what protection lamps do i need?
in [Live Sound]
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From: Eeyore on 14 Jun 2007 06:35 Phil Allison wrote: > "Eeysore" > > > >> cabinet fire, > > > > That'll only happen if it's poorly installed. > > ** Not even possible. > > 1. The glass surface temp of a hot lamp will only slightly darken the > surface of any plywood or particle board it is directly in contact with. > > 2. Where white polyester or acetate lining material is used and contacts the > same hot glass, the material shrinks and darkens only. > > 3. Where yellow fibreglass type material is used - nothing happens. > > It is only with WRONGLY designed lamp installations that the lamps glow > brightly other than on those normally rare occasions of sustained acoustic > feedback. > > On the many such installations I have engineered over the past 25 years, > even with disco music programme played at DEAFENING levels, there is no > visible lamp glow. I actually have a stage monitor to open up later today. It's one I recently refurbed so I'm interested to see what's up. There are typically 2 of these driven by an amp delivering 600W into 4 ohms. I have come across plenty of blown protection lamps btw. I've no idea how hot they can get in that condition. The former idiot 'landlord / manager' thought because he played bass, he knew something about audio. When the lamps blew he *linked them out* and then blew the HF drivers. When the HF drivers blew he either threw the monitors in the shed or fitted piezos in place (which then also blew of course) and threw the HF drivers and flares AWAY or bought some really crappy second hand monitors to replace them, whereupon the 'new second-hand monitors' rapidly lost their HF units too ! I kinda 'gave up' on the venue when it went through this phase. The lamps in those monitors were well-known for a lot more than *glowing* btw. Even the protection lamps in the EV 'top boxes' (QRx 212/75) have blown too. EV charge an outrageous sum for them but without knowing what the spec is there's little you can do other than cough up. Graham
From: Eeyore on 14 Jun 2007 11:43 liquidator wrote: > Graham is a total twit. I probably have done a hundred gigs for every > one he's done- and blown less drivers. The above was about the local venue who have various ppl doing the sound engineeringand the gear gets hammered sometimes. It needs to be 'gorilla proof' and DJ proof. too actually. I've very rarely blown drivers. In fact I can only think of one occasion where two went. They weren't protected. Rather fragile RCF units. Graham
From: Eeyore on 14 Jun 2007 11:45 liquidator wrote: > If the OP really wants lamps, just buy Eminence crossovers- they > already have lamps and are cheap. Very small lamps designed to protect their APT series tweeters, not an 80W JBL driver. Don't lecture about hardware- you haven't a clue about it. Graham
From: Eeyore on 14 Jun 2007 16:10 Phildo wrote: > <non-biz(a)hotmail.com> wrote in message > > > > I know- thats why im trying to ask who i think are experts but your > > proving me wrong with your upity responses. > > Sadly you have encountered two of the biggest cretins on the group - Mr > Assillon and Graham (Eeyore). Assillon is mentally ill, Graham used to be a > respected poster (and created or stole designs for studiomaster) but has had > a nervous breakdown recently and is now regarded as little more than a > figure of fun. You are best off ignoring both these posters along with one > Arny Kruger and Mike Dobony. Pretty much everyone else is worth listening > to. Phildo is the local clown / village idiot. He's never been the same after a near-death experience from over-eating. Graham
From: Ian on 14 Jun 2007 16:21
On Thu, 14 Jun 2007 10:35:28 GMT, Eeyore <rabbitsfriendsandrelations(a)hotmail.com> wrote: >I have come across plenty of blown protection lamps btw. I've no idea how hot >they can get in that condition. > >Graham Hot, but not hot enough to set fire to anything inside a speaker cabinet. I've had quite a few lamps fail, but in all but a couple of cases the lamps have failed for simple mechanical reasons, such as broken filaments or old age. A simple autopsy of the lamp and examination of the filament will indicate the type of failure. http://www.tcforensic.com.au/docs/article10.html The link above has the phycial ignition points etc for a variety of materials. From my own measurements lamps with a non contact hand held thermometer show envelope (globe) temperares in the 15-100W regular incadescent (GE/Sylvania etc) bulbs from 80�C to 280�C Those figures are based on an ambient temperature of 25�C. Cheers, Ian |