Amp question (Soundstream Class A 10.2)

Since there seem to be quite a few audiophiles on here, I forgot I had this amp, but it's broken, won't turn on and I think I might get it professionally repaired if I can't fix it.

http://www.soundstream.com/manuals/AMP/rubican/ca52102/RubCA52102.pdf




it's a Soundstream Class A 10.2 reference Rubicon amplifier from the late 90's.

something I don't understand: how the hell can this amp possibly be Class A amplification with MOFFSETT amplification as a car SUBWOOFER AMP?? I think they are lying and full of shit.


Also, how does it go from 25 watts RMS per channel @ 4ohms which is somehow 200 watts bridged at the same impedance? how the hell is that possible; do they not know how Ohms law works?? Apparently this amp defies physics?? stupid. Also, if it's a quarter ohm load, how is it not 2000 watts per channel stereo, or 4000 watts in 1/2 ohm bridged? Does ohms law really not apply to this amp at all?

Then again, with class A amp, it would literally start melting the aluminum heat sink at a 1/2 ohm load bridged, so there's no way these specs are real, or ohms law does not apply to this amplifier somehow?

then it goes on to say 500 watts @ 2 ohm bridged, when it pushes 25 watts at 4 ohms? okay..then it says 1000 watts RMS @ 1 ohm bridged with 0.1% THD and about 100db signal to noise ratio class A amplification?? are you kidding me ?!? are they just putting down random numbers, wtf? oh, heres the best part, they claim to be rock stable at a QUARTER OHM, with class A solid state, from the 90s?? This is a joke right??

Then after reading on on the internet, stupid ghetto rap bass kids are claiming that Soundstream UNDER RATED THE SPECS??

Iv'e read that the THD is closer to 0.02% THD and the signal to noise ratio is actually 109db and it can push over 1200 watts RMS at a quarter ohm.

I will admit, it came with an 80 amp maxifuse, but there's no way those specs are real, I seriously almost refuse to believe it..

I got this amp for free because my step dad used to be in the repo towing business, and it has it's perks. It worked for a while, but I had it driving two garbage rockford fosgate drivers in a really bad bandpass box for a while, powered by a power supply hooked up to the sub out from my old NAD T751 receiver before it stopped working.



I'll admit I thought it was rather loud for 25 watts RMS per channel, and those drivers were such garbage I would have blown them in an instant plus I didn't have 500 watts of power to give them via power supply at the time bridged in a 2 ohm load, and I probably didn't even know enough about audio to think to even do that at the time either.


Oh yeah and if it's class A amplification, I'm only getting half the power right? so with efficiency loss, I'm getting only 500 watts @ 1/4 ohm max power possible, and a 500 watt space heater in the back of my car is complementary? lolol



ANYWAY... I'm asking..are the specs on this thing bullshit? or is this thing actually worth getting professionally repaired?


Also, if it DOES work at the specs they claim, how would it make a TC sounds LMS Ultra 5400 at 1 ohm from bridging the voice coil, they claim will be 1000 watts RMS @ 0.1% THD (I don't believe it)

but is anyone familiar with that driver?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=293-666




It's an 84 pound driver, lol. but my question is, would I get over 100db @ 20Hz using my amp bridged at 1ohm pushing 1000 watts (or 500, I don't even know..) with under 1% THD? and could I hit as low as 10Hz using as much of the Rivvy trunk as I can?

I ended up deciding I want this thing repaired either way. I'll power some side speakers with it if the specs are bullshit, I'll admit, it sounds damn clean on hifi speakers (I've tested some PSB monitors on it when it worked with a car battery)







I spend a few hours re finishing the aluminum casing and heatsink. the dumbass that owned it before me spray painted it and it was crusty black looking like in the before pic.


it has a micro brush finish polished out to a semi mirror finish, so smudges and microscratches won't show up as bad. You guys think the finish came out nice? I used Kyrlon fusion on the white grimy looking plastic terminal housings, and I might make the trim panels satin black to make a nice two tone paint job on this thing.


