Post by: Evan Kirkendall on January 08, 2011, 08:32:19 PM
He bought a pair of JTR Triple 12 tops, and a pair of Orbit Shifter subs.
Specs for the speakers can be found here:
Triple 12: http://jtrspeakers.com/portable/triple-12x/
Orbit Shifter: http://jtrspeakers.com/portable/orbit-shifter/
Tops were being powered with a Crown IT4000.
Subs were being powered with a Crown IT6000.
First up, the Triple 12.
The Triple 12 has 3 handles on each side of the cabinet. It's pretty easy to move around, and isn't overly heavy. It's around the same size & weight as the JBL SRX722/EV QRX212. It's got the usual spray coating as well, and overall has a nice build quality. Some rubber feet on the bottom would be a nice touch though...
On to the measurements:
All measurements were taken ground plane, outdoors.
I have no idea what happened to my screenshot, but it's fucked to all hell. The phase response is pretty flat in the HF, but there were a few weird 180 degree shifts that I couldn't get rid of...
The Orange trace is the raw response with no processing.
The blue trace is the response with an added 24dB LR HPF filter at 80hz.
The Purple trace is with EQ applied.
The Triple 12 seems to roll off fast about 8k, and has a weird dip around 300hz, but is otherwise pretty flat. I ended up using 4 EQ filters total.
EQ1: -3 @ 560hz, Q3
EQ2: -2 @ 5k, Q4
EQ3: -3 @ 8k, Q6
EQ4: +4 @ 9k, Hi Shelf
Nothing too crazy. The box still seems to struggles past 12k, but it's not terrible.
Listening tests:
The Triple 12 has an interesting sound to it. I say interesting, because it's not like what I'm used to hearing. It's not in your face, it's not harsh and it's not what I'd call super smooth. It seemed to have a boxy low mid sound and missing midrange. The top end is crispy, but not super Hi-Fi. Everything is there, it's just, different. I feel these cabs would work well for acoustic type music, not so much rock and roll.
When cranked the HF starts to break up. The 1" compression driver simply doesn't keep up with the rest of the box. You either have to dial the HF back and lose that extension, or simply not turn them up as loud. The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000.
Overall, they're not bad cabinets at all. They're better sounding then some offerings. If I really spent a few days and gigs with them, I could probably get them pretty rockin', but it would take some work. I'd rather have a JBL SRX or EV QRx if I was spending the $$.
Orbit Shifter:
The Orbit Shifter is a single 18" horn loaded subwoofer. It has 2 handles on the bottom, and 2 handle cutouts on the rear. It tilts back onto wheels and is pretty easy to move around with one person. They're very similar in size to a JBL SRX728/Danley TH115.
However, it just SCREAMS DJ grade to me. It needs a full faced grill. It just looks ridiculous to me.
Measurements:
The purple trace is the raw response.
The green trace is with a 24dB LR LPF @ 80hz, and an 18dB BW HPF @ 35hz.
The pink trace is final with EQ.
A single Orbit Shifter does very well from 40hz - 80hz. Due to it's horn loaded nature it does get very efficient above 80hz, and it required a few out of band EQ cuts to smooth it out.
EQ1: -6 @ 100hz, Q15
EQ2: -15 @ 130hz, Q15
EQ3: -3 @ 73hz, Q2
When combined with the Triple 12, the system plays very well together.
Green = sub
Pink = Top
Orange = full range
Listening Tests:
A single Orbit Shifter is not bad at all. It reminds me of the Growler tonality. It's not boomy, but not super tight either. It's very smooth throughout it's bandpass and does very well with dance music. It bangs out the low notes just fine. I was able to bottom it out with some dance tracks, before the IT6000 hit limit. A single Orbit Shifter does seem to have more output than a pair of Growlers. They'd be a good alternative to everyone's favorite MI dual 18's.
Overall, they're good subs. I'd never buy one just because of the way they look, and it's a shame. They are good sounding subs with a good amount of output(I imagine a block of 4 would be very impressive).
