Film-Tech Forum ARCHIVE: How much power for subs and stage speakers ?

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Topic: How much power for subs and stage speakers ?

Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 04-06-2002 10:58 PM

Antonio,

Where did I say the 4642A did not support B6? In fact, I said the 4642A DID support B6 as does the 4641 from the JBL line up...the older original 4645 (no suffix) and the original 4642(no suffix) did not support B6.

B6 is a Thiele-Small classification. There is a word to describe the class that is at the tip of my tongue. You should be able to find more about B6 if you do some research into speaker design and the works of Thiele and Small.

The USA-1310 was not as failure prone as the USA-1300. Running it bridged into 4-Ohms is indeed rated though it will run hot. Bridged into 4-Ohms is the same load to the amplifier as stereo into 2-Ohms. Good luck (I'd recommend pressurizing the rack with a filtered blower (on the bottom).

Steve

------------------
"Old projectionists never die, they just changeover!"

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Paul Mayer
Oh get out of it Melvin, before it pulls you under!

Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000

posted 04-07-2002 03:22 AM

The "B6" comes from 6th order Butterworth tuning. It's one of several alignments (e.g. B4, B5, B6, QB3 (Q means quasi), C4, C5, C6) used in Thiele-Small analysis to describe the performance of a speaker enclosure.

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 04-07-2002 04:04 AM

Steve,

You're right. I was dreaming...

THANKS for your availability. As I said we have 4 4645B without any B6 filter and with a poor EQ (they have a very poor sound ). Tomorrow night I'll check the polarity of the entire system. We were going to have our tech to fix the EQ but now that I know all about B6 tuning I'm goint to talk with my manager to have CX1S installed before new equalization.

It is always a pleasure to talk with you!!

Bye
Antonio

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000

posted 04-16-2002 12:16 PM

Steve,

I explain the B6 filter to my manager. It seems that I've discovered "hot water"...

Seems that noone in Italy knows about the B6 configuration with JBL and Electrovoice subwoofers...

I have a question: 4645B has 97dB sensitivity and 800W pink noise power. The B6 filter give a boost of 5.5dB at 30Hz (+/-). When I'll apply the filter, should the power needs increase?
In other words: the 4645B/C can handle 800W with or without the B6 filter?

I would avoid to blow something...

Bye
Antonio

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