Impious

So is the 31hz setting a highpass or a lowpass? It makes a big difference.

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Just for reference, determining the "true rms output" of an amplifier isn't as simple as using a clamp meter and DMM. If you are doing this for the purposes of gain setting, the clamp really isn't going to be of much help at all and the entire endeavor will possibly just make things worse for you. Easiest method for setting the gain is to do it by ear. If that is something you feel uncomfortable with, you can use the DMM method (no clamp necessary) previously linked to in this thread. That amp is rated 600w @ 4ohm, and that's probably a little overrated. 1200w @ 1ohm seems realistic, although based on the "max" and 4ohm RMS power rating 1800w is probably what Pyle would tell you the amp is rated for @ 1ohm. Personally I would stick with the 1200w number to be on the safe side, the difference between 1200w & 1800w isn't really that audible anyways. If you use the DMM method of setting the gain, based on 1200w @ 1ohm the target voltage would be 34.64V (again, the test method for setting the gain w/ the DMM and achieving this voltage was previously provided). From there you can tweak by ear. Your crossover settings confuse me. Is it a highpass or lowpass crossover in the Eclipse that you have set to 31hz ??

Like I said in my last response.....I would begin pursuing every legal remedy. If you have his contact information contact his local police department, explain the situation and find out what type of complaint you can file against him. If there is anyone else in your position, I would encourage them to do the same. The more complaints the PD receives the more likely they are to act on them, IMHO. Also find out what you would need to do to file a suit against him in small claims and/or what other options are available. It's fairly evident that waiting for him to rectify the situation himself is getting no where quickly.

I fixed it for you. I'd much rather have, for example, ZED > Sony. Current product lineups, sure. But Sony has a ton of amps in their history which are very high quality pieces of engineering using very high quality parts and construction. Hell, some of them still sell for several grand a piece....someone just posted a build log on here using a pair of them. With the engineering capabilities and capital of Sony they could dominate again fairly easily if they chose....the quantity and margins just aren't there in that market anymore, likely more profitable for them to stick with the more entry level gear they presently offer.

Are you presently running active? If not, how you do plan on changing tweeters? Do the passives have a level setting adjustment for the tweeter?

Amplifier Headroom (click me)

Sorry to hear that unfortunate news and hope he gets through these issues. I understand reality hits hard and you have to deal with it. If the issues are more important than getting those paid enclosures out, shouldnt he just simply give everybody a refund and save the headache. If he can communicate with you, why not his customers? A simple im dealing with some things, give me some time or something would at least ease their minds. Agreed, was wondering the same thing after reading the post. I realize personal issues arise, but at the same time customers have entrusted their hard earned money to his business and have paid for products which have yet to be delivered with little to no updates or attempts at resolution. That becomes a very personal issue for each and every one of them, and possibly leaving himself open to some very real legal ramification. No offense to Andrew, but if I were one of the customers at this point I would be pursuing every legal avenue available to me to recover my money. At this point he doesn't owe an explanation, but he does owe some people either a product or their money. If he's in a position to communicate, he should be in some sort of condition to communicate with these people and begin the refund process. There are certain obligations he accepted when he opened for business and begin accepting customers funds.....short of being in some state of incapacitation, this is one of those obligations.

You are suppose to for couple reasons-1- if you want to keep your bits lasting longer, you will make 2-3 passes per circle. 2- if using MDF, it helps prevent a fire if resistance keeps forming. I didn't know that, but makes perfect sense It also makes for a cleaner cut if you make several passes instead of trying to cut through .75" material in a single pass. Anyways, guess I haven't experienced any of the negative remarks in that video with my Jasper jig Seems like the Toolmaker would be nice as well though.

How or will this change the efficiency?? This^ Generally speaking the 8ohm driver will have a slightly higher efficiency for various reasons depending on the voice coil differences. That said, for a given amplifier the 8ohm driver will also end up receiving approximately 3db less power, and the increase in efficiency will probably not end up being 3db. So if you already have an amplifier, it's possible the 4ohm driver would end up being louder on the same amp even though the 8ohm is slightly higher in sensitivity. If amplifier selection is also open and you can supply the same amount of power to either driver, then the increase in efficiency may be of benefit. Though efficiency won't be the only thing to change.....an increase of efficiency in the 8ohm driver would also necessarily come at the expense of low frequency extension (the "no free lunch" rule, otherwise known as Hoffman's Iron Law). So the short of it is that which version is a better option in any particular installation is going to come down to the needs of that particular installation. And ofcourse this is all conjecture since we don't know exactly what the differences will be in the final driver design until Jacob releases that information.

I see that Fi recommends ported enclosure sizes for a 15" SP4 from 3^3ft to 5^3ft. What will be the differences between a 3^3ft ported enclosure and a 5^3ft ported enclosure with a single 15" SP4? Tuning freq and power (2k-2.5k) the same. Your options are, high efficiency, low end extension, small enclosure size; pick two. Apply that law to Fi's recommendations and you'll answer your own question. That is a good general summary. Specifically what will be the difference between 3^3ft and 5^ft? I.e. 3^ft offers small enclosure size and...... I.e. 5^ft offers high efficiency and.... Low end extension is derived from tuning frequency. Or am I missing something? ...so...... 3^3ft offers a small enclosure size and low end extension? 5^3ft offers high efficiency and low end extension? What is the difference in efficiency between the two enclosure sizes and 2k-2.5k power? Download WinISD or Unibox. Input SP4 parameters. Load the sub into both enclosures. Look at graphs and compare differences. Arrive at the answer to your question.

