Impedance curve on db124's

skydeaner

Anyone know where I could get ahold of the impedance curve chart for the db124's, I want to measure the rms output of my amp right now and I need to know what frequency they'll hit certain ohmages at so I can be sure. Right now it looks like it is giving them quite a bit more than 400 a piece and I want to back it down but I can't be sure unless i can see an impedance chart so I can figure it out.

MacLeod

Thats kinda splitting hairs isnt it?

If its pushing the subs too much just tune em back. That would be a lot easier and less hassle.

skydeaner

Well they don't distort at all, really I just wanna see if my amp is putting out it's rated power so I can decide if I am going to get another one or not

neomagus00

humm... well, according to WinISD, it should hit 8 ohms at 34.75 Hz, and 28.5 ohms at 49 Hz... that should be quite accurate enough (trust the 8 ohms figure more)... to check, you should be at 4 ohms at 15.25 Hz, which should be a good figure to know...

exalted512

impedance will change as the sub heats up as well...
-Cody

neomagus00

so do your measurements quickly

skydeaner

Well I have them in a sealed box, which means the impedance is going to peak at resonant frequency right? So doesn't that mean at the 34.5 hz it should be quite a bit higher than 8 ohms... because their fs is sittin at 31hz.

skydeaner

If I pump a 100hz tone into them, can I measure the resistance across the terminals at that point to find out what impedance they are at? Or would that not be accurate?

skydeaner

impedance will change as the sub heats up as well...

hehe its 15 degrees outside, they won't heatup too quick

neomagus00

putting a driver in a sealed box pushes up its Fs, sometimes pretty significantly... so for example, those numbers were for a ~1.4 ft^3 box... this didn't occur to me... what size box are you using (net volume)?

putting a tone through at the same time as measuring resistance is highly unlikely to work - i do believe that the way a multimeter measures resistance is by passing a current through the leads, and measuring resistance to that current... having an existing signal would screw with that...

and even at 15 degrees, the VC will heat up fairly rapidly - more than 99% of the power you're putting into the driver ends up as heat in the VC... so if you're giving them rated power, you're putting out nearly 400 watts of heat... that's about half a horsepower of pure heat, quite a bit, actually...

skydeaner

Wait so, if at 34.75 the speakers impedance is around 8 ohms, that means it is only getting 200 watts instead of the 400 right?

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i understand why you're tryin to do sky, and it's admirable - but a huge pain in the ****.

if you think it's really worth it - by all means continue trying, but i have no idea how to do it properly.

my usual "is the amp doing its job" is to run a 60 hz tone for a sub amp (get a cd with a test tone or make a cd with a test tone - juice it - then throw an rms AC volt meter on it... square and divide by DCR of sub (usually 3.8 or 3.9 for a 4ohm sub) - and call it a day.

skydeaner

Ok with a 60hz tone I got 40.25vrms. So, I took the 40.25x40.25 / 1.625 (2 db124's at 3.25dcr each) and got 996 watts rms coming outta the amp... lemme tell ya, the db124's weren't likin this. But I have an "I blow em they replace em" warranty at fry's so i wasn't real worried. So I am very satisfied with the output on it, and I backed the gains down to where the subs weren't distorting which was at about 35vrms or about 380watts a piece. For a 135 dollar refurb amp, I would say I definitely got my money's worth. The cool thing is that once the SR subs come out I can run it at 1 ohm (if they have a dual4ohm version) and should have enough power for those instead of the db's! Plus even though it's a refurb it comes with a 6month warranty from directed, and if it doesn't break in the first 6 months it probably never will unless abused. I be a happy camper.

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996 - sweeeeet

what is the amp rated at? is that the dei 600d or something that you picked up recently?

skydeaner

it's the 1500d refurb I got from ikesound. It is rated at 800rms at 2 ohms, and 1100rms at 1

I like it a lot, I think I am going to get a directed 2400 200rmsx2 for my fronts and get rid of my kenwood 60x2 Ikesound.com has them on sale for like 73 bucks, and now that I know they come with a 6 month warranty thats a hell of a deal for a 200x2 amp.