What do you guys think? I kinda like how it was spray painted before, making the black in between the heatsink fins contrast nicely. and my mom is a professional jeweler; she said she'd stamp in the labels which were no longer there and the model name. and I might wax in an awesome logo as well

beauts! I'll take it! just send it my way Express!

Lol, That leads me to believe it might be worth it to repair this amplifier?

Apparently it retailed for $700 back in the late 90's which is even more today, inflation calculator tells me $962.63

But uhh, are these specs real or not? and did Soundstream actually under rate this amp?


And, would it drive the LMS ultra 5400 fine or no?

Also how much would it cost to get it repaired?

First understand the difference between Class A, B, and Class AB amplification.

The output device used for different classes can be any type: tube, transistor, MOSFET, whatever. Doesn't matter. The class is determined by how the devices are employed.

Class A - the output devices are always on. They use high bias, or idle current, so there's lots of heat and it's not very efficient. This limits power output.

Class B - uses lower bias current, the output devices are only on half the time. This is more efficient, and runs cooler for better power, but more distortion.

Class AB - a hybrid, works like Class B, except the bias current is increased like class A for less distortion. Still pretty efficient, and sounds good. Most SQ amps are Class AB.

The Soundstream "Class A" amps really aren't true Class A (they're AB), but they use a very high bias current, which makes them work more like Class A. All the SS Reference amps, including the Class A and Rubicon, were extremely good SQ amps.

But the 15.2 and 10.2 were designed as capable sub amps, specialized for low impedance loads, indicating they were meant for subwoofer duty. They were actually cheater amps, intentionally designed with underrated 4-ohm power specs. The 80 amp fuse reveals just how much power could be made.

Soundstream hired some audio tech wizards back in the day, who came up with some crazy ideas, resulting in some of the best power amps money could buy, and some weird ones like the "Little Wonder", which didn't even have a power spec. But the higher idle currents made them run hotter, and the circuit boards on some models were not the best. The early-mid 90s SS amps were pretty good to not so good, to very good, depending on which model and when they were made. I think the Rubicons were pretty reliable.

The reason for the power ratings - to keep the amp a cheater, the 4-ohm rating was designed to be low - 25x2, so an SPL competitor could use two and stay in the 100W class. Dropping the load, 2000W RMS could be created from a "100W system".

Bridging these amps was rated into 8 ohms, again so that more watts could be extracted under low impedance loads. The architecture permitted a 4X power increase whenever the load was divided in half. Although stable, the 1/4 ohm stereo and 1/2 bridged modes are power limited, probably due to heat concerns.

I used to do stereo installs back in the late 80's early 90's when I was in high school,
we never touched soundstream! I think now you can find great amps at 1/4 the price
of the old school tech. and their more efficient! Plus you cant actually go by the Watts
at RMS or Peak! all manufactures fudge these numbers to a degree. the most accurate
that I have found are Kenwood, Polk Audio, Kicker, and Alpine. and I'm not saying that there
100% on the numbers! they just list a close approximation to what you may experience
in your car. when they bench mark these they have them hooked up to scanners and scopes
that they can use to adjust the output. and when running an sub, always use an class D!
they give the most power at the coolest temp and with little distortion at the low end frequency
I think you could use that amp for your other speakers and be happier with the sound!
class A amps are very clear of distortion but are prone to over heating. the class A/B amps
are just as good but do not heat up as much... fewer blown fuses. I hope you find this helpfull

Damn Aaron you beat me to it and sounded so much more tech savvy than I did

Okay, I guess it is as good as they say :o


I was really wondering how the power load didn't increase at a 1/4 ohm load, and I know pretty much how amp classes work, but some people were saying online that it was a class A amp and others were saying it wasn't. My studio monitors use class AB amplification, which is nice, My Velodybe ULD 18 is a class B amp that pushes 400 wattts RMS @ 10 ohms with 0.5% THD. my Alpine monoblock amp is a class D amp pushing only 400 watts RMS @ 2ohms with 1% THD and like an 88db signal to noise ratio,

I really wonder how good that amp will sound if I get it fixed with 0.1% THD (some say lower) and 100db signal to noise ratio (some say higher) at 1ohms or 2 ohms bridged :3


Oh, and Aaron, do you believe it's worth fixing this amp, or paying someone else to? I don't want stupid amounts of power as much as I want true sound quality, and I hate my subwoofer setup currently. it sounds like garbage to me, even if most of my friends think it's amazing.




