Simon Lewis

OK... that makes more sense.....

So Thomann have made it easy for the non commercial purchaser. However, it seems that the VAT registered business purchaser now has to claim back VAT incurred in the EU from the EU! Link (there's a few dead links in that government webpage). It can take "up to six months"...

This looks good... however - how does this work for VAT registered entities? Is there still the requirement to make a full, simplified or delayed declaration (with the various softwares or schemes that need joining) or does Thomann notify HMRC on your behalf?

That is where ISCVE stepped in.... They already have a fairly robust process for determining member grades, recognising both formal and experiential learning, so they are able to issue (after joining ISCVE, completing H&S assessments and paying card fees) an ECS card for AV and sound engineering disciplines. They ascertain and vouch for the candidate's learning and experience level.

I think there's little doubt that the H&S assessment is pretty basic, and often simply requires the selection of one obvious answer from a pack of four. However, as mentioned earlier, the CSCS scheme (and I believe ECS) has and continues to move away from the situation of virtually meaningless cards handed out with little fuss (e.g. this article). I'm not really trying to champion these schemes and it can be annoying when you are trying to access a building site and have to produce credentials, but I believe the intent is good and that (hopefully) standards will improve.

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In theory, having some form of proof of skills might not be too bad a thing.... The broader scheme, Construction Skills Certification Scheme is meant to show that you are trained / qualified for the level of work being done on a construction site. The Electrotechnical Certificate Scheme takes care of the electrical trades, and is the nearest that we are likely to get for our AV type work, where we need to work on new builds - hence the ISCVE's welcome involvement in this area. It may well be viewed as a money making setup, useless etc. but I'd argue there's at least some merit in this, in allowing skills to be verified. It's pretty standard for fork lift and telehandler ops to need to prove they are trained before just driving off 5 tons of machine on a festival site. Obviously, it's possible to blag or sidestep these things, and the level of knowledge required for some assessments is quite low, and they tend to stick to fixed formulaic assessments, but hey - perhaps a step in the the right direction? That said, I'm not the greatest fan of the way in which most of these card schemes are delivered...

There was a a change several years back, where the old cards (almost free with cornflakes) were changed for ones which required demonstration of training or qualification in the specified skills area. Sparkies needed the relevant C&Gs etc. This presented something of a problem for many sound engineers who might not be able to point to recognised awards. The Institute of Sound, Communication and Video Engineers negotiated a scheme where those in membership with the ISCVE and who have taken the ECS Electrical Safety Unit assessment and the ECS Health, Safety and Environmental Assessment can apply to ISCVE for an ECS card (Sound Engineer or AV Engineer). It does cost a bit, but the value is that ISCVE through their evaluation of prior accredited or experiential learning (in granting the appropriate membership grade) effectively validate the qualification aspect that's needed for ECS. There's details here. ISCVE are a good bunch... I'm a member and enjoy their small but effective trade show etc.

Slight correction... the other side is just induced noise.... not inverted noise. The whole point of twisted pair is to ensure that the same noise signal is picked up on both cores. The differential input then cancels any common mode (noise) signals. Unfortunately, a belief that some combination of inverted and non inverted signal is doing the noise cancellation has arisen, This also explains why a balanced signal doesn't have to be symmetrical or even on two wires. The identical impedance to ground helps ensure that the same noise signal is induced.

plus - this is far from unusual... many schools have just one person who understands the sound and lighting gear, and when they leave all knowledge goes with them, despite any attempts to record it or pass it on. That's not to say poor techniques or workmanship should be ignored or condoned, but just to highlight this story is repeated across hundreds of schools.

That rather sounds like a Distributed Mode Loudspeaker.... One of their attributes is the ability to excite pretty much any suitable surface, so the device could be made as a picture, plastered into a wall or made into a whiteboard. However, the dispersion characteristics are completely different from the Holosonics panel (where the directivity pretty much is down to the dispersion of the ultrasonic transducers - i.e. narrow). Instead, the DML is dispersive, generating a plane wave with diffuse radiation. It is also bipolar with summative rear radiation, exhibits linear loss of sound intensity with distance (for as long as the panel is acoustically "large") and can reproduce over ~ 8 octaves without a crossover. Interestingly, rather than being subject to the pistonic behaviour of traditional loudspeakers, the DML has the opposite behaviour of increasing dispersion with increasing frequency. This makes it really good for such applications as ceiling speakers (usually as a drop in ceiling tile) as it reverses the annoying tendency of traditional speakers to only sound full range immediately beneath them, and to lose HF as the listener walks away and goes off axis (thus losing speech intelligibility). DMLs can project some distance, but I wouldn't say that they are highly directional, so not much use to our OP. There was another highly directional panel in addition to the ultrasonic array approach, which I think was based on some form of capacitive drive, perhaps in a Bessel array? I'll try and find it...