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ike sound ROOOOOCCCCKKKKS

i love that place.

skydeaner

Yeah, they are now good friends of mine. I don't see why people always bag on factory refurbished items. Do factory's even troubleshoot down to the component anymore, or do they throw a whole new board in?

PoweredByDodge

depends who you're talkin about.

mtx troubleshoots down to the component and does a good job of it - hell just about all the mtx amps i have that i didn't rebuild myself i got refurbished. and i got a lotta mtx amps.

if you're gonna throw a whole new board in then why even keep the casing? just send the customer a new amp in a new case. same thing.

higher end companies troubleshoot down to the part too because the parts themselves are $$$ and some of those high end amps are hand built anyway so it makes sense.

the thunder 302 that the ex has - circuit **** jacked up the under-extended-warranty repair (if it didn't have 'cheese' i would have fixed it myself to begin with but i figured why bother - let them pay for the parts - i had already figured out what was wrong with it before it went in). well i got it back and it was MESSED UP BAD -- they guy did a horrible sodler job, burnt the board from the soldering iron in a few places... just a mess. after 2 weeks of arguign with CC they sent it back to mtx - guy over there was like "oh my god, don't work on our amps again, you destroyed this, we're going to have to put a new board in" - i was like "dude, i didn't do it - that's courtesy of circuit city." -- he was like "ya, looks like their work". i would have gotten a new amp but they had changed from 8302's to 302's by that time... what i ended up with was a rebuilt blue thunder 150.2 in a 302 case... i wasn't complaining, power output went up. only reason i knew it was a blue thudner board is that all the BT boards were blue in color while thunder boards are either beige or black... thunder X000 boards are all green and black. anywho - back to beer.

skydeaner

lol, sounds like circuit ****. Aren't they going outta business or somethin?

Thom

GM will go under first...

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hahahahaha!

as much as i'm anti-gm, i hate to see them go under... they employ more UAW workers than i can imagine. they're one of the few companies you can still say is the "backbone" of american labor.

god, we gotta start buildin better friggin cars - when it gets so bad that american's won't buy american cars, even if it means putting themselves out of a job, then we're in trouble.


on a side note - the f****** dodge is spitting error codes again - dammit macleod you jinxed me! - and i can't find a dealer to work on it because they've all banned me (wonder why).

code p0138 - so i'm going to replace the rear oxygen sensor and then if it still comes up replace the cat (cat had raw fuel dumped in it a year ago so it makes sense).

i hate my life.

warranties are worthless if no one will work on your car.

neomagus00

and no-one will work on your car why?

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i think i've gone though this all at one point or another. but the short version...

West Herr Dodge of Hamburg NY

---

old man buys his 99 ... gets running boards put on as part of the deal... they damage the lower body panels in doing so... they refuse to fix it... i intervene with my 88, an ozzy osbourne cd, and i believe polk DB 6x9's (woot woot!) and DX10 subs... the result of what i believe was half hangover, half angry me, was that they paid for the repair at a bodyshop of my choice.

bought my 99 from them too... master cylinder was shot - they said "nothing's wrong" -- few days later i hit some woman going about 30 mph because i couldn't stop the truck. took it back to them, "nothing's wrong" they say... i go ballistic - tell them to buy the truck back or hell is going to rain down like nothin they've seen before. eventually a shrewd mechanic decides to dig a little deeper, finds the problem, fixes it after weeks of fighting with them.

was asked to avoid teh dealership if i could - and i didn't wanna go back anyway - never returned.

Walden Dodge (now out of business... I wonder why) of Cheektowaga NY

---

took my 99 there for an inspection... (it was like 7 at night and i needed it that day and they were the only place still open on a sunday or some **** like that). they intentionally dicked around with my steering linkage and then when i refused to pay them to replace half the steering components in the front end, the **** yanked one of my lamp sockets out of the rear bumper and failed the truck for inspection. so i had to buy a new lamp socket and then have my own mechanic do some straightening and realigning up front - but no replacement parts, just getting it all set up again.

filed a police report for property damage - not welcome there.