So, Gmann, I can tell you for a fact, a new cheap amp will not satisfy my needs whatsoever


by the way, does it actually push over 1000 watts into the woofer taking efficiency into account? And, what would the max output realistically be like at 1 ohm bridged, what the specs say, or more, like others say?

seriously though, if I can push over 100db @ 20 Hz with a TC sounds LMS ultra 5400 using this amp with under 1% THD, and hit 10Hz flat in my trunk somehow, I will literally pay someone to repair this amp, and save up a grand for that driver, which is the only high end sub driver I'd ever pay big money on

I would pay to have it repaired. The amp is a beast. The 1000W is questionable. I would shoot for the 1 ohm bridged output if you can, or 500x2 at 1/2 ohm to get max power from it. Usually you'd need to wire multiple subs for this arrangement. You won't get much power from the amp driving 4 ohm loads.

If we assume the amp is 100% efficient (ain't gonna happen), the 80 amp fuse will allow 960W at 12V. The power supply is unregulated, so it makes more power with the engine running. At 15V and 100% efficiency, 1200W are possible. But the amp isn't 100% efficient - probably 85% at best, which is probably where they got 1000W. Disappointing, but I don't think that's true RMS. I just don't see how they can get 2000W peak through an 80 amp fuse.

Still, it's a decent amp that makes a good amount of power. I'd fix it and use it just for the vintage effect. Use cooling fans to keep air running through and around the amp. If you need a few, I have dozens of brand new 12V fans I'd sell at a good price.

I agree with glenn that newer, more practical class D options now exist. If you really want the most power for your dollar, that's the best route to take, and you can even have it at 4 or 2 ohms. But the SS Rubicon is just too cool. It's a classic. It'll be plenty loud, and if for some reason it's not, buy a twin and use both to power your sub wall!

Corey, I said cheep as in less expensive than the old school amps were. an $500 new amp is
about equivalent to a late 80s $1000 amp and is more technologically advanced.
I didn't mean you should buy an $30 amp at a wholesale website...
lets not get our wires crossed LOL

gmann3001 wrote:

Corey, I said cheep as in less expensive than the old school amps were. an $500 new amp is
about equivalent to a late 80s $1000 amp and is more technologically advanced.
I didn't mean you should buy an $30 amp at a wholesale website...
lets not get our wires crossed LOL

True, but even a good sound quality amp pushing 800 watts would cost a ridiculous amount of money compared to repairing mine, I believe, also The amp I have is here:

http://www.crutchfield.com/S-u5oqdDkhirG/p_500MRPM450/Alpine-MRP-M450.html#details-tab

I don't like the sound of monoblock class D, maybe it's just me, but it doesn't sound anywhere near as clean as my Velodyne ULD 18 servo controller class B 400 watt amp did when it worked.

And, These specs don't add up to me at all, but I see a lot of people vouching for this particular amplifier.

I really want to know how this amp would drive the LMS ultra 5400 though, I think around a thousand watts on a 1 ohm load into it's voice coils should be plenty loud, lol. I'm not trying to win db dragraces with this setup as much as having the ultimate quality bass, and Class AB amplification at at least around a thousand watts on a 1 ohm load bridged on a woofer that rapes my Velodyne which is the best sub Iv'e ever heard yet.

So my next question is, would it even be worth buying the LMS ultra using this amp which is a DVC 2+2 ohm VC sub that can be 1 ohm bridged? Or would I be better off buying a different driver setup, like two really efficient 500 watt drivers?

