Fox Reinstalling Oem Stereo In 1990 Gt Convertible

Just FYI....those plastic mounting kits aren't needed on fox mustangs. My Kenwood is mounted in the original location with the factory cubby underneath. No screws. The metal jacket fits snug in the hole with the correct tabs bent correctly. Through 12 foxes and never used a mounting kit.
 
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I made a bit more progress on the electronics install. Audiocontrol tech support said the stock deck likely doesn't have enough voltage on it to trigger the LC7i to auto turn on, so I tapped into a 12v ignition switched wire under the dash and ran it back. With the amp gains all the way down, and the LC7i controls almost all the way up, it sounds very good. I think a line driver would help a lot though, in terms of lowering the signal to noise ratio. When the deck is below 1/2 volume, it's great. No real noise ... but when I get above 1/2 in the volume knob, you can hear a hiss during silent parts (ie: between songs, or really quiet parts of songs). I may look into a line driver in the future if it becomes an issue.

I've got it setup where the front channel of the deck is feeding the tweeters, and the rear channel of the deck is feeding the doors and subs. I also mounted the remote sub controller in the glove box. So from the driver's seat, you can control balance between all 3 (tweeters in dash, mids in doors, subs in rear) by adjusting the front/rear fader and the sub control knob in the glove box. This worked out nicely.

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I mounted the amp and LC7i in the trunk, with the amp on the passenger's side and the LC7i on the driver's side.

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I can still get to the spare tire, and with the trunk carpet in place, you really don't notice them.

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Next steps are to fill the holes in the dash left over from the aftermarket deck which used to be installed, and find a way to get the small subs mounted up.

As it stands right now, it sounds really great! This amp is really good for tuning, as it allowed me to high pass the tweeters, band pass the door mids, and also band pass the subs (with a low pass and a sub-sonic filter).

The USB cassette adapter is working out really nice as well. The quality from it is better than I expected it to be. I can still hear the motor turning in the unit, but I wonder if I can just open up the deck and disable the motor? Since the adapter doesn't really need to spin, this may be an option. The only thing about this adapter is you have to remember to charge it about every 4 hours of use. Not a big deal, but can be annoying if you forget and want to use it immediately.
 
About the hissing... where are your grounds hooked up to? Sounds like a ground loop issue. You can try to turn the controller down some and up the gain on the amp, ideally you would get the line voltage from the controller to equal the gain. (There is a way to test and do this I would Google that part as I have not done this in awhile.)
 
The grounds for the amp and the LC7i are hooked to the trunk hinge bolt. The deck ground is through the factory harness. I've experienced group loops before, and they're usually a whine which follows the RPMs. But to be honest, I haven't driven the car yet with the new equipment, so it might actually do that! If it does, I'll be certain to redo the ground ... good call.

The amp's input sensitivity range is 200mv to 6v, and I stuck a meter set to AC voltage on the output of the LC7i, and it fluctuated around .4 - .5. Since the meters scale was set to 200 (lowest it will go), it's about 500mv. So the amp gain is set for the 6v setting, yet I'm feeding it 500mv. Tech support told me the LC7i's output voltage would be impacted by the low signal coming in. He actually recommended a line driver because the signal from the deck was so weak (it's not even enough to trigger the auto power on circuit).

So knowing that, I should technically crank the amplifier's gain controls to almost full in order to match it, but then I'll get horrible distortion if the deck's volume get's anywhere above 20%. These speakers can't handle anymore than that. I should really replace the speakers with less sensitive ones for a better match. The little subs have a really low sensitivity (83dB), so I'm sure I could crank it up after these are installed; but the front components which were already installed when we got the car, are high sensitivity MB Quart components, and they are very lacking in definition. I assume the installer did that beacuse they were running them directly off the aftermarket deck which was installed. I'll eventually replace them with something better, but that probably won't happen until next month sometime.

I think I might be talking myself into a line driver here, as I'm not sure how good the s/n ratio can be with a maximum of 500mv. The line driver could boost the output of the LC7i up above 4v to feed into the PPI amp and help greatly.

So, shopping list for next month looks to be some quality, low sensitivity components, and a quality line driver if the hiss is something which bothers me. I really won't know until we've had some time to experience the sound while just driving around.
 
Just so you know, I use mb quart components in my car. I'm driving 200w to each at 4 ohms. But I have 6v off the head unit..... I don't get distortion till its loud enough to make your ears hurt.

I do run a flat eq. I also ditched the quart tweets in favor of clarion ones, the woofers are real clean sounding above 120hz. I let my 2 quart 6x9 do all the mid bass. Food for thought.
 