Northtown Dodge of Amherst NY.

---

I buy the 03 i'm drivin now.

I tell them, "here's like 700 bucks, I'm going to go home, remove my audio and put the 99 back into a respectable interior condition and bring it to you like in 3 or 4 days and then i'll take delivery on my new truck" ... they say "oh no we have professionals, we do audio all the time, we'll remove your stuff." -- i say "um, no... i have idmaxes... 500 dollar each subwoofers... i have amost 4kw rms... i have more than your inferior morons can handle" --- "oh no, we got it covered."

so me and DJ Turbo go there the next day and the "master tech's" look at the truck and go, "lotta **** in here man".

Their way of "doing it right" was to cut the carpet down the middle of the truck with a razor... hack the whole thing up... They then proceeded to yank, kink, and gank on every wire you could think of. In the process they tried to remove the alarm themselves. Then they got mad when the truck wouldn't start... I said "um, you know that's by design, if the alarm is removed, the truck won't start... its anti-theft"... so i had to spend hours re-doing what they **** up -- and i had to work in their **** bay with their **** tools. then they got confused by the double battery setup and wanted both batteries... i was like "um, no - you get the battery from the new truck... and the cables too - the 0 gauge all comes with me..." -- theyre like "well where are we suppposed to get alternator cables and starter cables and all that **** from and battery terminals..." -- i'm like "i dont really give a **** - you **** wanted it done today - so here, choke on it... i told you to wait a few days and i'd do it all properly to be as close as OEM as possible.".

Then the **** pick up the sub boxes and drop one of them out of the truck... the kid goes "oh don't worry - just the box got nicked... those aren't good subs anyway, where'd you get those, ebay?"

i'm like, "you stupid **** suckers, those subs weigh about 40 pounds, they cost me 500 bucks each plus shipping, they're rare as hell because they company that builds them by hand can't get parts due to a shipping dock worker's strike... they're 1,000 watt rms SQ competition subwoofers and you stupid **** just knocked a motor structure outa wack probably..." --- sure as **** - a couple weeks later when i got them installed in the 03 -- both voice coils were rubbing the former/magnet... i had to scrap the subs (sold them on ebay for 125 each -- my mother was furious with me - and i literally was near tears).

during this mess making that they did, they destroyed some of my amp rack **** and wiring and just made a total mess of a truck that i put a lot of work into - i put my soul into... every project i do, my mom helps me... she gets me tools, she holds stuff... she learns stuff along the way - she's no installer, but she's a real nice lady and she likes to get invovled with things, and to be honest, i couldn't do half of what i do without a 2nd pair of hands and somebody lookin out for me... well she got upset about the way they were hacking up the truck and she said something to the salesman like "can't you be more careful please" - and he's like "it's not your truck anymore, and why don't you go in the lounge and have some cookies." -- now, my mom's fat... let's not mince words here... you don't tell a fat lady to go eat cookies.... that ain't cool... so she started crying.

i have never, ever, in my entire life, been more furious with another human being. wait - i have... because of the same dealer... but at a later date.. anyway... i got right up in his face, spit flying from my lips, blood vessels extruding from my forehead, and my eyes all googly - and made it very clear that he would apologize, leave, and not come back, or i would make him wish he did. we completed removing everything hours later... it was a mess.

i then took my new truck home feeling like i lost my soul. wishing i had never bought it.

i then had a huge problem with said new truck - it was firing unsparked gas out the exhaust ports - blew a hole in the muffler - somewhere along all of this - they said "nothings wrong with the truck.. so i leave... blah blah blah - big old backfire with a ball of firey smoke and **** - my mom freaks out - she cries (ugh.. women)... state trooper escorts me back to the dealership *ya this is a bad story* -- in the middle of it all, i hop outa the truck, throw the keys at the service guy and say "fix the **** truck, now... i jsut left here, u said it was fine.. it aint.. fix it - i'm having a smoke" -- was about to walk out, my mom was still kinda dryin her eyes a little, and the guy behind the counter is like "what are you crying for? and starts giggling at her" -- so i went insane. i don't remember much of what was said but it was ugly... and the entire dealership floor heard me... there were women in there that after i was done talking they looked at the service man and just gave him that evil death look like "you should be ashamed of yourself you pig". the service manager then warned me that another outburts would lead to me being expelled.