Evan
Post by: Caleb Dick on January 08, 2011, 08:46:17 PM
Post by: Evan Kirkendall on January 08, 2011, 09:03:03 PM
| Caleb Dick wrote on Sat, 08 January 2011 20:46 |
Did you try the subs clustered, or only singly? |
Due to time restraints and freezing temperatures, we never got around to doing both subs.
Evan
Post by: Vinny D'Agostino on January 09, 2011, 08:04:47 AM
Evan, what do you use for your music playback? (ipod, CD)
I am just curious if it is the music source that was making the high end break up the way you describe.
I wonder why a 2" throat was not used in the Tripple 12, I had a pair of PAS FT1.2 cabs that had a 12" coaxial design with a 2" throat and I thought those cabs sounded fantastic, especially with vocal reproduction.
Post by: Robert Patch on January 09, 2011, 03:19:12 PM
When we were running the 12x and OS at high volume, do you think part of the problem was running out of power? We had both amps and an electric radiator on one 20 amp circuit. I think I'm going to have to live with the 12x for a while to get a better feel for them.
Post by: Jeff Permanian on January 10, 2011, 10:17:18 AM
| Evan Kirkendall wrote on Sat, 08 January 2011 19:32 |
The Triple 12 seems to roll off fast about 8k, and has a weird dip around 300hz, but is otherwise pretty flat. I ended up using 4 EQ filters total. EQ1: -3 @ 560hz, Q3 EQ2: -2 @ 5k, Q4 EQ3: -3 @ 8k, Q6 EQ4: +4 @ 9k, Hi Shelf Nothing too crazy. The box still seems to struggles past 12k, but it's not terrible. Listening tests: The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000. Evan |
Evan
There is definitely something wrong with your measurements. The Triple 12X is flat to 20khz. That +4db shelf is causing you to reach the compression drivers limits early. I would remove that filter immediately. By the way, the 2011 models now come with a BMS compression driver.
Also, I'm in the process of making grills for the Orbit Shifter.
Jeff
Post by: Jon Waller on January 10, 2011, 11:04:07 AM
| Jeff Permanian wrote on Mon, 10 January 2011 10:17 | ||
Evan There is definitely something wrong with your measurements. The Triple 12X is flat to 20khz... Jeff |
Judging by the pictures, I would guess the microphone is far enough off axis from the coaxial driver on top to be out of the VHF pattern. Coaxial drivers like that are quite beamy above 8kHz!
Post by: Evan Kirkendall on January 10, 2011, 02:26:05 PM
I measured the horn on axis @ 1m, and ground plane at 1 & 2m. The measurements were all consistent. It's not the mic, as it showed the EV and Mackie boxes flatter out to 16k.
Robert,
The only time the amp affected the sound was when it shut down due to low voltage.
Evan
Post by: TrevorMilburn on January 16, 2011, 07:14:02 AM
| Quote: |
The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000. |
I haven't used SMAART myself, so I am not conversant with the displays shown (I saw the 0dB in the display), but were the measurements taken at full power on the IT4000 or at 1w or some other power? I say this because the speakers IIRC are rated at 1600w program which means that if they were being given the full 2000w the IT4000 is capable of at 4ohms and had a 4db HF eq boost applied, the HF would be pushed well beyond it's comfort zone. I would expect most lesser speakers to be screaming for mercy or completely giving up the fight. Also, is it possible that the coaxial MF/HF was mounted in the centre position (it is a sealed unit so can be moved quite easily from what I have read elsewhere) and the measurements were inadvertently not taken on axis at all?
Just curious.
Regards,
Trevor
Post by: George Friedman-Jimenez on January 16, 2011, 09:54:57 AM
| Evan Kirkendall wrote on Mon, 10 January 2011 13:26 |
Jeff, I measured the horn on axis @ 1m, and ground plane at 1 & 2m. Evan |
Following up on Jon's and Trevor's suggestions, when you did the ground plane measurements, how many degrees off the axis of the coax CD was the mic when at 1m and when at 2m?
