SVS PB12-ISD/V - 1st stab at calibration - What next?


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Mar 14, 2004
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Had some fun setting up, but need some help now:lease:

I have attached the usual spreadsheet with my response curve.

All speakers set to small, amp crossover at 80hz, volume for the test tones set at -20db and playing in stereo..

The only adjustments I made during the calibration was to change the phase from 0 through to 90 through to 180 and plotted all 3 on the chart. As you can see not much between 90 and 180, but overall a better response at 90...

What do I need to do now to improve this curve?? I'm absolutley clueless and have only been able to pick up the above from the posts you guys have posted.

Any help will be greatly appreciated........:)


  • 1st calibration.xls
    35 KB · Views: 84
Try a slightly different position. I had significant changes just by moving corners, or by moving the sub along a wall or by next to solid furniture.

If you're getting your plots with a mic + software, this shouldn't be too much of a task for you. If it's a manual job, then that could be a pain in the rear!

After a few comments by other notable members, I plotted the FR of all my speakers hooked up to see how the sub interacted with them. I was suprised that although my sub plot mon its own didn't look pretty, the final result was a lot better than I'd thought it would be. Plot all yours working together, with different crossovers and maybe try your speakers on LARGE if you have full range speakers. I found the overall response in this mode, with the sub taking LFE + MAins, was the best for the test.

In practice the best result is all set to LArge with the Sub on LFE only. The bass sounds sooo controlled, tight and what a thump it gives. MAgic!!

Thanks for your reply......It's a manual job but it's not too difficult, just gets a bit boring.

I have B&W603 s3 floorstanders as my mains, B&WLCR60 s3 centre and Mission 77DS rears.

I will try and set all to large and run the test tones as a 5.1 setup. I will try with the crossover @ 80hz then 100 then 120 to see what results this gives.

How do I set the sub to LFE only?

I will plot this then move the sub to a different position and try again!! Would you suggest changing the phase or leave it at 90 deg?

Sorry for all the questions, but I'm determined to try and get this right after spending my well earned cash on this beast:D
Funny you should mention the phase because when I tried the sub with the mains, the optimum phase changed from about 110 deg to 180. Other phases then produced a number of significant troughs that were not there with the sub on its own.

If you are using a RadioShack meter and can be bothered to get some adapters to hook it up to your PC's soundcard and then PC to the amp, you can use some free software, the Room EQ Wizard.

It works really well apart from a confirmed bug in the export to text of the measured data, but apparently that has been fixed already and just waiting for the next release in a couple of weeks.
Forgot to add about LFE on its own.

When you set your mains to LARGE, you will probably get a "hidden" option in your menu for Subwoofer Mode, in which you can select LFE only or LFE + Mains.

My 604's are terrific with LF. I measured my response to be nice and even between 30 and 120Hz. :)
.... oh and BTW, when you get hooked up to software, a frequency sweep of between 15 and 150Hz takes 2 seconds!! :)
The graph doesn't look right to me ,i would try again because its not putting the correction figures into the graph.

Once again thanks for your advice. I will see what I can do this weekend. The problem is I can't disconnect my PC at the moment so I will need to continue with the manual note taking of SPL's.

I think I know how to get LFE only to the sub, I will try it later.


You are correct, the graphs are displaying the RAW figures not the corrected values for the Radioshack meeter. I will correct it and reattach the new version.
guccismith said:

Once again thanks for your advice.


I've only recently acquired my SVS PB12 via a member of the forum, and I am still "messing about" with levels, placement, crossovers, etc. etc. Nearly there!! I'll be posting my results as soon as the bug in the ROOM EQ Wizard is fixed, or if I feel up to it I may just get screen grabs of the various FR's I got.

Even though it is a S/H unit the guys at SVS (Tom and Ron) still took time out to advise me on placement and setup. They really know the meaning of customer service. You couldn't go too wrong by sending them a layout of your room with sizes and let them suggest placement. It can't hurt!!

One thing became clear for me is that no matter where I placed the sub (and the same "effect was present with the mains to a degree too) the room added about 15db between 26-28 Hz. Suggestions from SVS and other members has meant me buying a BFD - Behringer Feddback Destroyer (Pro model DSP1124). In fact the door bell has just gone and its arrived now. Well, that's my weekend sorted!

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