sunray

Judging by the unfinished state of the building any trade could have left something undone.

If it is a length of unistrut, I've regularly seen M6 or M8 studding drop rods with only square washer and plain nut holding a unitrut to support ducting. the theory being when the weight of the duct is installed then the nuts are adjusted for level and a locknut added. The second stage all too often seems to be forgotten. Of course if it is Unistrut that has fallen it could easily be a piece missed (or incorrectly installed) by any of the other contractors; Ceilings, Electricians, Plumbers, Sprinklers etc in no order other than alphabetical.

Personally I'd rather have food.

Hopefully a picture speaks a thousand words. Half wave rectificationwith 2 diodes in series with one reversed. No current can flow in either polarity: Solution: reverse the load: I recall this problem cropped up a lot of years back on some model railway points motors where different manufacturers opted for the opposite polirity and therefore incompatible.

Going back 25 years I was in this position, a mobile disco CO-OP brought in 4 with blown bulbs, they were 1*15" 400W, 2*12" 250W, 4* tweeter (3" ?) all Celestion & 4*piezo. Marron carpet & grill covered. The tweeters and piezo were protected by 2 festoon bulbs (2 tweeters and 2 piezo per bulb IIRC). Luckily they had more similar speakers, I wired one of their good bulbs in series with all ratings of festoons available from an automotive outlet and did a simple comparison on a variable supply measuring the voltage across each bulb. 12V 18W was the closest match. I used to keep a stock of 24V 45W bulbs for Bose 802's (then 12V 12W when the 45's became unavailable) where so many used to come in but they are a very different beast.

Indeed. In 1969 I used a valve amplifier (ECC81 & PL84) and loudspeaker robbed from a record player, LT & HT PSU's from physics dept, headset from language lab for comms between MD (Known as organist) and lighting. I soon added c/o switch to isolate LS and enable Foster DF1 microphone to talkback to MD. used for 2 plays a year apart. After leaving school I joined a little theatre club and installed the same system into there for use between SM/sound position to lighting but knocked up a basic PSU, changed the PL84 to EL84 and the C/O switch to PTT button and used the LS as the talkback mic. I did 2 plays there as lighting op and left it in place. About 10 years later I went to a show and it was still in place and lit so I assume being used.

I've done this several times with a half coupler or hook clamp and 1/4"W bolt, 2 penny washers, nut and wing nut As mentiined adding a ball joint will make things much easier

If it's a 6th form college there are likely to be technical students with contruction abilities. Look on this forum for blueclone.

This sort of sleeving makes a good multicore https://www.ebay.co.uk/itm/175821632523?var=475224440614&itmmeta=01HVMD1FW5CW4TMA1EKRXBBY9V&hash=item28efc9340b:g:8XEAAOSwaxBktPWf&itmprp=enc%3AAQAJAAAA4O83tJaNvCmVhFZdXqXoVTLD5OAq6aCfYLqo1hbc2tgFXN%2FqVQVFdJvosaVxeYzcCeR8uwqiFGe8%2BF2oFUkwAJSjSGpzjqV8hAFzBOeI6z2EFntnMKxr43Lf5xEoInaS4PxXBY8IVA1H%2BLO3eqmfty9ZPtTzmDWJaLNJHLjDIcx19cX2j68Y1hq%2F0ITC5HZSodc3PO%2FVzvyu%2BeepxQZ4ppDgGZjqrKDPzU94ffRdx9BOpY1Vii1Tq8wZH7aHNSucMhy0nP1R09HFbZPpPFJRYKh8hMQ3BXQA5SjXZyZTXjCD|tkp%3ABFBMsv6Fjd1j I often position radiomic receivers nearer to the source rather than run long aerial cables. Bear in mind you will require a working space of at the very least the length of any loom you make, I've found it's easier to draw the sleeving onto the bunch of cables rather than pull them into the sleeve in which case you require twice the length. The longest I've done has been 50m, that requires at least 3 people but the end result is worth it.

I have no problems with the operation if they are individual & isolated, however to date I've only encountered them in groups of 4, 6 etc and so far only a common pin, I made up a cable just a couple of weeks back, DB25 (with only one common) to 4x 8 pin Din (with one common each) which is typical of what I've come across and until now assumed it's standard..

How does that work?

I've had involvement with wireless DMX twice, one was the issue of sequencing the start-up routine to revent them going into transmit and we had to replug mains services to achieve that however after that we found the system, and the other had the same issue, developed delay issues when the venue filled up, at a scene change there were some, but not always, obvious delays between the cabled fittings and those on wireless links and also odd flickers. One of them had 3 significant glitches coinciding with the goals scored in a football match which was the clincher for us.

I find with many things like this it's not worth making your own... But of course that's how I've always done it. A little while ago I installed 16XLR audio tiepairs between stage and control desk in a school hall. It was just cheaper to buy a ready made snake from CPC than to buy just the 16 way cable.

it was common to use 4 cat 5's in an overall sheath to simplify structured cabled ethernet but sadly not flexible. I used to use 7 pair stranded cat 5 a fair bit, we used to get it on 500m drums and behaved itself for portable work, even the overall braided screen version. It's possible I may have some offcuts lurking but doubt anything long. I don't see why larger sizes should not be available.

