JBL 2380 Horn

[Dr.db]

Hey guys,

I´m going to use the 2380 horn on my 2445 drivers.
I have a JBL M553 activ-crossover and will highpass them at 500hz and lowpass them at 9khz... This should be perfect, shouldn`t it!? Above 9khz is a 2405....
I´ve read somewhere, that I need some sort of special equalizer for some of JBL`s Horns... Can you tell me anything about that ??

Thanks a lot,
Olaf

[speakerdave]

I believe the manual for that crossover will show you how to set it up for the equalization you need. You can also use the 5235 and the FFBREQ card for the frequency you want.

[macaroonie]

Hi Olaf , you will need this :

http://www.audioheritage.org/vbulletin/showthread.php?19654-M553-mods-for-3-way-with-slot-tweet&highlight=

Also you may find that 650 is better with the 2380 but you can find this out yourself once you have the M553 set up. You must make the modifications to the 553 though.

Mac

[Dr.db]

Thanks a lot for your promptly replies :)


@ speakerdave:

I actually havn`t any manuals for the crossovers... But they just have high- & lowpass filters, no EQ section like +-12db @ 63hz, 80hz, 250hz, 1khz and so on...
I understand the way this unit works, but I thought I´d need some sort of additional equipment for the midrange-driver to compensate some issuese of the biradial-horn.
Or isn`t there nothing but the propper high- & lowpassfilter...!?
I hope I havn`t confused you now... :)


@ macaroonie:

Thanks for your vivid link.
But I forgot to mention, that I actually have two M553 crossovers and run them both in mono, so Highfrequency cutoff is @ 9khz.

[macaroonie]

http://www.jblproservice.com/pdf/M-Series%20Electronics/M553.pdf

https://www.jblpro.com/pub/obsolete/M553%20Owners%20Manual.pdf

There is onboard EQ switchable for 2380 and 2360 horns , it is on a mini switch on the mother board.

[Dr.db]

Thanks a lot; this was the answer I was searching for! :applaud:


So it´s called pre-emphasis and simply is a gain for the frequencies between 500-1000hz to compensate the natural roll-off of the 2380-horn. Without this EQ switched on, the 2380 would be about -10db down at 500hz...
So I should either use the EQ when crossover is at 500hz or instead I could crossover at ~800hz without the EQ...

Does the powerhandling actually decrease a lot when EQ is switched on and lots more energy is driven below 1000hz?

[grumpy]

It would help to read down a section in the manual. The 500-1000Hz nudge for the 2380 series will
indeed introduce a small "effective" power handling reduction in that range, but it's the higher frequencies that are being necessarily EQ'd to compensate for the constant directivity horn type.

Why did I quote "effective"? The power handling of the driver doesn't change. You've just changed the energy in that bandwidth relative to the rest, so for a given position on you're volume knob, the driver will see more
energy in that range. In a home setting, I think most would be leaving the room with their ears bleeding
before this was a problem to be concerned with.

-old Ratbag

[Dr.db]

....but it's the higher frequencies that are being necessarily EQ'd to compensate for the constant directivity horn type.




Hey Grumpy,

thanks a lot for quoting this out!

Please tell me, if I read this manual correct;
Pre-emphasis for the 80-Series horns:
- Boosting the 500-1000hz range
- Decreasing -4db at 2khz
- Increasing +6db at 20khz


So the 2380 with 2445 driver tends to have a peak at 2khz, which I should decrease.
But do I need the 6db increase at 20khz, as I have an additional 2405 slot-tweeter ?




Have a great weekend,
Olaf

[grumpy]

This is more of a EQ trend that starts low at 2kHz and then rises gradually to a boost at 20kHz.

You shouldn't have to make further large adjustments... That is what the compensation EQ is for. You might want to do your own minor adjustments with an eq unit external to the m533.

It does seem like there was a thread about changes to the m553 to better accommodate crossing over to a 2405 (think that was what Mac was getting at), but a passive crossover might be more DIY friendly.