2001 Honda S2000 Build Thread
05-01-2012, 09:20 AM
#41
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Yeah, I was thinking whether I should post the more technical stuff here on S2ki, I'm not sure how much people dig it.
I was also quite skeptical as to whether these are going to work out. It was a good risk after all. In a bigger car I'd probably use 4 of my Vifa 12" subs to replicate this push pull in a hand built manifold. It's not as cool but it would have even nicer properties. The S2000 is a tight can, you can't beat the LAT packing job. Try fitting 12 7" subs in a push pull in the S.
I was also quite skeptical as to whether these are going to work out. It was a good risk after all. In a bigger car I'd probably use 4 of my Vifa 12" subs to replicate this push pull in a hand built manifold. It's not as cool but it would have even nicer properties. The S2000 is a tight can, you can't beat the LAT packing job. Try fitting 12 7" subs in a push pull in the S.
05-01-2012, 08:40 PM
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Yeah, I was thinking whether I should post the more technical stuff here on S2ki, I'm not sure how much people dig it.
I was also quite skeptical as to whether these are going to work out. It was a good risk after all. In a bigger car I'd probably use 4 of my Vifa 12" subs to replicate this push pull in a hand built manifold. It's not as cool but it would have even nicer properties. The S2000 is a tight can, you can't beat the LAT packing job. Try fitting 12 7" subs in a push pull in the S.
I was also quite skeptical as to whether these are going to work out. It was a good risk after all. In a bigger car I'd probably use 4 of my Vifa 12" subs to replicate this push pull in a hand built manifold. It's not as cool but it would have even nicer properties. The S2000 is a tight can, you can't beat the LAT packing job. Try fitting 12 7" subs in a push pull in the S.
Impressive sub setup!
05-06-2012, 12:30 PM
#44
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Technical Review of the 12" Vifa trio vs. the Tympani LAT700
1 Week in review:
Nothing but good things to add for the LATs. At high output I've noticed there is no loss of composure with the amount of power I run. The increase in output is very linear and I can't pick up any distortion increase with output. This was quite evident with the Vifas at high output. The overall Q would increase noticeably, it would dig a little less deeper and the vibrations were really noticeable. Not so with the LATs, I'm fairly convinced I do not have enough power to get close to their limits. Something between 1500w-2000w would make the LATs tap out, my 850w doesn't seem to push then into audible distortion at all. That's not to say it doesn't satisfy my output requirements but I'm not making full use of their displacement capabilities. In WinISD simulations 850w gets them to 12mm of excursion. That's not accounting for the fact that my amps never see 14.4V so power is lower, there is some loss of power to heat in the VC, and the suspension tightens a bit too by then. So maybe I'm driving them to 10mm at full tilt. Way below the 16mm they are rated at.
With conventional drivers the vibration and resonances become an increasing problem with output, not so with the LATs. The listening experience is completely different. Output can be increased at will so it seems the full twist of the gain knob is accessible. There is no this sounds better this loud and no more, it opens up different frontiers for high output listening. The vibrations that remain are not as correlated with the melody so the rattles that still exist are not as bothersome. I don't think the brain writes them off as distortion sometimes, but mere background noise so it tunes it out easier.
In my car at least the LATs make it easy to cross high: 100hz. I never felt the impulse to lower the crossover. Even so, the door speakers sound aweful by comparison. Cannot wait to swap them out with some LAT 250s.
NOTE: As far as empirical testing goes. To show the benefit of the LAT design two tests should be done. One is high order harmonic distortion to show the reduction in rattles, vibration, and resonance. A THD measure for 6th order and above would be great. Additionally, I think the increase in HD of all types is much slower with the LAT as output goes up. For this one would need a mic that can record HD at over 120db. The Omnimic I use has no such features so the tests I presented are better geared for comparing the actual raw drivers inside than the entire design ability. I do not have the ability to show the benefits of the force cancellation push-pull. It seems that two LAT700s are perfectly capable of matching the raw driver ability of three high quality 12" woofers. Some woofers may dig deeper than the LAT, like the Vifas but the average HQ 12" will be very comparable.
