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“The texture is round and smooth, the details are clear but not loud”

Wen‧Dai Tiankai, U-Audio


The combination of the High Line “Bobby” S with two High Line “Bobby” Bass Extensions creates the High Line “Bobby” L, an absolutely performance oriented High End Set, with up to 400 watt power handling and incredible dynamic reserves.
In this particularly slim and full-size, full-passive bass reflex combination, 4 specifically interconnected 8 inch woofers provide a particularly clearly structured bass foundation with clear high-end ambitions, while the proven High Line “Bobby” S configuration in the center enchants the listener with its combination of midrange tweeter and horn tweeter.


Height: 1635mm

Width Front: 230mm

Width Rear: 280mm

Depth: 290mm







The SteinMusic Bobby M and Bobby L, means the Bobby S with Bass Extensions.

The Bobby Bass Extension is specially made to perfectly expand the capabilities of the Bobby S and Bobby S Signature monitor speakers to the size and performance of a floor-standing speaker.

The Bobby Bass Extension is a passive speaker with an integrated crossover, which is designed as a perfect match to the Bobby S speakers.
It has exactly the correct height to serve as a stand for the Bobby S.

There are two options to use the Bobby Bass Extensions:
Add one Bobby Bass Extension under the Bobby S, and you will get a Bobby M.
Add another Bobby Bass Extension on top of the Bobby S, and you will get a Bobby L.


The basic idea was to build a coherent and relaxed sounding speaker with an excellent impulse response.

An excellent frequency response, linear phase and perfect transient response for us are essential basics to create a good sounding speaker.
For the high frequencies we have chosen horns, because they allow a perfect adaptation of the membrane movement to the air.

Compared to a normal loudspeaker that has to move all the air in the room directly, we achieve a significant increase in the level of fine information.

We are not interested in increasing efficiency by using compression drivers.

For our taste this often leads to a somewhat thin and harsh sound.

Many years of development have been invested in perfect tuning between horns and drivers to achieve maximum sound finesse.

Technical Specifications

SPL: 89 dB

Impedanz: 8 Ohm

Crossover Frequencies: 80 Hz, electrically 18 dB; 2400 Hz, electrically 6/12 dB
Togheter with the mechanical filters this gives a very uniform phase and frequency range.

Frequency range: 34 Hz – 24800 Hz

Dimensions: height 1635mm, width front 230mm, width rear 280mm, depth 290mm


As bass speakers we use 2 pieces of the same 6” speaker with a carbon coated natural fiber cone, and extremely little mechanical losses as in the Bobby S.

By this we ensure to get a sonic characteristics which perfectly fits to the Bobby S.
The diaphragms of the bass is also treated with SteinMusic Maestro lacquer.
This treatment gives a very natural sonic signature, which is equal all over the entire frequency range that the Bobby M or L is able to reproduce.

We source those drivers from one of the best manufacturers, and besides the cone treatments we further modify and optimize them in many aspects to reduce mechanical losses and get an open sound with lots of detail and no colorations.

The bass speakers in detail:

  • Vented cast aluminum chassis for optimum strength and low compression
  • Proprietary cone material with natural fibers
  • Soft low damping rubber surround for transient response
  • Non-conducting fiber glass voice coil former for minimum damping
  • Extended copper sleeve on pole piece for low inductance and low distortion
  • CCAW voice coil for reduced moving mass
  • Long life silver lead wires
  • Vented pole piece for reduced compression

The tweeter in detail:

  • Copper cap for reduced voice coil inductance and minimum phase shift
  • Non-reflective rear chamber with optimized damping for improved dynamics
  • Flow optimized vented pole piece for optimum coupling to rear chamber
  • Fine weave soft fabric dome for smooth frequency response
  • Saturation controlled motor system for low distortion
  • CCAW voice coil for low moving mass
  • Long life silver lead wires
  • Low resonance frequency


The internal wiring is made of the finest solid core copper conductors.
The diameter for the bass is 1mm, for the tweeter we use exactly the same type of conductors, but have reduced the diameter to 0.5mm.The result is a better resolution of the higher frequencies and a coherent overall reproduction. 


Before designing a crossover, we carefully tuned and adjusted the drivers so that we can achieve the best results with a simple configuration that ensures that no details of the music in this area of the speaker are lost.


Each component of the crossover is of the best quality and was chosen after extensive listening tests. The most critical capacitor for the tweeter is an oil-impregnated film capacitor. We have opted for our favorite Mundorf capacitor in terms of sound. 

We receive these as raw windings and process them in our company according to our ideas and experience to a capacitor with a unique, fine, expressive sound without coloration. The coil in the bass range consists of individually insulated strands, and we use only our preferred Beyschlag film resistors as resistors. In addition to the classic components used in a crossover, we also use our proprietary InLine Matrix components to avoid magnetic distortions.

Cabinet Bobby S

The cabinet is a ventilated cabinet with short tubes in the front behind the high frequency horn.

It is wider at the back than at the front in a precisely defined ratio, which we have empirically found to be the best solution.

An important aspect of this construction is that there are no standing waves between the side walls.

Secondly, in combination with the 40mm thick rear panel, it gives the cabinets enormous stability against unwanted resonances.

This allows us to work without any internal damping material, which not only absorbs unwanted resonances, but also takes energy out of the music.

The Bobby S are equipped with solid walnut feet for a transparent but organic sound.

Cabinet Bobby Bass Extension

The housing is a vented box. The bass reflex tunnels are located close to the bottom, and we have chosen a contour that changes its diameter slowly over the length. Be this we get a much better contour of the bass.
The housing is wider in the back than in the front in an exactly defined ratio that we empirically found out to be the best solution here.
One important aspect of this construction is that we will not have standing waves between the sidewalls, which in addition are stiffened with a bar.
This gives the housings an enormous stability against unwanted housing resonances.

This allows us to work completely without any internal dampening material, which does not only absorb unwanted resonances but also always sucks out energy from the music.
Also the Bobby Bass Extension are equipped with solid walnut feet for a transparent but organic sound.


One pairs of speaker terminals at the Bobby S speakers allow the use in bi-wiring or bi-amping.
The choice of speaker terminals was a result of long listening tests of different models.
We finally decided for a sturdy version that allows the use of banana plugs or spades.

There are no further switches necessary, but depending on the positioning and characteristics of the listening room and personal preferences, you may use some of the acoustic foam parts in one or both bass reflex channels.


All drivers, crossover components, terminals and cables are processed with a special in house developed technology reduce material stress, and so increase the conductivity for complex signals.

In addition, we do use our unique quantum physical approach that you also find in our E-Pads. Bobby S and Bobby Bass Extensions are equipped with solid walnut feet for a transparent but organic sound. In addition the Bobby Bass Extensions have receptions for these feet from the Bobby S in their top, and the contact surface is massive mahogany.