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Ya, I actually have a set of MB Quart OSC216 components in my 2005 GTO, and they sound great with my setup there (Pioneer DEH-80PRS, PPI4240 amp). The OSC216 set is rated at 88 dB sensitivity and use a silk tweeter though, and the 80PRS has 5v outputs, as well as built in EQ, crossovers, time delay, etc, etc, etc ... It's a fantastic head unit for SQ to say the least

I don't know the model of the set in the mustang, but the tweeter material is metal (maybe aluminum?) and they must be high sensitivity drivers based on what I'm hearing from them (they're really harsh when the volume gets up). They're also somewhere around 15 years old, in addition to the old convertible top leaking water at one point, I think they're just not the right speaker for the job here. I do like MB Quart, and may replace them with a newer, better matched, set of MB Quart components. Just need to start the research to determine what is a good match here.

The Black Ice BA2200.5 PPI amp is rated 90w @ 4ohm with a s/n ratio >100 dB, so my options should be plenty for a well matched set of components to provide clean sound.

Of course, if the 500mv input signal is going to be an issue, I'll still need a line driver at some point.
 
Will do. If I can fit 6.5" or even 6.75" in the doors without having to fabricate anything, that would be best. I think the ones in there right now are 5.25".

Crutchfield seems to think some of the 6.5" ones will fit. I suppose it's the depth you have to watch out for.
 
Look what I came across for a subwoofer option in the 5x7 location:

Tang Band W57-1781

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Two of these, in parallel for a 4-ohm load, would probably sound great in the mustang. It says "Call for pricing" though, so maybe they don't make them anymore? I'll call later today. This would be a drop-in speaker option and play down to 40hz. Great mid-bass and moderate sub-bass.



Product Specifications
  • Nominal Diameter 5"
  • Power Handling (RMS) 50 Watts
  • Power Handling (max) 100 Watts
  • Impedance 8 ohms
  • Frequency Response 40 to 500 Hz
  • Sensitivity 87 dB 1W/1m
  • Voice Coil Diameter 1.5"
Thiele-Small Parameters
  • Resonant Frequency (Fs) 40 Hz
  • DC Resistance (Re) 7.2 ohms
  • Voice Coil Inductance (Le) 0.38 mH
  • Mechanical Q (Qms) 2.12
  • Electromagnetic Q (Qes) 0.3
  • Total Q (Qts) 0.27
  • Compliance Equivalent Volume (Vas) 0.92 ft.³
  • Mechanical Compliance of Suspension (Cms) 0.97 mm/N
  • BL Product (BL) 10.35 Tm
  • Diaphragm Mass Inc. Airload (Mms) 19.96g
  • Maximum Linear Excursion (Xmax) 3 mm
  • Surface Area of Cone (Sd) 140 cm²
 
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Looks like the 5x7 can only be ordered in quantities of 300 or more :(

They do have a 6x9 option though. Does anyone know the max depth of the rear speaker locations in a 1990 convertible? Also, I assume a 6x9 will fit into the factory mounting configuration ... is this safe to assume?

Tang Band 6x9 Subwoofer W69-1042J
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Product Specifications
  • Nominal Diameter6" x 9"
  • Power Handling (RMS)90 Watts
  • Power Handling (max)170 Watts
  • Impedance8 ohms
  • Frequency Response35 to 350 Hz
  • Sensitivity87 dB 1W/1m
  • Voice Coil Diameter1.5"
  • Magnet Weight29.2 oz.
Thiele-Small Parameters
  • Resonant Frequency (Fs)35 Hz
  • DC Resistance (Re)6.5 ohms
  • Voice Coil Inductance (Le)0.91 mH
  • Mechanical Q (Qms)3.93
  • Electromagnetic Q (Qes)0.4
  • Total Q (Qts)0.35
  • Compliance Equivalent Volume (Vas)1.07 ft.³
  • Mechanical Compliance of Suspension (Cms)0.42 mm/N
  • BL Product (BL)13.27 Tm
  • Moving Mass Of Diaphragm (Mmd)49.89
  • Maximum Linear Excursion (Xmax)7.3 mm
 
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One more small update: I decided to make two small trim strips to hide the holes instead of filling, sanding and painting. I used the plastic material from the other half of the radio delete plate and cut the strips, then fine tuned them to fit on each side. The strips are about 1/2" wide by 5" long, and I think it came out ok. Definitely better than the holes.

The one nice thing about the trim strips is they make up the space in depth that the radio sticks out. So the radio, the storage cubby and the strips are now all on an even plane. I'm pleased with it :)

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I used mine for a short time in my 89 gt it was ok but limited because of the speakers, and the tape deck started to eat the tapes, good for a stock setup with better speakers, depends on your expectations.
 
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I always find this to be a double edge sword. I understand that someone would want to keep a "stock appearance" if they are trying to maintain the original condition of the vehicle. But for any reason other than that,....Who wants an analog radio based on 80's tech, and a cassette deck? Having to use the factory head unit for ANYTHING is a compromise. You cannot adapt the cassette deck to allow you to play your Iphone through w/o it sounding like ass,..you cannot use an FM modulator for the same purpose, w/o it sounding like ass,... seriously.