There's no reason not to use a Class D amp for subwoofer duty. The slightly higher distortion isn't audible in the lower frequencies. 1% THD isn't really audible even in the midrange and treble bands, where it counts. For bass duty, you're kidding yourself if you think Class D isn't good enough.

Here's a question: whats the impedance of the Velo sub? Assuming it's 4 ohms, the Alpine amp puts out 220W RMS. If the Velo amp is rated 400W, no wonder it sounds better. The Alpine was probably clipping trying to drive the power hungry Velodyne sub.

Speaker load is a big concern when using the SS 10.2. If you don't run at least 4 subs, you won't be seeing any real power from the amp. Getting down to 1ohm is tricky unless you are using low impedance, DVC drivers.

AA wrote:

There's no reason not to use a Class D amp for subwoofer duty. The slightly higher distortion isn't audible in the lower frequencies. 1% THD isn't really audible even in the midrange and treble bands, where it counts. For bass duty, you're kidding yourself if you think Class D isn't good enough.

Here's a question: whats the impedance of the Velo sub? Assuming it's 4 ohms, the Alpine amp puts out 220W RMS. If the Velo amp is rated 400W, no wonder it sounds better. The Alpine was probably clipping trying to drive the power hungry Velodyne sub.

Speaker load is a big concern when using the SS 10.2. If you don't run at least 4 subs, you won't be seeing any real power from the amp. Getting down to 1ohm is tricky unless you are using low impedance, DVC drivers.

Actually, the Velodyne driver is about 10 ohms, but I fooled the Velodyne servo controller to power my Alpine sub setup wired in 8 ohm paralell and it sounded a good bit cleaner than on the Alpine monoblock, hit harder too.

Oh, and Iv'e built my own home made amplifier a while ago that is 15 watts RMS per channel @ 4 ohms, and I bridged it to the Velodyne woofer for a while, and it hit really low and deep, sounded really clean, but wasn't very loud, so I think the alpine amp wouldn't be clipping the driver super easily. The Velodyne driver is retardedly efficient, but I may try this theory one day.

The Alpine will not sound good driving 10 ohms. After about 80 W you're going into clipping. If the Velodyne amp is making 400 W into 10 ohms, you're probably pushing 450 into the 8 ohm load. If the amp will drive it, its going to sound great. My point is, the Alpine is at a severe disadvantage in your tests. If you wire it to use its power, it will sound more like the class B.

You're right to a point, but I wan't blasting it at full volume by any means when I had it at an 8 ohm load into the Velodyne amp, and the car is a different enviroment, with random things to vibrate, since I didn't sound treat my buick, and Signal to noise ratio is MUCH lower on the Alpine. The bass sounded tighter, and less muddy, and more accurate on rock and acoustic music, or music like Apoctlyptica though on the Velo amp. I'm not trying to be a snob as much as just trying to get the most accurate bass possible. I'm sort of interested in HAwkings bass control because it's said to optimize linear excursion to SPL and lower xmax distortion as low as possible while providing the most efficient sound, helping eliminate distortion, making a more accurate sound, and keeps the driver from blowing as much, but I haven't read a lot about it.


http://xform.audiogoshop.com/index.php?main_page=product_info&products_id=12208&offer_id=B004TMFMMG

http://www.halfpricecaraudio.com/RE-Audio-SX18-D2-18-Dual-2-Ohm-SX-Series-Car-Stereo-Sub-Subwoofer-SXX18-D2-SX18D2-SXX18D2-REA-SX18-D2.htm

Same woofer, but the $150 price seems like it might be a fake or a rip off. I know nothing about this driver but RE audio claims almost 93db efficiency out of this driver on their spec sheet on their site. would the Soundstream sound good on that driver in a 6-8 cu ft box sealed in the Rivvy trunk? (I don't need trunk space, because I won't be using the rivvy to be a grocery getter, and am willing to use the entire trunkspace, vented out my fender, if it will sound clean.


