Hi,
It is designed specifically for music. It has a lower limit of 27Hz or so when properly loaded.
With Tom's expertise I am sure he could have designed a sub if he had wanted to. But I expect it would be a few times larger in volume, 50 or 100cubft instead of 24cubft.
LabHorn is not a sub.
It is designed specifically for music. It has a lower limit of 27Hz or so when properly loaded.
With Tom's expertise I am sure he could have designed a sub if he had wanted to. But I expect it would be a few times larger in volume, 50 or 100cubft instead of 24cubft.
Hmm and I was just browsing the 'lab subwoofer' forum, where it was conceived.
You guys are arguing semantics here. fwiw it's a subwoofer designed for PA applications. (imo of course)
Patrick, I've not found much that models better than a sealed box for ultra low bass. What would you consider for 4 x 15" 'typical' home subs ?
Cheers,
Rob.
You guys are arguing semantics here. fwiw it's a subwoofer designed for PA applications. (imo of course)
Patrick, I've not found much that models better than a sealed box for ultra low bass. What would you consider for 4 x 15" 'typical' home subs ?
Cheers,
Rob.
RobWells said:Hmm and I was just browsing the 'lab subwoofer' forum, where it was conceived.
You guys are arguing semantics here. fwiw it's a subwoofer designed for PA applications. (imo of course)
Patrick, I've not found much that models better than a sealed box for ultra low bass. What would you consider for 4 x 15" 'typical' home subs ?
Cheers,
Rob.
I have a preference for bandpass because it reduces 2nd and 3rd level harmonic distortion. You can get comparable response with a sealed box, certainly - but with more distortion.
Of course the solution to THAT problem is just use a bigger woofer, or one with less distortion.
A good bandpass or acoustic lever is tricky to get right.
Low and behold it's this thread again
Here's a few pictures of others that have gone the Avalanche 18 LLT route. Each one is a seperate, discrete sub - we're at four owners now, soon to be joined by a fifth.
Here's a few pictures of others that have gone the Avalanche 18 LLT route. Each one is a seperate, discrete sub - we're at four owners now, soon to be joined by a fifth.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Patrick Bateman said:
Hi Patrick,
I've modelled my tempests a fair few times (I have 4) in all types of enclosure and I keep going back to sealed. The ported and 6th order BP have a 24dB roll off which also needs a high pass to protect the driver. That pretty much rules them out for the ultra low bass. The 4th order tends to have a 'bump' and then resembles the sealed subs at the lowest frequencies (below the ports output) This was all with an equal box size, which was 600L for 4 drivers.
What would you do ?
I'm space limited as I use 2 labhorns from 20Hz up.
Cheers,
Rob.
phase_accurate said:
This method was described back in 70'th in one of Soviet "Radio" magazine issues. The patent in you link has additional compressor added to gain stages that unfortunately affects equalization, but may be good when used in some kind of disco club when loudness matter more than quality of sound reproduction.
You're saying a 24db rolloff is a bad thing, and I'm saying that it's a good thing. Because the rolloff on the top end is "acoustic", it will filter out distortion.
Imagine two subs, one bandpass and one sealed. They each roll off at 40hz. The sealed one rolls off at 24db per octave via an electronic filter. The bandpass rolls off at 24db per octave via the port's acoustic filtering.
In this hypothetical example, the bandpass sub will have 24db LESS distortion at 80hz, 48db less at 160hz, etc...
A lot of people condemn bandpass because they haven't heard them done well. Done wrong, they sound atrocious.
But done well, their level of distortion is quite remarkable.
Horns and levers share this behaviour as well. Horns are huge, levers aren't well documented. So what does that leave us for low distortion bass?
Bandpass.
Imagine two subs, one bandpass and one sealed. They each roll off at 40hz. The sealed one rolls off at 24db per octave via an electronic filter. The bandpass rolls off at 24db per octave via the port's acoustic filtering.
In this hypothetical example, the bandpass sub will have 24db LESS distortion at 80hz, 48db less at 160hz, etc...
A lot of people condemn bandpass because they haven't heard them done well. Done wrong, they sound atrocious.
But done well, their level of distortion is quite remarkable.
Horns and levers share this behaviour as well. Horns are huge, levers aren't well documented. So what does that leave us for low distortion bass?
Bandpass.
Hi Patrick,
I was talking about the BP's low end roll off, not it's top one. Thats where a highpass needs to be added to the 6th order version to protect the driver below the lower ports cutoff. (and to typical ported box speakers)
I understand what you are saying about the high roll off, and it's distortion reducing properties.
