(Later addition: The linoleum triagle pyramid speaker may have a less flat frequency response than the linoleum cube Auratone 5C type speaker. More experiments needed.)
How it started:
It all started by inspiration from the Auratone 5C speakers used in the music industry for critical listening (no crossover network, no time distortion by point source radiation). Then the idea of using linoleum instead of wood came inspired by its use for membrane bass absorbers in broadcasting studios. Then Michalis drew a plan for horn mounting of Lowther speakers. Vicky inspired by this came up with the idea of making a triaglular pyramid since it embeds the horn shape.
Recent updates:
The Tesla fullrange 5in 4Ω drive unit had been hardwired to red black speaker cable. The linoleum color is red, the drive unit color is black, mounting Allen screws are black. So there is a 2 color code which look rather nice. An art object.
At the other end cable had been connected to iPad's mini headphone out. There was problem with the mini stereo jack and alligator clip cables used. Bad contacts etc. sound would fade in, out as cable were being moved around.
Tesla drive unit has been mounted with screws, washers, star washers nuts for the first time to the front panel of linoleum tetrahedron. Star washers are obviously at the juta side of linoleum. Drive unit had been fastened to place while tetrahedron linoleum net had been flat on table or held carefully by hands.
It was astonishing that after mounting the speaker and folding the linoleum by hands to create the triangular pyramid shape with its suitable 3 ears which will be thermal glued...
The pyramid could stand on its own, supporting firmly the very heavy drive unit and this was before the need to apply any thermal glue to the structure.
So some listening experiments could be carried out by opening the back of pyramid or closing it while listening.
Sound was quite good in both cases.
So far these are some advantages of the triangular pyramid by Vicky who came up with this ingenuous shape while discussing suitable shapes for speakers created from linoleum instead of wood:
Small standing wave coloration even when placing (attention to sound levels and hearing protection) ears close to open backed pyramid in order to listen to the sound field inside the object. This was done quite safely as the headphone output of iPad is of the order of same milliwatts.
Very rigid structure supporting very heavy drive unit while tetrahedron shape is self locked in place without using glue.
The front face even though made of soft linoleum does not seem to bend or change angle by the weight of the drive unit. Much much less that the linoleum Auratone type 5C Pleiades cube. This is partly due to the crossection of pyramid decreasing from base to crest.
Almost no coloration by listening close to the linoleum sides (attention to hearing from high SPLs needed) of the triagular pyramid. Only very nice quality bass can be heard possibly by sympathetic vibration of the larger area self damped linoleum surfaces. By comparison the cube sides emmit much much more mid range which is colored and somewhat ugly.
Obviously no parallel walls or enclosure sides.
By placing the tetrahedron linoleum speaker near a room corner corner. bass is increased by the Klipschorn effect, vibration of linoleum and walls crating the end of a relatively large horn. Bass projects to larger distance across the room.
Tests must be continued with class A (electrons flowing all the time) low power amplifiers.
And possibly constant music current drive with respect to frequency. For example on feedback class A amplifiers. Or a conventional amplifier in series with a seriws resistor for creating constant current drive. See Nelson Pass papers on driving fullrange speakers in order to avoid the transistor radio effect.
How does it sound so far?
Very natural.
Best sounding track so far is Billie Jean - Michael Jackson
This Girl's in Love - Warwick sounded great too.
It needs to conformed if frequency response is still flat within (+ or -) 3db as in the case of the linoleum cube with the Tesla drive unit.
Amazing transient response
No comments:
Post a Comment