But, I just want to know if the RE audio driver will be capable of over 100db @ 20Hz with under 1% THD, which is less capable than my Velodyne driver @ 400 watts RMS, and if it's a solid, reliable driver, because I really wouldn't mind setting that up in my buick for a while until I could afford the TC sounds driver

If I read that right, you're comparing a home theater sub amp powering 2 subs inside of a car to the Alpine + Velodyne combo. Was the Velodyne sub tested in the car too, or in the house?

The hawking bass control is just fancy jargon for an ultra-sonic filter. You don't want this for SQ in sealed boxes (ULF is critical for accurate transients [Qtc] in acoustic suspension designs). The purpose of the hawking control is to minimize excursion in vented enclosures, so you can produce higher SPL above the box's Fb point. In other words, it protects the mechanical limits of the driver so you can exercise the thermal limits of the driver. It is intended for increased SPL, not improved SQ.

I wouldn't assume the lower price is a rip off, not good to be on guard. Lots of audio gear is priced down to "street price". Try calling the vendor if you're suspicious. You'll be able to tell if it's a shady operation. Shop around and see if other vendors can come close to the price. If they can't, it might be an advertising error.

Slap the SX18 in a 6-8 cu ft sealed box, wire coils in parallel, fix the SS amp and bridge it. If done correctly, you shouldn't have any problem hitting 100 dB@20Hz. Will probably see 120dB easily, and F3 point in-car could be ~10-15Hz depending on available power and quality of installation.

I wouldn't get hung up on the 1% THD thing. I can promise you - if you listened to 100dB@20Hz@1%THD vs. 100dB@20Hz@10%THD, it would be very difficult or impossible to discern the two. Fact is, most subwoofers are bumping out 15-20% distortion, and listeners are okay, because it sounds very good to the ear. The lower the octave, the less sensitive we are to THD. Any sub creating max SPL at under 10% is considered the "linear" or "low-distortion" type.

If you want a really low distortion sub, look into the underhung coil types from PPI and AudioMobile about 10-15 years back.

Just get the SS 10.2 fixed I've owned ALOT of amps and still do. There is absolutely nothing wrong with a good condition old school SS amp. That was back when they were still built in the U.S.A. You won't be disappointed in it's performance. As for cost to fix it shouldn't be that bad, I think I was quoted just a shade over $220 to repair 1 of my RF Power 1100a2 amps plus shipping. That amp retailed around $1500+ CAN brand new back then. They are better than the new knock offs of today, most companies have contracted manufacturing out to the Chinese.

Old school amps, grunge, and the internet are about the only good things to come out of the '90s. I have a couple of these puppies in my Olds. Both are BRIDGED, each powering left and right channel components. Rockford's spec sheet for these reported 105W RMS x 1 into 4 ohms.



My Riv's bass amp, one of the first Class D amps, if not THE first:



Powering a single GEN1 Kicker 8" Solobaric L7:



If you are wondering how loud the 8" Solo L7s can get, the Stillwater team put two of them in an S10 pick-up, supplied 1200W RMS to EACH one, and hit 155 dB - this was back in the late '90s, when the SPL record was around 165 dB.

The 8" L7 also makes a nice SQ sub in a 1.75 cu ft sealed box supplied with 200W RMS. Because it's built to take abuse, it will last forever in my system.

I never put the velodyne sub in the car, that would be silly, I just wanted to see how clean the same drivers would sound with a class B amp at the time, and wired the subs to 8 ohms into the velodyne amp, which was nearly the same impedance, which wouldn't fry anything. ended up sounded a good bit cleaner than the monoblock from my experience, but there are too many variables to really definitively say how much cleaner it was.


