SVS pb12-ultra

[Hostility]

Hey guys, picked one of these up a few months back, haven't really put it to the test but a few weeks ago, i had my brother over and we were playing a video game, and i didnt realize my onkyo set my sub to +4, and i had the gain set to just under a half, 1 port plug in, filter set to 16hz, and i heard it pop/ maybe bottom out. Now is there a way to get a clipped signal from the onkyo? what would make that pop sound? it didnt seem like it was very loud, but there was a big explosion and it made that pop sound. so i turned it down to 0db and the gain on the sub down a bit. But still wasent overly impressed, i thought it would have gotten louder. Now when i ran audyssey it was just a quick one as im in the middle of trying to sell it to get an anthem. any ideas?

 

[timoteo]

The SVS driver is pretty robust & can take a beating. I know most if not all of their subs have a DSP that keeps the sub within its linear operating mode even at full volume. This protects the driver. Even the older BASH amps have soft clipping that does a similar, yet not as effective, protection.

Since you have 1plug in this tells me that what you heard was most likely port chuffing. It can & most often sounds like a popping sound. This in no way damages the driver but instead is just audible distortion that is annoying. I recommend that you keep all the ports open which will have the sub running in its most efficient operating mode & will prevent any port noise.

You mentioned you were not very impressed. Try the sub with all ports open & make sure you have the sub placed correctly in the room. If the sub is in a bad spot then it won't sound good at all where you set. Look up info in doing the "bass crawl". This will help you locate the best spot to place your sub in your room.

Hope these tips help you!!!

 

[Hostility]

Ahh ok that makes more sense as I was doubting that it was bottomin out or anything like that but I've never heard a port chuff like that before lol. Unfortunately my sub can only be in 1 spot right now I have it about 9" from the back wall, I will try all ports open I had it at 16hz as I wanted to feel some of those lower notes but didn't want to tune to 12hz and loose a lot of top end so I figured a happy medium was 16z. So I will give 30hz a shot. Also do I need more room behind the sub do you think? Also is there a way to get a clipped signal from the reciever? I sit almost right beside the sub is there a difference turning the sub up on the reciever compared to the knob on the sub amp? Thanks

 

[Hostility]

Oops for some reason I had 30hz stuck in my head so I took the plug out and turned the switch to 20hz! Tonight I'm going to watch wolverine and see if I can hear a difference unfortunately I won't be able to play to loud with landlord home upstairs.

 

[Ed Mullen]

If you heard a loud pop/clack, you probably bottomed out the woofer. The sub is more vulnerable to bottoming in the 16 Hz mode with one port plugged.

The 20 Hz mode with all ports open will have the most muscular/powerful presentation on most source material and will be less prone to bottoming.

To help avoid overdriving the subwoofer, be sure to level match the subwoofer with the speakers using auto-set-up or an SPL meter.

 

[Hostility]

I find with auto setup it sets the sub to low or to high again I ran it quick as I'm waiting to switch to arc. But I def need to invest in an spl meter. I like it a bit bad heavy sometimes I'm a bass addict

 

[ratm]

I find with auto setup it sets the sub to low or to high again I ran it quick as I'm waiting to switch to arc. But I def need to invest in an spl meter. I like it a bit bad heavy sometimes I'm a bass addict

I had no idea how out of whack my system was till I invested the $50 bucks for the radio shack digital one. Well worth the investment

 

[Ed Mullen]

I find with auto setup it sets the sub to low or to high again I ran it quick as I'm waiting to switch to arc. But I def need to invest in an spl meter. I like it a bit bad heavy sometimes I'm a bass addict

If you like running the subwoofer channel on the hot side, keep in mind that small dB increases in the AVR sub trim level will result in large stress increases on the subwoofer. Running the sub channel 6 dB hot (not uncommon with bass heads) is literally doubling the acoustic output of the subwoofer for any given volume setting.

So if the PB12U continue to exhibit signs of distress at your preferred overall playback level and sub trim level, then I recommend investing in duals.

 

[Hostility]

i turned it down to any where from -4 to 0db, then use the gain on the svs amp to adjust bass. Again i am in an apartment, but when my landlord isnt home i like to be able to "use" the sub. I have yet to try the 20hz tune loud yet so hopefully sometime this week

 

[timoteo]

You should set the volume knob on the SVS somewhere between 35-50%, then if you set all speakers & sub to 75dB you will be able to turn the master volume up to 0dB without worry. I don't know how you will like the bass, whether it will be too much or not enough to your ears. But this will have you set to industry standards & your SVS should have headroom to spare.

 

[Hostility]

Shouldn't auddysey set that all up? Or do you run te setup and them after adjust it?

 

[Ed Mullen]

Shouldn't auddysey set that all up? Or do you run te setup and them after adjust it?

A certain gain setting on the subwoofer amp is no guarantee it will be calibrated to a certain SPL to match the speaker channels.

Some of the new Audyssey set-ups request that you adjust the gain while the AVR sub calibration tone is running to obtain 75 dB.

If your version of Audyssey lacks this feature, then set the sub gain to between 10 o'clock and 12 o'clock and then run Audyssey. Check the AVR subwoofer channel level after running Audyssey. It should not be near either extreme of the control range (e.g., -12 or +12), and preferably slightly into the negative region.

The AVR sub trim level will be your 'baseline' Audyssey setting. From there you can adjust the sub level up or down depending on the source material and your personal preferences.

Again, small gains over the baseline will result in comparatively large increases in subwoofer SPL: +3 dB over baseline will be 41% more SPL from the subwoofer, and +6 dB over baseline will be 2X more SPL from the subwoofer. So in this case 'less is more' and don't go overboard. Start with +2 over baseline and see if you can live with that. Anything approaching +6 is working the subwoofer really hard and indicates you should be thinking about duals.

