Question regarding bass optimization

[ChicagoLR3]

I currently have the set up in my signature, with a Klipsch SW-112 as the subwoofer. Overall I have been quite pleased with it. However, neither the sub or my AVR has controls for bass frequency. The MCACC on my AVR only goes down to 63 hz, and I have it crossed over at 80hz.

The other day I was playing with test tones and my sound meter and noticed that I seem to have a peak around 50hz and another around mid-30s (these frequencies were much louder than 80-50 and 50-30). Which I assume are the result of my room.

I realize I probably need to move my sub to a more optimal place (currently front wall about 1/5 from corner), but do you guys think I could bring down the 50hz peak by lowering my crossover to 50-60hz (can't recall what the low end is) so that the 63hz eq band is in effect? My towers are more than capable of reaching down that low.

 

[lovinthehd]

Your avr's MCACC probably has more filters, and probably to 31hz IIRC, to utilize, more so than your manual graphic eq feature allows...did you set it up using MCACC first? Hard to tell what you did or found with the spl meter from your description....measurement mic/REW software is a better tool than an spl meter....

 

[ChicagoLR3]

Note I have an older version of MCACC on my VSX-52. For the eq, 63hz is the lowest adjustment. I have run it and for the most part it sounds good. With pink noise generated from the AVR I'm running my sub about 5db hot. Its just when I start listening to tones that the differences emerge. I fully admit my placement probably isn't great, I attached a picture of my setup.

The wall on the right is about 4' from the sub. I do know I need to widen my towers to approximately 10' apart (current 6') to be equidistant between the center and my couch. I was thinking that when I do that I'll try placing the sub between the tower and the console.

The other option is to do a sub crawl, but I need either a much longer cord or the wireless sub transmitter.

 

[WaynePflughaupt]

The best way to smooth out the frequency response of a subwoofer is with a parametric equalizer, inserted in-line between the receiver and sub.

Regards,
Wayne A. Pflughaupt

 

[lovinthehd]

I had a Pioneer with MCACC Advanced also, the graphic eq control of the user isn't the same as MCACC from what I've been able to fathom, pretty sure that MCACC version could do down to 31hz with more filters than available in the manual eq. Later MCACC versions can do better (MCACC Pro I believe its called). You could always try a minidsp 2x4 or similar unit to help out. A longer sub cable is cheap....you do know it only has to reach to your seat, right?

 

[Littlefoott]

I realize I probably need to move my sub to a more optimal place (currently front wall about 1/5 from corner)

looks like a sub crawl is in your future, then tune the avr and sub

monoprice subwoofer cable is cheap

 

[ChicagoLR3]

I can't tune the sub, that's the problem.

 

[lovinthehd]

I can't tune the sub, that's the problem.

Get a minidsp 2x4....

 

[Littlefoott]

your room could easily be causing those peaks and finding and treating the cause without measurements
would be a huge effort
rew would help with room treatments, but other then that the sub crawl is your best bet.

Do the sub crawl then tune
tuning the sub:
the objective is to have MCACC set your subwoofer trim levels(channel levels) just above minimum but not bottomed out
adjust your subwoofer gain dial to achieve this (you may have to run MCACC a few times)

your sub gets all the filters and phase alignment that MCACC allows and takes no excess power from the receiver

Run the subs hot by adding to the subwoofer channel level (do not go above 0db channel level)

tuning this way keeps all the subs power requirements on the more robust subwoofer amp where it should be, and not on the receiver and minimizes the chance of distortion

if you want to eq the sub a minidsp would be required as mentioned above

 

[yepimonfire]

You can't escape the room modes in the low frequencies by using better placement in my experience. Placing the sub towards the middle of the room and away from boundaries will reduce the peak but also cause notches in other frequencies. Your best bet is to place the sub in a corner so all room modes are excited equally and use a 31 band equalizer to reduce the peaks at 50hz and 30hz. Check to see if your avr has a manual eq.

Sometimes it's more than just equalization as well, for example, the biggest and loudest room mode for my room is centered at around 58 hz. My sub is on the front wall almost in a corner and my seating position is near the back wall. My mains have a -3dB response of 63hz, which is becomes 50hz in room. The mains are up on stands at about 40 inches above the floor and almost 3 feet from the back wall. Setting a crossover point to 60hz or 50hz significantly reduces this peak since the mains are pulled away from room boundaries and can't reproduce content below 60hz with as much authority. This also eliminates the notch at 70-80hz. Other options include placing a second sub outside of a corner and crossing the corner loaded sub over under 50hz.

If your mains can handle it, I would suggest trying different crossover points near the room mode and see if that changes the response, you might be surprised how that ugly 50hz peak pushes the -3dB point lower on your mains. An 80hz crossover is on the high side of acceptable in my experience anyways. Technically speaking the sub bass octaves don't even begin until 60hz.

Whatever you do, measurements and fine tuning are necessary. For low frequencies setting a laptop in the seating position and taking measurements with rew using the laptop mic is plenty adequate. Just be sure to disable all enhancements and processing in windows.

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[ChicagoLR3]

If your mains can handle it, I would suggest trying different crossover points near the room mode and see if that changes the response, you might be surprised how that ugly 50hz peak pushes the -3dB point lower on your mains. An 80hz crossover is on the high side of acceptable in my experience anyways. Technically speaking the sub bass octaves don't even begin until 60hz.



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I do have the option of dropping the crossover down to 50-60hz, which my towers can handle easily. While it won't solve all my problems, it might sound better by taking care of that first room mode. Unfortunately, my receiver only has eq adjustment down to 60hz, and I don't have any adjustment on my sub.

I have been looking at outboard passive eqs which would give me some options to work with. Something like the ART Eq-351 or something. A minidsp would be nice, but once you add the mic and all, its rolling on $200 pretty quick.

 

[lovinthehd]

I do have the option of dropping the crossover down to 50-60hz, which my towers can handle easily. While it won't solve all my problems, it might sound better by taking care of that first room mode. Unfortunately, my receiver only has eq adjustment down to 60hz, and I don't have any adjustment on my sub.

I have been looking at outboard passive eqs which would give me some options to work with. Something like the ART Eq-351 or something. A minidsp would be nice, but once you add the mic and all, its rolling on $200 pretty quick.

One thing about a minidsp with measurement mic/software is it is far more versatile than an old graphic equalizer (which is very limited compared to a parametric eq). Helps in more areas than just subs.

 

[yepimonfire]

I do have the option of dropping the crossover down to 50-60hz, which my towers can handle easily. While it won't solve all my problems, it might sound better by taking care of that first room mode. Unfortunately, my receiver only has eq adjustment down to 60hz, and I don't have any adjustment on my sub.

I have been looking at outboard passive eqs which would give me some options to work with. Something like the ART Eq-351 or something. A minidsp would be nice, but once you add the mic and all, its rolling on $200 pretty quick.

A mic isn't 100% necessary if all you're doing is bass. You have an spl meter, if it has an ac output a you need to do is hook it into a laptop

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