LBH-118
18″ bass reflex/horn hybrid from Yavem for the low-cost the box 18-500/8-A – designer’s Hornresp data, 38 Hz (−3 dB) in a stack of four.
Primary source checked; some values are missing from the source or still open.
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Specifications
Link to section “Specifications”Every value with its provenance. If a value is missing from the source, it reads “not available”.
- Drivers
- 1 × the box Speaker 18-500/8-A Designer
- Enclosure type
- Hybrid
- Low-frequency extension
- 38 Hz (-3 dB) four enclosures on the floor, Simulation Simulated
- Sensitivity
- not available
- Max. SPL
- not available
- Power handling
- not available
- Impedance
- not available
- Dimensions (H × W × D)
- 600 × 630 × 850 mm Designer
- Volume
- not available
- Tuning frequency
- 40 Hz Simulated
- Weight
- not available
- Recommended high-pass
- not available
Dimensions from the designer’s text (60 × 63 × 85 cm, H × W × D). The drawing gives an overall length of 872 mm.
Description
Link to section “Description”In brief
A bass reflex/horn hybrid for an inexpensive 18-inch driver from the Hifi-Forum. All performance data are the designer’s simulations.
The LBH-118 is a bass reflex/horn hybrid for the the box Speaker 18-500/8-A, designed by Hifi-Forum user Yavem. In 2008 he presented the driver in the Hifi-Forum as an 18-incher “for very little money” and supplied two enclosures for it: a bandpass (JBP.118) and this hybrid.
What the designer states
Link to section “What the designer states”- a horn channel tunes the compression chamber of about 120 litres to a simulated 40 Hz
- 101 dB sensitivity (simulation, reference not stated)
- four enclosures on the floor: 38 Hz at −3 dB (simulation)
- horn length about 1.3 m at 60 × 63 × 85 cm (H × W × D)
- intended for 2 to 4 or more enclosures; according to the designer it benefits from stacking
The magnet system sits at the end of the horn channel, where it is better ventilated. If you want to cross over a single enclosure at about 110 Hz, the designer says you should cross over 10 to 15 Hz lower, because the efficiency rises again above that.
Theoretical model
The designer stresses that his plans are Hornresp simulations and that he gives no guarantee that they work in practice. We have no measurements of a built LBH-118.
Drawing
Link to section “Drawing”In the Lautsprecherforum.eu, the drawing “LBH.118 (18-500 8/A), 19mm Material, 63cm Tiefe” is collected together with a Hornresp graph. It refers to the 63 cm as the depth; in the designer’s text, 63 cm is the width. The overall length in the drawing is 872 mm, in the text 85 cm.
Why in “Low-budget subs”?
In the opening post the designer presents the the box 18-500/8-A as an 18-incher “for very little money” and targets requests for low-cost subwoofers for party music.
Original: für sehr wenig Geld
Evidence: Diskussion: The Box Speaker 18-500/8-A (Seite 1) (Post #1)
Drivers
Link to section “Drivers”- Original driver
Enclosure
Link to section “Enclosure”- Enclosure type
- Hybrid · How does it work?
- Shape
- Rectangular box
- Ports
- not stated
- Material
-
- Board material (not stated), 19 mm – specified: “19mm Material”
Build plan
Link to section “Build plan”We link to the original plan and do not host other people’s drawings.
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Open original document
Diskussion: The Box Speaker 18-500/8-A – Hifi-Forum (Beitrag #1)
Official source · accessed on 13 September 2026
Rights of use not stated – we only link
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Open original document
Pläne & Konstrukte für das 18-500 – Lautsprecherforum.eu (Sammlung mit Zeichnung)
Mirror copy · accessed on 13 September 2026
Rights of use not stated – we only link
Plan access: Free
Simulation
Link to section “Simulation”Simulations show the theoretical behaviour – they do not replace a measurement.
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Simulated · Designer
Hornresp
Designer’s simulation; the graph shows a stack of four in half space (2π). Input values are not published.
- Inputs
- Results
- Tuning of the compression chamber approx. 40 Hz, Sensitivity 101 dB (reference not stated), Four enclosures on the floor: 38 Hz (−3 dB)
Location in source: Post #1
Pros and cons
Link to section “Pros and cons”Pros
- Designed for a low-cost driver
- Benefits from stacking according to the designer
- Crossover advice from the designer
Cons
- Simulations only, no measurements
- Depth contradictory: 85 cm in the text, 872 mm in the drawing
- Usage rights not stated
Sources disagree: Depth
- 850 – Post #1, Text
- 872 – Drawing LBH.118
The text gives rounded centimetres, the drawing is dimensioned to a tenth of a millimetre. The source does not say which applies; recalculate the drawing’s dimensions before cutting.
Sources
Link to section “Sources”-
Tier B · secondary source
Diskussion: The Box Speaker 18-500/8-A (Seite 1)
Yavem · Hifi-Forum.de · 2 June 2008 (Date of the forum post) · accessed on 13 September 2026
Opened on 2 June 2008 by Yavem. The first post was later expanded into a collection (last edited on 18 March 2014) and contains Yavem’s description of the LBH-118 with simulation data. Page 1 was evaluated.
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Tier C · community
[Frei zum Nachbau] Thomann the box Speaker 18-500/8-A Pläne & Konstrukte
Jobsti · Lautsprecherforum.eu · 17 March 2014 (Date of the forum post) · accessed on 13 September 2026
Collective post with plans for the 18-500, including the drawing “LBH.118 (18-500 8/A), 19mm Material, 63cm Tiefe” and a Hornresp graph. Source of the drawing according to the post: HiFi-Forum.de.
Usage rights of the plan: Rights of use not stated – we only link. Added on 14 September 2026, last updated on 14 September 2026.