Well I finally got around to my stereo project today. I went out and stole the subs from my wife's car and bought a new amp for the build. I have a pair of 10" Rockford Fosgate Punch subs, they are pretty cheap single voice coil subs but they should be more than enough for the little fiero. They say 400W max on the back of them, guess that should be maybe 150W rms a piece?

I went to Best Buy and bought a nice Kenwood amp. I was pleasantly surprised when they demo'd the amp for me, they started with the low end subs all the way up to the high end and it seemed to pound pretty good with all of them. Its a Kenwood model KAC-8101D. 1000W max power, probibly around 4 or 500W rms.

Here are my pictures so far.

These subs are nice because they are pretty shallow. They are only 5" deep.

If anyone here can tell me how to run my amp I would appreciate it. They were out of the amps I wanted and ended up selling me a demo model. I have no instruction sheets. Here is a picture of the controls. My subs are single coil and 4 ohm. How would I run this for the most effect? The salesman was taking way over my head, I'm kind of new to car audio. I think he said I want to run monoblock for both subs. I'll let you guys tell me, there are plenty of audio fans here. The amp is 2 channel, how would I go about running monoblock? How do you wire that?

And here is the damage I've done to my car so far. I bought some fiberglass to seal off the enclosures and I'm making my box to come out 4" from the firewall. This should give me 3" behind the sub so the firewall doesn't interfere. It will also allow me to upgrade the subs in the future if I want.

Any helpful tips and tricks any of you have would be great.

Thanks!

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86GT 4 speed LT1 conversion underway

I guess you didn't see these speakers, they would have saved you a lot of work, or at least some leg room.
http://www.blaupunktusa.com/BlaupunktUSA/Products/Speakers/Overdrive/Subwoofer/ODw10 00.htm

[This message has been edited by avengador1 (edited 05-24-2004).]

hmmm $400 a piece, that would be $800, probibly $1100 Canadain, I think I'll stick to stealing from my wife

The two 10" subs will be more than enough to fill the cabin with bass. I had a pair of Blaupunkt 10" subs with a 2x75W RMS amp, and had to turn the gain down to about 50% to preserve my hearing.

Since you're using 4 Ohm speakers, I think it would be best to wire them in stereo mode (i.e. left and right), and don't bridge the amp. If you're dead-set on running the amp bridged (i.e. in monoblock mode), then you should wire the speakers in series. If you wire them in parallel, you'll end up with a 1 Ohm load, which the amp may not be able to handle. You should ask the salesman if the amp is 1 Ohm stable.

As far as connecting and configuring is concerned...

-- I don't see a bridging switch. Maybe it's on the other side? The bridging switch will put the amp in monoblock mode. When in monoblock mode, you'd connect the speaker(s) to the left output only.
-- You can run a stereo RCA cable from the head unit to the LINE IN connectors. The other side of the amp should have binding posts for the speaker outputs and power/ground/sense circuits.
-- I have no idea what the ENHANCER switch is for... loudness maybe?
-- The INFRASONIC switch appears to be a rumble filter. It filters out subsonic frequencies (which you can't hear). It not only helps to reduce chassis vibration, but will also leave more power for the amp to generate the audible bass (i.e. better sound quality). I'd set it for 20Hz, or whatever the right side says.
-- The BASS BOOST is most likely going to be at 45Hz. It will improve the deep bass
-- The LFE FREQUENCY is the low-pass crossover. It makes sure the subwoofer(s) only produce bass. I think 100Hz is a good starting point. Then tweak it up or down until you don't have any dead spots or loud spots in the bass range.
-- INPUT SENSITIVITY is the gain control, basically a volume control
-- The SPEAKER LEVEL INPUT won't be used, unless you want to connect the amp to the speaker outputs of your head unit (rather than RCA cable)

Did that help?

[This message has been edited by Blacktree (edited 05-24-2004).]

Thanks, that helped alot. That one switch is called the expander, its an on off switch, have no idea what it does.

There is no bridging switch on the amp, the only thing on the other side are the power terminals. It doesn't lable the speaker outputs to run bridged or not like I've seen on other amps that I've owned. I was thinking I would get better sound running mono, get the subs doing the same thing, does that make sense?

