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HSU VTF-3 MK3 giving big differences in SPL on test tones

post #1 of 20
5/30/09 at 12:59pm
Thread Starter 
I just received my HSU VTF-3 MK3 sub. Wow, Impressed! This is only my second sub and the first was just a toy compared to this.

I have a couple questions about calibration and what I'm supposed to see for the SPL when playing test tones.

I read the manual, but it doesn't go into much detail about the test tones on the included CD. In particular, it says to play a 50 MHz tone at 75 Db ... which index number is that on the CD? It also says to play 4 1/3 octaves above and below the crossover (set to 80 Hz on my Pioneer Elite receiver). How do you figure out where those are on the CD?

* Last and most curious question... when I play the various tones, my SPL readings vary by 10 db and more from one tone to the next. I'm using the Radio Shack Analog meter. It appears from the HSU owners manual I need to compensate for the meter's drop off at very low Hz, but I think I am seeing variation at higher bass tones as well. Could this be because of standing waves or nodes due to my room? (Not all sound treatments are up yet, but I don't know how much that's going to affect these measurements.)

Thanks for any ideas!
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post #2 of 20
5/30/09 at 1:08pm
The MK3 has a very flat frequency response. So it is not the sub itself.

The problem you are seeing is peaks and cancellation of frequencies in a room. You need an EQ to adjust the peaks (but not nulls)
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post #3 of 20
5/30/09 at 2:47pm
Quote:
Originally Posted by bmcent1 View Post

In particular, it says to play a 50 MHz tone at 75 Db ... which index number is that on the CD?

That has got to be indicated somewhere. IF not, you may want to see if the tracks are indexed somewhere on the HSU site.


Quote:
Originally Posted by bmcent1 View Post

It also says to play 4 1/3 octaves above and below the crossover (set to 80 Hz on my Pioneer Elite receiver). How do you figure out where those are on the CD?

MOst likely the tones on the CD are there in 1/3 octave increments. Again, you are going to need a track index to know which track is which.

There is an Excel spreadsheet posted in the forums at the HSU site that will make the calculations for you. Of course, you need to have Excel and know a little bit about how Excel spreadsheets work.

http://forum.hsuresearch.com/showthread.php?t=3706


Quote:
Originally Posted by bmcent1 View Post

* Last and most curious question... when I play the various tones, my SPL readings vary by 10 db and more from one tone to the next. I'm using the Radio Shack Analog meter. It appears from the HSU owners manual I need to compensate for the meter's drop off at very low Hz, but I think I am seeing variation at higher bass tones as well. Could this be because of standing waves or nodes due to my room? (Not all sound treatments are up yet, but I don't know how much that's going to affect these measurements.)

As you surmised and as chengbin pointed out different frequencies are going to be reproduced at different relative levels due (mainly) to the acoustics of your room. That is the whole point of measuring those 4 frequencies both above and below your crossover setting.
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post #4 of 20
5/30/09 at 3:13pm
I think this is the correct track index for the 1/3 octave tones, bmcent1.

Track#:

09 = 16Hz
10 = 20Hz
11 = 25Hz
12 = 31.5Hz
13 = 40Hz
14 = 50Hz
15 = 63Hz
16 = 80Hz
17 = 100Hz
18 = 125Hz
19 = 160Hz
20 = 200Hz
21 = 250Hz


Not that their calibration method won't work (and perhaps even better), but you may want to invest in a calibration DVD such as AVIA. It will probably be easier.
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post #5 of 20
5/30/09 at 8:34pm
Thread Starter 
Thank you! Exactly what I was looking for.

I've only got about 1/4 (front wall, no sides, just a bit of the back) treated so far, so it might be interesting to measure it now, and then see how much it changes after all the treatments are up.
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post #6 of 20
5/31/09 at 11:32am
Thread Starter 
Okay, so recording a few things here mostly for my own benefit but it might be interesting for comparison later after finishing the room treatments. The stacked OC 703 triangles are up ("bass traps") but all the side walls are bare and the rear wall only has 2" OC 703 from 32" down and, when finished, it will have floor to ceiling 2" OC703.