Absolutely. For years I've been using cat2 onwards for balanced audio and some very long runs, For OB's it's been common to use 2 pairs for stereo feed, 1 pair for return audio & 1 pair for talkback, sometimes as the actual link but more usually as the run between studio/radio and OB/radio and they may often be hundreds of metres. Years ago I made up some boxes with 4 XLRs and RJ45 for 'stage snake' type use then added a switch to some to use pair 4 as the common ground for phantom use. Just recently I repurposed a male end which was simply 4 thin FSTs style terminated in a RJ45 plug and male XLRs.

I started looking after I'd posted yesterday, I see a selection of models, are there any better/worse than others? The usual camera I've been using for a long while was a pretty good CCTV camera 20 years ago, I think about 350TVL and TBH most of what its used for the momentary white/black out doesn't really matter that much unless there is significant flashing. As I'm claiming to have retired I'm not looking to invest much😉

Cleared a shelf today, these bits are going on ebay tomorrow (Monday) PM while I have 80% offer Soundcraft power supply - CPS 150 Alice Matchpak X2 Canford twin microphone pre-amp Tannoy TX1 system controller Kramer FC10 Composite/YC transcoder Drake 1U IEC 10 way power distro - 10A max with 5m mains lead and 16A CEEform SCV universal balanced/unbalanced interface - includes: 3* VCA/AGC (unbalanced), 5* in/out, 1* 4unbal in to 2balanced out, 1*PSU Most unused since my last OB >10 years ago, just done very basic tests to confirm working and all have scratches from a working life. Open to offers.

I have regularly put show relay in for village hall type shows, mostly to dressing rooms where latency is irrelevant, initially using 21" CRT TVs and composite, often running over cat5 with baluns. One venue had 19" flat monitors and VGA over cat5 receivers in place so sourced the same system from CPC and converted to VGA. despite being smaller the actors seemed to prefer the flat screens and found myself running VGA on 19" flat screens more than CV on bulky CRTs. However a trip to the local tip at TV Digital switchover quite by chance I parked beside a vehicle from which a 15" and 19" analogue TV were being removed, the jobsworth staff member tried to argue I wasn't allowed to take them despite not even touching the ground, literally a direct vehicle to vehicle transfer and during that another person offered the 19" he was about to dump. Those 3 plus another 19" aquired since are my usual stock for such, occassionally 32"s/40"s from home when required but rare. Do I regret disposing of CRT stock? Only once as relay to MD from SM feed. At one point both could be seen wiyh significant latency to MD. I did try using a CCTV cat5 system... Yeah right, never again. As far as I'm concerned it's analogue all the way, I just wish I could find a camera to cope with the dramatic light changes better.

I have had a couple where one output transistor has gone s/cct C to B (effectively a diode between C&E) which seems to 'work ok until the volume is cranked up', or so the docket says.

All sorted, luckily the double sided pcb (containing 2 pots each and linked with 3 pin jumper leads) are laid out in such a way that cutting 2 tracks by each pot and soldering a link across the pot pins was easy. Input resistance is 6* 10K+10K in parallel = 3K33 I know it shouldn't but that arrangement seems to work more 'linearly' than just one such control. This came from AliExpress at a total cost including delivery under £7 with a white stripe to write on and took 20 minutes from the time it came through the door to modify and test. Yes it's cheap but at the moment it seems to be useful, even the XLR's feel OK. The only downside that I can see is it's only 58mm deep so can be very deeply buried when it comes to access for plugging.

These are for S4 & S4000: The shorter (top) aerials are for CH70/higher frequencies, the longer (bottom) aerials are for CH38/lower frequencies. I assume other systems follow the same format.

Thank heavens I'm not the only one to have this thought.

I was surprised the first time I used an impedance meter just how efective it is for the purpose, did you think the same? PM sent

As has been said any amplifier will do. I did exaclty this exercise in a shopping centre fitted with 32 zones of voice EVAC. Initially we tried locating failed speakers using the main system (450W per zone) but lack of volume control capabilities made it difficult. we used a small amp of around 30W at 8ohms to provide a low level signal on a zone by zone basis. The thing about such a system is if properly designed there are no apparent gaps in the sound but running at a much lower level allows the gaps to form. As Philip has mentioned the tone set may be enough for the job, the same is true for a loudspeaker impedance meter. As an aside to this I'll shortly be sorting out my 'store' and disposing of my PA hire stock including a number of 120W mixer amps, typically TOA A512 sort of thing if it helps. EDIT: Another aside: I've been using Eagle horn loudspeaker for 50 years 100V tapped at 15W and regularly run a row of them on a 120W 4ohm amplifier without a step-up transformer.

Me, Me🤫 Initially I had 2* 21" tv's to do show relay to dressing rooms, then used 19" VGA monitors, with CV to VGA and VGA to CAT5 adapters. Taking one of the TV's to the tip I was really lucky someone was dumping 2* 19" flatscreen analogue TV's a few days after digital changeover and used those ever since. I tried using TV internal speakers but find it's much easier with Fostex powered speakers.