I have a EV 30w it is a 30inch sub woofer. It is neat as heck. It is vintage and in great condition. I do not have a cab for it and I must make one. I think I want to make a nice visually appealing cab for it verses an industrial concert looking one. I have plans for a 46.5 cubic foot enclosure but will that be optimal for this dreadnought or should it be bigger. Here are some specs on this amazing piece of audio history. Any Ideas ?
resonance; 15Hz +3Hz
impedance;
nominal 8ohms
minimum 5ohms
D C resistance 4ohms
101 db 1w/1m I think
I think it is 160 watts which is back then which means like 500 0r 600 now
EIA sensitivity 54db
Voice coil diameter 2 1/2 inches
magnet 9 lbs 4oz ceramic
net weight 34lbs
Do you have the model number of that driver? We need the Thiel/Small parameters of that driver. Without that data we can not help you. If you have the Thiel/Small parameters please post them.
You are wrong about old watts being different to new watts. They are the same, it is a 160 watt driver.
I think I have memories of that driver. I think it is a low Qt driver and only suitable for use in an enormous horn for auditorium use. I don't think that driver will do much in a ported or sealed enclosure.
The sensitivity of those older drivers is much higher than modern ones. The reason is that there is an inverse ratio between low bass output and magnet flux. Now in times past there where no high powered amps, so the drivers had to be sensitive and efficient. However, their bass output was poor, and the bass output had to be augmented with horn loading, so that there was useful bass output.
I bet that drover has a large paper cone and a relatively stiff suspension.
Modern subs, have a heavy cone and a loose suspension and low magnetic flux, compared to the older ones, and are generally 12 to 17 db less sensitive then your driver. So if you driver was fully powered with its rated 160 watts, then the spl would be roughly equivalent to a modern sub driven with 1280 watts! Or to put it another way, your driver in a properly constructed horn would produce the same spl from a 10 watt amp, as a modern sub with an 800 watt amp. I think this is where your misunderstanding may have come from.
In order to get any performance from that sub, an exponential or tractrix horn is going to have to be designed. It will be enormous if you want to reach the last octave. At an estimate, the horn mouth will have to be about 12 ft across!
I have only ever done a couple of horn systems, so I'm by no means an expert. An individual named
Dr Bruce Edgar has advanced the mathematics and understanding of horn loading over the last 20 years.
If you are really serious about this, he may assist you. Horn speakers are the most difficult to construct.
Unless you are planning to use this driver in an auditorium or old cinema, I think you can forget using this driver. It will be totally unsuitable domestically, unless you want to build one of those mad systems where the horn starts under your front or back yard and a wall of one of your rooms is the horn mouth. Yes, people have built such speakers, and more than a few, but they really have to be pretty high, yes worse than me, on the eccentricity index.
