A cautionary tale... and some speaker driver advice needed

[dicky]

This afternoon I set up for tonights disco..... and found I had no sound

Basically I could see I have signal going into both Crown amps (signal LED flashing) but nothing coming out of the speakers - not even a hum or a hiss

After a considerable amount of messing about trying to figure all this out I went back to my unit and picked up my spare W Audio amp and while I was at it put my spare Peavey Hisys 15" cabs on the van. Iwas given these for nothing by a local pub and fixed both of them - even got inside the voice coil on one to fix a bad connection!

I drove back to the venue, only about 5 miles but the traffic was bad what with the bank holiday starting. :rolleyes:

Anyway, plugged in the spare amp and got nothing still. Tried bypasing the mixer, the CX23 crossover - nothing. I was just about flummoxed but then I remembered I had a multimeter on the van. Checked the reading on all four speakers and found they are all reading open circuit.

Got the Peaveys, connected them to one of my Crowns and then I had sound.

Now I wondered how can I possibly have four open circuit speakers... all worked last time I used them. Then I remembered the weekend before I went to Gran Canaria I had a booking in a little pub and it wasn't brilliant money - then a guy from a venue I play regular called me up and mentioned he had a DJ playing from vinyl that weekend who wanted to rent some lights and a PA. The money was practically what the little pub wanted to pay me so I gave that booking to my mate and let the other DJ use my kit so I could have an easy night. I set up the kit and picked it up next day.

Now the next day the manager at the venue where I rented told me the previous night had been a really good one and I thought no more of it.

But it would seem I now have four blown speakes :Censored::Censored::Censored: How this happened I can't imagine as it is not a massive venue and I don't treat these speakers gently by any means, in facty I have played big halls with them, so they have plenty of power to more than fill that room.

OK so I had enough backup kit to get over tonights problem and my next booking is one week today (the venue where I often play and rented) and I need a bit more power for that so I need to sort this mess out.

So I just had a quick look at the Class D tops.

One of the 15" driver cones is jammed solid, the other one was jammed but I pushed on it and freed it however it reads open circuit.

Both the horn compression drivers work OK

The capacitors which feed the horns on the crossover now look like the attached picture!!


So a couple of crossover caps is less than a fiver.
The horns are OK
I need to replace the 15" drivers. Unfortunately there is no brand marking on them so I don't know what they are (or even what impedance they were but I imagine they are 8 ohm same as the horn drivers)

As I see it I have three options here

1. Take the Black Widows out of the Peveys and put them in. I am not as keen on the sound of hte Peveys as I am of the Class Ds
2. Use the Eminence 15" Drivers I got out of the old Peavey Subs that Peter (Excalibur) Sold me. I am not sure what model they are or if they are suitable, will have to check the spcs of them tomorrow. I think they may be Eminence Kappa
3. Buy some new 15" Drivers. I don't know what the original drivers are but they don't look particularly special or powerful judging by the magnet size and weight - again see pics

The QTX subs are not such a problem - I can get second hand 18" drivers for £20 each

So advice please :)

Rich

[Nakatomi]

Ouch Dicky that's gonna hurt.

Looks like somebody's been a very very naughty boy. I tell you man, some DJs (playing vinyl or not) don't have a flipping CLUE when the speakers are telling them STOP WE'VE HAD ENOUGH! I used to manage looking after a club's PA, both on the ground floor where I installed & worked and upstairs. I put in an EQ, which was inside a LOCKED BOX, got everything sweet as anything.. and at the halfway point in a night I had a barman pulling on my arm to go upstairs to fix the sound. Nothing I could do. The EQ box had been smashed to bits to get inside it & hoof all the bands to maximum (even 20Hz which I deliberately took all the way off).. and the speaker cones of 4 18" drivers were pushed out past their excursion & stuck there. I honestly could have glassed the 'guest DJ' for doing that.

No idea how you're gonna find out what drivers to replace them with Rich.. but maybe before hiring your gear to anybody ever again put fuses inside the speakers just after the socket eh? ;) (and NO, don't use panel mount fuseholders). Let the buggers blow & be silent :D


Edit: Better get in touch with Class D I think.. 01623 654080

[dicky]

Ooh thanks

yep I think I learned my lesson

I didn't know Class D were still in business

Rich

[Nakatomi]

Ooh thanks

yep I think I learned my lesson

I didn't know Class D were still in business

Rich

If I had a quid for every time I've heard a PA stretched beyond its limits, I'd be running on an HK Actor system by now :lol:

[Excalibur]

Dicky, you haven't wrecked my beloved Class Ds have you?? :cry::cry::cry:

That's got to take some doing, cos we both know what they'll shrug off and keep going. Right, the Kappas are LF, low frequency. From memory they're 4 ohms, but memory's hazy. I don't think they're well suited to mid high use, I bought them for use as subs.

The original drivers are 8 ohms, 350w RMS rating.

