id call em.

http://www.mobileaudiocontrol.com/contact.asp

 

I live in Belgium, that would be an expensive phone call, and my spoken english is terrible.

But I just read the manuals of both devices again and apparently the 4XS has a 'PFM Defeat' function. I guess that means I can disable the 'PFM' (subsonic filter), but still use it as a 3-ways crossover (it would be a bit ridiculous to let it act as an expensive line signal splitter, wouldn't it?), so only the subsonic filter of the EQX is enabled (like it should be).

greetz,
Isabelle

 

This won't answer your question, but I am in the same boat with the 4XS.

The instructions aren't very clear for me either. I love AudioControl, but their units aren't user-friendly or very flexible (at least, on the fly) at all and I definately don't consider myself a novice either.

Anyhow, I had a question about another product of theirs and just emailed them. They responded very quickly and answered my question.

Hope this helps,
-Bio

 

I have also contacted AC via e-mail with good luck.

 

As far as the 4SX, all 5 modules have to be installed or you could short the board. If you want full pass on the PFM then put in a lower module, like a 19htz cut off. You cant hear it anyway but it will still keep the woofer from trying to reproduce it (save those VC's!) Anyway if you drop a matching module in both units then you will simply increase the DB slope of said cut off ( e.g. 19htz) But without all 5 board resistors installed the
4XS will short.

 

Yeah, I've used some AC gear over the years (24XS, Epicenter and 4.1) and didn't care that much for the PFM filter not being defeatable either. I never noticed any low information missing, but just knowing it was there bugged me.

I think using a different value resistor network is the only option, but I don't know what the value would be.

 

I still have the 4XS and EQT's I used to use a long time ago. I made a module that had a cut-off of like 19-20 Hz for the PFM. It's not that hard, just follow the formula .... if you don't have the formula for figuring the resistor value let me know - I still have the info around here somewhere in a folder.

 

Thanks for all the information folks, I have the formula and I discovered the 4XS actually has a defeatable PFM, so my problem isn't solved, it just wasn't there

greetz,
Isabelle

 

Yep from what I remembered the 4XS had a defeatable PFM.

The analog Audiocontrol units are much too limited when experimentation and tuning options are a priority.

Not my cup of tea at all.

When you compare a 4XS to a PXA-H700/701.... it really is laughable at how limited you are with the 4XS.

 

I feel stupid here, but can someone explain a little more what the PFM does exactly?

Thanks :blush:
-Bio

 

PFM is just AudioControl's term for an infrasonic ("subsonic") filter, which is just a HPF to keep the sub from overexcurding.

 

Ah-ha!

Now it makes sense.

Thanks,
-Bio

 

so.... I have the great eqx,, it has a inside switch in the pfm it has to be defeated? or activated? what does it ffects? it only affects only the sub channel or the low pass filter channel?
this is a funny thing I have this eqx installed on my truck with premier prs880 and focal krx3 and I always love how it sounds with the eq in button pressed down (not bypassed) but one day by mistake it was depressed and I realise it sounds more powerfull and clean then I let it play so,,, it need to be pressed down and re equalized again? to achieve that same sound and better ? maybe was my bad eq,s setings and I was cutting too many frecuquencies before?? any advises? im missing something with this eqx bypassed? excuse my english spanish is my native tonge

 

I hate to bring up an old thread but, since my DSP (MS-8) has a subsonic filter controllable from the driver's seat.

I wanted to know if I took the chip completely out and left the socket open, would it totally bypass AudioControl's subsonic filter. Or am I stuck with some type of Subsonic filter from AudioControl.

In case it matters, my AudioControl MVCs use the 18dB - 14 Pin modules and they currently have the factory default 33hz chips installed.


Thank you for the help!

 

I would not remove the PFM filter chip and turn your AC MVC on. However you can buy replacement PFM chips straight from AC from this web page: Crossover PFM Modules - AudioControl

On this past Monday I ordered a 15Hz, 18 dB/Octave PFM chip from AC for $10 plus $6.95 shipping to replace the 33 Hz PFM chip in my Epicenter.