bFly-Audio 4TUBE-2 – Absorbers for Tube Amplifiers

The bFly-Audio 4TUBE-2 is a set of equipment absorbers tuned to the uneven weight distribution of tube amplifiers, consisting of two softer and two harder absorbers.

A tube amplifier rarely sits evenly on its feet: the mains and output transformers make one side noticeably heavier. This is exactly what bFly-Audio developed the 4TUBE for – with MLA technology (Multi Layer Adjustment) and two differently tuned pairs of absorbers in one set. The MKII version adds an aluminium plug for more horizontal stability. You choose the height right here on the page.

Why the bFly-Audio 4TUBE-2?

The structure from top to bottom, as specified by the manufacturer:

• Cork with natural rubber
• solid aluminium body as a separating layer
• Cork with natural rubber
• Sorbothane
• Natural rubber as floor contact

Two absorbers with highly effective, softer damping belong under the lighter side of the unit, two with a harder tuning under the heavy side. The result, according to the manufacturer: the music sounds more relaxed, more spacious and therefore more natural.

What you hear

More calm in the background, a cleaner image – tubes in particular react sensitively to vibrations from outside. The absorber doesn't give you a new tonal colour, but ensures that the tube electronics can work undisturbed. Hand on heart – anyone who thinks decoupling is a matter of taste with tubes has rarely experienced how sensitively they react to shocks.

Who is the 4TUBE-2 suitable for – and who not?

Just right for tube preamps and power amps as well as tube integrated amplifiers up to about 50 kg with uneven weight distribution. Plain speaking: for solid-state units without tubes, the MASTER or the Pure is the more suitable choice. If you're looking for a particularly heavy tube amplifier or maximum effort, take a look at the Pure-Tube.

Our verdict

The 4TUBE-2 is the logical answer to a problem that most tube owners know without naming it: uneven load. Two pairs of absorbers, four height and thread options, one case – done. Which height suits your unit's feet, we're happy to work out with you at HD Zürisee in Wädenswil before you order.

Technical specifications

• Type: equipment absorber for tube amplifiers, MLA technology (Multi Layer Adjustment), MKII
• Structure: 5 layers – cork with natural rubber, aluminium body, cork with natural rubber, Sorbothane, natural rubber
• Set composition: 2 absorbers with softer damping (lighter side of the unit) + 2 absorbers with harder tuning (heavy side of the unit)
• Diameter: 44 mm
• Height: selectable 14, 21 or 28 mm – selectable right here on the page in the option «Height & Mounting» (no effect on sound, no price difference)
• Load capacity (manufacturer's figure): up to 50 kg
• Mounting: without thread (free-standing) or with thread M4, M6 or M8 (CHF 30 surcharge per set, only in 21 mm height)
• Colours: aluminium silver or black
• Manufacturer: bFly-Audio, Germany
• In the box: 4 absorbers in a case (2 soft, 2 hard), in the chosen colour, height or thread version

Frequently asked questions

Why does the 4TUBE-2 have two different pairs of absorbers?

Tube amplifiers are rarely evenly heavy: the transformers usually sit on one side. The set therefore contains two absorbers with softer damping for the lighter side of the unit and two with harder tuning for the heavy side. That way the unit stands in balance.

What weight is the 4TUBE-2 suitable for?

According to the manufacturer, the 4TUBE-2 is designed for units up to 50 kg. Weigh your unit and note how the weight is distributed. If you're unsure, we'll look together with you at whether the 4TUBE-2 or another bFly model fits better.

Which height should I choose: 14, 21 or 28 mm?

According to the manufacturer, the height has no effect on the sound. What matters is how much space is available under your unit and how high it should sit afterwards. Measure the height of your unit's feet; if in doubt, we're happy to advise you.

Can I screw the 4TUBE-2 in place?

Yes, in the option «Height & Mounting» you choose the version with thread M4, M6 or M8 (CHF 30 surcharge per set). The threaded version is only available in 21 mm height.

Why buy the bFly-Audio 4TUBE-2 at HD Zürisee?

Tube amplifiers are sensitive devices for which decoupling is especially worthwhile. We advise you on whether your model benefits and which height suits your feet. Call us, write to us or get in touch via WhatsApp, from our practice in Wädenswil.

Goes well with

For the tube amplifier, you'll find further solutions under Decoupling, and the stable base for it is provided by hi-fi furniture. The matching amplifiers are among the integrated amplifiers.