Hmm, I might end up buying that RE sub driver to get an 18" setup in the somewhat near future, coupled with the soundstream amp, fixed up. I guess the reason I'm hung up on THD so much, is because almost every car sub Iv'e ever heard from my friend's setups sounds like garbage to me, and even in my Alpine dual 12" setup, I can hear the sub muddy at lower than 30Hz, which I really don't like. I mean even these bad alpines are better than any of my friend's setups, and my amp is 1% THD, it's clean for the most part, but not as accdurate as I'd like it to be, plus on rock, and other music other than electronic, is where it really gets sloppy, and every review says how tight and clean the bass is from such a cheap driver.

Maybe I got spoiled by the Velodyne, but I'm just hoping that the soundstream+ RE woofer will sound just as good right now, but $150 seems too good to be true for such a driver. if anyhing, I might use the RE woofer and put it in my 5.7 cu ft Velodyne box and buy a Dayton 1000 watt plate amp, and keep the Velodyne parts in a box somewhere until I can find someone to retore the servo controller, so a newer amp won't burn the coil on my Velodyne driver. It's an outstandly well built box actually, the sub weighs like 105 pounds, with maybe a 30 pound driver lol.

So basically, that would be an incredible performance to price ratio if the RE woofer worked well with the soundstream amp fixed up. I'd love to get 120db out of it, but that might be stretching it a little, then again I won't really ever be pushing it that loud other than maybe scaring the crap out of a friend, lol.

Edit:

by the way, that astounds me that two little 8" square woofers pushed 155 db, and take 1200 watts RMS per driver, and still be a good SQ sub

One of the biggest variables with regard to frequency response, especially in the bass range, is the acoustic environment. You can put the exact same system in a car, then move to a living room, then to outside, and it will sound so drastically different, you could get more consistent results comparing two completely different amp/sub/head unit systems if all are swapped in the same car. Even changing the location and firing direction of the sub enclosure can produce huge variances in output and response.

Cars offer "cabin gain", or LF reinforcement that basically builds up the frequency response down to the resonant frequency of the air space, then drops off, but still offers big gains in the subsonic region. Bigger cars tend to peak around 40-50Hz, smaller compacts and trucks around 60-80Hz. For this reason, a true SQ system does not have a flat driver response. You actually want a natural 12dB/oct downward slope, because the cabin gain will equalize it, resulting in ruler flat bass.

Put the same sub with sealed box and 12dB/oct gain in a living room, it will sound good, but wont go as low. Take it outside and you'll wonder where all the bass went. This is why vented boxes are more common in home audio, and absolutely required for outdoor systems. It's also why very powerful bass in home audio requires a big sub, and outdoor events require a trailer of big subs.

So there's no fair way to compare Amp A + Sub B to Amp B + Sub A, because they're not operating in similar environments, and are loaded in completely different ways.

Regarding distortion, keep in mind that electronic equipment produces so little THD that we can't really notice it until clipping is reached, and we know what that sounds like. But what most don't know is that speakers create FAR MORE distortion than amps or head units, because good ones are more linear in operation, and bad one aren't. Non-linear = distortion. Speakers aren't rated for distortion, and that's interesting because I think it would totally change the way equipment is purchased and how systems are designed. Speakers produce massive amounts of distortion: 1-2% is normal for a "good" driver in the mid/high range. 5% is audible in that range, but for bass our ears tolerate much more. 10% is good, and 15-20% acceptable. When you hear the break-up at 30Hz, it's a combination of non-linear cone movement and amplifier clipping from reaching the power limits. That 1% distortion spec is meaningless at that point.

Good news about the 18" driver is super linear behavior, because the cone doesn't need to move much to get loud. The result is efficient, super clean, low distortion bass, and if needed, loud SPL. The reason it can get loud is because the larger 18" can actually use the power from the amp and still operate in a linear fashion. And because it's efficient, it won't take as much to get loud.

$150 does seem too good. Look around an buy the next highest price you can find. Look for deals on used subs in good shape online and locally. With the 18 running 1 ohm mono to the SS amp, 120 dB will be easy, and as you'll see really isn't at all that loud in the lowest octaves.

