haaa Velodyne !
french distributor Hamysound is top notch,
but the subs ... mhhh
last year i 've been asked to conceive the sound for an art project showed at the Venice artbienal,
the sound were some boat/barge field recording processed,
as the visitors had to have the feeling that the boats passed thru the exhibition space, so the sound had to be very realistic, so we choosed to go really high end for the sound system
initially with 6 klinger favre Studio 15 above 90hz, and 6 DD18 bellow, with weiss sound card & converters to play the audio...
after one month of exhibition, i had to come back to the site because some huge detonations hapenned there, but when i say huge it was really to have an attac,
after a lot of investigation into the different points of the system, i isolated the problem coming from several DD18.
the distributor sent 2 brand new ones immediatly, as two speakers had been broken by the force of the detonation (they have been fully repaired after free of charge luckily).
after two days the same problem hapened !!! (but we took the dd18 out before they broke this time )
then i decided to change the whole subbass set up by Klinger Favre ones, Jean Jacques Bacquet (he's The Man ! ) helped me a lot on this lending free of charge 6 subs whom 2 where two enormous ones (110kg) that could reproduce down to 8hz !!!!!
i NEVER heard this !
i could not correct the frequency range with them, as their conception was minimalistic, but tuning their position i could end to have an even better effect than with the DD18
after having the 6 DD18 replaced i was still trying to figure what was hapening in there as neither velodyne or hamysound could figure what were producing those detonations.
i finaly ended up one month later to understand, and have been confirmed the truth by someone close to velodyne.
as you may know, in the digital drive serie the audio once filtered, pass to the amps, then to the speaker,
an accelerometer fixed onto the speaker measure its movement . this measurement is compared by the inboard cpu to what should be the theorical position according to the audio sent, then if the position of the speaker is not right the cpu order the amp to add extra power to replace the speaker in the right position.
it hapen that the CPU program had been realised to react to horizontal movement only.
The floor of the gallery was very old, and the bass produced was so huge that in some point it was vibrating verticaly, enough to have the dd18 moving with it (it's 65kg!)
so then the accelerometer was also measuring a vertical movement wich the cpu couldn't handle right,
so it was ordering the amps huge quantity of power to replace the speaker in what he calculated to be the right position,
the quantity of power was so huge that is was producing those enormous detonations. the speaker movement was so violent that the accelerometers start to get loosed from the speaker tehy 're supposed to be fixed on and so produced even worse reactions from the cpu ending in speaker breaking .
at that time no one at velodyne wanted to confirm this, it had been discretly told later by someone who confirmed me that they had the same concern with a russian petrol magnat who wanted one DD18 in each cabin of its boat (there where a tenth... no comment ... ) and they stated in the contract that the DD18 should not be in use when the boat where travelling or when the swell was too important.
so don't tell me about velodyne reliability ...
Klinger Favre ones have worked perfectly for the 5 month left to the exhibition, 9 hours a day.
conclusion:
better use a very well done traditionnal design than tricky high-tech things ...
at least it worked for me !
