View Full Version : KDC-BT945U volume drop after a period of time

09-07-2011, 01:56 AM
Sorry for the long post, but would really appreciate opinions and guidance.

My current setup:
Kenwood KDC-BT945U (bought off ebay as mfr refurb)
- HU amp off
Kenwood 4 channel amp KAC-9452 (70w rms x 4 @ 4 ohms)
Polk Audio DB571 front (100W rms max, 4ohm)
Polk Audio DB691 rear (100W rms max, 4ohm)
Factory speaker/power wire.

Before buying the amp:
Setup/install went without issue. Have installed 10+ HU's over the years. Blue-tooth works great, USB jump drive works great, sound quality is phenomenal.

Running at 70mph with the windows down requires a decent amount of volume to get sound worth listening too. I listen to a lot of metal (ozzy, metallica, puddle of mud...), so the louder the better. After about 10 minutes or so of running at 25/35 (USB as source), the volume drops dramatically and crackles. I turned it down for a minute, rolled up the windows, turned it back up to 22 and it was all good. Bumped it up to 25 again and it dropped the volume again within a few minutes.

After buying the amp:
Figured I needed an amp to push the polks. In comes the KAC-8452 (70w rms x 4). Have best buy install it with a kicker AWG 4 power wire and twisted pair RCA's along with a 3rd set of RCA's in case I wanted to throw in a sub later. I haven't run an amp since I was a teen (15 years ago or so), so I figured I'd let someone else deal with crawling around and installing stuff. Did a great job with the install, also ran new heavy wire to the front doors and rear deck for the speakers.

Readjusted all the EQ settings and whatnot on the HU, shut off the internal amp, turned the low end boost off, adjusted the low end of the EQ to sound good when loud so I could bump it up when I have the volume down and windows up. Pounds hard, sounds awesome after some further tweaking of the EQ.

Rolling along this morning (first hour long commute after install of amp), volume at 25, sounds great, hitting hard... volume drops out...

So... Love the features, used to the features (playlists are a must), have run kenwood HU's for years... contemplating setting it on fire.

My last HU was a KDC-X693 running a cheaper set of pioneer 5x8/6x9 speakers. I could consistently run it about 3 points from max for extended periods of time without issue. I figured I'd bump up the quality and feature list a bit so I could have a blue-tooth speakerphone (which works great). Only to end up with something that can't even power it's low level outs? What's going on here? Did I get a dud? Is there a setting I'm missing?

I upped the gain on the amp to about 90% on both front/rear channels (was at about 40%) and the HU runs at about 22-24/35 and it's loud and sounds great. But I can't shake the feeling that I'm on the verge of something melting down in the dash of my car.

I know the volume issue was discussed int he past, but they were pretty old threads and I didn't see any make mention of my HU directly.

Was looking at a KDC-X995 and just consider my 3 week old 945 a lost cause... but afraid I'll have the same issue since the "kenwood" logo is still on it... lol. I just really like the playlist feature and the fact that I have software that builds playlists very easily out of my folder structured music library.

Do I just cut my losses and look for a new head unit that does what I want or what do I do? Is there something I'm overlooking?

09-20-2011, 12:29 AM
I have adjusted my amp gain to be just high enough to not distort with the HU volume at 30. It will run about 30 minutes like this, then the automatic volume drop happens again. I'm going to try and pull teh HU out and wire in a typical mp3 player using RCA Y cables so I can run all 4 channels of the amp. Not sure what I'm hoping for at this point. I know the HU can't drive the speakers directly without the volume drop, I guess all I can do is try to push the amp/speakers without the HU to see if the amp does what the HU internal amp does.

09-20-2011, 01:00 AM
Well I run a Kenwood HU and don't have a problem with anything of that sort, I can play it at 30 all day.... But your gains are at 90%??? You might wanna start there bro, that's ridiculously high.

09-20-2011, 01:59 AM
I have adjusted them since my first post. they are now around 50% and after about 30 minutes of running around 31 on the hu, the volume still drops about 25%. at first, the volume fluctuates up/down, then about a minute later, it drops 25% or so and stays there. Then if I turn the hu to max (35), the volume does go up and sounds just as good as it did before it dropped on its own.

I run a Kenwood as well in my other car and I never had this issue. I just run the speakers directly off the hu without an external amp at all.