Thanks again

My subwoofer amp doesn't have a bridging switch, either. But it has a little diagram showing how to "manually" bridge it. You connect the speaker(s) to the left positive and right negative on the amp. I'm not 100% sure this will work on yours, but you could try it. I'd suggest having the speakers wired in series, for 4 Ohms total impedence.

quote ...the only thing on the other side are the power terminals.

Then the SPEAKER LEVEL INPUT probably has the speaker outputs, too. I hope you got the plug-in connector for that. You might need it to connect the speakers.

BTW, the LINE OUTS are probably just pass-throughs so you can daisy-chain a second amp.

[This message has been edited by Blacktree (edited 05-24-2004).]

Working with Mono foam + fiberglass = 1 sticky mess.

This is the first coat of resin, I will put on another when it dries. I have new found respect for people that work with this stuff on a regular basis.

[This message has been edited by crzyone (edited 05-25-2004).]

I did a Google search for your amp. You don't need to worry about bridging it, because it's a monoblock amp. Kenwood's website has detailed specs.

[This message has been edited by Blacktree (edited 05-25-2004).]

If you wire the 2 4 ohm speakers in parallel you will have a 2ohm load, not 1 ohm.. Your amp should be able to handle it.

James Z

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quote Originally posted by SplineZ: If you wire the 2 4 ohm speakers in parallel you will have a 2ohm load, not 1 ohm.. Your amp should be able to handle it.

That is correct. To present a 1 ohm load to an amplifier using 4 Ohm voice coils you would need 4 speakers and wire them in parallel to each other.

If 2 or more resisters are wired in series, then the total circut resistance is additive of each other.
IE: Rt = R1 + R2 + R3 + ... Rn

The formula for figuring out total resistance (load) for a parallel circut is a little more complex.
Total circut resistance is equivulant to the reciprocals of each resistor in the circut added together.

[This message has been edited by datacop (edited 05-25-2004).]

NM, missed the one post stating that is a mono amp....
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www.FieroLoki.com

[This message has been edited by Loki (edited 05-25-2004).]

Thanks guys, I do remember him saying it was a monoblock amp. So by the specs on the site does it sound like a good amp?

I'm getting high on resin fumes today, have both fiberglass enclosures done, just working on the sub box now. I should have some more pictures tonight.

+ for all that helped!

By the way, did you happen to see which terminals I need to hook the wires up to on the amp? Do I use all 4 or just 2?

Thanks!

you should only need to use 2 terminals for the speakers, it should be left + and right -
it should be written over the speaker connections which ones to use when bridged.

quote If you wire the 2 4 ohm speakers in parallel you will have a 2ohm load, not 1 ohm.

Since we NOW know that it's a monoblock amp, you are correct.

quote By the way, did you happen to see which terminals I need to hook the wires up to on the amp? Do I use all 4 or just 2?

I'm not sure. I really don't know why a mono amp would have two pairs of speaker outputs.

Hey, I just found an online PDF manual for a similar model amp. I couldn't find your exact model, but this one is pretty close. LINK

[This message has been edited by Blacktree (edited 05-25-2004).]

hmmm... I have had my heart set on mounting the 10" alpine sub of mine in the passenger side footwell with a custom box but now that i see cutting the firewall isnt THAT difficult you might have convinced me.. So how deep is the firewall back there, how far forward would i have to push the seat up to get .7 cubic feet for a sealed box?

Here is a picture of the terminals, not sure why it would have 2 sets.

Here is the sub box as of now, its pretty much done. I made the box all nice and square, went to put it in the car and realized the car isn't nice and square. So I turned a mistake into progress and glassed the stupid thing in... I'll probibly end up loosing 5" of leg room, good thing I'm short Just need to cut the holes into the fronts and carpet the boxes.

quote Originally posted by Blacktree: I'm not sure. I really don't know why a mono amp would have two pairs of speaker outputs. Hey, I just found an online PDF manual for a similar model amp. I couldn't find your exact model, but this one is pretty close. LINK

That's actually fairly common and done to make the install look clean. The two sets of terminals are wired in parallel to each other. Internally, the amp is wired mono.. but two terminal sets are presented so that you can wire two voice coils (either 2 speakers or a duel voice coil speaker) to the amp without having to double the wires on the terminal connector. The reason they do this is to limit the ammount of current flowing through a single terminal set (read, it keeps 'em cooler).

