My first measure

**sonata31** · **11-10-06, 03:56 AM**

I made my first measure of my sub :

REW_freqgraph_subnofilter.jpg

When I click on Find Peak I get the message :

Largest peak found was 29,6dB
Target Level may bet set incorrectly (too low)

Yet the Target Level = 80.5dB

??

**terry j** · **11-10-06, 05:05 AM**

have a look at the frequency range under the find peaks button. You may have the upper figure too high, eg at ( say) 100 hz you may have a signal at 100 db, but the target curve at that frequency may be at 60 hz, giving you a peak of 40 hz. In all likelihood the upper figure will be something like 200 hz, try setting it to 100 hz or a more appropriate figure,

lots of love

terry

**brucek** · **11-10-06, 06:17 AM**

Quote:

I made my first mesure of my sub :

Is this the sub alone or sub plus mains?

What is the crossover setting for your system?

brucek

**sonata31** · **11-10-06, 06:23 AM**

Quote:

brucek wrote:

Is this the sub alone or sub plus mains?

What is the crossover setting for your system?

brucek

Sub alone

The results of Find Peak depend of the Cutoff parameter ?
What value for Cutoff with this response ?

**brucek** · **11-10-06, 06:59 AM**

Quote:

The results of Find Peak depend of the Cutoff parameter ?

Yes.

You are showing a target cutoff for filter suggestion at 60Hz. Is that the crossover setting on your system, because it looks more like 80Hz as shown in the overlay below where I added a 80Hz line...

Quote:

What value for Cutoff with this response ?

Set it to the crossover value set in your receiver.

REWsubnofilter copy.jpg

brucek

**sonata31** · **11-10-06, 07:12 AM**

My connections are :

Ampli Yam (used like pre-ampli) --> DCX2496 --> DEQ2496 --> Ampli --> Front
|------------------------|------------|--------------------> DEQ2496 --------------> Sub
|------------------------|---------------------------------> DEQ2496 --> Ampli --> Centre
|------------------------|---------------------------------> DEQ2496 --> Ampli --> Surrounds
|--------------------------------------------------------------------------------> Surrounds back

This for use my sub in Hi-Fi (mode stereo pure direct on the Yam)

For the test the DCX is bypassed (no crossover), the DEQ is bypassed (no PEQ) and the ampli of front is turned off

**brucek** · **11-10-06, 07:30 AM**

Turn on the DCX and set it to the crossover value set in your receiver DCX2496.

**sonata31** · **11-10-06, 07:33 AM**

Quote:

brucek wrote:

Turn on the DCX and set it to the crossover value set in your receiver DCX2496.

60Hz or 80Hz ?

**sonata31** · **11-10-06, 07:43 AM**

Cutoff on REW and crossover on DCX = 60

REW_freqgrap_subcutoff60.jpg

Cutoff on REW and crossover on DCX = 80

REW_freqgrap_subcutoff80.jpg

And now ?

**sonata31** · **11-10-06, 07:55 AM**

Crossover on DCX at 24dB instead of 12dB

Cutoff on REW and crossover on DCX = 60

REW_freqgrap_subcutoff60.jpg

Cutoff on REW and crossover on DCX = 80

REW_freqgrap_subcutoff80.jpg

And now ?

**sonata31** · **11-10-06, 08:02 AM**

Cutoff on REW and crossover on DCX = 40

REW_freqgrap_subcutoff40.jpg

**brucek** · **11-10-06, 08:30 AM**

Quote:

60Hz or 80Hz ?

Well, this is something you don't ask for an opinion on. It is really determined (demanded) by the speakers you are using.

If the mains speakers have a -3dB down response to 40Hz (for example), you would set the crossover at an octave above that. So they would have to be extremely capable speakers to choose a crossover below 80Hz. That's the preferred crossover. You'll obviously have less equalization control if anything less is chosen.

Subwoofer crossovers are forced at the upper end, so generally set at a fourth order LP and so -24dB per octave would be suitable. For the mains which enjoy a natural falling off at the lower end, then a second order -12dB per octave would be correct.

The cutoff in REW is always set to match the crossover frequency.

brucek

**JohnM** · **11-10-06, 08:33 AM**

The subwoofer target response on REW is based on a 24dB/octave roll-off, per THX recommendations for bass management, which is why you see a better match between actual and target shapes with the DCX set to 24dB.

**sonata31** · **11-10-06, 08:51 AM**

With cutoff=80Hz, what values for Find Peak ?

**brucek** · **11-10-06, 08:54 AM**

Quote:

With cutoff=80Hz, what values for Find Peak ?

20Hz to 200Hz....

**sonata31** · **11-10-06, 08:55 AM**

Thank You for your responses

**sonata31** · **11-10-06, 09:10 AM**

Test after Find Peak and Optimize PK Gain & Q

REW_freqgrap_subcutoff80_afteroptimize.jpg

Test after transfer the settings in the DCX

REW_freqgrap_subcutoff80_correctedauto.jpg

Is it good ?

How reduce the hole at 30Hz ?

**brucek** · **11-10-06, 09:21 AM**

Quote:

Is it good ?

Oui, très bien....

Quote:

How reduce the hole at 30Hz ?

That's hard. Your best bet is to move the sub around a bit. A corner is preferred...

brucek

**sonata31** · **11-10-06, 09:34 AM**

Quote:

brucek wrote:

Oui, très bien....

Good French

Quote:

That's hard. Your best bet is to move the sub around a bit. A corner is preferred...

brucek

I Can't move my sub, because WAF :

PICT0911_1.JPG

434.jpg

A filter PEQ with 7-8dB is correct ?

**brucek** · **11-10-06, 09:45 AM**

Quote:

I Can't move my sub, because WAF

Definitely swap the sub and main in that corner. The main doesn't like the corner and the sub does.... Your wife will never notice....

Quote:

A filter PEQ with 7-8dB is correct ?

Don't really understand the question?

brucek

**sonata31** · **11-10-06, 09:51 AM**

Quote:

brucek wrote:

Definitely swap the sub and main in that corner. The main doesn't like the corner and the sub does.... Your wife will never notice....

I can't swap the sub and main because the screen

Quote:

Don't really understand the question?

brucek

A filter at 30Hz with a gain=7-8dB ?

**sonata31** · **11-10-06, 10:04 AM**

With a filter at 30Hz, gain=+5dB

REW_freqgrap_subcutoff80_correctedauto2.jpg

**brucek** · **11-10-06, 10:08 AM**

Quote:

With a filter at 30Hz, gain=+5dB

That's as high as I would go... no more than +5dB.

Reduce the area from 40Hz to 80Hz a little bit and you're done.....

brucek

**sonata31** · **11-10-06, 10:29 AM**

Quote:

brucek wrote:

That's as high as I would go... no more than +5dB.

Reduce the area from 40Hz to 80Hz a little bit and you're done.....

brucek

I have already set filters to the DCX !!!

**brucek** · **11-10-06, 10:43 AM**

Quote:

I have already set filters to the DCX !!!

Can you not manually adjust them once they are sent?

Dial down the filter gain in that area a few dB and remeasure...

If you saved the unfiltered .mdat file and the filter .req file, then you can play with the filters manually in REW to see the effect...

brucek

Advertisement