Lifting the Veil from the 2405

[Allanvh5150]

These things hate passive networks at the best of times. Go active and run it with a chip amp.

Allan.

[Ian Mackenzie]

It's nice to see the passion and engagement of diy audio happening

The fun part is also inviting friends over to hear the latest improvement

I can't make it for distance reasons but l did meet another Dad at kids football this morning who is a loudspeaker "nut".

[toddalin]

More work into this and I found that after "lifting the veil," I can now even "remove the make-up."

Using 0.27 mfd in parallel with the 0.56 mfd, but with a resistor between them to keep their actions separate and provide more attenuation for the 0.27 mfd, I found that I can "cascade" this high pass filter to bring in even more harmonics and clarity.

[ivica]

More work into this and I found that after "lifting the veil," I can now even "remove the make-up."

Using 0.27 mfd in parallel with the 0.56 mfd, but with a resistor between them to keep their actions separate and provide more attenuation for the 0.27 mfd, I found that I can "cascade" this high pass filter to bring in even more harmonics and clarity.

Hi tod,

it would be nice if You can 'sketch' final network revision, so if any of us want to use the results of your tedious work, can do it without too much hesitations.

thank You

regards
ivica

[toddalin]

I'll do a video that demonstrates the difference and add a schematic. But recognize that unless your monitors can duplicate these higher frequencies, (and assuming that the camera's microphone can do it) you won't get the full impact.

The idea is to be like a subwoofer. You don't really want to hear it until it's called upon. I've tried to keep it subtle as it is very easy to get carried away.

[toddalin]

The 2405's "unveiled." No eq is used in this playback.

https://youtu.be/FEbEw8XaB_I

[toddalin]

OK, I now have a YouTube video that demonstrates my crossover mods in action. Recognize that we are dealing primarily with an increase in frequencies above 10K and if you're not hearing a difference, it's probably because your monitors aren't reproducing it, or your ears cannot hear high enough to pick it up. I can hear the difference on my Advent computer monitors, though, not quite like in "real life" and not of the quality. This may still be a bit bright, but it is easy enough to tone down through resistor selection, or replace the resistor with pins 1 and 2 of an L-pad.

If you can hear it, it will be obvious from the video when it is on/off. Note that I picked a piece with acoustic guitar and voice to demonstrate that this is not only for cymbols and synthesizers.

No eq of any type was used in this recording and we are just hearing the two JBL L200/300s with some fill from the subs.

https://youtu.be/ybaHiLMTws8

[toddalin]

Revisions to show modifications and the Ultra High component:

C1 and L1 and L-pad 2 form the basis of the N7000/N8000 crossover. R6 is the 20 ohm resistor across the tweeter leads used in later JBL offerings.

R4 and R5 form the voltage divider that reduces the volume a bit so that the high frequency component may be mixed in.