MJHSC400

The cadence unit will NOT pose the same problem as you are removing the primary source of distortion, the OE amp--- It's a 7v line driver rms @ .009% THD (not even CLOSE to audible and FAR cleaner than ANY amp at max output) -- how is that introducing distortion?? It's a good way to solve this problem--

By simply boosting the signal from the h/u you won't be amplifying distortion until you reach about 90% volume (head unit distortion, not line driver distortion) -

Again, again, again, get the stock sub amp out of the loop--

Audiocontrol is OF COURSE better than cadence-- BUT it will serve the purpose of driving the line level and won't introduce distortion-- The main key-

That phoenix gold line driver is PERFECT-- but whatever you do, get the stock sub amp out of the loop, it will distort at full volume before the head unit's preamp will--

The head unit, AGAIN, is actually pretty distortion free up until near 3 o clock-- which is where I have my gains set to be at max listening level--

The rule of thumb is to set your gains to be at full listening volume as the head unit's preamp nears (but never reaches) clipping -- or distortion--

So when you do it this way, the OE head unit will present no problem other than needing the signal boosted--

The PG line driver will work awesome-- for the price it's possibly better than the cadence--

But be careful knocking cadence stuff, as they've proven capable of building some very good products for the money--

I have their CVL's and they're well beyond anything Polk has on the market-- And better than many $400 range components--

MJHSC400

It's also worth mentioning that with a 6 band PEQ you can do a lot of fine tuning that the head unit greatly leaves to be desired--

Having this amt. of equalization ability is nice when you only have the 3 ***** on the stock deck that don't seem to be focused/centered on the best frequencies to me--

1997sc300

You are correct that they probably made a good speaker but to say that the quality of the product carries through their whole line up is a far stretch.

Polk in my opinion does not make a quality car audio product either. I was even hesitant to recommend the PG product but it looks like it will fit his needs nicely.

When I buy car audio stuff I usually buy top of the line stuff from years back. Seems that's the only way to get your money's worth.

MJHSC400

I do the same-- BUT-- I've also seen older cadence amps in action-- they made all the power they claimed-- and did it well--

They have actually made quite a few quality products over the years--

Polk's DB6500's are nice components btw-- they smoked the same price range Alpine Type X's by a long shot--

I run all MTX amps at the moment, from the older Thunder Series-- a 4200x 50x4 (really 70x4) and a 1500dx -- (1kw rms class d monoblock) -- The 4200x has s/n ratio of about 118db -- really high damping factors, and don't start clipping until you really start pushing them past the 70 per ch mark or a little more--

engin_ear

iTrader: (1)

Some incorrect info in this thread...I unfortunately can't spare the time to refute it all.
Here's a couple of points...

1) There isn't anything seriously wrong with using the stock amp thru an LLC and thru another amp to drive the woof. The trick that is played here is that once you remove the requirement that the stock amp drive the woofer directly, it no longer has to produce any significant current - and that allows it to then produce relatively CLEAN signals. It only has to drive the high impedances of the LLC or the 10kohm+ amp inputs.
That said, if you can remove all that crap, you're generally still better off.

2) An LLC should only have negative gain = cut. It should not amplify. The best LLC we know of is the AudiolinkII, which is completely passive, and so cannot amplify. The job of the LLC is to take higher speaker level signal and reduce it to line level. Note the reduce. There is no gain required.

3) If you have a subsonic filter filtering 20Hz and below, there is NOTHING wrong with that. It does not cause the signal to be "bad". The only thing that signal energy below 20Hz is going to give you is HEAT - in your amp, and in the voice coil of your woofer, which is exactly where you don't want it. It can also cause overexcursions of your woofer at a frequency you can't hear anyway.

4) You CAN'T blow a 15 inch speaker with a Walkman, it would be practically impossible. It cannot produce enough current (or even voltage) to do that. And that's the same reason that the sound distorts. And because you can't produce the current, you can't produce the heat. No blown speaker. Just a $-hitty sounding one.

5) There is nothing wrong with polyfill in your woofer enclosure. No need to remove it. It prevents standing waves and goofy interactions inside the woofer. Nevermind that slows down the waves theory, makes the box seem bigger stuff. There's more to it.

Jerry

MJHSC400

Wow-- 10kohm certainly does require less of the amp and would make the signal cleaner-- I didn't think about that--
One of the main reasons I wanted to eliminate the stock amp is reliability as well as quality-- I don't think the quality is there based on the fact that mine is dead and many others have died, as well as my stock 4ch amp is just plain weak and distorts pretty quickly-- so I based my quality assumption on those reasons-- I just don't think the stock amps are that great sq or reliability wise-- So if the sub amp did finally die, which isn't doubtful that it will, the whole setup would have to be re-done and low level/preamp outputs are generally cleaner even if the sub amp would be quite clean at 10kohms-- Stepping up the h/u preamp with a high quality line driver is certainly better than stepping signal through an oe amp AND a LLC -- It's always a rule to eliminate as many possibilities for signal degradation as possible-- So it would be even better just to get a new head unit like an AVN 5500 and call it a day--

I agree on the 20hz subsonic too-- my 2xs has one at 18db/octave -- it affects literally no booty shaking music I own-- even Lil Jon Gettin Low plays as it should --

I think it is meant to filter infrasonic information in mastering to prevent it from being amplified and destroying your subs-- If you had enough power to do it it could certainly happen--

engin_ear

iTrader: (1)

Correct, but generally infrasonics from the source material are filtered out by AC coupling capacitors that are used to couple the amplifier stages together, so that stuff never gets all the way through. The infrasonic stuff can also squeak in from intermodulation harmonics, or distortion components from poor components or amplifier stages, incomplete or incorrect grounding, mismatch of components, etc., so it is best to filter that out. You can get really high near-DC voltages that the signal rides on, and you would never hear that, but it's like connecting your subwoofer directly to your battery. Nearly direct current right thru your voice coils. Fun if you like fires. It also pushes the woofer too far in either direction, so that you run out of excursion room to reproduce the actual music, and you wind up with distortion instead.

labtec

thanks for all the input guys. i've been trying to tweek my setup day by day and it doesn't sound too bad now. MJ, i still haven't had time to remove the stock sub but I'm expecting that it will make a huge diffrence. I think I'm going to continue to use my LOC for a little longer, at least till I get my stock sub out (I'll turn down the gain's on it and see if it helps). Overall I'm pretty satisified with the setup. I carpeted the box today and installed the terminal cup! I'll have pictures soon after I mount the amp.

One thing that I now find annoying is that when the bass hits hard, the Nak CD changer skips like no tommrow.

bsmith203

iTrader: (1)

No one has mentioned the most important thing about your system, The woofer is new and needs at least twenty hours of listing time before you get optimal performance. Why? because the suspension on the woofer spider still has to break in for optimal xmax. Just remove your stock sub and dynamat the rear deck. Big bass is coming!

MJHSC400

I want an update-- How's it goin??

Seize

Yeah, I second that....I'd like to hear what your impressions are of the TC T2K in a sealed enclosure is like.

labtec

hey.

Its been a long time....

The setup is working out nicely. Thanks for all your help. It kicks well (and I still haven't removed my stock sub...maybe after the holidays).

My next project is to change the front speakers. They start to crackly when I turn it up.