Car Audiophile? Amp Questions Inside...

[Automan2164]

Well... I have been playing around a bit with the audio system in the '97 Cherokee. Can't leave well enough alone. The look and output of the stock radio worked great. Then it started losing the right hand speaker. Then it lost it completely. My '98 Grand hadn't sold yet, so I just did the ol' switcharoo. While I was in there, I took out the 6.5" Infiniti Kappa speakers I had all around and put the XJ ones in the grand. All was well.

 

I found a factory subwoofer for the XJ on the shelf NOS, so I put that in also. It taps off the stock radio with an inline harness and runs to the back. It powers a 50W amp running an 8" sub. Added depth and richness to the sound that was sorely missed.

 

 

Then I picked up the tweeter grilles for behind the mirrors, and put those in with some middle of the road tweeters w/bass blockers.

 

 

Then the ZJ radio in the XJ started to go out. It would lose output to both front speakers, and not come back until cutting power and putting it back. Tired of the problems at this point, I decided to just replace the head unit, even though my OCD didn't want to comply. Ended up getting a Kenwood single DIN with all the bells and whistles. This is where the problems started.

 

The new HU overpowered the subwoofer. First, it tore out the dusty old surround on the speaker. At a loss to find a replacement speaker, I just found some new foam surrounds on eBay, and I just replaced that. All was good for a day, until the subwoofer coil bit it. My fun was done for awhile, and I kept up the search for an 8". Nothing seemed to work. The local audio shop ordered some stuff to try, but even the shallow 8's were too deep. Then I did some searching on eBay, and found a super cheapo 8" sub that mirrored the stock one for $25. Worth a shot. When I opened the box, I was elated.

 

 

 

All was well for about a week. I was jamming out, then I noticed the bass just wasn't there. Fuse was blown to the amp. I replaced it, and as soon as I keyed up, blam. Fried it. Ruling out the wires getting pinched, I unplugged the amp to check if it would still blow. Nope, but as soon as the amp was plugged back in, blammo. I am assuming that now that the speaker is newer and decent, the amp finally gave up the ghost. I tried talking to the local audio guy, but nothing he had would really work... Most of his stuff is pretty high end, and I just don't see spending $200 on an amp just to run an 8". He called my stock Mopar amp a printed board or boarded amp, has the fiber board with all the components soldered on. I took it apart to check for any obviously damaged components or melting, but found nothing.

 

This is where my audio knowledge ends... I am not much of an audio guy as much as a 'Yeah, that sounds good' guy. I was wondering if any of you guys may have an idea of a replacement amp (stock is listed in the catalog as 50W) to run my cheapo 8" sub. I am just looking for something that will do the trick without going over the top. Preferably, something smaller or compact. (The stock amp sits recessed in that black box).

 

Any help or advice is appreciated in advance.

Rob :cheers:

[GirsMJ86]

I'll show your dilemma to my cousin who is a DJ and builds custom systems for stage use and car use. If he knows of something he can usually get a good deal on stuff too because of all the business he does.

[dave92cherokee]

You could always get a different amp and mount it in the cubby hole on the other side of the hatch then run the wires under the carpet to the sub then you can get one that's closer suited to the sub's needs instead of fighting with space constraints.

[knever3]

You have my interest!!!!

 

There are so many questions I have.  Do you have the full Infinity system from the factory?  If you do there should be an amp under the rear seat and one in the back for that sub you mentioned.  When you replaced the OE infinity radio did you use a conversion box like this one? 

 

http://www.amazon.com/Scosche-Oea4-4-Channel-Adjustable-Amplifier/dp/B00009UHSO

 

If you have the amp under the seat you need to step down the input voltage to the amp from the aftermarket radio speaker outputs.  If you don't use an adapter you will overload the input on the factory amp and make it "Clip".  Odds are the aftermarket radio you have has more power than the factory amp.

 

I can't see the pictures you posted because I'm at work so I am going to have to wing my response.  You can look for a factory replacement amp but to be honest they are garbage.  You have a tight budget but it can be done with a used amp if you don't mind taking up some space.  If you want to hide the amp behind the panel go with the Rockford amp in this link:

 

http://www.ebay.com/itm/Rockford-Fosgate-PBR300X1-300W-Monoblock-Class-BR-Punch-Car-Amplifier-Amp-/300927711805?pt=Car_Amplifiers&hash=item4610b07a3d#ht_2201wt_1399

 

I know it says 300W, but that's at 1ohm.  Your speaker is most likely 4ohms so it will put out 75 watts of clean power.  First you need to get an adapter to integrate that aftermarket radio to use the infinity system.  I have years of installation experience with car audio so I can be here to help.  Maybe when I get home today I can see your pictures.

