decoupling a sub?

[foamboy]

Is it necessary or recommended to decouple a sub? I am considering getting the KRK RP10 to use with my Rokit 5G2's.


Thanks for the help.

foamboy

[tINY]

Decouple from what?



-tINY

[Jeffrey Hedback]

In one word, yes.

I'm in a unique position to add insight to this question as I am the primary developer/designer (and patent co-holder) of the Auralex GRAMMA isolation platform. I do not now work for Auralex and have no financial interest at all in product...but, when properly decoupled from the floor be it slab or highly resonate wood floor; you can gain tighter, more accurate fundamental and resulting overtones & more efficient power useage. The degree of benefit is related to many things.

Please keep in mind that location, volume, phase adjustment and possible parametric EQ are all important tools in optimal sub integration.

[foamboy]

Originally Posted by tINY

Decouple from what?



-tINY

Uhhh...the floor.




Jeffrey,thanks for the info. Would you happen to have some links to some pertinent info about placement,phase and the various other "pitfalls" that you mentioned?

My room is nearly cubed (11.9x12.6x9) and I have as much room treatment as the room will hold(auralex and 3 diy traps) and I am really just considering a sub to help me "feel" some of the bass that I can't hear. I was actually considering putting the sub right by my feet under my desk and running it at a low volume just to get a better feel of the low end.

Any adviced is appreciated.

Thanks

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[Glenn Kuras]

We never got this thing to market, but we made a sub stand that brought the sub off the floor 10" (I believe it was 10") and the top floated. Bryan was the brain child behind it and most admit it did make a heck of a difference when I tried it out.
Maybe one of these days we will relook into it.

[bpape]

The idea behind the stand really had 3 things going for it:

- It provided isolation from the floor system

- It provided absorbtion at the source to minimize boundary interactions

- It provided spacing from the boundary (gets it off the floor).

The last one is something that people don't really think about. Many tend to think in 2 dimensions when it comes to speaker/sub positioning.

Even if you have a sub sitting on the floor in the middle of the wall, it's still in a corner - the corner formed by the wall and floor. This still gives a lot of gain and the associated modal excitations.

Getting the sub up off the floor helps even more to minimize boundary issues.

Bryan

[chromatronic]

personally my sub have "decoupling invert pyramid" (i dont know in english lol ) and i have put it on a Auralex gramma... it make much difference, its very importante to decouple speakers and even more a subwoofer as it would resonate do violently with the floor if you dont

[tINY]

What you really need to do is position 1, 2, or 4 subs so that you don't excite your massive room modes. That should help out the bass.

You could even do it with your current monitors if you try some different positions.

A 12'x12" span of floor isn't going to move much. So, it won't re-radiate much sound back into your room (especially if you have a desk and a chair on the floor).



-tINY

[Jeffrey Hedback]

Sure (referring to sub integration tips)...

With one sub you're trying to extend the freq response of your monitoring system without horribly exciting the worst elements of your room: first order axial modes. Given your room dimensions,

Step One, location: come in 1/3 from left wall, and come locate front of sub 1.5' in front of front wall. This should excite all modes a modest amount rather than some modes a great amount...this is desired. With multiple subs, you have many placement options...but that's more than you should ever need to deal with...you just need to be able to "flip" on sub for valid reference.

Step Two,volume: adjust volume with your L & R speakers. Does it sound good in this location? Listen at mix and various location in room realizing you're in a battle of compromise but that's OK.

Now, if you have crossover adjustment: typical 80 Hz crossover is fine, but depending on your monitors, distance between monitors & sub, your room dimensions...etc: you may want to raise or lower the crossover point. What you are listening for is a natural extension to the lowest two octaves. Listen to tracks you're familiar with & play chromatic scale from Low E (bass guitar or keyboard) one octave. If the notes sound even and tight, you're on right track. If you're not happy yet, go back to step one: location, then step two volume. You really don't want to hear (localize) the sub as a single factor...you want to work with your speakers & room.

Sidebar: As Bryan will attest the "home" guys have the studio side licked as far as sub integration, expectation and results. Many of the guys don't stop until they've acheived a full-range/hi-res monitoring situation. The home guys will take room sweeps with REW all day & night and compare LF response.

Now if the first three steps are cool: look at phase adjustment...some are fixed 0 or 180, some are continuously variable...what ever yours is...feel free to adjust making sure these are improvements for your room and how you use it...you may improve response at your mix while making client position worse (vice versa...). Take your time and document settings and preferences. Note: you may actually make small adjustments to previous three steps while adjusting phase and that's cool.

Finally, if you have a parametric EQ on sub...go to primary axial mode (see RealTraps mode calc) and make small dip...3 dB or less. You may adjust volume again at this point.

You should now have a fairly well (or very well) integrated 2:1 monitoring set-up.

[Glenn Kuras]

Originally Posted by Jeffrey Hedback

Sure (referring to sub integration tips)...

With one sub you're trying to extend the freq response of your monitoring system without horribly exciting the worst elements of your room: first order axial modes. Given your room dimensions,

Step One, location: come in 1/3 from left wall, and come locate front of sub 1.5' in front of front wall. This should excite all modes a modest amount rather than some modes a great amount...this is desired. With multiple subs, you have many placement options...but that's more than you should ever need to deal with...you just need to be able to "flip" on sub for valid reference.

Step Two,volume: adjust volume with your L & R speakers. Does it sound good in this location? Listen at mix and various location in room realizing you're in a battle of compromise but that's OK.

Now, if you have crossover adjustment: typical 80 Hz crossover is fine, but depending on your monitors, distance between monitors & sub, your room dimensions...etc: you may want to raise or lower the crossover point. What you are listening for is a natural extension to the lowest two octaves. Listen to tracks you're familiar with & play chromatic scale from Low E (bass guitar or keyboard) one octave. If the notes sound even and tight, you're on right track. If you're not happy yet, go back to step one: location, then step two volume. You really don't want to hear (localize) the sub as a single factor...you want to work with your speakers & room.

Sidebar: As Bryan will attest the "home" guys have the studio side licked as far as sub integration, expectation and results. Many of the guys don't stop until they've acheived a full-range/hi-res monitoring situation. The home guys will take room sweeps with REW all day & night and compare LF response.

Now if the first three steps are cool: look at phase adjustment...some are fixed 0 or 180, some are continuously variable...what ever yours is...feel free to adjust making sure these are improvements for your room and how you use it...you may improve response at your mix while making client position worse (vice versa...). Take your time and document settings and preferences. Note: you may actually make small adjustments to previous three steps while adjusting phase and that's cool.

Finally, if you have a parametric EQ on sub...go to primary axial mode (see RealTraps mode calc) and make small dip...3 dB or less. You may adjust volume again at this point.

You should now have a fairly well (or very well) integrated 2:1 monitoring set-up.

Wow great post Jeff. Great to see you around here.
Hey everyone Jeff also did a article for one of our newsletters.
Diffusion is a Wonderful Tool by Jeff Hedback

[foamboy]

Originally Posted by Glenn Kuras

Wow great post Jeff. Great to see you around here.

Indeed it is a great post and greatly appreciated!!!!! It is a lot of food for thought and I will use these as a starting point.Thanks again!!!!


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