ncc74656

resin's smell lasts a very long time... im glassing pods for some new speakers on my door panel now and the smell stays for a couple days in the shop after we clean up and thats in a vented shop with a lot of air space.

i was told to play a 1Khz test tone and turn things up until you hear it change pitch. when it does you are clipping the signal. this same principle was explained on BCAE1.com so i assumed it was accurate. the first part about audio being pre clipped came from BCAE1 and from the techs at Fi while discussing and researching distortion. thus there are many songs that are bass boosted so they over drive things right from the head unit. i checked a few MP3's i had on my own computer here in an audio processing program and found the songs to be distorted in their raw wave form.

my boss had a circle jig for his router so yes, we do have one. i had gone searching to find one but no hardware store i went to had ever heard of such a thing so i was just going to try and use a jig saw. the box is nearly complete... crazy long build as i had to run to the store to buy tools neither i nor the shop had, yesterday the shop ran out of glue, today the shop ran out of screws... just lots of hickups. in either case i have the box with in 1/16 of an inch of error on the cuts so its coming together very nicely. i am using some 45's striped across the inside of hte bottom of hte port and then silicone on the rest of the seams. not using any resin. here is a pic of the design: http://i.imgur.com/XXKM1iq.jpg

you always want to set your gains with the car on. to say nothing of voltage drops to your amp when the car is off if you set up everything with the car off and then give another few volts to your amps you are now giving perhaps hundreds of watts extra to your subs/speakers (depending on setup) wich can push them past limits. as for the DDM stuff... i understand that using a meter to get an output voltage and KNOW that the amp is with in spec or to use a O scope to KNOW that the audio its playing is not clipping and with a amp clamp on the power wires you can see how much power the amp is taking and know if its past its limit - this seems like a PERFECT way to do it but... its not. consider that the music you play is always changing, the music from your ipod or off the radio can easily be pre-clipped. add to that at what point your head unit starts pushing past its limit on pre amp voltage and then factor in your amps ability to reproduce a perfectly clean audio source (which it will hardly ever get) and you come to the realization that regardless of what test tone you play or what song you have going with an oscop, the very next song may put it right into the conditions you JUST tested to keep you out of. on top of all that NONE of this tells you if you are properly driving the speaker, just because the amp, head unit, and processors are all with in "spec" does not mean the speaker can take what its being given. its a hard thing to wrap your head around when there are so many "how to set gains" and products that "detect clipping" out there but they just dont pucking work. turn stuff up conservatively until you get the audio sound you want out of your favorite song or if you truly want to play a test tone until you can hear the tone change octave - thats your ~5% distortion point (depending on how good your hearing is). then back it down a bit but dont expect to leave it there. as you play your music change your volume as you hear it distorting. the only time you can set it and forget it is when you set volume and gains with a decent head room e.g. not max volume, more like 3/4. given that and some good quality components then even if you do play a horridly clipped song it shouldn't kill everything.

kool, well that pretty much answers that. my challenge tomorrow will be to cut perfect circles with out a router table for the baffle.

a second question, i have always used screws with pre drilled holes to put boxes together (along with glue of course) and while i understand the glue'd joints become stronger than the wood itself i assumed the screws did aid in the rigidity of the box or at the very least helped build a solid seal with teh glue. I was told that the screws are worthless in box construction and to just use a nail gun to assemble pieces. any input on this?

i use torres most of hte time for box size calcs when a manufacturer has fairly specific specs for cubic, port area, and tuning. if they dont then i use bass box pro and winisd to model things and try to get an idea of how it will respond. id assume both of these programs have such Ql calculations but i will have to check. for this box i think i will silicone the seams on the inside nad perhaps add some 45 degree cuts to the inside of the port. the work and cost of glassing the inside does not appear to be worth it.

ok so the wood does breath. what i take away from that is that if i am building a sealed box for something with high power i would want to glass the inside of it but for a ported enclosure i am unsure if it would make a difference. a direct vacuum plate is a totally different thing from a speaker shoving air along its surface and out a port. i could perhaps see letting resin pool at the bottom of the port to create a rounded area for the air to flow across?

my first thought when i saw the "demo" piece was that it would only work for a sealed box or MAYBE the outside corners of the chamber, farthest from the port. the sample was a single corner cross sectional piece cut from a box so it had a bottom and 2 sides. the inside wood was coated in resin and then there were pools of resin with kitty hair mixed in around all the corners and seams. im certain this is a poor idea for any place there is air flow but if done properly and smoothed out would it provide any real world benefit in this application? given that this is not a project for myself i want to be damn sure that i do everything i can to make this box right for the client. the box is holding 2 12" 1600W 30mm Xmax (one way) subs. The other reasoning for putting resin on the box was to seal the wood from air escaping. now my first thought was the gaps (if any) between joints. this box does not have gaps as an actual table saw was used, however it was then explained that this is to prevent the WOOD itself from air flow. in other words MDF breaths. when i questioned this i was told that if you use a vacuum to lift 4X8 sheets you can lift 2 or 3 sheets through one another with a single vacuum plate. now even IF this is true i would expect the 2.5X12" hole in the box (other wise known as a port) to allow the pressure to escape FAR before the wood would ever breath to this extent? what are your thoughts on all this?

