hank_rearden1

Hey guys,

I have been lurking around here since buying my first Corvette two years ago. I picked up a wealth of information and enhanced further my enthusiasm for my vette and the platform overall.

I have benefited from lots of great tips.

So finally, here is my contribution back to this great forum. I summoned up some more courage and cash and decided to move forward and undertake an overhaul of the Bose sound system and document the processes at the same time. There were a lot of lessons learned in this project (for me, at least). I hope by sharing this install, others will get some tips too.

But first, here is some back ground on the car.



It's a 2001 Coupe with Z51 Package. It has many Z06 performance mods. The mechanical mods were performed by the original owner with the intent to get new C6 Z06 performance from the vehicle. He was successful. The car is tuned with HP Tuner. Most recent dyno (on a WinDyn) has it at 424 RWHP.
Mods (Engine components from Texas-Speed and Performance):
Clutch (LS7/Z06 Clutch)
Integrated Kooks Titanium Long Tube Headers / Kooks Cats / Z06 Mufflers
HP Tuner "handles" all of the emissions codes
Wideband Fuel Sensors / Active Lean / Rich Monitoring
Stage 1 LS6 Cylinder Heads (Competition Valve Job)
Torquer V2 Camshaft (113 LSA)
- Comp 918 Valve Springs
- Chrome molly Pushrods
- Cadillac Racing Lifters
- LS2 Timing Chain
ARP Rod Bolts
ARP Crank Bolt
Clevite Rod Bearings
LS6 High Flow Oil Pump
SLP/Powerbond Underdrive Pulley
180* Thermostat
Halltech Cold Air Intake/Filter
Oil Pressure Sender Relocation / Replacement Mod.
Motorola T606 Blue Tooth Interface.

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I finally got fed up with the factory Bose system performance... specially since switching from my Windows Pocket PC pda phone (which had a very good Core Player media application and equalizer which compensated for many of the Bose system shortfalls) to my new Android phone, which is a much better phone and interface but has a crappy music player. I supposed I could have retained the Windows PC phone and used it just for music in the Vette... but then I really want just one interface for communication and media/music.

After researching on Crutchfield and on this forum, I decided that the answer was to retain the factory head unit (minimize the need to mod the dash) and the Motorola T606 Blue Tooth which works really well. I also already have very good GPS and video capability on phone so I wasn't really interested in getting a video touch screen. My main objective was to greatly improve sound quality.

The best sound processor I found (to replace the Bose Sound Processor) is the Alpine H660. It has a 512 band dynamic eq; 6 channel crossover; and 6 channel time delay. It would become the brains of my new system.

The muscle of the system would be the Alpine PDX5 -- its a 4 X 75 watt + 1 X 300 watt amp. It is small and plenty power enough for the cabin the size of the vette and desired speaker set. I like the idea of not needing to install multiple amps in the car and the PDX from what I read delivers very clean stable power.

The Bose speakers would all go-- replaced by:

(2) 8" Kicker CRV Woofers in the doors
(2) 3.5" JL High Range 2-way Speakers (originally were going to go in the back directly behind seats but instead decided to mount in the doors, replacing the factory twiddlers)
(2) 6.5" JL Mid Range 2 way Speakers-- behind seats (factory location)
(1) 10" JL Stealth Box Sub Woofer.

Also, I picked up two cases (a total of 20 2X3' sheets) of black dynomat.

The total cost of this project was (roughly) $2600 (does not include Motorola T606 ($450) which was a prior mod).

Sound Processor: $500 (Crutchfield)
Amp: $500 (Crutchfield)
Kicker Speakers: $350 (Crutchfield)
JL 3.5 and 6.5: $500 (Crutchfield)
JL Stealth Box: $450 (Crutchfield)
Dynomat: $300 (Local car audio install shop -- great deal)
Miscellaneous supplies, cabling, wire, etc: $250 (Crutchfield / Home Depot)

Time to Complete: 3 weekends including Friday PMs.

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So let’s get to where the metal hits the meat...



The brown truck of happiness swung by mid-week and dropped off everything I ordered from Crutchfield except for the Stealth Box... that would take two weeks since that required custom fabrication for the vette.




I starting reading all of the specifications and manuals for the stuff I bought leading up the weekend -- I also went through read the Audio FAQ on this forum and planned out / diagramed my install referencing my shop manual. I felt pretty good going into this that I had a clear way forward.



