Now that my door panels are back together and wired correctly, I’ve moved on to hooking up my stereo and have an amplifier problem that I just can’t figure out. My current system is:
- Kenwood KDC-MP208 Head Umit w/ 2.0V RCA pre-outs
- Pyle PLG6C 6” / 0.5” Component system with 2-way passive crossovers. The 6” speakers are 400W Peak @ 4ohms and 200W RMS @ 4ohms. The 0.5” Tweeters are 100W Peak @ 4ohms and 50W RMS @ 4ohms.
- Pyle PL8 8” subwoofer in a custom box in the passenger footwell. The sub is 400W Peak @ 4ohms and 200W RMS @ 4ohms.
The car came with an 8-channel A/D/S 840.2 amplifier that was WAY overkill for my simple 3-channel system (the PO had it wired to include the center speaker). I sold the amp and replaced it with my trusty old Alpine 3527S 4-channel amp that has been in 4 of my previous cars. It has always been rock solid and reliable. The amp specs in 3-channel mode are:
25W x 2 @ 4ohms
75W x 1 @ 4ohms (bridged)
Input sensitivity = 100mV to 2000mV (500mV at center detent)
I wired the two 25W channels (1 & 2) to the component speakers using the passive crossovers. I bridged channels 3 and 4 to create a single 75W channel for the sub. I double-checked all wires to ensure correct connections. The amp is grounded directly to the battery negative terminal. After checking all connections, I switched the HU on and tried to set the amp gain. I turned both gains down to minimum (100mV) and the HU volume to 30, which is 75% of max. I put in a good rock CD and before I even touched the gains, the amp started to get really hot to the touch. Suddenly, the music cut out and I noticed the amp status LED turned from green to red, indicating the self-protection mode was engaged. I turned the HU volume down to 20 and the green light came back on and the music came back fine with no distortion. The amp was VERY hot though, which is unusual, as this amp has never gotten more than lukewarm in my past installs, even with the tunes cranking.
I hopped online and googled the issue and found several possible explanations. One was a speaker wire short, but it didn’t fit my problem since the amp runs in the green at lower HU volume levels. Some suggested a ground issue, but again it doesn’t fit my problem, since the amp runs fine at low volume. The issue that seemed to fit my symptoms best was a gain problem, in that the input voltage (2.0V or 2000mV) was not the same as the amp gain (currently 100mV). They suggested to set my gain with a multimeter on the speaker terminals to ensure that the input values matched.
I started with the sub channel. I set the HU back to 30 volume and put in a 100hz test tone. According to the chart supplied by the audio forum, 75W @ 4ohms should read about 18.5V on the multimeter at 75% of max volume. I gradually turned up the gain on the sub channel until it was reading 18 volts. At this point the amp was staying in the green, but was pretty hot. I then moved onto the component channels. At 100mV gain, the multimeter didn’t even twitch. As I turned the gain up to max, I got about 6V on the meter at each channel. Still, there was no clipping and the amp was in the green. The 100hz test tone was so loud in the car however that I got worried I was going to blow out the speakers. I took the test tone out and inserted my rock CD and turned the HU volume down to 20 again. The music was clear. As I turned it up past 25, bam it went back into self-protection mode.
I went back inside puzzled and googled for further answers. The best I could find suggests that I’m asking my little Alpine to do too much. I have 2 tweeters at 50W RMS, 2 woofers at 200W and a sub at 200W, which is 450W total @ 4ohms. At the higher volume levels, it seems the Alpine just can’t feed enough watts to drive the speakers. I am confused however because I always thought the RMS and Peak ratings told you the maximum level the speaker could tolerate and did NOT reflect the amount of power required to drive the speaker. I thought that by using my low-power Alpine, I would protect my speakers by staying under the max watt limits. But, given my issue, do I need a more powerful amp? Is that why the Alpine does fine at lower volumes but cuts out and overheats when it gets loud? Do the RMS power ratings really tell you the amount of power you need to drive a speaker?
My confusion is enhanced based on my earlier systems. There, I used an Alpine HU to drive the front speakers and the amp bridged into two 75W channels to drive two 6x9 Boston rear speakers rated at 140W RMS. The amp never cut out even at extreme volume and never got more than lukewarm in that config, with gains set to nominal (500mV). That system could shake the car and not even blip. But, I was only using the amp to feed 150W into two channels totaling 280W.
So, I’m stuck and the trunk of my NSX is littered with wires and components until I figure this out.
Is my amp broken, or am I asking it to do too much? Should I just buy a more powerful 4-channel amp? Why does it get so hot and clip/cut out at low gain levels- I would think that it should do the opposite, since it is a low-power amp. Is it trying to overdrive itself?