i had a bit more time today to play with settings... i am currently running a 2 way but these crescendos... i have them x overed at 3Khz, anything higher and the vocals that come from them just sound horrid. it almost sounds like the speaker is not fully reproducing the frequencies like when i have heard speakers that are separated from there surround - thats what the crachendos sound like over 3Khz.

my coworker just got in some Xtants. they are 10" and he is running 150W off a JL 5 channel amp and they sound quite nice, clear, linear, and smooth. not as loud as i would like but quite musical. I am running my home computer sub in my truck off my Viper 2500.1D in my truck right now while i decide on new subs. it is far more musical and flat than my SP4 was and while - at the time - i wanted to have ultra low and super loud i feel i have experienced that and wish to build a much more musical system. the sub i have in my truck right now is this one, purchased when i was 16 and has been used for many years, it is in a 4.7 cubic box tuned to 35Hz and i want my new subs to have at least the same linearity as this one but with far more volume as my front stage drowneds it out atm and im not done rebuilding it yet: https://web.archive.org/web/20020605235040/http://www.vidsonix.com/vidsonix/PDS151S.htm knowing this, i am considering buying 2 18" Fi Q's and building them in the recommended enclosure as per Fi. what are your thoughts?

the next thing i want to do is fix my door panels. im replacing my drivers door due to rust issues so its the perfect time to ditch the huge 10" crachendos, there 2" MDF back space, and to remove the 1" spacers i have on my window track in my door. to that end i need to replace them with something that would fit in my install. i was looking at these on a JX360/2: Dayton Audio RS225-4 8" they have very good response from about 90-1khz which is where i would use them, there physical size is FAR less than the crachendos and there efficiency is far greater and they take far less power. what are your thoughts on that speaker as a midbass?

lol, yea i get it. its hard at times (for anyone) to take direct and harsh criticism but all you can do is deal with it and take it in stride. there are times you fuck shit up and all ya can do is move forward. i was waiting on parts and waiting on having enough time to dig into such things. over time i will fix my misunderstandings - there are just a lot of them so it will take a bit.

i was told to never use any battery larger than 1 or 1.5v when testing for phasing. using a 12V battery has a great potential to severely damage or blow the speaker.

i will admit there are days... i had the worst ever audio install come into the shop today, really astonished me at how much worse things can be than my own system. on that note i had a chance to play with my cross over/eq today if only for about an hour. i am absolutely shocked at the difference a good digital cross over can make over a KX3... some very light eq combined with this Xover and i feel like i have a totally different system even tho i have yet to replace ANY parts.

that is what i shall do. ive been experimenting with fiber-glassing enclosures for my door speakers and sound deadening. seeing as i have not done much of this its more of a trial by fire where im just seeing what things sound like. quite literally cut my drivers side door into pieces playing around with all the configurations and such. i am amazed what a difference the sound absorption materials can play even with just slapping a speaker to the door... i had NEVER seen or used them before.

the screw down terminals seem to always present some degree of fraying regardless of how hard you try to prevent them. amps like kicker do have a bit of an over lap to help prevent it but amps like audiobhan, crunch, boss, sony, ect. dont have such devices and its a pita to try and keep the wires all together. perhaps i will try the tinning approach.

from my readings it was mentioned that remote turn on leads should be fused at .5A on all installs. is this standard practice today or was this directed at older decks? i have just never seen or heard of this until i read it. when using a LOC converter (factory head unit to power amps) i read it should be installed behind the deck. is there any reason against installing it off rear speakers in the trunk or else where in the car? assuming what ever speaker outputs you are going to are the right type e.g. not crossed over from the factory deck at an incorrect frequency for your application. edit: question about gains. when setting amp gains i was told that i should max out the bass control on the head unit. that is to say not loudness, bass boost or eq but if the sub has a dedicated sub volume control i should set that to max setting and then turn the deck up to 3/4 to set the amp gains. my thought was that this would put the deck into clipping but i was told this is the only way to get full power out of the head unit when setting sub gains. anyone know anything about this? second edit: i have heard of spade terminals but never seen them. i read that they should be used every time you have an amp that accepts bare wire into its terminal. how many people actually do this? i have been wondering for a while what the best way is to prevent strands of wire from arcing out and this does seem to be a solution. anyone have a better one?

i was ignoring the install, i am currently working on rebuilding it and fixing it. teh SP4 is non function so i was debating if i wanted to recone it or sell the motor which is why i started looking at other subs. Il: i had googled cross overs but was told the websites i had found were incorrect which is why i posted on here to be sure.

