bass frequencies

Cochise · Post by **Cochise** » Mon Apr 11, 2011 4:13 pm

The room is an essential issue indeed. I'd just really have to win the lotto; for a good treatment, but especially to have a dedicated (or almost dedicated) room to treat.

Just had a look at this unusual project... it's called 'the door'...

: theDoor1.jpg (61.49 KiB) Viewed 1875 times

Cochise · Post by **Cochise** » Mon Apr 11, 2011 4:36 pm

I've forgotten... this is the subwoofer

: P1000378.JPG (206.51 KiB) Viewed 1873 times

: HS250.JPG (123.76 KiB) Viewed 1873 times

I didn't get the dedicated amp yet, so no hardware phase nor freq controls...

spacef · Post by **spacef** » Tue Apr 12, 2011 3:40 am

wow, that's massive

Cochise · Post by **Cochise** » Tue Apr 12, 2011 4:19 am

yeah. I'm considering to move it in the TV room

Cochise · Post by **Cochise** » Tue Apr 12, 2011 12:18 pm

I eventually succeeded in fitting the sub on the desk

: P1000382.JPG (121.81 KiB) Viewed 1841 times

I'm testing with external amp.
The sound is really deeper now (I'm filtering around 50 Hz)
One thing I didn't expect is the electrical signal at the sub speaker being almost 180 out of phase with the signal microphoned at B2031 woofer (50-60Hz measurements); the signals instead are almost phase aligned when I put the stock Scope low pass filter in the output chain to the subwoofer.

I'm wondering if I'm messing with bass reflex polarities and/or mic positioning

Cochise · Post by **Cochise** » Tue Apr 12, 2011 12:34 pm

Does anyone use Visual Analyzer for phase measures?
There's a specific feature, but I can't get how it works, at now...

valis · Post by **valis** » Wed Apr 13, 2011 12:52 am

If that LCD is ccfl backlit the current mounting (to a vibrating subwoofer) is going to severely shorten its lifespan. Thought I'd warn you so you can prevent turning it on someday only to find it dark.

Cochise · Post by **Cochise** » Wed Apr 13, 2011 3:50 am

Thx for the info. I might try to put some damping material (a diver wet suit?) under the marble block where the arm is fixed... though those frequencies are hard to damp.
Then other troubles could happen with the other LCD staying in front of the subwoofer, under the visible one...

Cochise · Post by **Cochise** » Wed Apr 13, 2011 10:20 am

Ok. The "deepness" was due to 180 degrees phase difference.
I repeated the test using a single mic alternatively for the two signal lines and a control signal. Then I added an inverter in Modular environment. I had to lower the cutoff to 37 Hz.
...The inverted phase sound at 50 Hz was strangely nice though...

The phase measurements features in Visual Analyzer has got a threshold control I didn't noticed yesterday, and the average has to be set to 1

valis · Post by **valis** » Wed Apr 13, 2011 10:27 am

Is it completely 180 degrees out of phase? Many subs have a rotational control (rather than a switch) that helps you vary the phase...

As for the LCD, damping won't help as the arm is a resonator unfortunately. I know how you feel about LCD clearance issues though, I've still got my rightmost monitor sitting on a cutting board (wooden bread board) that's been sitting on this X-stand for far too long. I've been planning on getting some longer monitor arms (like those made by Ergotron) for far too long...

Cochise · Post by **Cochise** » Wed Apr 13, 2011 10:53 am

The project provide this module

: YSA100.jpg (100.59 KiB) Viewed 1812 times

Now I should prefer a lower cutoff, staying to what I hear, leaving the B2031 unfiltered.

Post by **garyb** » Wed Apr 13, 2011 11:48 am

180 degrees out of phase?
reverse the speaker wire connections.

valis · Post by **valis** » Wed Apr 13, 2011 12:17 pm

Hah! True...then phase align it completely. Red's KickMe v2 makes a nice sin sweep tool with a nice kick at the start to make sure transient response aligns too.

Cochise · Post by **Cochise** » Thu Apr 14, 2011 5:17 pm

Transients?
Bass reflex ain't the best architecture for transients imho...

Cochise · Post by **Cochise** » Fri Apr 15, 2011 11:52 am

Actually it looks like inverting I still get around 45 degrees of phase difference (45@33Hz, -315@40Hz, -323@54Hz, 45@66Hz, 51@80Hz); hi-cut at 48Hz

Post by **garyb** » Fri Apr 15, 2011 5:05 pm

move it to a different location.

valis · Post by **valis** » Sat Apr 16, 2011 2:50 am

Cochise wrote:Transients?
Bass reflex ain't the best architecture for transients imho...

That's not the point though, regardless of the response of the speaker/cabinet imo you want the waveform not only phase aligned in terms of peaks/troughs but also in terms of having the initial attack time-aligned. Ie, it's not too hard to get a 50hz sin wave in 'phase' but still have the kick start 180 degrees out of phase or more. Try doing that when layering things in a sampler and it certainly makes a difference, the same applies to playback imo. So you do this by the phase rotation knob, the wiring, tuning the crossover network response (if you can) and by speaker position. Just my 2 cents...

Cochise · Post by **Cochise** » Sat Apr 16, 2011 8:10 am

garyb wrote:move it to a different location.

I think there's two only options for a different placement in this room.
The first is under the desk

: P1000385.JPG (126.5 KiB) Viewed 1741 times

but I fear resonances between floor and the desk top and back boards

The second option is to chain it anywhere to the ceiling.

valis wrote:That's not the point though, regardless of the response of the speaker/cabinet imo you want the waveform not only phase aligned in terms of peaks/troughs but also in terms of having the initial attack time-aligned. Ie, it's not too hard to get a 50hz sin wave in 'phase' but still have the kick start 180 degrees out of phase or more. Try doing that when layering things in a sampler and it certainly makes a difference, the same applies to playback imo. So you do this by the phase rotation knob, the wiring, tuning the crossover network response (if you can) and by speaker position. Just my 2 cents...

Ok, in this case just I can't figure out how I can check trasient alignment in real time.
Actually though, probably transient alignment doesn't makes a huge difference layering sounds in a sampler if you listen the result hi-cutting at 50Hz...
...or not?
Anyway it sounds like inverting the phase (as the bass reflex design requires...) the subwoofer "kicks" something less. It might be due to an higher volume set to compensate phase cancellation (here I'm talking of the configuration having the red wire connected to the + at the speaker), so when (seldom) there are very low sounds, they are reproduced louder.

Post by **garyb** » Sat Apr 16, 2011 9:24 am

that's why the amp has a control for phase, so you can move it across the room if you have to.

Cochise · Post by **Cochise** » Fri Apr 22, 2011 6:40 am

As you disclosed earlier, I've got peaks/valleys in the freq response if the volume ain't set at low levels; too low for effective EQing/mixing.

I had a look at the link kindly posted by Mehdi and, beside the wall panels, corner blocks acting as basstraps are available.

At now I'm just wondering untill which point the material is fireproof.

At now things look this way (not all the corners, though)

: P1000393.JPG (152.34 KiB) Viewed 1663 times

PlanetZ forums - scopeusers.com

bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies

Re: bass frequencies