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Discussion Starter · #1 ·
So I have recently gotten an intermittent hum from my speakers that is really annoying me and its only coming from my 6 channel amp (which runs my C, RS, LS, RR, LR) and not from my 2 channel amp (L,R). I've looked through a lot of options for a grounp loop but it doesn't appear to be that.


Then the other day it just shut down and the amp power light started blinking. I'd never seen that before, so at first I just figured the amp had reached the end of its lifespan and the humming was its dying gasps. But a quick check of the owners manual (I knew there was something worthwhile in one of those) showed that this could mean that the amps internal temperature had risen too high and the protection circuitry had kicked in. A quick feel of the case confirmed that the amp was HOT. Now I. not too long ago, put the amp in a new rack that definitely has less room around it than before but the humming did not start just then (but it has gotten warmer in general since then).


So long story short, can an amp that is running hot create a static/hum in its speakers?


No matter what, I know that I have to give the amp better ventilation, but I was worried that I would have to replace it and hope the hum is just a symptom of not getting enough cooling and not a permanent problem.
 

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I don't think the two problems are related. Your amp is going into thermal protection due to the more limited air flow in your new rack. I'm not sure what the hum is.


We need more information: Brand and model numbers of speakers and amps, please. How loudly do you listen? What is the speaker impedance? Is the amp run bridged? What were the exact coinditions when the amp went into thermal protection? The more info you can supply, the more chance we propellerheads have of helping you...
 

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I just noticed you refered to the noise as "static/hum"...which one is it? Are you getting hum AND static? Static can be caused by microscopic cracks in output devices caused by years of heat. They are usually the severe chest pains an amp suffers before falling to the floor dead. More info, please!
 

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Discussion Starter · #4 ·
The amp is a Kenwood KM-Z1. Specs are:

Quote:
Key Features * Home THX Certified * 125 Watts per Channel (6-Channel) * 140 Watts per Channel (6-Channel) Guaranteed

Low-Impedance * Output at 6 Ohms General Features * Home THX Certified * 6-Channel Amplification * 125 Watts per Channel

(6-Channel) at * 8 Ohms * 140 Watts per Channel (6-Channel) Guaranteed Low-Impedance Output at * 6 Ohms * Dynamic Power

(EIA Standard Rating) * 135 + 135 Watts at 8 Ohms * 265 + 265 Watts at 4 Ohms * 450 + 450 Watts at 2 Ohms * Discrete

Amplifier Circuitry * DB-25 Audio Connection for All Input Connections (cable not included) * Dual Power Supplies * 2-Speed

Silent Cooling Fan with Brushless Motor * High Linearity Output Stage * Blue LED Indicators * Gold-Plated Inputs *

Banana-Plug Compatible Speaker Connectors for all Channels * Remote Power On/Off (when used with Compatible Kenwood

Controller or Receiver Continuous Rated Output Power (FTC)


Stereo: Left and Right channels 135 watts minimum RMS/channel, both channels driven at 8 Ohms from 20 Hz to 20 kHz with no more than 0.02% total harmonic distortion

Surround: All channels 130 watts minimum RMS/channel, both channels driven at 8 Ohms from 20 Hz to 20 kHz with no more than 0.02% total harmonic distortion

Surround: All channels 150 watts minimum RMS/channel, both channels driven at 6 Ohms from 20 Hz to 20 kHz with no more than 0.02% total harmonic distortion

Damping Factor: 240 (50 Hz)

Total Harmonic Distortion

Surround: All channels 0.02 % (20–20 kHz, 130 watts, 8 Ohms) 0.001% (1 kHz, 65 watts, 8 Ohms)



Frequency Response:

Surround: All channels 3 Hz–100 kHz, +0, –3dB

Signal–to–Noise Ratio (IHF '66):

Surround: All channels Greater–than–or–equal–to 125 dB

Input Sensitivity/Impedance

Surround: All channels 1.1 V/30 k–Ohm

Power Consumption: 9 amps

Dimensions



Width:

Height:

Depth:




17–5/16 inches (440 mm)

6–1/4 inches (159 mm)

17–11/16 inches (449 mm)


Net weight: 52.9 lbs (24 kgs)
The speakers are Polk CS350-LS Center channel, RT/fx side surrounds, RT5 rear surrounds. They are all 8 ohm loads. I am running 5 channels of the amp's 6. Center = Center, Right Rear = Right Main, Left Rear = Left Main, Right Side = Right Surround, Left Side = Left Surround, The subwoofer channel is unused.


I listen to movies about -10 to -15db from reference.


I have recorded a short wav of the noise. Its a crappy recording and you need to really boost the volume to hear it but you can hear it. Its located here: http://ekroner.net/speakerhum.wav I initially thought humm when I heard it but a friend said static or distortion so I didn't want to misrepresent the sound.


I don't remember exactly when the amp went into thermal protection. It might have been overnight (I normally used to leave the amps on all the time).


Any other questions that can help let me know.
 
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