There's a few approaches to this, either using an array or panel to achieve directivity or using ultrasonic transducers to blast out high level ultrasound that gets demodulated "in mid air". Both can effective, but users of the old style analogue hearing aids found that the ultrasonic device would swamp the aid's front end and produce painfully loud artefacts in the audible band. Fortunately, digital aids tend not to suffer the same fate. Spotphonics and Holosonics (Bryson's link) are two names that come to mind. However, the dome type covers work with standard technology and don't deafen animals...

I have used the USB version of D-Fi with Chauvet Slim Par Pros which have the corresponding USB socket. Transmitter was the small D-Fi hub. Generally, they work very well indeed. I had an application where a bunch of fixtures were used in a listed building, and running DMX to each one was problematic from an access and cable management perspective. The wireless DMX controlled the fixtures well, and saved lots of hassle. However... There was an occasional glitch which would either cause one fixture to turn off for a second or so, or sometimes to flash. If the wireless system had been used on a gig or DJ set with the usual lighting changes, it may be that this would hardly ever be spotted, but our application was effectively house and architectural lighting, so the drop outs were pretty noticeable. We tried scanning the wifi environment (- a city centre, so a little busy but not overly so) and we changed channels and altered the venue's wifi transmitter channel. We tried different desks, relocating the D-Fi hub, and even tried it on channels 15&16 (ssh!!). Even with some very good support from the manufacturer, we weren't able to eradicate the issue, so in the end we went with wired DMX. I cannot say whether the D-Fi units you are looking at would ever show this problem, but can state that there's been no problems at all on the described system with wired control.... I guess this is pretty obvious stuff, but that's the risk you get with wireless DMX.

A colleague worked on a research MRI scanner, with several Crown DC300s driving an improbably low resistance....

I started my little hire operation around the same time as Mark, and was probably doing bigger events, but whereas I wasn't that ambitious (or successful !) and eventually followed other opportunities, he kept growing and improving!

The d&b release is far more explicit.... d&b have acquired SFL. Indeed... I wonder what effect the l'acoustic's / DeltaLive takeover had, and whether it influenced this decision. I wonder too what the Solotech companies in the UK will make of it....

An interesting move... SFL join d&b.... https://www.sfl.live...-the-db-family/ https://www.dbaudio.com/global/en/about-db/press/newsroom/db-launches-new-solutions-business-acquiring-full-service-uk-integration-firm-sfl-group/

And on top, you find that every ring circuit has had several outlets with built in USB chargers fitted ;-)

On Site Guide says to either temporarily disconnect them or join L & N together and test between that and the CPC. It's probably wise to use a lower voltage too...

...but do impress on any electricians that standard circuit insulation resistance tests may well cause damage to a dimmer hardwired to the IWB. They ought to know this, but.... ;-)

I was thinking more in terms of the time and management overheads needed in establishing, promoting, measuring and monitoring sustainable practice. The practical steps you mention are great - and may well be easily implemented in cost effective or cost saving manner. My (admittedly limited) experience of implementing sustainability at a business wide level so that it's part of the company's mindset and practice, is that this does have a cost attached. Sustainability Management (e.g. achieving compliance with ISO 20121) may well (eventually) save money, safeguard revenues, or even help generate additional income, but I felt this might not be the first thing that companies would focus on right now?

Looks interesting.... I fear that some aspects of sustainability may be put on the back burner in deference to survivability right now though...

Good to hear from you!! Like many old Avo desks, I'm officially retired, but still get out to play with stuff from time to time ;-) Feel free to DM me!

The use of mass to reduce noise transmission has been mentioned several times in this thread. It's true that increasing mass will help - in fact the mass law states that every doubling of the mass of a partition will result in a 6 dB reduction in the level of sound transmitted through it. Similarly, rigidity (stiffness) can reduce transmission - particularly for low frequency control. However.... The mass law applies strictly to limp, non-rigid partitions. Most materials used in buildings possess some rigidity or stiffness and this means that other factors must really be considered, and that the mass law should only be taken as an approximate guide to the amount of attenuation obtainable. Sound attenuation in ordinary building materials is the result of an interplay between mass, stiffness and damping. In addition, the mass law is affected by resonance at lower frequencies and coincidence at higher frequencies. Therefore mass and rigidity on their own may not lead to an effective (or affordable) noise control solution...

Thanks all for discussing this topic (and for some lovely diversions!). The issues wrt consumer purchases (Customs Duties over £390, VAT collected by seller under £135 and by delivery firm plus fee and any VAT due over £135) seems relatively straightforward. I'm still looking through the guidance on purchasing stuff as a VAT registered business. However, given the issues with couriers at the moment, I'm holding back from placing any orders until things have settled down and the procedure is clear and working...