My MTX 1000 Monoblock is the same way as is the Audobauhn Class D monoblocks I've worked with.

Youre amp is a newer version of mine. It has two outputs cause you dont have to run mono if you dont want to. If you want better sound wire them to the outputs right and left. If you want max bass run in mono mode. I am currently running the older 750 series and have 2 15" subs. I have sucessfully powerd 2 1000W fosgate 12" subs and it wont overheat. I have made numerous trips of 3hrs plus with the sterio cranked and the amp is only luke warm Best amp ever!!!! and I got it for $200 in a pawn shop he he. I think you will be VERY happy with it

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85 GT 4 speed 2.8L auto X'er

DONE!!!

Well, now I just need to carpet it and modify my fiero carpet to go around the boxes. Putting the pillar trim piece back in should be a ton of fun.. I can see some modifying there. The indide volume of my boxes should be around 22 1/2" by 16 1/2" by 4" So that should be 1485ci. That should be about .86 cubic feet plus alittle for the firewall cutouts, probibly .9 all together. I wanted to leave it big so I can upgrade the subs later on if I want. Thanks for looking! I'll post more pictures when its finished.

Back massage anyone?

[This message has been edited by crzyone (edited 05-26-2004).]

Nicely done! Can't wait to see it at the next meeting! Keep up the good work.

Looks great! Nice work. Caint wait to here from you, how it sounds.

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-Chris

Custom Gun Metal 86 GT
Look here for more pics - https://www.fiero.nl/forum/Forum1/HTML/040573.html

***95 Camaro 3.4 swap, Ported and polished heads and intakes, Ported plenium, 57mm Throttle body, Sprint Headers, CRX CAI, Custom Cam, AFP Regulator, steel vacuum lines, steel braided EGR tube, new Wire Harness, New Exhaust, No Cat, Flowmaster, polished poly dog bone. Isuzu 5 speed, Short through shifter
***Intrax 2" drop springs, Full Polly Suspension, Sencetrack Struts and Shocks, Grand AM brake upgrade, steel braided brake lines, 17" Gun Metal Wheels, Khumo Tires
***Racing Seats, SunPro tach w/ shift light, White face guages, carbon fiber Steering wheel, Carbon Fiber dash accents and custom sphere shift knob,

crzyone... Looking good so far!

After you test fire it, it may sound "boomy" - not BASSy. This will be from distortion and resonances inside the box. You may need to add some polyfill inside the box to smooth it out. The speaker will then work more efficiently and quality should be better.

You can fine tune the box by how much you put in there. If you change to bigger subs later, you'll probably need to add more. Polyfill can increase the "apparent" volume of the box by 40%. With polyfill, you can actually build a smaller box and "get away" with it, while still getting awesome performance in the end.

http://diyaudiocorner.tripod.com/faq.htm

My sub-boxes have 1lb of polyfill in each. Only a couple bucks from Walmart.

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Fiero Fiesta - August 1, 2004 - Calgary, Alberta <--- click this LINK

3.4L S/C 87 GT www.fierosound.com
2002/2003/2003 World of Wheels Winner &
Multiple IASCA Stereo Award Winner

Thanks for the info, the link was awesome. I'm glad I didn't carpet the boxes yet, need to pull the fronts off and add some insulation. I looked up the specs on my subs and it says optimum cubic feet is .85 or so and I think I'm running around .9 so is it good to be alittle big?

I feel like I should remove the fronts, add a layer of fiberglass everywhere and add polyfill to insulate the inside. I want a nice sounding system, I've had "loud" systems before but I'm looking for quality this time. I have pioneer 4 by 10s in the front, need to replace my 4 by 6s though.

I havn't been able to listen to my subs yet, broke my clutch fork a week ago and pulled my engine, hopefully in another week or so it should be back on the road.

Thanks!

The front panels should be glued/screwed onto the frames to be stronger, better sealed, and be less prone to work loose and rattle over time. You can just pull the subwoofer and push polyfill in through there. Since your box is close to optimal size, you'd probably need only enough to cancel/absorb reflections inside the box. When you change to a different sub the box may need to be "bigger" and that's when polyfill will help create the appearance of that for the sub.

quote Originally posted by datacop: The formula for figuring out total resistance (load) for a parallel circut is a little more complex. Total circut resistance is equivulant to the reciprocals of each resistor in the circut added together.

