New review of the VTF-3 MK3 Turbo

[cacihome]

http://www.soundandvisionmag.com/speakers/2316/shootout-five-mid-price-subwoofers-page1.html

Can Peter Marks explain me why they got only 83db at 16hz and 93db at 20Hz while the first review said 112db at 20hz by Howard Festler?

Is it beacuse the room is 7,500 cu feet? DOes the DB drops as much depending on the room.?

This seems unfair to me that the 3.3 gets an evaluation on a room such big, while Velodyne DD-18 and others costing three times more get reviews on 3,400 cu feet "so they could get higher DB readings"?

You know to me they are manipulating the reviews so the subs they want "seem" to get higher SPL readings!!!
I only trust HSU for SUBS and that is my final word, as a proud owner of a 3.3 w turbo.

[bassman]

I believe Festler's numbers.

Read here:
http://www.hometheatershack.com/forums/home-audio-subwoofers/4294-subwoofer-tests-spring-2007-a-6.html#post36244

Add 6db to the numbers to be the equivalent of taking the sound measurement at 1m.

Not only do I believe Ilkka's numbers b/c I respect him alot, but because I am getting well over 110 db in my room :) (http://www.hometheatershack.com/forums/members/ilkka.html)

[JimLely]

http://www.soundandvisionmag.com/speakers/2316/shootout-five-mid-price-subwoofers-page1.html

Can Peter Marks explain me why they got only 83db at 16hz and 93db at 20Hz while the first review said 112db at 20hz by Howard Festler?

Is it beacuse the room is 7,500 cu feet? DOes the DB drops as much depending on the room.?

This seems unfair to me that the 3.3 gets an evaluation on a room such big, while Velodyne DD-18 and others costing three times more get reviews on 3,400 cu feet "so they could get higher DB readings"?

You know to me they are manipulating the reviews so the subs they want "seem" to get higher SPL readings!!!
I only trust HSU for SUBS and that is my final word, as a proud owner of a 3.3 w turbo.




Among other things, S&V did MOL at <=10% THD while Howard Ferstler cranked up until the sub started to sound objectionable. What I don't understand from the Ferstler review is why MOL increased @ 20Hz with the turbo employed (compared to no turbo). The opposite occurred in Ilka's recent sub shoot out (i.e. the MK3 w/o turbo was louder at 20Hz than with the turbo). Ilka's measurements square with my own experience using the MK3 with and w/o turbo. At frequencies approximately 16Hz or less, MOL is greater with the turbo employed. All this follows from the differing tuning points when the turbo is/isn't used.

Jim

[Pete_Hsu]

caci, this the response I posted at some other sites regarding this review:

There appears to be a typo in the full lab results. The text of the VTF-3 Mk3 should say: Removing the Turbo extension increased maximum output about 2.3 dB from 25 to 62 Hz and 10 dB at 20 Hz.

The VTF-3 Mk3 in maximum output mode (both ports open, no turbo) would have the following THD-limited output:

32-62Hz (avg): 107.9db (approx.)
25-62Hz (avg): 107.3db
20-62Hz (avg): 106.6db
25Hz: 105db (approx.)
20Hz: 103db
Frequency response: 24 to 85 Hz ±1.6 dB

This is pretty impressive, especially for a subwoofer that is on sale right now for $629!

Regarding the VTF-3 Mk3 with Turbo, there is something strange about the deep bass results (16-25Hz). The THD-limited output at these frequencies should be much higher. For instance, the 20Hz output should be very close between maximum output mode and turbo mode, and 16Hz should be close to the 20Hz output. I noticed that there was a comment made in the review about needing to prop the unit up against the wall to get it to stay in place. This shouldn't be necessary. After all, how else could we test the unit outdoors with good results then? What might have happened is that there was an air leak from the turbocharger due to lack of a good seal between turbo ports and base enclosure. Or perhaps even the carpet grip was not placed underneath the turbo to keep it from moving around. Also, microphone (http://forums.audioholics.com/forums/showthread.php?t=32383#) position may have had some affect depending on where it was placed. It is important to keep the microphone equidistant from all radiating sources (ie. driver and port centroid) to ensure an accurate representation of the actual acoustic output of the subwoofer. Dr. Hsu will be contacting TN to discuss.

