Quentin Jarrell

UPDATE 9/25/13 As of today all of my initial orders have yet to be built. We are going on a lead time 2.5 times longer than I was quoted. I am being told they are to ship any day now. If you are expecting orders they should ship with in the next few business days. As of right now I am suspending ALL new orders until I have my parts in hand at my shop so I can keep lead time down to a couple days.

I get my maui's from the same place the ole lady gets her prescription ones. They shape them for me in their machine when they come in.

Dayton Ultimax. Will easily get into the mid teens. Regarded by some as the best driver in its category. http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-514

It's gonna be hard to fit an 18 in ~7 feet and still get a low enough response.

rained today so plaster diddnt cure well. Rushed it and pulled the buck off. A few cracks but nothing that isnt fixable.

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haven't seen anderson connectors used in a LLLLLLOOOOONNNNNNNNNNNGGGGGGGGGGGGGGGG time.

The mold is made from plaster of paris. Ive done a TON of mold work in my day. I was in gifted visual arts for all 13 years of school. Off topic but a couple things I have done about 15 years ago. The ole lady and one of several pieces I have done. She's pregnant again and if she makes it through this one I have plans for on when she's 9 months that estimate will take me about 2,000 hrs to complete. The one below took about 700 hrs.

finished the buck and started on the mold today.

not being a dick just telling you like it is. A DD1 is not capable of detecting clipping or distortion accurately. A scope is useless because music is dynamic it causes fluctuations in power thats why speakers and amps are rated at RMS (root mean square----look this term up). secondly it is impossible to set a d class amp with a scope. read here--- http://ap.com/products/accessories/aux0100

no because its just as useless as a DD1

yea?

A DMM at home depot is $10 bucks. Just as useful, actually more useful.

And tens of millions of others have yet to loose a sub. The just spent about $200 less doing so.

More info on this preferably a detailed thread.

I am a bulk commodities inspector. I go just about everywhere in the southeast U.S. where commodities are loaded onto bulk cargo ships or containers.

Without going into details of why, I'll explain why there are truths in both. It takes a certain amount of moving mass weight to get a low. Look and compare any speakers specs from any big brand on the market. There cheaper speakers will not play as low as their higher end drivers. This is due to the weight of the moving mass. Other factors dictate this however those factors are dictated by the moving mass which is directly related to frequency response. For example you can take a JL W1 12 and add mass to the cone and it will have the ability to play lower. This however creates bad side effects due to the motor not being to accurately control this extra mass. Which leads to why some larger drivers may sound sloppier. Most all smaller companies in the same series will use the same size motor a 10 as they do for a 15 or 18. Just like a heavier vehicle needs more horsepower to compensate compared to a lighter vehicle a sub is the same weight. A 15 inch sub will have a heavier mass than a 10 due to the extra material making the cone and the air load that it is pushing against. To fully control this extra mass the 15 will need a stronger motor than the 10. This will vary depending on the expected reponse of the subs but for the car audio application with the typical 32 hertz tuning this is true. This is the reason why a JL W7 13 motor is bigger than a JL W7 8. To combat this I design my motors to handle the weight of an 18 or the largest cone I plan on using. I then add mass to the smaller drivers to compensate for the extra motor force to weight ratio. The more than needed motor force will lower total Q and can give an funky response and give a high gain in response at resonant frequency. This can be observed in larger motored spl type drivers.

I have modeled several enclosures below the show the difference between large signal and small signal T/S parameters. To gather large signal parameters we use what klippel calls LSI (Large Signal Identification). The following is Klippel's definition of LSI: LSI modules measures the linear, nonlinear and thermal parameters of transducers operated in free air or in a sealed or vented enclosure. The transducer is operated under normal working conditions (vertical position and fixed clamped in a laser stand or enclosure). Starting in the small-signal domain the amplitude is gradually increased up to limits admissible for the particular transducer. The maximal amplitude is determined automatically using the identified transducer parameters and general protection parameters describing the thermal and mechanical load. The identification of the model parameters is performed in real time with an adaptive system. It is based on the estimation of the back EMF from the voltage U(t) and current signal I(t)measured at the electrical terminals. The identified model allows locating the sources of the nonlinear distortion and their contribution to the radiated sound. The dynamic generation of a DC-part in the displacement, amplitude compression and other nonlinear effects can be investigated in detail. After the initial identification a temporal parameter variation and long-term thermal effects can be investigated. The data is stored in the stand-alone processor unit and can be transformed via the USB interface to a connected computer for visualization and interpretation. Basically this means the analyzer collects T/S parameters with the transducer under normal operating power in either free air or in an enclosure. We model in the typical free air method at one meter. The transducer below is the DSS Ethos dual two ohm 15. SMALL SIGNAL PARAMETERS (cone moved 1.7mm) FOLLOWED BY LSI Re 3.99 3.99 Qms 7.479 6.69 Qes .712 .57 Qts .65 .53 Fs 41.9 28.6 Mms 362.9g 362.9g Cms .04mm/N .09mm/N BL 23.149 23.149 Vas 36.379L 78.0361L SD 804.25 804.25 cm^2 SPL 87.7 1w/1m 87.7 1w/1m (NOTE: spl efficiency increases as power is applied however we still rate it at 1 watt @ 1meter as most modeling programs use this factor, it will not affect response) GREEN is LSI RED is small signal First up a recommended ported enclosure with small enough volume to fit in a vehicle with tuning to give a little bump in response. 3 cft tuned to 32 hertz Next is a bit larger enclosure to give bump in response in the low 30's with a mid 20's F3. 5 cft tuned to 28 hertz Next up is an enclosure with a maximumly flat response with lowest possible F3 6.7 cft tuned to 22 hertz And finally a sealed enclosure with a qtc of .7 You might say they look too terribly different but look at the difference in enclosure size.