Wallet friendly Eminence Beta. (http://www.bluearan.co.uk/index.php?id=EMIBETA15A_2PK&browsemode=manufacturer)

Delta (http://www.bluearan.co.uk/index.php?id=EMIDEL15A_2PK&browsemode=manufacturer) looks a better match.

Decidedly wallet unfriendly Kappa (http://www.bluearan.co.uk/index.php?id=EMIKAP15A_2PK&browsemode=manufacturer)

I'm only going on paper specs here, I've no idea which would suit the boxes best.

[DJ Jules]

By the sounds of things you've encountered a DJ who has no clue about gain structure. Sadly you don't need to run cabs hard to fry the voice coils, you just need to feed them DC, rather than AC - i.e. you just need to run one component of your system consistently in the red and the voice coils will get all the current, but none of the movement needed to cool them. The coils melt, and you get the lack of movement you've seen here. Frying the caps is impressive though, that does usually imply over-voltage (i.e. running them too loud).

If you're going to hire out kit, make sure they're active cabs and have DSP as most processors will protect the drivers from this kind of stuff.

[Nakatomi]

By the sounds of things you've encountered a DJ who has no clue about gain structure. Sadly you don't need to run cabs hard to fry the voice coils, you just need to feed them DC, rather than AC - i.e. you just need to run one component of your system consistently in the red and the voice coils will get all the current, but none of the movement needed to cool them. The coils melt, and you get the lack of movement you've seen here. Frying the caps is impressive though, that does usually imply over-voltage (i.e. running them too loud).

If you're going to hire out kit, make sure they're active cabs and have DSP as most processors will protect the drivers from this kind of stuff.

Yeah but it's still gonna sound really horrible well before the speakers give out innit.

[ckpr2]

It looks as though your speakers were absolutely hammered.
He needs his butt kicking.

Touch wood, never blown a speaker DJing in 38 years.
I try to protect my speakers as much as possible.
I have a DC protection system on my amps in case the amp blows and puts out DC.
But this wont protect against over driving the speakers.

[Excalibur]

Edit: Better get in touch with Class D I think.. 01623 654080




I didn't know Class D were still in business

Rich

You are correct Dicky, to the best of my knowledge they aren't. :( I don't know what happened, but they slipped off the radar a few years ago.

[DJ Jules]

Yeah but it's still gonna sound really horrible well before the speakers give out innit.

Yup :) Apparently that's not enough to stop some DJ's...

Julian

[dicky]

I completed last nights gig without any further problems using the Peavey Hisys 15" cabs

Actually I was pleasantly suprised, as I mentioned earlier I was given these by a local pub as they were going to go in the skip

One of the Black Widow drivers had the voice coil rubbing and I fixed it by unbolting the magnet and rotating it to a different position then bolting it back on

The other one had an open circuit at the top end of the voice coil where the copper strip connects (this then connects to the braid that goes through the speaker cone to the terminal). To fix this I had to carefully cut away the dust cover (the domed cardboard thing in the bottom of the cone) to get access to that end of the voice coil, then resolder it and glue the dust cover back into the cone.

I tested them after this but I never had the chance to run them at any sort of meaningful volume and never quite trusted them. so they were sitting in my storage unit awaiting decision what to do with them.

Anyway due to necessity my resurrected Peavey Black Widows did a great job last night to a room of around 100 folks without my subs - and now I do trust them. I am thinking of making some badges that say 'Lazarus' to put on the front!!

Back the the amps/speakers
When I rented out this kit he had my amps and four speakers plus booth and half a dozen lights

The Crown amps seem to be fine - I used one of them last night to drive the Peaveys and the other one powers up and looks like it is working fine though I didn't connect any speakers to it. However i have no doubt they are both OK.

I haven't looked at the 18" subs yet but I suspect they have blown drivers as there isn't really anything else to go wrong - they don't have crowwovers as I use an active CX23. Anyway they are QTX/Citronic drivers - not expansive and I can probably get a couple second hand working ones cheap.

Alternatively some of you may recall I had my hands on some vintage home built 18" Fane Collossus cabs which I took to Coalville earlier this year. I don't have them anymore as the cabs were badly designed and totally not suited to the drivers. But all turrned out well as I kept the Collossus drivers, re-engineered the cabs to have some reflex ports, fitted two of the Citronic 18" drivers, put them on ebay auction at 99p start and got the same I payed for them with the Fane drivers in - £200. Actually they sounded good once I had reworked them and the buyer was very happy. So basically I got a pair of Fane 18XB drivers for free.

I used some of the money to get the local timber merchant to build me a pair of these cabs from 18mm birch ply (and I still had £70 change) http://www.fane-international.com/downloads/Cabinets18inch200Lres.pdf

I used the fixtures and fittings off the Pevey subs I got from Pete (this is why I have the 15" Eminence drivers on one side)

Basically now these cabs just need painting (have a local body shop who will spray them in textured black paint for £30) they need lining with underlay (good stuff for acoustic dampening and I got a load of offcuts from the local carpet shop) and need the drivers fitting. So at a push I could use these next couple weekends. What they really need though is two speaker grills - and idea where i can find a suitable supply of perforated steel for these at a sdensible price? They are about 60cmx70cm... give or take


Ordered the two 225K crossover caps today .

