Jump to content
Dj's United


Community Leader
  • Content Count

  • Joined

  • Last visited

Posts posted by norty303

  1. I dont want the OP to assume that a 100W speaker will magically become a 150W speaker by shoving 150W through it. It will still be a 100W speaker!


    Absolutely, but I think there is value in detailing why the numbers don't equate equally between amp output and speaker RMS rating, how musical signal is different from test sine waves, how speaker ratings are actually devised, etc, etc


    Unfortunately it's a big subject, but I think dumbing it down only leads to misinformation and misunderstanding about what is 'safe' and what are the causes of loudspeaker failure.


    I think if there was one thing I'd advise anyone, it's 'do not clip your amps'.

  2. If your top cabs are rated 100W, then connecting them in parallel with 200W bass bins will mean you must restrict the output to 100W...so either underdrive the bass bins (wasting money) or overdrive the tops (and possibly overheat them).


    No you don't really, unless you're going to go start playing sine waves through the rig.


    150w into a 100w rms rated cab should be fine so long as you don't go clipping the amp.


    Even running flat out the average power the speaker is likely to see will be 90w or so.


    'Restricting the output to 100w' would be just about impossible anyway.

  3. it used to be possible,. but nowadays, so many cheap and different stands out there, i doubt its possible.


    Of course its possible.


    Speakers will usually use a 35mm top hat, and 35mm is becoming more normal for lighting as well (specifically because people want to mix and match their stuff and the less pro companies wanting to only have to make 1 size for all their products)


    Lighting used to be 32mm or 29mm standard connectors depending on brand (Powerdrive, Manfrotto, etc)and intended use (follow spot spigot, etc)


    You can now get a wide range of 35mm adpators, t-bars from lots of manufacturers that'll do what you need.


    Google 35mm t bar or anything 35mm stand related to get a long list of what you might find useful.


    The only time you'll need to be careful is if you have a specialist type/brand of speaker stand and their own bespoke top hat/adaptor. 2 mins with a tape measure will tell you that.

  4. Also the particular wavelength of a colour is very significant to brightness.


    For greens you're fairly limited to 532nm (for common affordable DPSS), and this is the most bright to the human eye for a given power.


    There are a range of reds available now 635, 642, 650 and 660. I've just bought a 1.1watt 650nm head and a 635 of about half the power will be as bright, but much more orange. 660 are very deep blood red but require silly powers to see (and hence more dangerous)


    Blues come in a few options, 473 being the most popular as its brighter for the money, but is starting to get a bit cyan in colour. Blues are by far the most expensive of the 3 for a given power output. Be wary of cheap 'blue' lasers using 405nm bluray diodes. They are basically violet/ultraviolet and don't really do very much in a laser display. Be very clear what you are buying when looking at non-green sources as they can differ greatly between wavelengths.


    This is how the human eye sees the different wavelengths as far as brightness goes.




  5. Your average commercial nightclub will use a laser between 5 to 20 watts


    I think that may be overstating it somewhat. Perhaps in the old gas head days, but nowadays 2 watt dpss lasers are pretty impressive alone. It also depends on the size of the club.


    A 400mW 532nm (green) laser will adequately do a club of 300 or so.


    So as a rule , the higher MW the better?


    Well, more dangerous at least! But yes, brighter = better in the laser game, more defined beams, less smoke required to make them visible, 'WOW factor', etc


    Just be fully aware of the risks if you are in the market for a laser bigger than the average 'DJ' unit.



  6. To put it in perspective, the Void Infinite 8v2 is capable of doing 3800w per side at 2ohms. It has a digital readout on the front to indicate how many amps its pulling from the mains. People I know use this to see just how high they can get it as a form of racing...


    In normal use with 4 18" bass cabs per side playing bass heavy music like DnB and dubstep they tend to tick over about 6-8amps which is a lot lower than the theoretical 33A at 230v that you might expect. Thats not to say that they don't get up into the 20's but thats being silly and certainly well in excess of what you're likely to do at a disco.

  7. Amplifiers are, at best, around 80% efficient (depending on topology, some much less so), meaning that they will only ever put out 80% of the power they draw in....


    BUT capacitor banks have a large part to play in burst power which is why you see some crazy peak power figures on modern amps that exceed what could realistically be drawn down the power cable.


    Also, although your amp may be rated at 1000w per channel it is unlikely that you'll be playing sine waves all night at full power, so you won't ever draw 2400w with both sides of the amp running hard.


    Modern music has a duty cycle of between 2/3rds and 3/4 peak power so even running flat out you'll be putting out (and therefore drawing) significantly less than the rated value. If you have an active system then the bass will work much harder than the mid tops too so you can allow for that.


    We've run silly rigs off of single and double 13A sockets when required and they've been fine. We had 8 Funktion 1 F218's and 6 Res4's on MC2 amps running off a twin 13A socket last month no problem.


    I'd say if you regularly run flat out with the amps then use a number about 2/3rds of the combined channel output at the impedance you're running to calculate how much you can plug in. this will undoubtedly give you some headroom but thats always safer.


    Lights are another matter....

  8. I'd say that the evidence is fairly clear that it has been misused if the coil on the crossover is burnt out. They don't do that on their own with too little power.


    Sounds exactly what you would expect from a clipped amp - lucky no drivers went too (you have checked the drivers separately I take it?)


    You could get a replacement crossover for about £30 or £40 and fit it yourself, they're readily available, its just choosing the most appropriate for the job.

