Crossover in modded x15

that is a very high crossover point for a 15" driver. you may find you need to fit some resistors in a configuration known as an "L-pad" to reduce the volume of the high frequency relative to the mid. worth a quick read on maybe.

Another thought; is it definitely the HF driver that is piercing?

You might find the 15" driver is peaky in the 1k-3.5k range and this is partly the cause of the problems.

I found the 12MB in our cabs is peaky in the 2-3k range; we use our Ultradrive to add parametric EQ and roll off the 12" driver somewhat before the 3.5k crossover point which makes it sound better.

I'm not familiar with the Blue Aran crossovers, but it is possible there is no Lpad used in them at all, which would certainly make your HF driver much too loud.

An L-Pad is only two resistors... if you can solder I reckon you could make one. In fact, with a few of those screw terminal strips (I call them chocolate box connectors, not sure what their proper name is) you could cobble something together without soldering.

All an LPad does is reduce the amount of power going to the HF driver. One resisitor is in series with the +ve connection to the HF driver, the second resistor is in parallel with the HF driver (see diagrams in Rog's excellent post on passive crossovers and lpads).

The LPad in the Fane crossover that they supply for use with the 12MB and CD150 uses two metal 5ohm 25 watt resistors (roughly an 8dB cut for the HF), which gives you a starting point to try.

Another possibility is a ready made adjustable LPad, which I've seen for sale. These allow you to vary the amount of attenuation (cut) applied to the HF.

It is normal to get some low level hiss from your HF driver - how much depends on how noisy the amp / mixer etc driving it are in my experience - older amps tend to be noisier. It shouldn't be noticeable once you have music playing, however. If you have another amp might be worth trying that to see if the noise is reduced / goes away.

I'm afraid I don't have any experience with adjustable L-pads, so I don't know if the one you linked to would be able to handle the power levels involved. I did find one rated at a slightly higher power rating here:

http://cpc.farnell.com/_/at-60h/high-power-l-pad-mono/dp/LS00547

Still only 100W rated though; I would imagine you will be driving your cabs with more than 100W, so I just don't know whether either of these options will be able to handle the power levels involved. Maybe someone else who has used these can chip in?

If not, I guess you could always buy one to try, and keep an eye out for burning smells!

EDIT: just occurred to me that I should have said, either the l-pad you linked to or the one from farnell will be effective at bringing the HF level down (at low power levels at least). The only thing I'm not sure about (as I said above) is whether they will cope if you are running the cabs hard.


Edited by colinmono - 16 February 2010 at 9:55pm

Lincoln1 wrote: This lpad would eat the power involved being 100watts. The comp that we are trying to pad is 50w aes, ie even less 'rms' watts.

Sounds like one of the adjustable l-pads is the way to go then. Once you've wired them up you should be able to tweak the HF level so that it is nicely balanced with the 15" driver.

Let us know how you get on!

Alreet!

Installed adjustable Lpad and it worked a treat. The level of the HF driver is now in tune with that of the bass driver, (had to turn the Lpad nearly all the way down though!).

Also worked out what the white noise was coming from the HF driver as it was still apparent when the Lpad was fitted. Turned out it was my mixer?? When the mixer was disconnected and a signal was put straight into the amp, the white noise dissapeared. Looks like a new mixer might have to be on the cards!

Hers a pic of the finished modded X15. Im quite pleased with the overall build and sound, as its my first time ever workin with wood, or building speakers!



Cheers