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Mojave - Thank you very much for the reply. Very good information. I checked out the website for the sound card you have, which one of the X-Fi Elite cards do you have?

I find myself at an impass regarding my system. I'm not sure which way to go, what I need to buy, etc.... Like I mentioned earlier, I've got the DEQ/DCX, I MAY have enough amps for what I want to do. Not sure, it depends on how the pieces of the chain are assembled.
The DCX manual says you need two units to run a 5.1 rig. I'm not interested in EQing the rears. They'll be more than capable of running full range.
I should probably start my own thread......With everything I've got going on, and changes I want to make with the system, I could easily take this thread off topic which wouldn't be fair.

Bob - :wits-end:
 

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Duplicating 20Hz filters on the BFD will give you boost down to around 10Hz.

I am using 2 identical filters @ 20Hz +8dB 120/60 BFD filters instead of a single +16dB @ 20 Hz. So I get an 8dB boost at the bottom end. (Thanks to ThomasW of the IB Cult for this clever idea)
Not getting how this can be. I modeled response in REW and got an improvement of maybe 1 dB @ 10 Hz with dual 8 dB filters vs. a single 16 dB filter. :scratch:

single filter.JPG

double filter.JPG


Regards,
Wayne
 

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Hi Wayne

I found that a single +16dB boost @ 20Hz didn't have the same effect at all.

Here's an "all measured" of my double boost filters.



This means I'll just have to fire up REW again and graph the result of a +16dB boost @ 20Hz. I cannot tell from my hundreds of saved REW graphs which refers to my manifold, the Galaxy 140 SPL meter and +16dB combined. Most of my graphs relate to the array and RS meters. I went over to double filters while still using the array.

BTW: It was Tom Nousaine's idea to use double (or ganged) filters to move the EQ reach beyond the usual 20Hz limit. So you had better take it up with him. :)
 

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Hmm interesting... I can’t see how it would work any different, as long as the bandwidth of the single was the same as the duals. And if they weren’t you could probably tweak the bandwidth of the single filter to duplicate the duals.

What makes the filter reach so far below 20 Hz is the wide bandwidth setting, not the stacking. For instance, you could get even more boost at 10 Hz, and less of a hump at 20 Hz (as shown in my graphs of the electronic response) by opening up the filter even wider, to 3 or even 4 octaves.

Of course, possible differences in phase changes between using the duals vs. the single could account for some room-measured differences, but that’s a pretty murky issue that’s difficult to predict.

In your case you got what you were after, an overall flatter response curve between 10-40 Hz. :T

Be interested to see your other graph when you have the time to do it. :)

Regards,
Wayne
 

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Hi Wayne

Read it and weep! ;)

No description necessary? But for those who haven't been following this thread:

The purple trace is 2 x +8dB @ 20Hz and the green 1 x +16dB @ 20Hz. Both 120/60 BW. (Maximum width and lowest frequency for BFD filters)

 

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I'm going to suggest that you've made an error in your measurement.

Dividing a filters gain in half and adding a second filter will indeed produce a slightly different response curve, but not enough to worry about since you're not trying to filter out a peak.

It's certainly not a bad idea to divide large filters (although the paired filters shape would not be as good a match to the modal resonance being countered as the single filter). Even Behringer acknowledges that single large attenuation filters can be a concern.

Behringer writes:
When using the Feedback Destroyer as a parametric equalizer (Parametric EQ mode) and applying extreme attenuation values in the low end range of the frequency spectrum (below 50Hz), you should perhaps set several filters to process the same frequency. Depending on the amount of attenuation applied, the use of only one filter may lead to slight distortion, which produces interference in the signal path. This is a natural physical phenomenon which should be avoided. Use for example two filters adjusted to a signal attenuation of about -12dB (with the same frequency and bandwidth). This produces the same effect achieved with one filter set to -24dB.


Below is the REW result of the comparison between the two situations. Very, very close. Nothing like you're showing.


one 16 copy.jpg


brucek
 

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:holycow: Wow. Sure wish someone could explain how that works, especially the fact that the gap between the two is greater at the lower end than it is at the filter’s center frequency. Did you get that at the upper end, too (I'm sure you equalized it out if you did)?

Is the BFD output split to two subs? I wonder if that could make a difference. Doesn't seem like it should, but then again it doesn't seem like this technique should work either!

Regards,
Wayne
 

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I'm going to suggest that you've made an error in your measurement. brucek
I'm not a betting man so I won't take your money.

I have just arrived home and it is far too late to repeat the exercise tonight so it will have to wait for the morning.

If you use a BFD then try it for yourself. Set a modest dual filter boost and take an REW response graph.

Then set one of the pair to "Off" and set the remaining filter to double the boost and repeat the REW sweep.
 

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Sorry. You were actually correct and I was completely wrong. Though not intentionally.

I thought I was comparing two very similar filter sets with one difference: One had 2 x +8dB and the other 1 x +16dB. I was badly mistaken.

I had carefully cancelled one of the dual filters and changed the second boost filter to one of twice the boost. (+16db)

It turned out that the rest of the filters in this particular set weren't nearly as alike as I had remembered. So I was really comparing apples with oranges.

Thankyou for pointing this out. The other filters in a set are at least as important as the boost filters to the final result.

Whether there are any benefits to using dual boost filters I have no idea at this point.

I shall have to make a new set that accurately reflects the first but uses a single +16dB boost instead of 2 x +8dB. Then do some listening tests.



Here are the two sets I used for my original test:

Set 1:

20Hz 120BW +8dB x 2

25Hz 30BW -4

32Hz 60BW -6

40Hz 60 BW -6

Set 2:

20Hz 120 BW +16

32Hz 40BW -5

40Hz 30BW -1

50Hz 30BW -2

63HZ 30BW -1

80Hz 40BW +10

100HZ 30BW -10

125Hz 30BW -2
 

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What I'm looking for is the closest thing to an all in one unit that can provide the following. Simulation of an LT circuit for sealed DIY subs, giving reasonable response down to atleast 15hz and preferably 10hz. Solid EQing and if possible, crossovers, time delay, RTA, etc.

I know that nothing will have all of these features. What should I get?
RANE PE-17
DCX2496
BASSIS
Richterscale3 ?:dunno:

I have no experience with any of these units personally. I need to decide in the next few weeks. Recommendations?
 

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The DCX2496 will give you all except the RTA. For that you can use a computer and the Room EQ Wizard. No RTA can best that.
 

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What I'm looking for is the closest thing to an all in one unit that can provide the following. Simulation of an LT circuit for sealed DIY subs, giving reasonable response down to atleast 15hz and preferably 10hz. Solid EQing and if possible, crossovers, time delay, RTA, etc.

I know that nothing will have all of these features. What should I get?
Something to give some thought to:

http://www.thuneau.com/allocator.htm

Bob
 

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Ilkka

Any chance you could post your setup configuration for your DCX2496? Keep running into issues so would really appreciate it..
 
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