Omnimic Results
Frequency response
Vifa Black LAT Red
Harmonic Distortion
97db
Vifa
LAT
102db
Vifa
LAT
107db
Vifa
LAT
112db
Vifa
LAT
Bass Decay
97db
Vifa
LAT
107db
Vifa
LAT
Testing results thoughts:
SPL
The LATs are about 3db down for the same volume on the deck. The impedance loads are 1.33ohm for the Vifas and 2ohm for the LATs. The Clarion class G amp is actually more powerful at 2ohm than 1ohm but none of this adds up to even .5db difference. So the LATs are more innefficient. Little surprise here, they have more movable parts, the cones have massive strengthening ridges, the voicecoils are beefier so they weigh more, and then there is the mass of the connecting rods. Even carbon fiber weighs something. This translates to about 2x the power requirement.
The coils are supposed to carry on 2kw by IEC ratings so it won't overheat. That's more than 4 times the Vifas' combined power handling 450w vs. 2kw. It will however increase draw, amps work harder, I can hear the fan turn on from time to time, and for some setups the amps might be insufficient.
Frequenecy Response
The Vifas are well known for the wiggle at 27hz or so, it's no surprise that the LAT surpasses it there. Otherwise the ultra low FS (18hz in the white sheet plots) gives the Vifa the edge in extension.
Harmonic Distortion
Over 30hz the HD is nearly indistinguishable. Bellow that the Vifa has much better HD. This is really unusual, HD drops from 30hz down, testament to the low end capability of the NE construction. I don't know a 12" that diggs as deep as this one.
Decay
Seems like the LATs have the edge, especially where the wiggle in the Vifa's impedance plot shows up as a resonance in the upper 20s.
All in all the LATs seem perfectly capable in this comparison. It's true that sub 30hz the Vifa owns, but this is unusually good performance. The LATs are nearly identical to the AE IB12s I had in FR and HD albeit with a much lower sensitivity. The big tradeoff here is fewer rattles vs. sensitivity. If you have the power available it's nice to reduce rattles. It certainly won't stop me. I'm thinking of upgrading my sub amp next to feed it a bit more juice. The ability of these Vifa NEs to dig deep does seem really good, and I will miss it.
1 Week in review:
Nothing but good things to add for the LATs. At high output I've noticed there is no loss of composure with the amount of power I run. The increase in output is very linear and I can't pick up any distortion increase with output. This was quite evident with the Vifas at high output. The overall Q would increase noticeably, it would dig a little less deeper and the vibrations were really noticeable. Not so with the LATs, I'm fairly convinced I do not have enough power to get close to their limits. Something between 1500w-2000w would make the LATs tap out, my 850w doesn't seem to push then into audible distortion at all. That's not to say it doesn't satisfy my output requirements but I'm not making full use of their displacement capabilities. In WinISD simulations 850w gets them to 12mm of excursion. That's not accounting for the fact that my amps never see 14.4V so power is lower, there is some loss of power to heat in the VC, and the suspension tightens a bit too by then. So maybe I'm driving them to 10mm at full tilt. Way below the 16mm they are rated at.
With conventional drivers the vibration and resonances become an increasing problem with output, not so with the LATs. The listening experience is completely different. Output can be increased at will so it seems the full twist of the gain knob is accessible. There is no this sounds better this loud and no more, it opens up different frontiers for high output listening. The vibrations that remain are not as correlated with the melody so the rattles that still exist are not as bothersome. I don't think the brain writes them off as distortion sometimes, but mere background noise so it tunes it out easier.
In my car at least the LATs make it easy to cross high: 100hz. I never felt the impulse to lower the crossover. Even so, the door speakers sound aweful by comparison. Cannot wait to swap them out with some LAT 250s.
NOTE: As far as empirical testing goes. To show the benefit of the LAT design two tests should be done. One is high order harmonic distortion to show the reduction in rattles, vibration, and resonance. A THD measure for 6th order and above would be great. Additionally, I think the increase in HD of all types is much slower with the LAT as output goes up. For this one would need a mic that can record HD at over 120db. The Omnimic I use has no such features so the tests I presented are better geared for comparing the actual raw drivers inside than the entire design ability. I do not have the ability to show the benefits of the force cancellation push-pull. It seems that two LAT700s are perfectly capable of matching the raw driver ability of three high quality 12" woofers. Some woofers may dig deeper than the LAT, like the Vifas but the average HQ 12" will be very comparable.