[Automan2164]

Dave92cherokee, I was really trying to not do that. If I can't get an amp that fits into the spot for it, I was just going to seal that hole to keep the enclosure air tight, and mount the amp over the top of it.

 

Knever3, I don't have the full Infiniti system from factory. I wish I did, but from what I gather, that was a unicorn rare option. You are correct in assuming that the sub is a 4 Ohm variety. It is nothing special though, here is the back view... Very cheap(Like factory sub style speaker), but it was the only thing that would work for the space concerns.

 

 

 

That amp you posted looks perfect, and is certainly small enough for me to mount it where ever I would want. Price is on the high side for me though. Another question would be if this amp could or would overpower the little cheapo 8". I am pretty sure that I am abandoning the stock wiring, and will have to put it on the HU's subwoofer output, so I should now be able to isolate the bass level independent of the speakers. As it is now, the general bass eq's for everything also works the sub's bass.

 

Rob

[knever3]

Ok, I'm home from work finally.

 

I see what you were referring to.  The factory amp is probably bad since it's seen way to much voltage on the input from your new deck.    The amp is very efficient but you may want to run a 8awg wire to the battery to power it, don't forget to fuse it!.  It's only 4" x 6" so it will fit in the space that the old amp is residing now it looks like.  When you buy a set of rca's for the amp run a remote wire with it to your head unit to turn it on.  The factory wiring is not sized large enough to power the new Rockford amp.  Don't be worried about the new amp being to much power for the sub, you have a gain on the amp and it sounds like you have a dedicated sub level out on your deck.

 

That should solve your problem if you are willing to spend a little money.

[knever3]

Or...

 

You could do what I did and build yourself a box to replace that space saver spare.

 

 

 

Old Pioneer deck and a Audio Control preamp

 

 

And just for kicks a 5 channel amp under the driver's seat to run everything

 

[Automan2164]

I revive thee from the dead!

 

Felt spritely and such, tired of looking at an empty shell in the spare tire.

 

Ordered the amp. Should be here next Wednesday. Now just have to find the time to put it in.

 

Rob

[knever3]

Sweet, let us know how it performs!

[knever3]

I revive thee from the dead!

 

Felt spritely and such, tired of looking at an empty shell in the spare tire.

 

Ordered the amp. Should be here next Wednesday. Now just have to find the time to put it in.

 

Rob

So, what are the results of this experiment Rob?

[Automan2164]

Sorry... Still sitting on the coffee table... That whole time to do it thing is a big hinderance. I am wrapping up some home improvement projects at the moment, so maybe soon. I haven't set aside the time needed to run 10 ga from the battery all the way to the back opposite corner.

 

Rob

[knever3]

I can relate.

[Automan2164]

Finished the install today to the point where it is operational. Need to take some pics once I get it all cleaned out.

 

Kevin, any setup tips? I have never had an amp/sub such as this... Only a bazooka tube and that stock factory amp. This has a lot of features.

 

Rob

[knever3]

There shouldn't be much to setting it up.  Did you use RCA's from your radio?  I don't know if your radio has dedicated RCA's for a sub but if it does use those.  You should have a sub level adjustment and crossover in the radio.  If you give me the model of the radio I could help you more.  If you don't have a sub level on your radio and crossover use the one in the amp.  Usually for an 8" around 80-100Hz is where you want it set.  If it's too high it will sound muddy and draw your ears to the back of the Jeep.  I guess I'll wait till I hear and see what you have!  Congrats I hope it sounds good.

 

I have been working on some audio upgrades on my Comanche too.  I need to build a fiberglass sub box for behind the seat and an amp board to match.  I am putting in new door speakers and crossovers too.  Can't wait!!  Plus it's been 3 months since my engine was taken to the machine shop.  I'm over being anxious, just patient now.

Finished the install today to the point where it is operational. Need to take some pics once I get it all cleaned out.

Kevin, any setup tips? I have never had an amp/sub such as this... Only a bazooka tube and that stock factory amp. This has a lot of features.

Rob

[Automan2164]

I have a Kenwood BT755HD:

 

http://www.crutchfield.com/S-kfl5drO7SFB/p_113BT755HD/Kenwood-KDC-BT755HD.html#details-tab

 

It has the dedicated line out for the Sub, but the only setting I can find for it is the "Sub Level" and it goes up from 0 in odd increments, IE 1, 3, 5, 7... Seems to just make the bass stronger. The amp also has all the little adjustment knobs. They all may as well be labeled in Chinese for me. My biggest overall worry is blowing the new 8", which is a cheap sub since it was the only thing that would fit in that box from Mopar. From everything I have heard about Rockford Fosgate, I assume that amp could fry that sub in its sleep.

