New VTF3 Owner: Thrilled, but can hear a loud slapping noise

[harsubs]

Hi all. I got my VTF3 (non turbo) a week or so ago and have been playing around with settings placement etc. I have an Ascend (Sierra+170) speaker set up being fed from an Emotiva LMC/LPA combo.

I tried far field placement (front right corner), but the walls rattled so much that I though my basement might collapse - score one for the VTF3 because I need a new house now! So I moved it behind my futon and it feels much better now :)

I still have annoying resonances of various things in my basement, but I can take care of those gradually. Overall I'm very impressed with the power of the VTF3. I have watched a few movies now and this sub has delivered.

However, I can hear an occasional knock/slap/thud:(

LOTR: FOTR - scene where horses are trotting, not galloping: heard a slap. replayed to make sure that it was the subwoofer.

Finding Nemo - scene where Nemo goes to school for the first time and Marlin is talking to the teachers. Again - a slapping sound.

U571 depth charge scene (first chapter) -

Reducing the volume on the sub a little eliminated the slap in all the above cases.

However, the volume is set to less that 25% and I set the signal from the receiver at 0db (i.e same level as my mains). I have it crossed over at 80Hz in my LMC (tried 60 too). I ran the VTF in MO mode as well as with one port plugged. Plugging one port seemed to eliminate the noise, but I cant' be sure becuase I had reduced the volume as well.

Is this noise the woofer reaching its excursion limits, or something else? I'm suprised that this would happen at such a low volume level (less than a quarter of the max).

I'm probably overlooking something in my settings and would like input on how to go about diagnosing this problem. Thanks.

-harsubs

[gvg45]

Have you calibrated your sub with an SPL meter?

[harsubs]

Have you calibrated your sub with an SPL meter?

Yes I have. They are all calibrated to 75db and I turn up the volume a couple of ticks above this when I play movies, so I'm really listening to them at about 79-80 db.

I got a reply from HSU techsupport yesterday that said
"The VTF-3 MK3 has tremendous gain. Typically you will only need to set it to 1/2 a tick up from zero. You are setting the volume control too high. At a 1/2 tick up from zero, with those scenes, you can already drive the sub into overload."

When I tried this, i.e, half way between min and the first tick, the sub registers about 68 db (even with the gain on the prepro turned up by 10), while the other speakers all read 75 db. Cranking the gain on the VTF to the first tick pulls this to 75db and that's the setting I was using.

Maybe its the nearfield location that is causing the SPL to be off. Because the sub is behind my couch, and the SPL is in front of it, the readings are probably lower than what they would be if the sub was in front.

[benchlegs]

Yes I have. They are all calibrated to 75db and I turn up the volume a couple of ticks above this when I play movies, so I'm really listening to them at about 79-80 db.

I got a reply from HSU techsupport yesterday that said
"The VTF-3 MK3 has tremendous gain. Typically you will only need to set it to 1/2 a tick up from zero. You are setting the volume control too high. At a 1/2 tick up from zero, with those scenes, you can already drive the sub into overload."

When I tried this, i.e, half way between min and the first tick, the sub registers about 68 db (even with the gain on the prepro turned up by 10), while the other speakers all read 75 db. Cranking the gain on the VTF to the first tick pulls this to 75db and that's the setting I was using.

Maybe its the nearfield location that is causing the SPL to be off. Because the sub is behind my couch, and the SPL is in front of it, the readings are probably lower than what they would be if the sub was in front.

Where on scale is your (receiver) sub out setting at?

[amdeutsch]

What brand/model SPL meter are you using? Have you taken into account that it may need a correction factor at lower frequencies? What procedure are you using for calibration? Etc.

[harsubs]

Where on scale is your (receiver) sub out setting at?

Main volume is at 45/100. This gives me about 75 db on all speakers. I can change the gain on each speaker by +/- 10. For the sub, if I turn this up to +9 or +10, I can match the speakers' level of 75 db. This is with the gain on the subwoofer at the first tick (25%)

[harsubs]

What brand/model SPL meter are you using? Have you taken into account that it may need a correction factor at lower frequencies? What procedure are you using for calibration? Etc.

I'm using a RadioShack Digital meter (bought a month ago). No, I haven't taken any correction factors into account.

As far as procedure is concerned, I have a tripod that I placed on my futon and put the meter on it (facing slightly upward). The sub is behind the futon. I crank the volume up to a level that gives me 75 dB on my front speaker (test tones from the Emotiva). Then I cycle through all the speakers trying to match this same level. I can turn the gain up or down by 10 for each channel. For the surrounds, because they are closer, I turn the gain down by 4, to give me the same dB level. The sub without any adjustment reads about 67-68dB using this procedure. I increase the gain on that channel to 9 or 10 to get it to read 75dB.

