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JBL 2205 [message #49150] Mon, 20 March 2006 11:49 Go to next message
Larry Acklin is currently offline  Larry Acklin
Messages: 54
Registered: May 2009
Baron
I have a couple- I ran the specs throuth Pialign, and I don't understand the results- a 2.1 cu ft bass reflex box with (I think) an enclosure tuning of 60 hz? Am I doing something wrong? To be paired (I hope) with JBL 2445Js on the big JBL butt cheek horns the model number I forget.

Comments?

Larry

Re: JBL 2205 [message #49151 is a reply to message #49150] Mon, 20 March 2006 12:50 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

That's exactly right. It makes an excellent sounding speaker.

When used in a seven π cornerhorn, I tuned lower (40Hz) so that the resulting curve was slightly overdamped. But a 2.1ft3 - 2.5ft3 box tuned to 55-60Hz is just perfect for a JBL 2205, providing flat response down to 60Hz. This works very well for a four π cabinet.


Re: Maybe this is a good time to discuss what is bass [message #49152 is a reply to message #49151] Mon, 20 March 2006 18:45 Go to previous messageGo to next message
Bill Epstein is currently offline  Bill Epstein
Messages: 1088
Registered: May 2009
Location: Smoky Mts. USA
Illuminati (2nd Degree)
I think Larry is surprised, and I know I was to find that bass drivers run flat only to 60 to 100 Hz and then roll off. As you said about the Altec 414, lots of mid bass, little deep bass. The 414 was more than 10 dB down at 40 Hz. But the acoustic bass "E" string at 42 Hz just booms out of the speaker.
Now Stereophile, as always, says full range means output dowjn to 20 Hz. But they never say how much?
So when using WinISD and watching the output plot, how many dB can the driver drop below "flat" and still be a "bass" driver?

Re: Maybe this is a good time to discuss what is bass [message #49153 is a reply to message #49152] Mon, 20 March 2006 21:26 Go to previous messageGo to next message
steve f is currently offline  steve f
Messages: 236
Registered: May 2009
Master
Hi All,

Like Bill, I am amazed at how a good speaker with moderate ( say 40 Hz) measured response can sound so powerful in its bass response playing music. Now I have heard a great full range system recently, the Linkwitz Labs Orion. Really impressive speakers. But with non classical music, and more typical instruments, what is really necessary? I don't feel like I'm missing anything when I listen to jazz or rock music. I believe the Orions were down about 6 Db at 20 Hz. I'm willing to bet nobody feels that a speaker like a Pro 7 Pi is lacking anything in low frequency response. What is going on with our perception of bass? Are we responding to psychoaccoustic influences relative to SPL or what?

Cheers,

Steve

Re: Maybe this is a good time to discuss what is bass [message #49154 is a reply to message #49153] Tue, 21 March 2006 00:38 Go to previous messageGo to next message
Bill Wassilak is currently offline  Bill Wassilak
Messages: 402
Registered: May 2009
Illuminati (1st Degree)
Steve,
60hz is considered the thump range, when you get down to around (50hz) or less than 45hz it sounds good and powerful. But when you get around or below that 38-35hz area and if got the power, and it's not rolling off down there (AKA the SPL flat down to 20hz) it takes on other dimensions, because the building AKA(Home construction stiffness) can come into play then.

Butt cheeks horn - 2344 [message #49155 is a reply to message #49150] Tue, 21 March 2006 05:00 Go to previous messageGo to next message
spkrman57
Messages: 522
Registered: May 2009
Illuminati (1st Degree)
And the 2205 would be great to reach up to 1khz(4430/4435 crossover).

Add a powered sub for extra bottom end.

The bonus for tuning at 60hz is great dynamics that a lower frequency driver will not have as good!

Ron

Re: Maybe this is a good time to discuss what is bass [message #49156 is a reply to message #49154] Tue, 21 March 2006 07:41 Go to previous messageGo to next message
Larry Acklin is currently offline  Larry Acklin
Messages: 54
Registered: May 2009
Baron
I do the PA thing for bands in bars on weekends. My PA rig has a 24 db/octave rolloff at 40hz, and is largely flat from there up. My bass horns are dual folded horns in very large and heavy enclosures, with 2 Eminence Delta 15 in each. I cross over to the mids at about 130 hz. I drive both cabs with 1300 watts each.

I'm carrying about 400 lbs of speaker to reproduce Kick drum, some electric bass notes, and keyboards. Yet, I really feel we need all of the above to make the system sound as powerful as it is.

