Software Flaw In New Velodyne Subs?

The software does not limit the response to 40Hz. There is a high-pass filter at 15Hz to protect the driver, but that doesn't limit bass in any meaningful way.

Let me explain a bit. What a low-pass filter does is reduce the output of the sub *above* a certain knee frequency, with a certain slope. So, for a low-pass filter of 40Hz with a 12db per octave slope, that means that frequencies at 40Hz and *below* will be passed at full output, but *above* 40Hz the output will be reduced such that by 80Hz the output is down 12db relative to 40Hz.

A high-pass filter does the converse. A high-pass filter at 40Hz with a 12db per octave slope means that frequencies *above* 40Hz are passed at full output, but frequencies below 40Hz are reduced such that by 20Hz the output is down by 12db relative to 40Hz.

Frankly, I think the person looking to set his low-pass filter to 40Hz is being silly. The advantage of using a Velodyne sub is the sophisticated equalization available to smooth the bass response, and the ability to place the sub for optimum bass response in the bottom four octaves, allowing you to place the mains for best imaging without regard for bass. By limiting the sub to bottom-most octave you'll hardly ever get any advantage from it, unless you use it only for home theater and watch action movies. For music, and depending on the system and room, an 80-120Hz low-pass filter, with proper equalization (meaning cuts) to lop off peaks, makes much more sense. I have Revel Salon 2s and use a 120Hz low-pass filter at 12db/octave. The sub really fills in a suck-out my room causes centered at about 100Hz.

I know that many disagree, but IMHO, Irv got it 100% right. To get the maximum benefit, the sub should be crossed in high enough to address room issues. IME, that usually means somewhere north (often well north, depending on the room) of 70hz.

I have other issues with the Velo software but the low pass range isn't among them. As to the confusion re: low pass filters....

It may be easier to think of them as "high cut" filters, cutting the high frequency end of the sub's output.

I agree with previous posters. I don't know why someone would buy a sub that is good to 15 Hz, and then set its low pass filter to the lower 3 dB cutoff frequency of 15 Hz. That makes no sense. Its like buying an amplifier good for 20 Hz to 20 KHz, then feeding it through a low pass filter at 20 Hz. You are using the product well out of its intended design range.

The implication is that the full range speakers go down to 15 Hz already, so why do you need a sub? If you need reinforcement well below 15 hz, you don't buy a product that is good only to 15 Hz.

I think Velodyne's design criteria are fine. A minimum low pass crossover point within a octave or so of the lower cutoff frequency of 15 Hz is sufficient.

You guys are totally missing the point. The flexibility of high-end Full-range speakers that go down to 17hz is totally useless if in order to use the sub, you have to cross it at 40hz. What if I want my speakers to take it to 30 hz and then let the sub kick in? Can no longer do that with this software. I would much rather listen to the higher-quality of my main speakers than the sub in 2-channel; movies are a different story.

I would never want to set the sub's low-cross at 15hz - that's totally ridiculous. But 25-35hz would not be out of the question, depending upon the music. I am also aware of the many ways the software can balance the room, etc. That's not, and never was my point. The limit of 40hz low pass was my point. I have since figured out a work-around with the help of a Velo senior VP. End of angst. Life is good. :-)