Removing infrasonic filters from Rane AC23 Crossover

[Patrick Koller]

Hi,
I have a Rane AC23 active stereo crossover, that I bought a while ago and now want to use it for a current fullrange build.
There are just two things about it, that I don't like:
The first thing is that the delay circuits are for the low- and mid-outputs. I'd rather like to have delay circuits for the high- and mid-outputs, but i think that can't be changed easily, so I have to live with it.

The second thing, I think, can be changed: I'd like to remove the two fixed infra(sub)-sonic filters (3rd order butterworth filters @ 20hz), because I don't need them for my subs and they just rob me of precious low end extension.

Unfortunately I'm a noob at crossover-building/modifying and I can only guess which parts to remove.

Could someone be so kind to tell me which parts on the board are the infrasonic filters so I can unsolder it without destroying my crossover?

Here are some pics:
https://lh3.googleusercontent.com/7...bfEr2qHgIG0wzTHExnbC_yJDhQemenI=w1224-h943-no

 

[badman]

You'd really need a schematic to do so with any confidence, not to mention, surface mount parts are a pain. I wouldn't worry much about it, it's really not a lot you're giving up, only a very small number of movie effects and extraneous signals (noise) live below 25. The highpass helps prevent rumble, etc.

 

[Patrick Koller]

Isn't this a shematic? (For some reason this picture is just a link in my first post)

An externally hosted image should be here but it was not working when we last tested it.

 

[Lojzek]

Service manual is freely obtainable if you look for it. I agree with badman. Yellow caps 0.33 uF are part of the 3rd order high pass. Use simulation software and measure first, then consider mods, if you know what you are doing.

 

[AllenB]

Isn't this a shematic?

No.

 

[MAAC0]

Rane's old support site gone. They used to have schematics there.

Try here:

Free Rane Diagrams, Schematics, Service Manuals :: Schematics Unlimited

 

[Patrick Koller]

Thanks!
I found a schematics-file, but it's pretty hard to understand for me.
This should be the Input/Subsonic Filter section of channel 2:

I think I should go to a local technician for this mod.

 

[Lojzek]

This is what a BW 3rd order 20Hz cut-off(-3dB) looks like. It does not look that threatening to bass performance, imo.

 

[phase_accurate]

It seems that this one isn't even a Butterworth HP with an f3 around 20 Hz but more like a Tchebycheff with an f3 around 15 Hz.

It should therefore be even less of a threat to bass response - at least in the frequency domain.

Regards

Charles

 

[eriksquires]

I'd like to point out a couple of things.


This sort of project is worthwhile only as a learning exercise. Maybe you are better off learning to make your own from scratch? Op amp filters can be a lot of fun. I bet that after 2-3 weekends of breadboarding an NE5532 based crossover you'd learn what you needed.





Next, you can do all you want in a miniDSP type of crossover.