Film-Tech Forum ARCHIVE: what kind of subwoofer is best?

This is topic what kind of subwoofer is best? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Joe Morris (Member # 1553) on 03-02-2003, 03:50 PM:

I am going to be replacing the subwoofers in my auditoriums, are there any particular subwoofers that would be better to use?

Posted by Antonio Marcheselli (Member # 373) on 03-02-2003, 04:42 PM:

Joe,

Other people will give you better opinions, but in my experience, I found the Electrovoice TL880D subwoofers to be very very good, with high sensitivity and very deep low end.

I believe that JBL's subwoofer are also very good but I never heard them with B6 filter.

However, whatever subwoofer you'll decide to buy, be sure to have enough power both from amp and speaker side.
A inadequate low frequency section will always sounds crap!

Bye
Antonio

Posted by Manny Knowles (Member # 1171) on 03-02-2003, 05:22 PM:

My experience is limited to the JBL 4645 subwoofer, so I am not in a position to express an opinion as to which subwoofer is "best." Still, I don't mind saying that I like the 4645 subs just fine. (I'm using 2 of the 4645 subwoofer systems in each of my theatres.)

Are you replacing the entire subwoofer system or just the transducer(s)? The JBL 4645 uses a single 18" transducer. It is an 8-Ohm speaker. The model # of the transducer is 2242H.

[JBL markets at least 2 other subwoofer systems (in the 4000 line) for cinema applications, offering 2 or 4 transducers. I don't have any experience with those, but I know they are out there.]

Posted by Joe Morris (Member # 1553) on 03-02-2003, 06:16 PM:

I blew the 18" I had in there, as a temporary fix, I stuck a 15" MMats Pro in a car box and wired it up. It's on 8 ohms..and sounds really good with my DTS.

Posted by David Stambaugh (Member # 1102) on 03-02-2003, 07:15 PM:

The Electro-Voice subs used here at Regal Cinema World KICK ASS!!! [thumbsup]

Very deep and well-articulated bass, not crappy 1-note jukebox bass. [Wink]

Didn't Brad choose E-V subs for his screening room?

Posted by John Westlund (Member # 913) on 03-02-2003, 07:28 PM:

Yes, I just checked and on the specs list at the end of the pictures of the Film-Tech screening room it says it has 5 EV T-880 18" dual subwoofers.

Posted by Antonio Marcheselli (Member # 373) on 03-02-2003, 07:58 PM:

Manny

Replacing just the transducer is not a good idea, i believe. Each speaker box is designed for its specific transducer.

Bye
Antonio

Posted by John Westlund (Member # 913) on 03-02-2003, 08:02 PM:

Antonio, I have replaced a single transducer in an dual sub enclosure before with no trouble. If you make sure that you get the same model transducer then all should be fine.

Posted by Phil Hill (Member # 371) on 03-02-2003, 08:30 PM:

My 2 cents on subs:

My all-time favorite has gotta be JBL's 4688's. A solid low-end with a great punch. They were discontinued some years ago after a lawsuit from Bose as it used some of their technology without a license. I put many of those in and always loved them.

Another great one is a "ServoDrive" Bass Tech 7 or some such thing. It used a servo motor mechanically connected to speaker cones in a push-pull fashion. They had a great kick-ass low end, but they used to regularly destroy themselves so I stopped using them. I used a lot of those in mostly simulator rides.

In the "high-end" theatres I used one, two, or 4 of the BGW 2200's. They are really great, but very expensive.

Most theatre applications, I agree the JBL 4642's or the EV 880's are the best solution.

>>> Phil

Posted by Manny Knowles (Member # 1171) on 03-02-2003, 10:36 PM:

Antonio: I never suggested that. I merely asked to clarify Joe's intentions.

Posted by Steve Guttag (Member # 268) on 03-02-2003, 10:55 PM:

The JBL 4688 was certainly an interesting sub...it didn't go real deep, as subs go but what it did it did well.

As for current subs...the EV TL-880D is liked by most. It has real drivers in it (EVX-180s). It isn't the most efficient sub out there but there is often a tradeoff of efficientcy vs. bottom end.

From JBL there are three...the 4645C, 4642A and the 4641. The 4645C is the best of the three and has the best drivers of all listed above. The 2242H driver is a phenominal piece. You can pump 800-watt continious pink noise into it ALL DAY and it won't care. The EV and other drivers would kill themselves under that.

The 4645C with B-6 tuning will do you flat down to 22Hz. If you have sound transfer problems, omitting the B-6 tuning will allow it to smoothly roll off.

The 4642A is one of the best bang for the buck systems out there. It has a pair of 4641A drivers...600-watt each in a cabinet that is more efficient than either the 4645C or the EV TL-880D. The bass is not as smooth as the 4645C but pleases most that have it.

The 4641 is a hybrid....it is the same cabinet as the 4645C but with the driver of the 4642A. Think of it as half of a 4642A for those with just optical SR needs or very small cinemas with digital. Its response is definately not as flat as the 4645C.

My favorite sub for the moment is an appropriate number of JBL 4645C.