they fixed it like forever later...

somethign went wrong w/ the old man's truck - the air conditioner - we go in there... they do the warranty work - or start to do it - they break his grille in the process.. snap it clean off its brackets -- they refuse to fix it because its "aftermarket" - i said "its a direct replacement for the original.. the reason i have it is because my own mechanic busted one a couple years ago, and he's a good guy, not you like ****, he's a nhonest dude and i didn't wanna stick him with a 400 dollar factory grille bill so i got some freebies outa 'em and went and bought the aftermarket grille from the internet .... and you **** broke this one now... so you're payin for it - or at least another aftermarket one..." -- service manager is like "you're insulting me... we don't break things here" - i said "you're doina good enough job insulting yourself you stpuid ****".

so i got thrown out after a lot more yelling. i called chrysler corporate and they paid for me to take the truck wherever i wanted and apologized for the dealership. but it was a one time courtesy - they want me to find a dealership to deal with now because they're not going to pay for repairs out of pocket anymore.

I still like DJ Turbo's comment to the salesman when he made my mom cry. "way to go on your first sale, you made the guy's mom cry, ya, you're gonna be a winner".


so i got nuthin...

skydeaner

LOL.... thats all I can say.

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ya - and then THAT SAME NIGHT - apparently somebody must of thought my truck wasn't "all junk subs" because that night in the dealer lot after all my **** was removed, somebody broke into the truck, smashed the windows and went huntin for **** but found nothing .. they had it on surveilance video.

apparnently the Go N Def Idmax bumpin flame red ram with big old honkin meanie teeth (or as my friend would call them "teefers") on the front had some fans.

god, i'm getting emotionally **** up right now.

i'm like - still totally in love with Kenny Sexy... dude, this is so scary.

I'm like "not over my old truck"...

maybe that's why i'm mad at my new truck, because i never got over my old truck, or maybe because in order to get the new truck i had to not only leave the old truck but participate in it being destroyed in such a manner... so ungracefully - it didn't get to go out with a bang or in style or gracefully ride into the sunset, it got gutted and auctioned off to the lowest bidder, after i put all that time and effort into makeing it so pimp... from the outside -- it was a **** animal man... low stance 2wd, jacked up back end 2 1/2" .. dual exhaust that just GROWLED man... big old 360 with a this "i'm in a bad mood" sound to it - ARE fiberglass toneau that mimmiced the hood... and this haunched over "wolf on the prowl" look to it... god i miss it. not as much as i missed old blue -- wait.. maybe more ... i'm friggin sad.

attached is one of the few pics i have of him.

i'm seriously havin heartache issues over this... god dammit. i think i need to never get rid of my trucks.. i mean, keep em like 10 years until they're just **** and then put them in a big garage and just keep them

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you know what - it was a way better **** truck too...

cruise, tilt, power locks and windows.

heated mirrors and high-mid grade interior.

better suspension, MUCH better suspension... better body style, better look... better motor... better rear end... better wheels.... better cab... better door handles...

better creature comfort for the driver and passenger...

better memories.

i wonder where kenny sexy is right now... is there a way to track down a car by vin number? and if so - maybe i can buy him back cheap... and sell this hunk of **** i'm drivin - **** god knows half the parts in kenny i ahve a lifetime warranty on anyway.. so its be buyin a truck with a half a warranty sorta.

unrealii

omg, and I thought I had bad luck with dealers.

Let it go man...trust me. My old ford was totalled 5 years ago. A month after the insurance company paid us for it, I decided I wanted it back. They had already auctioned it to a company in mexico which rebuilds cars. I wanted to go on a road trip for the longest time. :eek:

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hahaha lol