Protection Caps for 2445/2405

[danvprod]

I am working on a linux-based crossover for my 3-way JBL system (2226/2445/2405). I'm still a bit nervous while I am configuring everything and was contemplating putting a simple series capacitor on the CD and Super Tweeter until everything is nailed down configuration-wise. I wonder, is there a rule-of-thumb for a protection cap? I'd likely want it out of the pass-band, correct?

Plan is to run the 2226 up to about 400-600 Hz (need to do some listening tests). 2445s from 400 Hz - 6-8kHz and the 2405s from 6-8 kHz up.

[grumpy]

Personally, I'd start at the higher end of both ranges you've quoted, and that
assumes a pretty large mid horn. Second, yes, you could shoot for an octave or so
below for the protection cap values... OR you could just make the cap part of
the filter (part active, part passive) which would likely provide more protection,
but means understanding a bit more about the particular driver's behavior
at/near the crossover frequency.

When we did TiDome's 4-way system, I only used such protection on the
tweeter, as the amps used didn't really have much of a pop on startup
(but there was one, so in went the cap).

Main suggestion: power amps on last and off first.

[danvprod]

Thank you! Here is my setup.
2226 in 4.5 cu ft BR enclosure tuned to 40 Hz, 2445 coupled to 250 Hz Tractrix horn and a 2405.
64321
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64325
Here is the linux PC and 8-channel audio interface. The plan is going to be to couple that with a 6-channel amplifier to go to the speakers. I'll have the ability to play back digital files (either directly through MPD on the linux box or via the S/PDIF input of the interface) or play back a line-level source (my turntable through a Decware preamp).

This is upgrading my previous DSP solution, which was a MiniDSP 2x4. Here I had the 2405 on a 12 dB/octave passive crossover and running the mid without a LP filter.

I've contemplated upgrading the MiniDSP to a 4x10 HD, but then I found this tutorial on a Linux-based crossover: http://rtaylor.sites.tru.ca/2013/06/25/digital-crossovereq-with-open-source-software-howto/

I have nearly infinite possibilities for how to configure the crossover in software. I'll plan on doing the cross-over duties, time-alignment, BSC and any other EQ'ing I'll need for the system there in the ecasound chain.

I do also want to explore the idea of phase linearization, which should be possible with this setup as well (MiniDSP would require the FIR-based hardware device, but also possible).

[ivica]

I am working on a linux-based crossover for my 3-way JBL system (2226/2445/2405). I'm still a bit nervous while I am configuring everything and was contemplating putting a simple series capacitor on the CD and Super Tweeter until everything is nailed down configuration-wise. I wonder, is there a rule-of-thumb for a protection cap? I'd likely want it out of the pass-band, correct?

Plan is to run the 2226 up to about 400-600 Hz (need to do some listening tests). 2445s from 400 Hz - 6-8kHz and the 2405s from 6-8 kHz up.

Hi danvprod,


I think over 47 uF cap for VHF driver, and 4.7uF for UHF would not interfere too much to the rest of the networks

Regards
Ivica

[danvprod]

Thank you, this is what I will do.