Just the 15" drivers to sort now - I beleive Peter can help me out there. I'm really glad I am on this forum guys :)

Cheers
Rich

[dicky]

Dicky, you haven't wrecked my beloved Class Ds have you?? :cry::cry::cry:

That's got to take some doing, cos we both know what they'll shrug off and keep going. Right, the Kappas are LF, low frequency. From memory they're 4 ohms, but memory's hazy. I don't think they're well suited to mid high use, I bought them for use as subs.

The original drivers are 8 ohms, 350w RMS rating.

Wallet friendly Eminence Beta. (http://www.bluearan.co.uk/index.php?id=EMIBETA15A_2PK&browsemode=manufacturer)

Delta (http://www.bluearan.co.uk/index.php?id=EMIDEL15A_2PK&browsemode=manufacturer) looks a better match.

Decidedly wallet unfriendly Kappa (http://www.bluearan.co.uk/index.php?id=EMIKAP15A_2PK&browsemode=manufacturer)

I'm only going on paper specs here, I've no idea which would suit the boxes best.


To be honest none of them are silly money - but how would one decide the best match?

[Excalibur]

To be honest none of them are silly money - but how would one decide the best match?
You'd do as I suggested, ring the white haired old git in Yorkshire, and come to a deal on some " pre-loved " Class D cabs. :whistle::whistle:




For readers who haven't spotted it, subject to finding a suitable meeting place, a deal has been done which both parties are happy with, and Dicky will soon be the proud owner of some more Class D cabs which will not only furnish him with the required drivers, but also allow him the chance to recycle some of his other kit.

[dicky]

Correct - the deal has been done

Can't fault this forum and in partcular I can't fault Peter :beer1::beer1:


Can't wait to see what those Fane Collossus 200L cabs will sound like either ;)

[ckpr2]

Can't wait to see what those Fane Collossus 200L cabs will sound like either ;)
I have always been a big Fane fan.
My first disco used 4 50WRMS 12 inch drivers. They were very loud and sounded great.
I later sold the disco and they went with that.
I got into other makes but was never happy with them.
I went back to Fane in the end.
I now have a house full of Fane speakers in my own cabinets.
Fane 12-500 in a bass reflex cabinet.
Fane 15-400 in a folded horn cabinet.
1980's Fane 12-50 in a folded horn cabinet.
Fane 15-600 pro in a folded horn cabinet.
2 off Fane 12-100 in a sealed box.
Fane 10-300 pro in a folded horn cabinet.
4 off Fane 10-225 in a sealed cabinet.

I buy my speakers from www.bluearan.co.uk
If you join their jam club you get a small discount on what is already the lowest price I could find.

[Nakatomi]

I could almost be tempted to have a go building my own bins. Maybe my own tops too, but that wood stuff weighs a bit more than I'm prepared to lug around on my own & I'm only ickle. Then there's the amps. Good uns still weigh a bit don't they?

[ckpr2]

I could almost be tempted to have a go building my own bins. Maybe my own tops too, but that wood stuff weighs a bit more than I'm prepared to lug around on my own & I'm only ickle. Then there's the amps. Good uns still weigh a bit don't they?

You can buy amplifiers with switch mode power supplies which are much lighter than transformer power supply amplifiers.

[Nakatomi]

You can buy amplifiers with switch mode power supplies which are much lighter than transformer power supply amplifiers.

I know that but are they any cop? I've never worked with class D amps apart from those in active speakers. I suppose when you're already humping great big lumps of wood about an amp flightcase is probably a drop in the ocean.

[Excalibur]

I suppose when you're already humping great big lumps of wood about an amp flightcase is probably a drop in the ocean.
Mine aren't. :( I finally admitted defeat, and the only power amp I have left is for the big subs. I had to let some lovely W Audio Epics go, cos the amp was just too heavy to carry about.

If I could have got a couple of Peavey IPR amps, it would have been different, and I'd still be running them.

[dicky]

Justin
You can get amps with Switch Mode power supplies that are not Class D.

They will be Class B or Class G (Maybe even H) For example the Crown Pulse 21100 amps that I run are of this type.

So what you have is a conventional amp with Mosfet or Bipolar output stage, but with a switch mode power supply rather than a massive heavy toroidal transformer. This does reduce the weight considerably.

If you get a Class G or H with a switchmode you end up with an even lighter weight conventional output stage amp as these either switch between two voltage rails - typically 48V/92V - depending on the output amplitude of the wavewform at that instance in time (Class G) or they have contunually variable power supply rails that are always just a few volts above the amplitude of the waveform (Class H)

IN either case the heat dissapation is much less than a Class B and so they have much lighter heatsinks and still run cooler.

Rich