Post by: Robert Patch on January 16, 2011, 10:08:39 AM
Evan and I are getting together again next month when he gets off tour to do some more test and tune. If he doesn't post the results, I'll do my best to relay them.
Post by: Art Welter on January 17, 2011, 04:01:34 PM
| TrevorMilburn wrote on Sun, 16 January 2011 05:14 | ||
I haven't used SMAART myself, so I am not conversant with the displays shown (I saw the 0dB in the display), but were the measurements taken at full power on the IT4000 or at 1w or some other power? I say this because the speakers IIRC are rated at 1600w program which means that if they were being given the full 2000w the IT4000 is capable of at 4ohms and had a 4db HF eq boost applied, the HF would be pushed well beyond it's comfort zone. I would expect most lesser speakers to be screaming for mercy or completely giving up the fight. Also, is it possible that the coaxial MF/HF was mounted in the centre position (it is a sealed unit so can be moved quite easily from what I have read elsewhere) and the measurements were inadvertently not taken on axis at all? Just curious. Regards, Trevor |
Evan stated:
"I measured the horn on axis @ 1m, and ground plane at 1 & 2m. The measurements were all consistent. It's not the mic, as it showed the EV and Mackie boxes flatter out to 16k."
The posted photo clearly shows the coaxial speaker in the top position.
Unless one is specifically testing for distortion or power compression, speaker testing normally is done at a level that will be 20 dB or so above ambient noise.
With speakers like the ones tested, pink noise with peaks of a watt or two is usually plenty of level to be well above ambient noise. You learn to avoid taking screen captures when dogs start barking, vehicles drive by or fly over, or the wind gusts.
If any of those things happen, they will show up as a reduction in the red coherency trace shown on the top of the screen. Evan's coherency traces all look good within the range under test.
That said, it does not take much wind to make the phase change 180 degrees at 16K, even though the frequency response will stay pretty consistent.
Frequency response testing at high SPL levels just makes the neighbors complain, and gives you no better information.
Art Welter
Post by: Jay Barracato on January 18, 2011, 10:03:42 AM
| TrevorMilburn wrote on Sun, 16 January 2011 06:14 |
I haven't used SMAART myself, so I am not conversant with the displays shown (I saw the 0dB in the display), |
The 0db is the difference between the measured signal and the reference signal. It is independent of the level the speaker is at as long as you are significantly above the background noise (as Art stated).
Post by: Mike Christy on January 18, 2011, 12:28:21 PM
I asked Jeff if the 2010 T-12 has the same HF driver as my T-8s, it does.
My T-8 SMAART plots extended out past 12K, and I hear no evidence of a lack of high frequency from my T-8s. As a matter of fact in some rooms I need to pull 8k down a little for silibance issues.
Maybe a bad xover part/solder joint?
Mike
Post by: Art Welter on January 18, 2011, 01:17:35 PM
| Mike Christy wrote on Tue, 18 January 2011 10:28 |
Very odd. I asked Jeff if the 2010 T-12 has the same HF driver as my T-8s, it does. My T-8 SMAART plots extended out past 12K, and I hear no evidence of a lack of high frequency from my T-8s. As a matter of fact in some rooms I need to pull 8k down a little for silibance issues. Maybe a bad xover part/solder joint? Mike |
Evan's plot shows 8K to be the peak in the HF response.
A cold solder joint on a HF bypass capacitor could make the response droop as shown.
The T-8 is rated 98 dB 1 watt one meter full space, the T-12 101 dB.
If both are +/- 3dB to 20K, the T-8 tweeter has a minimum of 3 dB more HF attenuation.
I doubt Jeff would use the same crossover for a T-8 as a T-12, so seeing some actual plots of both would be informative.
If you and Jeff could post the HF response it could clear up the issue, and may isolate the lack of HF to the particular unit tested.
