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[Alex Thompson]

Used TH115s show up from time to time.  Go that way.

I'll try to keep this short.  This is my first impression and a subjective analysis of the two models referenced in the subject.  Actual test data will follow.

In the shop I have 1 x iLF218 4ohm 4000W program and 2 TH115 8ohm 2000W program.

All tests are with the same input voltage (paralleled channels of the same amplifier) no equalization and HPF at 25Hz. Amplifier was Yamaha P7000S run in stereo.  Will see what I have in the shop that can put out closer to the speakers rated power for additional testing.  Will also use only the same amplifier channel for measurements to make sure there is no variation in amp output.

1. iLF218 sounded fuller / deeper vs TH115
2. 1 x TH115 sounded a little louder at higher frequencies, not sure if it was all fundamental or harmonic distortion, sounded a little high to be fundamental.
3. 2 x TH115 paralleled on same amp channel sounded a lot louder at higher frequencies than the one iLF218.
4. iLF218 seemed to have more bottom /sub 40Hz than either 1 or 2 TH115.

[Alex Thompson]

Here are some graphs exported from FuzzMeasure.  Interesting results.  All measurements were made inside because of the wonderful amount of weather we have been having.  Mic positions were close to achieve the best D/R ratio i could inside the shop.

Test one, measurement mic taped to the floor at 2' in front of the grille and centered.  Red is iLF218, Blue is TH115, Green is UCS1.

[Alex Thompson]

Test two: mic at 1" from grille.  Community gets two traces here. Red is iLF218 port, Yellow is iLF218 center, Green is TH115, Blue is UCS1.

[Alex Thompson]

Test three just for fun to see how different subs will play together.
Red = UCS1, Purple = TH115, green = TH115+UCS1 wired parallel.

[Alex Thompson]

To be fair to the other models being tested the iLF218 had the most harmonic distortion.  Also, it seems that from my first impressions the apparent greater volume in higher bass of the Danley TH115 was not HD but must have been from being better time aligned with the main speakers.  Here is a graph of HD.  Red is iLF218, Green is UCS1, Blue is TH115.

[Art Welter]

All tests are with the same input voltage (paralleled channels of the same amplifier) no equalization and HPF at 25Hz. Amplifier was Yamaha P7000S run in stereo.  Will see what I have in the shop that can put out closer to the speakers rated power for additional testing.  Will also use only the same amplifier channel for measurements to make sure there is no variation in amp output.

1. iLF218 sounded fuller / deeper vs TH115
2. 1 x TH115 sounded a little louder at higher frequencies, not sure if it was all fundamental or harmonic distortion, sounded a little high to be fundamental.
3. 2 x TH115 paralleled on same amp channel sounded a lot louder at higher frequencies than the one iLF218.
4. iLF218 seemed to have more bottom /sub 40Hz than either 1 or 2 TH115.

1. Larger 2x18" cabinet with higher tuning, subjectively makes sense unless program with high sub 50 Hz was used.
2, 3. You don't mention any LP filter, the TH-115 has some upper peaks around 500 and 900 Hz.
4.The 2'  response posted indicates below the iLF218 Fb, the single TH-115 narrows to less than a 1 dB difference at 35 Hz.
A pair should increase the LF by around 4-5 dB (the P 7000 only rises from 750 watts at 8 to 1100 at 4 ohms), which should result in far more level below 40 Hz, and similar or greater level above with two. Based on your observations I suspect a polarity reversal in either one of the TH-115 or a cord.

Two feet is really too short of a measurement distance for subs of this size, and the room position seems to be greatly affecting the response curves compared to the published charts.

Always interesting to see some actual measurements !

[Alex Thompson]

1. Larger 2x18" cabinet with higher tuning, subjectively makes sense unless program with high sub 50 Hz was used.
2, 3. You don't mention any LP filter, the TH-115 has some upper peaks around 500 and 900 Hz.
4.The 2'  response posted indicates below the iLF218 Fb, the single TH-115 narrows to less than a 1 dB difference at 35 Hz.
A pair should increase the LF by around 4-5 dB (the P 7000 only rises from 750 watts at 8 to 1100 at 4 ohms), which should result in far more level below 40 Hz, and similar or greater level above with two. Based on your observations I suspect a polarity reversal in either one of the TH-115 or a cord.

Two feet is really too short of a measurement distance for subs of this size, and the room position seems to be greatly affecting the response curves compared to the published charts.