I would like to thank Sound and Vision magazine for the very kind review!

[Pete_Hsu]

Regarding the 16Hz measurement from TN in the Sound and Vision review, I believe that the influence of the room is contributing to the strange result. TN has a strong peak at 32Hz in his room, which can be detected by analyzing various sets of data from TN's large room. So when measuring a 16Hz fundamental in this same room using a 10% THD limit, the 2nd order harmonic distortion product is abnormally high, which makes it very difficult to get useable output @ 16Hz with less than 10% Total Harmonic Distortion in TN's room.

[Pete_Hsu]

Hi Jim,

Among other things, S&V did MOL at <=10% THD while Howard Ferstler cranked up until the sub started to sound objectionable. What I don't understand from the Ferstler review is why MOL increased @ 20Hz with the turbo employed (compared to no turbo). The opposite occurred in Ilka's recent sub shoot out (i.e. the MK3 w/o turbo was louder at 20Hz than with the turbo). Ilka's measurements square with my own experience using the MK3 with and w/o turbo. At frequencies approximately 16Hz or less, MOL is greater with the turbo employed. All this follows from the differing tuning points when the turbo is/isn't used.

Jim

HF did not test the VTF-3 Mk3 in maximum output mode in the review, only extended bass mode with turbocharger or with port plug . Also, Ilkka's test data for maximum output uses harmonic distortion limits per the 2010 CEA measurement standard. Note that at 20Hz, Ilkka showed approximately the same max clean output with or without turbo (using CEA limits). HF listens for port noise when determining a maximum clean output, so naturally he was able to push the turbo verson harder @ 20Hz vs. the port plugged extended bass mode.

[JimLely]

Hi Jim,



HF did not test the VTF-3 Mk3 in maximum output mode in the review, only extended bass mode with turbocharger or with port plug . Also, Ilkka's test data for maximum output uses harmonic distortion limits per the 2010 CEA measurement standard. Note that at 20Hz, Ilkka showed approximately the same max clean output with or without turbo (using CEA limits). HF listens for port noise when determining a maximum clean output, so naturally he was able to push the turbo verson harder @ 20Hz vs. the port plugged extended bass mode.


Hi Peter,

In Ilkka's spread sheet he reported @ 20Hz 104.3 dB SPL w/o turbo and 101.6 with turbo. At 25Hz, 108.7 dB w/o turbo and 102.6 with turbo. Are there new data that supersede these?

Jim

[cacihome]

[quote=Peter Marcks;25978]caci, this the response I posted at some other sites regarding this review:

There appears to be a typo in the full lab results. The text of the VTF-3 Mk3 should say: Removing the Turbo extension increased maximum output about 2.3 dB from 25 to 62 Hz and 10 dB at 20 Hz.

The VTF-3 Mk3 in maximum output mode (both ports open, no turbo) would have the following THD-limited output:

32-62Hz (avg): 107.9db (approx.)
25-62Hz (avg): 107.3db
20-62Hz (avg): 106.6db
25Hz: 105db (approx.)
20Hz: 103db
Frequency response: 24 to 85 Hz ±1.6 dB

quote]
Thanks for the quick reply Peter,

I only wanted to say that the 3.3 is by far the best all around subwoofer of all times. Some review magazine companies doesnt agree with that just because it is relatively cheap!!! It is a shame that If it were a sub costing $3,000 the reviews will be made better and the comments about it will be even better than what they are now...I think

[cacihome]

caci, this the response I posted at some other sites regarding this review:

There appears to be a typo in the full lab results. The text of the VTF-3 Mk3 should say: Removing the Turbo extension increased maximum output about 2.3 dB from 25 to 62 Hz and 10 dB at 20 Hz.

The VTF-3 Mk3 in maximum output mode (both ports open, no turbo) would have the following THD-limited output:

32-62Hz (avg): 107.9db (approx.)
25-62Hz (avg): 107.3db
20-62Hz (avg): 106.6db
25Hz: 105db (approx.)
20Hz: 103db
Frequency response: 24 to 85 Hz ±1.6 dB

This is pretty impressive, especially for a subwoofer that is on sale right now for $629!

