Film-Tech Forum ARCHIVE: JBL Subwoofers, B6 and customer service

This is topic JBL Subwoofers, B6 and customer service in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=007028

Posted by Antonio Marcheselli (Member # 373) on 03-15-2005, 04:20 AM:

Hi everyone.

I would like to share with you my experience with JBL cinema customer service and have your opinion on that.

As many of you know I've asked here many times about B6 and its applications on subwoofers. Steve Guttag, that I respect and I consider a VERY competent person, was the one that explained me what B6 mean and told me that JBL 4645B/C subwoofers are B6 enclosures so that if I want to have to use them correctly I should have to install them with a B6 filter.

Now, if you take a look at the Electrovoice or recent QSC sub's datasheet, you can find on the features the fact that the speakers ARE B6 and all the parameter required for the correct operation (frequency, boost, Q) are reported on the datasheet itself or the user’s manual. On JBL datasheet you can just see two graph, that refers to a general "equalization" but nor in the text nor in the specs you can find anything about "B6" or the filter that has to be applied.

I want to say that I agree with Steve that these graphs are there to say that the speakers are B6 enclosures but, you'll understand, since you cannot apply a 6dB boost at 25Hz on every subwoofer you manage... I’d appreciate a better statement from JBL before apply that boost, don't you agree?

I tried many, many, MANY times to contact JBL from their website, but I had no answers. I tried to contact JBL in Italy but with no results.

Then, a "friend" gave me the direct mail of a technical manager at JBL. I wrote a mail to him, asking what JBL speakers support B6 and if the power declared on the datasheet would change when B6 was applied. He forwarded my mail to his engineer that would be able to reply to me.

After few days I received a mail with an attachment. The attachment was a complete math analysis of B6 speakers. The engineer said me "HOW" to discover if a speaker supports B6 or not.

I reply (kindly) that the attachment was very interesting but that some math concepts were not easy for me and that I just wanted to know which, from all JBL speakers, are B6 enclosures.
Note that I own a set of cinema speakers from JBL. So I was speaking as a customer!

I had a reply after 2 MONTHS. They send again the same attachment and told me that they are not in the position to answer me and that an engineer, a specialist or an installer would be able to answer to my questions.

Now, let's ignore that I'm not able to have this answer from any specialist (Steve was the only one but, as I said, I'd appreciate a word from JBL) both in Italy and in USA, don't you think that a feature like "B6" should be clearly declared from the manufacturer? It's like JBL says "this is the subwoofer. We cannot tell you the maximum power you can feed to it, count the coil winding and calculate it by yourself"!!!

WHY JBL doesn't want to tell me if their subwoofers are B6 capable or not? Please note that I didn't ask them how many subwoofer I should install in this or that room or how many amplifier I should provide to the array (just a note: I asked QSC for similar questions and I ALWAYS had support from them) or, in general, how to design a sound system. I asked IF 4645B subwoofer supports a B6 filter!

I tell the story to some installers friends of mine, they all agree with me that it is a feature of the speaker and that should be provided by the manufacturer.

So I start thinking bad: Perhaps that subwoofer were declared B6 but after some problems JBL cancelled any reference from their datasheet (I'm sorry Steve, a graph does not give enough data since B6 filter are not the same for all speakers) and now they cannot answer to my question?

What do you think?

If I have to consider 4645B/C non-B6 speaker, so they're horrible subwoofers that has the 3dB Roll-off at 35Hz! If they're B6 enclosures, I would like to know exactly from JBL because if I add a 6dB boost to a NON-B6 enclosures I'll destroy the subwoofer array...

I know that there is Showest there right now. If some of you has the chance to know something better from JBL I would appreciate it! Tell to JBL that I'm not the only one waiting for an answer! Many theaters and installer would be glad to have an answer!!!

Thank you!

Bye

Antonio Marcheselli