Film-Tech Forum ARCHIVE: B6 Filters

This is topic B6 Filters in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Antonio Marcheselli (Member # 373) on 09-08-2004, 04:10 PM:

Hi everyone.

I believe that Steve will have an answer for me! I would like to try the B6 on my 4645B but I can't use the QSC filter or the DCM's one.

I have to buy an external filter.

Steve talked about the RDL some time ago but I have a question. I saw that the B6 filter in the DCM applies a +6dB Boost Q=2 at 25Hz. The RDL ones applies a +5.5dB at 32Hz. Q is not declared.

Who is right?

Finally, the last question. I have Behringer 8024 equalizers (the use is not for cinema) that has parametric equalizers inside. I could make a B6 filter appliyng a +6dB at 25/32Hz With Q=2. Is the 20Hz HP filter really needed?

Thanks for your help

Bye
A

Posted by Nicolas Jalabert (Member # 2258) on 10-29-2004, 12:31 PM:

Hello Antonio,

I got the same problem than you.
Who is right for B6 alignement ????

Qsc filter :+6dB Boost Q=2 at 25Hz. The
RDL : 5.5dB at 32Hz

?
+
Nicolas

Posted by Antonio Marcheselli (Member # 373) on 10-30-2004, 02:47 PM:

I'm trying to contact JBL, they sent me a very interesting math discussion on B6 but what I want to know is which JBL speakers can be used in B6 (I understand that there are also Low frequency speakers, not only subwoofer - QSC DCM offers the ability to add B6 on Front speakers too!) and with what kind of filters.
My communication has been interrupted, I do not know why. If and when I'll have these information I'll post them.

For Steve Guttag:
Do not think that I consider you not reliable for this kind of information. It is just because I would like to show to my managers an official note by JBL... Did you know that you're "famous" in Italy for your statements on B6 filters? [Smile]

Bye
A

Posted by Nicolas Jalabert (Member # 2258) on 10-30-2004, 03:58 PM:

hello Antonio

"QSC DCM offers the ability to add B6 on Front speakers too!" [Confused]

I never read this on front speakers for exemple the 4675c.

A friend has just bought a 4645c and Rdl modul CTX. I have hasten to really measure the frequency of boost. But I do not have an spectrum analyser. Is what Behringer deq2496 can do of truth good measure to the bass frequencies <100 hz ?

+
Nicolas

Posted by Antonio Marcheselli (Member # 373) on 10-31-2004, 02:33 PM:

Nicholas

If QSC add these feature on their DCM I believe that there are some speakers in the world that can be used with it! But how can I say which...

About Behringer: 2496 seems a very good machine, they added many features on RTA the 8024 was too fast on low frequency, 2496 has the "infinite" time setting that should permit a good measure.
I have three 8024 for my future HT, they're good machine but the 2496 has everything, plus 24Bit 96Khz DAC converters...

If you need ONLY the RTA take a PC, a good sound card and a linear microphone to have a good measure. On the net there are many RTA analyzer available. I use SpectraLab, there is TrueRTA very good but I cannot use on my laptop, too slow... [Frown]

Ah, With the 2496 you can replace the RDL since it has both HP filter AND the parametric equalizer.

However tell to your friend that if he has 4645C and RDL he should put the "boost" level at maximum to have the "flattest" responce frequency. But as Steve said with an RTA you can judge if the entire BOOST is needed or not.

Did you heard the 4645C with B6 filter? Can you give me an opinion with and without filter?? I'm very curious. I've two 4645B in my garage ready to use but I have to finish the environment before... [Smile]

Bye
A

Posted by Nicolas Jalabert (Member # 2258) on 11-01-2004, 02:48 AM:

Hello Antonio

I am sorry because one still did not install the 4645c. I am very impatient to listen to it. I know that for the rdl it is necessary to put the boost to the maximum for flat response.
My friend will be obliged to buy a rta because he also bought Bss 336 for biamplifier his frontal speakers. Me I said to him that without that it was impossible to regulate anything.

the solution with a PC for the rta is not simple. I tested but I did not have of good result because of the soundcard its integrated into the motherboard.
A Klark tecknik DN6000 well I would have liked but except budget.

as soon as I would have listened 4645c(2242h), I would give you my impression.I would not miss there. [Razz]

Tchao
Nicolas

Posted by Antonio Marcheselli (Member # 373) on 11-03-2004, 03:00 PM:

Thank you, I'll wait your impressions!

About RTA by PC: I believe that for home use a simple Sound Blaster is enough... I bought an external M-Audio, it is flat */-0.3dB, I tested it with Dolby's PN and it is true.

RTA software are very versatile than hardware ones, IMHO.

Bye
A

Posted by Nicolas Jalabert (Member # 2258) on 11-21-2004, 12:11 PM:

Hello Antonio,

I see now that Jbl send you a math discussion on B6. It's a pdf ? Can you send me for read ? Thanks

I didn't find a document that it's say use a B6 on the 4645c. The pdf of the 4645c are very bad. The curve response seem to make very quickly. [Mad]

+
Nicolas

Posted by Antonio Marcheselli (Member # 373) on 11-21-2004, 04:41 PM:

Nicholas,

I'll send you the documents, I have to found them again... [Smile]

I had no others replies from JBL despite my many emails...

Bye
A

P.S. Pls send me again your e.mail address!

Posted by Nicolas Jalabert (Member # 2258) on 11-21-2004, 06:07 PM:

Hello Antonio,

here my e.mail : trebani@wanadoo.fr

I'm not listen also the 4645c of my friend. I wait I wait I www.....

+
Nicolas