db651s cutting out
lebowski
Posts: 4
So here's the current setup
HU: Pioneer DEH2200UB
amp: Kenwood KAC8405 60x4
front: Polk db651s
rear: old unknown JL 12" sub
I have some 6x9s on the way that I'm gonna hook up to the amp but currently the front channels go to the db651s and the rear ones are bridged to the subwoofer.
Here's the problem: my head unit only has one pre-out and it's 2.2v. The amp has 2 RCA inputs so I split the signal into the 2 channels, meaning each is now only getting 1.1v.
I managed to adjust the gain on the amp channels to make it sound decent at low volumes but anything more than moderate levels makes the speakers cut out and return a second later with a slight fade in. My first thought was that the front speakers had a overload protection that cuts power to them if they're overpowered (speakers handle 55w RMS, amp is 60w, not a huge deal right?)
But then there is the possibility that the amp was doing the same thing. I don't know how much power that sub wants, or what condition its in internally, could it be causing the intermittent sound loss?
This amp also has speaker-level inputs (optional for HUs that don't have pre-outs). My head unit puts out 14w RMS per channel, so I was thinking this is probably a better signal for my amp than a 2.2v signal that has been split, right? I'll probably try that next and adjust gain accordingly to see if it helps.
HU: Pioneer DEH2200UB
amp: Kenwood KAC8405 60x4
front: Polk db651s
rear: old unknown JL 12" sub
I have some 6x9s on the way that I'm gonna hook up to the amp but currently the front channels go to the db651s and the rear ones are bridged to the subwoofer.
Here's the problem: my head unit only has one pre-out and it's 2.2v. The amp has 2 RCA inputs so I split the signal into the 2 channels, meaning each is now only getting 1.1v.
I managed to adjust the gain on the amp channels to make it sound decent at low volumes but anything more than moderate levels makes the speakers cut out and return a second later with a slight fade in. My first thought was that the front speakers had a overload protection that cuts power to them if they're overpowered (speakers handle 55w RMS, amp is 60w, not a huge deal right?)
But then there is the possibility that the amp was doing the same thing. I don't know how much power that sub wants, or what condition its in internally, could it be causing the intermittent sound loss?
This amp also has speaker-level inputs (optional for HUs that don't have pre-outs). My head unit puts out 14w RMS per channel, so I was thinking this is probably a better signal for my amp than a 2.2v signal that has been split, right? I'll probably try that next and adjust gain accordingly to see if it helps.
Post edited by lebowski on
Comments
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Don't mean to be curt or rude, but here are the issues in sequence from your post and yes Skip is right, your amp is going into protection.
1. One pre-out means you're getting a full range signal from whatever the default hpf on the hu is. Now splitting this signal to run the sub means the sub is also playing the range meant for the components. Defeats the purpose of running it.
2. Not a big fan of splitting any wire carrying the signal. It will degrade the sound. But this is a minor issue here.
3. If you set your gains, to have decent decibels at low volume, you set them too high. Set your gains at about 80% of max volume at the hu. Turn the gains all the way down, set the volume to 80% now turn the gains up till you hear distortion and then back off a bit. That is your max safe volume.
The way you have them setup, the amp is already close to its max power when you have volume low. Now when you crank it a bit, the amp would be pushed to making more power than it safely can and would go into clipping and eventually into protection by cutting off. The amp is cutting off not the speakers.
To give you an idea, max volume on my hu is 63. When its loud (well, relatively at least) the volume is at 50. Around 20-25 one really doesn't hear very much, more so if I'm driving. Then again, I may just be going deaf
. This is just to give you an idea.
I'd just use the single pr-outs to run the db's and forget about the sub till you have a hu that lets you run one. -
It sounds like your amp is going into protection.
What ohm load is being presented to the amp by the sub? If its 2 ohm, most 2/4 ch amps can't handle that bridged, including that Kenwood.
Turns out it was a wiring issue that I guess was making the amp gointo protection mode. The sub is 4ohm -
Don't mean to be curt or rude, but here are the issues in sequence from your post and yes Skip is right, your amp is going into protection.
1. One pre-out means you're getting a full range signal from whatever the default hpf on the hu is. Now splitting this signal to run the sub means the sub is also playing the range meant for the components. Defeats the purpose of running it.
2. Not a big fan of splitting any wire carrying the signal. It will degrade the sound. But this is a minor issue here.
3. If you set your gains, to have decent decibels at low volume, you set them too high. Set your gains at about 80% of max volume at the hu. Turn the gains all the way down, set the volume to 80% now turn the gains up till you hear distortion and then back off a bit. That is your max safe volume.
The way you have them setup, the amp is already close to its max power when you have volume low. Now when you crank it a bit, the amp would be pushed to making more power than it safely can and would go into clipping and eventually into protection by cutting off. The amp is cutting off not the speakers.
