Stones Sound Studio Ribbon 260, Руководство пользователя, Страница: 7 / 32

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Loudspeaker Description
• Enclosure Rear Port
A rear port was employed in the ribbon speaker design to ensure a reduction of overall transducer distortion and
cross modulation generated by front ports.
With a front port a form of speaker (low frequency) distortion and cross modulation is generated by the chamber
compressed air exiting the port out of phase with the woofer creating (modulation) interference of the woofer cone
and ribbon diaphgram .This interference of the woofer cone occurs at medium to high playback levels (port
velocity) and is one of the factors reducing over all dynamic range or head room of the transducers and
speaker system.
This mechanical process is similar in principal to FM & AM radio wave modulation only in this case, the radio
carrier wave is the transducer cone or ribbon diaphgram and the modulator is the low frequency compressed air
radiated from the port.
Port Flare
A simple 63 mm (ID) port size with small flared ends was chosen over large flared ports to provide minimum port
velocity, cone excursion and minimum woofer power compression at average to high volume levels.
At average to high volume levels, large radius ports cause eddy current airflow resistance at the inlet, exit flare,
and thus more power compression, less dynamic range and increased driver distortion.
Enclosure Bracing and Felt Acoustic Damping:
An MDF timber acoustic bracing rib was designed with a bullet round over on the edges to reduced unwanted
chamber resonance, standing waves (pressure particle bunching) caused by the back waves of the bass/ mid
woofer and to reduce unwanted side panel resonant modes
Grey Felt 6mm thick acoustic material is fitted to the top,bottom,left,right and rear panels and carefully folded
over the bracing rib to act as an absorber ( air brake) on lower midrange frequencies that cause modulation of
the cone and port vent . Two layers of 6mm felt are added to the inside of the rear panel and further damping is
added the rear of the ribbon tweeter to reduce air turbulence of the rear port and interference from the back of
tweeter magnet assembly
Grill Panel
The grill panel is located on the front baffle by grill pegs and cups and incorporates the use of low loss acoustic
grill cloth. The grill frame features round over of the timber grill frame internal and external edges which reduce
diffraction of the sound generated by the speaker drivers .A special low loss grill cloth has been used to reduce
attenuation of high frequencies from the ribbon tweeter and woofer. “
To enable the very best sound quality and
listening experience I recommend the grill panel be removed from the speaker box “
Enclosure Features Summary:
•
Low resonance baffle design with 36mm thick laminated 18mm MDF
•
High volume level High Velocity low compression port with round over at both ends
• MDF acoustic bracing rib with bullet shaped round over on edges
•
Acoustic felt damping on all walls and rear panel
• Acoustic Felt cover behind ribbon tweeter
•
Acoustic grill panel cloth Low loss
•
Grill panel frame internal & external frame round over’s
•
woofer hot cut outs 16mm roundovers on inside edge