What I was saying is that the sealed box tends to 'win' once you have added the highpass to the BP box. ie it's rolling off at ~12dB/octave in room already (allowing for room gain) and you have to add an electrical high pass to it's already falling slope. ending up with a 24dB / 36dB roll off right at the bottom where you want it to be producing the 'ultra low' stuff.
With sealed you can end up with an almost flat response at the lowest frequencies as the 12dB roll off is compensated by room gain pretty well. With my tempests in 220L enclosures they measured flat from 30Hz down to ~12Hz. (with no EQ)
I'd imagine a BP tuned to ~8Hz with a high pass in place at the same point, and a bit of EQ could work to give a flat response down to 8Hz then drop like a stone below that. I'd imagine it would also be huge
Cheers,
Rob.
I was talking about the BP's low end roll off, not it's top one. Thats where a highpass needs to be added to the 6th order version to protect the driver below the lower ports cutoff. (and to typical ported box speakers)
I understand what you are saying about the high roll off, and it's distortion reducing properties.
What I was saying is that the sealed box tends to 'win' once you have added the highpass to the BP box. ie it's rolling off at ~12dB/octave in room already (allowing for room gain) and you have to add an electrical high pass to it's already falling slope. ending up with a 24dB / 36dB roll off right at the bottom where you want it to be producing the 'ultra low' stuff.
With sealed you can end up with an almost flat response at the lowest frequencies as the 12dB roll off is compensated by room gain pretty well. With my tempests in 220L enclosures they measured flat from 30Hz down to ~12Hz. (with no EQ)
I'd imagine a BP tuned to ~8Hz with a high pass in place at the same point, and a bit of EQ could work to give a flat response down to 8Hz then drop like a stone below that. I'd imagine it would also be huge
Cheers,
Rob.
RobWells said:
About ten years ago I spent a good month trying to get a 6th order BP to work... I gave up in disgust.
I would say that in general, boxes that utilize both the front and the rear radiation are very VERY hard to get right.
Back then I couldn't measure impedance; I'll bet I could get it correct now, with better tools.
But 6th order BP is a very VERY challenging box. It's no wonder Bose gave up on it, in favor of transmission line.
tlmadsen said:
Holy crap, BagEnd, four 21" inch woofers in one box?!? I don't even wanna know.
When you use eq to 'flatten out' the response, you mess with the phase coherency... If you want that in-the-room presence, eq should be avoided at all costs at every point in the signal chain, making changes in tone through cabinet construction, placement, etc., etc. Thiel Audio has the right idea with 6dB/oct xo slopes. I've owned 5 different models and those things are scary with enough power behind them.
Have you thought about bass shakers? There are some pretty powerful ones out there. They might give more effect at 8Hz than any driver/cabinet system.
Besides, don't forget, if you need at least 40 feet available for a 20Hz wave to develop, you'd need a HUGE room to attempt 8Hz even if you had a speaker that could do it easily, or it'd just never show up. But please don't stop trying! I'll be very interested to see what ya come up with.
Patrick Bateman said:
Hi Patrick,
For a good example of a 6th order BP take a look at Dan Wiggins' suggestion for a pair of tempest drivers
here
When modelled against a pair of tempests in a sealed box of same size, the sealed box wins in max spl below 9Hz.
This is why I always end up back at sealed for the ultra low bass.
Cheers,
Rob.
Attachments
RobWells said:
This takes on a whole 'nother tangent, but I would NEVER use a sub that models flat. When placed in a room, the response will be completely scr3wed up.
I'm surprised Dan offered up that design; he knows all about cabin gain too. It's one of the reasons sealed boxes can sound so good, yet model poorly.
As much as I avoid dual-reflex bandpass, I would definitely use a series tuned bandpass over a parallel bandpass. (If some of you are wondering wtf I'm talking about, take a look at this:
parallel dual reflex bandpass
series dual reflex bandpass
The series tuned dual reflex bandpass has a narrower bandwidth, better impulse response, better transient response and is more forgiving of errors.
To make a long story short, series tuned bandpass ownz parallel bandpass
Cool! can you give me some modelled examples with a tempest driver ? I asked you before what would you do with 4 tempest drivers below ~20Hz but you've given no 'real' example. What modelling program shows the response of a series tuned BP ?
Tell you what, You give me the specs and I'll build it over christmas and measure it.
Cheers,
Rob.
Tell you what, You give me the specs and I'll build it over christmas and measure it.
Cheers,
Rob.
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