Could be a driver, crossover, processor setting, or microphone issue.
Post by: TrevorMilburn on January 18, 2011, 06:16:20 PM
| Quote: |
Could be a driver, crossover, processor setting, or microphone issue. |
If the other speakers you guys tested measured OK, I myself would start looking at driver/crossover issues on the JTRs, or, as I alluded to earlier, the location of the mid/high driver. The results seem to be completely at odds with those of other testers (HT & high-end hi-fi) that I have seen who generally sing the praises of the fidelity of JTR products. I know I have worked with brand new equipment,AV/Computing etc. sometimes from manufacturers renowned for their stringent quality control, which has presented strange problems, not always immediately detectable to the naked ear/eye, due to manufacturing faults or other damage such by transportation is totally at odds with the usual production-run models.
However, one has to accept that items sent out specifically for testing should be checked with extra vigilance before despatch simply to avoid such problems - IMHO testers should report their findings to the manufacturer/dealer/importer before publishing just in case a rogue example has slipped past the post-assembly/despatch checks even if only to avoid embarrassment and with the hope that future quality checks are changed and/or improved. I for one would much rather see a reference to such problems as an addendum to a review along with a response from the manufacturer stating what the problem was and what steps were being taken to prevent further such problems than read a belated, often grovelling response, after a review as been published and remarked/commented on by many of the reviewed equipment's target audience/prospective buyers when damage has already been done.
Just my 2 Cents worth (Oh, and I have trained as an ISO/9000 quality auditor)
Post by: Mike Christy on January 18, 2011, 07:00:15 PM
I agree with you Art, the crossover would have to be different in each cab, but it makes little sense to me that he would set the T-12 HF crossover cutoff as it was measured.
Post by: Robert Patch on January 18, 2011, 07:03:43 PM
| TrevorMilburn wrote on Tue, 18 January 2011 17:16 |
I for one would much rather see a reference to such problems as an addendum to a review... |
It was a measured characteristic until Jeff reported that it wasn't consistent with his tests. Evan's off to Brazil now. When he gets back we can check one speaker against the other.
Post by: Dick Rees on January 18, 2011, 07:35:20 PM
| TrevorMilburn wrote on Tue, 18 January 2011 17:16 |
IMHO testers should report their findings to the manufacturer/dealer/importer before publishing just in case a rogue example has slipped past the post-assembly/despatch checks even if only to avoid embarrassment and with the hope that future quality checks are changed and/or improved. |
You are correct, sir.
Post by: Art Welter on January 18, 2011, 07:36:26 PM
Your plot looks little different than Evan’s, it confirms the cabinet is no where near +/- 3 dB to 20 K.
Your plot shows that 20K is more than 24 dB down from the 8 to 9K peak.
Looks like it is headed south around 12K.
Thanks for sharing the graph!
Art Welter
Post by: Mike Christy on January 18, 2011, 08:40:10 PM
Take Care, and respectfully,
Mike
Post by: Art Welter on January 19, 2011, 12:04:33 PM
| TrevorMilburn wrote on Tue, 18 January 2011 16:16 | ||
If the other speakers you guys tested measured OK, I myself would start looking at driver/crossover issues on the JTRs, or, as I alluded to earlier, the location of the mid/high driver. The results seem to be completely at odds with those of other testers (HT & high-end hi-fi) that I have seen who generally sing the praises of the fidelity of JTR products. I know I have worked with brand new equipment,AV/Computing etc. sometimes from manufacturers renowned for their stringent quality control, which has presented strange problems, not always immediately detectable to the naked ear/eye, due to manufacturing faults or other damage such by transportation is totally at odds with the usual production-run models. However, one has to accept that items sent out specifically for testing should be checked with extra vigilance before despatch simply to avoid such problems - IMHO testers should report their findings to the manufacturer/dealer/importer before publishing just in case a rogue example has slipped past the post-assembly/despatch checks even if only to avoid embarrassment and with the hope that future quality checks are changed and/or improved. I for one would much rather see a reference to such problems as an addendum to a review along with a response from the manufacturer stating what the problem was and what steps were being taken to prevent further such problems than read a belated, often grovelling response, after a review as been published and remarked/commented on by many of the reviewed equipment's target audience/prospective buyers when damage has already been done. Just my 2 Cents worth (Oh, and I have trained as an ISO/9000 quality auditor) |
When a speaker manufacturer states a specification, yet provides no chart of the specification, the specification is suspect to start with, IMHO.