Regarding the VTF-3 Mk3 with Turbo, there is something strange about the deep bass results (16-25Hz). The THD-limited output at these frequencies should be much higher. For instance, the 20Hz output should be very close between maximum output mode and turbo mode, and 16Hz should be close to the 20Hz output. I noticed that there was a comment made in the review about needing to prop the unit up against the wall to get it to stay in place. This shouldn't be necessary. After all, how else could we test the unit outdoors with good results then? What might have happened is that there was an air leak from the turbocharger due to lack of a good seal between turbo ports and base enclosure. Or perhaps even the carpet grip was not placed underneath the turbo to keep it from moving around. Also, microphone (http://forums.audioholics.com/forums/showthread.php?t=32383#) position may have had some affect depending on where it was placed. It is important to keep the microphone equidistant from all radiating sources (ie. driver and port centroid) to ensure an accurate representation of the actual acoustic output of the subwoofer. Dr. Hsu will be contacting TN to discuss.

I would like to thank Sound and Vision magazine for the very kind review!
Peter what would be the numbers for the Turbo Version then for the:
23-62hz?
20hz?
16Hz?

[cacihome]

caci, this the response I posted at some other sites regarding this review:

There appears to be a typo in the full lab results. The text of the VTF-3 Mk3 should say: Removing the Turbo extension increased maximum output about 2.3 dB from 25 to 62 Hz and 10 dB at 20 Hz.

The VTF-3 Mk3 in maximum output mode (both ports open, no turbo) would have the following THD-limited output:

32-62Hz (avg): 107.9db (approx.)
25-62Hz (avg): 107.3db
20-62Hz (avg): 106.6db
25Hz: 105db (approx.)
20Hz: 103db
Frequency response: 24 to 85 Hz ±1.6 dB

This is pretty impressive, especially for a subwoofer that is on sale right now for $629!

Regarding the VTF-3 Mk3 with Turbo, there is something strange about the deep bass results (16-25Hz). The THD-limited output at these frequencies should be much higher. For instance, the 20Hz output should be very close between maximum output mode and turbo mode, and 16Hz should be close to the 20Hz output. I noticed that there was a comment made in the review about needing to prop the unit up against the wall to get it to stay in place. This shouldn't be necessary. After all, how else could we test the unit outdoors with good results then? What might have happened is that there was an air leak from the turbocharger due to lack of a good seal between turbo ports and base enclosure. Or perhaps even the carpet grip was not placed underneath the turbo to keep it from moving around. Also, microphone (http://forums.audioholics.com/forums/showthread.php?t=32383#) position may have had some affect depending on where it was placed. It is important to keep the microphone equidistant from all radiating sources (ie. driver and port centroid) to ensure an accurate representation of the actual acoustic output of the subwoofer. Dr. Hsu will be contacting TN to discuss.

I would like to thank Sound and Vision magazine for the very kind review!

We beat the ass of that $2,500 subwoofer + shipping
http://www.soundandvisionmag.com/speakers/1853/test-bench-jl-audio-fathom-f112-subwoofer.html
Using the same environment test as the 3.3 in the last review anyway
the Fathom did 80db at 16hz and the 3.3 did 83db at 16hz.

[Pete_Hsu]

Jim, I wouldn't say supercede. Ilkka measures one way, HF another, TN another, and we measure differently from everyone else too. Ilkka's measurement methodology is closest to what we have done. We prefer to measure outdoors at 1m distance, mic equidistant from port centroid and woofer. In my opinion, it is important to have the mic equidistant from all radiating sources to get the most accurate measurement possible of the actual acoustic output. We had to take great pains to make sure that the mic was placed in that position for the VTF-3 Mk3 turbo. At 16Hz and 20Hz we measured even higher output than Ilkka did (up to 3db higher) when using CEA 2010 limits.