I turned the volume on my sub to 9 o' clock per the instructions on HSU's forums. Crossover on sub is set to out (off, IIRC). Phase is 0 degrees. Then ran MCACC on my Pioneer Elite VSX-01THX. Here are the results:

2. CH Level
L: -3.5 db
C: -3.0 db
R: -3.5db
SR: -7.5db
SL: -8db
SW: 0db

* Just guessing: I think the sub volume is a bit low, to the receiver is dropping everything else to keep the SW at 0db. I'm going to bump up the volume on the HSU VF3-MK3 sub just a bit to about 10 o'clock and rerun to see how the channel levels change.

These are the rest of the results from the first MCACC run, not sure what they all mean:

3. DISTANCE (I understand this one looks like my tripod was off center by just a bit, another thing that will be changed for the next run.)

L :12'08"
C :12'03"
R :12'01"
SR :5'06"
RL :4'09"
SW :13'03"

4. S-WAVE
Filter
f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 8.2 ATT.2 : 3.5db
f.3 :250Hz Q.3 : 6.2 ATT.3 : 2.5db

Filter

f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0db
f.2 :201Hz Q.2 : 8.2 ATT.2 : 3.5db
f.3 :105Hz Q.3 : 2.6 ATT.3 : 5.5db

Filter
TRIM : +0.5dB
f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 8.2 ATT.2 : 3.5dB
f.3 :162Hz Q.3 : 9.8 ATT.3 : 7.5dB

5. Aco Cal EQ
Ch
63Hz: -2.0dB
125Hz: 0.0dB
250Hz: +1.0dB
500Hz: +1.0db
1kHz: -2.0dB
2kHz: +1.0dB
4kHz: -4.0db
8kHz: +1.5db
16kHz: +3db
TRIM: +0.5db

CH
63Hz: -4
125: +4
250: -2.5
500: -1.5
1k: -2.5
2k: +1.5
4k: -3.5
8k: +1.5
16k: +7
TRIM: +2

Ch
63Hz: -2db
125: 0
250: +1
500: +1
1k: -2
2k: +1
4k: -4
8k: +1.5
16k: +3
TRIM: +0.5

CH
63Hz: -1.0db
125: -2.5
250: -0.5
500: +1.5
1k: -2.0
2k: +3.5
4k: -5.0
8k: +1.5
16k: +5
TRIM: +0.5

CH
63Hz: -1.0dB
125: -2.5
250: -0.5
500: +1.5
1k: -2.0
2k: +3.5
4k: -5.0
8k: +1.5
16k: +5
TRIM: +0.5
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post #7 of 20
5/31/09 at 12:01pm
Thread Starter 
With the sub turned up to about 10 o' clock, these are the MCACC results. Maybe the sub should be turned back down a bit (splitting the difference) because while it's closer to the speaker values now, it's -db gain set at the receiver after calibration. I have a lot of reading to do

2. CH Level
L: -4.0dB
C: -3.0
R: -3.5
SR: -7.0
SL: -7.5
SW: -2.5

3. Distance
L :12'11"
C :12'05"
R :13'01"
SR :5'01"
SL :5'0"
SW :13'03"

4. S-Wave
Filter
f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 9.4 ATT.2 : 3.5dB
f.3 :85Hz Q.3 : 4.8 ATT.3 : 3.0dB

Filter

f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 9.4 ATT.2 : 3.5dB
f.3 :120Hz Q.3 : 5.4 ATT.3 : 5.0dB

Filter
TRIM : 0.0dB
f.1 :101Hz Q.1 : 9.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 9.4 ATT.2 : 3.5dB
f.3 :85Hz Q.3 : 4.8 ATT.3 : 3.0dB

5. Aco Cal EQ
CH
63Hz: -2.0dB
125: +1.0
250: -0.5
500: +1.0
1kHz: -2.0
2k: +2.5
4k: -5.0
8k: +2.5
16k: +2.5
TRIM: +0.5db

CH
63Hz: -5.5dB
125: +4.0
250: -1.5
500: -0.5
1kHz: -2.5
2k: +1.5
4k: -4
8k: +1.5
16k: +7
TRIM: +1.5

