The ask Tin about audio thread

Question for the Audiofather (Tin) I have a Velodyne ULD-12 date code stamped on the amp and power servo is Oct of 1994. If I run the servo anywhere form 50-85% gain I get a popping noise when the bass hits. I have hooked it up to a 5.1 system by line level input and and the RCA cable through the subwoofer pre-amp outputs and it does it both ways. However if the servo is below the 50% gain mark there is no popping but the bass is so quiet that it is not there. Also if the servo is over 85% the popping is gone and there is no distortion but there is so much bass it drowns out the rest of the system. Is the amp over or under powering the sub? I have inspected the sub and no visable damage is present and the voicecoil and surround are all intact and connected. I have tried different RCA cables thinking maybe it was a signal problem but that all checks out.

Do you have any ideas of where to start next?
 
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Sounds like the contacts in the knob may be dirty. Potentiometers always corrode over time, they just need to be sprayed with electronic contact cleaner and worked back and forth a bunch of times to break the corrosion free. You can pry the knob off of the potentiometer with a couple of spoons. Put one on either side and pry, should pop right off. Should work fine afterward.
 
upgraded to this JL amp.
http://www.crutchfield.com/S-l4293kB8XZQ/p_136JX3604/JL-Audio-JX360-4.html

I am running CDT CL61 speakers - they're 90w RMS components.

Initially I left in my 8 gauge wiring kit that I had with the old Sony amp that I replaced. I had it grounded to the seat stud. I ran it like this for a couple of days and the sound quality was amazing but the amp gets super hot. I am running the amp bridged and the gain on the amp is set to about 50%, so roughly 80w per speaker.

I upgraded to 4 gauge wire and the amp is still getting hot. I thought maybe my ground wasn't any good, so I rerouted the ground here underneath the center console. It is an existing ground location:
20150421_201911.jpg

amp is still hot.

Is this not a good ground? What other problems could it be? Head unit is a kenwood ddx8901 and i only go as high as 28/35 on the volume.

I am stumped.
 
raroz28 said:
upgraded to this JL amp.
http://www.crutchfield.com/S-l4293kB8XZQ/p_136JX3604/JL-Audio-JX360-4.html

I am running CDT CL61 speakers - they're 90w RMS components.

Initially I left in my 8 gauge wiring kit that I had with the old Sony amp that I replaced. I had it grounded to the seat stud. I ran it like this for a couple of days and the sound quality was amazing but the amp gets super hot. I am running the amp bridged and the gain on the amp is set to about 50%, so roughly 80w per speaker.

I upgraded to 4 gauge wire and the amp is still getting hot. I thought maybe my ground wasn't any good, so I rerouted the ground here underneath the center console. It is an existing ground location:
View attachment 76149

amp is still hot.

Is this not a good ground? What other problems could it be? Head unit is a kenwood ddx8901 and i only go as high as 28/35 on the volume.

I am stumped.
Click to expand...

This is a class a/b amp they do heat up. You are saying hot. Is it hot to the touch or shutting down/ loosing sound? Where is the amp mounted? What ohm load are you getting with dvom connected to speaker leads at e amp. ( disconnect the leads from the amp to test.) You can also back probe the power input to the amp while its playing note if your dropping voltage.

Low ohm load can drive heat, voltage drop will as well, proper amp ventilation is a requirement. * might be normal if your not having sound issues or smells.
 
Ok, so here is my question...Car Audio......

What is everyone doing with the 2013-2014 F150 4.2" LCD headunit as far as swaps? I know Metra makes a kit but I think it looks like crap. All of the HVAC is integrated into the head unit bezel and a lot of people are having issues with anything aftermarket due to the Sync.
 
Krazy-K said:
What ohm load are you getting with dvom connected to speaker leads at e amp. ( disconnect the leads from the amp to test.)
Click to expand...

That only measures the voice coil impedance. Impedance isn't constant, and will fluctuate wildly through the frequency band. Impedance is usually highest at Fs (cone resonance frequency). The cabinet has a lot to do with it as well. A cabinet not properly matched to the driver will alter the factory impedance curve, which puts added stress on a lower powered amp or an amp with a poor power supply. If the cone has to move more air than it was designed to, it can bring a lesser quality amp to it's knees, bottom out the voice coil, or both.
 
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That JL shouldn't be getting hot at a 4 ohm load. Give more details on the speakers you're running and if they have an active crossover inline.
 
raroz28 said:
It gets really hot. Doesn't shut down, but it will burn your hand. The amp is on the floor in the backseat.

These are the speakers
http://www.amazon.com/CL-61-Audio-Component-Speakers-System/dp/B00FX9SO74

How hot should this amp be getting? You said a/b runs hot. Maybe I'm just being paranoid but it is HOT.
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I noticed the ad on Amazon says 2 ohm optional, are you running them at 2 or 4 ohms? Is your amp stable for low impedance loads like that? 2 ohms will make the amp put out around twice the power it does at 4 ohms, and add more heat. Are you getting any clipping? If you had any clippping, you'd know right away...it sounds about as good as nails on a chalkboard.
 
Tin said:
I noticed the ad on Amazon says 2 ohm optional, are you running them at 2 or 4 ohms? Is your amp stable for low impedance loads like that? 2 ohms will make the amp put out around twice the power it does at 4 ohms, and add more heat. Are you getting any clipping? If you had any clippping, you'd know right away...it sounds about as good as nails on a chalkboard.
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I did not take any steps to run them 2ohm. Just ran the speakers to the crossover and crossover to the amp.

I thought that by default they are 4ohm
 
How does it sound? Anything strange? I did some looking around on your amp and many complain about the heat output and mention the heatsink is undersized for the unit. Figured I'd throw that out there.
 
Tin said:
How does it sound? Anything strange? I did some looking around on your amp and many complain about the heat output and mention the heatsink is undersized for the unit. Figured I'd throw that out there.
Click to expand...

hmm good to know about the complaints. surprised though especially with the gain so low, thats why I assumed ground.

What do you guys think of that ground?

And the sound is amazing. I have never been so happy with my system.
 
Tin said:
That only measures the voice coil impedance. Impedance isn't constant, and will fluctuate wildly through the frequency band. Impedance is usually highest at Fs (cone resonance frequency). The cabinet has a lot to do with it as well. A cabinet not properly matched to the driver will alter the factory impedance curve, which puts added stress on a lower powered amp or an amp with a poor power supply. If the cone has to move more air than it was designed to, it can bring a lesser quality amp to it's knees, bottom out the voice coil, or both.
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Tin, I was just looking for the baseline be 2ohm or 4 ohm load. As you noted the amp is known to run hot. Cabinet gain over frequency is a variable that is fun to play with. I'm a former db drag guy. Cabinet design is a crazy art I have only scratched the surface of. I have lots of learning to do.
 
Krazy-K said:
Tin, I was just looking for the baseline be 2ohm or 4 ohm load. As you noted the amp is known to run hot. Cabinet gain over frequency is a variable that is fun to play with. I'm a former db drag guy. Cabinet design is a crazy art I have only scratched the surface of. I have lots of learning to do.
Click to expand...

Cabinet design is fun. Lots of software out there to simulate response. A good free one is WinISD, you just input the T/S parameters and go from there, pretty good stuff. If you want more elaborate designs like quarter-wave tubes, transmission lines, and horn enclosures, the Martin J King Mathcad worksheets are the golden standard.
 
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