Have you ever seen 5 hz bass? Any BFD gurus out there?

[Bogie]

Lemme tell you, it's scary...

I picked up a Crown XLS602 amp over the weekend, and I hooked it up to the two Quatro 15s last night. Fired it up, and since I just _had_ to check it out, I put in Blackhawk Down, and played the "Irene" scene. About 12db below where I normally watch...

WHOA! Felt like I was looking at a 3-D movie about subwoofers... These things have 10mm of xmax and I'm pretty sure they were using it all before I hit the mute button...

Now, I can sorta solder, etc., but I've gotta implement some sort of rumble filter for this puppy before my next movie night. I can throw in some cheap big caps, and do a simple first order, but I'm wondering... How low can I cut with my Feedback Destroyer? I figure if I can dial the thing way down, and do a wide cut (or two...), would that have the same basic effect?

I'm probably going to order an active 6th order kit from a fellow in Australia, but that's probably going to take me months to assemble - any ideas for two weeks from now?

[AndrewT]

Hi,
is the problem extra bass depth that was not available before, or could it be a sensitivity mismatch?

[Bogie]

The problem is that my old plate amps had a 2nd order highpass filter that was centered on 20hz... So that by the time things got down to 5hz, they were relatively tame. No highpass = big cones going WAY far back and forth...

[BassAwdyO]

5hz isnt so scary..... you reach Xmax there before the power or output get too crazy. Try 30hz with a 34mm Xmax driver going full tilt 68mm p-p and it gets scary....

[simon5]

This thing is 100$, it's not that versatile, but not bad.
Two settings, 15 Hz and 22 Hz.

http://www.hsustore.com/bassoptimizer.html

I've found nothing cheaper than that on the market yet, it's sad I know.

[Bogie]

It's looking like I'm going to be building one of Rod Elliot's 6th order crossovers.

As for low and loud...

http://www.hometheaterforum.com/htfo...01#post1599301

The stuff _is_ out there... I wonder how many people have killed their subs with stuff like Star Wars or the finger chop in Lord of the Rings...

[paulspencer]

IMO a 6th order slope is not needed and makes GD higher than it needs to be to do the job - try modelling in WinISD and you will most likely see what I mean. Look at GD as well as the excursion curve. 20 hz HP with 2nd order for most typical sub designs is about right IME to keep excursion below tuning lower.

Each situation will be different, however. Sometimes you can put the fc of the rumble filter lower and not sacrifice as much low end. At the fc of the rumble filter you lose ~3db so the actual F3 will go up.

[Bogie]

Yeah, but I couldn't find any 2nd order rumble filters that I could run between 17 and 20hz... Unless I wanna start hunting some _really_ big caps and inductors, and go passive.

The ideal dealie would be something like the Hsu thing...

If they can stick an adjustable lowpass crossover and a 20hz 2nd order highpass in a $120 watt plate amp, along with the amp stuff, you'd think that someone could make something we could use with big amps.

[AndrewT]

Hi,
any active high pass filter could be put in front of your power amp.

If you have the schematic all of them can be calculated to any low frequency you need.

So 15Hz to 20Hz is easily achievable.

Try ESP site for a sallen & Key high pass. Unity gain or Equal Value Resistor and Capacitor S&K will do what you require.