Hi Peter,

In Ilkka's spread sheet he reported @ 20Hz 104.3 dB SPL w/o turbo and 101.6 with turbo. At 25Hz, 108.7 dB w/o turbo and 102.6 with turbo. Are there new data that supersede these?

Jim

[Pete_Hsu]

It's very tough to say, caci. The average output from 25-62Hz looks pretty reasonable, and I would expect that to be 105-106db based on measurement data compiled on other similar subwoofers. I would expect 20Hz to be significantly higher than 93db, up to several db higher. 16Hz is difficult to predict because of the strong peak at 32Hz in his room. In maximum output mode, the subwoofer should always be at least 2-3db higher in average output over the 25-62Hz range in comparison to turbo or port plug extended bass mode.

When running a single VTF-3 Mk3 or single VTF-3 HO without the MBM-12, it is best to run them in maximum output mode most of the time for widest dynamic range. When using an MBM-12, definitely use a turbo to take advantage of the best of both worlds in ultra deep extension and very high maximum output levels over the common bass ranges.

Peter what would be the numbers for the Turbo Version then for the:
23-62hz?
20hz?
16Hz?

[JimLely]

Jim, I wouldn't say supercede. Ilkka measures one way, HF another, TN another, and we measure differently from everyone else too. Ilkka's measurement methodology is closest to what we have done. We prefer to measure outdoors at 1m distance, mic equidistant from port centroid and woofer. In my opinion, it is important to have the mic equidistant from all radiating sources to get the most accurate measurement possible of the actual acoustic output. We had to take great pains to make sure that the mic was placed in that position for the VTF-3 Mk3 turbo. At 16Hz and 20Hz we measured even higher output than Ilkka did (up to 3db higher) when using CEA 2010 limits.

Peter,

I mean't new data coming from Ilkka which supersedes the data in his (provisional) spreadsheet.


Jim

[Pete_Hsu]

Jim, I don't think his data will change for the max output tests, unless there was something blatantly wrong with one of the subwoofers tested.

[Ilkka]

Hi guys,

If you would like to ask some questions about the methodology or the results, I'd be happy to answer them.

Remember that those numbers I posted are just a small glimpse of the full results that will be posted in a couple of weeks. :)

My results are not comparable to HF's or TN's results because they are testing in-room which is not as accurate as outdoor environment.

[Pete_Hsu]

Nice to see you Ilkka!

You are exactly right that the CEA max output tests are just a small fraction of data/measurement that is being done by Ilkka. To really get a complete and more accurate picture of performance, one will need to look at frequency response linearity, output compression graphs, etc.

Thanks again for the hard work!

[cacihome]

Hi guys,

If you would like to ask some questions about the methodology or the results, I'd be happy to answer them.

Remember that those numbers I posted are just a small glimpse of the full results that will be posted in a couple of weeks. :)

My results are not comparable to HF's or TN's results because they are testing in-room which is not as accurate as outdoor environment.

In db terms could you tell us how much measured the 3.3wt/wot outdoors at...
16hz?
20hz?
25hz?

Thanks

[mojave]

Here are the unofficial results Ilkka posted at HomeTheaterShack (http://www.hometheatershack.com/forums/home-audio-subwoofers/4294-subwoofer-tests-spring-2007-a.html):

Note: ME = Maximum Extension
MO = Maximum Output

[JimLely]

No significant differences between ME and w/turbo in MOL at any frequency?

[Pete_Hsu]

The benefit of the turbo vs port plugged mode would be much more evident in output compression tests and in subjective tests for audible port noise.

[JimLely]

The benefit of the turbo vs port plugged mode would be much more evident in output compression tests and in subjective tests for audible port noise.



Peter,

Isn't maximum output associated with the threshold of compression, i.e. the point at which additional input results in no (or disproportionately less) additional output?


Regards,

Jim

[Pete_Hsu]

Hi Jim,

Note that the CEA 2010 maximum output data uses specific THD-limits for 2nd order, 3rd order, 4th order, etc distortion products. So the max SPL number according to this methodology is the maximum output before any of the THD thresholds are exceeded for any of these harmonics. The turbocharger would be very effective in combating some forms of dynamic distortion, not necessarily harmonic in nature though.