Omnimic Results
Frequency response
Vifa Black LAT Red
Harmonic Distortion
97db
Vifa
LAT
102db
Vifa
LAT
107db
Vifa
LAT
112db
Vifa
LAT
Bass Decay
97db
Vifa
LAT
107db
Vifa
LAT
Testing results thoughts:
SPL
The LATs are about 3db down for the same volume on the deck. The impedance loads are 1.33ohm for the Vifas and 2ohm for the LATs. The Clarion class G amp is actually more powerful at 2ohm than 1ohm but none of this adds up to even .5db difference. So the LATs are more innefficient. Little surprise here, they have more movable parts, the cones have massive strengthening ridges, the voicecoils are beefier so they weigh more, and then there is the mass of the connecting rods. Even carbon fiber weighs something. This translates to about 2x the power requirement.
The coils are supposed to carry on 2kw by IEC ratings so it won't overheat. That's more than 4 times the Vifas' combined power handling 450w vs. 2kw. It will however increase draw, amps work harder, I can hear the fan turn on from time to time, and for some setups the amps might be insufficient.
Frequenecy Response
The Vifas are well known for the wiggle at 27hz or so, it's no surprise that the LAT surpasses it there. Otherwise the ultra low FS (18hz in the white sheet plots) gives the Vifa the edge in extension.
Harmonic Distortion
Over 30hz the HD is nearly indistinguishable. Bellow that the Vifa has much better HD. This is really unusual, HD drops from 30hz down, testament to the low end capability of the NE construction. I don't know a 12" that diggs as deep as this one.
Decay
Seems like the LATs have the edge, especially where the wiggle in the Vifa's impedance plot shows up as a resonance in the upper 20s.
All in all the LATs seem perfectly capable in this comparison. It's true that sub 30hz the Vifa owns, but this is unusually good performance. The LATs are nearly identical to the AE IB12s I had in FR and HD albeit with a much lower sensitivity. The big tradeoff here is fewer rattles vs. sensitivity. If you have the power available it's nice to reduce rattles. It certainly won't stop me. I'm thinking of upgrading my sub amp next to feed it a bit more juice. The ability of these Vifa NEs to dig deep does seem really good, and I will miss it.
05-06-2012, 01:00 PM
#45
05-06-2012, 04:07 PM
#47
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Changing subs is easy in my setup. I just make a new straight baffle and bolt it to the cage, here is the cage again:
This time around the subs don't need a baffle to do much else either than support their weight and separate front and rear waves so I made it out of single 3/4" MDF. It vibrates a whole lot less than the 3x 3/4" birch board I had for the 12"s.
The challenge was to get them to fit between the trunk support arms. They are roughly 39" wide. I overlapped them and that gave me 37.75", still .75" too wide. Next I removed the middle endcaps and used silicone to make sure there is no gap for the air to go through. That's why it looks ghetto in the middle where they meet. Ideally I should design a one piece endcap for the middle that's airtight as well.
This is how one of them looks like with both endcaps on:
This time around the subs don't need a baffle to do much else either than support their weight and separate front and rear waves so I made it out of single 3/4" MDF. It vibrates a whole lot less than the 3x 3/4" birch board I had for the 12"s.
The challenge was to get them to fit between the trunk support arms. They are roughly 39" wide. I overlapped them and that gave me 37.75", still .75" too wide. Next I removed the middle endcaps and used silicone to make sure there is no gap for the air to go through. That's why it looks ghetto in the middle where they meet. Ideally I should design a one piece endcap for the middle that's airtight as well.
This is how one of them looks like with both endcaps on:
05-14-2012, 12:15 PM
#48
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Great thread, excellent work
Nice to see some one try and overcome the obstacles the S presents. I was leaning towards not upgrading the sound in my S because of the limited space but you have sparked my interest and curiosity so I will have to tackle this sometime soon
Nice to see some one try and overcome the obstacles the S presents. I was leaning towards not upgrading the sound in my S because of the limited space but you have sparked my interest and curiosity so I will have to tackle this sometime soon
05-14-2012, 02:57 PM
#49
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Thanks! I have to redesign the whole cage, I figured out a way to move them in 3-4 inches which would basically give back the entire trunk and trunk springs. So no real loss of practicality. If you use that UL12 use it in IB, there is no way to bottom it out and you'll need all the low end extension you can get.
05-14-2012, 07:14 PM
#50
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Thanks! I have to redesign the whole cage, I figured out a way to move them in 3-4 inches which would basically give back the entire trunk and trunk springs. So no real loss of practicality. If you use that UL12 use it in IB, there is no way to bottom it out and you'll need all the low end extension you can get.