Eh, almost- total resistance is the reciprocal of the reciprocals of each resistor added together, so

1/total resistance = 1/R1 + 1/R2 + ...

I was actually thinking of finding some thin rubber gasket material and putting it around the fonts and then screwing them down good. I want them removable so I can easily take them out and modify the box if need be. Need another layer of fiberglass everywhere, not quite sure they are perfectly sealed with just one layer.

A newer version of my subs

Says they are 200W rms, should sound pretty good

Thanks!

I would advice to use some more fiberglass to seal the edges between body and subbox even better..
Theres some grey vinyl/leather thats close to the interior grey, might be nice for coverings the boxes...
anyway, nice work!

Took me long enough, finally had some good weather and some free time and carpeted my subs. Carpet doesn't match the stock fiero carpet but I actually like the way it looks. It sounds pretty good, I ended up not putting insulation in the boxes, I'm completely happy with the way it sounds. Its definitly not loud like some stereos I hear comming from 2 blocks away, but it sure gives the songs some punch. I ended up mounting the amp in the trunk. I thought I might be able to squeeze it under the seats but there is nowhere near enough room.

Thanks for looking!

[This message has been edited by crzyone (edited 07-10-2004).]

Very, very nice. Those Rockford Z series subs probably won't give you the BOOM you want (if that's what you were shooting for) but once you think your in need of an upgrade, there are plenty of subs that'll rattle your brains and blurr your vision. Wish I had the balls to cut into my firewall.

Good Job

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*~ Out In The West Coast Showin' Off My Bad Habits ~*

WOW! Thats some really nice work! I just couldn't afford to loose that much leg room. (6'-1") Thanks for the build pics!

[This message has been edited by Convertable Indy (edited 07-11-2004).]

Surprisingly, when I move the seat all the way back now I'm to far away and can't push the clutch in all the way. (5'8") Passenger still has all kinds of room as well. I would say this would be good for anyone 6' or under, I even lent the car to my father who is 6' and he didn't complain at all.

Wow, very impressive. Very clean install. A "+" for you.

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The rebirth of 72vinman

Very nice install!

On the amp install; a lot of fiero guys mount them above the sub in the box. The amp is still behind the seat in a complete package. Downsides would obviously be rebuilding the box for it.

Now you have me looking at a behind-seat install...

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Wanted to Trade:
My 87 SE V6 for your 84-88 4cyl manual fiero.
PM me for details

Real nice clean install and great documentation...but I don't know how you guys can afford to lose the legroom. I would push my seat back another 3 inches if I could. I might sacrifice the passenger side but there is no way I could do that on the driver's side, and I'm only 5'10".

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1988 GT (Firebird Interior),1988 Coupe (Daily Driver), 1985 SE (Project Car), 1985 Coupe (parts car), Firebird Interior Installation Website

You used 4" tall wood pieces? What type of wood was that, loos like pine?

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Bobby from NW Indiana
93 Northstar and 5 speed Getrag
thespeedshop@sbcglobal.net
My build thread

if he tapered the wood peices from bottom to top a bit then it'd be perfect.. i never slide the bottom all the way back - but the headrest is always against the firewall (6'4")

quote Originally posted by jscott1: Real nice clean install and great documentation...but I don't know how you guys can afford to lose the legroom. I would push my seat back another 3 inches if I could. I might sacrifice the passenger side but there is no way I could do that on the driver's side, and I'm only 5'10".

It's gotta be in the legs.... My girlfriend is 5', and a friend of hers is probably 5' 9". Thier upper bodies are almost the same, but damn her friend has a lot of leg! They would end up with almost the same headroom in a car, but my girl pushes the seat waaaay up, while her friend wouldn't have to.. I used to drive with a HUGE box behind the seat of my Fiero. I was all stuffed into the steering wheel, but man what a massage I got! Looks good there crzyone!

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Bob Williams
Multi-colored '87 Mutt, a work in progress! (3800SC installation in super-super-ssuuppeerr-slow-motion progress... Done for Kansas? Riiiiiiiight....)