Optimal Gain / Volume setting on 2 x SB13-Plus's - AVS Forum
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post #1 of 6 Old 01-22-2013, 07:43 PM - Thread Starter
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Hi All,
I’ve just recently purchased 2 x SB13-Plus’s run out models from the Australian distributor (Deep HZ Audio) and was wondering how best to set the volume / gain control?

The 2 x SB13-plus will be located in a 3900 cubic feet room (reasonably large) that can be sealed. The connection path is a Rotel RSP-1098 processor (with +/- 10db gain control on sub volume) going to a Velodyne SMS-1 (0-100 volume adjustment) going to the two SB13-plus’s.

Is it best to have the gain/volume on the 2x SB13-plus’s set close to zero and lower the volume on the Rotel and SMS-1, or lower the volume/gain on the SB13-Plus’s and increases it on the SMS-1 or Rotel to calibrate?

If you recommend setting the volume/gain on the 2xSB13-plus’s close to zero, do you recommend 0 or something like -4 or -5?

You can see the room the subs will be located in http://www.stephenmacmillan.com/ht in the gallery section.

Also sorry, i just realised after I posted this that i should have posted in the SVS support thread.

Regards and thanks,
Stephen Macmillan
smacmillan@qvalent.com
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post #2 of 6 Old 01-23-2013, 12:51 PM
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The general thought is that if you get the preamp out close to zero, that's a good thing. Between -3 and +3 is a typical recommendation. Lower preamp out settings help ensure you don't end up clipping at the preamp stage. I think Ed Mullen at SVS prefers under zero on the preamp just to be sure to avoid clipping at the preamp. But generally you want to set them so you can properly calibrate them within the adjustment range available in your preamp.
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post #3 of 6 Old 01-23-2013, 02:37 PM
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I believe on all the Sledge amp subs, Ed has said that the subs (not the pre-amp/AVR0 should be as close to zero as possible, while staying within the adjustment range for your bass management/eq setup. So if your pre/avr has trim settings that go to -12db, you would want to make sure you are not exceeding that. I don't believe the Rotel gear you have has any eq or auto setup capabilities, so you would need to do this with an SPL meter or other measurement tool (REW, Omnimic, etc).

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post #4 of 6 Old 01-23-2013, 03:04 PM
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Quote:
Originally Posted by whmacs View Post

Hi All,
I’ve just recently purchased 2 x SB13-Plus’s run out models from the Australian distributor (Deep HZ Audio) and was wondering how best to set the volume / gain control?

The 2 x SB13-plus will be located in a 3900 cubic feet room (reasonably large) that can be sealed. The connection path is a Rotel RSP-1098 processor (with +/- 10db gain control on sub volume) going to a Velodyne SMS-1 (0-100 volume adjustment) going to the two SB13-plus’s.

Is it best to have the gain/volume on the 2x SB13-plus’s set close to zero and lower the volume on the Rotel and SMS-1, or lower the volume/gain on the SB13-Plus’s and increases it on the SMS-1 or Rotel to calibrate?

If you recommend setting the volume/gain on the 2xSB13-plus’s close to zero, do you recommend 0 or something like -4 or -5?

You can see the room the subs will be located in http://www.stephenmacmillan.com/ht in the gallery section.

Also sorry, i just realised after I posted this that i should have posted in the SVS support thread.

Regards and thanks,
Stephen Macmillan
smacmillan@qvalent.com
Since you have an SMS-1 in your system, that adds another layer to the setup. I wrote a procedure to set the volume controls on all the different devices to get them in the proper range. I quote it below:
Quote:
I have dual Submersives, an SMS-1 and an Onkyp Pro 885 with Audyssey MultEQ XT. Here's how I set things up:

First, I set the SMS-1 to Preset 6, which bypasses the EQ. I set the SMS-1 Volume at 15. Then I set any other setting on Page 2 the way I want them. (I generally shut off the crossover, set the LPF to 5 Hz and 6 dB, Phase to "0", etc.)

