The Boogie Man Posted November 4, 2006 Share Posted November 4, 2006 Hi all,I'm putting together some cabs and just wondered about a couple of things,I've seen on a couple of adds for comp drivers on ebay "piezzo design no x/over requied". could someone explain the difference between this design and a diapham design? Also, if a speaker driver is rated 4ohms then the amp sees 4ohms, if a passive x/over is placed in line does it also have to be 4ohms along with the comp driver that the hgh end is split to? ie would an 8ohm x/over make the amp see an 8ohm load? or would it still see a 4ohm load.cheersbaz Link to comment Share on other sites More sharing options...
paulears Posted November 4, 2006 Share Posted November 4, 2006 piezo type HF units are quite happy with a full range signal applied, but only function in their pass band. One by product is that they have a tendency for rather 'sharp', cutting HF - can't really describe it, but not at all 'smooth'. They are quite cheap compared to a proper compression driver and are very popular in disco quality kit (slur intended). A passive crossover is just designed to have an input impedance that matches the amp, and outputs to match the speakers. Most have these specs available so you can check. what they don't tell you is how they match the speaker drivers - so buying an HF and LF unit, and crossover might mean it hf heavy or light, which then needs more eq to sort out. Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 4, 2006 Author Share Posted November 4, 2006 Cheers paul, I'll stick with the diaphram comp drivers I've got then. Do the diaphram type work in the same way as a cone type driver, ie they have an rms wattage and a progam wattage? The type I have are celestion rtt 50's 8ohm from the road system, so Iwas wondering can they handle 100 watts program if it's after an active x/over sending them only a signal above say 1-2khz?cheersbaz Link to comment Share on other sites More sharing options...
paulears Posted November 4, 2006 Share Posted November 4, 2006 I'm trusting my memory, but I have an idea these things were rated at only 25W or so? editjust found thisRTT 50 RING TRANSMISSION TWEETERCouples the new Celestion ring diaphragm to a rectangular horn, giving a wide operating range particularly suited to two way systems.IMPEDANCE 8 0R16 0hmFREQUENCY RANGE1.5 kHz -15 kHzSENSITIVITY101 dB SPL FOR 1 WATT AT 1 MAMPLIFIER REQUIREMENTUP TO 50 WATTSFLUX DENSITY1.15 TESLA VOICE COIL DIAM. 38 MMRECOMMENDED CROSSOVER FREQUENCY1.5 kHz (18 dB/OCTAVE)DIMENSIONS (OVERALL) MM110 x 220 x 140 (165) does this help?paul Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 5, 2006 Author Share Posted November 5, 2006 Cheers paul, It does. So how are these drivers surviving having nearly 600 watts pumped into them? Does the crossover limit the power to them or are the frequencies not harmfull to the driver above 1-2kz?cheersbaz Link to comment Share on other sites More sharing options...
paulears Posted November 5, 2006 Share Posted November 5, 2006 the crossover networks also reduce the hf power to something quite reasonable. It just goes to show how inefficient LF drivers actually are! Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 5, 2006 Author Share Posted November 5, 2006 Would an active x/over do the same? I was thinking about going three way mono and putting two of these drivers ( to give me 40hm ) in a box after the x/over, but the amp Iv'e got is nearly 300 watts. would they last more than a nano second?cheersbaz Link to comment Share on other sites More sharing options...
paulears Posted November 5, 2006 Share Posted November 5, 2006 No - they don't (although to be fair most could be programmed to) but it isn't necessary. I have a 3 way active system and it has 3 amps, all quite cheap ones - a 3200 for the subs, a 2400 for the mids and a 400 for the HF. Balance wise, the input controls are set at full for the subs, about 70% for the mids and about 80% for the hf - this balances out quite well, tonally - I then have the levels set so that clipping on the desk is just a tad below clipping on the amp. I could adjust the crossover to allow all amps to be set full which is the usual way to do it, but as they get set and left (I don't even bother doing the turn down before powering up sequence), they work fine.Paul Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 5, 2006 Author Share Posted November 5, 2006 Your system looks very similer to the one I'm putting together, Mine is a matrix 1600 into celestion 4oo rms 15" low, matrix 1300 into celestion 250rms 15" mid, and studiomaster 700d into two rtt50's high. You think the studiomasters 350 into the comp drivers will work?cheersbaz Link to comment Share on other sites More sharing options...
paulears Posted November 5, 2006 Share Posted November 5, 2006 I'd be worried that you have too much power available here - but the drivers you have are not over specified, power wise, meaning it would be quite easy to overdrive a single pair - mind you if you were careful with output level on HF and do the alignment carefully you should be fine - after all, a big amp running gently is always better than a small one flat out. the crossover frequency is also important - if the mids go up high enough, you have a wide choice of frequency and eq slopes to make it sound nice. Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 6, 2006 Author Share Posted November 6, 2006 cheers paul, the sound going in is just me ( acoustic + vocals ) and the range is only between 80htz and 6-7khtz, so the high will only be to add a bit of sparkle on top. I think for safety though I'll source some bigger hf drivers. cheersbaz Link to comment Share on other sites More sharing options...
jamesperrett Posted November 6, 2006 Share Posted November 6, 2006 So how are these drivers surviving having nearly 600 watts pumped into them? Does the crossover limit the power to them or are the frequencies not harmfull to the driver above 1-2kz? The simple answer is that you aren't actually pumping that power into them. Most types of music have much less energy above 2-3kHz than below. That's why HF amplifiers and drivers are less powerful than LF amplifiers and drivers. There is also the question of efficiency. 101dB/W is more efficient than most LF drivers so you need less power for a given sound level. A well designed crossover will account for the differing driver efficiencies but a general purpose passive crossover will probably assume that all drivers are the same efficiency. Of course, if you deal with signals with a strange spectral balance with unnaturally prominent HF (like clipping or square waves) then you'll need drivers with better HF power handling. Cheers James. Link to comment Share on other sites More sharing options...
The Boogie Man Posted November 6, 2006 Author Share Posted November 6, 2006 cheers James. On a related note, the cabs I've built don't have the mf driver at the front of the cab, it's now set about 300mm back and the sides are angled out from the sides of the driver to the end of the cab.(long throw, I hope). Is there any advantage (or drawback) to placing the horn in the centre of the cab in front of the mf driver. I thought it might mean that the cabs could then be either stacked or flown or used individually and still retain a full sound.cheersbaz Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.