When a pair of independent tests as above show similar results showing products that don’t come close to a claimed specification (20K at -3 dB), IMHO the burden of proof is on the manufacturer to provide a frequency response chart supporting their claim.
Post by: Steve Hurt on January 19, 2011, 11:54:30 PM
| Jeff Permanian wrote on Mon, 10 January 2011 10:17 |
Also, I'm in the process of making grills for the Orbit Shifter. Jeff |
Awesome!
I know that grilles aren't cheap when they're half the size of a refrigerator, lol, but grilles will really class up the look of the Orbit Shifters. Good move!
Post by: Robert Patch on January 20, 2011, 03:09:17 PM
Post by: Mike Christy on January 20, 2011, 03:21:04 PM
Post by: Art Welter on January 20, 2011, 04:51:06 PM
| Robert Patch wrote on Thu, 20 January 2011 13:09 |
Here is the measurement position for the 12x. |
The measurement position is not nearly on axis to the HF horn on the cabinet's right side, so a rolled off HF result would be expected as observed.
A tall cabinet measured in the horizontal position laying on the ground is not a valid test for on axis response in normal use. The positioning of the microphone so close makes the test worse.
The response of a HF horn near a boundary is not indicative of it’s response in the air, nor will the response of a mid cone coupled to the ground be indicative of the response in air.
Measurements and EQ settings arrived at from a test with the microphone and a full range cabinet in the position shown are of little practical use.
Art Welter
Post by: Ivan Beaver on January 20, 2011, 05:15:33 PM
| Robert Patch wrote on Thu, 20 January 2011 15:09 |
Here is the measurement position for the 12x. |
I would suspect that the board or whatever the mic is on is affecting the HF response somewhat.
You really need to be using something smooth and larger. I use a 2x2' mirror. Nice and smooth and large enough so the transistion freq to the floor will be better.
Welcome to "measurement world".
Getting accurate measurements is not as easy as it may seem.
Sure you can get "something" but is it correct?
Post by: Jeff Permanian on January 20, 2011, 07:04:34 PM
Triple 12-PRO in the air:
Post by: Jeff Permanian on January 20, 2011, 07:07:40 PM
I pulled down the 135hz peak a few db but then also pulled down 100hz a little in the process.
Post by: Jeff Permanian on January 20, 2011, 07:09:27 PM
2 watt so minus 3db for a 1 watt
Post by: Robert Patch on January 21, 2011, 01:46:33 PM
"The picture posted was one of 5 mic positions, and that was the one that gave me the least coherence in the HF. The cardboard was removed for the measurements posted on PSW, and I picked the best looking results for the forums."
Sorry if my photo was an incomplete picture. This is all pretty new to me.
Post by: Art Welter on January 21, 2011, 02:13:17 PM
| Jeff Permanian wrote on Thu, 20 January 2011 17:09 |
Orbit Shifter: 2 watt so minus 3db for a 1 watt |
Jeff,
“2 watt so minus 3db for a 1 watt “ so -3 dB from the 98.3 Hz 110 dB peak, we get 107 dB.
At 36.6 Hz the graph shows 103.6 dB, keeping in whole numbers 104 dB -3 dB is 101 dB.
Halfway between the two is 104 dB, yet you rate the Orbit shifter sensitivity at 106 dB at 8 ohms in your web site specifications.
2 dB is not a big deal, but a discrepancy.
If the test used a 4 volt signal, that would be 2 watts at 8 ohm.