From a design standpoint, I started at the speakers and worked my way backwards -- the idea was to wire the Kickers in parallel and the JLs in series. The Kickers (dual coils) have an operational range of between 50W and 200W while the JLs are 25W to 100W. Thus each Kicker would have its own 75W channel (cranked all the way up) and the JLs would be wired up so the each pair of 3.5 and 6.5 speaker would share one 75W channel (cranked up about 75% of max). The Kickers would be on channel 3 and 4 while the JLs would be on 1 and 2 per the diagram (however, I ending up wiring the Kickers on 1 and 2 and JLs on 3 and 4 to match the H660 front / rear output designation numbers).

I proceeded to take the car apart...and install the dynomat wherever I could...















I noticed that one of the bases that holds the pin / clips on the door panel had broken... I used PVC pipe compound epoxy to glue it back and it worked like a champ!



I also dynomatted under the hood…



… behind the seats, mid-panels, and in the rear hatches.



With the dynomat installed, I started to work on the speakers. First, I had to figure out where and how I would mount the 3.5 JLs. My initial idea was to build small stand-alone enclosures using the hard foam packing materials that with the kickers shipped with and some masionite board.







In this next pic you can see where I positioned the speakers originally. I also mounted the 2 X 4s (which is where the Amp and H660 would be secured) using heavy duty two sided carpet tape and 3M tape. I did not use any other adhesive or liquid nails… the 2X4s seemed very sturdy and secure just with the tape and also I figured that once the Amp and H660 are screwed into the wood through the carpet, there would be little chance of movement. If I am wrong, I can also secure it later with the adhesive.

I used the carpet tape and 3M tape for the 3.5” speakers too. Also, note that I actually did this step before attaching the dynomat in the hatch area since I was not sure that this speaker location would work out. Also, there was nothing really special about mounting the 6.5” JLs. Those dropped right in.

Oh and by the way. You’ll probably notice the R30 insulation. In a prior mod, I jammed R30 everywhere I could inside the car. It did quiet down the road noise quite a bit but at the same time I found that I always had this fiberglass dust that would accumulate on the dash. One objective in this install was to get rid of most of this stuff, replacing it with the dynomat.

Along the center drive channel, I had previously used heat shielded water heater insulation to keep the heat from seeping into the car. It worked fine. I am keeping that.



Next, I worked on installing the Kickers in the doors. I was concerned that the Kickers would be too heavy to secure directly in the fiberglass so I tried to squeeze them into the Bose speaker mounts. They almost fit! In this picture you can see the small gaps caused by the pieces of plastic that stick out from the mount. These needed to be dremeled off.



Here is the speaker mounted flush in the factory mount after dremeling off the plastic pieces.





I then removed the crossovers from the mounts (from behind where the twiddlers used to be). I got the idea to cut out a hole from behind the crossover / twiddlers to create a sound vent. The Kickers have a lot of low mid / solid low range sound, I figured a vent would help expand the sound projection a few inches higher.

I filled the hole with a 5” length of 3” dia PVC, securing and sealing it with a combination of duct tape and weather stripping. It turns out this hole will come in handy later.



With the speakers installed and wired --- I sent all of door speaker wires through the driver’s side rocker panel to the amp location in the back. I followed the steps illustrated in the other FAQ posts on how to weave the wires through the grommets in the doors.

My plan was to run the amp power from the battery via the passenger side firewall grommet and via the passenger side rocker panel. The amp ground is connected the inside rear bolt of the passenger. I am using switched power from the passenger footwell to power the H660. The H660 has a switched power output that connects to Amp. So, I can get retained accessory power for the audio system with the engine turned off (with the key in the accessory position).

Nothing really revolutionary here… I just followed the steps in the other Audio FAQ posts and the H660 and PDX-5 instructions. A great tip I read in the FAQ posts was to lube up (I used vaseline) the amp power cable before pushing through the inside of the car to the battery compartment. I pushed it through until I was able to grab it with a pair of needle nose pliers (before it came all the way through the grommet) and then pull it the rest of the way out.

Here is the how I set up the power supply:



I connected the amp power cable to the available clamped connectors in the bottom left of the fuse relay box. In a prior install, I had already attached a battery tender connection here and works fine. I also smeared a couple dabs of dielectric grease on the eye ring.