I increased the height of the tripod so that it was just above the height of the futon and got different settings - the back speakers and sub were now showing higher SPLs. Now, with the gain at the value suggested by HSU techsupport, I can get the level to 75dB. I'll watch the movies again and see if the same problem occurs.

[benchlegs]

Main volume is at 45/100. This gives me about 75 db on all speakers. I can change the gain on each speaker by +/- 10. For the sub, if I turn this up to +9 or +10, I can match the speakers' level of 75 db. This is with the gain on the subwoofer at the first tick (25%)

If your sub out controls go from -10 to +10 you should set your receiver gain somewhere around -5. The adjust your sub gain to get the desired 75db SPL. Setting it low will help lessen distortion. Maybe distortion is the cause fo your slapping sound.

[benchlegs]

Main volume is at 45/100. This gives me about 75 db on all speakers. I can change the gain on each speaker by +/- 10. For the sub, if I turn this up to +9 or +10, I can match the speakers' level of 75 db. This is with the gain on the subwoofer at the first tick (25%)

I'm also thinking if you are in max output mode, you may be bottoming out the driver as output tuning is set around 22hz , but will go down to around 18hz.
If the noise goes away when in max extension mode, it seems like that might be the culprit.

[harsubs]

If your sub out controls go from -10 to +10 you should set your receiver gain somewhere around -5. The adjust your sub gain to get the desired 75db SPL. Setting it low will help lessen distortion. Maybe distortion is the cause fo your slapping sound.

If I set my sub out control to -5 or so, I'll need to bump the sub gain well past the point recommended by the techsupport team. They said that the first tick (9 o'clock) was too high.

[harsubs]

I'm also thinking if you are in max output mode, you may be bottoming out the driver as output tuning is set around 22hz , but will go down to around 18hz.
If the noise goes away when in max extension mode, it seems like that might be the culprit.

This might be worth exploring. I'll test this tonight and see if it makes a difference. My previous testing was confounded by volume adjustment becuase my first instinct was the turn the gain down when I heard that slapping noise.

[lradden]

Somethings not right here, the 3.3 has the same 350 watt amp as the VTF3 MK2 use to have. I had two 3.2 with the same amp and each one had it's knob set at 9:00 with my pre amp at -4. There's a bunch of other peole who had this amp in their 3.2 and set their knob at 9:00.

It sounds like there's something wrong with the sub and not an issue ith YOU setting the gain too high. Just search the links below for 9:00 and you'll see other people with the same amp use 9:00.
http://forum.hsuresearch.com/showpost.php?p=9193&postcount=5
http://forum.hsuresearch.com/showpost.php?p=9193&postcount=6
http://forum.hsuresearch.com/showthread.php?t=2742&highlight=9%3A00
http://forum.hsuresearch.com/showthread.php?t=2086&highlight=9%3A00

[Bill3508]

Yep -5 on your sub out and adjust the sub gain up to calibrate at 75. If you do that everything should be fine. If you are still having problems then it sounds like something is wrong with the sub.

Bill3508

[harsubs]

Somethings not right here, the 3.3 has the same 350 watt amp as the VTF3 MK2 use to have. I had two 3.2 with the same amp and each one had it's knob set at 9:00 with my pre amp at -4. There's a bunch of other peole who had this amp in their 3.2 and set their knob at 9:00.

It sounds like there's something wrong with the sub and not an issue ith YOU setting the gain too high. Just search the links below for 9:00 and you'll see other people with the same amp use 9:00.
http://forum.hsuresearch.com/showpost.php?p=9193&postcount=5
http://forum.hsuresearch.com/showpost.php?p=9193&postcount=6
http://forum.hsuresearch.com/showthread.php?t=2742&highlight=9%3A00
http://forum.hsuresearch.com/showthread.php?t=2086&highlight=9%3A00

Thanks for the info, lradden. Heres' what I found yesterday

With the volume knob on my LMC-1 at 50, I get 82 dB from my fronts. I adjusted all the others to read 82 as well. The VTF3 (gain on the sub at 9 o'clock) barely registers 69-70. I moved the sub to the front of the room, i.e. in front of the SPL meter and it made very little difference. If I take measurements a foot or so away from the VTF3, I get readings of 90dB. At my listening position this is down to 70.