 

Rob

[Butchershop]

Per the radio tech info, you are able to adjust the sub output -- both frequency and level. Sounds like you've found the level, now just need to set the pass through filter frequency. An 8" isn't going to boom a lot of bass and I'm not sure if the 'box' you have is tuned or not. But, you can try the three settings and see what sounds best to you. There are various 'in vehicle' factors that make systems sound differently.

In the end, it's your ears that determine the best settings. That said, an 8" sub can add quite a bit to the overall sound quality. Just don't expect to impress these guys!

 

 

Frequency won't blow the sub, but output level will if set too high. Your expectations sound reasonable so I don't think you'll have any issues.

 

Subwoofer Controls: The Kenwood KDC-BT755HD offers the following subwoofer controls, when you are using unit's subwoofer preamp output.

 

Low Pass Filter: The receiver features a built-in Low Pass Filter control for the preamp-output, when the output is set to Subwoofer. You can select from 85 Hz, 120 Hz, 160 Hz, or off.

Subwoofer Phase: You can adjust the phase of the subwoofer output between 180-degrees (Reverse) or 0-degrees (Normal).

Subwoofer Level: Once the Subwoofer preamp output is activated, you can independently control the subwoofer preamp output level (-15 to +15) from the CD receiver.

[knever3]

For the radio you should have used the dedicated RCA outputs that are labeled SUB.  I don't know Kenwood's settings very well but you should have the manual.  Set the sub crossover to 85Hz.  Low pass filter ON.

 

For the amp you should have the button selected OUT for LOW level input aka RCA's.  You'll want to turn the frequency dial all the way to the right or up.  That way it won't interfere with the crossover coming from your radio.  The gain is to match the output voltage from your radio to your amp.  Start with the gain turned all the way down.  After you have the radio settings setup and the sub level all the way up play a CD with heavy bass at a volume that the front and rear speakers can handle.  Next go to the amp and start to adjust the gain till the sub level starts to stress. 

 

You also have a high pass crossover setting on the radio that should be set to 85Hz HIGH PASS.  That way the four small speakers will be able to play louder and not struggle to produce those low frequencies.

 

That should just about cover it.  Now onto the pics!!

[Automan2164]

Butchershop, Knever3, thanks for the input. It's most valuable since I haven't the slightest idea w/ car audio...

 

Ok, it's all in. I cleaned out the back and got it ready for pics, but it got too dark and I haven't finish tied the excess heading back to the sub, so pics will have to wait until tomorrow. Plus, since I wire squad cars as part of my job, messy wires bother me, so I need to clean those up back there.

 

I must say that I think I am doing something wrong... It seemed like the stock sub/amp had a richer sound, but that was also dummy proof as far as settings go. That was a 'Set it and forget it' kinda deal. Here is a copy of the Kenwood audio controls on my HU:

 

  

Display

Description

SUB-W LEVEL*1

–15 to +15 (0): Adjust the subwoofer output level.

BASS LEVEL

–8 to +8 (0): Adjust the level to memorize in each source. (Before making an adjustment, select the source you want to adjust.)

MID LEVEL

TRE LEVEL

EQ PRO (for KDC-X797)

 

BASS ADJUST

   

BASS CTR FRQ

60/ 80/ 100/ 200: Select the center frequency.

   

BASS LEVEL

–8 to +8 (0): Adjust the level.

   

BASS Q FACTOR

1.00/ 1.25/ 1.50/ 2.00: Adjust the quality factor.

   

BASS EXTEND

ON: Turns on the extended bass. ;
OFF: Turns off the extended bass.

 

MID ADJUST

   

MID CTR FRQ

0.5K/ 1.0K/ 1.5K/ 2.5K: Select the center frequency.

   

MID LEVEL

–8 to +8 (0): Adjust the level.

   

MID Q FACTOR

0.75/ 1.00/ 1.25: Adjust the quality factor.

 

TRE ADJUST

   

TRE CTR FRQ

10.0K/ 12.5K/ 15.0K/ 17.5K: Select the center frequency.

   

TRE LEVEL

–8 to +8 (0): Adjust the level.

PRESET EQ

NATURAL/ USER/ ROCK/ POPS/ EASY/ TOP40/ JAZZ/ POWERFUL: Select a preset sound mode suitable to the music genre. (Select "USER" to use the customized bass, middle, and treble settings.)

