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Old 9th October 2012, 06:49 PM   #31
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Quote:
Originally Posted by bentoronto View Post
KaffiMann raises a good point.... in support of Rojoh and DJN and me:

if you want to reproduce a piano well (OK... not really possible, but let's say you want to), somehow having your speakers play to 25 Hz for a once-a-century vibration (which your ears add anyway) is the least of your design purposes.

About DrDyna adding better bass, we all have similar experiences. Lots of non-acoustical reasons, of course. But often it is because the "before" woofer wasn't actually producing the bass we imagined it was. Certainly my experience. TODAY when we say "25 Hz, -6dB" we mean it - not like manufacturer's (or DIYer's) unverified claims of yesteryear.

Ben
Just for the record, I'd actually recommend 25hz as a 0db point. It depends on the design you end up with, but in a lot of the various designs commonly used here on diyaudio apart from IB, Onken and some few closed box solutions, you will experience a nose-dive at f3, making a lot of the sounds below this frequency badly (and hardly noticeably) reproduced. It may end up interfering with the rest of the spectrum in some cases.
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Old 9th October 2012, 09:18 PM   #32
djn is offline djn  United States
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I have moved to a much smaller room and I have a number of fixed issues. My woofer cabs are built (that won't change) I have a pair of Lambda TD15X woofers (that won't change) and my room is 16' x 15' (that won't change). So, that leaves the port length and adding subs if I need to.

I can't think of anything else I have control over now.
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Old 9th October 2012, 09:52 PM   #33
Pano is offline Pano  United States
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Originally Posted by DrDyna View Post
The truth is, in a lot of modern music, electronic in particular, we see tons of information below 35 hz.
I'd put a qualifier on this "in a lot of modern recordings".

I don't mind a true, solid 20~25Hz - but it's mostly just the feel of the concert hall down that low. Nice to have, but the music doesn't live down there. 35 Hz does it for me.
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Old 9th October 2012, 10:10 PM   #34
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One point often ignored is that although there may be low frequency content below 35 or 30 Hz, it is rarely at full level. It's often 10 to 25 dB below the upper bass levels. Multiple 15 inch drivers are not necessary to reproduce this content - in many cases, an optimised 8 inch design will be fine.
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Old 10th October 2012, 11:40 AM   #35
DrDyna is offline DrDyna  United States
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Quote:
Originally Posted by Pano View Post
I'd put a qualifier on this "in a lot of modern recordings".

I don't mind a true, solid 20~25Hz - but it's mostly just the feel of the concert hall down that low. Nice to have, but the music doesn't live down there. 35 Hz does it for me.
I suppose the broader idea I was putting out there, despite musical taste or instruments dictating how low we really should go, to me, a solid kick drum or thumped bass guitar sounds different (and better) to me when played with a pair of subs that go down to ~18-20 hz even though the vast majority of the energy is concentrated much higher than that.

For instance, a single thumb or hammer-on from Victor Wooten using even a tenor tuned bass often sounds like the note leads with a solid "pump of air pressure" that you just can't get from something tuned to 35 hz, even though the lowest open string on the tenor-bass is barely in the 40's.

Victor Wooten AMAZING Solo - Hartke "Norwegian Wood" - YouTube

Meh, maybe it's all in my head.
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Old 10th October 2012, 04:16 PM   #36
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No, not in your head.
A slapped bass string on an electric guitar goes down to near DC.

Below are unprocessed screen shots of a low E and a slapped low E on a Yamaha RBX-260 bass guitar, which uses all passive circuitry like any "old school" bass.

As can easily be seen, though the harmonics of 40 Hz are some 20 dB above the fundamental, when slapped, the "fundamental" is as loud as any harmonic, and goes below what most speaker systems can reproduce by a good margin.
When you hear a "slap" like shown on a system with VLF capability, it sounds vastly different than one that rolls off at 40 Hz.

Art

Edit: I had tuned the low string on the bass to B (31 Hz) not E (40 Hz)as written above. The fundamental E is a bit louder than B.
Attached Images
File Type: png Bass.png (66.7 KB, 70 views)

Last edited by weltersys; 10th October 2012 at 04:20 PM.
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Old 10th October 2012, 04:32 PM   #37
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Thanks Art, that certainly makes a case for tweaking a system down as low as posible.
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Old 11th October 2012, 09:29 PM   #38
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Thanks Art, that certainly makes a case for tweaking a system down as low as posible.
Also a good case for HP filters and limiters on bass players that like to slap strings .

Art
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Old 11th October 2012, 10:15 PM   #39
Pano is offline Pano  United States
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Indeed! There's music, and then there's effects.

Now, if I owned a club playing Dubstep, huge SPLs below 60Hz would be very important to me. So would keeping my subwoofers alive. It all depends on what you are trying to do.
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Old 11th October 2012, 11:17 PM   #40
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I'd read a door slamming goes down to 8hz, but I'm not sure how many db down it is compared to say above 50hz...............

But it is true, tuning a sub to 20hz, 30hz could easily bottom it out. My 4 6.3mm 18's tuned to 27hz needed a little over 100 watts each to skip past xmax (I think, years ago) at 40hz (max excursion frequency).

I've been very happy with 6th order (+6 boost at tuning so -3db instead of -9db there) for 27hz. It is a compromise, but I think the lack of ulta lows really sounds much cleaner, like a subsonic filter. Before the boosted box (high pass that has Q=2 at the tuning frequency), the level just got quieter and quieter below 50hz, but there was some below 20hz. Once the boost box was in, in went flat to just below 30hz (massive massive pressure), but 20hz seemed non existant.

Still, 125db from 27hz (and up) is HUGE, I never lusted to go deeper. 60hz shook everything. Most people really don't know what low stuff is. They would assume that the rumbling was 20hz, I'd go, nope, 50hz, or 27hz. It's all just pressure down there.

Then again, I had an accoustat spectra 11 (electrostat over sealed 10", unknown c4rossover point). That thing (while not loud, like 83db spl 1w/1m, forget 100db because it would crackle) just went really low, it was suprising and satisfying most but not all of the time. Too bad I was into super loud then (10 years ago), they'd be great for me now.

My buddy had to retune his 27hz monsters (6th order boosted) in a club for 40hz. Then he never ran out of excursion. And LOUD !!!!!

I think new thx spec (unsure of db) is -3db at 35hz for say the big Imax in chicago. Some people preferring their IB over the Th50 (tapped horn).

I guess you can't have it all without a serious serious investment.

Norman

Last edited by norman bates; 11th October 2012 at 11:36 PM.
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