However, 4 volts is 8 watts at 2 ohm, if the Orbit Shifter speaker was wired at 2 ohms and driven with four volts, the adjusted one watt sensitivity would be 98 dB, which would be a large discrepancy.
Would you please explain the 2 dB (or possibly 8 dB) discrepancy, and tell us some measurement details, such as the voltage used, the impedance (2 or 8 ohm), distance from microphone to speaker, microphone calibration, and distance to any walls ?
Art Welter
Post by: Steve Hurt on January 21, 2011, 02:39:02 PM
I thought my Orbit Shifter were 4 ohm.
Have to check that.
Post by: Art Welter on January 21, 2011, 04:24:53 PM
| Steve Hurt wrote on Fri, 21 January 2011 12:39 |
That's odd. (The spec page) I thought my Orbit Shifter were 4 ohm. Have to check that. |
Also odd that the Growler is rated at 100 dB sensitivity, yet is within a dB or so of the JBL SRX718, rated at 95 dB sensitivity.
Phil’s test results look to be a few dB high overall.
Hopefully, Jeff will clarify.
Post by: Steve Hurt on January 21, 2011, 05:04:19 PM
Post by: Art Welter on January 21, 2011, 07:29:56 PM
| Steve Hurt wrote on Fri, 21 January 2011 15:04 |
If the SRX are rated in full space (and JBL sort of says they are) the difference in subs specs, and at the same time, similarity in Phil's measurements, would make a lot of sense. |
The SRX subs are not measured in full space, neither were Phil's measurements of either sub. His measurements of the JBL are within 2 or 3 dB of the JBL chart, considering his microphones are not calibrated or big buck, that is pretty close.
I recently (finally) got to compare my dual LAB 12" front loaded sub to a JBL SRX 728 outdoors, either the 728 sensitivity is what it is claimed, or my subs magically gained 6 dB
.Post by: Grant Conklin on January 21, 2011, 08:20:17 PM
| Art Welter wrote on Fri, 21 January 2011 18:29 |
I recently (finally) got to compare my dual LAB 12" front loaded sub to a JBL SRX 728 outdoors, either the 728 sensitivity is what it is claimed, or my subs magically gained 6 dB . |
I'd be interested to see the results of that comparison.
Post by: Ivan Beaver on January 21, 2011, 10:17:21 PM
| Grant Conklin wrote on Fri, 21 January 2011 20:20 | ||
I'd be interested to see the results of that comparison. |
http://srforums.prosoundweb.com/index.php/m/612837/6883/#msg _612837
Post by: Jeff Permanian on January 24, 2011, 11:02:35 AM
| Art Welter wrote on Wed, 19 January 2011 18:00 |
But now I know the one watt one meter sensitivity of four front loaded dual Lab 12s is only around 98 dB, I want a pair of DSL TH -218, their sensitivity is 10 dB higher ! Art Welter |
Art, Since you've take quite an interest in my specs maybe you should take a look at other manufactures. DSL doesn't make a TH-218 but they do make a TBH-218, rated at 112db sensitivity, 2.83 volts, 2 ohms so minus 6db for a 1 watt sensitivity.
Post by: Jeff Permanian on January 24, 2011, 11:10:38 AM
| Art Welter wrote on Fri, 21 January 2011 18:29 |
The SRX subs are not measured in full space, neither were Phil's measurements of either sub. His measurements of the JBL are within 2 or 3 dB of the JBL chart, considering his microphones are not calibrated or big buck, that is pretty close. |
| Art Welter wrote on Thu, 20 January 2011 14:20 |
I have attempted to calibrate my Smaart readings, but am not sure if they are absolutly on. I have not attempted to calibrate them with the RTA 420 microphone I was using in the above test. I have written several times that I can’t get my 3 meters to agree at more than one frequency.. Art Welter |
Forgive me if I question the absolute level of your measurements and your correlated sensitivities.
