View Full Version : Which amplified head units allow bridged channels?
11-19-2004, 10:31 AM
Good day folks!
Until a week ago, I had been the happy owner of an old but very reliable kenwood KAC-646 powering a pair of JBL 2 way speakers mounted in the pillars next to the backseats (ear level) and a JL audio powerwedge single 10 inch subwoofer. It was fed by a radio tuner style 10 disc plugged into the stock ford head unit. Nice and stealth. Everything looked stock but the woofer rattled the frame and the ear level mounted 2 ways pumped out crystalline clear treble.
Then the "short" (or whatever it was) happened and it took out my MSD ignition and amp. No problem I said and switched out my amp for a jensen xa2250. Well...that unit turns out doesnt work (someone gave it to me, I guess it was toast when I got it). So now I'm just pissed. This system had been failing off and on for 1/2 a year now. So.....
I want this system as simple as possible to remove points of failure. I'm looking for one of those amplified head units (I am dead set against having a "component" style system) but I am at a loss to find one that claims bridgeable channels. I only need to power 2 speakers + small sub really. Now I have found the new Panasonic CQ-C9800U which _claims_ 4x 70 watts and 4x60 watts rms but I am unsure if that unit is bridgable or if those calims stand up. Otherwise it is all I want: self-amplified, mp3 player, cd player.
Does anyone know of any other decent head unit that allows bridging?
Thanks in advance!
11-19-2004, 11:24 AM
It's simply NOT going to happen. The physical size of CD players limits this, as well with EVERYTHING else they need to fit into the case. Anyways, the most HONEST watts you'll get out of a cd player is about 27watts rms x4 out of something like an alpine v-drive hardwired to your battery. Also, i've NEVER heard of a bridgeable cd-player amplifier...it's been asked b4 and i'm pretty sure they got the same result i stated above.
So, my suggestion is to get a nice alpine cd player, and a small 4 channel amplifier. The external amplifier will give you much better sound b/c it is its own unit instead of being part of a cd-player which is made to do other things as well. Look into a us acoustics 4065, you can get 65x2 RMS and bridge the other two cahnnels for 160x1 RMS. This is your best bet, and you honestly won't know "crystallin treble" or "rattling woofers" until you at least have an external amplifier...you'll e much happier with sound. Oh and by the way, that amplifier is small, it can fit under a seat easily...so you can easily keep it stealth. peace
11-19-2004, 11:48 AM
Hmmm, I suspected as much since I looked high and low for information and could not even come up with a single reference to a birdgeable head unit by part number. I had actually had the speakers themselves powered by the measly stock amp and found that to be quite acceptable for treble (doesnt take much juice to make treble) as long as there was something else pumping up the subwoofer. The amp was just running a single woofer on one channel and it was too much for an open cabin vehicle I thought so an even lower signal baby onboard amp would do quite nicely.
There seems to be some rumors that at one point there were bridgeable head units. I have an external cd player so just a deck with radio capabilities would technically be adequate so disregard that cd player reference. I can work around that. Would you know of the older units perchance?
11-19-2004, 11:52 AM
Some Pioneer can do it, I would definetly recomend an external amp though.
external amp would prolly be cheaper... even if its a crappy small one.
two of those would be quite sick.
Like nosaj070 said...Pioneer cd players can power subwoofers decently for no more than what it is (its not gonna be mind blowing bass but some good bump will come out of it) when u place the sub on the rear speaker output, and then put the settings to the front and sub . then the cd player will only allow low frequencies that a sub needs .
11-19-2004, 02:49 PM
I took a look at the pioneer knowledge base and it seems that they are of the opinion that their units dont bridge. I assume then that the woofer is simply run off the regular rear channel as c0la suggested. Which pioneer units have been "seen" bridgeable? I'd like to go comb through some specs while I wait for code to compile.
Not to sound negative but just so everyone understands where I am coming from: I spent the last 4 months wiring, rewiring and rewiring again my kenwood over and over again because either it would turn itself off or the sound would fade in and out or it would not turn on at all. Then I finally wired it up so none of that happened but got horrible alt whine even though the amp was basically lashed to the battery itself in the "trunk" running right off maybe 3 inch lengths of wire to the posts. Then I put it in the rear 1/4 well behind the plastic all stealthy and it actually worked for 1 whole day before that surge that took out my entire electronics system, ignition box and amp. Last year, my eec-iv ecu burnt out (went carb) and the $250 maf before that. This car has electrical gremlins. The way I see it: Headunit + cd changer + amp means 3 things that can and will, with my bad luck, fail. 1 single headunit could be triple fused, isolated and paranoically protected, switched and the 3 bundles of wires mummified rather than the current 8 bundles + 4 modules.