Here's the same thing I posted over on crotchedy town where the prune juice gang over at FEP prefers their factory stuff to something like what's posted above because the sound is "good enough", or that they'd rather listen to their "Flows".:nonono:


*** papers rustling as he steps up to the lectern...

As an audio guy, it always pains me when I read stuff like this on a forum. Using ANY adapter is just one more erosion of what people accept as decent sound quality.

Music sources have always been measured by two references: Frequency response, and Signal to noise.

Frequency response is typically seen as a measurement of the sources ability to reproduce the distance between the lowest low frequency, to the highest high frequency, measured in hertz (Hz)
The normal human ear can hear a range between 20hz to 20,000 hz (most commonly referred to 20 kilohertz, or 20 khz)
A super low thud from a bass guitar, kick drum, or bass machine can easily reproduce a 20 hz note, and is more often "felt" by us, rather than heard.
Conversely, a 20khz note is a super bright ting of a cymbal, or the noise your ear hears as a ping when a tuning fork is struck.

Every musical instrument, including a human voice falls between those two ranges.

Signal to Noise is the sources ability to convey that signal w/o adding anything else (in the form of distortion) to that signal conveyance. Think of that as a percentage.

So, as an example: If you sat in front of band making a recording in a studio environment free from any other noise clutter, that would be 100% authentic. The S/N would be 100db. You'd be able to hear everything, from the lowest low to the highest high.
A CD copy of that session would be at the 90%, or 90db S/N. The frequency response would be between 10-22khz (beyond human hearing)
A Cassette copy of that session would be at the 70db S/N. W/ a 30hz-18khz FR. (when played back on a high quality, home cassette deck)
A FM broadcast of that session would also be around 70db, w/ even less FR more like 30hz-15khz.

Now, when you add in the old factory radio which was notoriously bad in the mid 80's, you can also subtract about 10% from anything rated above.
Lastly,...add in the degradation of a cheap adapter, and you get a flaming pile of crap.

A cheap dollar store cassette adapter will probably show actual S/N in the 60-65db range, w/ a FR somewhere in the 50hz-15khz range
A FM modulator placed in line of the antenna will be even worse, 55-60db, w/ a lousy FR at 50hz to 13.5-15khz.

If your radio has an aux input on the back (which some factory head units have) use it. The S/N, and FR will be best that way, as it is a direct audio connection. I cannot tell what that input source is rated at though, but it will be as close to CD quality as you'll get. The pic of that female aux jack wired into the front trim is just a quick way to connect your listening device w/o having a cable laying around that is hooked to the back of the factory aux input.

http://www.crutchfield.com/S-1mCjqJzp78X/learn/learningcenter/car/oem/connections_sound_quality.html

Newer stand alone head units have HD radio,..and granted, it's only FM,..but now local stations sound better than Sirius, and are typically broadcasting multiple "streams" of music on each of their dedicated frequencies. In other words,...if you like a classic rock channel, and have one in your market,..they are usually playing two-three different songs at the same time on two-three different sub channels under that frequency.

Compressed music files, and the service that hosts them, i.e. Itunes are just that....compressed. When music is compressed for the sake of fitting more songs into a given space, the end result is that both ends of the frequency response are clipped off.
The direct end result being that when comparing a compressed version of that song, to a CD version,..the compressed version lacks the punch the realism, and clarity that the CD versions has.

Why is that OK?
Why is that good enough?

There is stuff out there,...and if all you're trying to do is put the factory face on, and hide a bluetooth interface so that you can stream music via bluetooth, it's only a google away. But depending on how it's tied into the existing audio system...(in other words,..if it uses the factory amplification and speakers to be heard,)..it offers little more than convenience.
In order to truly get a foot up over the factory junk,..it all has to be replaced. The factory speakers (if not completely shot) sounded like ass the day that car rolled off the assembly line.

The single most significant thing you can do to improve sound quality in one of these cars is to junk the factory speakers.

The 3.5" speaker in the dash, and the 6 x 8's in the rear quarter trim were one way speakers w/ "whizzer cones". i.e they have a little paper cone lookin dealy that was an attempt to "confine" the high frequencies and separate them from the rest of the blah-blah-blah sound quality of most one way speakers.

Throw that junk away,...aftermarket speakers intended to replace the factory crap are all over the market and are a vast improvement over the stock crap. (and nobody will be the wiser that you changed a thing)

After that,..if you just gotta have your factory facade,..then there are several companies selling a invisible interface that replaces the factory HU as the amp and serves as an interface to tie your phone into so that Pandora/Spotify/Rhapsody, and a whole buttload of other streaming services can play through to your system from your phone.
Then you can split the power wire so your little green clock on the radio stays hot, and still have something better sounding than that dumped, no cat, Flowmaster 40 drone to listen to.

Done.
 
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