When there are already dozens of people on the internet with little to no background in driver design assembling "custom" subwoofers by throwing together any parts that will fit and passing them off as these awesome "upgraded" drivers, it's hard not to assume the results will not be similar. Like I said, it's a bias. Glad to see you are planning on taking the intelligent route instead

I guess off hand I don't see any reason an LLT would suffer significantly in the midbass frequencies up to a typical crossover frequency. Inductance and other factors are a larger determinant of high frequency response. I guess the size might require they be placed in some less than ideal locations for midbass response. For example, look at the response between 50-150hz in these two threads, the response is nearly identical. Same sub, different enclosures. The response through the "midbass" is nearly identical, with the added benefit of extended low frequency response and lower distortion. TC2000 sealed TC2000 "quasi"-LLT I'm not trying to sell you an LLT. I just think it would be a better solution. If that's not your cup of tea and you want to stick sealed with a Fi sub, I think I would still probably stick with the SP4. Out of their line up it's probably the best solution for your goals either way. It still requires huge sealed enclosure volumes, but it'll offer the best low frequency extension and maximum displacement capabilities compared to any of their other drivers.

Could you please explain this? Reason I ask is because I've seen quite a few builds with people using using sealed subs and getting flat responses well into single digits. I realize all rooms are different, which is why I'm not opposed to adding more subs to increase output. But I'm thinking 4 Q's (or 2 of the SP4's as you suggested) might be a good start. I guess I'll sort of revise my previous comments. Flat to single digits is "possible".....but with the inherent roll off characteristics of a sealed enclosure and displacement limitations it's not as simple as tossing subs in a sealed enclosure, sticking them in your room and calling it good. It would likely require some substantial EQ work and probably some luck with the room gain. I'm not familiar with the SMS-1 to know what it does, so I honestly don't know what EQ power you have available to you. But the main problem with trying to dig that deep sealed (aside from the inherent frequency response of the enclosure) is that sealed enclosures rely entirely on displacement for generating output. For every one octave decrease in frequency you need to quadruple displacement to maintain the same SPL. So if you are at 110db at 30hz, you would need quadruple displacement to have the same SPL at 15hz, then quadruple it again to have the same SPL at 7.5hz. So between 30hz and 8hz you would need a 16x increase in displacement to maintain the same SPL. This ofcourse doesn't consider the effects of room gain, which will help some. But my guess would be that the people getting flat to single digits with sealed enclosures end up having to reduce the output of the system at higher frequencies to keep the frequency response itself flat that low in frequency.......or they have a significant amount of room gain. Not to mention the drivers are probably operating at (or possibly over) Xmax at those very low frequencies, which increases distortion. Obviously you aren't going to hear the 2nd harmonic with a sub 15hz frequency, but possibly the 3rd, 4th and 5th harmonics are going to start reaching into the audible frequency spectrum which may color the sound if the distortion is severe enough. On the other hand with a LLT you are minimizing excursion at those very low frequencies which reduces driver generated distortion. I'll readily admit HT isn't my forte, I'm just extending basic audio principles over to that realm. My opinion would be an LLT would be a more efficient and better performing means to the end you are trying to achieve.

I would personally recommend SDS. Don is quite easily one of the most knowledgeable and helpful individuals in the sound deadening industry, and on top of that offers some of the best products in the industry. Those two reasons combined make him and his business the best place to spend your hard earned money, in my humble opinion. He'll be able to assist you in purchasing the products that best meet your goals instead of the products that make him the most profit.

Wouldn't recommend it, not sure why you would want to. Even if the designs were similar enough to allow it to be electrically possible you would be limited to the power of the lowest power amp.

Flat to 8hz sealed isn't going to happen unless you have significant room gain. Hell, most electronics aren't going to be flat down to 8hz. Does it have to be sealed? How much room do you have to play with? If I were looking to use Fi drivers for a dedicated HT setup, personally I would be looking more along the lines of the SP4's in an LLT. For example, a pair of 18" SP4's would have more output than a quartet of 18" Q's sealed from 30hz and down, depending on enclosure sizes and tuning the pair of SP4's could have up to 10db more output at various points in that range. That's on slightly less power to the SP4's (5kw on the Sp4's, 6kw on the Q's).

Does it have to be an 8" driver? Do you have space restrictions you are working with?

Congrats Mark !! Enjoy all of the impending sleepless nights

Harmon builds good equipment. They would be decent little subs for what they are. But they are entry level, limited displacement drivers....so performance is going to reflect that. Depending on system and budget constraints there may be better alternatives.

Which particular functions are you confused by?

If you want to start somewhere start with picking up some books. Loudspeakers are physics. Mass on a spring driven by an electrodynamic motor. If you have a general working knowledge of how a loudspeaker functions from a design standpoint and why, you'll have much less "trial and error" and more "trial and experience". No offense, but I don't think Scott/Nick, David or Jacob will have the type of time (and probably patience as a result) it would require to try to mentor someone, for free, about the ins and outs of loudspeaker design when they have companies to operate, subwoofers to build and their own designs and ideas to work on. It's not something you can take an afternoon crash course on and be able to walk out and start designing subwoofers. It's not that simple, too many variations and things to take into consideration. You need to learn on your own first. Once you perform some research on your own, read some books and gain some knowledge I think you'll realize you'll be able to answer a lot of your own questions. Also no offense, but the whole "custom sub" craze currently going on is one of my huge pet peeves. Soooooo many people tossing together random parts with absolutely zero idea about the resulting creation.

Not enough info to allow us to help you, at all.

No, the preamp voltage isn't that important. Set the gain properly and the 2V will be fine. I would help with the settings but I'm not really sure where to start as I'm not sure exactly on your question or where your confused.

Proper highpass setting and installation have a lot to do with it as well. But again, need to know why you aren't happy with the performance of the 6500's.