  9. At what frequency was that 101db/1w/1m measured?


    Manufacturers have a habit of picking the highest number even if it doesn't fall within the normal operating range of the speaker.


    However from looking at the graphs it appears that is within the usual range of the speaker (120hz-1.5khz)


    Worth bearing in mind if comparing against others

  10. Eminence are ok if you're on a budget, even some of their more expensive drivers aren't bad. However it's usually the case that once you get up near the £100 mark and above there are better alternatives out there. That said, if an Eminence driver suits your cabs best then it'll be the best choice.


    Also, don't forget to look at the Thiele Small parameters of the driver and more importantly the sensitivity. You may find a driver with a bit less power handling but 3db better sensitivity which will be louder on your amp than the current one.

  11. be carefull on there power ratings,i have a friend who recones speakers,there rms is is more like a peak rating,ie they may say 500w rms,when its more probably around the 350 w mark.


    I'd say their rms is exactly what they say it is.

    I'd be interested to know what lead him to that conclusion? Scientific destruction testing with test tones?


    Certainly I know of a number of people who use them in short bandpass horns and use more than 500w and have no problems whatsoever


    Just make sure you put them in a cab that suits them. Use BassBoxPro, WinISD or Eminence speaker designer (stripped down BBPro) to do a rudimentary model to at least check your port tuning suits them.


  12. We get a reasonable turnover of 2nd hand kit through the buying/selling section of our forum, and it's normally either good branded pro gear, or tried and tested stuff from the cheaper brands. As a pro-audio forum the members tend to steer clear of the cheaper disco marketed stuff unless it's one of the diamonds in the rough that exist (like the Berry EP amps for example)


    Not sure I'm allowed to cross post but I think my signature still has the address.


    In fact there's 5 separate threads on the first page today with amps for sale including Lab Gruppens, Crowns, QSC's, C-Audio, Matrix ranging from £90 up to £1500. Might be something there for you.

  13. To be honest, do you really need to know exactly what power rating it is?


    12" drivers at the budget end rarely top 200w power handling. If you work on the basis of a 200w cab then any amp up to about 300w at 8R should do the trick fine. you're only going to change the parameters slightly within that range, and not enough to really make much difference.


    If you post some pics of the actual driver chassis then we might be able to work out who the OEM is

  14. I'd guess about 200w total for the cab. If there are no measurements on the back of the 12" then measure the diameter of the voicecoil. This'll give you an idea of how much heat it can transfer, and therefore it's ultimate power handling. The bigger the coil, the greater the power handling. Exotic winding materials can make a difference here, but I doubt KAM will be using those... ;P

  15. never put phantom power on, unless you know what it is


    you could end up frying your mics or other equipment


    How so?


    What about desks that have global phantom power but don't use all condenser mics or passive DI's? Surely these desks would've destroyed lots of kit over the years they've been around if they could damage stuff if left on. The main reason for turning it off if not needed is to stop the popping you get when connecting and disconnecting kit.


    To be clear, correctly functioning phantom power will not hurt your regular dynamic microphones.

  16. The HSG95 (on which the majority of licensing authorities base their venue license requirements for lasers) has recently been made available to download for free after a decade of charging for it.


    I suggest you read a copy and get a sense of what it's talking about. It could do with updating really as a lot of the language is in relation to larger gas lasers, but it is equally applicable now.



  17. Oh really?!




    No nonsense at all proof is in the pudding all I say is try it with a budget amp you'll be suprised at the degrdation on some! Same for passive hi pass filters on subs for "leakage". Not got time for people who believe in using the subs crossover it's in-efficient - FACT! However. Simply cannot be bothered for "busybodies" trying to re-evaluate what I have given in advise to the original poster. Take it or leave it couldn't care less.


    The problem I have with this is that I have yet to hear anything remotely similar from anyone, anywhere, despite having the collective knowledge of many decades and emminent speaker and amplifier designers knowledge and experience to hand.


    What is a more common occurrence is for people to come to DJ forums and claim 'superior ears' with wild claims that they refuse to substantiate when called on it.


    Noisy pots or crackly pots, particularly as they age - yes. 3rd order harmonics - not yet I'm afraid.



    yes, passive crossovers do soak some power (re: inefficient statement) and I'm the first to advocate going fully active for improved sound quality and level, but 'leakage'? 12db/oct is 12db/oct however you read it, unless its designed as a lower or higher order, or the company mis-represent it (I know, we'll tell everyone its 12db/oct but really we'll put in those 18db/oct ones)


    unless you are suggesting that the OP bypasses the crossover internally


    Just for completeness in the thread, yes, if the cabs give you no external way to bypass the passive x-over then you should rewire direct to the driver if you are going to use an active crossover, or you'll start to suffer all sorts of phase anomaolies from the combination of shift providing by competing orders and frequencies

  18. I hope you'll forgive my scepticism about that, particularly the specifics of the 3rd order harmonics.


    Also, can you define 'leakage' in relation to passive filters? In my experience, they are what they are, with a slope as defined by the components. More expensive components will usually only make them more reliable and able to take more power, not change the characteristics of the crossover point/slope.

  19. otherwise you get a form of harmonic distortion when turning the amp gains down.


    Care to expand on this one then? I'm intrigued to know where this may have come from and what foundation it has in reality.


    Could you be referring to the fact people tend to drive the mixer harder with amp gains down thereby causing the mixer to distort? If so, I wouldn't really consider that a function of having the amp gains down...

  • Create New...