How many db is worth adjusting for ?

[IWC Doppel]

Hi all , I am looking to EQ my subs and wondered how aggressive I should be at EQing a poor response, clearly room related fee is a graph of the worst sub out put and the simulation of the same sub in the same position, I have a 7 db PEQ filter at 34 Hz and a 6 db gain at 25 Hx, but it need a lot more to get flat, is 30db a crazy number to adjust for ? I need a 12+ filter at 34 and a whole heap of gain below 30. HZ ?

Measured

calculated

 

[Wayne A. Pflughaupt]

Is the graph baseline or does it have EQ applied?

BTW, change the graph to logarithmic instead of linear.

Regards,
Wayne

 

[ddude003]

I always wonder what you get when you run off the low end of the frequency response of your speakers/drivers and/or subwoofers... Where and when do you just call it quits in trying to manage that last 5 or 10 hz with eq... Is this the realm of unmanageable distortion chasms???

 

[IWC Doppel]

I do agree in principle that chasing 20 Hz if it looks like the room node is cutting as much as 30 db, I have added 6db gain (not a fan of adding gain) and my processor caps at +6db and I have cut -7db at 34 Hz. I could in theory cut a heap of db from 20 something to the crossover point and just raise the gain on the sub and although I can try to see what it's like it feels like torturing. So wondered what level of adjustment makes the most sense 10db, 20db, more ?

 

[IWC Doppel]

PS I m looking at using the subs between 20-40/50/60 in the system as all the speakers reach reasonably low

 

[Wayne A. Pflughaupt]

I always wonder what you get when you run off the low end of the frequency response of your speakers/drivers and/or subwoofers... Where and when do you just call it quits in trying to manage that last 5 or 10 hz with eq... Is this the realm of unmanageable distortion chasms???

Kind of a moot point with the main speakers, since typically in an HT system they’re high-passed above the point where extension gives up.

That said, running full range it’s usually not a good idea to try to boost the main speakers below their natural extension, as that will cause the woofer to bottom out on loud passages. Naturally lots of factors come into play, such as your volume levels and now robust the speakers are.

With subs, I’ve personally found that trying to EQ deeper extension just doesn’t sound good – the added lows sound unnatural and “loose,” at least with music. IOW, a sub that naturally gets down to 20 Hz is going to sound better than one that was forced to get there from 30 Hz. YMMV.

Regards,
Wayne

 

[ddude003]

If I am reading the specs right your Extremas go down to 35Hz, your Cremona Ms 40Hz and your Electa amatos 42Hz... Do you have some other sub(s) that you don't have listed in your My AV System... Or other trix up your sleeve... Otherwise, I don't see how you can possibly reach down and manage 20Hz to 30Hz... I am not a fan of boosts... Without much more information about your system and room, I would just make a few cuts, -3db or -4db at the most, here and there to tame some hot spots...

 

[Wayne A. Pflughaupt]

I have added 6db gain (not a fan of adding gain) and my processor caps at +6db and I have cut -7db at 34 Hz.

There is no free lunch - any EQ taxes headroom, whether you boost or cut.

The problem is, your sub’s level is typically based on a peak from a room mode: That’s the loudest thing you hear, so that’s what determines the level you initially set.

Cutting the peak will result in the volume being too low. So, you have to turn up the sub. Well – there goes the “headroom” you thought you saved by only cutting.

I could in theory cut a heap of db from 20 something to the crossover point and just raise the gain on the sub and although I can try to see what it's like it feels like torturing.

In reality, that theory will get you the same thing as if you had just boosted 20Hz. You can model the filters in REW and see what happens: You’ll end up with a huge boost at 20 Hz once everything above that point has been depressed.

So wondered what level of adjustment makes the most sense 10db, 20db, more ?

Whether it’s the room, your placement, or the sub itself – according to your graph it’s “done” at ~32 Hz. There is no EQ fix for that. You might be able to get it down to 30 Hz, but it’s doubtful that will make an audible difference.

Regards,
Wayne

 

[IWC Doppel]

Thanks guys, I have been looking more closely at the sub performance on their own and I think I have the phase correct, these results are with two small cut filers at 34 Hz and 68 Hz of only 6 db filters and just the subs, this is the central LP only

I have three subs - Sonus Faber Cremona M's, I believe they should go to 20 or near, they run 12" drivers 400 W amps and weight 75 Lbs each. I dont think I will have a volume shortage if I increase the sub volume they are very low at the moment and then cut more aggressively ?

 

[Wayne A. Pflughaupt]

How big is your room?

Have you tried a corner location, one with uninterrupted wall lengths in both directions?

Regards,
Wayne

 

[IWC Doppel]

The room is quite modest as a UK house in the centre of a City, these are the room dimensions and sub locations, you could argue the room is wider as the two windows to the side are in reveal so another .3m wider for about 30/40% of the room

 

[Wayne A. Pflughaupt]

I'd suggest taking a measurement of one of the subs in a corner and see if it can get down to 20 Hz.

Regards,
Wayne

 

[IWC Doppel]

Good idea, as I will be adding some rears shortly and relocating the surrounds to the sides, so the subs could easily go in / near the corners

 

[ddude003]

All literature I can find online about the Cremona Ms tells me that the Frequency Response is 40 Hz – 30,000 Hz... 91 dB SPL (2,83 V/1m) Sensitivity at 4 ohm Nominal Impedance... Good luck in your leap into the abyss below 40 Hz...

 

[IWC Doppel]

The Cremona M's are Cremona M subwoofers https://www.technologyfactory.eu/data/mediablocks/Sonus_Faber_Cremona_Collection.pdf

 

[ddude003]

Ah, well, my bad... So a "High-pass filter 19 Hz, soft start"... Wonder what their definition of soft start is... Can you take one into your back yard and measure it?

 

[IWC Doppel]

I did think about taking one outside but the cinema room is on the 3rd floor so something like 67 stairs to go down ! Its pretty heavy at 36kg, so I will leave that for the time being !