response curves, group delay plots, excursion modeling, and exportable engineering reports — is provided to prospective licensees as part of the formal technical evaluation process.
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