BASS BOOST

LV1/ LV2/ LV3: Select your preferred bass boost level. ; OFF: Disables level selection.

LOUDNESS

LV1/ LV2: Select your preferred low and high frequencies boost to produce a well-balanced sound at a low volume level. ; OFF: Disables level selection.

BALANCE

L15 to R15 (0): Adjust the left and right speaker output balance.

FADER

R15 to F15 (0): Adjust the rear and front speaker output balance.

SUBWOOFER SET

ON: Turns on the subwoofer output. ;
OFF: Turns off the subwoofer output.

DETAILED SET

 

HPF

THROUGH: All signals are sent to the front speaker. ;
100/ 120/ 150 (HZ): Frequencies lower than the specified value are cut off.

 

LPF SUBWOOFER*1

THROUGH: All signals are sent to the subwoofer. ; 85HZ/ 120HZ/160HZ: Frequencies higher than the specified value are cut off.

 

SUB-W PHASE*1

REVERSE (180°)/ NORMAL (0°): Select the phase angle of the subwoofer output to be in line with the speaker output for optimum performance. (Selectable only if a setting other than "THROUGH" is selected for "LPF SUB-W".)

 

SUPREME SET

ON: Creates realistic sound by interpolating the high-frequency components that are lost in MP3/WMA/AAC/WAV audio compression and iPod. ;
OFF: Disables creation. (Selectable only when playing back an MP3/WMA/AAC/WAV disc, USB device or iPod.)

 

VOLUME OFFSET

–8 to +8 (0) (for AUX) ; –8 to 0 (for other sources): Presets the volume adjustment level of each source. The volume level will automatically increase or decrease when you change the source. (Before making an adjustment, select the source you want to adjust.)

 

I have just been mostly playing so far.

 

I have the level at 9, the LPF at 85HZ, and the preset eq to 'rock'. It just didn't sound like I thought it should, basing it off the stock stuff.

 

I take it the HPF it talks about for the front is the high pass crossover you talked about? So basically, it filters out any bass going to them... What would be your recommended starting point for that?

 

 

You beat me to the controls on the amp, so that saves some questions on my part.

 

I have some more tinkering to do...

Rob

[Automan2164]

So. Just played with it some more... As well as looked into more settings. So far, we are here:

 

HU:

 

SUB LEVEL: +9

LPF: 85HZ

HPF: 100HZ

 

 

AMP:

 

HIGH/LOW: LOW

FREQ: 250

GAIN: 6 (Haven't yet touched it.)

 

Any reason I would need to change the phase?

 

When you talk about adjusting the gain to the point where the sub starts to stress... What am I listening for?

 

I can't get too loud out there because it's now almost 9, so I will have to play more tomorrow.

 

Rob

[Butchershop]

No to the phase change. This reverses the pos/neg wiring to the sub. The sub will be moving in when it should be moving out and the reverse.

 

The frequency setting is for controlling the highest note you want the subwoofer to play. The higher the Hz, the higher the subwoofer will try to play. You can adjust this depending on how well your sub reproduces frequencies at each range.

 

The gain setting determines how much power the amplifier is putting to the subwoofer. Be careful with this knob, turning it up too high can blow your subwoofer out. Adjust it so your subwoofer plays at a reasonable volume.

[knever3]

Yeah that^

[Automan2164]

Was talking to a guy at work who always dabbles in car audio, and I think he sold me on the remote EQ. He brought up a good point about just being able to control it on the fly depending on mood and music. I found it online as cheap as $18, lists for 30.99. I ended up calling the local audio shop that has always given me great advice. I'm going to pay the list price through them and give them a little business.

 

http://www.rockfordfosgate.com/products/details/peq

 

 

Always better to help a good independent business, as well as I am sure they will give me the hands on run down when I pick it up.

 

Rob

[Automan2164]

Going to be a long wait... Audio shop called back today, their shipments only come once a week from the warehouse... And the shipments only come Tuesdays... I said to go ahead and continue the order, but talk about itching to just go to amazon...

 

It helps that they are a good group of guys.

Rob

[Automan2164]

Since I have nothing else to do, here is the page for the el cheapo sub that was the only one that would fit back into the factory spot.

 

http://www.soundstormlab.com/auto/ss8/

 

Rob

[92tanMJ]

$20 bucks that aint too bad..I may have to get one. Ive always wanted to upgrade the speakers in my XJ and add a sub but I never got around to it. This makes me want to put some speakers in my MJ