The thing I have found, is if the system has good extension into the bass, it can SEEM to be loud, but it is not. A good thumpin' kick has the fundamental at 80 Hz, 2nd harmonic at 160. Bump up the 160 and lo and behold, the kick seems much louder.

With CD playback, it is very rare that I see (on the RTA) that we approach 40 hz, much less anything below.

The subharmonic synths (aphex, et al) on the market are actually making the sub-fundamental. The psyco-acoustic processor boxes actually increase the second harmonic to make it appear the fundamental is more powerful.

The key for my rig is to use folded horns on the bass, rather than the dual 18's per side, which produce lots of harmonic distortion relative to the horns.

Loud CLEAN bass is good...

Larry

Re: Maybe this is a good time to discuss what is bass [message #49162 is a reply to message #49156] Tue, 21 March 2006 19:53 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
We discussed this at length earlier on this forum; exactly what constitutes bass and how low in frequency a speaker must go to reproduce the entire orchestra. We never really came to any conclusion and I find that peculiar. If the lowest note on the string bass is 31HZ why do we need a subwoofer? I think you have it right. Not for accuracy of reproduction but to accomplish another end. That of pushing the thump.
There's bass then there's thump. It amazes me that guys who swear they are after absolute accuracy in frequency response and show graphs and charts to prove that will add something onto the speaker that is absolutely innacurate. The Thump machine.
Lot of money in those subs; especially if you add one onto an already existing system. If your speakers are already flat through the normal bass region; what exactly are you accomplishing? EQ; thats what.

Re: Maybe this is a good time to discuss what is bass [message #49163 is a reply to message #49162] Tue, 21 March 2006 20:07 Go to previous messageGo to next message
Bill Epstein is currently offline  Bill Epstein
Messages: 1088
Registered: May 2009
Location: Smoky Mts. USA
Illuminati (2nd Degree)
"The thing I have found, is if the system has good extension into the bass, it can SEEM to be loud, but it is not. A good thumpin' kick has the fundamental at 80 Hz, 2nd harmonic at 160. Bump up the 160 and lo and behold, the kick seems much louder."

What Larry says is a revelation to me in terms of our own listening rooms. We often hear about the humps at or near 150 Hz that need bass traps or EQ. And as I recently discovered, the fundamental is way rolled off. As MB says, it's the "thump" we hear and not the fundamental. So I guess that explains why the system I built down 10 dB or more at 40Hz still has strong but boomy bass.

BTW, I went back to sandbox bases for my speakers just tonight. Bigger bases with more sand (50 lbs each) this time and I removed the fancy brass casters. Cleaner, clearer more detail better imaging; the whole 11 yards. If you have a suspended floor you have to try this. Would be interesting to hear the results on a concrete floor, as well.




Live Bass [message #49164 is a reply to message #49156] Tue, 21 March 2006 23:15 Go to previous messageGo to previous message
Shane is currently offline  Shane
Messages: 1117
Registered: May 2009
Illuminati (3rd Degree)
"Loud CLEAN bass is good... "

This was something we always strived for when playing live. We did our own PA work and gradually figured it out over the years. We had some sort of horn cabinets our bass player made from some plans he got where we were running two 18" Peavey Black Widows in each cabinet with about 1500 watts going to each cab. Whatever he did they were nice and clean.

The comparison of listening to music in the home and listening live in a bar is something I have yet to understand. Does the home system reproduce music accurately? Unless I'm running at very, very loud levels I can't make a fair comparison. I've never played a gig or been to a show where the levels were at where most people listen at on their home setup. Even at the symphony, the levels are fairly loud if your in the right spot. I used to take my gradfather to pipe organ concerts at Century II in Wichita for years and let me tell you that damn thing was loud. When they hit a low not the whole building shook--COOL! Many people talk about this speaker or that speaker having great bass or not enough low bass. Well, unless I turn my amp up to clipping levels with my Pi Towers I'm not even approaching the perceived effect of playing live. The kick drum was more a viceral than anything else. When my brother stood up and came down with both pedals on a double bass we had the people's attention, by making them feel like they were getting "thumped" in the belly. Same with smacking that low bass guitar string.

Don't get me wrong, as the Towers produce nice, low bass at moderate listening levels that I can begin to "feel". At low listening levels, say as background music, the bass is there but you have to really listen for it, it doesn't poke it's head out and announce itself. But I know no one that listens at the levels to produce "live music", except maybe at parties (which my wife says I'm too old for now--she's right as always )

I guess my problem is that I'm accustomed to feeling that low end and well as hearing it, and that's what I associate with low bass.

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