The test of a 'Muscial' Sub.


2019-09-21 4:51 pm
Most of the members on this site are not my peers, nor do we share equal appreciation of music genres. There are many design and technical debates. However, the question, "What do you want your sub to do?" is rarely asked.

Home Theatre subs are generally 'minimum wage'; offer maximum: grunt, growl, rumble, or boom when asked and they'll earn their keep. Even and rock and classical fans don't require too much finesse and precision in the lower frequencies. One note often blends into another.

I was weaned on Jazz / Funk and cut my teeth on UK Garage. These genres differ to many others because the bass is the lead, it's where the tune is. In rock music the bass player is the butt of so many jokes because he's the talentless afterthought in the band - who cares if he misses a few notes?

My favoured genre requires quick, tonal, defined bass. I am blessed to have three home audio systems - some of which are better than others at playing 'quick bass'.

(1) It's not always the sub's fault. (Decay, volume of overtones).

(2) You should WATCH this guy while LISTENING - he's really good!!

Indeed! Being blessed with a Cathedral's low B pipe organ within a short drive as a reference, trying to ~accurately reproduce its 'musicality' requires the highest/widest possible BW 'finesse and clarity'. Ditto for symphony, orchestra except it need only go down to ~27 Hz with all these actually limited by the recording's HF BW.


2019-09-17 12:49 am
Depends on Genre
But most of the smack of kick drum and slap bass is upper harmonics.
Plucked or slapped string especially is more 2nd , 3rd harmonics.

So is 60 to 300 Hz
Quick n Accurate would be mid bass, very nice sealed.

problem is yes the other harmonics that do cross into Sub territory can get blurred
or happening in the crossover area.

But since I also love classical and classic soundtracks can appreciate accurate sub bass.
And likewise as you mentioned Electronic like Garage/ House can use layered kicks.
So you have sharp slaps above 60hz and below. And is very nice to hear on a system that can do it.

Electronic is very strange, intense music. Specially with minimal techno.
Again layered kicks and even some kicks have reversed samples, and even
heavy stereo/delayed reverb on some. Hard to describe. The decay is dreamy
and hypnotizing, can be delayed from left to right on the Decay.
They say stereo is not necessary for a Sub. It is...

Specially if you produce these tracks, bass house basslines can use patches
with all kinds of spreader effects, spreader filters. Need stereo.
To avoid poor sub performance and integration you need :

Minimal group delay,
The ability to align with fronts and integrate properly
The ability to EQ adequately
Low distortion
Low cone weight and mms
High (adequate) BL factor
High power high damping factor amplifier, with excellent low impedance performance
Very rigid cabinet with low resonance

Headroom, headroom, headroom

Its more about avoiding the problems with an assertional driver and ensuring it is as good or better than the rest of the system. I get musicality but for me its more about avoiding the problems that smear the timing of music

But Im struggling to understand the question given you are blessed with three systems and some have 'quick' bass ?
Slight segue but relevant... I recently designed and built a headphone amp with current drive and the bass is so smoooth. The midbass is slightly elevated in the 100Hz area due to the HP's natural impedance peak, but only by about 2dB and it doesn't overshadow the deeper rumbles.

And I had an insight about what that "fast" bass was all about, too. Bass like kick drum rolls doesn't throw off the higher frequencies with IMD, despite all passing through the same full-range headphone drivers.

Being a headphone system, naturally the room is excluded, but earlier experiments with raising the output resistance to woofers showed me that room resonances could be made less prominent and with reduced Q. So that could be one thing to look at.


2012-12-30 5:07 pm
I have subs but don't use them. My woofers work well from 24hz to 300hz. I'll play music produced with intentionally deep loud punchy bass but what I really like is when I hear those unintentional acoustic studio noises that I think "might" have been missed by the engineers. Nora Jones, Feels like Home, has a few. That really adds to the soundstage of what would be a lighter production. Puts a nice energy into the room.
Heavier cones are still not zero cost though.

Low pass filters for subs (and all woofers) should have a shape that doesn't create ringing, and that limits the roll-off rate. Linkwitz-Riley and Bessel types come to mind, or linear phase if you can allow a bit of resonance that is 12 or 24dB down. What it means is that the sub always needs some surplus bandwidth so it still sounds good when other speakers begin to take over.
Interesting about inductance, but looking at the SPL curves the mass reduces volume (SPL) ?

I still feel that low driver mass is desirable, from a sensible engineering perspective ?

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No argument from me, I had to reach ~112 dB/4 ft/channel in room before I reached a point of diminishing returns with my long gone all horn loaded system and why I said you were wrong 'as stated' per the article, which BTW and long story ~short/from dim memory; was only written AFTER Tom Danley had gone to the effort of modding a driver to prove I/we were right on the late/(mostly) great 'basslist' and even after he proved it there was still some (otherwise) extremely knowledgeable, well respected members that still couldn't 'see the forest for the trees' and last I noticed this falsehood is still somewhat prevalent around the net, so you're not only hardly alone, but sadly/frustratingly still? in the majority. :(
I still feel that low driver mass is desirable, from a sensible engineering perspective ?

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One exercise in arithmetic would be to compare the ratio of the cone mass to the combined motor + box mass and work out the amplitude of parasitic dipole vibrations. Double the first, and you have to double the 2nd just to break even.

One bit of knowledge that seems to be missing (though I haven't really looked lately) is room simulation in terms of Q.

It seems to me an 'optimum' 0.707 Qtc is only valid when all of the acoustic energy is absorbed in an open field. But indoors it's a different matter. Especially with servo controlled subs at the extreme, what you may end up with is a very "hard" sound source that adds energy to the room but fails to adapt to back-pressure when resonances occur and in-room SPL spirals.

To minimise room resonance it should really be "room Q" that is tuned, even more so than box Q. But my intuition suggests that optimum results may seem very counter-intuitive to some people: oversized bass boxes with light high sensitivity cones running on current source amplifiers.
Interesting I had a chance to listen to a 24" sub yesterday, whilst I believe the cone mass was perceptible on some familiar films tracks the weight, scale and unflappable ability to very quickly pressurise the room and then disappear was impressive and made me look at my 18" used between 40-5Hz, with a thought about perhaps adding another box, this is used with 3 x 12" subs working from 25-70 Hz and I was pretty happy with its performance (below, I guess I still am). This is close to peak output as I only have meaty but ultimately limited 500W(1,000Wm peak) amps for each sub

The 24" comes with its own integrated 6KW amp.... Not sure how musical it is, but I like my 18" for music

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