Film-Tech Forum ARCHIVE: SW Power limitator

This is topic SW Power limitator in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Antonio Marcheselli (Member # 373) on 09-22-2001, 02:16 PM:

Hello everyone.

Few time ago I heard on this forum about a power limitator for a subwoofer, instead of lower its volume.
I'm trying to build my own subwoofer with one JBL 46cm (2440) and I wish to put it (temporarly) in my theater (600 seats, someone will remember the photo of the other 2440 opened from side to side).
To avoid sure overloading, I wish to install a power limitator that limits the input power to xxx W and maintain it while the current is > of xxx.
Question: is there a device like this? Can I build it by myself? Is is exensive?

Thanks for your help!

Antonio

Posted by Gordon McLeod (Member # 33) on 09-22-2001, 04:53 PM:

Install a compressor/limiter on the input to the amplifier and set ts threshold to the max power you want out of the amp

Posted by Steve Guttag (Member # 268) on 09-23-2001, 12:25 PM:

I hope you aren't going to use a JBL 2440 as a subwoofer...since that is/was a compression HF driver (4" diaphragm with 2" exit) you are bound to be disappointed with it's bass response below 500Hz.

Now the 2240 is a LF driver...probably not best suited for subwoofer duty but it can certainly be used as one. I don't recommend compressors for those that don't know what they are doing since they can have a negative result if the power is effectively held at a high level due to sever compression.

Steve

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"Old projectionists never die, they just changeover!"

Posted by Antonio Marcheselli (Member # 373) on 09-23-2001, 02:59 PM:

Steve,

It is one of the speaker in the 4668 (or 4688, I'm sorry I don't have the specs right now) subwoofer we spoke few times ago. I will build my own subwoofer and I will put it in my new Home Theater room...
I think that it will sounds better than my 80W CANTON active subwoofer...
It will be powered by a Crown MT 2401 (perhaps I will exchange the amplifier with a 1201 or 601, what do you think?)
I think that that speaker will be enough for a 30mq room. I didn't check with dolby formulas yet!

Two questions.
1. Where can I found a compressor/limiter
2. Steve: I'm sorry but I didn't understand very well what do you mean with "I don't recommend compressors for those that don't know what they are doing since they can have a negative result if the power is effectively held at a high level due to sever compression".

Thanks for your help!

Posted by Gordon McLeod (Member # 33) on 09-23-2001, 03:09 PM:

DBX , Yamahaa, Ashley all make compressor/limiters