To give you an idea, max volume on my hu is 63. When its loud (well, relatively at least) the volume is at 50. Around 20-25 one really doesn't hear very much, more so if I'm driving. Then again, I may just be going deaf. This is just to give you an idea.
I'd just use the single pr-outs to run the db's and forget about the sub till you have a hu that lets you run one.
1. I have the signal going to the sub low-pass filtered (there's hi/low on each channel so I have high-pass on the front channel), so even though the RCA input is the full range the sub is only getting its effective range, did I understand what you were trying to say correctly?
2: Unfortunately without upgrading the head unit I have to or I can only use half of the amp
I've got the gain set roughly for both channels and it sounds good. Honestly the sub was never part of the plan (and won't be included once my 6x9s come in), just wanted to see how it would sound since it was sitting in the garage unused.
I'll try plugging the un-split RCA signal into the db651 channel and see if it improves it at all.
One more question while I'm posting.... Any estimates for a frequency for the high-pass on the db651s? It's a 12 db/octave slope, maybe 100-200hz? They're rated down to 50hz but I don't expect much from a 6.5" that low. And the low-pass for the sub should probably be somewhere near the same frequency right? Once I get the 6x9s (Alpine Type S) I'm gonna turn the filter off that channel and give them the whole range, keeping the front 6.5s high-pass filtered. -
1. I have the signal going to the sub low-pass filtered (there's hi/low on each channel so I have high-pass on the front channel), so even though the RCA input is the full range the sub is only getting its effective range, did I understand what you were trying to say correctly?
No. At your hu you cant set lpf/hpf seperately. Hence there will be a default hpf at a fixed slope builtinto the hu. Typically this is in the 80-100hz range. So the signal from the preout is 80hz and above. Now at the amp you are setting LPF at say 80hz which means the amp is sending everything 80hz and below to your sub. So what is your sub getting?2: Unfortunately without upgrading the head unit I have to or I can only use half of the amp
Yes.I've got the gain set roughly for both channels and it sounds good.
If you're setting the gains for loudness at low volumes, you either need to reset your gains, or ensure that you never crank the volume knob. Cause if you do, you will eventually blow your speakers / amp.Honestly the sub was never part of the plan (and won't be included once my 6x9s come in), just wanted to see how it would sound since it was sitting in the garage unused.
A 6x9 will never make up for a sub. Instead of investing in 6x9, I would rather upgrade the hu for a start. Then maybe look to upgrade the 651's to set of components.I'll try plugging the un-split RCA signal into the db651 channel and see if it improves it at all..
Chances are the sound from the db's will be a lot cleaner.One more question while I'm posting.... Any estimates for a frequency for the high-pass on the db651s? It's a 12 db/octave slope, maybe 100-200hz? They're rated down to 50hz but I don't expect much from a 6.5" that low. And the low-pass for the sub should probably be somewhere near the same frequency right? Once I get the 6x9s (Alpine Type S) I'm gonna turn the filter off that channel and give them the whole range, keeping the front 6.5s high-pass filtered.
The 651 is splitting the signal between the mid and the tweet around 2khz. Everything below this goes to the mid and above this goes to the tweet. The low end of the mid is set at the hu. Since you can't set this manually there is obviously a default setting within the hu, I refered to this in an earlier point as well. You can also set the hpf at your amp. I'd set it at around 50-80hz. -
No. At your hu you cant set lpf/hpf seperately. Hence there will be a default hpf at a fixed slope builtinto the hu. Typically this is in the 80-100hz range. So the signal from the preout is 80hz and above. Now at the amp you are setting LPF at say 80hz which means the amp is sending everything 80hz and below to your sub. So what is your sub getting?
The low and high pass filters are on the amplifier, I didn't mean I was going to set it from the HU. I'm not sure what the low end of the frequency range is from my HU RCA pre-outs, but with the sub hooked up and low-pass filtered, it is definitely getting signal and power and bumps pretty hard.If you're setting the gains for loudness at low volumes, you either need to reset your gains, or ensure that you never crank the volume knob. Cause if you do, you will eventually blow your speakers / amp.
A 6x9 will never make up for a sub. Instead of investing in 6x9, I would rather upgrade the hu for a start. Then maybe look to upgrade the 651's to set of components.
I turned the gain all the way down on both channels, turned up the HU to just before distortion (about 80% of max volume) and then adjusted gain to just before distortion.
I definitely don't intend for the 6x9s to make up for the sub, to be honest the sub was never part of my sound system plans, just a placeholder while I waited for the 6x9s to ship, and I'll welcome the extra sound range I get when I put in the 6x9s in place of the sub. I don't typically go around listening to hip hop at full volume and vibrating my license plate off, I'd rather have high-quality sound at all volumes for any genre of music. I've spent all the money I'm willing to on the system so far, so I'll have to make do with this head unit (and no component speakers...) for the time being.
Thanks for the help so far, things have improved so far and I'm about to replace that **** old sub with some 6x9s in a few minutes...