CH
63Hz: -2.0dB
125: +1.0
250: -0.5
500: +1.0
1k: -2.0
2k: +2.5
4k: -5.0
8k: +2.5
16k: +2.5
TRIM: +0.5

CH
63Hz: -0.5dB
125: -0.5
250: -2.5
500: +1.0
1k: -2.0
2k: +4.5
4k: -6.5
8k: +1.5
16k: +5.0
TRIM: +0.5

CH
63Hz: -0.5
125: -0.5
250: -2.5
500: +1.0
1k: -2.0
2k: +4.5
4k: -6.5
8k: +1.5
16k: +5.0
TRIM: +0.5
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post #8 of 20
5/31/09 at 12:29pm
Thread Starter 
Without changing any of the settings from the last MCACC run (nor changing anything wrt the sub or mic/spl meter placement) here are some results from the HSU CD.

When playing the white noise (about tracks 6 or 7) I need to set my receiver to -13db to reach 70dB on the SPL meter. When playing track 14 (50 MHz warble tone) I only need to set the receiver volume to -23 to reach 70db. That's where the volume will stay for these measurements (-23 on my receiver.)

Here are the straight readings (ie, not corrected per offsets in HSU documentation) from the HSU CD tracks...

Track HZ SPL
----- ----- -----
09 16Hz 75dB
10 20Hz 76db
11 25Hz 76db
12 31.5Hz 78db
13 40Hz 75dB
14 50Hz 72dB
15 63Hz 71dB
16 80Hz 57db
17 100Hz 69db
18 125Hz 72db
19 160Hz 70db
20 200Hz 74db
21 250Hz 73db
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post #9 of 20
5/31/09 at 12:30pm
Thread Starter 
From the measurements, things look pretty flat across the bass range except 80Hz looks really out of whack at 57db. That's right at the crossover frequency on the Receiver.

Any ideas what causes that? Are nulls something that can be cured or helped with treatments?
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post #10 of 20
5/31/09 at 12:37pm
Thread Starter 
I guess this is what a null is, but this is amazing to me!

I just moved the SPL meter forward about 3' and replayed track 16 (80 Hz tone) and measured 76dB with nothing changed on the receiver. So that's telling me there is a 20 db difference by moving 3 feet.

I hope treatments will fix this because the original placement of the meter was right where the ideal seating position was planned. I don't have much flexibility in moving my sub because I'd hoped to put it behind my AT screen and out of sight. The room is small so taking up space by the seating area eliminates 1 or 2 badly needed seats.
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post #11 of 20
5/31/09 at 12:42pm
Changing the sub's main volume is not going to change the other relative speaker calibration levels obtained with MCACC. Basically, you got the same results for the speaker levels with each of those 2 runs of MCACC (I think you said you moved the tripod a bit between runs). So, the first run that set the sub trim to 0.0 dB (IMO) was probably best but either of those is fine.


Quote:
Originally Posted by bmcent1 View Post

I just moved the SPL meter forward about 3' and replayed track 16 (80 Hz tone) and measured 76dB with nothing changed on the receiver. So that's telling me there is a 20 db difference by moving 3 feet.

Exactly. This is one reason why the more advanced auto-CAL/EQ programs use multiple measurements taken at different microphone positions.




If I were you I would run the MCACC and be done with it. Trust me. You will drive yourself nuts taking measurements.
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post #12 of 20
5/31/09 at 9:11pm
Quote:
Originally Posted by bmcent1 View Post

Without changing any of the settings from the last MCACC run (nor changing anything wrt the sub or mic/spl meter placement) here are some results from the HSU CD.

When playing the white noise (about tracks 6 or 7) I need to set my receiver to -13db to reach 70dB on the SPL meter. When playing track 14 (50 MHz warble tone) I only need to set the receiver volume to -23 to reach 70db. That's where the volume will stay for these measurements (-23 on my receiver.)

Here are the straight readings (ie, not corrected per offsets in HSU documentation) from the HSU CD tracks...