Post by: Art Welter on January 24, 2011, 03:19:16 PM
| Jeff Permanian wrote on Mon, 24 January 2011 09:02 | ||
Art, Since you've take quite an interest in my specs maybe you should take a look at other manufactures. DSL doesn't make a TH-218 but they do make a TBH-218, rated at 112db sensitivity, 2.83 volts, 2 ohms so minus 6db for a 1 watt sensitivity. |
Thanks for catching that mistake
.The TBH-218 is too big, heavy, and physically too deep for me to want to use it, it's the size of four of my subs.
I should have wrote "I want a pair of DSL TH-118, their sensitivity is 10 dB higher".
The TH-118 is rated at 108 dB 2.83 v, so the four ohm cabinet is 105 dB one watt one meter, a pair 108 dB one watt one meter.
One of my dual Lab 12 is around 92 dB one watt one meter from 40 Hz to 100 Hz, a pair is 95 dB, four (eight cones) is 98 dB one watt one meter.
They won't win any sensitivity battles, but unlike most subs, can take full power down to their F3 without lots of distortion.
Art Welter
Post by: Phil Lewandowski on January 24, 2011, 03:27:51 PM
| Art Welter wrote on Mon, 24 January 2011 15:19 | ||||
Thanks for catching that mistake .The TBH-218 is too big, heavy, and physically too deep for me to want to use it, it's the size of four of my subs. I should have wrote "I want a pair of DSL TH-118, their sensitivity is 10 dB higher". The TH-118 is rated at 108 dB 2.83 v, so the four ohm cabinet is 105 dB one watt one meter, a pair 108 dB one watt one meter. One of my dual Lab 12 is around 92 dB one watt one meter from 40 Hz to 100 Hz, a pair is 95 dB, four (eight cones) is 98 dB one watt one meter. They won't win any sensitivity battles, but unlike most subs, can take full power down to their F3 without lots of distortion. Art Welter |
I would say that full 3rd party measurements of the JTR speakers would take care of most of the debate over this, which would be awesome.
Jeff, Are you by chance taking them to the same place that Danley gets their 3rd part measurements done at, because that would be awesome to have as comprehensive as a spec sheet as Danley and would definitely give some big time cred to the specs and cabs.
Take Care,
Phil
P.S. I still don't think we have the Danley model right, it is the DBH-218 I believe is being talked about.
Post by: Art Welter on January 24, 2011, 05:11:11 PM
| Jeff Permanian wrote on Mon, 24 January 2011 09:10 | ||||
Forgive me if I question the absolute level of your measurements and your correlated sensitivities. |
Jeff,
You are forgiven, and I’ll be glad to answer any of your questions
.I have not claimed any absolute levels, though I have plenty of posts saying what my meters read in various situations.
Correlated sensitivities are fairly simple. Measure two speakers under the same conditions, and relative levels are established. If the measurements look like the specs, good!
If they don’t, either the speaker is different due to production tolerances, the measurement positions relative to boundaries was different, or the measuring tools don’t agree.
I compared one of my front loaded 2 x12” Lab subs, nominally a 3 ohm load, to a JBL SRX 728, using the same drive signal, pink noise with a 25 and 125 BW filter, the undriven sub remained by the other sub, and was shorted out. Speaker cords were swapped into the same amp channel, no levels or settings changed.
As you can see, the JBL looks like it’s published specs, so the correlation is good, other than the RTA 420 microphone I used for the test reads a couple dB low at 30 Hz, and the filter reduces the LF output a bit more.
I don’t think you would suggest that a dual Lab 12 is any more than 92 dB , one watt one meter, or the JBL is louder than it’s published specification. This answers the half space or full space question that has been raised before, the SRX line is measured in half space.
The SRX 718 is basically half a 728, so three dB less sensitive, rated at 95, rather than 98 dB.
Phil Lewandowski’s measurements of his Growler and 718 come out remarkably similar to each other, which implies the Growler is the about the same sensitivity as the JBL SRX 718 in the 45-100 range.