 

[timoteo]

True, if your AVR requires you to adjust the volume on sub to get to 75dB then the % recommendation I made wouldn't apply. The 35-50% is equal to 10-12o'clock, same thing. That is if your AVR measures & sets the sub trim itself. Of course this is not in stone but a rule of thumb & a good place to start.

Question: I thought every 3dB is a doubling of power not 6dB?

 

[agarwalro]

Unfortunately my sub can only be in 1 spot right now I have it about 9" from the back wall

It sounds like your sub is placed in a location that puts a room mode null at your main listening position. Also, make sure your Mains and SVS are not out of phase. This will also result in a sharp dip around the crossover frequency.

The only way to know for sure is to take room measurements with an SPL Meter and/or measurement mic.

The Real Traps site provides a simple but laborious way to measure room response via test tones played through a CD player and measurements graphed by hand. REW provides a thorough measurement tool but, it is slightly more involved than the Real Traps CD method. Play with settings and measure response to determine the optional location and settings.

The PB 12 Ultra is a beast! Is meets all my bassholic Dubstep and DnB needs very easily.

SVSound - Animation

 

[Ed Mullen]

True, if your AVR requires you to adjust the volume on sub to get to 75dB then the % recommendation I made wouldn't apply. The 35-50% is equal to 10-12o'clock, same thing. That is if your AVR measures & sets the sub trim itself. Of course this is not in stone but a rule of thumb & a good place to start.

Question: I thought every 3dB is a doubling of power not 6dB?

I wasn't contending your original recommendation (which was fine); rather I was clarifying the part of your recommendation where you said 'set the sub and speakers to 75 dB'. The OP subsequently asked if Audyssey was going to do that - and the answer is yes. Exactly how it accomplishes this depends on which version of Audyssey his AVR has - so I was just giving him both scenarios. None of that controverted your advice; it merely complemented it.

A 3 dB increase is a doubling of power, but it is not a doubling of sound pressure. A 6 dB increase is a quadrupling of power and a doubling of sound pressure.

Many enthusiasts like running the subwoofer channel hotter than the baseline setting, but they often don't have a full appreciation for how much more demanding this is on the subwoofer. Running the sub channel level 6 dB hotter than the Audyssey baseline is literally asking the subwoofer to double its acoustic output for any given master volume setting. This will cause the subwoofer to reach its limits that much sooner, which is what the OP was experiencing.

Some enthusiasts are simply bass heads, and like running the subwoofer channel really hot. There is nothing inherently wrong with that, but it comes with a price - requiring either a more capable subwoofer or duals (or sometimes both).

 

[agarwalro]

i turned it down to any where from +4 [Edit: corrected - to +] to 0db, then use the gain on the svs amp to adjust bass.

Also, if you leave the sub trim at 0 and reduce all the other channels by 4 dB the net effect will be the same as leaving all other trims at the Audessy set level and boosting the sub by 4 dB. The benefit of the former is that the apparant bass boost still exists, without bumping up the sub power requirement. Consequently, it is a safer way to get the desired bass boost. Of course, even with the former channel trim arrangement you could push the master volume to the level where the sub bottoms out.

Before you do anything (especially, purchase more sub), find out if you need more sub or not. Buy or borrow a SPL meter and figure out the problem.

 

[Ed Mullen]

Also, if you leave the sub trim at 0 and reduce all the other channels by 4 dB the net effect will be the same as leaving all other trims at the Audessy set level and boosting the sub by 4 dB. The benefit of the former is that the apparant bass boost still exists, without bumping up the sub power requirement. Consequently, it is a safer way to get the desired bass boost.

This is only true if the Master Volume is left unchanged. If the overall playback level is adjusted such that it is the same in both cases, the load on the subwoofer relative to that of the speakers doesn't change.

Take this hypothetical example:

#1) Audyssey Baseline:

L = +1
C = +4
R = +1
RS = +6
LS = +6
SW = 0

#2) Audyssey Baseline With Speakers Unchanged and Sub Running 4 dB Hot:

L = +1
C = +4
R = +1
RS = +6
LS = +6
SW = +4


#3) Audyssey Baseline With SW Unchanged and Speakers Running 4 dB Cool:

L = -3
C = 0
R = -3
RS = +2
LS = +2
SW = 0

Both #2 and #3 have the subwoofer running 4 dB hot. And the acoustic load on the subwoofer will be identical in both cases, provided the overall playback level is the same in both cases.

Note playback level is not the same as master volume setting. Obviously for any given master volume setting, #2 will have a 4 dB higher playback level than #3 - but that delta holds true for all speakers and the subwoofer.

4 dB hotter is 4 dB hotter - no matter how you cut it.

 

[agarwalro]

This is only true if the Master Volume is left unchanged. If the overall playback level is adjusted such that it is the same in both cases, the load on the subwoofer relative to that of the speakers doesn't change.

Note playback level is not the same as master volume setting. Obviously for any given master volume setting, #2 will have a 4 dB higher playback level than #3 - but that delta holds true for all speakers and the subwoofer.

Also, if you leave the sub trim at 0 and reduce all the other channels by 4 dB the net effect will be the same as leaving all other trims at the Audessy set level and boosting the sub by 4 dB. The benefit of the former is that the apparant bass boost still exists, without bumping up the sub power requirement. Consequently, it is a safer way to get the desired bass boost. Of course, even with the former channel trim arrangement you could push the master volume to the level where the sub bottoms out.

Pretty much what I was trying to say, but you explained it much better.

4 dB hotter is 4 dB hotter - no matter how you cut it.

Yup, it's the same, no question .