You'll also notice that I used a small tupperwear container in place of the hard plastic fuse connector holder that came with the kit. The kit connector had a hard plastic base that holds the fuse and connects the cable / circuit. There is top half (lid) that screws on to seal it. It didn’t look very moisture tight to me… it did not have any o-rings and just look cheap. So instead, I grabbed a small Tupperware container, taped it up with electrical tape, drilled 0.5” inch holes on the sides and used that to hold connect the circuit / fuse. I kept the hard plastic base, I just now sits inside the container. The container sits on the battery. The lid seals it air tight.





With power up and speakers ready, I was now ready to test what I have done thus far… I was really interested in how the speakers would sound… especially since I was not sure about the location for the 3.5” JLs. I also wanted to make sure that kickers would not over resonate or cause vibrations that required more dampening. Finally, I wanted to make sure I had not screwed up the speaker wiring configuration and that H660 and PDX5 actually worked.



Continued on next post....

hank_rearden1

... continued from post 1...

First off… and this is very important because no where is it indicated, not in the quick install instructions nor the 70 page pdf manual – [it took a 2 hour phone call with Crutchfield to figure this out (Crutchfield customer service is OUTSTANDING – they also helped me verify that all the connections were correct; They were very patient with me and very professional – I will be a customer for life] --

YOU MUST RUN THE CONFIGURATION SET-UP ON THE H660 BEFORE ATTEMPTING TO PLAY MUSIC THROUGH THE SYSTEM AT FIRST POWER-UP.

It will not play music at first turn-on. I really wish this was more clearly stated in the manuals... I was baffled to point of nearly taking everything apart and starting over, fortunately I was able to talk to the guys at Crutchfield. The H660 needs the special frequency signal playback from the Alpine set-up CD (that comes with the H660) to initiate activation. You simply do not turn it on and hit play on your head unit and sound comes out of your system… it is designed to verify that signals and levels coming from a new set-up will not damage it, the amp, or the speakers. You should also run the set-up every time you change your system configuration / speakers.

I ran the H660 configuration and baseline set-up using the included Alpine CD. The CD has two tracks which the H660 uses to measure and baseline the acoustics of the car. It runs through every speaker channel twice testing low harmonics and high harmonics as well as sound reflection. After establishing the baseline, I used my Droid to directly connect into the H660 2Ch aux input. The sound overall was really good in terms volume, clarity, and tone but the sound imagery / space projection was not right. It was like sitting in a concert and the bass drums and bass were playing in front of you while the guitars and voices were behind you. The H660 tried to compensate by turning up the delay to max on the mid and high range JLs; I did not have enough high frequencies coming from the front of the car. I really needed to move the 3.5” JLs to the door locations. So here is what I did…



I resized the foam containers I made for the 3.5” JLs to fit inside the original twiddler location. I had to remove the Kicker to access the area but it worked fine. The JL’s fit nice and snug.



And the Kickers locked right back in, nice and tight.





I re-ran the H660 config and set-up using my Droid and the results were outstanding! This time the H660 evened out the delays, and adjusted the crossovers on the Kickers to low pass (versus high pass, previously) at about 100h so now I am getting rich midrange and hot bass tones out of the Kickers with sharp crisp highs coming from the 3.5s… the H660 set the crossovers for the JLs at HP 90h creating really great harmonics between the front and rear sound spectrums. Acoustic music sounds amazing, it’s like sitting on stage with 3 classical guitarist while my Iron Maiden concerts feel like I am right in the pit. All this, and I haven’t even installed the Stealth Box yet!



Now for the hard part. I went back to my schematics and revisited the rewiring plan to connect the head unit to the H660.



My first attempt entailed connecting the line outputs from the head unit to the H660 inputs. In this picture, I am showing the head unit outputs that go to the Bose sound processor. My thinking here was that I could complete by-pass the Bose system and just sent the direct signal to the H660.





However this did not work!

The H660 gave me an error – something about “weak or wrong signal”. I then tried to directly jump the line outputs to the line inputs on the back of the head unit (again to bypass the Bose processor) and connect the head unit speaker outputs to the H660 inputs.





Still didn’t work. I got the same the error on the H660. At this point, I finally deduced that the H660 needs to get a processed signal… that the Bose head unit really doesn’t do any processing at all. It is just a user interface that sends very weak raw data to the Bose Sound Processor and provides instructions on how much gain to send to the pre-amps and amps. While this set-up may work for connecting directly to an amp via a harness wiring set-up… it does not work when using the H660. This is a subtlety unique to installing this particular component. After thinking this through some more and then going back to the schematics, it now seems obvious albeit it didn’t before.



