Can any1 confirm the horn length of 1850

 

It's about 4.66ms for 1.6m but you will need to subtract the delay of any speaker on top of the 1850 from that (provided they have a shorter path length/delay).

 

Say you have a mid horn with a 30cm path length; the delay on that is about 0.87ms, so the delay applied to the mid-horn is 4.66-0.87 = 3.79ms

 

Unfortunately it is not that simple. All speakers have what is called a 'group delay' regardless of the physical distance to the fron of the cabinet, this is also a delay but is a function of the type of speaker (BP/horn/reflex/sealed, etc) and the tuning. Even if you used the best tape measure in the world to calculate your delays, they would still be wrong, becasue you would not have factored in the group delay.

 

Unfortunately it is difficult to calculate group delay accurately, and so it is general practice to get the delay in the right ballpark through the type of calculation I did above, and then fine tuning the delays by ear to account for factors such as group delay.

 

If you learn how to use a measurement programme like SMAART, it can do it all for you, but I find it easier and quicker to do it by ear using the sine wave method. It is explained elsewhere on the forum but essentially you do the following:

 

1. play a sinewave at the crossover frequency between the two cabs you are setting the delay for, say an 1850 and a 12inch mid-horn.

2. Invert the mid-horn using your ultradrive/xta/driverack/minidrive, etc.

3. Get the delay of the mid-horn into the rough ballpark you calculated from the physical path lengths, and sweep the delay up and done, going backwards and forwards accross the approximate delay you think should be applied to the cabinet.

4. You should hear the volume of the sinewave going up and down, keep playing with the delay looking for the quietest point in the sweep.

5. When you are certain you have the quietest point, invert the mid-horn back to normal polarity and you should have the perfect delay.

6. If you are feelign anal, you could do the same again, but this time inverting the 1850. The correct delay this time will be slightly different. Any point between the 1st and 2nd delay times should be about right.