Compresson Driver availability

[Bruce Weldy]

Bill,

The F151M-8 is not available right now and won't be for some inderterminate time. It will probably come back at some point, but there is no ETA from Eminence.

Are there any possible alternatives for the 1.2k crossover option? The PSD 2002-8 are about twice the weight and 5.25" x 2.2". Is it a possiblility? Or, is it too big to fit in a DR280 (or any other boxes)?

[Bill Fitzmaurice]

Any driver with comparable specs to the F151, including size and weight, will do. Don't rely on catalog descriptions, look at the data sheets. That automatically excludes cheap drivers that have no data sheets.

[Bruce Weldy]

Any driver with comparable specs to the F151, including size and weight, will do. Don't rely on catalog descriptions, look at the data sheets. That automatically excludes cheap drivers that have no data sheets.

That pretty much takes Eminence out of the running.....can't find any of their products that are that small with that frequency range......with the exception of the N151-8, but I seem to remember you saying not to use that one?

They do have some leftover NSD2005-16. But, that would require a different crossover design. However, if anybody wants 'em, they will sell 'em really cheap to get 'em off the shelf since they are discontinued. If you want 'em, let me know.

[Bill Fitzmaurice]

A pair of NSD 2005-16 can be wired parallel for an 8 ohm crossover. Double the capacitor values, halve the inductor value. The low pass filter is unchanged.

[Bruce Weldy]

A pair of NSD 2005-16 can be wired parallel for an 8 ohm crossover. Double the capacitor values, halve the inductor value. The low pass filter is unchanged.

Thanks Bill.

Out of curiousity......which 3rd order crossover variation are you using? Bessel? Butterworth? I was trying to figure it out on my own using a crossover calculator and couldn't come up with the same values as the crossover for my OT12s. Do you make some adjustments based on the output of the woofer and CD?

[Bill Fitzmaurice]

It's not a textbook crossover. I adjusted it to give the best results. There are only a few textbook crossovers, identifiable by their Q. Simple calculators only offer the usual Q choices, to keep things simple. You don't need to use a given Q, you can use your own. It's like speaker modeling software. When modeling a box they offer a few stock alignments, also defined by their Q. That made things simpler back when we did our calculations from formulas with slide rules or graphic calculators. But you don't have to use a stock alignment, you can create your own, with any Q you wish. The software makes it simple, as you don't actually have to do any manual calculations.

[Bruce Weldy]

It's not a textbook crossover. I adjusted it to give the best results. There are only a few textbook crossovers, identifiable by their Q. Simple calculators only offer the usual Q choices, to keep things simple. You don't need to use a given Q, you can use your own. It's like speaker modeling software. When modeling a box they offer a few stock alignments, also defined by their Q. That made things simpler back when we did our calculations from formulas with slide rules or graphic calculators. But you don't have to use a stock alignment, you can create your own, with any Q you wish. The software makes it simple, as you don't actually have to do any manual calculations.

Kinda' what I figured. The calculator was close on some values and further away on others. If you (well, not you - but a novice) were to use a calculator for a two-way box, would you use Bessel, Butterworth, or LR? I know there are a lot of other factors, but is there a reason to start with one over the other?

[Bill Fitzmaurice]

You can find on line charts that compare different Q values. I prefer somewhat higher than the 0.7 of Butterworth.