09-20-2011, 03:16 PM
Strange:\ I don't have enough experience to really offer much help, hopefully some of the most experienced guys can help though. All I could suggest is make sure all your connections are well and proper.

09-20-2011, 08:32 PM
did you ever get this issue figured out? i have been battling this god awful issue for over a year now. i have 2 JL speakers in the front doors and 2 kenwood speakers in the back.

originally i bought the headunit and the 2 front speakers (kenwood) at the time because i did not have enough to buy the back 2 speakers. issues started happening pretty much on my way home from the stereo shop. i went back and forth with the shop and they cant find anything wrong. i found if i faded the sound heavily +/- 9 to 12 to the front or the back the issue didnt seem to happen and i could crank the volume up to compensate for not having all 4 speakers bumping. i figured the back 2 OEM speakers could be the problem.

so i bought 2 jl speakers and put them in the front and put the kenwoods in the back. still had the same issues, tried fading to the front and the back and could crank it up pretty loud with no issues.

at this point the shop decided the head unit might be bad so i took it out and shipped it to kenwood with a long explaination of the problems going on with it and they sent it back saying there were no issues found with it. so the shop put in a temporary replacement for the time being to see if that would help and it didnt, the problem persisted.

AT THIS POINT where i am at now, the shop decided to put the OEM speakers back in and see if the speakers i put in were the problem. after going back to oem speakers i am STILL having the same problem after hitting about 20-22 volume level. it sounds like **** and even sounds worse when the volume drop and fuzziness kicks in.

ive taken this thing to multiple shops and they all say everything is good, the wiring the speakers the head unit the connections are all good. why wont this thing perform as normal????

i am so pissed off at this thing it makes me want to get rid of my truck. all i want is to have some decent sounding audio. can anyone please shed some light on this problem iam having?

09-21-2011, 12:30 AM
did you ever get this issue figured out? i have been battling this god awful issue for over a year now. i have 2 JL speakers in the front doors and 2 kenwood speakers in the back.

I'm wondering if your speaker wiring is out of phase. +/- do matter, but from personal experience, polarity is only relative to polarity of the other speakers. Since yours seems to sound better faded towards front or rear, that suggests your front is out of phase with your rear. When I installed my speakers, I should have paid close attention to the car color vs polarity of what plugged into it so I could have all my speakers wired 100% accurate. Or I should have picked up the OEM plug adapters for the speakers, which I completely forgot when at the store buying the HU install kit/plugs.

IME, when they are out of phase, volume seems low and sounds come out hollow with no richness.

Try fading 100% front with the volume at a decent listening level, not cranked. With 100% front, fade full right and listen. As it fades, does it start to sound a bit hollow or does it sound more rich/clean? Fade left, listen for the same. Go back to center and listen. When at center does it sound full/rich? If so, then your fronts are more than likely in phase properly with each other.

Do the same, but fade 100% rear. Go right/left and listen. If it sounds rich on center, then I'd guess your fronts are out of phase with your rears.

If all that checks out, swap the polarity on either both fronts or both rears and try the process again. Essentially, a process of elimination. You could have it wired 100% accurate regarding polarity for front/rear, but maybe you have a fluke in the car wiring with one of the pairs flipped.

Hope you can sort out your issue.

As far as my issue, since I bought my stuff on ebay, I can't really send any of it in to get it fixed without paying a premium I'm sure. Considering what I spent on the HU and amp, I'm not out a lot. The installation fee for the amp (labor and all wiring, 4 gauge power, 3 rca pairs) cost as much as the HU/amp combined! lol ($216 install, $225 HU/amp via ebay)

I have yet to come across anyone that has my issue when using only the preouts and the internal amp off in the HU. Everyone I've come across that were having issues were using the internal amp.

Even still, I ran across a few posts on various forums where power to the amp was the issue. So, after I got home tonight, I started to look at my wires in the trunk. Upon checking the ground connection that the installer made, I realized he used a self tap screw into the thinnest piece of metal back there. The screw also would not tighten as it seemed stripped. So, bad connection number 1. Since I don't have hardly any spare wire (about 2 feet of ground/3 feet of hot from the kicker install kit the best buy guy used), I had to find somewhere that was at least double thickness tin to screw it to. After wigging things around a bit, the hot terminal came off the cable tied to the amp. Upon further inspection, I noticed they did not solder the terminals on the ends of the power or ground wire, they were just crimped, and obviously not very well. So, I pulled the ends off the ground and hot, put a new ends on the longer piece of ground I had so I could reach somewhere useful. I then used a heavy 1/2" bolt/nut (vs self tap) through a double thick support in my trunk for my ground. Bad connections 2,3 and 4 resolved. When unscrewing the terminals from teh amp, I also realized that both hot/ground were not tight. Bad connections 5 and 6 resolved.