M5 i am not ignoring my install, i am rebuilding the front stage and have built different boxes for my SP4. install can not fix a sub that is designed for SPL over linearity and sound quality. given my SP4 is in pieces i am left to either rebuild it and continue to use it or sell it off and replace it with speakers that better fit what i am looking to do. in that regards i am looking into the Q's. when i say i want more quality that is exactly what i mean. i want the audio to be less peaky, have a more fluid response so as that one part of the audio does not cancel out another. i want the subs to be able to reproduce there full frequency range and i do not require a sub tuned to 29hz, even in a 33hz box the SP4 has less than a flat response curve. my coworker who installed 2 10's in his car has a better transient response than my sub does (for obvious reasons of the SP4 being designed more for SPL) and thus i am looking to buy subs more suited to the application at hand. as for the install of my current components i have new tweeters in the mail that have FAR better specs than my lower level alpines. I have 2 mid range speakers that will go in my door and am using Velcro right now to play with position and angle. I have sound absorbing backing coming for the inner doors/floor area and i have a couple sheets of dynomatt that im installing as i find panels that are vibrating. I am ditching the crescendos once i receive these new drivers and then ill be able to actually sit down and start tuning/playing with things. i have a 16 channel digital EQ with cross over network now that is not an old external POT audio control. edit: on a side note, i had an argument with my boss and i swear to god im right about this but he's got me second guessing.... we were talking about cross overs and I thought an active cross over system is done at the preamp level and its considered active because you are actively using pots or digital processors to change things where as a passive system uses capacitors and inducers that sit on the amplified, speaker level outputs and its called passive because you don't change it once you set it. but i was told im wrong and MECP states that active cross overs are at the speaker level output and they are active because its the higher voltage side of the system. ???

i would think that a Q sub would blow a SP4 out of the water with linearity and response given that its designed specifically for that. my BL hit the high notes very well and that was an 18 witch is why i have no second thoughts about going with a 18 Q. the Q has more Xmax so that says to me that it can hit the lows better wich is what the BL was missing. now if the sub is built well and has a strong enough motor should an 18 or 15 be able to reproduce just the same sound quality as a 10 or 12 if all else is equal? i understand the larger the cone the more force is required to move said cone but i am under the assumption that the 18 has that much stronger of a magnet to facilitate this. looking at Fi's website it would appear that the same magnet is used on 15 or 18 variants of the Q and the BL has a stronger magnet and yet less Xmax? the huge xmax on the Q really throws me as i would have thought it would be the other way round. in either case i could do 2 15's to get louder than my 18 is now as it has more cone area and i "should" gain more frequency response over 2 of the same 18's. knowing the 15 i have now sounds very good in my setup but lacks the volume and perhaps a tidge of low end the 15 Q's may be the best option. I have also read that the "size of a sub determines its audio quality" is generally a null rule when dealing with high end audio drivers. I have read of 18's being in sound quality competitions so this has lead me to believe that while perhaps smaller subs will edge ahead a bit on quality of audio and response, the 18's are not far behind (if at all). The space i have in back, current setup, and cost all make me lean towards 2 18's as opposed to 3+ smaller subs. having said this if the 18's are truly going to be atrocious in audio quality then i will have to just build up the system to accommodate the smaller subs.

so i could go with 5 12's or 3 15's to reach the same cone area as 2 18's and gain better frequency responce in the process? so i could go 3 dual 1 ohm and get about 1.5 ohm load. is the frequency response really going to be that much better? it would be about 600.00 cheaper to go 2 18's when you factor in amps and sub prices.

so i should run 4 or more 10's then? i could easily fit 6 of them in the back. that would provide more cone area than the 18's i have read many places that a sub is a sub, a 10 will move at exactly the same rate as a 18 when it comes to frequency responce. size of a woffer is secondary to other attributes. are we now saying that this is not the case? that an 18 will sound noticeably worse than a set of 10's?

more sound quality is exactly what im after. thats why im looking at the Q's. whats wrong with 18 over 12's? i have plenty of space for them.

my SP4 box is at 29hz and it gets CRAZY low but lacks the upper end. i was thinking of placing this sub in the middle of tuning (32-35) and then adding some of those subsonic earth quake boxes for 5-30hz (the ones that alpine made and that other companies make for theaters). in either case the low tuned box just pulls to much out of the higher end and peaks the lows to much. im looking for a flatter response. given that i dont think any box could bring hte SP4 in line with what i want to do.