So I ended-up undoing the Bose by-pass and re-soldering them back to factory configuration and simply connected to the speakers line on connectors C(1) and C(2).



Note that on my install, I had to deal with the harness that connects my Motorola T605 to the GM harness. This was no problem; I just made my soldered connections at the GM harness because this is the last point of interface coming out of the head unit to what otherwise would be the Bose amp and speakers.

This worked! I tested and baselined the system, again, and got great sound. This time I ran my Droid through the Motorola T605 and head unit and results were very good. I cranked up the bass and treble on head unit and found that it actually added a decent amount of tone without distortion. I also noticed that H660 reduced the gains on the inputs by about half and added less bass on the eq – this means that when fine tuning the sound later, I would have a greater range of tone and volume to work with.

Next, I began to clean up my cabling and lay out the prep for closing everything up. I used some of the packing material to provide a soft / quiet base for sections of cabling. Even with the dynomat installed, I did not want to take a chance that vibrations would cause cables to rattle under the carpet. I also labeled all of my cables after disconnecting the H660 and PDX5.



I added some green sound proofing insulation wrap material that blew on to my property from a nearby construction site. We had some heavy winds the previous few days and there was a whole roll of this stuff in my backyard that had somehow blown in over my fence.



I also decided to retain a little R30 in the rear left and right storage compartments.



So far I have invested about two weekends and now I was just waiting for the Stealth Box. You can imagine the thoughts I was having… thinking about what other mods I could do while I waited given that the car was all taken apart. I thought about the taking out seats and adding some dynomate those areas; I thought about installing seat warmers; new seat padding; LED lighting. Alas, none of these ideas some seemed compelling given that they would all entail buying or waiting for more parts. Also, I am happy with my seats. What did occur to me however was that my HVAC unit lights were dim (dimmer than the radio). I had browsed through the solder fix in the FAQ and thought I could do the job.

Well unfortunately I was wrong. Even though I had a lot of soldering practice via this audio project, I still was not skilled or experienced enough to do the detail work required on the HVAC circuit board. I also failed to read through and understand the details in the FAQ thread, specifically about using the right type of soldering tools. Here are my results (go ahead and laugh):



This did not work. In fact, I made the problem worse. Here is what my HVAC unit looked like when I turn it on:



The HVAC still worked – it turned on and off but the lights were all hosed up.

Fortunately I found this guy: digital_dash_solutions@comcast.net 1-860-583-0629. I call him up and he sent me a rebuilt HVAC unit for $200 (incl $100 core fee). It arrived in two days. I mailed him back my old unit and credited the core fee back to me.



I put it back in the car and it works great, good as new. The light are bright, as bright as the radio.



Perfect timing. The very next day the Brown Truck of Happiness dropped of the Stealth Box.



The contents included the Stealth Box and the carpeted replacement cover, both custom designed and made to fit the large storage compartment of my vette, along with mounting hardware.


The cover is aluminum, very light but rigid and strong, and has a speaker mesh that matches the color of the interior. The surround is made of masionite material.



First, the instructions said to take the latches from the factory cover and swap them into the new Stealth cover.


Next, remove the latch locks from the car



Cut the sub-carpet / backing out of the install area.



Place the wax squares (that came with the unit) as instructed in the front corners of the storage compartment base / bottom.



Then, I screwed-in the bolts (provided) into the unit and placed the unit in its space… the bolt heads created marks on the wax to indicate where I needed to drill a 3/8 inch hole into the car.





The locations for the holes are about an inch away from where my pipes bend into the mufflers. I was very careful to drop the unit in straight and squarely; I wanted to a get precise marking for the hole locations. This was easier than I thought; the unit fits perfectly snug into the compartment. It even has the groves and lans which mate with the those in the rear compartment of the car.

In this next pic, I inserted the bolt (with the unit removed) to see how easy or hard it would be to access the location from underneath the car. I was very happy to learn that I did not need to raise the car.



I put the unit back in the compartment, being careful to line it up as I did before. Then I proceeded to screw in the bolts. I used some outdoor caulk on the washers to make sure moister would not penetrate the anchor points.



It took some patience to turn the bolt because my hands kept jamming up against the pipes.



With the tight design, plus dynomat, and bolts, the Stealth Box is solidly in place… doesn’t move at all! Make sure you wire it up before you bolt it in… I could not imagine trying to remove it afterwards.