Track HZ SPL
----- ----- -----
09 16Hz 75dB
10 20Hz 76db
11 25Hz 76db
12 31.5Hz 78db
13 40Hz 75dB
14 50Hz 72dB
15 63Hz 71dB
16 80Hz 57db
17 100Hz 69db
18 125Hz 72db
19 160Hz 70db
20 200Hz 74db
21 250Hz 73db



what size is your room? mine is 20 feet by 18 feet with 8 foot ceilings...i had a null at 80hz as well with my hsu sub until i got the MBM and added it to my system right near my seats...i use the VTF3HO with turbo for everything below 50hz...another thing you might want to check is that you have the crossover knob on the sub turned all the way up...if its at 80hz that could cause a dip i suppose...or just get an EQ...you can get a behringer feedback destroyer for $100 from partsexpress.com and it works great...there is also the SMS1 from velodyne but its pricey...and theres always the anti mode...cant remember the price of it.

i personally own the BFD and love it...i have perfectly flat response from 80hz down to about 3hz then it finally starts to drop off just a tad...i get tons of room gain...i guess that explains the amazing response i get from 20hz down to 3hz

oh yes...and you may want to check out room eq wizard...its a program for your PC that you hook up an SPL meter to and it will record your frequency response and then you can look at it right there on your PC
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post #13 of 20
6/1/09 at 8:55am
Thread Starter 
Quote:
Originally Posted by sivadselim View Post

You will drive yourself nuts taking measurements.

You're probably right ... but that's the "science" part of it for me. I'd like to take the time and get it as close to "right" as I can up front and then forget about it after that.
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post #14 of 20
6/1/09 at 8:58am
Thread Starter 
Quote:
Originally Posted by WaveyD4vey View Post

what size is your room?

About 18' x 11' x 8' ... right now it's carpeted and partly treated for reflections, but there is much more OC703 to hang before it's done.


Quote:


or just get an EQ...you can get a behringer feedback destroyer for $100 from partsexpress.com and it works great...

Thanks for the tip!

If the room needs help even after the treatments are done, that looks like a great option.

BTW, I'm looking for a F-F DB9 gender changer (know I have one laying around here) and once I find that, I should be able to pull 3D frequency plots off the Pioneer Elite receiver. That could be very interesting to see hope the room response changes as the treatments go up. Now if I could only find that little adapter...
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post #15 of 20
9/29/09 at 6:41pm
Thread Starter 
Okay, so pulling up an old post here, but wondering if anyone can give me a layman's summary... did the sound treatments do their job? By far, just from listening in the room, I have to say "YES!" so I know the measurements only mean so much (and there can be error in measuring.)

My room is done now, all sound treatments are up, and I reran MCACC on the Pioneer VSX-01TXH.

Here are the final results (previous results from May in this thread were when just the front wall and part of the back wall were treated)...

2. CH Level
L: -0.0dB
C: -3.0
R: -0.0
SR: -5.5
SL: -5.5
SW: -3.0

3. Distance
L :12'10"
C :10'04"
R :13'00"
SR :5'03"
SL :5'03"
SW :13'01"

4. S-Wave
Filter
f.1 :101Hz Q.1 : 8.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 5.6 ATT.2 : 3.5dB
f.3 :85Hz Q.3 : 3.2 ATT.3 : 3.0dB

Filter

f.1 :101Hz Q.1 : 8.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 5.6 ATT.2 : 3.5dB
f.3 :120Hz Q.3 : 9.8 ATT.3 : 8.5dB

Filter
TRIM : +0.5dB
f.1 :101Hz Q.1 : 8.8 ATT.1 : 6.0dB
f.2 :201Hz Q.2 : 5.6 ATT.2 : 3.5dB
f.3 :85Hz Q.3 : 4.5 ATT.3 : 3.0dB

5. Aco Cal EQ
CH
63Hz: -2.0dB
125: -2.0
250: -0.5
500: +2.0
1kHz: +0.5
2k: +2.5
4k: -4.0
8k: +1.5
16k: +2.0
TRIM: -1.5db

CH
63Hz: -5.0dB
125: +6.0
250: -1.5
500: -3.0
1kHz: -2.0
2k: +4.0
4k: -5.5
8k: +3.0
16k: +4.5
TRIM: +1.0

Ch
63Hz: -2db
125: -2
250: -0.5
500: -3
1k: -2
2k: +4
4k: -6
8k: +2
16k: +5.5
TRIM: -1.5

CH
63Hz: -2.5db
125: -1.0
250: -1.0
500: +1.5
1k: -2.5
2k: +4.0
4k: -6.0
8k: +2.0
16k: +5.5
TRIM: +1.0

CH
63Hz: -2.5dB
125: -1.0
250: -1.0
500: +1.5
1k: -2.5
2k: +4.0
4k: -6.0
8k: +2.0
16k: +5.5
TRIM: +1.0


- - - -

This may sound rediculous, but, what's Q?