Next, I set the subwoofer trim to "0" in the Onkyo Pre/Pro. Then, I turn on the Subwoofer Level Calibration tone, and, using an SPL meter at the primary LP, I set the subwooferss volume control(s) so the SPL meter reads 75.

Next, I run Audyssey 8-position Room Correction. This sets the levels, distances, speaker types and crossovers. I try to adhere closely to the Forum Setup Guide:
http://www.avsforum.com/avs-vb/showt...5#post14456895
When I'm finished, I check the subwoofer trim levels Audyssey set. It's always "0" +/- 3. I also check the crossovers, and I usually need to reset them. I usually raise them, (never lower), where needed.

Then I check the distance Audyssey sets for the subwoofer. It *should* be about 4 ft. longer than the actual measured distance. (This accounts for the "latency" in the SMS-1. It takes a few milliseconds for the SMS-1 to process the signal. Setting the "distance" by ~ 4 ft. longer, delays the *speakers* by that same amount of time, getting them back into time alignment with the subs.

Next, I go to the SMS-1's and change from Preset 6 to Setup. I then use the manual EQ to smooth out any final FR abnormalities at the primary LP. I also check the EQ curve at the other LP's to ensure I haven't made anything worse.

Last, I use the SMS-1 volume control to ensure the device has "unity gain". (The cuts and gains invoked by the EQ bands can change the overall volume level. Using the SMS-1's volume control gets the overall gain back to it's original level, or "unity gain"). To do this, I put the SPL meter back at the primary LP and play the subwoofer calibration tone from the Onkyo. I reset the level of the sub(s) to 75 dB. At the same time, I re-check the levels of all the speakers to ensure they are all at 75 dB.

So, that's how I do it. It may work for you also. Good luck.

It won't all be applicable to you because you don't have Audyssey, but it gives the general sequence to use. Also, gain-match the two subs prior to doing anything else. To do that, set their gains to the *exact* same positions. If you want to be more OCD than that, you can move them to the middle of the room and measure their "nearfield" outputs at the exact same distance from the drivers and set their SPL's to be the exact same.

Good luck.

Craig

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Perfection is not attainable, but if we chase perfection we can catch excellence."

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post #5 of 6 Old 01-24-2013, 06:31 PM - Thread Starter
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Hi Guys,
Thanks for taking the time to help me out and explaining the best calibration process. Also thanks for the procedure Craig, i will give it ago.
I also emailed SVS and Ed responded with the below confirming what you stated above:

Hi Stephen -

I would leave the SMS-1 at unity gain, which (if I recall correctly) is about -15, but check with Velodyne to be sure. All things considered, it's best to run the SB13s at a higher gain setting (i.e., closer to 0 dB) and the Rotel at a lower trim level (i.e., closer to -10).

I would set the Rotel to around -8, the SMS-1 to around -15, and then turn-on both SB13's and increase the gain on each until the combined SPL from both subs is level matched to the speaker channels using test tones from the Rotel and your SPL meter.

Once you've done that, report back with the SB13 gain setting on each sub, and I'll advise you if additional tweaking (which would basically involve reducing the gain level on the SMS-1 and increasing the gain level on the SB13s) would be of any benefit.

Thanks and we're looking forward to your reply!

Ed Mullen, PE
Director - Technology and Customer Relations
SVS


Reards,
Stephen
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post #6 of 6 Old 01-24-2013, 08:29 PM
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So, what's the benefit of running the gain on the subs higher and the pre/pro sub out at -8 compared to running the pre/pro at 0 and the gains on the subs at a lower level? SMS level is at 25. I assumed it was best to try to center the pre/pro sub out at 0 and go from there...When I first started using twin Ultras, they were in a room too small, had the sub out from my pre/pro so low that sometimes it wouldn't turn on the subs. That pre/pro is long gone as well as the addition of the SMS to permanent status in my rack. So spill, inquiring mind wants to know.

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