Any help would be greatly appreciated!!!
- Kenwood KDC-MP208 Head Umit w/ 2.0V RCA pre-outs
- Pyle PLG6C 6” / 0.5” Component system with 2-way passive crossovers. The 6” speakers are 400W Peak @ 4ohms and 200W RMS @ 4ohms. The 0.5” Tweeters are 100W Peak @ 4ohms and 50W RMS @ 4ohms.
- Pyle PL8 8” subwoofer in a custom box in the passenger footwell. The sub is 400W Peak @ 4ohms and 200W RMS @ 4ohms.
The car came with an 8-channel A/D/S 840.2 amplifier that was WAY overkill for my simple 3-channel system (the PO had it wired to include the center speaker). I sold the amp and replaced it with my trusty old Alpine 3527S 4-channel amp that has been in 4 of my previous cars. It has always been rock solid and reliable. The amp specs in 3-channel mode are:
25W x 2 @ 4ohms
75W x 1 @ 4ohms (bridged)
Input sensitivity = 100mV to 2000mV (500mV at center detent)
I wired the two 25W channels (1 & 2) to the component speakers using the passive crossovers. I bridged channels 3 and 4 to create a single 75W channel for the sub. I double-checked all wires to ensure correct connections. The amp is grounded directly to the battery negative terminal. After checking all connections, I switched the HU on and tried to set the amp gain. I turned both gains down to minimum (100mV) and the HU volume to 30, which is 75% of max. I put in a good rock CD and before I even touched the gains, the amp started to get really hot to the touch. Suddenly, the music cut out and I noticed the amp status LED turned from green to red, indicating the self-protection mode was engaged. I turned the HU volume down to 20 and the green light came back on and the music came back fine with no distortion. The amp was VERY hot though, which is unusual, as this amp has never gotten more than lukewarm in my past installs, even with the tunes cranking.
I hopped online and googled the issue and found several possible explanations. One was a speaker wire short, but it didn’t fit my problem since the amp runs in the green at lower HU volume levels. Some suggested a ground issue, but again it doesn’t fit my problem, since the amp runs fine at low volume. The issue that seemed to fit my symptoms best was a gain problem, in that the input voltage (2.0V or 2000mV) was not the same as the amp gain (currently 100mV). They suggested to set my gain with a multimeter on the speaker terminals to ensure that the input values matched.
I started with the sub channel. I set the HU back to 30 volume and put in a 100hz test tone. According to the chart supplied by the audio forum, 75W @ 4ohms should read about 18.5V on the multimeter at 75% of max volume. I gradually turned up the gain on the sub channel until it was reading 18 volts. At this point the amp was staying in the green, but was pretty hot. I then moved onto the component channels. At 100mV gain, the multimeter didn’t even twitch. As I turned the gain up to max, I got about 6V on the meter at each channel. Still, there was no clipping and the amp was in the green. The 100hz test tone was so loud in the car however that I got worried I was going to blow out the speakers. I took the test tone out and inserted my rock CD and turned the HU volume down to 20 again. The music was clear. As I turned it up past 25, bam it went back into self-protection mode.
I went back inside puzzled and googled for further answers. The best I could find suggests that I’m asking my little Alpine to do too much. I have 2 tweeters at 50W RMS, 2 woofers at 200W and a sub at 200W, which is 450W total @ 4ohms. At the higher volume levels, it seems the Alpine just can’t feed enough watts to drive the speakers. I am confused however because I always thought the RMS and Peak ratings told you the maximum level the speaker could tolerate and did NOT reflect the amount of power required to drive the speaker. I thought that by using my low-power Alpine, I would protect my speakers by staying under the max watt limits. But, given my issue, do I need a more powerful amp? Is that why the Alpine does fine at lower volumes but cuts out and overheats when it gets loud? Do the RMS power ratings really tell you the amount of power you need to drive a speaker?
My confusion is enhanced based on my earlier systems. There, I used an Alpine HU to drive the front speakers and the amp bridged into two 75W channels to drive two 6x9 Boston rear speakers rated at 140W RMS. The amp never cut out even at extreme volume and never got more than lukewarm in that config, with gains set to nominal (500mV). That system could shake the car and not even blip. But, I was only using the amp to feed 150W into two channels totaling 280W.
So, I’m stuck and the trunk of my NSX is littered with wires and components until I figure this out.
Is my amp broken, or am I asking it to do too much? Should I just buy a more powerful 4-channel amp? Why does it get so hot and clip/cut out at low gain levels- I would think that it should do the opposite, since it is a low-power amp. Is it trying to overdrive itself?Any help would be greatly appreciated!!!