The 2007 Prosound Shootout also shows the Growler to be about 95 dB average sensitivity 45 to 100 Hz.
A few days ago, I was surprised to find my “quick and dirty” test position six feet outside my shop door added 4 dB in the octave around 40 Hz compared to the position I did the above test at, about 40 feet from two buildings.
As Ivan Beaver wrote: “getting accurate measurements is not as easy as it may seem”.
Those measurements, and the Orbit Shifter’s 2 dB (or possibly 8 dB depending on voltage applied) discrepancy between your graph and specified sensitivity are why I asked you for distance from microphone to speaker, microphone calibration, and distance to any walls.
Art Welter
Post by: Jeff Permanian on March 01, 2011, 12:54:43 AM
There have been many who have independently validated the Growler's sensitivity.
| Phil Lewandowski wrote on Sun, 27 April 2008 14:48 |
Hey! Now that the weather up here in Cleveland niced up for me!! I was finally able to get outside and take some 1/2 space free air measurements on both the LA400 and the Growler! As a forewarning: These are not scientific by any means but I do think it really opens my eye to what EAW was measuring and I was impressed by how repeatable Jeff's data is on the Growler. This was a very nice and fun learning experience so any advice is welcome! My method: I placed the sub in an open field on my property. I measured 1 meter away from the sub pointed at it, on the ground. The SPL meter was on slow response C-weighted. I kept the sub not in use far away from the one being tested. I used a QSC RMX1850HD to power both. Both on channel one, switching from one to the other when each was tested one at a time. I fed a sine wave using Adobe Audition on a MacBook. I used a volt meter and used a sine wave to get an output voltage from the amp of 2.83 volts. (I just trusted that they are both nominally 8 ohms.) Of course, I didn't run it trough any processing. I didn't use a DSP either just to eliminate any chance of a variable. I went through starting at 150hz going down in increments of 10hz to 100hz. Then at 100hz down to 35hz I measure in increments of 5hz. Here is what I found: EAW LA400 It really enlightened me on where EAW got the sensitivity of 107dB. It seemed like they got it around 150hz. Which, I don't know many, if any live sound comps that cross there subs over that high! So the rating is really irrelevant! What I found is that the sensitivity in the range where the sub would be operating is something more like 102dB 1W/1M. Which puts the -3dB point at about 50hz and the -10 point at about 40hz. At least EAW seemed to get th -10dB point right on the spec sheet. Although it isn't -10 from 107dB.  So the lowest usable frequency from this sub seems to be in the 45hz-50hz range and I think you can really hear that when listening!JTR Growler: This was very interesting because I believe for a spec sheet to be of use, the data should be repeatable. I was impressed by the "repeatableness" of Jeff's +-1dB from 110 to 46hz claim! (Especially with my setup) Also his -1 point was spot on with what I measured! When I asked Jeff about PEQ settings he said there was a hump around 140hz that I found. But he said, that I shouldn't have to bother with that since I am crossing the subs over much lower than that. I did find the -3 point to be about 44-43hz and the -10 point to be 36-37hz range. The sensitivity was right where Jeff puts it @ 100-101dB 1W/1M. So, I definitely give a big kudos to Jeff on really accurate repeatable data! In all, I hope this helps some people who wanted to see some real data on the 2 subs! Again, this was a learning experience for me and I loved it! Thanks & Take Care! Phil Lewandowski P.S. I am trying to figure out how to get everyone to be able to download the Exel file with all the measurements, since I can't attach it here! For now I will just make a make-shift table! It doesn't format well but the 1st column is the frequency, 2nd is the SPL of LA400 and 3rd is SPL of Growler. HZ LA400 Growler 150 107 103 140 106 107 130 106 107 120 106 104 110 106 101 100 106 100 95 105 100 90 105 100 85 105 100 80 105 101 75 104 101 70 104 101 65 103 101 60 103 101 55 101 101 50 99 101 45 96 98 40 92 93 35 88 87 30 N/A 81 |