Awesome, second lowest price is over $300, which is weird

and by the way:

http://velodyne.com/pdf/uld/uld-15-18_manual.pdf

my goal was to basically reproduce at least as good as my beloved, now broken subwoofer, if I can get anywhere near those specs, I'd be happy with sound quality, but 100+ db from a quarter inch of excursion isn't easy :/

I see your manual has a few words on speaker distortion.

Keep in mind that you will easily exceed the Velodyne's SPL specs in a car because of cabin gain. It's not uncommon for an 18" sub with adequate power to push 135-140dB, even into the very low notes. 125dB of distortion-free 20-30Hz bass is kind of unreal. It feels more like the air conditioning is on full blast, modulating to the music.

Hope your plan works out. Looking forward to seeing pics and hearing your report.

It won't immediately happen, but I'm definitely going to at least get some kind of nice setup like that some time in the next few months if I can help it.

I'm guessing porting the air out of the fender is the best bet? and how many cu ft is in the rivvy trunk? max reccomended ported box size is 8 cu ft, and it doesn't seem like they want the driver to be in a sealed box, so I'd have to make some models of speaker box designs. I'm thinking in dabbling with fibreglass possibly, but box dimensions are harder to figure out that way. Either way, it seems like A fun way to finish off my sound system mostly for good in the rivvy, and I can put the Alpines in my Eclipse, which is a tiny 1g DSM hatchback which weighs 2500 pounds, so it's going to be pretty loud


Speaking of Fiberglass, I can't get any kind of vinyl paint to stick to my door panels. I'm thinking about paying someone to do a vacuum mold of my door panels with extra speaker holes in fiberglass. any idea on how much that would cost?

Oh, and I can't wait to have 125db of distortion free subsonic bass, I love a lot of electronic music, and some rap/hip hop as well as rock, metal, and other genres, so the musical accuracy will be amazing as well.

I would never go vented with an 18" in a car, but up to you. Sealed boxes are easy, less risk of messing up, and the roll off is very smooth. Shoot for a Qtc of around .50 if you are wanting to tap into 10Hz territory, .70 if you want a little more boom and SPL. More on Qtc and transient response here: http://www.gmforum.com/showthread.php?t=293590

I tuned for .50 Qtc and love the ultra-quick beats and very low extension. This is known as "purist", "A+" or "SQ" box. The biggest problem with low Qtc is you will reach your mechanical limits sooner than thermal, meaning the sub can be damaged if you don't watch how hard you're driving it and set gains accordingly. The sub's (thermal) power spec no longer applies in such a large box, but it will sound awesome. Maybe the Hawking control can help here.

If you want to be able to dump full amp power into the sub, you must use higher Qtc of 1.0 to 1.5. Bass will be much more boomy, not as flat, but will get ridiculously loud around 50-60Hz.

AA wrote:

I would never go vented with an 18" in a car, but up to you. Sealed boxes are easy, less risk of messing up, and the roll off is very smooth. Shoot for a Qtc of around .50 if you are wanting to tap into 10Hz territory, .70 if you want a little more boom and SPL. More on Qtc and transient response here: http://www.gmforum.com/showthread.php?t=293590

I tuned for .50 Qtc and love the ultra-quick beats and very low extension. This is known as "purist", "A+" or "SQ" box. The biggest problem with low Qtc is you will reach your mechanical limits sooner than thermal, meaning the sub can be damaged if you don't watch how hard you're driving it and set gains accordingly. The sub's (thermal) power spec no longer applies in such a large box, but it will sound awesome. Maybe the Hawking control can help here.

If you want to be able to dump full amp power into the sub, you must use higher Qtc of 1.0 to 1.5. Bass will be much more boomy, not as flat, but will get ridiculously loud around 50-60Hz.

I didn't want to lol, but the RE website says that driver is designed for a ported box, but I'd have to play with speaker design software yo see enclosure size for a sealed box and if it can even work for that driver. I'm not sure without typing the numbers in first.

But people seem to be really uptight about keeping it the way the manufacture wanted