Always interesting to see some actual measurements !

The conditions of the measurements, and reasons were given.  Test tone cut off at 100 Hz with crossover at 80Hz.  Mains switched off during testing.  I'm not interested in what either box will do at 500 or 900 Hz unless there is significant HD up there. 

There is no polarity reversal or bad cords.  I didn't test two boxes together (oops I did say I paralleled 2 TH115 for the subjective test, still not polarity reversal happening) at all except when, just for fun, I put a TH115 next to a UCS1 and as you can see there was addition at all frequencies.  The same cord and amp channel was used for all tests.  All boxes were aligned to the same mark on the floor.  Measurement mic did not move because it was taped down securely to the floor.

I'm not looking for absolute perfect frequency response measurements anyway, only comparative measurements and that I have accomplished successfully. If my actual measurements disagree with what someone believes I should have measured, I'll go with my data.

What has not been done yet is a full power test to see how they might compare in actual use.  At least at low levels, and if I give the TH115 an extra 3dB to account for the nominal impedance difference, one iLF218 beats one TH115.  I still need to figure out how I'm going to test my original hypothesis that: when pushed near thermal power handling limits that the double 18" box should really start to walk away from the single 15".  If that hypothesis is correct than the more sensitive Community box will outperform the Danley by even more than today's testing would indicate.

[Art Welter]

What has not been done yet is a full power test to see how they might compare in actual use.  At least at low levels, and if I give the TH115 an extra 3dB to account for the nominal impedance difference, one iLF218 beats one TH115.  I still need to figure out how I'm going to test my original hypothesis that: when pushed near thermal power handling limits that the double 18" box should really start to walk away from the single 15".  If that hypothesis is correct than the more sensitive Community box will outperform the Danley by even more than today's testing would indicate.

Since the P 7000 only rises from 750 watts at 8 to 1100 at 4 ohms, there is less than a 3 dB difference in the power the two cabinets receive.

Other than the range from 35- 45 Hz, given your test results, I'd expect the iLF218 to still beat one TH115 at higher power levels.

However, a TH-118 would be a different story at high power levels.

[Alex Thompson]

Since the P 7000 only rises from 750 watts at 8 to 1100 at 4 ohms, there is less than a 3 dB difference in the power the two cabinets receive.

I want to test this because I was not running the amp at very high power at all, I'd guess <100 watts for the test tone, much more for a music source.  I am not an electrical engineer and I don't design amplifiers so I'm very unqualified to say that I believe that at lower power levels and only one channel driven the voltage was the same to the 4ohm and the 8ohm load so there would be a 3dB gain.

Other than the range from 35- 45 Hz, given your test results, I'd expect the iLF218 to still beat one TH115 at higher power levels.

I'm going to have to ignore the 2' close measurement and go with my ears on this one.  Perhaps when I get them outside I'll feel differently but the iLF218 sounded like there was more in this range.

However, a TH-118 would be a different story at high power levels.

Based only on published specs, I'd totally agree.  The TH118 beats almost everything on the market in dB/Ft^3 but it does not beat iLF218 it $/dB.  Since I'm more short on $ than Ft^3 I'd go with the iLF218 if I was ordering today.

My real first choice (based only on specs.) is the Danley DBH218 which beats them all in SPL, f3, db/F^3 and $/dB unfortunately I have this problem of sometimes needing to stack so a single bigger box vs 4 doesn't work well for us.

[Ivan Beaver]

Since the P 7000 only rises from 750 watts at 8 to 1100 at 4 ohms, there is less than a 3 dB difference in the power the two cabinets receive.

Of course at levels  up to a dB or so below max output, then going from 8 to 4 ohms would yield a 3dB increase.

It is just the "max output" in which the power does not double.

Al the P7000 is not that great of an amp-especially for subs.

Back in my contractor days we used 2 basic amps in that power range-the P7000 and the Crest CA12.

The CA12 was still a budget Crest amp-but we offered it as an upgrade to the P7000 if the budget allowed.

On many jobs we used the same speakers and all the jobs with the Crest just had more "oomph" to the sound.  It was just more impactful-dynamic-punchier etc.

The P7000 was clean enough-but there was just "something missing" when pushed a little bit.

Those were my observations-based on a number of different installs.

No I never did a side by side test on the two amps-so take it for what you will.

[ProSoundWeb Community]