leather carpet speaker 1 short

The fifth prototype of "syrinx," the "leather-wrapped carpet speaker," is now complete.

[Specifications]

• Speaker unit ALPAIRE7 v3 (ported from prototype 1)
• Tube length 300mm
• Cylinder diameter φ=138mm
• Enclosure: Genuine cowhide leather t=4.0mm
• Base Stainless steel vibration t=3.0mm

[Speaker unit]

The ALPAIR7 does not produce bass at first, but as it ages, it will become more powerful. This time, I replaced it with a unit that had been aged for about six months. If you feel that the bass is lacking, placing it in the corner of the room will improve it considerably.

[Tube length]

The height is 30cm to prevent it from falling over. This is to protect it from children.
Even at this length, the bass is still sufficient thanks to the stainless steel base at the bottom and the aged ALPAIR7.

[Tube diameter]

This time, we did not use a baffle plate, but simply wrapped thick leather around the 13cm diameter unit. This is to eliminate the incidental noise caused by the baffle plate and make it closer to a point sound source.

【enclosure】

It is made of 4mm genuine cowhide. In order to secure the speaker unit, we used thick, non-stretchy leather. The leather is dyed all the way through to the inside, so the cut surface is beautiful.

With regard to the material for the soft enclosure, experience has shown that the following three points are important:

• Sound absorption...Weakens air column resonance, attenuating mid- and high-range sounds while retaining low-range sounds.
• Sound insulation: Light and thin materials tend to leak sound from the sides. Airtight materials with large internal loss are better.
• Resonance: Even slight reverberation has a large effect on the enclosure. Softer materials are less likely to resonate. Harder materials are more likely to resonate and cause air column resonance.

However, soft materials that absorb sound well are prone to sound leakage, while materials that are airtight and have good sound insulation properties are hard and prone to air column resonance and vibration.

In this respect, carpets are an ideal material that fulfills all of the following requirements: sound absorption, sound insulation, and resonance. The carpets have a large pile, which results in a large internal loss. They also have sound insulation properties, and increasing the number of turns makes the sound more solid.

The genuine leather used in this project is a material with high internal loss, with fibers entangled in every direction. It is also airtight and has a moderate weight. It does not absorb much sound, so it is not suitable as an enclosure by itself, but if combined with a material with high sound absorption properties, it could become an ideal soft enclosure.

【base】

The base is made of a 3mm thick stainless steel vibration disk. The space under the base is important for reducing mid- and high-pitched sounds and balancing the bass. This time, the gap is about 6mm.
If you leave no gaps and use a sealed design, the sound will be a bit muffled. Allowing air to escape from underneath will produce a smooth, clear sound that is characteristic of carpet speakers.
However, if the gap is large, mid- and high-range sounds will easily leak out, so it is better to make it relatively narrow.
The size of the disk also affects the bass.

【sound】

We had a hard time choosing the right sound-absorbing material to combine with the leather. A normal carpet would not suffice, and in the end we found that a soft shaggy rug made of microfiber worked best, producing a clear sound that made us forget how short the room was, at just 30cm.
This time, we focused on not only the sound, but also the rational structure, texture of the materials, and design.