However, at this level, when I play the low frequency tones on the test CD, I get playback levels in excess of 90dB. Of course, I have a door that rattles as well at those low freqs. I have had zero issues with the slapping noise at this setting so far.

[harsubs]

Thanks for the info, lradden. Heres' what I found yesterday

With the volume knob on my LMC-1 at 50, I get 82 dB from my fronts. I adjusted all the others to read 82 as well. The VTF3 (gain on the sub at 9 o'clock) barely registers 69-70. I moved the sub to the front of the room, i.e. in front of the SPL meter and it made very little difference. If I take measurements a foot or so away from the VTF3, I get readings of 90dB. At my listening position this is down to 70.

However, at this level, when I play the low frequency tones on the test CD, I get playback levels in excess of 90dB. Of course, I have a door that rattles as well at those low freqs. I have had zero issues with the slapping noise at this setting so far.


Update: Woofer orientation may have been the problem

When I tried far field, the walls shook so violently that I decided to move it behind my futon. When I moved it back to the front of the room, I placed the woofer out, i.e., not firing into the wall but into the room. THis caused the low SPLs I reported earlier. I rotated it so that it fired into the other wall, and now I get less shaky walls and increased SPLs.

[Liaury]

Just want to make sure your crossover setting on the sub amp is "out" (off).

[harsubs]

Just want to make sure your crossover setting on the sub amp is "out" (off).

Yes, the crossover on the sub is "out".

Watched a few scenes and so far no problems with bottoming out. Also, the bass response seems a little more punchy and less boomy. The drums on Track 5 of the test CD sound outstanding. Thanks to everyone who responded and helped me with this issue. Now, I need a new "rattle-free" basement (my wife thinks the walls are going to cave in one of these days :D )

[harsubs]

Heard the dreaded sound again while watching Master and Commander when the cannon is fired:(

I decided to use AVIA instead of the Emotiva's internal tones to calibrate and it looks like the settings are much lower(meaning I was probably running the sub too hot earlier). The knob on the sub is 3/4 between MIN and 9'oclock and the receiver sub channel gain is at -4. But, the sound levels (using the re-directed bass tracks on AVIA) now match those of the mains. Also did a 200-20 sweep and found that a 60 Hz crossover worked better at not causing dips in sound levels between 80-60 Hz. Haven't watched M&C again - hoping to do that tomorrow, but based purely on the level settings, I don't expect to hear the sub bottoming out again.

On a side note, because of the VTF3, I can pick out bass frequencies by listening to what is rattling in my room (Door at 40, Light fixture at 32 etc;) )

[Lwang]

harsubs, so after the final calibration, how many dB hot were you running originally?

[harsubs]

harsubs, so after the final calibration, how many dB hot were you running originally?

About 5-7 dB by my estimation. Also, the M&C track I was listening to was DTS encoded - I don't know if DTS runs hotter for the LFE than DD or not. I'll report back later this evening after watching the same scene in M&C with my previous volume level.

[harsubs]

About 5-7 dB by my estimation. Also, the M&C track I was listening to was DTS encoded - I don't know if DTS runs hotter for the LFE than DD or not. I'll report back later this evening after watching the same scene in M&C with my previous volume level.

Just watched M&C and no botomming:) . The cannon scene was outstanding - more so than before because the bass did not feel excessive. Rather, it was just right.

Well, color me a happy Hsu camper. However, there's no resting - just more testing! I'm off to watch War of the Worlds:D

[Lwang]

That is why it is so important to calibrate the sub properly. It is very easy to set the level 10-20dB too hot (yours might be even more than 5-7dB) since when one buys a sub, they want the hear the sub, so one could go up 20dB w/o noting extreme bass bloat, especially if the crossover freq is low. With LFEs in movies, it would be just as hard to tell since booms and rumbles has no relation in real life and is not integrated with the rest of channels like a musical track's bass.

[harsubs]

That is why it is so important to calibrate the sub properly. It is very easy to set the level 10-20dB too hot (yours might be even more than 5-7dB) since when one buys a sub, they want the hear the sub, so one could go up 20dB w/o noting extreme bass bloat, especially if the crossover freq is low. With LFEs in movies, it would be just as hard to tell since booms and rumbles has no relation in real life and is not integrated with the rest of channels like a musical track's bass.

Good point Lwang. I just couldn't seem to get the right levels using the internal tones of the Emotiva (was about 10dB too low). Placement also didnt' seem to to help out. The AVIA calib. tones seemed to do the trick. Just finished watching the first few scenes of WOTW and all I can say is WOW! The VTF3 is some beast! Thanks to all who helped me in calibrating this.