Which Sub Location Do You Like?

**MichiganMan** · **12-22-08, 07:50 PM**

I have a DSP1124P under my tree with my name on it.

But before I play with it I wanted the best non-equalized position for my sub as a starting point. For these two graphs I'm running a single notch filter at 25hz -10db to tame a hump that would otherwise be present. The X-Over is set to 80hz at the processor

What position do you prefer? A or B. I know it can be subjective, I'm just curious what someone else might think.

**salvasol** · **12-22-08, 08:50 PM**

For me ...B position

(that dip on A is larger than the dip on B).

**thewire** · **12-22-08, 09:01 PM**

How did you know it's under the tree did you put it there? Just curious. B looks best and the dip isn't in the 40Hz area so looks good to me.

**imbeaujp** · **12-22-08, 10:17 PM**

Hello, try changing the phase on your sub to see if you have some improvement. If you do not have a phase control, you can change de delay or distance on your receiver. Just 1 foot increment could have an impact.

what will be your crossover frequency ? Are you going to use a Housecurve ? Have you check it with your mains ?

Many questions before using your EQ !

**brucek** · **12-23-08, 10:20 AM**

Yeah, choose A and get rid of the dip at 66Hz with the phase control.........

brucek

**MichiganMan** · **12-23-08, 12:01 PM**

Quote:

thewire wrote:

How did you know it's under the tree did you put it there? Just curious.

Yes

My wife and I pick out most of our presents too each other that way everyone is happy and no returns.

Quote:

imbeaujp wrote:

Hello, try changing the phase on your sub to see if you have some improvement. If you do not have a phase control, you can change de delay or distance on your receiver. Just 1 foot increment could have an impact.

I never thought to use the phase control

I'll adjust it at the processor that way I can adjust in discrete increments. Now that will have an impact at the cross over point right? Is there anything to be on the watch for?

Quote:

imbeaujp wrote:

what will be your crossover frequency ? Are you going to use a Housecurve ? Have you check it with your mains ?

I'm crossing over all speakers at 80hz.

I find my self boosting the sub especially with music. A true flat response seems dull. Eventually I'll use a house curve when I get more proficient at this stuff.

I do have sweeps with the mains included. But I thought the general rule of thumb was to position and equalize the sub first then add in the mains and perform some final tweaks.

**brucek** · **12-23-08, 12:57 PM**

Quote:

I never thought to use the phase control I'll adjust it at the processor

Use the subs phase control first. If that's not successful, then use the sub distance control. (remember the phase control only has an effect once the mains are added)

Quote:

But I thought the general rule of thumb was to position and equalize the sub first then add in the mains and perform some final tweaks.

Correct, but you've done all you can with the sub and you have a dip right at the crossover. Add the mains and use the phase control to remove the problem.

brucek

**MichiganMan** · **12-23-08, 02:21 PM**

Quote:

brucek wrote:

(remember the phase control only has an effect once the mains are added)

Got it!

Is there reason to adjust the phase at the sub rather than through the processor (pre-amp)?

**brucek** · **12-23-08, 03:16 PM**

Quote:

Is there reason to adjust the phase at the sub rather than through the processor (pre-amp)?

The result is generally the same. Sometimes it may be easier to adjust the subs phase dial.
I find it easiest to adjust to adjust the subs phase dial in real time by using the RTA feature of REW while watching the computer screen. I can tell you how to set that up if you have trouble...

brucek

**Wayne A. Pflughaupt** · **12-23-08, 06:31 PM**

I vote B. It looks like the readings were taken with the mains off, so there's not much chance that phase or distance controls will take out the 66 Hz depression the A graph has.

Regards,
Wayne

**MichiganMan** · **12-23-08, 08:51 PM**

Is this the expected level of change from a phase adjust of the sub? Pictured is the sub with mains and no filtering.

**Wayne A. Pflughaupt** · **12-23-08, 10:16 PM**

What's the crossover frequency?

Regards,
Wayne

**MichiganMan** · **12-23-08, 11:25 PM**

Wayne,

The crossover is set to 80hz at the processor. The sub crossover is set to max, 150hz I believe. I'm assuming the processor crossover will assert control.

Not to change the subject, but why is 80hz the THX recomended/setting for the crossover point?

Would it not make sense to increase the crossover point so I can benefit from EQ'ing over a larger frequency range with the DSP1124p?

Anthony

**brucek** · **12-24-08, 06:44 AM**

Quote:

Not to change the subject, but why is 80Hz the THX recomended/setting for the crossover point?

Would it not make sense to increase the crossover point so I can benefit from EQ'ing over a larger frequency range with the DSP1124p?

Over 80Hz, the subwoofer become localizable - something you don't want.

Quote:

Is this the expected level of change from a phase adjust of the sub?

A phase control can have anywhere from no effect to a very large effect, and over a fairly wide range.

The phase control is certainly having a effect between 50-60Hz in your graph.

brucek

**imbeaujp** · **12-24-08, 08:31 AM**

I think you have a better result with 20 degree phase alignement in the 40-60 hz range. It is a nice boost without using any EQ !

Could you post the graph (20 degree) alone just to check it again ?

It is not too bad at all, in my system the crossover frequency is set to 60hz. My mains have large woofers, 12 inches, so I prefer to let them go in that area.

**salvasol** · **12-24-08, 12:51 PM**

Quote:

MichiganMan wrote:

The crossover is set to 80hz at the processor. The sub crossover is set to max, 150hz I believe. I'm assuming the processor crossover will assert control.

What speakers are you using??? ...Are you using them as small??? ...Did you try different crossover frequencies???

**MichiganMan** · **12-24-08, 08:36 PM**

The speakers are Paradigm Studio 100's Servo15 sub. The speakers are set to large. I haven't tried any different crossover frequency yet.

**Wayne A. Pflughaupt** · **12-26-08, 12:56 PM**

Rescale your graphs for 45-105 dB and your response won't look so scary...

Regards,
Wayne

**MichiganMan** · **01-01-09, 09:15 PM**

Wayne,

I did that just so I could see the difference between the two graphs.

At the default scale I could hardly notice a difference.

**Wayne A. Pflughaupt** · **01-01-09, 09:50 PM**

No need to do that - REW has a function that will shift a trace up or down for easier comparison to another traces.

Regards,
Wayne

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