Steve

Posted by Antonio Marcheselli (Member # 373) on 03-03-2003, 03:34 AM:

Manny

Sorry, I misunderstood you message!

John,

Of course! I've said it because I know some people that replaced their transducers with another ones of another brand... [Frown]

Steve,

It's not clear to me the sensitivity of TL880/4645C. On EV datasheet TL880 is rated 105dB "half space" where 4645C is rated 97dB "half space".

I didn't know that 4688 were discontinued because they implement BOSE tecnology... I have one in my car box that is waiting to become the central part of my future home theater... [Smile]

Bye
Antonio

Posted by Steve Guttag (Member # 268) on 03-03-2003, 08:11 AM:

Check your specs again...

The TL-880D is only 98dB from 100-800Hz and more importantly it is only 96dB from 50-125Hz (1-watt/1-meter). And it is double-18 sub.

The JBL 4645C is 99dB from 50 - 500Hz (1-watt/1-meter) and is only a single-18. Two 4645C would increase sensitivity by 3dB so a fair comparision of the two will have the JBL 6dB more efficient and able to handle about double the power with similar frequency response.

The JBL equivalent to the TL-880D is the 4642A. It's sensitivity is 101dB (1w/1m) and handles a little more power than the TL-880D.

So, I stand by my original statements.

Steve

Posted by Manny Knowles (Member # 1171) on 03-03-2003, 04:22 PM:

Now I think we need some background information on the B6 technology for this thread.

Is it always needed?
How did it get its name?
What exactly does it do?
Who makes good ones?

...etc...

My understanding is that it is a filter that eliminates subsonic frequencies that can be destructive to a transducer that is incabable of reproducing them. I believe there is also an element of equalization.

I'm a little bit hazy on this last point, but somehow I have the impression that the filter must be compatible with the amplifier. Is that right?

That's the extent of my understanding. We don't use B-6 filters and I'm curious as to whether I'm missing out on anything. As I mentioned, I'm using all JBL 4645, 4645B and 4645C subs.

Posted by Steve Guttag (Member # 268) on 03-03-2003, 06:11 PM:

B-6 is an "alignment." One can design a speaker that follows the B-6 alignment. Thus by applying the appropriate B-6 filter, one extends their frequency response and protects the system from subsonics.

It is kinda like slit-loss for subwoofers...just at the opposite of the frequency spectrum. You design your system so that it has a rolloff that will exactly match the anticipated boost and what you get is a ruler flat response that drops like a rock below the tuning frequency.

One has to check as to which subwoofers are so aligned. The EV TL-880D is.

For JBL..watch out...the 4645B and 4645C are B-6 boxes but the original 4645 is NOT. The 4645 used the 2245H driver that has a very low cut off due to its sloppy suspension...however that also makes it more likely to allow the voice coil to overexcurt and jump out of the airgap in the pole piece. There is also the issue of foam-rot that the 2245H suffers from over time.

The JBL 4642 did not have B-6 alignment (it also didn't have very good bass) but the 4642A is B-6 aligned and has decent bass.

Steve

Posted by Manny Knowles (Member # 1171) on 03-03-2003, 06:16 PM:

Thanks for the info, Steve. [Smile]

I've long since changed out all of the transducers in my 4645's so that they have 2242H inside. Where would they fit into all of this? In other words, is there a significant difference in design (and sound) between the original 4645 box versus the 4645B and 4645C? Doesn't one of these has 3 vents..?

Also, I'd be interested to know your opinion regarding whether it's worth the trouble/expense?

Posted by Antonio Marcheselli (Member # 373) on 03-03-2003, 07:19 PM:

Steve

I do not understand. On one pdf I found your data, on another one I found this:

Which are the correct specs?

Bye
Antonio

Posted by Steve Guttag (Member # 268) on 03-03-2003, 08:58 PM:

From personal experience...the ones I listed for you.

A box and driver MUST be designed with the other in mind...the 2245H was not a bad driver...in fact...few drivers could go lower...the 2242 does not play lower.

Chaning out the 4645 (has 3-vents) with a 4642 will compromise the system's response and does not mean that it will perform like a 4645B or 4645C. The 4645B and C are essentially the same...the exchanged two smaller ports for one larger one.

You might want to read the Speaker Design Cookbook to learn about T-S parameters.

Steve

Posted by Manny Knowles (Member # 1171) on 03-03-2003, 09:35 PM:

Golly! Now I'm glad I took the time to ask. Here's what happened...

I inherited a mess of a situation, with nearly every Left, Right and Sub speaker raided of its transducers. Whoever came in and stole those drivers knew enough to leave the centre channel alone (so that limits the number of suspects considerably, but we won't go there).

Anyway, I got a little bit lucky with the subs because I discovered a stockpile of brand-new 2242H drivers stashed away in a storage area, so that's what I put in all of the empty spaces. The other speakers had to wait while the proper replacements were ordered.

To be perfectly honest, I never knew that the drivers for the different manifestations of the 4645 subs were different. Maybe I'll order the correct replacement drivers if I ever have to replace something again. For now, though, they're working out just fine. A million times better than the empty cabinets! [Wink]

[ 03-04-2003, 10:29 AM: Message edited by: Manny Knowles ]