All bellyaching aside =)
I did some research
That pioneer CQ-C9800U unit does not list RMS but only peak, which leaves me wondering especially after I saw this clip:
which rated the pioneer at 22.4 watts (I assume this is it's true rated continuous power). Plus I read the manual and it seems as if the CQ-C9800U takes only a 15 amp fuse on it's main lead and the draw is "less than 2.5 amps" so it cannot be better than that v-drive which takes a 20 amp fuse (havent researched it yet but I'm getting there they have 27 watts RMS on their better units ). Now I had a look at my kac-646's specs and it was listed as rated 25Wx4channel at 4 ohms at 1 khz .08% distortion or 70W rated 1 khz .8 distortion bridged rear channel. I had been running a single jl audio powerwedge 10 inch woofer (4 ohms I think) on the bridged channel with the gain on .8 out of 3 (not sure what units that corresponds to). I dont know how having than gain turned down equates into these numbers but my gut feeling is that the 70 turned all the way down was painfully loud then the 27 turned all the way up should come close . So the alpines are the most powerful self contained units it seems.
What bad things happen if you put both rear + speaker leads and both - speaker leads together? Less amp draw?
11-19-2004, 04:46 PM
And our finalists are....
The alpine CDA-9833 (26 rms)
The Pioneer DEH-P8MP (27 rms draws 20 amps so I believe it)
and the CQ-C9800U but this last one is a phenomena. There dont seem to be any reivews on it anywhere except for one done by crutchfield where they didnt do anything other than say it "sounds good" and that one pic I found. Has anyone seen , heard anything about this unit? It uses some kind of new digital amp (T-class?)
11-19-2004, 05:00 PM
I'm looking at the manual for a Pioneer DEH-P760MP, and it says 22wrms, 50w x 4 @ 4-ohm, or 50w x 2 @ 4-ohm and 70w x 1 @ 2-ohm for subwoofer, I don't how you would have to wire the sub though.
11-19-2004, 06:51 PM
I would recommend just gettin a decent deck since your not handling too much in your car. Also get a 4 channel amp and use 2 and 1 bridged. Im pretty sure that will be 2x to 3x louder than your old setup because of the HU and also that 646 is kinda of an old amp not pushin too much. Get a good Alpine deck. Since it looks like you dont really want to spend to much a CDA-9815 - CDA-9827 would be good and since you like Kenwood amps get a KAC-8401. Im not sure of the specs on the speakers you listed but I highly recommend spending a little bit more to get an amp that powers them close to full power because if at any time you feel like the amp you get isnt enough, you basically wasted money because I doubt somone will give you the amount you paid for it.
11-20-2004, 03:58 PM
Now this is wierd. I put back the factory amp (only one left: painless clip clip to oem connectors) and kept the rf style cd player. I noticed that my rear jbl speaker was like a squeeky whisper and the right had a little bass but not much. Confused, I hopped inside and grabbed the old factory speaker on a hunch. It easily made 3 times as much bas. Thinking that speaker must have been damaged, I changed the other one for laughs. I'll be...... the stock cardboard 13 years old factory oval speakers work better than the $70 pair jbls! The jbl's had no rips/tears or any damage on them. With all 4 speakers factory, I noticed that it was backwards: the bass was coming from in front from the doors and the treble/midline coming from the back.
I got to thinking that this setup has potential. Didnt they make some pancake woofers a while back? Fit those to the door speaker mounts and a set of treble/midline speakers in the back with an alpine giving each one a nice 27 watts. And then I get my trunk back!
Hows about that? Anyone know which pancakes might fit in the door of an 87-93 mustang? It needs to be quite low profile.
11-21-2004, 06:18 PM
who da man? I just resurrected my old kenwood amp! She lives again. I opened the jensen and it was charred black inside. Tossed. I opened the kenwood and there was a only single tiny area of the breadboard burnt out where about 4 traces came together. I attached a wire to bridge the gap and the little triangle lit back up! It's aliiive!
Boom-ch boom-ch <scratching noises>
But now I wanna experiment with my dual 6 inch miniwoofers in the door idea.
With the case off, I have to wonder: Wouldnt the amp cool better with the top open or maybe even caseless? I can attach a small open cage style shell around it and suspend it under my hollowed out dashboard. What do you all think?