It seems most of the Q values went down, also in the channel levels, the offsets go smaller. So (totally guessing) that looks to me like the MCACC EQ has less work to do and the treatments are doing their job?

One thing that is odd, after treating everything, my reverb graph shows shows 63Hz for front channel about 2db higher than all the other frequencies. I don't know if this is just a factor of the tripod being a couple inches different from before (and possibly in a spot where bass is enhanced) or if it suggests something is rattling. I don't hear anything to indicate that, but it really stands out on the graph in Pioneer's Advanced MCACC program.
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post #16 of 20
9/29/09 at 6:53pm
Thread Starter 
Here is a picture of the graph showing the +2db for 63Hz on the Front channel. The center and Surround A channels do not show the same increase, so that makes be suspect it's not a room / tripod placement interaction.



The front speakers are Ascend Acoustics CMT-340 SE, as is the Center. They are all on sand filled pedestals from Ascend Acoustics. The pedestals sit on a stage which is also sand filled (though there is a cavity to the left of the front left speaker which has a access panel to a sump pump; that "lid" is double 3/4" plywood with GG just like the rest of the stage and is screwed down tight to the framing beneath it, the cavity is filled with insulation inside of heavy duty trash bags to take up any airspace in the cavity but leave easy access to the sump if needed.)
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post #17 of 20
9/30/09 at 11:46am
Quote:
Originally Posted by bmcent1 View Post

Here is a picture of the graph showing the +2db for 63Hz on the Front channel. The center and Surround A channels do not show the same increase, so that makes be suspect it's not a room / tripod placement interaction.



The front speakers are Ascend Acoustics CMT-340 SE, as is the Center. They are all on sand filled pedestals from Ascend Acoustics. The pedestals sit on a stage which is also sand filled (though there is a cavity to the left of the front left speaker which has a access panel to a sump pump; that "lid" is double 3/4" plywood with GG just like the rest of the stage and is screwed down tight to the framing beneath it, the cavity is filled with insulation inside of heavy duty trash bags to take up any airspace in the cavity but leave easy access to the sump if needed.)

Swap the left and right front speakers and re-measure. make sure it isn't a speaker issue. If you get the same response, then it either becomes a room issue or an amp issue maybe.
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post #18 of 20
9/30/09 at 12:03pm
Are those tests supposed to be run at 60db?

I thought you were supposed to test FR at reference volume (or at least what you decide is your typical listening volume in your room).

Sorry if it's just me; I'm not that familiar with MCACC or the output shown here...
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post #19 of 20
9/30/09 at 12:25pm
Thread Starter 
Quote:
Originally Posted by In2Photos View Post

Swap the left and right front speakers and re-measure. make sure it isn't a speaker issue. If you get the same response, then it either becomes a room issue or an amp issue maybe.

Oh, good idea. I will try that and report what the result is (might take me a couple days, I will probably wait until I have to pull out the AV receiver for something else because the RS-232 connection for the data download is on the back.)

One thing though, I don't think I saw in the software if I could see the reverb for individual speakers, just for channels. If I swap left and right, wouldn't the combined Front channel still measure the same?
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post #20 of 20
9/30/09 at 12:26pm
Thread Starter 
Quote:
Originally Posted by Noubourne View Post

Are those tests supposed to be run at 60db?

I thought you were supposed to test FR at reference volume (or at least what you decide is your typical listening volume in your room).

Sorry if it's just me; I'm not that familiar with MCACC or the output shown here...

I'm not that familiar with MCACC either, but it's pretty automated. It sets the volume level I believe.

I think you are right that when you are using your own SPL meter, you usually aim for around 80 dB but perhaps MCACC has a different target for whatever reason?
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