for a few minutes

Time Attak and similar styles >>> SPD's. Getting a floating binding is much better on your knees. I use the Look equivalent that I bought used on CL. 2nd that make sure you get a pedal with a decent rotational float, 5 degrees or so.

WELLLLL being from New Orleans area. I'm sure there is a party rental or something of that fashion that will rent out some type of small DJ set up. Or you could be generous and lend them your home stereo sytem. Rent a small generator and they're all set up.

Keep in mind it's all realistically an approximation of real world performance. It is very difficult to accurately model real world large signal performance due to the number of variables. The above quote doesn't specify exactly how the large signal parameters are defined (I.e. what power, heat, or linear limits are at the point of parameter definition). The large signal analysis above could be a "snap shot" of the driver's parameters at a particular point along it's performance or power curve. If more or less power is applied then the parameter shift from small signal will be different. Based on the same Re on both measurements it doesn't appear significant coil heating is taken into account.....as the coils heats up due to the power being applied Re will increase which will increase Qes....so there's another source of potential difference from the large signal parameters above.This is why small signal parameters are used.....they are a linear measurement, and modeling works best when things are linear. When things become non-linear it becomes very hairy very quickly. That said Q and Klippel are correct, small signal isn't 100% "real world" and large signal analysis is a closer approximation, albeit with it's own set of problems. As he said this is all an approximation. Parameters change greatly depending on a lot of factors. As the cone moves most parameters change constantly. The LSI parameters are a snap shot of the driver at xmax. Since we most expect to play to xmax this is what we use. As pointed out Qes will increase with heat. I wasn't going to go into it but since it was brought up I'll explain why Re was left the same. The point at which the large signals were generated the coil had increased by 46 kelvin (~46 celcius increase from room temperature at start of testing). Coil Re raised to 4.69 ohms. However it took ~350 seconds for the coil to reach this temp. If we were to list this Re customers would first assume their subwoofer is bad if measuring Re while it is cold with a DMM. Also it could cause the customer to load the amp with an impedance too low thinking the sub's impedance was higher than actually is when beginning to play. It's all about getting a close round about approximation. Even the box the driver is in will change the driver's parameters. Large is just a better approximation over small as we don't play our subwoofers to only 2mm. What is important is both tests are done in the same exact manner. The only difference is with large signal the driver is moving as it would be powered up. The reason why Thiele and Small did not do large signal testing back when was they were dealing with much smaller drivers. A driver that is only rated for 5 or ten watts will not see as dramastic parameter shifts at 1 watt versus 5. Not enough to make a difference when it comes to the enclosure.

The below are the Large Signal Parameters tested per a klippel analyzer performed by Patrick Turnmire with Redrock Acoustics. For those who do not know what large signal parameters are, they are Thiele Small Parameters of the driver with a large enough signal to excite the cone to normal operating conditions. These are used instead of typical small T/S parameters because they more accurately represent the driver. When the driver is under power at large excursions the parameters can shift a great deal making small signal parameters not an accurate representation of the true nature of the transducer. Later when I get time I will also post small signal parameters to compare to see how greatly the difference there can be in a given enclosure. Ethos 15 dual 2 ohm subwoofer Re 3.99 (series) Qms 6.69 Qes .57 Qts .53 Fs 28.6 Mms 362.9 Cms .09 mm/N BL 23.15 Vas 78.0361 liters Sd 804.25 cm^2 SPL 87.7 1W/1M xmax 32mm one way based on 70% BL RMS power still to be determined power confirmation expected to be complete 9/20/2013. Testing was done with 2,500 watts rms and the analyzer hit limits due to "running out of preamp" so it will be re-ran. Expect rating to be ~1,800 rms Below is a jpeg of three different enclosures GREEN recommended ported enclosure for car audio applications YELLOW sealed enclosure with system QTC of .7 BLUE ported maximumly flat response with lowest possible f3, maybe for home theater applications?