Screw the cover latches back in… these also help secure the box. Here is a pic with the cover on top.



Now for the last stage… closing up. I worked from the rear of the car forward. I think the only nuance to this install versus others that I have seen in this forum is getting the carpet to align with the hard top anchor pegs. The 2x4s caused the carpet to hump a little.

First, I laid down the carpet and pulled it forward as tight as I could – I wanted it to reach as far forward as possible so that the carpet behind the seats could fold underneath. I cut holes / slits in the carpet for the cables as pictured below (I am really glad I labeled them!).



Here are the hardtop anchor pegs... you can see where the carpet no longer aligns.



While pulling the carpet to the sides as far as a possible, I cut about 1/8” of carpet where it covered the location anchor ring in order to allow the anchor ring to snap in --- I cut just a little carpet at a time until I was able to get the ring snapped in--- I was worried that the cutaway of carpet would look like a hole but it turned out okay, especially after installing the anchor itself.





Here it is all sealed up, almost. I did another baseline configuration set-up and calibration to see how everything would sound with the Stealth Box and rear carpet installed. The H660 cranked up all the gains (more so the high and mid range speaker channels) and changed the delay settings. It kept the Stealth Box JL sub at 0.0 delay as the central point and then cranked the left side channels to between 7 and 10 mili-seconds. The right side channels between 3 and 5 milliseconds. The effect is to make the car interior seem bigger than it really is. Crossovers on the PDX5 are turned-off (I control crossovers via the H660). The gains for Kickers are cranked all the way up and gains for the JLs are about 3 o’clock. The sub is on max. I fine tuned the eq, gain levels, delays, and crossovers on the H660 using my laptop and directly on H660 unit. I had a lot of fun experimenting and I am still making a few tweaks. I can also use the handheld remote to adjustment overall treble, midrange, bass tonality as well as subwoofer channel volume at any time. The remote is great for making subtle and quick changes for specific types of music on the fly.



You also notice the rubber strip of cable hider laying on the right side of the rear compartment. I used this in conjunction with some leather-look vinyl wrap to make a pair of covers that would conceal the cabling behind the H660 and PDX5.



I wrapped the vinyl (has an adhesive backing) around the rubber strips then carefully screwed the strips (without hitting any of the cables) in to the carpet behind the H660 and PDX. I also used some carpet tape to help hold it down. I like the results:





I made some minor changes with the Motorola T605 Bluetooth interface controller. I moved the location from the ashtray area (it used to be mounted below where the lighter would normally be located) to the upper dash area… next to the driver controls, just above and to the left of the radio head unit. It was a simple matter of re-routing the T605 cable towards to the top of bezel. It is mounted with 3M tape and Velcro. I capped of the hole where the lighter used to be in ashtray compartment and kept my Droid’s USB / charger cable in the ashtray spot. I typically just roll-up the cable stuff it in there… the Droid fits perfect over top and I can close the door to conceal / keep it from flying around the cockpit. Now that the T605 interface is up on the dash I can keep the compartment door closed, even to change music and make / take calls (all via the interface and voice control). In hindsight, I had the chance before closing everything up to run my HP Tuner control model USB cable through this same location but I didn’t think of it. Right now the HP Tuner USB cable is kept roll-up under the passenger foot well. I am thinking about getting one of those small backup video camera screens and installing it in the ashtray spot. That cigarette lighter hole will probably get used somehow for that.



I ran the 2 channel stereo mini-plug cable (which connects to the T605 aux input) and infrared transmitter for the H660 remote through the extra power / cigarette lighter hole of the middle console. The T605 lets you pair a media/ phone device via Bluetooth or directly connect to it via the stereo cable. I use this as my “guest” mp3 player connection so they can hear their own music.



No I had not yet vacuumed! Here is my power inverter which sends backup power via USB to the Droid. I also use it for the mini-laptop which runs HP Tuners. And that's the holster where I keep my side arm while driving.



Some pics of all the insulation that I yanked out. I can’t believe I had all that crap in there!