So, basically, my entire power source was poorly connected and poorly grounded.

I'll run it hard tomorrow and see if it still fades out on me after 10-15 minutes. That is if I wake up without the headache I have at the moment...

If it is still not resolved, I'll plug an mp3 player directly to the amp and take the HU out of the mix. If it still does it, then I know I have more than one issue. I know the HU has issues when using the internal amp. If the amp has issues using an mp3 player, then it's also crap.

Hopefully by the end of this weekend, I'll have at least trouble shot the issue(s) as I'm taking a day off. If so... back to ebay I go. Will just find places that offer at least a 10+ day warranty directly and make sure to install quickly and push it hard right away.

09-21-2011, 11:43 PM
Well, wasn't a bad power connection at the amp... volume still drops on it's own.

09-23-2011, 07:40 PM
Also is not the HU... I disconnected the HU today and connected a mp3 player to my amp using splitters so I could drive all 4 channels. After about 15 minutes, the volume drop happened again repeatedly just like the HU did.

So, since my issues first presented with only the HU and speakers (no amp), do I then assume that the speakers are doing something wonky? Like changing ohms on me as they heat up after some use? I could see that causing a volume drop... A short would obviously drop the sound, but would drop it completely in a channel, in my case, all 4 drop similarly as far as my ears can pick up. Not a specific frequency, just the volume seeming to go down.

Or, do I just assume that kenwood's amps aren't able to supply enough power (unless I drop more cash on their excelon series) or find one of their others that puts out more than the one I have...

This is a very strange problem to me.

What makes it more strange, with just the HU, the speakers would go loud, then the volume would drop and crackle badly. With the external amp, the speakers don't crackle at all, only a volume drop. If I turn the HU up further (with the amp), they get as loud as they were before, or pretty close regarding where I have my gains on the amp now set. There is a fine line where it just constantly fluctuates. If I keep it couple ticks below where it drops, it will run like that for over an hour without any issues. If I turn it up a couple ticks to the point where it drops, it fluctuates up and down about the equivalent to 7-8 ticks on the volume knob. If it drops and I jack the volume up, it will run loud and not drop out on me.

Now, in hindsight, if I paid retail for this stuff, I'd be livid. However... if I paid retail for this stuff, I'd be returning it.

At least I ruled out the HU... I really like this model as it seems kenwood dropped streaming BT from their newer models due to complaints of poor audio quality. Personally, I like being able to stream talk radio over my phone to my HU... so the sound quality isn't an issue.

Anyway, it seems not many people have my issue or know a resolution and this thread is more or less my place to keep track of what I've done. So I don't repeat a step.

10-14-2011, 01:00 AM
well my issue im having is with a kenwood excelon 494 unit so dont go dropping money on it either.

im having more or less the EXACT same issue as you.

following my first post, just to reiterate i have tried the following combinations

new head unit + new speakers

random head unit + new speakers

new head unit + original speakers

the only thing i have not tried is original head unit and original speakers. the only thing i can think of at this point besides that is that there is a power issue with the alternator (more on this later) or may need all new wiring from the battery all the way back to the head unit and speakers, or possibly a capacitor (have NO idea why i should even need one just to power 4 gd speakers)

the reason why i say the alternator might be an issue is because i had a weird check engine light come on the other day and i had it read at the car repair shop. i forgot what the code was but it had something to do with rear abs speed sensor. i looked it up and came across some chrysler forums where a bunch of jeep/dodge guys were getting some weird codes thrown from time to time and they said that they get weird codes sometimes when they have unsteady voltages running through the truck. i had the car repair shop clear the code out and the check engine light hasnt came back and its been a few weeks. also even a few months prior to this last code that was thrown i had another check engine light but it happened in the middl eof the night and it disappeared by morning time and i never got a chance to get it read.

anyways i am so **** sick of this prob i want to poke my eyes out.