And finally, here it is… all clean and ready to roll.

lucky131969

great thread for the audio section..

hank_rearden1

thanks -- wasn't sure where to put it -- I figured there is enough going on in here that it could be more general technical in nature... should I move it?

lucky131969

up to you....just sayin there is a specific section for audio.....and I'm sure the guys that frequent that section will appreciate it.

hank_rearden1

Okay, I'll post a cross post to this thread in the Audio Section. Thanks

Vette28

I'm impressed by your ability to do something like this. I'm just a rookie at all this so maybe I shouldn't go overboard, but you should be proud of your skills and the way you presented this task here.

pentavolvo

Ill toss in a few things as an installer and have done countless c5 & c6 systems

Seeing as you have a dedicated sub why didnt you run components in the door, im confused as to why you went with an 8" sub and a 3.5"

Also as far as where you tapped in the line level outputs before the bose sound processor 100% work im not sure why they wouldnt work for you with the alpine processor maybe something wasnt connected right, i have tapped them numerous times to get a CLEAN output for amps. By tapping at the speaker level output you have no low end present in the signal, so the headunit is filtering out the bass to run to what was the stock speakers then your processor is boosting the living hell out of what was cut out. If you could get the line level outputs to work you would see a nice increase in soudn quality i bet

hank_rearden1

Thank you. Fact is, prior to the vette, the last automobile that I worked on (beyond a simple oil change) was my 1974 Chevy Malibu back in the late 80s.

I am okay with tools but I am not a craftsman. I could not make a living with my hands. I am just your weekend HomeDepot / Lowes hack harry home owner. I am do make a living in systems engineering though which just means I am good with concepts... I don't really build anything.

I just took things step by step, slowly. I think anyone who has an interest is doing this stuff can do it if their willing to make a few mistakes and invest in the time.

hank_rearden1

Great questions, thanks!

SPEAKERS --

The 8" Kickers in the front are dual cone and have a wide and strong low to mid frequencey range (30-500 hz: http://www.kicker.com/compvr). Technically they are "sub woofers" but their range really is more versitile. The really do a great job of delivering bass guitar -- think of Steve Harris, John Entwistle, Billy Sheehan. I like hearing the bass guitar in front (I am a guitar player and tend to follow the bass and hi-hatt). Also, the tom-toms tend come out of the front as well.

The 3.5" gives me the crisp high range (130 Hz - 22 KHz http://mobile.jlaudio.com/products_c...php?comp_id=58). So the hi-hatt and also comes through the front. These two sets of speakers are driven by independent sound processor sources (the front channel and rear channels, respectively) so the are effectively wired as "components" since each have different source channels. The sound frequencies delivered at the front of car thus create a natural "V" equalization image.

All of the mid-highs (electric guitar and snare drum and smaller tom toms) come from the rear 6.5" JLs (59 Hz - 22 KHz http://mobile.jlaudio.com/products_c...hp?comp_id=122). Which as a guitar player having played on stage, is from where I expect the guitar to project.

The Stealthbox in the back delivers all of the heavy bottom (bass drum and low-lows, reinforces the overall sound spectrum.

So the set-up projects really good instrument seperation...e.g. during a Neal Pert drum break-away, you feel the "movement" of the percussion around the car... you feell like you are sitting on the drum stool.

CONNECTIONS--

I did get a signal using the line level output [connector C3] but the H660 did not like it. I checked the wiring several times. I do understand how this will work when connecting directly to amps but I could not make it happen with the H660.

I was thinking the same thing you're getting at... I originally wanted the "clean" signal and was concerned the headunit (using the speakerouts [connectors C1 and C2]) would provide a crappy filtered signal. However, that is not what is happening.

The gains and eq settings that the H660 establishes during the set-up config for the bass spectrum do not appear extreme... if anything they are rather flat. I am guessing that the Bose head unit does not really filter or crossover any frequencys...and that the complete sound spectrum is in fact going out to what would be the stock twiddlers in the front and 6.5s in the rear. I think all the Bose Signal Processor does is capture the lows and amplify them... it don't know if the lows are being cut or filtered anywhere else in the stock system.

After reading your post, I connected my Droid directly to H660 aux inputs and adjusted the gains, crossovers, delays, and eqs to match those of the primary inputs (the headunit) to compare. I ran the Droid through the BlueTooth (head unit) and then connected it through to H660 aux directly. Obvisously, when I ran the the Droid directly to the H660 I turned the volume on the Droid all the way down at start-up and then slowly turned the volume up... the results were noticibly different but not significantly, i.e. when playing the Droid directly through Aux, bass sounded about the same...in terms of range but peak volume (gain) was less. Highs sounded about the same in terms of range but peak volume was also less. This suggests to me that the headunit C1 and C2 connectors deliver relatively neutral tone but with additional gain.